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Title:
HYDROTHERMAL TRANSFORMATION OF MICROALGAE THROUGH METAL-BASE CATALYSIS
Document Type and Number:
WIPO Patent Application WO/2011/126382
Kind Code:
A1
Abstract:
A process for producing one or more organic chemical products or fuel from biomass, and in particular from microalgae, by means of high pressure hydrothermal treatment in the presence of metal oxide or metal-base catalysts.

Inventors:
MILLER, Ian James (20 Gurney Road, BelmontLower Hutt, Wellington 5010, NZ)
BATCHELOR, Rhys Antony (91 Savage Crescent, Palmerston North 4412, NZ)
Application Number:
NZ2011/000047
Publication Date:
October 13, 2011
Filing Date:
April 07, 2011
Export Citation:
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Assignee:
MILLER, Ian James (20 Gurney Road, BelmontLower Hutt, Wellington 5010, NZ)
BATCHELOR, Rhys Antony (91 Savage Crescent, Palmerston North 4412, NZ)
AQUAFLOW BIONOMIC CORPORATION LIMITED (c/ Buddle Findlay, Level 13Clarendon Tower,78 Worcester Street, Christchurch, NZ)
International Classes:
C12P5/00; C10G1/00; C10G1/08; C12P7/24; C12P7/26; C12P13/00; C12P13/02; C12P17/00; C12P17/12
Domestic Patent References:
2008-03-20
2010-03-18
Other References:
DATABASE WPI Week201059, Derwent Publications Ltd., London, GB; AN 2010-L01132 & CN 101 787 300 A (CHINESE ACAD FISHERIES SCI YELLOW SEA FI) 28 July 2010
Attorney, Agent or Firm:
ADAMS, Matthew, D et al. (A J Park, 6th Floor Huddart Parker BuildingPO Box 949, Wellington 6015, NZ)
Download PDF:
Claims:
WHAT WE CLAIM IS:

1. A method for producing one or more organic chemical products from a feedstock of macro or microalgae, lipid-containing biomass, or any combination of these comprising: (i) heating an aqueous slurry containing said feedstock in a pressure vessel at a temperature of about 330°C to about 500°C in the presence of a metal or semi-metal oxide or base catalyst to produce a mixture comprising a dispersion of an organic phase and an aqueous phase, and

(ii) separating one or more organic chemical products from the mixture. 2. The method of claim 1, wherein the mixture is subjected to a solvent extraction step to

separate the organic phase from the aqueous phase.

3. The method of claim 1, wherein the mixture is subjected to a sequence of solvent/aqueous extraction steps with sequential changes of pH to separate the classes of organic

compounds.

4. The methods of claims 2 and 3 wherein the organic extracts are distilled, firstly to recover the extraction solvent and then to separate the resulting organic mixture into one or more purer organic chemical products.

5. The method of any one of claims 1 to 4, wherein the aqueous slurry is heated at a

temperature of about 330°C to about 374°C. 6, The method of any one of claims 1 to 4, wherein the aqueous slurry is heated at a

temperature of about 374°C to about 450°C.

7. The method of claim 1, wherein the aqueous slurry is heated for a time period of about 5 minutes to about 12 hours.

8. The method of claim 1, wherein the aqueous slurry is heated for a time period of about 5 minutes to about 60 minutes.

9. The method of claim 1, wherein the feedstock comprises solely microalgae.

10. The method of claim 1, wherein the feedstock comprises about 2% to about 60% dry weight equivalent of biomass.

11. The method of claim 1, wherein the feedstock comprises about 10% to about 30% dry

weight equivalent of biomass.

12. The method of claim 1, wherein the feedstock comprises about 5% to about 40% dry weight equivalent of biomass.

13. The method of claim 1 for the manufacture of aromatic compounds at supercritical

temperatures.

14. An organic chemical product produced according to the method defined in claim 1 selected from the group comprising pyrazines such as methyl, dimethyl, trtimethyl, ethyl or ethylmethyl pyrazine; hydrocarbons such as toluene, alkenes such as 1-nonene, pentadecene and alkanes such as pentadecane and peptadecane; methylated pyrroles, imides such as N- methyl and N-ethyl succinirnide; amides such as hexadecanamide and 9-octadecanamide; lactams such as 2-pyrrolidinone, N-methyl-2-pyrrolidinone, N-ethyl-2-pyrrolidinone, N- butyl-2-pyrrolidinone, 2-piperidinone and caprolactam; crotonaldehyde, saturated and unsaturated aldehydes and ketones such as cyclopentanone, cyclopentenone, methyl cyclopentenones, dimethyl cyclopenetenones, methyl furfural and hydroxymethyl furfural.

15. An organic chemical product of claim 14 selected from the group comprising carboxylic acids such as acetic, propionic, octanoic, dodecanoic, hexadecanoic, methylated butyric and valeric acids; lipid acids such as palmitic and oleic acids; phenol and cresol.

16. The use of ethyl benzene or styrene obtained from the mixture produced according to the method of claim 1 for manufacturing polystyrene of biologiocal origin.

17. The use of dialkylated or polyalkylated pyrazines obtained from the mixture produced

according to the method of claim 1 for manufacturing by oxidation pyrazine dicarboxylic acids or pyrazine poly carboxylic acids or anhydrides for the precursors of condensation polymers of biological origin.

Description:
HYDROTHERMAL TRANSFORMATION OF MICROALGAE THROUGH METAL- BASE CATALYSIS

FIELD OF THE INVENTION

[0001] The present invention relates to a process for producing one or more organic chemical products or fuel from biomass, and in particular from microalgae, by means of high pressure hydrothermal treatment in the presence of metal oxide or metal-base catalysts.

BACKGROUND TO THE INVENTION

[0002] A major problem for future economies will be to find alternatives sources of fuel and chemical precursors as the natural oil supplies run down, or are at least unable to fully supply demand at low cost. One such potential source of replacements is biomass, and one of the least utilized forms of biomass is microalgae.

[0003] A biofuel may be considered as any fuel, or component(s) which can contribute to a fuel, which is derived from biomass.

[0004] Biofuels are intended to provide an alternative to fossil fuels, and may be used as a source of energy, such as in transport fuels or for generating electricity, or for providing heat.

Biomass can also be used to make other useful organic chemical products, and eventually it will be highly desirable to be able to make many chemical intermediates, solvents and polymer

intermediates from biomass.

[0005] Various means of converting biomass to fuels or to useful organic chemical products have been proposed, such as fermentation, gasification and pyrolysis, however such technologies are limited because of a combination of the cost of implementation, limited product range, scale dependence and extensive waste products. Apart from fermentation, many such technologies work best when the initial biomass is dry, and many sources of biomass, particularly algae, are most readily obtained in a highly wet form. [0006] Methods of converting wet biomass to organic chemical products are known. One such technology is high-pressure liquefaction, which occurs in two variants. One is to hydrogenate the biomass direcdy by heating a slurry of biomass under a pressurized atmosphere of hydrogen in the presence of a catalyst. The alternative is simply to liquefy the biomass by heating a slurry of biomass under pressure, effectively trying to accelerate the process that led to the formation of natural oil reserves. The advantage of the second process is that biomass can be converted to a liquid that is more easily transported to a refinery, where the advantages of scale can be applied, both to the fuel processing, and to the hydrogen production. Direct hydrogenation is only feasible for the smaller scale production from biomass if the product does not need further refining, and that is not usually the case.

[0007] The concept of heating biomass in water to transform it to fuel and other organic chemical products has been reported. Thus Catallo and Junk (US Patent 6,180,845) have shown that heating cellulose in water under near-critical to supercritical conditions led to the production of phenol and substituted phenols, substituted benzene derivatives, cyclopentanone and methylated naphthalenes. Reaction of lignin under the same conditions produced various substituted phenols, naphthalenes and indenes and lipids. Highly nitrogenated biomass gave products particularly rich in phenol, toluene, phenylethanone, substituted pyridines and indole. [0008] Similarly, during the 1970s energy crises, the US Bureau of Mines produced a number of reports on the heating of lignocellulose in water, and found that oxygenated liquids that were considered to be suitable for refining to liquid fuels could be produced, and that the liquefaction process proceeded better in the presence of sodium carbonate, which was added to provide mild alkaline conditions. The hydrothermal processing of protein matter has been studied sufficiently well that a commercial plant has been built at Carthage, Missouri, although it is unclear whether the products it produced were optimal. Certainly, there is no evidence that this plant produced specialty chemicals for sale, or that it produced motor fuel for direct use without further refining.

[0009] Previously, it has been reported (I. J. Miller and S. K. Fellows, Catalytic effects during cellulose liquefaction, Fuel, 1985, 64 : 1246-1250; and I. J. Miller and E. R. Saunders, Reactions of possible cellulose liquefaction intermediate under high-pressure liquefaction conditions, Fuel, 1987, 66 : 123-129) that the heating of cellulosic biomass to 350-375 °C in the presence of phenol and other catalysts produces phenol, and similar compounds as noted above, e.g. cresols,

polyhydroxybenzenes, tetralins and indanes. The difference between these processes and the processes described in US 6,180,845 is that in the former processes significant additional hydrogenation occurred without the use of hydrogen.

[0010] Microalgae are amongst the fastest growing plants on the planet, and have the rather unusual property (for plants) of storing energy in the form of lipids, and it is possible to raise the lipid levels of some micro-algae to in excess of 50 % by weight (wt. %). Accordingly, a number of companies have developed means of growing these with the intention of using the lipids to produce biodiesel, by extracting the lipids and trans esterifying them by methods well-established in the art, or by taking these lipids and hydrocracking them, or using other refining techniques well-established in the art to produce hydrocarbons suitable for use as liquid fuels. Such methods, however, require expensive cultivation, extraction methods such as pressing are not usually available, the extractions do not work at all well if the algae is wet, which implies expensive drying is required, and the cost of the final product will be highly dependent on obtaining high yields of lipids.

[0011] An alternative would be to process wild algae, which are readily available in places such as sewage treatment facilities that are already built, but under the prevailing conditions of such operations the algae tend to devote energy towards reproduction rather than lipid accumulation, which leads to their having a high per centage of protein and nucleic acid, which is highly nitrogenous, and generally considered undesirable for fuel purposes.

[0012] On the other hand, nitrogen-containing heterocyclic chemicals are both desirable for the chemical industry, and are difficult to obtain, most having to be chemically synthesised. These are used to make polymers such as nylons, as chemical intermediates in many pharmaceuticals, as high polarity solvents, as water miscible solvents, and for many specialty uses. Finding replacements for these chemicals will be important as the oil industry declines. Further, the chemicals most easily made from proteinaceous biomass such as microalgae are, paradoxically, those most difficult to make from the oil industry, and hence their ready availability would make available new materials, such as polymers that are hydrophilic, useful for water purification or water-permeable fabrics.

[0013] Recendy, we have shown (WO/2010/030196) that when biomass is heated in water under near critical and supercritical conditions in the presence of a phosphate, chemicals that could replace products normally made from oil refining could be made. These comprised materials that could be useful as petrol substitutes, high octane petrol components, good diesel fuel, novel polymer intermediates, useful high polarity solvents, flavour enhancers, and other potential uses..

[0014] We now demonstrate that microalgae can be directed to make a variety of useful materials by reacting them hydrothermally with a set of metal bases as defined below, and some of the particular chemical materials that are made can be direcdy used both for chemicals and transport fuel, while the organic residue is expected to be suitable for further refining and the inorganic residue is suitable either for recycling, or for other uses, for example, soil conditioning and fertilizer. In particular, our invention takes specific advantage of lipid content, and accordingly will be particularly relevant to material of biological origin that is rich in lipids, or contains lipids or fatty acid components that would otherwise be unusable. Accordingly, we believe that our invention will significandy enhance the variety of sustainable feedstock of biological origin that will be required to replace those currendy obtained from the non-renewable oil industry, or at least provide the public with a useful choice. SUMMARY OF THE INVENTION

[0015] In a first aspect, the present invention relates to a method for producing one or more organic chemical products from a feedstock of algal biomass or lipid-containing biomass, or a mixture thereof, comprising: (i) heating an aqueous slurry of feedstock in a pressure vessel at a temperature above about 300°C to about 500°C in the presence of a metal or semi-metal oxide or base catalyst to produce a mixture comprising solids, a dispersion of an organic phase and an aqueous phase,

(ii) separating the solid residue from the fluid, and

(ii) substantially separating one or more organic chemical products from the mixture. [0016] In one embodiment, the oxide may be of the formula MO, M 2 0 3 or M0 2 , where M is the metal or semimetal. Examples of suitable metals include the alkaline earths, including magnesium, transition metal oxides such as zinc, copper, nickel, trivalent oxides such as aluminium, scandium, ferric, chromic, gallium, arsenious, antimony and the rare earths such as lanthanum, while the tetravalent metals include zirconium, manganese and titanium. [0017] In a further embodiment, the catalyst may be a metal base, where the basic function includes but is not limited to hydroxide, carbonate, acetate or sulphide.

[0018] In one embodiment the phases are separated, and the aqueous phase may optionally be extracted with an organic solvent immiscible in water to recover water-soluble organic material.

[0019] In a further embodiment, the whole mixture is subjected to a solvent extraction step to separate the organic phase from the aqueous phase.

[0020] In a further embodiment, any organic phase may then undergo further extraction stages to separate classes of products, including the removal of inorganic contaminants, until solvent and components are recovered by distillation.

[0021] In a further embodiment, the aqueous phase from the extracted mixture may have its pH altered and the solution may be further extracted to obtain further products.

[0022] In a further embodiment, the mixture may be distilled first to achieve a different type of separation,

[0023] In a further embodiment, such a distillation may be achieved by flaring off the water from the pressurized through a controlled release of pressure. [0024] In one embodiment the one or more organic chemical products include but are not limited to pyrazines such as methyl, dimethyl, ethyl or ethylmethyl pyrazine and trimethyl pyrazine; hydrocarbons such as toluene, xylene, ethyl benzene, styrene, alkanes and alkenes including but not limited to 1-nonene, pentadecene, pentadecane, heptadecene and heptadecane; methylated pyrroles, imides such as N-methyl and N-ethyl succinimide; amides such as hexadecanamide and 9- octadecanamide; lactams such as 2-pyrrolidinone, N-methyl-2-pyrrolidinone and other N-alkylated pyrrolidinones, 2-piperidinone and caprolactam; crotonaldehyde, aldehydes, ketones such as cyclop entenone, methyl cyclopentenone, methyl furfural and hydroxymethyl furfural.

[0025] In one embodiment the one or more organic chemical products include but are not limited to carboxylic acids such as acetic, propionic, octanoic, dodecanoic, methylated butyric and valeric acids; lipid acids such as palmitic and oleic acids; phenol and cresol.

[0026] In this specification where reference has been made to patent specifications, other external documents, or other sources of information, this is generally for the purpose of providing a context for discussing the features of the invention. Unless specifically stated otherwise, reference to such external documents is not to be construed as an admission that such documents, or such sources of information, in any jurisdiction, are prior art, or form part of the common general knowledge in the art

[0027] It is intended that reference to a range of numbers disclosed herein (for example, 1 to 10) also incorporates reference to all rational numbers within that range (for example, 1, 1.1, 2, 3, 3.9, 4, 5, 6, 6.5, 7, 8, 9 and 10) and also any range of rational numbers within that range (for example, 2 to 8, 1.5 to 5.5 and 3.1 to 4.7) and, therefore, all sub-ranges of all ranges expressly disclosed herein are hereby expressly disclosed. These are only examples of what is specifically intended and all possible combinations of numerical values between the lowest value and the highest value enumerated are to be considered to be expressly stated in this application in a similar manner. [0028] This invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more said parts, elements or features, and where specific integers are mentioned herein which have known equivalents in the art to which this invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth.

[0029] Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only. DETAILED DESCRIPTION OF THE INVENTION

[0030] In general, the present invention relates to a process where an aqueous slurry comprising feedstock, water and a metal oxide catalyst is heated to a temperature of about 300 to about 500 °C under sufficient pressure to either maintain water in the liquid state if the temperatures are sub-critical or to exceed the supercritical pressure if the temperatures are supercritical. The feedstock may comprise macroalgae, microalgae or any biomass that is primarily protein or lipid based, or any mixture thereof. The resultant mixture may be extracted or separated to produce materials that are valuable as chemicals, chemical feedstocks, or for subsequent conversion to fuel.

1. Definitions [0031] When a chemical compound is named in the singular, it refers to that specific compound, thus pyrazine would refer to 1,4-diazabenzene. When the term is used in the plural, it refers to the entire set of structures with that structural element, thus pyrazines would include all molecules with the pyrazine structure, including but not restricted to molecules with any substitution such as methylation or any molecule within which the pyrazine structure can be found. If a statement is made involving such a set of molecules, such as the term pyrroles, the subsequent use of a specific molecule that is an element of that set of molecules, such as indole, does not in any way contradict the generality of the previous statement, but should be taken as a special example or a special case.

[0032] The term "algal biomass" as used in this specification means any composition comprising algae, including both macro and microalgae. The algal biomass may be partially de- watered, i.e. some of the water has been removed during the process used to harvest the algae, for example during aggregation, centrifugation, micro-screening, nitration, drying or other unit operation The algal biomass may also comprise dried algae.

[0033] The term "lipid-containing biomass" as used in this specification means any composition equivalent to that of biological origin that contains lipids, lipid acids, or corresponding molecules. While the most common forms of such biomass are microalgae and meat and meat processing wastes, such biomass may have only residual lipids, such as the waste following olive oil production, or it may even be a waste product, such as used cooking oil, or a soap. The critical feature is that the material contains discernable amounts of molecules with the feature R-C0 2 X, where R is an alkyl group and X is any group or element.

[0034] The term "liquid fuel" as used in this specification means a liquid that without further refining can be used direcdy, or in a blend, to provide energy. [0035] The term "liquid fuel precursor" as used in this specification means a liquid that with further refining employing methods known to those practised in die art will provide a liquid fuel.

[0036] The term "oil" as used in this specification refers to any Organic liquid recovered from a reaction, and the term does not imply anything about its composition. [0037] The term "aqueous phase" as used in this specification refers to any phase that is substantially consisting of water, although it may have quite significant levels of organic material in it-

[0038] The term "organic phase" as used in this specification refers to any phase that is substantially consisting of carbon-based materials and is separable from an aqueous phase, irrespective of other aspects of composition.

[0039] The term "metal base" as used in this specification means any compound of the general formula M x B y , where x and y are numbers to ensure the rules of valence are followed, and which would react in aqueous solution with a strong acid (pH<l) to produce a salt and some other material. B may include but is not restricted to, an oxide or hydroxide, a carbonate, an acetate or a sulphide. Specifically excluded are materials where M includes the group 1 alkali metals such as lithium, sodium, potassium, rubidium and caesium. For the purposes of description, the metal base will be named according to its formal means of formatio and the claims for its use are independent of whether the structure proposed is strictly correct as long as the material remains within the formal definition. For example, a material may be termed a metal hydroxide because it was prepared by adding a solution of a hydroxide, say sodium or ammonium hydroxide, to a solution of a metal salt and a material was precipitated.

[0040] The term "comprising" as used in this specification means "consisting at least in part of; that is to say when interpreting statements in this specification and claims which include "comprising", the features prefaced by this term in each statement all need to be present but other features can also be present. Related terms such as "comprise" and "comprised" are to be interpreted in similar manner.

[0041] The term "lactam" as used in the specification refers both to a lactam or its amino acid precursor, i.e. a material capable or producing the lactam. The specific chemical lactam is similarly either the lactam or its precursor. The reason for this is that the method of identification, gas chromatography/mass spectrometry, and our method of isolation, namely final distillation would convert any precursor amino acid into a lactam, and the lactam is die desired structure of economic interest. [0042] The term "pressure vessel" as used in this specification means a container that is capable of holding a liquid, vapour, or gas at a different pressure than the prevailing atmospheric pressure within it.

[0043] "Wastewater" includes fresh or saline water, effluent from sewage treatment plants and water from facilities in which domestic or industrial sewage or foul water is treated.

[0044] The term "yield" as used in this specification refers to the weight of the recovered material as a fraction or percentage of the estimated dry weight of biomass, even though the sample actually used was never dried. The original dry weight is estimated based on actual dry weights achieved with equivalent samples. 2. Feed Materials ("feedstock")

[0045] The feedstock used in the processes of the invention may include any type of microalgae, macroalgae or lipid biomass, derived from any source, whether cultivated or wild, from a fresh water or marine environment, or any other lipid-containing material that at some stage arose from a living organism. Wastes from other processing, such as olive oil or seed oil pressings are specifically suitable. Thus for the purposes of this invention, soap would be termed biomass because its lipid component originated from either plant oil or animal fat.

3. Biomass slurries

[0046] The feedstock is fed as a slurry in a fluid, the fluid usually being water. The amount of water must be sufficient to permit the slurry to be pumped or otherwise moved, and it must be sufficient to ensure an adequate volume of fluid phase in a subcritical reaction, or to maintain the required pressure in a supercritical reaction, and therefore the amount of water required depends on the final temperature and pressure desired, the pumping equipment used, and the reactor configuration. It will also depend on the nature of the biomass, as some biomass, particularly dried biomass, absorbs water.

[0047] The more dilute the feedstock, the more energy is wasted heating water hence higher concentrations are desirable provided other criteria are met. The lower practical concentration of microalgae is about 2% by weight, while from an operational point of view, for a continuous flow process 50% by weight of feedstock is an upper limit, with about 80% for a batch reactor with proper allowance for headspace, however charring will occur at higher feedstock levels. The actual concentration used will be influenced by cost, including the cost of concentrating microalgae prior to use in this invention, and this invention applies to all such concentrations. 4. Heating

[0048] Preferably the feedstock is heated to between about 300°C to about 374°C, more preferably from 340 "C to about 374°C if the reaction is intended to take place under subcritical conditions. [0049] The feedstock is heated to between 374°C to about 500 "C, preferably between about 374°C to about 450°C if the reaction is intended to take place under supercritical conditions.

[0050] The feedstock may be heated for a time period of about 0.5 seconds to about 12 hours, preferably for about 5 minutes to about 3 hours, even more preferably for about 5 minutes to about 60 minutes. As a general principle, the lower the chosen temperature, the longer the heating time is required to achieve a specific objective. Accordingly, the heating time can be selected for convenience. The overall yield increases progressively with time, at least to 30 minutes, with the greatest increase up to 10 minutes, but the increased yield after 10 minutes sometimes arises through the formation or extraction of higher molecular weight products, hence shorter times may be more desirable if the volatile components are more desired. [0051] At a given temperature, the relative product distribution is a function of time, therefore there is no optimum reaction time other than in terms of which are the desired products. As a general rule, longer times favour condensation reactions, hence the products are less volatile, more viscous, and generally are more likely to require significant downstream processing hence shorter times may be preferred, even if total processing of microalgae is not achieved, in order to maximize the production of higher value products.

[0052] On the other hand, some of the higher molecular weight products have structures that are difficult to obtain otherwise, and a reaction that is run specifically to obtains such products using the methods of this invention are included within the claims of this invention.

5. Pressure [0053] The pressure generated is dependent on the amount of water present, as this water provides the pressure. There must be sufficient water present to provide a liquid phase if subcritical, and the appropriate water partial pressure if supercritical, as otherwise excessive charring may occur.

[0054] Additional pressure may be applied to achieve certain objectives, e.g. increasing the pressure generally increases the yield of aromatic products. [0055] In various embodiments, the pressure vessel which may be utilised for the processes of the present invention may be a tank, a batch reactor, a continuous reactor, a semi-continuous reactor of stirred-tank type or of continuous staged reactor-horizontal type or vertical-type, or alternatively of a tubular-type or tower-type reactor. A fluidised-bed or slurry-phase reactor may also be employed. Such vessels and reactors may be further specified as appropriate for use with the type or phase of catalysts and/ or reagents which may be used.

6. Catalysts

[0056] In the process of the invention, a metal base catalyst is added to the biomass prior to heating. This may be by direct addition, i.e. adding the catalyst to the slurry, or by forming it in situ, e.g. a metal hydroxide may be formed by dissolving a metal salt in the slurry, and then by adding the appropriate equivalents of hydroxide, and if necessary adjusting the pH with acid or alkali. Forming it in situ has the advantage that if the metal ion complexes in any way with the biomass, the resulting catalyst is formed on the surface of the biomass, and hence is more readily available.

7. Separating the one or more organic chemical products from the mixture [0057] Optionally, before separating one or more organic chemical products, the mixture resulting from the heat and pressure treatment step is filtered to recover solids, including catalyst or reagent materials.

[0058] One or more organic chemical products can be separated from the mixture resulting from the heat and pressure treatment step by any means known in the art including decanting the organic fraction off the aqueous fraction, or extracting the fractions with one or more organic solvents. Options for extracting the aqueous fraction and organic fraction are described below.

[0059] In one embodiment, the aqueous fraction or the biomass residue may be extracted with one or more organic solvents to obtain organic material adhering to the biomass residue or forming a colloidal distribution in the aqueous fraction or dissolved in the aqueous fraction.

[0060] Extraction may be carried out using any organic solvent or combination of organic solvents that are insoluble in water. Examples include, but are not restricted to, light hydrocarbons such as light petroleum spirit, pentane, methylene chloride and other halogenated hydrocarbons, toluene and other aromatic hydrocarbons, ethyl acetate and other esters, diethyl ether and other ethers, and also materials such as propane and butane that are gases at normal temperatures but can be liquids under suitable pressure, if such pressure was applied. [0061] In one embodiment, the organic fraction may be simply separated from the aqueous fraction to provide an organic chemical product that may be used as a fuel precursor. In another embodiment the organic fraction may be further separated into one or more organic chemical products that may be useful in applications including but not limited to biofuel production, or providing feedstock for other chemical processes.

[0062] In one embodiment, the further separation step may be a distillation step, either single or multistage, or by flaring and condensing volatiles from the reaction. The distillation step may be prior to extraction, in which case water is also distilled. Various fractions obtained by extraction or partitioning may also be distilled.

[0063] Separation of organic chemical products can be achieved by acidifying or alkalysing the aqueous fraction prior to extraction into an organic solvent, or by extracting a solution of organics in an organic solvent with aqueous acid or alkali. For example, acidification of the aqueous fraction will protonate any organic acids present, allowing them to be subsequendy extracted from the aqueous fraction with organic solvents. In one embodiment the aqueous fraction is alkalised and the resulting alkaline aqueous fraction is extracted with organic solvent to produce nitrogen bases. Acidification and. basification may be carried out in any order.

[0064] Organic chemical products can also be obtained from the aqueous fraction. If the aqueous fraction is acidified and extracted with solvent such as pentane or methylene chloride carboxylic acids are obtained, mainly acetic, propionic, and methylated butyric and valeric acids. These products are likely obtained by deamination of amino acids, and some lipid acids, including palmitic and oleic acids. Phenol and cresol were also found. Lactams such as 2-pyrrolidinone may also dissolve in the aqueous fraction, in which case they may cause some organic materials such as aromatic hydrocarbons to accompany them. [0065] If the aqueous fraction is made basic, extraction will obtain organic bases. Since some bases include piperidine, the pH should be raised to 12 to extract this material. Lactams will also be extracted with the organic bases.

[0066] The order of pH variation is not critical, and the first extraction may be carried out at either high or low pH, or if desired, at an intermediate pH to gain a particular separation. For example, an initial extraction at pH 7 would lead to a fraction contianing hydrocarbons, pyrazines, lactams, etc, but leave bodi carboxylic acids and saturated amines in solution. [0067] Changing the pH of the organic fraction may allow some organic chemical products present in the organic fraction to be able to be extracted into an aqueous solution. For example, if an acid solution that has been extracted is then made alkaline, diazines and similar organic chemical products can be extracted using organic solvents. [0068] In the examples below, some of the extractions did not lead to complete separation, a problem that particularly applies to lactams. Our claims relate to the fact that the separations are generally useful, despite the fact that they are not 100% efficient.

[0069] The nature or relative concentration of various components of the volatiles formed at supercritical temeratures is usually different from those obtained under subcritical conditions, hence either set of conditions may be desirable for specific purposes.

[0070] The organic chemical products obtained varied somewhat depending on the nature of the catalyst, but there were a number of products occurring at levels of approximately 2% that did not appear to change significandy. One such compound was indole, and there were a number of higher boiling materials that appeared to contain pyrrole or pyrazine rings. [0071] Certain fractions or chemical compounds may be separated and used as such, while the residue, which includes the higher boiling fraction, may be hydrocracked or otherwise treated by methods known to those practised in the art to convert them to more conventional fuels.

[0072] The organic chemical products obtained by the process of the invention may be separated into their chemical components using known purification techniques. These products can be used in many applications, including as a chemical feed stock for the synthesis of other chemicals. For example, the pyrazines can be used as flavour additives in the food industry, indoles may be used in the perfume industry, while the lactams have many uses, including as intermediates for polyamides or for inclusion as an amide in a condensation polymer, or as high boiling polar solvents. Amides produced by the process of the invention may be useful for subsequent conversion into solvents such as acetonitrile, or into surfactants and cationic detergents.

[0073] The separated chemical components produced by the process of the invention may also be used as chemical intermediates for the production of biopolymers. The use of lactams to make polyamides has been noted, but the oxidation of 2,5-dimethylpyrazine makes available a useful diacid, which may be a component of polyamides, while diols produced by the reaction with macroalgae may have value in polyesters. Such polymers, with high levels of nitrogen or oxygen may have particularly useful properties in terms of interaction with water and polar molecules that are difficult to get otherwise. DISCUSSION OF EXAMPLES

[0074] Determination whether there was a catalytic effect was made on the grounds that the nature of the products changed. The products formed were determined by gas

chromatography/ mass spectrometry, and in some cases a chemical may have been present but not separated and clearly identified, in which case it is not reported.

[0075] Establishment of catalytic effects required a reference of microalgae processed without a catalyst. As shown by the examples, there were two basic approaches. Method 1 involved injecting a very small sample of slurry into a pre-heated reaction 2one. This gave very rapid heat-up, but it also gave an erratic yield measurement, mainly because the amount of material injected was more difficult to determine. Method 2 involved relatively slow heating of a better defined mass of algae, but reactions that were nominally supercritical had also spent approximately an hour under general subcritical temperatures (300-374 °C) and probably ¾ hr between 200 and 300 °C Accordingly, these reactions should be viewed as supercritical reactions of subcritical products.

[0076] Because the major point of interest was the relative effects of various catalysts, it was important to keep a constant feedstock. Accordingly, a standard sample of microalgae, collected on the same day, subdivided into sample packs and frozen, were used for our experiments. This microalgae was chosen because it had reasonable levels of protein, nucleic acid, lipids and carbohydrate content. Because pyrazines and lactams can only come from protein and nucleic acid, and the diesel components from lipid acids, and since our oxygenated petrol components should only come from carbohydrate, the relative yields in the following tables should change significantly if the relative amounts of the precursors changed in the biomass. For example, if the feedstock had significant amounts of olive oil pressing wastes, the yield of diesel components would increase significantly while the pyrazines and lactams would decrease.

[0077] The results of these reactions are summarized in the following tables, however certain warnings should be kept in mind. Besides the compositional asp[ects noted above, the

determination of yields is somewhat error-prone, so no particular significance should be placed on small differences. The measurement of proportions of given materials may also be in error since a material may be there, but if there is also an impurity not separable by gas chromatography, it may not be identifiable by mass spectrometry and it presence will be missed.

[0078] The effect of oxides at subcritical temperatures is given in Table 1

[0079] Table 1. Variability of product with respect to Basic Catalyst in water under subcritical conditions (300-350 °C) Catalyst Yield % A % P % L % D % PA Total

(g)

None 5.6 15.0 8.0 6.0 4.0 2.0 35

Ca(OH) 2 2.5 - 19.8 8.9 6.0 34

MgO 3.7 12.2 10.6 4.0 16.0 - 43

Fe 2 C>3 ND - 13.8 7.1 1.4 7.5 29

Cr 2 0 3 5.0 - 8.2 10.4 11.1 0.9 30

Sb 2 0 3 6.2 10.2 3.6 1.3 16.9 1.2 33

Ti0 2 6.7 9.5 4.9 5.4 17.9 5.5 43

Zr0 2 6.6 4 4.8 4.5 17.5 - 30

A - aromatics, P - pyrazines, L = Lactams, D = material suitable for direct use as diesel, PA = potential oxygenated petrol additives; ND, not determined method 1.

[0080] The addition of bases to the reaction was expected to remove the acids as they were formed, and thus remove them from further reactivity. This seemed to be realized for calcium hydroxide and magnesium oxide where, with 3.7 g of oxide, the yields of oil were significandy lower than some other reactions where salts would not be expected to form, e.g. with the antimony, titanium and zirconium oxides. When the amount of calcium hydroxide was raised to almost 14 g, the yield was trivial. Accordingly, for basic metal oxides, an excess of catalyst is not desirable when the reactions are carried out this way.

[0081] Further, in general the yields at subcritical temperatiures are less than those at supercritical temperatures, and accordingly subcritical reactions are in general suboptimum. The reason for that appears to be that at subcritical temperatures, certain products are not made or are made only in relatively small amounts, particularly aromatic hydrocarbons. Finally, although the diesel fraction as listed is high, close examination of the examples show that this usually is a result of much of the material being recovered as lipid acids or amides, and these would require further processing to be used as diesel. [0082] The effect of oxides and other bases at supercritical temperatures is given in Table 2

[0083] Table 2. Variability of product with respect to Basic Catalyst in water under supercritical conditions (400 °G)

Catalyst Yield % A % P % L % D % PA Total

Cg)

None 5.5 9 8.0 4.0 6.0 3.0 30

CaC0 3 5.8 7.8 10.4 - 4.8 2.9 26

Ca(0H) 2 4.6 12.3 10.7 12.9 9.5 7.0 52 MgO

ZnO 5.9 8.2 12.3 21.5 4.9 2.8 50

Fe 2 03 6.9 5.2 5.2 14.5 6.0 2.6 47

Cr 2 0 3 7.6 4.8 4.3 8.5 15.5 - 33

Sb 2 0 3 8.3 6.0 5.2 15.3 12.6 1.4 40

Zr0 2 6.3 10.0 2.0 11.2 14.7 1.6 40

FeS 5.2 7.3 5.8 19.5 8.6 2.8 44

A— aromatics, P— pyra2ines, L— Lactams, D— material suitable for direct use as diesel, PA = potential oxygenated petrol additives; [0084] The bases listed below fall into two classes: those that are expected to react with intermediate acids, such as Ca(OH), and those, such as TiO, and FeS which probably do not. However, there appears to be no clear difference in products based on this fact alone.

[0085] The most obvious observation from Table 2 is that it is possible to considerably vary the proportions of the various components. The highest yield of aromatic hydrocarbons was given by calcium hydroxide, which gave no aromatics in the subcritical reaction, hence the higher temperatures are clearly beneficial to the formation of aromatic hydrocarbons in this example. Zinc oxide gave the best yield of lactones, although iron sulphide also gave a high proportion of lactones. The zirconium dioxide gave the highest yield of diesel replacements, and since it also gave a reasonably high proportion of aromatic hydrocarbons, it may be a desirable catalyst for fuel production. The reason its overall yield is a litde lower is that for some reason the yield of pyrazines was very low.

[0086] The yield of pyrazines was much higher for those bases where the catalyst could reasonably be expected to form a salt with an acid or an amino acid, such as the oxides/hydroxides of the divalent metal ions. However, in part this higher yield of pyrazines may be because pyrazines continue to be made, but other reactions are suppressed, as the overall yields of these materials was lower.

[0087] Calcium carbonate gave pyrroles in the subcritical reactions, but not in the supercritical reactions, which is suggestive that pyrroles will react further, and are probably in the high molecular weight fractions. If pyrroles are a desired product, then only subcritical reactions should be considered.

[0088] On the other hand, the reaction with a relatively large amount of magnesium oxide at 330 °C gave the expected hydrocarbons but relatively low levels of lactams and heterocycles, and also a relatively low yield of volatiles in the boiling range detected here. This is probably a consequence of materials such as amino acids or small peptides being formed, which would not be extractible by the methods used, and not reacting further.

EXAMPLES

Example 1. No catalyst Method 1. [0089] A slurry of 8% microalgae in water was subjected to the procedures of Method 1 to give yields, of oil in the range 10-20%. The GCMS analyses of the relative compositions of the methylene chloride extract of the oil gave (as per centages of that extract that volatalized properly) were as follows:

[0090] Subcritical reaction, oil phase: p-cresol (1.6%), p-ethyl phenol (1%), N- methylsuccinimide (1.8%), 2-pyrrolidinone (0.9%), N-ethyl-2-pyrrolidinone (2%), 2-piperidinone (2.3%), pentadecene (2%), heptadecane (2.8%), hexadecanoic acid (13%), oleic acid (4.9%) hexadecanamide (1.8%), and some unidentified compounds.

[0091] Subcritical reaction, aqueous phase: acetic acid (25.4%), propionic acid (6.2%), 2- pyrrolidinone (5.8%), 2-piperidinone (6%), benzenepropanoic acid (1.4%) and some unidentified compounds.

[0092] Supercritical reaction, oil phase: N-methylsuccinimide (1.8%), 2-piperidinone (2.5%), heptadecane (1.2%), and some unidentified compounds.

[0093] Supercritical reaction, aqueous phase: acetic acid (29.4%), propionic acid (4.5%), N- methyl piperidine (13%), 2-pyrrolidinone (4.3%), 2-piperidinone (5.5%), benzene propanoic acid (1.4%) and some unidentified compounds.

Example 2. No catalyst, Method 2.

[0094] A slurry of 8% microalgae in water was subjected to the procedures of Method 2 to give yields of oil of 30%. The GCMS analyses of the relative compositions of the methylene chloride extract of the oil gave (as per centages of that extract that volatalized properly) were as follows: [0095] Subcritical reaction, oil phase: toluene (1.8%), xylene or ethyl benzene (3.8%), styrene (3.4%), methyl pyrazine (2.3%), 2,5-dimethyl pyrazine (2.6%), trimethyl pyrazine (3.3%), 2- methylcyclopent-2-en-l-one (1.7%), 2,3-dimethylcyclopent-2-en-l-one (1.5%), butyrolactorie (1%), 2-piperidinone (2.6%), pentadecene (2.5%), heptadecane (1.1%), oleiamide (2.1%), and some unidentified compounds. [0096] Subcritical reaction, aqueous phase: acetic acid (22.3%), propionic acid (4.4%), butanamide (3.1%), 2-pyrrolidinone (2.5%), 2-piperidinone (4.1%), palmitic acid (6.5%), oleic acid (1.4%), and some unidentified compounds.

[0097] Supercritical reaction, oil phase: toluene (4.0%), ethyl benzene (6.9%), xtylene (1.7%), styrene (1.9%), methyl pyrazine (2.9%), 2,5-dimethyl pyrazine (3.0%), trimethyl pyrazine (2.3%), 2- methylcyclopent-2-en-l-one (2.2%), 2,3-dimethylcyclopent-2-en-l-one (1.9%), N-ethyl-2- pyrrolidinone (3.9%), indole (1.8%), 3-methyl indole (1.9%), pentadecene (1.4%), pentadecane (2.2%), and numerous unidentified products.

[0098] Supercritical reaction, aqueous phase extract: acetic acid (15.1%), N-methyl-2- pyrrolidinone (3.7%), 2-pyrrolidinone (<4.7%) and some unidentified compounds.

Example 3 Calcium Carbonate

[0099] A slurry of 18.6 g microalgae in water such that the total volume was 300 mL and containing calcium carbonate (1 g) was subjected to the procedures of Method 2. The GCMS analyses of the relative compositions of the methylene chloride extract of the oil (5.79 g oil phase, 0.97 g in the aqueous phase) gave (as per centages of that extract that volatalized properly) were as follows:

[00100] In the oil phase, toluene (2.2%), ethyl benzene (5.6%), methyl pyrazine (2.3%), 2,5- dimethyl pyrazine (3%), ethyl pyrazine (1.9%), trimethyl pyrazine (3.2%), 2-methylcyclopent-2-en-l- one (1.8%), 2,3-dimethylcyclopent-2-en-l-one (1.1%), pentadecene (1.3%), heptadecane (1.4%), hexadecanamide (2.1%) and numerous high-boiling unidentified products. In the aqueous phase, acetic acid (24%), propionic acid (3.7%),, acetamide (7.1%), butanoic acid (5.4%), butanamide (3.3%), N-ethyl 2-pyrrolidinone (0.7%), benzene propanoic acid (5.7%), and numerous unidentified products.

Example 4 Calcium hydroxide [00101] Slurries of 18.6 g microalgae in water and 1.25 g calcium hydroxide were subjected to the procedures of Methods 1 and 2. GCMS analysis of a methylene chloride extracts gave (as per centages of that extract that volatalized properly):

[00102] Under supercritical conditions, the oil yield from method 2 was 4.58 g and the products were: pyrrolidines (2.4%), toluene (3%), ethyl benzene (6.9%), methyl pyrazine (3.4%), 2,5-dimethyl pyrazine (3.2%) trimethyl pyrazine (4.1%), cyclopentanone (1%), 2-methylcyclopent-2-en-l-one (2%), 3-methylcyclopent-2-en-l-one (2%), 2,3-dimethylcyclopent-2-en-l-one (« 2.0%), p-cresol (2.1%), p-ethyl phenol (3%), N-methyl-2-pyrrolidinone (* 6.8%), N-ethyl-2-pyrrolidinone (3.2%), 2- piperidinone (2.9%), indole (2.3%), 3-methyl indole (1.5%), txidecene (0.9%), tetradecane (1.7%), pentadecene (2.3%), pentadecane (2.7%), heptadecane (1.1%), hexadecanamide (0.8%) and numerous unidentified products. Apart from one compound, this reaction product was essentially free of materials boiling higher than hexadecanamide.

[00103] The aqueous fraction gave approximately 10% further yield, and contained acetic acid (15%), butanoic acid (4.5%), benzenepropanoic acid (6.8%) and a number of unidentified materials present in small amounts. [00104] In the subcritical reactions (using method 1) the products were: pyri idine (4.6%), methyl pyrazine (8.3%), 2,5-dimethyl pyrazine (3.4%) trimethyl pyrazine (2.1%), 2-methylcyclopent-

2- en- -one (3.6%), 3-methylcyclopent-2-en-l-one (1.9%), p-cresol (1.4%), p-ethyl phenol (2.4%), N-methyl succinimide (4%), N-ethyl 2-pyrrolidinone (1.7%). 2-piperidinone (5.4%), indole (1.5%),

3- methyl indole (1.5%), and numerous unidentified products. Example 5 Calcium hydroxide

[00105] A slurry of 18.3 g microalgae and 3.7 g of calcium hydroxide in 330 mL water was heated to 350 °C in a bomb for 30 minutes, cooled, and filtered. The solution was extracted with methylene chloride to give 2.5 g oil. Extraction of the solution following acidification to pH 1 gave a further 0.47 g of product, while after converting that to pH lr4, a further 0.16 g was extracted. GCMS analysis of a methylene chloride extracts gave (as per centages of that extract that volatalized properly): -

[00106] For the neutral extract, dimethyl disulphide (4.3%), N-methyl pyrrole (3.8%), cyclopentanone (1.4%), 2-methyl cyclopent-2-en-l-one (2.4%), 2,3-dimethylcyclopent-2-enone (2.2%), methyl pyrazine (4.3%), 2,5-dimethyl pyrazine (4.6%), ethyl pyrazine (1.8%), 2-ethyl-6- methyl pyrazine (3.7%), trimethyl pyrazine (5.4%), N-ethyl 2-pyrrolidinone (2.1%), N-butyl 2- pyrrolidinone (3.6%), 2-piperidinone (3.2%), and numerous unidentified products.

[00107] For the acidified extract, methyl pyrazine (4.3%), butanoic acid (4.3%), 2-methyl- plus 3- methyl butanoic acid (9.6%), valeric acid (5.3%), 4-methylpentanoic acid (10.9%), benzene propanoic acid (8%), 2-pyrrolidinone (1.1%), 2-piperidinone (5.1%) and numerous unidentified components. [00108] For the basic extract, N-methyl piperidine (22.8%), 2,5-dimethyl pyrazine (4%), trimethyl ;pyrazine (2.5%), and numerous unidentified components.

Example 6 Excess calcium hydroxide

[00109] A slurry of 18.3 g microalgae and 15 g of calcium hydroxide in 330 mL water was heated to 350 °C in a bomb for 30 minutes, cooled, and filtered. The solution was extracted with methylene chloride to give 0.27 g oil. GCMS analysis of a methylene chloride extracts gave (as per centages of that extract that volatalized properly): dimethyl disulphide (4.1%), N-methyl piperidine (7.7%), N- ethyl piperidine (4.3%), N-ethyl pyrrole (2.1%), cyclopentanone (1.2%), 2,3-dimethylcyclopent-2- enone (2.6%), N-ethyl-2-pyrrolidonone (2%), and numerous unidentified products. [00110] After acidification to pH 1, 0.22 g of material was recovered, which contained : dimethyl disulphide (1%), pyrrole (0.5%), N-ethyl pyrrole (6.8%), cyclopentanone (0.7%), 2,3- dimethylcyclopent-2-enone (2.6%), N-ethyl-2-pyrrolidonone (2%), 2-methyl propionic acid (6.2%), butanoic acid (13.2%), 2-methyl butanoic acid (7.7%), 3-methyl butanoic acid (3.2%), pentanoic acid (4.2%), 4-methyl pentanoic acid (11.4%), 2,3-dimethyl cyclopent2-en-l-one (0.7%), 2-piperidinone (1.5%), and numerous unidentified components. After adjusting the pH to 14, 0.28g of material was recovered, which comprised: heptan-l-ol (6.8%), cyclopentanone (0.5%), N-methyl piperidine (16.1%), 3-picoline (1.2%), N-methyl-2-pyrrolidinone (3.4%), N-ethyl-2-pyrrolidinone (4.7%), N- ethyl butanamide (5.5%), 2-methyl cyclopent-2-en-l-one (1.3%), 2,3-dimethyl cyclopent-2-en-l-one (1.2%) and numerous unidentified components. Example 7 Ferric oxide

[00111] A slurry of 8% microalgae in water and 5% ferric oxide was subjected to the procedures of Method 1. GCMS analysis of a methylene chloride extract of the oil gave (as per centages of that extract that volatalized properly):

[00112] In the supercritical reactions: pyrimidine (4.6%), pyrrole (5.2%), toluene (2.5%), methyl pyrazine (6.8%), 2,5-dimethyl pyrazine (2.3%) trimethyl pyrazine (1.4%), cyclopentanone (1%), cyclopent-2-en-l-one (1%) 2-mefhylcyclopent-2-en-l-one (2.6%), 3-methylcyclopent-2-en-l-one (1.4%), butyrolactone (1.9%), 5-methyl-2-furaldehyde (1.9%), p-cresol (4.6%), p-ethyl phenol (1.8%), N-methyl succinimide (2.7%), hydantoin (1), 2-piperidinone (5.1%), indole (2.8%), approximately 5% of N-alkylated 2-pyrrollidinones and numerous unidentified products. [00113] in the subcritical reactions: pyrimidine (5.2%), methyl pyrazine (8.3%), 2,5-dimethyl pyrazine (3.4%) trimethyl pyrazine (2.1%), 2-methylcyclopent-2-en-l-one (3.6%), 3- methylcyclopent-2-en-l-one (1.9%), 2,3-dimethylcyclopent-2-en-l-one (2.0%), p-cresol (1.4%), p- ethyl phenol (2.4%), N-methyl succi irnide (4%), N-ethyl 2-pyrrolidinone (1.7%). 2-piperidinone (5.4%), indole (1.5%), 3-methyl indole (1.5%), pentadecene (0.7%), heptadecane (0.7%) and numerous unidentified products. [00114] A similar reaction using method 2 under supercritical conditions gave an oil yield of 6.88 g and a further 0.56 g from the aqueous fraction. The composition of the oil fraction was toluene (1.5%), xylene (3.7%), methyl pyrazine (1.7%), 2,5-dimethyl pyrazine (1.8%) trimethyl pyrazine (1.7%), 2-methylcyclopent-2-en-l-one (1.1%), 2,3-dimethylcyclopent-2-en-l-one (1.5%), indole (1.6%), 3-methyl indole (1.5%), N-methyl 2-pyrrolidinone (6.2%), N-ethyl 2-pyrrolidinone (4.8%), N-butyl 2-pyrrolidinone (3.5%), pentadecene (1.6%), heptadecane (1.1%), hexadecanoic acid (2.3%), hexadecanamide (1%) and numerous unidentified products. A high fraction of the yield came in very few GC peaks, and these remained unidentified because they appeared to contain at least two unresolved components. The aqueous fraction contained acetic acid (17.4%), propanoic acid (2.2%), 2-pyrrolidinone (3.6%), benzenepropanoic acid (4.7%), again three GC peaks that contained more than one component, and numerous unidentified components.

Example 8 Titanium dioxide

[00115] A slurry of 18.6 g of microalgae together with 0.9 g of titanium dioxide was heated to 350 °C for the subcritical reaction, 400 °C for the supercritical reaction, held for 30 minutes at the reaction temperature, then cooled and filtered. The fluid was extracted with methylene chloride, then the aqueous solution was acidified to pH 1, and further extracted with methylene chloride.

GCMS analysis of a methylene chloride extracts gave (as per centages of that extract that volatalized properly):

[00116] In the subcritical reactions the oil (6.68 g) comprised: toluene (2.4%), ethyl benzene (5.4%), styrene (1.7%), 2,5-dimethyl pyrazine (2.1%), trimethyl pyrazine (2.8%), 2,3- dimethylcyclopent-2-en-l-one (3.6%), 3-methylcyclopent-2-en-l-one (1.9%), N-methyl 2- pyrrolidinone (3.4%). N-ethyl 2-pyrrolidinone (2%). indole (1.8%), 3-methyl indole (1%), pentadecene (2.2%), probably pentadecane (2.1%), heptadecane (1.7%), methyl 9-hexadecenoate (2.7%), hexadecanoic acid (4.5%), oleic acid (2%), hexadecanamide (1.6%), 9-octadecenamide (1.1%) and numerous unidentified products. Following acidification to pH 1, the aqueous fraction gave an extract containing acetic acid (23.7%), propanoic acid (5.3%), 2-methyl propanoic acid (6.1%), butanoic aicd (24.3%), 2-methyl butanoic acid (6.3%), 3-methyl butanoic acid (5.5%), hexanoic acid (0.3%), 4-methyl pentanoic acid (8%), cyclopentanone (0.2%), methyl pyrazine (0.2%) and numerous unidentified products. Example 9 Zinc oxide

[00117] A slurry of 18.6 g of microalgae together with 0.9 g of zinc oxide was heated to 350 "C for the subcritical reaction, 400 °C for the supercritical reaction, held for 30 minutes at the reaction temperature, then cooled and filtered. The fluid was extracted with methylene chloride, then the aqueous solution was acidified to pH 1, and further extracted with methylene chloride. GCMS analysis of a methylene chloride extracts gave (as per centages of that extract that volatalized properly):

[00118] In the supercritical reactions the oil (5.89 g) comprised: toluene (2.5%), ethyl benzene (4.7%), styrene (1%), cyclopentanone (0.9%), 2-mefhyl cyclopent-2-en-l-one (1.9%), methyl pyrazine (3.3%), 2,5-dimethyl pyrazine (3.1%), 2-efhyl-6-mefhyl pyrazine (2.4%), trimethyl pyrazine (3.5%), N-methyl 2-pyrrolidinone (7.3%), N-ethyl 2-pyrrolidinone (3.8%), N-butyl 2-pyrrolidinone (4.6%), 2-piperidinone (5.8%), indole (1.4%), 3-methyl indole (2%), pentadecene (2.3%), heptadecane (1.4%), hexadecanamide (1.2%) and numerous unidentified compounds.

[00119] The supercritical aquous extracts comprised: acetic acid (18.9%), acetamide (8.5%), propanoic acid (5.3%), 2-methyl propanoic acid (4.8%), 2-methyl propanamide (1.9%) butanoic acid + N-methyl acetamide (16.6%), butanamide (3.2%), 2-methyl butanoic acid (5%), 4-methyl pentanoic acid (2.9%), N-methyl pyrrolidinone (2.9%), 2-pyrrolidinone (4%), 2-piperidinone (8.6%) and numerous unidentified compounds.

Example 10 Chromic Oxide [00120] A slurry of 18.6 g of microalgae together with 1.8 g of chromic oxide was heated to 300 ,J C for the subcritical reaction, 400 °C for the supercritical reaction, held for 30 minutes at the reaction temperature, then cooled and filtered. The fluid was extracted with methylene chlorideand following evaporation, an oil (7.61 g supercritical, 5.01 g subcritical), then the aqueous solution was acidified to pH 1, and further extracted with methylene chloride. GCMS analysis of a methylene chloride extracts gave (as per centages of that extract that volatalized properly):

[00121] In the subcritical reactions the oil comprised: 2-methyl cyclopent-2-en-l-one (0.9%), methyl pyrazine (2.9%), 2,5-dimethyl pyrazine (2.3%), ethyl pyrazine (0.55%), 2-ethyl-3-methyl pyrazine (0.55%), trimethyl pyrazine (1.9%), 2-piperidinone (4.0%), caprolactam (6.4%) pentadecene (0.4%), heptadecene (1.2%), heptadecane (1.2%), tetramethyl-hexadec-2-ene (4%), 3-eicosyne (0.9%), hexadecanamide (1.8%), octadec-9-enamide (1.9%), 3.6-diisobutyl-2,5-piperazinedione (9.2%), condensed pyrazine diones (6.5%) and numerous unidentified compounds. [00122] The subcritical aqueous solution contained pyrimidine (2.1%), 2-methylpropionic acid (11.8%), butanoic acid (7%), 2-methylbutanoic acid (10.8%) and numerous unidentified compounds.

[00123] In the supercritical reactions the oil comprised: toluene (1.8%), ethyl benzene (2.8%), methyl pyrazine (1.1%), 2,5-dimethyl pyrazine (1.3%), ethyl pyrazine (0.6%), trimethyl pyrazine (1.3%), N-ethyl-2-pyrrolidinone (1.7%), 2-piperidinone (2.5%), alkylated pyrrolidinone (4.3%) 3- methyl indole (1.4%), pentadecene (2.6%), heptadecene (1.3%), heptadecane (2.8%), oleic acid (2.8%), hexadecanamide (3.2%), octadec-9-enamide (2.8%) and numerous unidentified compounds.

[00124] The supercritical aqueous solution contained acetic acid (7.9%), 3-methyl butanol (6.9%), propanoic acid (4.9%), 2-methylpropionic acid (6.1 %), butanoic acid (18.8%), 3- methylbutanoic acid (4.1%) 2-methylbutanoic acid (7.1%) 2-methyl cyclopent-2-en-l-one (1.7%), 2,3-dimethyl cyclopent-2-en-l-one (0.8%), 2,5-dimethylpyrazine (1.2%), trimethylpyrazine (2.1%) and numerous unidentified compounds.

Example 11 Cupric oxide

[00125] A slurry of 18.6 g of microalgae together with 1.8 g of cupric oxide was heated to 250 °C, 300 °C and held for 30 minutes at the reaction temperature, then cooled and filtered. The fluid was extracted with methylene chloride, then the aqueous solution was acidified to pH 1, and further extracted with methylene chloride. GCMS analysis of a methylene chloride extracts gave (as per centages of that extract that volatalized properly)

[00126] The aqueous mixture of the sample heated to 250 °C gave 0.38 g of extractible oil, comprising: N-methyl pyrrole (2.8%), pyridine (2.9%), methyl pyrazine (4.9%), 2,5-dimethyl pyrazine (3.9%), ethyl pyrazine (2.2%), 2-ethyl-3-methyl pyrazine (3.3%), ethyl-methyl pyrazine (0.9%), trimethyl pyrazine (4.4%), cyclopentanone (0.8%), 2-mefhyl cyclopent2-en-l-one (2.7%), 2,3-dimethyl cyclopent2-en-l-one (1%), trimethyl hydantoin (1.1%), 2-piperidinone (3.5%), condensed pyrazines (4%) and numerous unidentified components. After acidification to pH 1, 0.25 g of material was recovered, which contained : 2-methyl propionic acid (7%), butanoic acid (23.3%), 2-methyl butanoic acid (8.8%), 3-methyl butanoic acid (4%), pentanoic acid (4.7%), 4-methyl pentanoic acid (13.4%), pyrimidine (0.8g), ethyl pyrazine (0.8%), 2,3-dirnethyl cy clop ent2-en- -one (0.3%), 2-piperidinone (6.9%), and numerous unidentified components. After adjusting the pH to 14, 0.3g of material was recovered, which comprised: pyrimidine (2.7%), 2-methyl piperidine (18.1%), N-ethyl piperidine (2.6%), methyl pyrazine (4.5%), 2,5-dimethyl pyrazine (2.3%), ethyl pyrazine (1.2%), 2-ethyl-3-methyl pyrazine (1.5%), trimethyl pyrazine (2.5%), N-ethyl-2- pyrrolidinone (1.3%), 2-piperidinone (5.1%), 2-methyl cyclopent2-en-l-one (1.6%), condensed pyrazines (5.1%) and numerous unidentified components.

[00127] The aqueous mixture of the sample heated to 300 °C with 1.86 g CuO gave 0.38 g of extractible oil, comprising: N-methyl pyrrole (2.8%), pyridine (2.9%), methyl pyrazine (4.9%), 2,5- dimethyl pyrazine (3.9%), ethyl pyrazine (2.2%), 2-ethyl-3-methyl pyrazine (3.3%), ethyl-methyl pyrazine (0.9%), trimethyl pyrazine (4.4%), cyclopentanone (0.8%), 2-methyl cyclopent2-en-l-one (2.7%), 2,3-dimethyl cyclopent2-en-l-one (1%), trimethyl hydantoin (1.1%), 2-piperidinone (3.5%), condensed pyrazines (4%) and numerous unidentified components. After acidification to pH 1, 0.25 g of material was recovered, which contained : 2-methyl propionic acid (7%), butanoic acid (23.3%), 2-methyl butanoic acid (8.8%), 3-methyl butanoic acid (4%), pentanoic acid (4.7%), 4-methyl pentanoic acid (13.4%), pyrimidine (0.8g), ethyl pyrazine (0.8%), 2,3-dimethyl cyclopent-2-en-l-one (0.3%), 2-piperidinone (6.9%), and numerous unidentified components. After adjusting the pH to 14, 0.3g of material was recovered, which comprised: pyrimidine (2.7%), 2-methyl piperidine (18.1%), N-ethyl piperidine (2.6%), methyl pyrazine (4.5%), 2,5-dimethyl pyrazine (2.3%), ethyl pyrazine (1.2%), 2-ethyl-3-methyl pyrazine (1.5%), trimethyl pyrazine (2.5%), N-ethyl-2- pyrrolidinone (1.3%), 2-piperidinone (5.1%), 2-methyl cyclopent2-en-l-one (1.6%), condensed pyrazines (5.1%) and numerous unidentified components

[00128] The aqueous mixture of the sample heated to 300 °G with 3.6 g CuO gave 0.35 g of extractible oil, comprising: pyrimidine (3.3%), methyl pyrazine (4.7%), 2,5-dimethyl pyrazine (2.8%), ethyl pyrazine (1%), 2-ethyl-3-methyl pyrazine (3.3%), trimethyl pyrazine (3.8%), cyclopentanone (0.9%), 2-methyl cyclopent2-en-l-one (2.8%), 2,3-dimethyl cyclopent-2-en-l-one (1%), trimethyl hydantoin (0.8%), N-(3-methylbutyl)acetamide (4.2%), 2-piperidinone (4.3%), condensed piperazinedione (3.6%), condensed pyrazines (6.2%) and numerous unidentified components. After acidification to pH 1, 0.59 g of material was recovered, which contained : 2-methyl propionic acid (5%), butanoic acid (15%), 2-methyl butanoic acid (5.4%), 3-methyl butanoic acid (3.6%), pentanoic acid (3.8%), 4-methyl pentanoic acid (11.9%), 2-methyl-3-ethyl pyrazine (2.3%), N-methyl succinimide (1.1%), 2 r piperidinone (7.5%), and numerous unidentified components. After adjusting the pH to 14, 0.2g of material was recovered, which comprised: pyrimidine (1%), 2-methyl piperidine (27.3%), methyl pyrazine (3.6%), 2,5-dimethyl pyrazine (1.9%), ethyl pyrazine (0.7%), trimethyl pyrazine (1.7%), N-ethyl-2-pyrrolidinone (0.7%), 2-piperidinone (6.3%), condensed pyrazines (4.1%) and numerous unidentified components. Example 12 Magnesium oxide

[00129] A slurry of 18.6 g of microalgae together with 13.5 g of magnesium oxide was heated to 330 °C, and held for 30 minutes at the reaction temperature, then cooled and filtered. The fluid was extracted with methylene chloride, to give 3.65 g oil that comprised: dimethyl disulphide (1.1%), toluene (3.7%), ethyl benzene (3.8%), styrene (4.7%), methyl pyrazine (3.8%), 2,5-dimethyl pyrazine (2.8%), trimethyl pyrazine (4%), 2-piperidinone (4%), 3-methyl indole (2.4%), pentadecene (2.8%), heptadecene (1.2%), heptadecane (3.2%), alkenes, MW 280 (11.8%) hexadecanamide (1%) and numerous unidentified compounds.

[00130] The aqueous organic fraction (3.92 g) gave volatiles that passed through a gas chromatograph of composition: cyclopentanone (0.5%), acetic acid (13.5%), 2-methyl propionic acid (4.8%), butanoic acid (19.7%), 2-methylcyclopent-2-enone (1.4%), 2,3-dimethylcyclopent-2-enone (0.9%), 2,5-dimethylpyrazine (2.4%), trimethylpyrazine (3.8%) and numerous unidentified compounds.

Example 13 Antimony oxide [00131] A slurry of 8.6 g of microalgae together with 1.8 g of antimony oxide (Sb 2 0 3 oxide was heated to 350 °C and to 400 °C , each reaction being held for 30 minutes at the reaction temperature, then cooled and filtered. The fluid was extracted with methylene chloride, then the aqueous solution was acidified to pH 1, and further extracted with methylene chloride. GCMS analysis of the methylene chloride extracts gave (as per centages of that extract that volatalized properly). [00132] In the subcritical reactions the oil (6.18 g) comprised: dimethyl disulphide (5.6%), toluene (2.6%), xylene (5.5%), styrene (2.1%), 2,3-dimefhyl cyclopent-2-en-l-one (1.2%), trimethyl pyrazine (3.6%), N-ethyl-2-pyrrolidinone (1.3%), pentadecene (2.9%), pentadecane (1%), heptadecene (2.1%), heptadecane (1.2%), tetramethyl-hexadec-2-ene (3.4%), hexadecanoic acid (1.5%), hexadecanamide (2.1%), octadec-9-enamide (2.7%), and numerous unidentified compounds. . [00133] The aqueous fraction (1.3g) contained acetic acid (13.6%), propanoic acid (<5.2%), 2- methylpropanoic acid (3.4%), butanoic acid (6.7%), pentanoic acid (5%), butanamide (3.5%), 2- pyrrolidinone (3.6%), 2-piperidinone (<8%), hexadecanoic acid (0.9%), oleic acid (0.4%), and numerous unidentified compounds.

[00134] In the supercritical reactions the oil (8.25 g) comprised: dimethyl disulphide (1.2%), toluene (2.2%), ethyl benzene (3.8%), 2,3-dimethyl cyclopent-2-en-l-one (1.4%), methyl phenols

(3.5%), dimethyl phenols (4.1%), 2-methyl pyrazine (1.6%), 2,5-dimethyl pyrazine (1.5%), trimethyl pyrazine (2.1%), N-methyl-2-pyrrolidinone (4.4%), N-ethyl-2-pyrrolidinone (2.2%), N-butyl-2- pyrrolidinone (3.9%), 2-piperidinone (4.8%), indole (1.1%), pentadecene (1.3%), pentadecane (1%), heptadecene (2.3%), heptadecane (1.2%), hexadecanoic acid (3.3%), hexadecanamide (2.2%), methyl octadec-9-enoic acid (1.2%), and numerous unidentified compounds. ' [00135] The aqueous fraction (0.7g) contained acetic acid (12.3%), propanoic acid (3.9%), 2- methylpropanoic acid (3.4%), acetamide (4.4%), butanamide (3.6%), N-methyl-2-pyrrolidinone (4.1%), 2-pyrrolidinone (5.4%), 2-piperidinone (8.8), and numerous unidentified compounds

Example 14 Zirconium dioxide

[00136] A slurry of 18.6 g of microalgae together with 0.9 g of titanium dioxide was heated to 350 °C for the subcritical reaction, 400 °C for the supercritical reaction, held for 30 minutes at the reaction temperature, then cooled and filtered. The fluid was extracted with methylene chloride when the subcritical reaction gave an oil yield of 6.59 g, the aqueous fraction giving 1.87 g of organic material, while the supercritical reaction gave 6.32 g oil, the aqueous fraction giving 0.69 g of organic material. GCMS analysis of the methylene chloride extracts gave (as per centages of that extract that volatalized properly):

[00137] In the subcritical reactions: ethyl benzene (2.3%), styrene (1.7%), 2,5-dimethyl pyrazine (2.1%), trimethyl pyrazine (2.7%), 2-piperidinone (4.5%) pentadecene (4.1%), heptadecane (1.9%), hexadecanoic acid (5.7%), oleic acid (1.8%), hexadecanamide (2.2%), 9-octadecenamide (1.8%) and numerous unidentified products. [00138] The aqueous fraction gave an extract containing acetic acid (18.3%), propanoic acid

(5.9%), 2-methyl propanoic acid (6.6%), butanoic aicd (19.3%), 4-methyl pentanoic acid (6.5%), and numerous unidentified products.

[00139] In the supercritical reactions: toluene (4.1%), ethyl benzene (5.9%), trimethyl pyrazine (2%), 2,3-dimethylcyclopent-2-en-l-one (1.6%), 2-piperidinone (6.1%), N-butyl 2-pyrrolidinone (5.1%). 3-methyl indole (1.9%), m-ethylphenol (3.1%) pentadecene (3%), probably pentadecane (3.9%), heptadecane (2.6%), hexadecanoic acid (2.8%), hexadecanamide (2.4%), and numerous unidentified products.

[00140] The aqueous fraction gave an extract containing acetic acid (11%), propanoic acid (3.3%), butanoic aicd (3.6%), 4-methyl pentanoic acid (2.1%), benzenepropanoic acid (3.8%), acetamide (5.5%), N-methyl acetamide (<9.7%), butanamide (3%), N-methyl-2-pyrrolidinone (4.2%), 2-piperidinone (6.8%), and numerous unidentified products. Example 15 Iron sulphide

[00141] A slurry of 18.6 g of microalgae together with 1.25 g of iron sulphide was heated to 350 °C for the subcritical reaction, 400 "C for the supercritical reaction, held for 30 minutes at the reaction temperature, then cooled and filtered. The fluid was extracted with methylene chloride when the subcritical reaction gave an oil yield of g, the aqueous fraction giving g of organic material, while the supercritical reaction gave 5.2 g oil, the aqueous fraction giving 0.6 g of organic material. GCMS analysis of the methylene chloride extracts gave (as per centages of that extract that volatalized properly):

[00142] In the supercritical reactions the oil comprised: toluene (2.1%), ethyl benzene (5.2%), 3- methyl cyclopent-2-en-l-one (1.1%), 2,3-dimethyl cyclopent-2-en-l-one (1.7%), methyl pyrazine

(1.8%), 2,5-dimethyl pyrazine (1.9%), trimethyl pyrazine (2.1%), N-methyl-2-pyrrolidinone (6.2%), N-ethyl-2-pyrrolidinone (3.8%), 2-piperidinone (5.1%), N-butyl-2-pyrrolidinone (4.4%), indole (3.1%), 3-methyl indole (1.7%), pentadecene (2.6%), pentadecane (2.7%), heptadecane (1.5%), 2- heptadecanone (0.9%), hexadecanamide (0.9%), and numerous unidentified compounds. INDUSTRIAL APPLICATION

[00143] The method of the invention may be used to produce:

(a) materials such as aromatic hydrocarbons, linear alkanes and alkkenes, and lighd oxygenated volatile hydrocarbons able to be used direcdy as additives to fuel,

(b) material which may be refined by processes such as hydrotreating and cracking as known to those practised in the art to make fuels,

(c) chemical products which may act as feedstock for other chemicals,

(d) pyrazines that may be used direcdy as flavour enhancers,

(e) polymethylated pyrazines that may be oxidized to make diacids suitable for biopolymers, particularly hydrophilic biopolymers.

(f) diols that may be used to make hydrophilic biopolymers such as polyesters,

(g) ethyl benzene, which would be a bioprecursor to styrene, or styrene itself, which permits a renewable sopurce of polystyrene, and related polymers such as an unsaturated polyester component, an ABS component, etc.

[00144] The foregoing description of the invention includes preferred forms thereof.

Modifications may be made thereto without departing from the scope of the invention.