for

ENERGY GENERATING PROCESS AND NOVEL FUEL THEREFOR

Field of the Invention

This invention relates to a process for generatin energy in a furnace or combustion engine which comprises burning in said furnace or said combustion engine the novel alcohol-soluble portion of the product obtained as a result of the mild reaction of a lignin-containing material with nitric acid. This invention additionally relates to said alcohol-soluble portion of said product itself as a new fuel and to a novel fuel composition containing said alcohol-soluble portion.

Description of the Prior Art

Lignin-containing materials, such as peat and wood, are available in large amounts and are known to have fuel value since they are susceptible to combustion. However, since their fuel value is comparatively low, their use is

generally limited to heating applications and steam generation. It would be highly desirable, therefore, to render such lignin-containing materials more attractive as fuels, or as components of fuels, and to enlarge on their considerable potential as an energy source.

Summary

I have discovered that lignin-containing materials can be upgraded as fuels and fuel additives and their utilization, therefore, can be greatly extended by subjecting the same to a mild reaction with nitric acid and recovering as said novel fuel, or fuel additive, the alcohol-soluble portion of the nitric acid reaction product so obtained for use in generating energy in a furnace or a combustion engine.

By a "lignin-containing material," I mean to include any material the includes in its normal state at least about five weight percent lignin, generally at least about ten weight percent lignin. As an example, on a water-free basis, the lignin-containing material can contain from about five to about 100 weight percent lignin, generally from about 20 to about 100 weight percent lignin. By lignin I mean a high molecular derivative of phenyl-propane, wherein the phenyl groups are substituted with one to two methoxy groups and the propane side chains with hydroxyl groups. The phenyl-propane units are linked with each other from the side chain to the nucleus partially by carbon-to-carbon, partially by either linkages. (Reference: Lignin Structures and Reactions, Advances in Chemistry, Series #59, American Chemical Society publications #59) . Remaining organic material associated with the lignin-containing material can be cellulose, hemicellulose, bitumen, humic acid, etc. The lignin-containing material in its normal state usually contains large amounts of water; for example, from about 0 to about 95 weight percent, generally from about 20 to about 95 weight percent water. Examples of lignin-containing

materials that are particularly attractive for use herei include peat, wood, biomass, such as bagasse and lignin etc. Peat is the particularly decomposed residue of dea plants and animal microorganisms associated with about 80-9 weight percent of water.

The novel fuel defined and claimed herein for use i generating energy in a furnace or combustion engine i easily obtained by subjecting the above-define lignin-containing material or mixtures of lignin-containin materials to a mild reaction,, with nitric acid and the recovering from the nitric acid reaction product th alcohol-soluble portion thereof. Thus, nitric acid can b added to the above-defined lignin-containing material, whil stirring the mixture, until the reaction of the nitric aci with the lignin-containing material has continued to th extent desired. During the reaction water and nitroge oxides produced, and any other volatile materials that ma result from the reaction, are permitted to escape. Soli reaction product obtained is then subjected to extractio with an aliphatic alcohol or mixtures of aliphatic alcohol having from 1 to 10 carbon atoms, particularly from 1 to carbon atoms. These include methanol, ethanol, norma propanol, isopropanol, butanol, decanol and mixtures of th lower alcohols such as those obtained in the industria production of fuel grade methanol and ethanol. If desired any suitable polar solvent, for example, such as define hereinafter can also be used as an extractant.

The conditions that can be used above in subjecting th lignin-containing material to reaction with nitric acid mus be mild. The reaction can be carried out using an aqueou mixture containing the lignin-containing material an aqueous nitric acid. The nitric acid used can have concentration of about 5 to about 100 weight percent nitric aciά, preferably about 15 to about 70 weight percent nitric acid. The mixture can contain about 0 to about 95 weigh percent water, preferably about 40 to about 80 weigh

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percent water. On a weight basis, the lignin-containing material (on a dry basis) and the nitric acid (as 100 percent nitric acid) can be in the range of about 1:0.1 to about 1:10, preferably about 1:1 to about 1:2. The above is mixed while it is maintained in a temperature range of about -10° to about 150°C, preferably about 20° to about 100°C, and a pressure of about 14.5 to about 1000 pounds per square inch gauge, preferably about 14.5 to about 100 pounds per square inch gauge, for about 1 minute to about 10 hours ^' , preferably about 0.5 to about 2. hours. The resulting reaction product is then subjected to extraction with any suitable polar solvent, for example, a ketone, such as acetone, methylethylketone, cyclohexanone, etc. , an alcohol, such as methanol, ethanol, normal propanol, isopropanol, butanol, decanol, and mixtures of the lower alcohols such as those obtained in the industrial production of fuel grade methanol and ethanol, etc., tetrahydrofuran, dioxane, etc., or mixtures thereof. The extraction can be carried out at temperatures in the range of about 0° to about 200°C and the extraction can be continued until no further extract is obtained. Removal of polar solvent from the extract can be effected by subjecting the extract to drying or distillation. The solid material obtained is the novel alcohol soluble product herein.

If desired, the procedural steps defined in U.S. Patent No. 4,052,448, dated October 4, 1977, of Schulz et al. , can be used in reacting the lignin-containing material with nitric acid, provided the reaction parameters defined above are maintained.

The nitric acid reaction product obtained above, as the novel fuel herein, contains both water-soluble and water-insoluble components. The water-soluble components will be in the range of about 10 to about 95 weight percent, generally about 40 to 70 weight percent. I have found that since the lignin-containing materials, as defined herein, contain phenyl groups with a large number of aliphatic

chains linking the same to each other, under the mil reaction conditions defined above, cleavage within th molecule is easily effected by oxidation, without resultan decarboxylation, and nitration also occurs to varyin extents. The resultant reaction product so obtained thu has a molecular weight substantially lower than th lignin-containing material that was subjected to reactio with nitric acid and now additionally carries carboxyl an nitro groups.

The nitric acid reaction product obtained abov-e can b used as such in a conventional manner for generating energ in a furnace or a combustion engine by burning the sam therein. Combustion engines that can be used includ internal combustion engines, such as a Diesel engine, or turbine, or an external combustion engine, such as a stea engine. Alternatively, the product can be used to prepare novel fuel composition for use in a furnace or a combustio engine. In one embodiment, the product can be dissolved i an alcohol, such as methanol, ethanol, mixtures thereof an mixtures of lower alcohols such as those obtained in th industrial production of fuel-grade methanol or ethano wherein, the reaction product can amount to about 3 to abou 95 weight percent, preferably about 25 to about 75 weigh percent, of the final solution, with the remainder being th alcohol used. This solution, which will be discusse further below, is an excellent Diesel fuel. Alternatively a slurry can be prepared that includes the nitric aci reaction product and a hydrocarbon fuel wherein the nitri acid reaction product can amount to about 5 to about 9 weight percent, preferably about 30 to about 80 weigh percent, of the final product. By "hydrocarbon fuel," mean to include liquid hydrocarbons, such as petroleu fractions, oils resulting from coal liquefaction or othe coal conversion processes, the extract from oil shale an tar sands, liquids resulting from the pyrolysis of organi matter, etc. Additionally, a slurry can also be prepare

that includes the nitric acid reaction product and up to 30 percent, preferably 20-25 percent, of water.

As pointed out above, the solution of methanol, ethanol, mixtures thereof, and mixtures of lower alcohols, such as fuel-grade methanol and fuel-grade ethanol with the nitric acid reaction product results in an unexpectedly well performing Diesel fuel. In order for a material to be effective when incorporated into an alcohol for a diesel fuel, it must produce satisfactory ignition promotion, have excellent solubility in the alcohol and equally- important possess viscosity and lubricity properties close to or equivalent to those of conventional petroleum-derived diesel fuel. I have found that the nitric acid reaction product defined herein, when added to one of the defined alcohols, will result in a Diesel fuel having all of the defined desired properties.

I have found, for example, that the product obtained when peat is subjected to a mild reaction with nitric acid, as defined above is infinitely soluble in the alcohols defined immediately, above. This is believed to result from the presence of a large number of aliphatic substituents in the peat and carboxyl groups in the resulting reaction product. Additionally, liquidity of the solute at injector nozzle temperatures is highly desirable, particularly in a "solution-type" Diesel fuel, since solvent evaporation, after engine shut-off, can leave behind solid residues, especially in the fuel injector, resulting in problems to restart the engine. Since the product containing the defined alcohol, for example, methanol, and nitric acid reaction product, possesses viscosities (for example, 7 centipoise at 25°C) and lubricity close to those of conventional Diesel fuels, it can be injected with standard injection systems. High viscosities and lack of sufficient lubricity are undesirable, for Diesel fuels having such characteristics can cause wear of pump elements, resulting engine failure. On the other hand, no mechanical problems

were encountered with the novel fuels herein. That th nitric acid reaction product defined herein is a goo ignition promoter is shown by the fact that the product containing equal amounts by -weight of methanol and th alcohol-soluble portion of the nitric acid reaction product using peat as the lignin-containing charge material hav ignition delays comparable to good Diesel fuels with cetane number of 52. Essentially smoke-free emissions reduced nitric oxide production compared to conventiona

Diesel fuels and an increase in power- output over methano alone were consistently observed.

The above results are surprising. When coal or lignit are subject to reaction with nitric acid, for example, as i

U.S. Patent No. 4,052,448 to Schulz , et al., referred t above, or in U.S. Patent No. 4,278,443 to Beuther et al. substantially all of the organic reaction product obtaine is water-insoluble, whereas herein generally at least abou

50 weight percent is water soluble. The water-solubl product obtained in said patents has no ignition propertie at all of its own when added to methanol, for example, fo use in a diesel engine. Not only is the novel fue composition herein characterized by the fact that generall more than half of it is water-soluble, but that when adde to an alcohol, for example, methanol, all of its component including its water-soluble portion, are excellent ignitio promoters therein. Therefore, the use of an extraneous ignition promoter, such as an alkyl nitrate (for example, octyl nitrate) , is not required. Infinite solubility of th nitric acid reaction product of peat in the alcohol, for example, methanol, and desired viscosity, lubricity and liquidity properties of the resulting solution when used in

Diesel engine, are lacking in the comparable product when using the nitric acid reaction product of the Schulz, et al., and the Beuther et al. , patents referred to above.

When the lignin-containing material used herein to make the novel fuel is peat and the nitric acid reaction product

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is subjected to extraction with one of the polar solvents defined above, for example, methanol, most of the contaminants that were in the original peat remain in the insoluble residue and the extract contains only small amounts of polar solvent-soluble metal contaminants. These contaminants can be removed from the extract by any suitable means, for example, by treating the same with an ion-exchange resin, such as "Amberlyst 15" acid ion exchange resin. ~ ^" —=-

Description Of Preferred Embodiments

A number of reactions was carried out as follows. Aqueous nitric acid was added to Finnish high humification peat uniformly over a period of 0.75 hours while the mixture was agitated. While the resulting mixture was stirred, it was maintained at selected temperatures and ambient pressure for two hours after the nitric acid addition. At the end of the reaction period, residual water was removed from the reaction product by evaporation, and the dry reaction product remaining was extracted exhaustively with methanol at ambient temperature and ambient pressure. The methanol extracts thus obtained were then evaporated for the recovery of methanol-soluble reaction product (MSP) , which contained both water-insoluble components and water-soluble components. The relative amounts of water-insoluble components and water-soluble components present were determined by extracting the total solids with water. In Table I, the reactions were each carried out at 85°C and the weight ratio of nitric acid to peat was varied. The results obtained on analysis of the reaction product are tabulated in Table I.

TABLE 1

n No. O /Peat Weight Ratio 0.25:1 0.5:1 1:1 2.1 oduct Analysis % Selectivity NE* % Selectivity NE* % Selectivity NE* % Selectivity N termediates Plus Ash 75.0 248 61.5 256 28.0 250 16.3 1 ter-Insoluble MSP 14.0 215 18.0 219 31.0 149 28.8 1 ter-Soluble MSP 13.0 138 20.9 138 35.0 110 47.0 tal MSP 27.0 38.9 66.0 75.8 tio of Water-Insoluble 1. 1 0, ,9 0. ,9 0.6 SP to Water-Sol uble MSP

In Table I, as elsewhere, "NE" designates the neutral equivalent of the fraction referred to and "Intermediates Plus Ash" refers to the partially reacted residual product and contaminants. Note that nitric acid to peat ratios have a pronounced effect on peat conversion and the ratio of water-insoluble to water-soluble components produced. In all cases, the water-soluble components were present in at least the same amount as the water-soluble components but generally much higher.

In Table II, the comparable effects of nitric acid to peat ratios were studied at different temperatures.

TABLE II

n no O^/Peat Weight Ratio 1 1::11 1 1::11 2:1 2.1 mperature, °C 8 855 5 500 50 85 roduct Analysis % % SSeelleeccttiivviittyy N NEE % % S Seelleeccttiivviittyy N NEE % Selectivity NE % Selectivity N ntermediates Plus Λsh 2 288..00 2 25500 2 288..44 2 21144 19.1 216 16.3 1 ater-Insoluble MSP 3 311..00 1 14499 3 322..33 1 16611 30.0 169 28.8 1 ater-Soluble MSP 3 355..00 1 11100 3 366..11 1 10055 53.8 94 47.0 otal MSP 6 666 6 688..44 83.8 75.8

1 atio of Water-Insoluble 0 0..99 0 0.. .99 ,0. .6 0.6 MSP to Water-Soluble MSP

In Table II, it can be seen that variations in temperature from 50° to 85°C have little effect on the amount of product obtained and on product distribution.

The data in Table III show the effect of temperature on the reaction, product obtained wherein the nitric acid to peat ratio was maintained at 1:1.

TABLE 111

o. 9 10 11 12 13 rafmi _' , °C 25 35 50 65 85 ct Analysis % Selectivity NE % Selectivity NE_ % Selectivity NE % Selectivity NE % Selectivity NE inediatcK Plus Ash 47.4 226 37.3 213 28.4 214 35.0 246 28.0 250 -Insoluble MSP 29.7 163 38.1 149 32.3 161 33.0 163 31.0 149 -Soluble MSP 30.0 125 33.0 95 36.1 105 36.0 102 35.0 110 I MSP 59.7 77.1 68.4 69.0 66.0 of Water-Insoluble 1 1,2 0.9 0.9 0.9 1 to .nt- i -Soluble MSP )

The data in Table III shows that while the temperature is rate determining it has hardly any effect on product distribution.

In Table IV results from peats of different humification, high, medium, and low, are tabulated. Humification levels signify age of peat and corresponding degrees of decomposition. The nitric acid to peat weight ratio was 1:1 and the reaction temperature 50°C.

TABLE IV

υn No. 14 15 16 umification High Medium Low oduct Analysis % Selectivity NE % Selectivity NE % Selectivity NE ntermediates Plus Ash 28.4 214 35.5 189 26.6 17 ater-Insoluble MSP 32.3 161 21.7 147 18.8 14 ntor-Soluble MSP 36.1 105 34.9 99 47.2 11 otal MSP 68.4 56.6 66 atio of Water-Insoluble 0.9 0.6 0.4 1 MSP to W ter-Soluble MSP

Ln I

Results with peat of various age differ mainly in product distribution. Older, high humification peat will give about equal amounts of water-insoluble and water-soluble components . Products from low humification peat predominates in the water-soluble components. In all cases the reaction product obtained from all peats appear to be similar as evidenced by their neutral equivalent and solubility in methanol. Analysis of the methanol-soluble product from Run No. 14 is typical. This is shown below in

Table V.

TABLE V

Weight Percent

Carbon 45.26

Hydrogen 5.08

Nitrogen 3.23

Sulfur 1.84

Oxygen 43.81

Ash 0.78

Hydrogen to Carbon Rat:io 0.11

Run No. 17

In this run Finnish Peat was used. Aqueous nitric acid having a concentration of 70 weight percent was used and added to the peat over a two-hour period, followed by a two-hour hold period all at 50°C. Weight ratio of nitric acid (as 100 percent nitric acid) to peat was 1:1. No water was used as diluent. The air-dried peat charge contained a mixture of peats of high, medium and low humification with varying moisture content. The dried products were slurried at ambient temperature with sufficient amounts of methanol to permit their removal from the reactor flask. The slurries were filtered and re-extracted with methanol to generate methanol-soluble

reaction products. Methanol-insoluble filter cakes we recycled to the solubilization step alone or along wi fresh peat. Methanol product solutions were evaporated adjust their content of methanol-soluble reaction product 50 weight percent. Moisture content of the products s obtained varied from four to 12 weight percent, with as around three weight percent. Removal of residual meta contaminants was carried out by contacting the methano solutions with "Amberlyst -15" acid ion exchange resin. ^• Th product after this treatment contained 0.42 weight percen ash. Further removal of ash could still be obtained b repeating this procedure. Table VI below sets forth th elemental analysis of the original solid nitric aci reaction product.

TABLE VI

Weight Percent

Carbon 49.0

Hydrogen 4.9

Nitrogen 3.7

Sulfur 0.5

Oxygen 39.6

Ash 2.4

Neutral Equivalent 119

BTU/Pound 7718

Viscosities of the 50 percent by weight methanol solution are given below in Table VII.

TABLE VII

Temperature, °C Centipose

-9.9 66

0 36.6

10.1 21.5

25.2 - 13.2

40 - - 5.3

BTU/Pound 7266

Run No . 18

A Diesel fuel was prepared containing 50 weight percent of the total methanol-soluble product obtained in Run No. 14 and 50 weight percent methanol. A series of runs was carried out using one-gallon quantities of the Diesel fuel so prepared to power a CLR Diesel test engine, manufactured by Lab Equipment Corporation of Mooresville, Indiana. In each run the engine was started, with methanol containing about five weight percent of octyl nitrate as ignition promoter and one weight percent of castor oil as lubricant. After about 5 minutes of operation in this mode, injection of the methanol fuel was discontinued and operation was continued using the novel Diesel fuel prepared above. In each case, operation was continued over a period of 30 minutes until the fuel was exhausted. In each case where the test fuel was used the engine ran smoothly, with a power output in excess of the power output using methanol alone. No visible emissions of particulates were noted.

Obviously, many modifications and variation of the invention, as hereinabove set forth, can be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.