Field

The present disclosure relates to the use of a carbonaceous material, which has been produced via a process comprising heating of a compound comprising carbon, oxygen and hydrogen under non-oxidative conditions at a temperature of at least about 700 °C. The material finds particular use in electrodes, which may be incorporated into a variety of energy storage, energy conversion and energy generation devices. The material is also well-suited for use as an absorbent, in particular for gases such as hydrogen.

Background

In all fields of technology, scientists are constantly striving to provide environmentally friendly alternatives to existing products and processes. For instance, one way of dealing with waste matter from a variety of sources is burning. However, burning of waste matter containing carbon generates carbon dioxide, which is of course highly undesirable. The traditional burning of materials comprising carbon, for instance biomass and in particular agricultural waste, emits large amounts of carbon dioxide into the atmosphere, which of course contribute to the greenhouse effect in the atmosphere. Natural decomposition of such materials can also generate carbon dioxide and, thus, also has a negative effect upon the environment. Scientists have therefore researched ways of limiting, and ideally neutralising, the negative effects of carbon-containing waste materials such as biomass upon the environment.

The treatment of carbon-containing materials in controlled atmospheres has been known for centuries. For instance, evidence exists that the heating of wood and other carbon-containing materials under non-oxidative conditions, eg. in the absence of oxygen, or in oxygen-limited environments to form carbonaceous materials, including those commonly termed "char" and "charcoal", was carried out in ancient times. There is also evidence that ancient Amazonians produced a carbonaceous material, now commonly termed "biochar", from heating biomass in the absence of oxygen, and used the product to enhance soil productivity. In fact, "biochar" is widely used for this purpose today, and is a very effective way of reducing the impact of carbon-containing waste upon the environment, as it can sequester carbon in the soil for many hundreds of years. Processes involving heating carbon-containing materials such as biomass, can be labelled according to the amount of oxygen supplied to the reaction system. The extent to which feedstock materials will burn depends upon the equivalent ratio of the number of moles of oxygen fed to the reactor in comparison with the equivalent number of moles of carbon in the product being subjected to the heating process. Thus, if the equivalent ratio is zero, ie. there is no oxygen in the reactor, the process is often termed a "pyrolysis" process. If the equivalent ratio is less than about 0.15, such processes are generally termed "pyrolytic gasification" or "flaming pyrolytic gasification"; whereas, if the equivalent ratio is about 0.15 to about 0.3, such processes are typically known as "gasification" in the art.

Pyrolysis has been identified as a promising technology for the production of stable carbon for sequestration, ie. carbon provided in the form of "biochar", and bio-oil or pyrolysis oil, for some time. See Bridgwater and Peacocke, "Fast Pyrolysis Processes for Biomass", Renewable and Sustainable Energy Reviews, Volume 4 (1), pp. 1-73, 2000, for instance. Gas, specifically a mix of carbon monoxide, carbon dioxide and hydrogen, will also be produced from the pyrolysis process. Furthermore, if the process focusses upon maximising the yield of charcoal or biochar, it is conventionally known as "carbonisation".

The distribution of gas, liquid and solid products from such heating processes has been found to be highly dependent upon the feedstock and operating conditions. A summary of thermochemical conversion technologies is shown in Table 1. The information in Table 1 is taken from "Biochar for Environmental Management, Science, Technology and Implementation", edited by J Lehmann and S Joseph and published by Routledge (Abingdon, U K) in 2015.

Thermochemical Temperature Major Intended Product(s) &

Gas % Liquid% Solid%

Process (°C) Use(s)

Pyrolysis (for Biochar: soil amendment,

300-700 40-75 0-15 20-50

biochar) carbon sequestration

Syngas: gaseous fuel for heat &

Gasification 500-1500 85-95 0-5 5-15

power; and gas to liquid

Hydrothermal

200-400 0-90 0-80 0-60 Various chemical products processing

Energy converted to heat &

Combustion 1000-1500 95 0 5

power

Table 1

Furthermore, even within the umbrella of "pyrolysis" of biomass for instance, there are different types of pyrolysis processes, which are typically defined by their pyrolysis temperature, biomass heating rate, reaction time and added chemicals (for example hydrogen or water). The different types of pyrolysis processes are shown in Table 2. This information is derived from Tripathi, Sahu and Ganesa, "Effect of Process Parameters on Production of Biochar from Biomass Waste through Pyrolysis: A Review", Renewable and Sustainable Energy Reviews, pp. 467-481, 2016.

Table 2 Slow pyrolysis is the conventional pyrolysis process characterised by a slow heating rate and long reaction time. It is still considered in the art to be the pyrolysis process which is most favourable to the yield of biochar, and it is the process used in the majority of biochar- focussed production facilities. A small amount of pyrolysis oil and gases is also produced in this process. However, the major drawback of this technology is the long reaction time, which can be 50 times higher than fast pyrolysis. This severely reduces the production output rate of a biochar facility. As mentioned above, biochar produced by such processes currently finds use in a range of applications encompassing soil improvement, improved resource use efficiency, remediation and/or protection against particular environmental pollution, as well as providing an avenue for greenhouse gas mitigation. In particular, biochar has been found to significantly enhance the crop yield of soils, as it provides a favourable habitat for many beneficial soil microorganisms and its porous structure is very effective at retaining water and water-soluble nutrients, for instance.

For a material to be recognised as "biochar", it must meet a number of material property definitions, which relate both to its value, for instance its hydrogen/organic carbon (H/C _or g) ratios relate to the degree of charring and therefore mineralization in soil; and to its safety, for instance its heavy metal content. The requirements of biochar have been identified by the International Biochar Initiative (IBI; http://www.biochar-international.org), which is an international organisation promoting good industry practices, stakeholder collaboration, and environmental and ethical standards to foster economically viable biochar systems, which are both safe and effective for use in soil fertility and as a climate mitigation tool.

It is further noted that the terms "biochar", "char" and "charcoal" each describe products of the pyrolysis, ie. heating, or more specifically thermochemical degradation, in the absence of oxygen, of carbon-containing waste materials, in particular biomass. These products are thus commonly known as "pyrogenic carbonaceous materials" (PCMs). Whilst the three terms can be quite loosely applied in the art and can, therefore, seem freely interchangeable, they do refer to the products of different processes. In particular, "char" typically refers to residue from natural fires; "charcoal" typically refers to products of pyrolysis of animal or vegetable matter in kilns for cooking or heating purposes, including industrial applications such as smelting; and "biochar" is the term given to pyrogenic carbonaceous materials typically produced by heating biomass in the absence of, or with limited, air to a temperature above about 250°C up to 700 °C, which are specifically provided for application to soil for agronomic or environmental management. In some instances, the material properties of biochar may overlap with those of charcoal as an energy carrier. However, many types of biochar do not easily burn, and charcoals are typically not made to address soil issues. These differences are discussed in Lehmann J and S Joseph (2015). However, irrespective of their given name or the specific nature of their production, it is clear that carbonaceous materials made from processes comprising heating under non-oxidative conditions are environmentally advantageous and possess a number of beneficial properties, which render them extremely useful in a number of applications. In view of their beneficial nature, it would be desirable to try to increase the number of areas where such carbonaceous materials can be effectively used, and to diversify those areas.

Summary

Accordingly, a first aspect is directed to an electrode comprising a carbonaceous material, which material has been produced by a process comprising heating of at least one compound comprising carbon, oxygen and hydrogen under non-oxidative conditions at a temperature of at least about 700 °C. The electrode may be incorporated into an energy storage device such as a battery, a capacitor or a supercapacitor, or an energy generation or energy conversion device such as a fuel cell or an electrolyser. The use of such a carbonaceous material in an electrode is also provided.

A further aspect provides a carbonaceous material, which is the direct product of a process comprising heating of at least one compound comprising carbon, oxygen and hydrogen under non-oxidative conditions at a temperature of at least about 700 °C is used an absorbent, for instance in gas absorption or in the absorption of species from liquids. The carbonaceous material may be incorporated into a gas storage device or into a water treatment device. A system comprising such a gas storage device connected to a fuel cell is also provided.

Further, preferred aspects of the present disclosure are identified in the claims. Brief Description of the Figures

Figure 1 provides a summary of the process, by which carbonaceous material useful in applications described herein is made.

Figure 2 shows X-ray diffraction (XRD) patterns for a carbonaceous material useful in the present disclosure.

Figure 3 is an illustration of the change in morphology of biochar with changes in temperature.

Figure 4 illustrates the correlation between micropore volume and surface area of carbonaceous materials.

Figure 5 shows a comparison of the surface area of a carbonaceous material useful in applications described herein and of various wood-based biochars produced at lower temperatures.

Figure 6 shows a comparison of the volatile matter content of a carbonaceous material useful in applications described herein and of various wood-based biochars produced at lower temperatures.

Figure 7 shows a comparison of the hydrogen to organic carbon molar ratio of a carbonaceous material useful in applications described herein and of various wood-based biochars produced at lower temperatures.

Figures 8 to 10 show the results of electrochemical testing of carbonaceous materials useful in applications described herein and commercially available carbon products.

Detailed Description

A fast process for the production of "biochar" has been identified as providing carbonaceous material, with a number of advantageous characteristics. These properties, which are described in more detail below, have been found to render the carbonaceous material highly suitable for use in a number of applications in which, up until the present disclosure, it has been neither disclosed nor suggested for use. The process comprises heating a feedstock material (hereinafter also, interchangeably, termed "compound") comprising carbon, oxygen and hydrogen (a "C-O-H compound") under non-oxidative conditions at a temperature of at least about 700°C. In the context of the present disclosure, the requirement for "non- oxidative conditions" takes its normal meaning in the art, ie. that the process in carried out in the absence of oxygen and/or other species which would facilitate oxidation of the C-O-H compound. The process, and various modifications thereof, is described in a number of patent applications in the name of Proton Power, Inc., specifically US 2015/0252275 Al, US 2015/0306563 Al and EP-A-2897898, the disclosures of which are incorporated herein by reference. The process is summarised here using a block diagram shown in Figure 1. The process has been designed to produce either syngas or liquid fuel as the main product, while carbonaceous material, termed "biochar", is produced as a by-product.

The process, which is described in the above-listed patent applications as "pyrolysis", operates at a higher temperature than conventional processes used for biochar production, which typically operate at about 300 to 700 °C. More specifically, in the fast pyrolysis process used to provide the carbonaceous material, operating temperatures are at least about 700 °C, and typically in excess of about 700 °C, for instance about 710 °C to about 1500 °C, about 750 °C to about 1500 °C, about 750 °C to about 1400 °C, about 800 °C to about 1250 °C, about 900 °C to about 1250 °C, about 800 °C to about 1100 °C or about 900 °C to about 1100 °C. A particularly effective operating temperature range, in terms of the properties of the resulting carbonaceous material product has been found to be about 1000 °C to about 1100 °C, with about 1050 °C to about 1100 °C being particularly preferred. As such a preferred highest treatment temperature ("HTT") of about 1100 °C is typically observed.

As can be seen from Figure 1, the feedstock comprising one or more C-O-H compounds is first dried to reduce its moisture content typically to about 5 to about 15 % (wet basis; ie. weight % water in the wet material), preferably for instance about 10 % (wet basis), although other moisture contents are also usable. The feedstock can comprise a variety of C-O-H compounds, for example biomass, cellulose, lignin and/or hemicellulose. Preferably the feedstock comprises biomass. The part-dried feedstock is then fed in a reactor. A number of different, conventional types of reactor may be used for the heating process, for instance a screw reactor or a fixed bed reactor. Typically, an auger screw reactor is employed.

As described above, the C-O-H-containing feedstock material is heated to a temperature of at least about 700 °C, and more preferably in excess of about 700 °C, for instance to a temperature in the ranges listed above. As already mentioned, temperatures of about 1000°C to about 1100°C, for instance about 1050 °C to about 1100 °C, are particularly preferred. Upon heating under non-oxidative conditions, the feedstock decomposes into a carbonaceous material (commonly referred to as "biochar"), pyrolysis oil and gases. At this temperature, the pyrolysis oil is in vapour form.

The residence time of the feedstock in the reactor, or the length of time of the heating of the feedstock, typically averages about 0.5 to about 1100 seconds, for instance about 1 to about 1100 seconds, more preferably about 0.5 to about 200 seconds, about 1 to about 300 seconds, about 1 to about 100 seconds, about 1 to about 50 seconds, about 1 to about 25 seconds or about 10 to about 20 seconds, for example. The residence time may be dependent upon the specific operation of the type of reactor being used to carry out the reaction. So, for example, if an auger screw reactor is used, the rotational speed of the auger in the reactor can typically have a bearing upon the residence time of the biomass in the reactor. U nder certain circumstances, the residence time of the C-O-H feedstock in the reactor may have a positive effect in terms of the resulting properties of the carbonaceous material product. Following heating under non-oxidative conditions, the resulting carbonaceous material is conveyed out of the reactor into a storage unit. The vapours from the reaction are fed into a fuel conversion unit and subsequent distillation unit to produce diesel. The by-products of the fuel conversion and distillation processes are water and waste gases, typically a mixture of carbon monoxide, carbon dioxide and hydrogen.

As explained above, the properties of carbonaceous materials produced by this process have been found to render the material particularly suitable for use in a number of different applications. The properties of this material are discussed in the following paragraphs, with reference to the properties of other "biochar" products made by different processes. This comparative information is derived from a number of textbooks and scientific papers, which are referenced below.

As a generality it is firstly noted that, whilst there have been many studies of the physical properties of biochar in anthropogenically produced soils, the pyrolysis process parameters involved appear largely unknown. Reference in this regard is made, for instance, to Glaser et al, "Black Carbon in Density Fractions of Anthropogenic Soils of the Brazilian Amazon Region", Organic Geochemistry, vol, 31, pp 669-678, 2000; Schaefer et al, "Micromorphology and Electron Microprobe Analysis of Phosphorous and Potassium Forms of Indian Black Earth (I BE) Anthrosol from Western Amazonia", Australia Journal of Soil Research, vol. 42, pp. 401-409, 2004; and Chia et al, "Analytical Electron Microscopy of Black Carbon and Microaggregated Mineral Matter in Amazonian Dark Earth", Journal of Microscopy, 2012. Crystal Structure

Carbon-based materials such as coal, charcoal and coke are known to generally exhibit crystalline structure and, typically, turbostratic graphite-based layers. In contrast, X-ray diffraction (XRD) studies have been reported as showing that biochar mostly exhibits amorphous structure rather than crystalline structure. See, for example, Keiluweit et al, "Dynamic Molecular Structure of Plant Biomass-Derived Black Carbon (Biochar)", Environmental Science and Technology, vol. 44, pp. 1247-1253, 2010. In addition, the distribution of crystalline or graphitic structure has been reported as being dependent upon the source of raw material and the carbonisation process. See, for example, McDonald- Wharry et al, "Carbonisation of Biomass-Derived Chars and the Thermal Reduction of a Graphene Oxide Sample studied using Raman Spectroscopy", Carbon, vol. 59, pp. 383-405, 2013.

XRD analysis performed on a Rigaku Smartlab X-ray diffractometer suggests that crystalline structure is found in the carbonaceous material produced by the above-described process, although the signal is not as strong as that observed for a graphite-based material. In more detail, Figure 2 shows the XRD patterns for carbonaceous material produced by the above- described process. The major, broad peaks reveal (002), (100) and (001) planes, which are indicative of the formation of turbostratic carbon crystallites (see Kercher et al., Microstructural Evolution during Charcoal Carbonization by X-Ray Diffraction Analysis", Carbon, Vol 41(1), pp. 15-27, 2003). At temperatures of at least about 400 °C, graphene sheets will typically start stacking progressively. They will arrange in turbostratic disorder and are referred to as "turbostratic crystallites" (Marco et al., "Dynamic Molecular Structure of Plant Biomass-Derived Black Carbon (Biochar)", Environ. Sci. Technol., vol. 44, pp. 1247-1253, 2010). The peaks narrow with increasing temperature. As compared to the XRD peaks of pure graphite (Mochidzuki et al., "Electrical and Physical Properties of Carbonized Charcoals", Ind. Eng. Chem. Res., vol. 42, pp. 5140-5151, 2002), for example, the peaks observed for carbonaceous material useful in the present invention are broader. Therefore, without wishing to be bound by theory, it is suspected that the carbonaceous material used in accordance with the present disclosure comprises a mix of graphitic and non- graphitic carbon, specifically a mix of crystalline and amorphous structure. The formation of crystalline structure is thought to be due to the higher operating temperature of the process. Indeed, it has been reported that, as the highest treatment temperature (HTT) increases, biochar will exhibit higher fractions of crystallinity (see Keiluweit et al, 2010). In addition, it has been observed that higher HTT will increase the growth of polyaromatic crystallite clusters. See, Ronsse et al, "Production and Characterization of Slow Pyrolysis Biochar: Influence of Feedstock Type and Pyrolysis Condition", Global Change Biology Bioenergy, vol. 5, pp. 104-115, 2013.

This is also inferred from the decrease in the hydrogen/organic carbon (H/C _org ) ratio, which has been observed for the carbonaceous material used in accordance with the present disclosure. This is described in more detail below. Typically, the HTT in conventional biochar production does not normally exceed about 600°C. However, as already described, the HTT employed during production of the carbonaceous material useful in applications described herein is most preferably about 1100°C. An illustration of the change in morphology of biochar with changes in temperature is shown in Figure 3 (taken from Lehmann J & Joseph S, 2015). In more detail, Figure 3 shows a comparison of ideal biochar structure development with highest treatment temperature. Sub-figure (a) depicts an increased proportion of aromatic carbon, which is highly disordered, in an amorphous mass; sub-figure (b) depicts growing sheets of conjugated aromatic carbon, which are turbostratically arranged; and sub-figure (c) shows how the structure becomes graphitic with order in the third dimension (see also Emmerich et al 1987).

Surface Area

The surface area of carbonaceous materials, including therefore that of biochar, is linked to its porosity and pore size distribution. The correlation between micropore volume and surface area can be seen in Figure 4, which is taken from Lehmann J and Joseph S, 2015. Porosity is thus thought to be a complex function of one or more of heating temperature, heating rate and heating time. For instance it has been postulated that, during slow pyrolysis of biomass, the aliphatic carbon must first convert into fused ring, aromatic carbon species before porosity can develop. Further, at around 500-600°C, it has been reported that amorphous aromatic C is gradually lost and porosity will start to develop. See Rutherford et al, "Changes in Composition and Porosity occurring during the Thermal Degradation of Wood and Wood Components", US Geological Survey, Scientific Investigation Report 2004-5292, 2004. In addition, porous carbons are typically categorised as either graphitisable carbon or non- graphitisable carbon. See, for instance, Byrne and March, "Porosity in Carbons - Characterization and Applications", Halsted Press, New York, USA, pp. 2-48, 1995. Upon heating to around 800-1000°C, it has been shown that the crystallites of graphitisable carbon will reorient themselves into parallel sheets of carbon atoms, known as graphite, and thus the porosity of the material is destroyed. In contrast, non-graphitisable carbon crystallites are randomly oriented and they are able to preserves porosity. Carbon derived from biomass pyrolysis has been identified as non-graphitisable (Lehmann J & Joseph S, 2015).

It is also known that surface area will increase with an increase in highest treatment temperature. Interplanar distance of aromatic carbon forms decreases with increased ordering. Hence, the surface area per total volume increases (Lehmann J & Joseph S, 2015).

When the applied temperature reaches a certain point, however, it has been reported that structure breakdown occurs and surface area starts to decrease. For example, studies have shown that, for pine biochar produced over a range from 450 to 1000°C, the maximum surface area is generated at a final temperature of around 750°C. See Brown et al, "Production and

Characterization of Synthetic Wood Chars for Use as Surrogates for Natural Sorbents", Organic

Geochemistry, vol. 37, pp. 321-333, 2006.

In relation to carbonaceous material useful in applications described herein, surface area has been found to increase with the temperature of the heating process, or pyrolysis, due to the structural breakdown discussed above, which has been observed as occurring at temperatures of greater than about 700°C. It might be expected that the surface area of the carbonaceous material would not be significantly enhanced in comparison with those of carbonaceous materials made using conventional, lower temperature pyrolysis processes at around 300-600 °C. It might also be expected that the shown mix of graphitic and non- graphitic carbon in the carbonaceous material would also contribute to limiting its surface area. In relation to this, however, Figure 5 shows a comparison of the surface area of a carbonaceous material useful in the applications described herein, which was produced via heating of hardwood from oak trees under non-oxidative conditions at approximately 1100°C, in comparison with values reported for wood-based biochars produced at temperatures between 300 °C and 700 °C. The surface area of the useful carbonaceous material was determined using a butane activity surface area correlation based upon McLaughlin, Shields, Jagiello & Thiele, "Analytical Options for Biochar Adsorption and Surface Area" (2012 US Biochar conference session on Char Characterization). The surface area measurements for the other biochar products were determined via nitrogen adsorption on a BET surface area analyser. The surface area data in Figure 5 for the comparative materials were obtained from "Characterization and Surface Analysis of Commercially Available Biochars for Geo- environmental Applications", I FCEE 2015, San Antonio, TX, March 17-21, 2015; and "Physical and Chemical Characterization of Biochars derived from Different Agricultural Residues", Biogeosciences, Vol. 11 (23), 2014.

Figure 5 shows that a carbonaceous material, which finds use in the applications described herein, has a significantly higher surface area of approximately 238m ² /g (see far right value in Figure 5). In fact, preferably, carbonaceous materials useful in accordance with the present disclosure have surface areas of about 200 m ² /g to about 400 m ² /g, for instance about 230 m ² /g to about 370 m ² /g. As per Figure 5, the surface area of wood-based material has been determined at about 238 m ² /g, whilst the surface area of switchgrass-based material made by the above-described process has been determined at about 366 m ² /g. Figure 5 only compares wood-based materials. Density

Solid density (ie. skeletal or true density) and bulk (ie. apparent) density are generally used to describe carbonaceous materials, including biochar. The two densities are usually inversely related. In other words, an increase in solid density is often correlated with a decrease in bulk density. This inverse relationship has been demonstrated by Pastor-Villegas et al ("Study of Commercial Wood Charcoals for the Preparation of Carbon Adsorbents", Journal of Analytical and Applied Pyrolysis, vol. 76, pp. 103-108, 2006) for eucalyptus-derived biochar. Solid density has also been reported to increase with an increase in HTT. In particular, it has been put forward that, when HTT is high, the loss of volatiles from the structurally dis-ordered portion of the feedstock and the increase in the graphite-like crystalline structure leads to an increase in solid density due to structural packing in the graphite phases. See Emmerich et al, "Babassu Charcoal: A Sulfurless Renewable Thermo-Reducing Feedstock for Steelmaking", Biomass and Bioenergy, vol. 10, pp. 41-44, 1997.

As a comparison, the typical solid density of charcoals is around 2 Mg/m ³ (Mg = megagram, ie. l,000,000g; Emmett, "Adsorption and Pore-Size Measurement on Charcoal and Whetlerites", Chemical Reviews, vol. 43, pp. 69-148, 1948); while the solid density of graphite has been reported as approximately 2.25 Mg/m ³ (Lehmann J & Joseph S, 2015). The solid density of biochar has been measured at about 1.5 to about 2 Mg/m ³ due to its more amorphous structure (see Jankowska et al, "Active Carbon", Ellis Horwood, New York, 1991; Oberlin, "Pyrocarbon - Review", Carbon, vol. 40, pp. 7-24, 2002; Brewer et al, "Characterization of Biochar from Fast Pyrolysis and Gasification System", Environment Progress and Sustainable Energy, vol. 28, pp. 386-396, 2009).

The solid density of carbonaceous materials is therefore typically dependent upon both the raw material(s) used to form it, and the pyrolysis process employed. Typically, it increases with increasing HTT. With specific regard to bulk density, values reported for carbonaceous materials identified as "biochar" typically range from 0.09 Mg/m ³ to 0.50 Mg/m ³ (Karaosmanoglu et al, "Biochar from the Strawstalk of Rapeseed Plant", Energy and Fuels, vol. 14, pp. 336-339, 2000 [value calculated from the mass of the biochar at 15 °C, which covers a vacancy of 10 cm ³ ]; Ozgimen and Karaosmanoglu, "Production and Characterization of Bio-oil and Biochar from Rapeseed Cake", Renewable energy, vol. 29, pp. 779-787, 2004 [value also calculated from the mass of the biochar at 15 °C, which covers a vacancy of 10 cm ³ ]; Pastor-Villegas et al, "Study of Commercial Wood Charcoals for the Preparation of Carbon Adsorbents", Journal of Analytical and Applied Pyrolysis, vol. 76, pp. 103-108, 2006; Bird et al, "X-ray Microtomographic Imaging of Charcoal", Journal of Archaeological Sciences, vol 35, pp. 2698-2706, 2008; Spokas et al, "Impacts of Woodchip Biochar Addition on Greenhouse Gas Production and Sorption/Degradation of Two Herbicides in a M innesota Soil", Chemosphere, vol. 77,pp. 574- 581, 2009). However, a range from 0.48 Mg/m ³ to 0.73 Mg/m ³ has also been reported (Yargicoglu et al, "Characterization and Surface Analysis of Commercially Available Biochars for Geo-environmental Applications", I FCEE 2015, pp. 2637-2646; published by American Society of Civil Engineers; ISBN (PDF): 978-0-7844-7908-7; method of determination used : ASTM D7263-09). The bulk density of a carbonaceous material useful in accordance with the present disclosure has been determined to be in the range of from about 0.09 to about 0.11 Mg/m ³ , using a method in accordance with ASTM D1762-84 (105C). In comparison with biochar materials reported in the art, therefore, this bulk density range suggests that such carbonaceous materials are comparatively light. Preferred bulk density values for such, useful carbonaceous materials include about 0.09 to about 0.30 Mg/m ³ , more preferably about 0.09 to about 0.11 Mg/m ³ .

This conclusion that such materials are comparatively light is also supported by a comparison of volatile matter content determined in accordance with ASTM D1762-84. Figure 6 illustrates a comparison of volatile matter content determined for carbonaceous material useful in accordance with the present disclosure, which was produced via pyrolysis of hardwood from oak trees at about 1100 °C, and known, wood-based biochar materials, produce using conventional pyrolytic methods for biochar production at 300-700 °C. The volatile matter data in Figure 6 for the comparative materials were obtained from " Characterization and Surface Analysis of Commercially Available Biochars for Geo-environmental Applications", I FCEE 2015, San Antonio, TX, March 17-21, 2015; and "Physical and Chemical Characterization of Biochars derived from Different Agricultural Residues", Biogeosciences, Vol. 11 (23), 2014.

Figure 6 (far right value) shows a volatile matter content of about 7 dry weight % for a carbonaceous material useful in the applications described herein. Without wishing to be bound by theory, the comparably low volatile matter content determined for such carbonaceous material potentially supports the presence of a comparatively high graphitelike crystalline structure, as well as comparatively high solid density and low bulk density. At higher temperature, volatile matter content will start to decrease with the increase in carbon content, as there will be more structural packing in the graphite phase of the material. This will also lead to an increase in solid density and a decrease in bulk density. Typically, useful carbonaceous materials will have a volatile matter content of less than about 20 dry weight %, for instance about 1 to about 15 dry weight %, and preferably about 3 to about 12 dry weight %, for instance about 4 to about 10 dry weight %. Hydrogen/Organic Carbon (H/C _org ) Molar Ratio

H/Corg molar ratio is a commonly used measure of the degree of unsaturation (ie. the presence of C=C double bonds) in organic polymers. The deficiency of hydrogen is used to facilitate the calculation of double bond equivalents, a quantity which is particularly well-suited to the classification of aromatic materials (Lehmann J & Joseph S, 2015). In organic chemistry, delocalised electrons are found in conjugated systems and aromatic compounds. The delocalised electrons are free to move throughout the structure, and give rise to properties such as conductivity. In general, molar H/C _org ratios in carbonaceous materials such as biochar, have been reported to decrease with increasing HTT, typically from about 1.5 to a level below about 0.5 (K. Jindo et al, "Physical and Chemical Characterisation of Biochars derived from Different Agricultural Residues", Biogeosciences, vol. 11, pp. 6613-6621, 2014).

Examples are provided in Table 3, which shows H/C _or g ratios in different wood-based biochar materials. The values in Table 3 are taken from Lehmann J & Joseph S, 2015.

Table 3

In addition, Figure 7 shows a comparison of the H/C _org molar ratio of a carbonaceous material useful in accordance with the present disclosure, provided via pyrolysis at 1100°C of hardwood derived from oak trees, with those for other wood-based biochar produced via pyrolysis at 300-700 °C. The H/C _org molar ratio data in Figure 7 for the comparative materials were obtained from " Characterization and Surface Analysis of Commercially Available Biochars for Geo-environmental Applications", I FCEE 2015, San Antonio, TX, March 17-21, 2015; and "Physical and Chemical Characterization of Biochars derived from Different Agricultural Residues", Biogeosciences, Vol. 11 (23), 2014. The material useful in the applications described in the present disclosure reports a molar H/Corg ratio of 0.17, determined via a hydrogen dry combustion method. In particular, the hydrogen and carbon amounts were determined in accordance with ASTM D4373, and the molar ratio then calculated. The H/C _org ratios reported for the literature biochar materials were determined using elemental analysis. The comparatively low H/C _org ratio of the useful material suggests comparably high aromatic structure and, thus, indicates, a potential for high conductivity performance. Useful carbonaceous materials typically have an H/C _org molar ratio of not more than about 0.35, preferably not more than about 0.25 and more preferably not more than about 0.17.

Electrical Conductivity

The electrical conductivity of biochar conventionally used for soil adjustment is typically linked to the salinity of the soil. It has been reported that, in general, electrical conductivity values tend to increase with pyrolysis temperature (Singh et al, "Characterization and Evaluation of Biochars for their Application as a Soil Amendment", Australian Journal of Soil Research, vol. 48, pp. 516-525, 2010), and it is usually affected by the concentration of metal ions in biochar, such as potassium or sodium (Cantrell et al, "Impact of Pyrolysis Temperature and Manure Source on Physicochemical Characteristics of Biochar", Bioresource Technology, vol. 107, pp. 419-428, 2012). A number of methods for the measurement of electrical conductivity of carbonaceous materials have been proposed. For instance, the International Biochar Directive's (IBI) electrical conductivity testing method suggests equilibration of a 1:20 (weight:volume) solution of biochar to deionized water for 1.5 hours, followed by measurement of the concentration of water-soluble electrolyte. The European Biochar Certificate (EBC) also reported a similar approach. However, these methods are not considered to be as readily comparable to conventional methods used to measure the electrical conductivity of battery anodes, which application is of particular interest herein. Thus, tests using methods suitable for battery application, such as calculation of electrical impedance, have been investigated as more well-suited for this purpose. Nevertheless, a helpful comparison of the electrical conductivity of a carbonaceous material suitable for use in the applications described herein, and that of standard wood- based biochar materials is presented in Table 4 below. The electrical conductivity of the useful material was determined using electrochemical analysis procedures as outlined in section 04.10 of the US Composting Council and US Department of Agriculture (2001), following dilution and sample equilibration methods from Rajkovich et al. (2011), Publisher: Biology and Fertility of Soils, DOI 10.1007/s00374-011-0624-7; or using a four point probe method (Schuetze et a I, "A Laboratory on the Four-Point Probe Technique", American Journal of Physics, 2004, vol. 72, pp.149). The conductivity of the standard wood-based biochars was typically determined in accordance with ASTM D4972-01, the details of which are provided in Table 4.

As before, the carbonaceous material useful in the applications described herein was produced via heating hardwood derived from oak trees under non-oxidative conditions at 1100°C, while the other products are reported as being produced via pyrolysis at 300-700 °C. The electrical conductivity data presented in Table 4 for the comparative materials is taken from "Characterization of Slow Pyrolysis Biochars: Effects of Feedstocks and Pyrolysis Temperature on Biochar Properties", Journal of Environmental Quality, Vol. 41 (4), 07/2012; "Characterization and Evaluation of Biochars for their Application as a Soil Amendment", Australian Journal of Soil Research, Vol. 48 (6-7), 09/2010; and "Corn Growth and Nitrogen Nutrition after Additions of Biochars with Varying Properties to a Temperate Soil", Biology and Fertility of Soils, Vol. 48(3), 04/2012.

E.Saligna 0.21 (S/m) ( - 2.1 Measure in a 1:5 water

- Wood mS/cm) solution after 24h shaking

Orion model 115 A plus

7.2 mS/m (~0.072 conductivity meter (thermo

Oak - mS/cm) fisher scientific, Waltham,

MA)

Orion model 115 A plus

9.6 mS/m (~0.096 conductivity meter (thermo

Pine - mS/cm) fisher scientific, Waltham,

MA)

Useful

1.85 S/m 4.10USCC/Rajkovich carbonaceous - (18.5 mS/cm) dilution

material

Useful

19 S/cm

carbonaceous - Four point probe*

(~ 19,000 mS/cm)

material

Table 4

*Voltage Data collated from the four point probe measurements taken were 0.04069 mV,

0.06067 mV and 0.08160 mV for current of 1.0 mA, 1.5 mA and 2.0 mV respectively for a sample of thickness 2.84 mm. The following calculation was used to determine conductivity: p = ν/ΐ χ π / In 2 x d = 0.04091x r / In 2 x 0.284 = 0.05264 l.cm σ = ί/ρ ~ 19 S/cm where p, V, I, d and σ is resistivity (O.cm), voltage (volt), current (A), thickness (cm) and conductivity (S/cm), respectively.

The electrical conductivity of carbonaceous materials useful in the applications described herein typically lies in the range of about 10 to about 40 mS/cm, preferably about 18 to about 35 mS/cm as determined using the 4.10USCC/Rajkovich dilution method; and about 18,500 mS/cm or more, preferably about 19,000 mS/cm or more, as determined using the four point probe method.

Carbon Content An important defining feature of carbonaceous materials such as biochar is the level of organic carbon atoms, in particular their fused aromatic ring structure content. As per Keiluweit et al (2010), at temperatures of at least about 400 °C, the biochar structure is reported to be dominated by aromatic carbon. The more the biomass is heated, the more such fused carbon rings are created. Non-aromatic carbon also declines sharply with increasing temperature. Thus, according to this general trend, typically less than about 10 % of biochar carbon is non- aromatic at temperatures of at least about 400 °C.

As reported in Lehmann J and Joseph S (2015), there are a number of terms typically applied to the different types of carbon atoms found in pyrogenic carbonaceous materials (PCMs). In particular, "Black Carbon" refers to the carbon atoms per se, and not to the PCM, which can also contain hydrogen, oxygen, nitrogen and ash minerals for instance. "Pyrogenic carbon" (PyC) is synonymous with black carbon. It refers to the non-inorganic carbon atoms, which have undergone pyrogenic or thermal transformation and, by this definition only include carbon present in fused rings, including carbon on the surface of fused aromatic carbon, which may also bind to other carbon atoms, such as C-O/N substituents, non-protonated carbon and protonated carbon. Finally, "Total organic carbon" (TOC) refers to the entire organic carbon component of any such material, including all thermally altered organic carbon as well as remaining, untransformed organic carbon. "Total inorganic carbon" (TIC) mainly includes carbonate and possible other compounds such as oxalates.

Importantly, the aromatic structure in such carbonaceous materials gives rise to high chemical stability. Typically, biochar is rich in carbon, and the content increases with heating temperature. It has been reported that this is due to carbonisation at relatively higher temperatures (eg. about 600 or 700 °C), which results in a high degree of carbon provided in in aromatic form, in particular in aromatic ring structures (see, for example, Novak JM et al, "Characterization of Designer Biochar produced at Different Temperatures and Their Effects on an loamy Sand", Annals of Environmental Science, vol. 3, pp. 195-206, 2009). Carbonisation is marked by the removal of most non-carbon atoms and the consequent relative increase in carbon content, which can be up to about 90 % in biochar from wood-based raw materials, for instance (see, for example, Antal and Gronii, "The Art, Science and Technology of Charcoal Production", Industrial Engineering and Chemistry Research, vol. 42, pp. 1619-1640, 2003). Tables 5 and 6 below provide a useful comparison of different type of carbons. Table 5 reports the so-called "proximate analysis" of two feedstocks, which analysis provides a breakdown of volatile matter, fixed carbon and ash. In particular and when starting with cellulose, lignin or hemicellulose, for example, heating under non-oxidative conditions drives off the volatile matter (ie. organic carbon bound in volatile C-H-0 structures). After the volatile matter has been thermally changed into a gas phase, what is left is the residual "fixed carbon". Volatile matter decreases with increasing temperature (see, for example, Figure 6), while fixed carbon shows a reverse trend. "Fixed carbon" is a very stable form of organic carbon, which is resistant to decomposition and, if the biochar material is used as a soil enhancement agent, remains in the soil. The content of fixed carbon can be calculated by subtracting the mass proportions of volatile matter and ash from 100, as reported in Table 5.

The so-called "ultimate" analysis (reported in Table 6) directly provides a comparison of the main elements present in the carbonaceous materials, eg. biomass-derived materials, in particular carbon, hydrogen and oxygen. The carbon content of biomass, for example, is typically directly related to the content of hemicellulose, cellulose and lignin in the biomass.

1. "Corn Growth and Nitrogen Nutrition after Additions of Biochars with Varying Properties to a Temperate Soil", Biology and Fertility of Soils, Vol. 48 (3), 04/2012.

Table 5: Proximate Analysis Elemental analyser (CHNS-0 EA

Poplar Wood ⁴ 71 - 1108)

Elemental analyser (CHNS-0 EA

Spruce Wood ⁴ 71 - 1108)

Dry Combustion - Vario Max CNS

E.Saligna Wood ³ 56 - Analyser

Wood Chips Elemental Analyser (Thermo

78 - Apple Tree ¹ Finnigan EA-1112)

Elemental Analyser (Thermo

Oak Tree ¹ 78 - Finnigan EA-1112)

Pine Wood ² 53 - Perkin-Elmer Elemental Analyser

Useful

carbonaceous 84 Dry Combustion- Elemental Analyser material

1. "Physical and Chemical Characterization of Biochars derived from Different Ag Residues", Biogeosciences, Vol. 11 (23), 12/2014.

2. "Characterization and Surface Analysis of Commercially Avialable Biochars for Geoenvironmental Applications", I FCEE 2015, San Antonio, TX, March 17-21, 2015

3. "Characterization and Evaluation of Biochars for their Application as a Soil Amendment", Australian Journal of Soil Research, Vol. 48 (6-7), 09/2010

4. "Characterization of Slow Pyrolysis Biochars: Effects of Feedstocks and Pyrolysis Temperature on Biochar Properties", Journal of Environmental Quality, Vol. 41 (4), 07/2012.

Table 6 - Ultimate Analysis

In the context of the present disclosure, therefore, useful carbonaceous materials typically comprise at least about 65 % fixed carbon, more preferably at least about 70 % to about 95 % fixed carbon, and more preferably about 75 % to about 90 % fixed carbon.

Summary of Properties of Carbonaceous Materials useful in the Present Invention

In summary, therefore, carbonaceous materials useful in the applications described herein display a number of key properties, which set them apart from other carbonaceous materials reported in the literature and which have been found to render them particularly suitable for use in a range of new applications, which are described in the following paragraphs. These properties are facilitated by the way in which the carbonaceous materials are produced, specifically via heating under non-oxidative conditions, eg. in the absence of oxygen, of at least one compound comprising carbon, oxygen and hydrogen at a temperature of at least about 700 °C, and thus at higher HTT. The resulting carbonaceous materials possess higher carbon content, lower H/C _or g molar ratio, greater proportions of aromatic, graphite-like structure, and greater proportions of delocalised electrons within their molecular structures which, in turn, facilitates higher electric conductivity. Useful carbonaceous materials are porous and possess higher surface area than materials produced at lower temperatures. In addition, their bulk density indicates that such materials are comparatively lighter than those made at lower temperatures.

Uses of Carbonaceous Materials

The present inventors have found that the above-described properties of carbonaceous materials made via heating of at least one compound comprising carbon, oxygen and hydrogen at at least about 700 °C render them particularly suitable for use in a range of applications, including both applications involving energy transfer and storage, and applications involving the absorption of media, in particular gases.

Energy Storage, Generation and Conversion Applications

An area of on-going interest today in the field of energy storage and generation is the provision of environmentally more friendly power sources. To date, lithium ion batteries have dominated the rechargeable battery industry as they possess high energy storage capacities. A lithium ion battery consists of an anode, which typically comprises carbon, and a cathode typically comprising a lithium/transition metal system. Known carbon anode materials include titanium-based materials, carbon-based graphites, hard-carbon, graphene oxide and their composites. The performance of a lithium ion battery strongly depends upon the storage capacity and electrical conductivity of the materials used in its production.

So far, graphite has been identified as a possible candidate for such use, due to its high specific capacity (it has a theoretical limit of about 372 mAh/g). However, it is a relatively expensive material, in comparison with the useful carbonaceous materials described herein. I n more detail, in comparison with such carbonaceous materials, the production of graphite is quite complex and is considered to be non-environmentally friendly. Generally, there are two kinds of graphite: natural and synthetic graphite. Natural graphite can be sourced by mining. However, its recovery requires a diverse range of energy intensive processes including excavation, mine operation and separation processes, for example. Synthetic graphite is derived from high temperature processes involving fossil fuel material such as calcined petroleum cake or coal tar pitch. Synthetic graphite has superior consistency and purity and it is, therefore, preferred by battery manufacturers. However, natural graphite is much cheaper than synthetic graphite. Because of this, China, which is the world's largest graphite producer, has sacrificed significant geographical areas, with a corresponding high environmental cost, in order to mine and export the commodity. In contrast, the production of carbonaceous materials such as biochar is thus more simple, more environmentally friendly and more cost efficient. The recycling of biomass waste to produce energy products and carbonaceous materials such as biochar can be seen as a sustainable cycle. Thus, the use of carbonaceous materials made in accordance with the above-described process will have a positive environmental impact upon industries, such as the energy storage and energy generation industries.

The criteria in choosing material for battery usage are, therefore, high capacity and good conductivity, low mass, low cost and good chemical and physical stability. Carbonaceous materials described herein have been found to meet these needs.

Furthermore, the ever-increasing energy demand worldwide has motivated the search for clean energy sources. Hydrogen has high energy density and is considered as a most promising energy carrier for providing clean and sustainable energy systems to prevent climate changes related to the use of fossil fuels. Electrolysis (a form of energy generation) is a good option for producing hydrogen very quickly and conveniently, in particular proton exchange membrane electrolysis. There are few ways to convert chemical energy of hydrogen into electrical energy. Among others, hydrogen, used in fuel cell technology (a form of energy conversion), is considered as one of the most promising alternatives, due to its fast start-up, relatively low operational temperature, high efficiency and power density. Carbon plays very important role in electrolysis and fuel cell applications, helping to improve cell performance by minimizing ohmic resistances, improving electrochemical surface area (eg. when used as supported carbon), improving structural integrity and improving water management.

At the present time, Vulcan XC-72 is the most utilized conducting carbon for electrolyser and fuel cell applications and is widely commercially available from numerous suppliers. However, the replacement of currently-used conducting carbons with carbonaceous materials described herein, for instance biomass-derived carbon, as starting materials for the production of carbon electrodes is highly advantageous due to their abundance, low cost, simple and green manufacturing methodologies, and their desirable physical properties such as high porosity.

Electrochemical Testing

Electrochemical testing to determine specific capacity was performed in the voltage ranges of 0-2 V and 2-4.5 V upon a carbonaceous material useful in the applications described herein, which was made via pyrolysis of hardwood from oak trees at 1100 °C, and upon activated carbon sold under the tradename DARCO ^® by the Sigma-Aldrich ^® Company (product number: 242276; CAS number: 7440-44-0). The testing was performed in coin cells using 1M LiPF6 in ethylene carbonate: diethyl carbonate (EC:DEC) as electrolyte and using lithium metal as the counter-electrode. The coin cells were cycled using a battery cycler commercially available from Neware (Shenzhen, China).

Coin cells are widely used in research laboratories to test the capacities of new materials. A coin cell consists of a working electrode (ie. the material under test), a lithium counter- electrode and an electrolyte (as mentioned above). The coin cell is connected to a battery tester and a voltage window is defined for the test. Galvanostatic charge-discharge is recorded and specific capacity is determined.

Galvanostatic cycling thus involves the application of a current to the working electrode until the potential hits a specified limit. The capacity is calculated from the current applied (in milliamps) and the time (in hours), for which it was applied before the voltage hit a specific limit (eg. 2 V or 4.5 V in this case). Specific capacity is the capacity value normalised to the weight of the active mass on the electrode that was tested. Subsequently, capacitance can be calculated using the following equation to derive specific capacitance from the specific capacity:

Specific Capacitance (C, Farad/gram) = Specific Capacity (mAh/g) x 3600/ Voltage (mV) (See Nagasubramanian et al., Nano Energy, Vol. 12, pp. 69-75, 2015).

The results of the electrochemical testing are presented in Figure 8, which shows specific discharge capacity vs. cycle numbers. In Figure 8, the useful carbonaceous material is identified as "BMC" and, for the 0-2.0 V testing, is plotted at a specific capacity of approximately 120 mAh/g; while, for the 2-4.5 V testing, it is shown plotted at a specific capacity of approximately 0 mAh/g. The commercially available carbon product tested is identified in Figure 8 as "Sigma". For the 0-2.0 V testing, this product is plotted at a specific capacity of approximately 120 mAh/g; while, for the 2-4.5 V testing, it is shown plotted at a specific capacity of approximately 40 mAh/g. Thus, Figure 8 shows that, at the voltage range of 0-2.0 V, both capacity curves are overlapped and achieve comparable results whereas, at the higher voltage range of 2-4.5 V, the carbonaceous material did not perform as well as the commercially available carbon product.

In the context of the disclosure, useful carbonaceous materials typically have a specific capacity (measured as detailed above) of at least about 120 mAh/g, more preferably at least about 150 mAh/g to at least about 400 mAh/g, for example about 365 mAh/g to about 380 mAh/g, for instance about 372 mAh. Materials useful in the present invention can also have specific capacity values in excess of about 372 mAh/g, for instance in excess of 400 mAh/g, and significantly higher than this value. The results of further electrochemical testing are shown in Figures 9 and 10. In particular, two samples of useful carbonaceous material were tested for possible use in supercapacitors using aqueous electrolyte (potassium hydroxide; KOH). The two sample carbonaceous materials are identified in Figures 9 and 10 as "Process 1" and "Process 2" as they were made by two different ratios of carbonaceous material and activation agent (KOH). In more detail, the "Process 1" carbonaceous material derived from wood was heating under non-oxidative conditions at 900 °C with a 1:1 ratio of carbonaceous material and activation agent. The "Process 2" material was made heating under non-oxidative conditions at 900 °C with a 1:2 ratio of the carbonaceous material and activation agent. The electrochemical performance of these sample materials was compared with that of an untreated original carbonaceous material, which is identified as "Org Carbon" in Figures 9 and 10. Figure 9 shows the specific capacitance at different scan rates of a cyclic voltammetry (CV) study, at the voltage range of 0 - 0.2V. From the results, it is clearly seen that there is an increase in specific capacitance with the different carbon activation processes. In particular, the activated carbonaceous materials show superior performance in comparison with that of the original carbonaceous material (without activation). The same trend was also observed for Galvanic Cycle Tests (ie. Charge - Discharge Tests) and impedance analysis. The results of impedance analysis are presented in Table 7 below, in which R _s and R _P represent resistance series and resistance parallel respectively.

Table 7: Impedance Analysis In addition to good capacity, carbonaceous materials useful in the applications described herein are also cheap to manufacture, light-weight and stable. They also possess carbon content and surface area values, which are comparable to those of carbon-based materials currently used in battery applications. These properties render them extremely beneficial for use as electrodes in energy storage, energy conversion and energy generation systems. They may be used in the production of both anodes and cathodes, and find particular use in anodes.

They are particularly effective when used in the production of energy storage systems, such as batteries, capacitors and supercapacitors. In particular, they are useful in rechargeable batteries, preferably lithium ion rechargeable batteries or aluminium ion rechargeable batteries.

With particular regard to the effective use of such materials in the provision of supercapacitors, it is noted that electrode materials currently used in supercapacitors are typically carbon-based materials, transition metals or conducting polymers. As already described for battery usage, materials useful in supercapacitor manufacture require good electrical conductivity and good capacitance, as well as high surface area, low mass and good stability. It is also of course advantageous if they are low in cost to manufacture. The inventors have found that carbonaceous materials made via heating of biomass, for example, under non-oxidative conditions at temperatures of at least about 700 °C possess these characteristics and are, thus, potentially useful in the production of supercapacitors.

The carbonaceous materials described herein are also very effectively used in electrodes for energy conversion or generation devices. For example, they find use in electrolysers, including polymer electrolyte membrane water electrolysers and alcohol electrolysers; and also in fuel cells, in particular low temperature fuel cells, phosphoric acid fuel cells, polymer electrolyte membrane fuel cells and direct methanol fuel cells. These uses provide an effective way of employing such carbonaceous materials, the production of which provides an environmentally useful way of dealing with vast quantities of waste, carbon-containing materials, in particular biomass.

Use of Carbonaceous Materials as Absorbents

As already described, carbonaceous materials made via heating of carbon, oxygen and hydrogen-containing compounds under non-oxidative conditions at temperatures of at least about 700 °C possess higher surface area than materials produced using lower temperature pyrolysis. Surface area is understood to be a consequence of porosity and pore size distribution. In addition, such materials possess good chemical and physical stability. These are key requirements for materials to be used in a range of absorbent applications, for instance those applications where activated carbon is typically used, for example in waste water treatment to remove impurities via absorption. In addition, absorbent applications such as gas storage, in particular of hydrogen gas and natural gas, are of particular interest in the context of the present disclosure.

Natural gas storage in carbonaceous materials is potentially advantageous, as the gas can be stored at low pressure, making such storage safer than traditional storage in big compression tanks, where the danger of explosion is very high. In recent years, hydrogen gas has developed an increasingly important role as a transportation fuel due to rapid advances in fuel cell technology. However, one of the major challenges associated with the use hydrogen gas as transportation fuel is its storage. One proposed solution has been the storage of hydrogen in porous materials. Materials investigated for this include templated carbons, carbide-derived carbons and activated carbon.

Activated carbon remains the most studied class of carbon materials for hydrogen storage. The preparation process of activated carbon typically includes either a i) two step physical activation or ii) one step chemical activation. Physical activation consists of producing a carbon material from organic matter (for instance using pyrolysis or gasification), followed by a further gasification step (with oxygen, air, steam or carbon dioxide) to increase the surface area and pore volume of the carbon material. Chemical activation involves mixing a carbon- containing precursor with a chemical agent (eg. potassium hydroxide, sodium hydroxide, zinc chloride) before subjecting the precursor so-treated to a pyrolysis process. Chemical activation typically results in better physical properties of the resulting activated carbon product and is, thus, the preferred method for production of activated carbon for use in hydrogen storage. These processes for the production of activated carbon are, however, very time-consuming and expensive.

Therefore, the use of carbonaceous materials, which are the direct products of a more simplified process comprising heating of at least one compound comprising carbon, oxygen and hydrogen under non-oxidative conditions, eg. in the absence of oxygen, at a temperature of at least about 700 °C, presents an advantageous, alternative method for the provision of carbonaceous materials with properties very well-suited to the absorption of a range of materials. I n particular, they are well-suited for use in gas absorption, more preferably hydrogen gas absorption or natural gas absorption.

In this context, the "direct product" of the above-described heating step is understood to mean the product of the heating step without further processing, or such a product which may have been subjected to further processing steps which may alter its physical structure, for example in terms of the form of the product, eg. blocks, spheres etc., but which further processing does not alter the chemical nature of the product. Gas storage devices comprising carbonaceous materials described herein as an absorbent may be provided by replacing standard absorbent materials in known gas storage devices with the carbonaceous material. Such a storage device can then be incorporated into a system additionally comprising a device which will ultimately make use of the stored gas, such as a fuel cell. In this context, fuel cells can make use of each of hydrogen and natural gas stored in gas storage devices in accordance with the present invention. In particular, such stored natural gas is fed into a high temperature fuel cell.

Carbonaceous materials described herein are also well-suited for use in applications where activated carbon is traditionally used including, for example, in the absorption of a variety of species from liquids, such as the removal of impurities from liquids such as water, including waste water for example. Thus, such materials can be effectively incorporated into water treatment devices, in particular waste water treatment devices, for this purpose.