Microwave torrefaction of biomass

Abstract

There is described a processor for use in the microwave torrefaction of biomass material which comprises, a micronized biomass char material and a method of producing a biomass char material, and a method of producing L-glucosan.

Claims

1. A processor for use in the microwave torrefaction of biomass material which comprises: (i) a material densifier to compress the biomass and preheat the biomass material; (ii) a microwave unit adapted to conduct microwave-assisted torrefaction of biomass material, the unit comprising a feed pipe for transfer of the biomass material comprising gas and/or liquid outlets to enable rapid removal of gas and/or liquid formed during torrefaction, wherein the material densifier is integral with the microwave unit for preheating the biomass material entering the microwave unit.

2. A processor according to claim 1 wherein the material densifier is arranged and configured to produce continuous rods of material.

3. A processor according to claim 1 wherein the processor further comprises a carrier tube arranged and configured for feeding densified biomass material directly into and through the microwave chamber.

4. A processor according to claim 1 wherein the microwave unit further comprises a chamber which comprises: a feed pipe; wherein the feed pipe is arranged and configured such that there is minimum void between the biomass material and an inner wall of the feed pipe and wherein the feed pipe is fitted with one or more gas and/or liquid outlets.

5. The processor of claim 1, wherein the preheating of the biomass material by the densifier is a result of mechanical friction and compression.

6. A processor for use in the microwave torrefaction of biomass material which comprises: a microwave unit adapted to conduct microwave-assisted torrefaction of biomass material, the unit comprising: a feed pipe for transfer of the biomass material comprising gas and/or liquid outlets to enable rapid removal of gas and/or liquid formed during torrefaction; and a material densifier integral with the microwave unit to compress the biomass and preheat the biomass material entering the microwave unit.

Description

(1) The invention will now be described by way of example only and with reference to the accompanying figures, in which;

(2) FIG. 1 is a schematic representation of a microwave processor;

(3) FIG. 2 is a graph illustrating the separation of aqueous and organic fraction based on microwave time;

(4) FIG. 3 is a schematic representation of apparatus set-up for simultaneous microwave-IR experiment;

(5) FIG. 4A) is a Gram-Schmidt trace for isotherm pyrolysis of pelletised biomass and FIG. 4B) is an IR spectrum of the fractions;

(6) FIG. 5 is a graph illustrating the relationship of the specific microwave energy (amount of microwave energy per unit mass which the biomass absorbs) with the degree of densification of wheat straw;

(7) FIG. 6 is a schematic representation of the apparatus set-up for the microwave extraction of volatiles from rape meal;

(8) FIG. 7 is a graph of the microwave profile for the extraction of volatiles from Rape Meal;

(9) FIG. 8A is a Differential Scanning calorimetry analysis of the rape meal oil extract and FIG. 8B a Thermogravimetric analysis of the rape meal extract;

(10) FIG. 9 is a FTIR spectrum of the liquid organic compounds extracted from rape meal;

(11) FIG. 10 is a schematic representation of the apparatus set-up for microwave co-extraction of volatile organic compounds with water from pine wood;

(12) FIG. 11 is a graph of the microwave profile for the extraction of volatiles from pine wood pellets;

(13) FIG. 12 is a FTIR analysis on the volatile extracts from pine wood obtained at the different irradiation power;

(14) FIG. 13 is a graph of the microwave profile of rape meal extracted with n-pentanol;

(15) FIG. 14 is a FUR spectrum of extracts from rape meal with pentanol and water;

(16) FIG. 15 is a schematic representation of the apparatus set-up for microwave extraction of secondary oil from biomass with capture of highly volatile components;

(17) FIG. 16 is a FTIR spectrum of extracts from cellulose, miscanthus, rape meal and Norway spruce;

(18) FIG. 17 is a graph illustrating the calorific value of cellulose chars produced by conventional pyrolysis and microwave irradiation at different temperatures;

(19) FIG. 18 illustrates the direct microwave effect on cellulose;

(20) FIG. 19 is a FTIR of different types of biomass before and after microwave irradiation;

(21) FIG. 20 is a C.sup.13 NMR of cellulose chars of same elemental composition produced by conventional pyrolysis and microwave irradiation;

(22) FIG. 21 is a graph illustrating the calorific value of hemicellulose chars produced by conventional pyrolysis and microwave irradiation at different temperatures;

(23) FIG. 22 is a graph illustrating the heat of oxidation values for biomass samples before and after MW irradiation;

(24) FIG. 23 is a STA (Simultaneous Thermal Analysis) profile of barley dust mixed with PdO as an oxidant to measure heat of combustion;

(25) FIG. 24 is a STA profile of barley dust after microwave processing;

(26) FIG. 25 is a STA profile of rape meal;

(27) FIG. 26 is a STA profile of rape meal after microwave processing;

(28) FIG. 27 are thermogravimetric IR spectra of volatiles at temperature 330 C. for rape meal before and after microwaving;

(29) FIG. 28 are thermogravimetric IR spectra of volatiles at temperature 390 C. for rape meal before and after microwaving;

(30) FIG. 29 is a graph illustrating the influence of graphite on the product distribution in microwave thermal treatment;

(31) FIG. 30 is a STA profile of pine wood before microwave treatment;

(32) FIG. 31 is a STA profile of pine wood after microwave treatment;

(33) FIG. 32 is a graph illustrating the percentage energy per gram of starting material maintained in the char;

(34) FIG. 33 is a graph illustrating the energy input for microwave torrefaction at 270 C. for different sample masses;

(35) FIG. 34 is a graph illustrating the influence of acid/base additives on the relative change of A) char yield and B) oil yield from wheat straw in microwave torrefaction;

(36) FIG. 35 is a schematic representation of a microwave experiment;

(37) FIG. 36 is a GC-MS trace of wheat straw microwave pyrolysis oil

(38) FIG. 37 is a GC-MS trace of wheat straw microwave pyrolysis oil prepared in the presence of H.sub.2SO.sub.4;

(39) FIG. 38 is a GC-MS trace of wheat straw microwave pyrolysis oil prepared in the presence of HCl;

(40) FIG. 39 is a GC-MS trace of wheat straw microwave pyrolysis oil prepared in the presence of ammonia;

(41) FIG. 40 is a GC-MS trace for the fast pyrolysis of wheat straw at 600 C.;

(42) FIG. 41 is Table 2.1 of results from the analysis of sealed up rape char;

(43) FIG. 42 is Table 2.2 of results from the analysis of sealed up rape charmetal impurities; and

(44) FIG. 43 is Table 2.3 of particles size distribution.

EXAMPLE 1

Example 1.A

(45) Biomass Processor

(46) The schematic layout of the processor is illustrated as an example in FIG. 1. The biomass is fed at point (1) where, as necessary, it can be pulverised and dried. The drying can optionally be conducted with heat generated by the microwave process utilising a heat exchanged at point (7). Pulverisation should be carried out buy equipment suitable for the biomass to be processed. Typically a hammer mill or chopper used in standard biomass densification technologies can be used although other appropriate means can also be employed.

(47) The pulverised biomass is then fed into a densification chamber (2). This can be a standard commercially available pelletiser, or a briquetter but preferably one capable of producing continuous rods which can be fed into outlet (3). Screw type extruders capable of continually feeding material are also appropriate and preferred. If appropriate liquid additives, such as, but not limited to those used in typical densification processes, e.g. glycerol or waste glycerol, or other known additives, such as, ammonia, hydrochloric or sulphuric acid, etc., can be mixed in to help material processing into a dense rod. The density of the extruded material that can typically be achieved by commercial processors, but typically, not essentially, higher densities (in excess of 600 kg/m3 are preferred). The densifier (2) should be equipped with temperature and processing rate control to allow flexibility and control of the system to allow for variability in the feed material. Optionally it can be fitted with an outlet for exhaust gasses generated in the pressing processes. Additionally the densifier (2) should be fitted with a gas inlet near outlet (3) for feeding gases which suppress flame formation and/or assist removal of vapours, gasses and liquids generated in the microwave assisted degradation process. These can include, but are not limited to nitrogen, hydrogen, carbon dioxide, acidic or basic vapours or other additives which can help to catalyse certain processes. The material should be preheated in the process either through mechanical compression, auxiliary heating (which can be utilised from the heat exchanger at point (7)) or both. The preheating temperature should be between 100 and 300 C., preferably 120-250 C., more preferably 160-220 C. and most preferably 180-200 C.

(48) The compressed feed material together with the gas is fed into outlet (3) into a carrier tube (4). If the material is prepared in short pellets rather than a continuous feed a means of propulsion should be integrated into the densifier (2) to ensure feeding and continuous passage of the material through the carrier tube (4) whilst overcoming friction between the carrier tube and the densified material. The carrier tube (4) feeds material directly into and through the microwave chamber and takes the bio-char out at the end of the degradation process.

(49) The carrier tube should be constructed of a strong material, which is transparent to microwaves, heat resistant to at least 300 C. and capable of withstanding mechanical pressure of the fed materials as along with the pressure of the evolved gasses during the process. It should also have low friction to allow smooth transfer of material within close contact to the sides. Construction materials can for example include glass, toughened or Pyrex glass, or other suitable non-metallic material. Choice of a suitable construction material can allow online monitoring such as, but not limited to, NIR probes, laser probes or UV-Vis. measurements, which can aid control of the process.

(50) The tube (4) can be cylindrical with a uniform diameter throughout. The diameter of the tube will be governed by the size of the extruded/pressed material and its density as well as the penetration ability of microwaves which depend on wave parameters and power. Tube diameter should typically be less than 50 cm to ensure sample is irradiated throughout and sizes of about 0.5-10 cm in diameter are most preferable. The carrier tube can also optionally be irregular in shape having a conical shape with a progressively smaller diameter following the degradation reaction to account for the resulting mass loss. The exact specification of the reduction in size will depend on the reaction conditions employed, biomass used and the pre-treatment employed. Similarly the length of the tube will depend on process parameters, including the diameter of feed material, rate of feed, microwave power, number of microwave irradiation points used and others.

(51) The pressed material is fed into the microwave chamber the chamber should be fitted with at least one microwave irradiation source, if more than one irradiation source is used they can optionally be shielded from each other to allow better control of the reaction. A simple low power microwave source is typically required as reactions are very rapid. Typically a 15 mm biomass cylinder can be charred in around 10 seconds at 300 W power input, larger volume of, for example 35 mm can take around 200 seconds, but this relationship is not linear. Higher power microwave generators, or more sequenced generators might be required for high throughput rates. The process conditions can easily be controlled by altering the feed rate from the densifier. The microwave irradiation can be focused around the carrier tube (4) or reflected around the chamber. The microwave source should be located in any geometry which is perpendicular or angled along the carrier tube (4) in some cases use of reflective mirrors might be beneficial to ensure uniform sample irradiation.

(52) Inside the chamber the carry tube should be fitted with exhaust tubes to enable the removal of degradation vapours (5) and liquids (6) placed preferably on top and bottom of the tube respectively. The removal of volatile or liquid products will be promoted by the mixed gas (e.g. nitrogen) and/or can be assisted by vacuum. The exact positioning of the outlet tubes will depend on process parameters, but flexibility is build into the process through control of feed rate, density, microwave power and other aspects to enable optimisation. Typically the outlets will be placed in direct proximity to the area where pyrolysis occurs. The outlets can be angled along the flow of the material in the tube to minimise particulate matter entering the outlet holes. Additionally these can be fitted with traps for any particulate or early condensing matter and/or appropriate filters. The length of the outlet tubes within the microwave chamber (9) should be kept to the minimum to ensure material is removed from the degrading environment as soon as possible to avoid secondary reactions, unless these are particularly required by the application. Once outside the volatile and liquid products can be treated in conventional ways.

(53) Significantly, this design has sufficient flexibility built in to enable fractionation of the degradation products. A number of outlets can be used to facilitate the process spaced according to the progress of reaction(s) along the carrier tube. This can be used in conjunction with sequential microwave sources to allow for better process control. For example at an early stage water vapour can be removed followed by more organic fractions and chars. Fractionation of the degradation products is an important and innovative aspect of this invention. It enables users to take full advantage of the low temperature employed in the process to preserve chemical functionality and offers an opportunity for the users to maximise the value of their chemical products resulting from the degradation.

(54) Furthermore, in addition to the outlets, the feed pipe may contain inlets for injecting additives such as ammonia or other gaseous, liquid and potentially solid additives, as hereinbefore described, at a controlled point in the process to affect particular reactions.

(55) At the end of the pyrolysis the remaining bio-chars are pushed out of the microwave chamber into a cooling area (7). At the end of the microwave process the bio-char can reach temperatures in excess of 300 C., to avoid potential for fires the bio-char must be cooled. At this stage, optionally, a heat exchanger is used where by the heat dissipated from the char can be transferred to drying and/or preheating the feed material in the pulverisation stage or densification. Use of a heat exchanger can significantly improve the energy footprint of the process. Additionally other elements of the process should preferably be insulated to avoid loss of valuable heat energy.

Example 1.B

(56) Influence of Microwave Time on Cellulose Decomposition Products Under Vacuum

(57) Pyrolysis of cellulose under vacuum was carried out. 50 g of cellulose was preheated at 80 C. and placed inside a Milestone microwave. Microwave irradiation with power 1200 W was applied to the sample during 12 minutes. The typical pressure profile for organic volatiles produced from cellulose under microwave conditions is shown in FIG. 2. As it is indicated in FIG. 2 there are minimum two stages of volatile compounds production: 1) broad low temperature peak around 120 C. and 2) rapid process (narrow peak) at temperature around 180 C. These two fractions were separated by time and analysed. It was shown that the first fraction consists essentially of water which contains acetic and formic acids in combination with formaldehyde and acetaldehyde. This demonstrates that under these conditions (initial preheating temperature below optimum of 180 C.) it is possible to collect two liquid fractions. Firstly, an aqueous fraction is collected with a relatively high acid content at temperatures as low as 60-120 C. and in a period of 3-5 minutes. Thereafter, and by maintaining low temperature control, an organic fraction of low water and low acid content is produced at temperatures around 180 C. within 1-2 minutes. The organic fraction has been collected in yields of up to 21% (water content <1%) from the microwave processing of cellulose. So, simple positioning of outlet tubes, e.g. extraction tubes, along the microwave carrier tube enables the separation of aqueous and organic fractions.

Example 1.0

(58) Influence of Microwave Time on Decomposition of Preheated Biomass Pellets Under Nitrogen Flow

(59) Thermal decomposition of canary grass pellets under nitrogen atmosphere was carried out as shown in FIGS. 3 and 4. The apparatus included a microwave and IR gas cell for monitoring off gases.

(60) 5 g of canary grass pellets was preheated at 180 C. and placed inside CEM microwave. Microwave irradiation with power 300 W was applied to the sample during 6 minutes. The typical Gram-Schmidt profile (which was calculated as integral of IR gas spectrum) for organic volatiles is shown in FIG. 4. There are at least three stages during the period of microwave decomposition occurring sequentially in time:

(61) 1) removal of water with and low boiling aldehydes and acids;

(62) 2) removal of CO.sub.2 and CO accompanied by organic compounds; and

(63) 3) removal of compounds containing hydroxyl groups.

Example 1.D

(64) Influence of Biomass Density on Microwave Decomposition of Biomass

(65) Number of biomass samples with different density were decomposed with microwave thermal treatment to chars. Energy absorbed by the samples was calculated. FIG. 5 shows influence of sample density on the energy efficiency of microwave decomposition.

Example 2.1

(66) Microwave Extraction of Primary Oil & Wax from Rape Meal in Water

(67) The use of microwave radiation and water to extract the primary oil and wax extracts from rape meal was carried out using the following procedure.

(68) Rape meal (4 g) and water (8 g) were weighed out into a round bottom flask with a magnetic stirrer. This mixture was then placed in a laboratory microwave in the open vessel settings. The typical parameters used in the microwave are: power 300 W; time: 1 to 15 minutes; stirring: ON; cooling: OFF.

(69) To the round bottom flask containing the sample mixture a two-necked adapter was attached with one inlet allowing a supply of nitrogen to ensure no oxidation of the materials during the run and the second to allow a Dean-Stark apparatus to be attached with a condenser with cooling set to 10 C. to collect the primary extract. A second condenser with cooling to 60 C. (acetone/liquid nitrogen mixture) was attached, with a two-necked round bottom flask beneath. The complete apparatus set-up is shown in FIG. 6. Primary extracts will mainly originate from extraction in the first H.sub.2O region as shown in FIG. 7 of the microwave profile, a second separate fraction of the primary oil originates from the second H.sub.2O region between 200 and 400 sec and temperature around 120 C.

Example 2.2

(70) Fractionation

(71) Microwave Extraction of Secondary Extracts from the Aqueous Region of Rape Meal

(72) Extraction of the secondary extracts for rape meal, which could contain some primary extracts, microwave modified primary extracts and microwave modified solid material that has become extractable from rape meal was conducted using the methodology described in example 1. Secondary extracts will mainly originate from the decomposition regions as shown in FIG. 7 of the microwave profile, temperature above 130 C.

(73) The sample collected in the first condenser was a mixture of water and a yellow oily liquid. The organic layer was separated from water and tested on an STA and FTIR. The main fraction of organic liquid (FIG. 8A) has a melting point ca. 13 C. and a boiling point was ca. 245 C. (FIG. 8B). In FTIR spectra there were peaks which correspond to fatty acids or their derivatives (FIG. 9).

(74) In the second condenser sulphur containing gases and residues were found.

Example 2.3

(75) Influence of Microwave Irradiation Power on Extraction of Secondary Oil from Pine Wood Pellets

(76) Extraction of the primary oil and wax extracts from pine wood was carried out as detailed in example 1. The scheme of complete apparatus set-up is shown in FIG. 10. The typical temperature profile for pine wood pellets under microwave conditions is shown in FIG. 11. FTIR analysis can be seen in FIG. 12 of the extracts.

Example 2.4

(77) Microwave Extraction of Primary Oil & Wax from Rape Meal in 1-Pentanol

(78) Extraction of the primary oil and wax extracts from rape meal with 1-pentanol instead of water was carried out as detailed in example 1, with the microwave profile shown in FIG. 13. Comparison of FTIR spectrum of oil samples obtained with 1-pentanol and water, as can be seen in FIG. 14, show difference in nature of the oils obtained.

Example 2.5

(79) Microwave Extraction of Secondary Oil from Rape Meal with Capture of Highly Volatile Components

(80) The use of microwave radiation to extract the secondary oil from rape meal was carried out using the following procedure.

(81) Rape meal (4 g) was weighed out into a round bottom flask with an overhead stirrer. This mixture was then placed in a laboratory microwave in the open vessel settings. The typical parameters used in the microwave are: power 300 W; time: 1 to 15 minutes; stirring: ON; cooling: OFF.

(82) To the round bottom flask containing the sample mixture a two-necked adapter was attached with one inlet allowing a supply of nitrogen to ensure no oxidation of the materials during the run and the second to allow a water cooled condenser to be attached with a round bottom flask beneath to collect the extracts. A dichloromethane trap was connected in series with the round bottom flask to capture volatile components, as shown in FIG. 15. FTIR analysis of different oil extracts can be seen in FIG. 16.

Example 2.6

(83) Microwave Extraction of Secondary Oil from Miscanthus with Capture of Highly Volatile Components

(84) Extraction of the secondary oil from Miscanthus was carried out as detailed in example 6. FTIR. analysis of different oil extract fractions can be seen in FIG. 16.

Example 2.7

(85) Microwave Extraction of Secondary Oil from Sitka Spruce with Capture of Highly Volatile Components

(86) Extraction of the secondary oil from Sitka Spruce was carried out as detailed in example 6. FTIR analysis of different oil extract fractions can be seen in FIG. 16.

Example 2.8

(87) Microwave Extraction of Oil from cellulose with Capture of Highly Volatile Components

(88) Extraction of the secondary oil from cellulose was carried out as detailed in example 6. FTIR analysis of different oil extract fractions can be seen in FIG. 16.

Example 2.9

(89) Use of Microwave Radiation to Increase the Calorific Value of Cellulose

(90) The use of microwave radiation to produce a char from cellulose was carried out using the following procedure.

(91) The cellulose (200 mg) was weighed out into a microwave tube containing a magnetic follower, and then sealed using the microwave tube lid. The sample was then placed in a laboratory microwave. The typical parameters used in the microwave are: power 300 W; temperature: 150 C.-300 C.; stirring: ON; cooling: OFF.

(92) The sample was then removed from the microwave and tested on a Stanton Redcroft STA 625 for any change in the calorific value. This was carried out using the following procedure.

(93) Cellulose (20 mg) that had been subjected to microwaves was, weighed out into a small sample container. To this sample, palladium oxide (20 mg) was added. The mixture was then emptied into a clean mortar and pestle and ground for approximately 10 to 15 minutes until a very fine powder formed. This powder was then poured into another clean sample vessel and tested within one hour of mixing.

(94) To an aluminium STA sample cup approximately 2.5 mg of the mixture was added, and then placed in the STA ready for testing. The conditions of analysis were 20 to 625 C. at 5 C. per minute in a flow of air (50 ml per minute). The calorific value results are shown in FIG. 17 along with those of chars produced under conventional pyrolysis conditions. The direct effect of the microwave irradiation on the cellulose in comparison to thermal activation under identical conditions is shown in FIG. 18. FIG. 19 shows the FTIR of cellulose before and after microwave irradiation. The .sup.13C MAS NMR of samples produced by microwave activation and conventional pyrolysis of similar calorific value are shown in FIG. 20.

Example 2.10

(95) Use of Microwave Radiation to Increase the Calorific Value of Hemi-Cellulose (Xylan)

(96) The use of microwave radiation to produce a char from hemi-cellulose (Xylan) was carried out using the following procedure and analysis outlined in Example 9. The calorific value results are shown in FIG. 21 along with those of chars produced under conventional pyrolysis conditions. The FTIR is shown in FIG. 19.

Example 2.11

(97) Use of Microwave Radiation to Increase the Calorific Value of Barley Dust

(98) The use of microwave radiation was used to increase the calorific value of barley dust was carried out and tested as detailed in example 9.

(99) The typical parameters used in the microwave are: power 300 W; time: 1-30 minutes; stirring: ON; cooling: OFF.

(100) The original STA profile before and after microwave processing for 30 minutes can be seen in FIGS. 23 and 24. The FTIR of the solid before and after microwave irradiation is shown in FIG. 19. Heat of oxidation values are recorded in FIG. 22.

Example 2.12

(101) Use of Microwave Radiation to Increase the Calorific Value of Rape Meal

(102) The microwave processing of rape meal for 30 minutes to increase the calorific value was carried out and tested as detailed in example 9. The original STA profile before and after microwave processing for 30 minutes can be seen in FIGS. 25 and 26, and heat of oxidation values recorded in FIG. 22. TGIR analysis of rape meal in low temperature (330 C.) show difference in volatile composition as can be seen in FIGS. 27 and 28.

Example 2.13

(103) Use of Microwave Radiation to Increase the Calorific Value of Miscanthus

(104) The microwave processing of Miscanthus to increase the calorific value was carried out and tested as detailed in example 9. Heat of oxidation values recorded in FIG. 22. FTIR analysis of the sample before and after microwave treatment can be seen in FIG. 19 to assess the change in functional groups in the solid state.

Example 2.14

(105) Use of Microwave Radiation to Increase the Calorific Value of Willow

(106) The microwave processing of willow to increase the calorific value was carried out and tested as detailed in example 9. Heat of oxidation values recorded in FIG. 22.

Example 2.15

(107) Use of Graphite to Change the Relative Yields of Solid Chars and Gas Products in the Presence of Microwave Irradiation

(108) The use of microwave radiation to form a char from cellulose using a microwave absorber was carried out using the following procedure. Cellulose (0.99 g) and graphite (0.01 g) were weighed out into a sample container. This mixture was then agitated until the graphite was evenly distributed throughout the cellulose.

(109) The cellulose/graphite mixture (200 mg) was weighed out into a microwave tube containing a magnetic follower, and then sealed using the microwave tube lid. The sample was then placed in a laboratory microwave. The typical parameters used in the microwave are: power 300 W; temperature: 270 C.; stirring: ON; cooling: OFF. The yield of char in comparison to char produced under the same conditions in the absence of graphite was seen to increase by 10% (wt/wt) as shown in FIG. 29.

Example 2.16

(110) Use of Microwave Radiation to Increase the Calorific Value of Pine Wood with Graphite

(111) The calorific value of Pine wood was increased using the method as detailed in example 15. The STA profiles before and after microwave irradiation can be seen in FIG. 30 and FIG. 31 respectively.

Example 2.17

(112) Use of Microwave Radiation to Increase the Calorific Value of Pelletised Cellulose

(113) The use of microwave radiation was used to increase the calorific value of cellulose using the following procedure.

(114) Powdered cellulose fibres were pressurised to produce pellets. Pellets of known density were placed in a microwave tube containing a magnetic follower, and then sealed using the microwave tube lid. The sample was then placed in a laboratory microwave. The typical parameters used in the microwave are: power 300 W; time: 1-30 minutes; stirring: ON; cooling: OFF. Analysis was carried out as detailed in example 9. The calorific value of the resulting pellet was found to be higher than loose powdered cellulose fibres processed under the same conditions.

Example 2.18

(115) Use of Microwave Radiation to Increase the Calorific Value of Rape meal on a 0.5 kg Scale

(116) The larger scale microwave processing of rape meal for 30 minutes up to a temperature of 250 C. was carried out by the following procedure. Rape meal (500 g) was weighed into the microwave vessel and placed in the microwave. The sample was heated under vacuum to remove the volatile components. The results for the char produced are shown in Tables 2.1 to 2.3.

Example 2.19

(117) Energy Efficiency of Microwave Torrefaction for Production of Increased Calorific Value Chars and Oils from Cellulose

(118) The use of microwave radiation to produce a char and oil from cellulose was carried out using the following procedure and analysis outlined in Example 9. Microwave temperature was varied between 180-300 C. FIG. 32 shows the percentage energy per gram of starting material which is maintained in the resulting char. For example, after microwave torrefaction of 1 g of cellulose at 270 C. gives a char yield of 42%, with calorific value 30 kJ/g. The total energy condensed in the char is 0.42*30 kJ/g=12.6 kJ/g. The calorific value of the cellulose starting material is approximately 15 kJ/g, therefore the percentage of the energy maintained within the char is 84%. The yield of oil was 7% with a calorific value of 19 kJ/g. Therefore, the energy of the starting material distributed into the oil product is 1.3 kJ/g or 8.7%. The total energy yield from the oil and char after microwave torrefaction at 270 C. is 93% of the starting material's potential. Up to approximately 220 C. (mass loss circa 50%), 100% of the energy is maintained in the char and oil. As can be seen in FIG. 32 these results are better than those found for conventional heating processes.

(119) The energy input required for the process is dependent on the mass of sample. FIG. 33 shows the energy input for the microwave torrefaction at 270 C. for different sample masses. The energy input decreases with mass of sample and for sample mass above 200 g the energy input was approximately 2 kJ/g.

Example 2.20

(120) Influence of Power and Temperature on Properties of Secondary Oil from Miscanthus

(121) The use of microwave radiation to produce a char and oil from cellulose was carried out using the following procedure and analysis outlined in Example 5. Maximum temperature reached was 150 C., using microwave power 300 W. The resulting oil was found to contain up to 30% water, and have a pH of 1-2. Oil prepared using microwave irradiation power of 150 W, reaching a maximum temperature of 120 C., a pH of 3-4 was measured with water content of less than 10%.

Example 3.1

(122) Microwave Processing of Wheat Straw (Standard Sample)

(123) 100 g of the wheat straw was placed in a large-scale laboratory microwave (Milestone) as shown in FIG. 35. The sample was heated up to 170 C. with a heating rate 10 K./min. The microwave experiment was carried out at a power of 1200 W. Experimental information about the mass balance for the microwave pyrolysis process is shown at Table 3.1. Bio-oil composition based on GC-MS analysis is shown in FIG. 36 and Table 3.2.

Example 3.2

(124) Microwave Processing of Wheat Straw in the Presence of 3% of Sulphuric Acid

(125) 100 g of wheat straw and 30 g of dilute sulphuric acid (10%) were weighed into the microwave vessel. This mixture was then agitated until the additive was evenly distributed throughout the biomass. The sample was then placed in a large-scale laboratory microwave and was heated up to 170 C. with a heating rate 10K/min. The microwave experiment was carried out at a power of 1200 W. Experimental information about the mass balance for the microwave pyrolysis process is shown in Table 3.1. Bio-oil composition based on GC-MS analysis is shown in FIG. 37 and Table 3.3.

Example 3.3

(126) Microwave Processing of Wheat Straw at the Presence of 1% of Sulphuric Acid

(127) 100 g of wheat straw and 10 g of dilute sulphuric acid (10%) were weighed into the microwave vessel. This mixture was then agitated until the additive was evenly distributed throughout the biomass. The sample was then placed in a large-scale laboratory microwave and was heated up to 170 C. with a heating rate 10K/min. The microwave experiment was carried out at a power of 1200 W. Experimental information about the mass balance for the microwave pyrolysis process is shown in Table 3.1.

Example 3.4

(128) Microwave Processing of Wheat Straw at the Presence of 3% of Hydrochloric Acid

(129) 3 g of HCl was adsorbed from the gas phase to 100 g of wheat straw. The sample was then placed in a large-scale laboratory microwave and was heated up to 170 C. with a heating rate 10K/min. The microwave experiment was carried out at a power of 1200 W. Experimental information about the mass balance for the microwave pyrolysis process is shown in Table 3.1. Bio-oil composition based on GC-MS analysis is shown in FIG. 38 and Table 3.4.

Example 3.5

(130) Microwave Processing of Wheat Straw at the Presence of 3% of Hydrochloric Acid

(131) 1 g of HCl was adsorbed from gas phase to 100 g of wheat straw. The sample was then placed in a large-scale laboratory microwave and was heated up to 170 C. with a heating rate of 10K/min. The microwave experiment was carried out at a power of 1200 W. Experimental information about the mass balance for the microwave pyrolysis process is shown in Table 3.1.

Example 3.6

(132) Microwave Processing of Wheat Straw at the Presence of 5% of Tri-n-Butylamine

(133) 100 g of wheat straw and 5 g of tri-n-butylamine were weighed into the microwave vessel. This mixture was then agitated until the additive was evenly distributed throughout the biomass. The sample was then placed in a large-scale laboratory microwave and was heated up to 170 C. with a heating rate of 10K/min. The microwave experiment was carried out at a power of 1200 W. Experimental information about the mass balance for the microwave pyrolysis process is shown in Table 3.1.4% of waxes were obtained in this experiment.

Example 3.7

(134) Microwave Processing of Wheat Straw at the Presence of 5% of Ammonia

(135) 100 g of wheat straw and 18 g of ammonium hydroxide solution (28%) were weighed into the microwave vessel. This mixture was then agitated until the additive was evenly distributed throughout the biomass. The sample was then placed in a large-scale laboratory microwave and was heated up to 170 C. with a heating rate of 10K/min. The microwave experiment was carried out at a power of 1200 W. Experimental information about the mass balance for the microwave pyrolysis process is shown in Table 3.1. Bio-oil composition based on GC-MS analysis is shown in FIG. 39 and Table 3.5.

Example 3.8

(136) Microwave Processing of Sawdust (Standard Sample)

(137) 100 g of sawdust was placed in a large-scale laboratory microwave (Milestone) as shown in FIG. 35. The sample was heated up to 200 C. with a heating rate of 10K/min. The microwave experiment was carried out at a power of 1200 W. Experimental information about the mass balance for the microwave pyrolysis process is shown in Table 3.1.

Example 3.9

(138) Microwave Processing of Sawdust at the Presence of 3% of Sulphuric Acid

(139) 100 g of sawdust and 30 g of dilute sulphuric acid (10%) were weighed into the microwave vessel. This mixture was then agitated until the additive was evenly distributed throughout the biomass. The sample was then placed in a large-scale laboratory microwave and was heated up to 200 C. with a heating rate of 10K/min. The microwave experiment was carried out at a power of 1200 W. Experimental information about the mass balance for the microwave pyrolysis process is shown in Table 3.1.

Example 3.10

(140) Microwave Processing of Lignin (Standard Sample)

(141) 100 g of lignin was placed in a large-scale laboratory microwave (Milestone) as shown in FIG. 35. The sample was heated up to 170 C. with a heating rate of 10K/min. The microwave experiment was carried out at a power of 1200 W. No change to the lignin was observed (see Table 3.1).

Example 3.11

(142) Microwave Processing of Lignin at the Presence of 5% of Ammonia

(143) 100 g of lignin and 18 g of ammonium hydroxide solution (28%) were weighed into the microwave vessel. This mixture was then agitated until the additive was evenly distributed throughout the biomass. The sample was then placed in a large-scale laboratory microwave and was heated up to 170 C. with a heating rate of 10K/min. The microwave experiment was carried out at a power of 1200 W. Experimental information about the mass balance for the microwave pyrolysis process is shown in Table 3.1.

(144) TABLE-US-00001 TABLE 3.1 Mass balance of what straw microwave pyrolysis. Temperature range Biomass ( C.) Yield (mass %) type MW Oil Organic N additive processing release Char oil Water Gas 1 Wheat Original 20-170 C. 90-120 C. 29 21.1 36.4 13.5 2 straw H.sub.2SO.sub.4 20-170 C. 82-110 C. 44.4 7.3 32.9 15.4 (3%) 3 H.sub.2SO.sub.4 20-170 C. 85-115 C. 41.0 10.8 33.1 15.1 (1%) 4 HCl 20-170 C. 70-90 C. 31.8 22.1 27.1 19 (3%) 5 HCl 20-170 C. 75-110 C. 30.3 21.2 31.8 16.7 (1%) 6 Tri-n- 20-170 C. 80-110 C. 39.9 20.2 26.2 13.7 Butylamine 7 NH.sub.3 20-170 C. 70-100 C. 40.7 17.0 22.3 20 (5%) 8 Sawdust Original 100-200 C. 150-180 C. 32.7 26.1 27.7 13.5 9 H.sub.2SO.sub.4 20-200 C. 70-110 C. 42.5 5.0 18.4 34.1 (3%) 10 Lignin Original 30-170 11 NH.sub.3 30-170 95-152 32.5 8.6 45.3 13.6 (5%)

(145) TABLE-US-00002 TABLE 3.2 Chemical composition of wheat straw microwaved oil. Area No Compound Percentage RT 1 Acetic Acid 0.84 7.194 2 Furfural 0.50 14.194 3 2-Furanmethanol 0.57 16.057 4 1,2-Cyclopentanedione, 3-methyl- 1.64 22.769 5 Phenol 2.00 24.154 6 Phenol, 2-methoxy- 2.73 24.703 7 Phenol, 2-methyl- 1.16 26.002 8 Phenol, 3-methyl- 1.23 27.370 9 Phenol, 4-methyl- 1.50 27.455 10 Phenol, 2-methoxy-4-methyl- 1.38 28.657 11 4.55 28.983 12 Phenol, 4-ethyl-2-methoxy- 1.57 31.701 13 1,4: 3,6-Dianhydro-.alpha.-d-glucopyranose 1.27 32.943 14 Benzofuran, 2,3-dihydro- 10.66 33.715 15 Phenol, 2,6-dimethoxy- 4.54 35.586 16 Phenol, 2-methoxy-4-(1-propenyl)- 2.84 38.196 17 Vanillin 1.13 38.980 18 Hydroquinone 1.44 39.185 19 Ethanone, 1-(4-hydroxy-3-methoxyphenyl)- 0.92 41.566 20 4-Methyl-2,5-dimethoxybenzaldehyde 2.45 42.779 21 Homovanillyl alcohol 1.62 43.174 22 L-glucosan 27.87 46.309 23 Phenol, 2,6-dimethoxy-4-(2-propenyl) 3.71 46.636 24 Ethanone, 1-(4-hydroxy-3,5- 1.07 49.456 dimethoxyphenyl)- 25 Desaspidinol 1.30 50.641 26 n-Hexadecanoic acid 0.75 51.871

(146) TABLE-US-00003 TABLE 3.3 Chemical composition of wheat straw microwaved oil prepared in the presence of H.sub.2SO.sub.4 Area No Compound Percentage RT 1 Acetic Acid <0.5 7.325 2 Furfural <0.5 14.220 3 1,2-Cyclopentanedione, 3-methyl- 0.59 22.769 4 Phenol 1.99 24.159 5 Phenol, 2-methoxy- 2.25 24.709 6 Phenol, 2-methyl- 1.07 26.008 7 Phenol, 4-methyl- 1.77 27.415 8 Phenol, 3-methyl- 0.99 27.495 9 L-glucosenone 23.63 28.640 10 Phenol, 2-methoxy-4-methyl- 1.91 28.680 11 Phenol, 4-ethyl- 0.67 30.597 12 Phenol, 4-ethyl-2-methoxy- 0.55 31.712 13 1,4: 3,6-Dianhydro-alpha-d-glucopyranose 6.69 33.046 14 2-Methoxy-4-vinylphenol/Benzofuran, 2,3- 1.06 33.715 dihydro- 15 Phenol, 2,6-dimethoxy- 0.54 35.575 16 Hydroquinone 0.72 39.197 17 Homovanillyl alcohol 0.64 43.174 18 Ethanone, 1-(4-hydroxy-3-methoxyphenyl)- 1.61 44.781 19 L-glucosan 20.64 46.355 20 Ethanone, 1-(4-hydroxy-3,5- 1.22 49.468 dimethoxyphenyl)- 21 Desaspidinol 2.21 50.664 22 Aspidinol 2.79 51.682 23 n-Hexadecanoic acid 1.19 51.900

(147) TABLE-US-00004 TABLE 3.4 Chemical composition of wheat straw microwaved oil prepared in the presence of HCl. Area No Compound Percentage RT 1 Acetic Acid <0.5 7.222 2 2-Furanmethanol <0.5 16.074 3 1,2-Cyclopentanedione 0.83 18.849 4 2(5H)-Furanone 0.67 21.264 5 1,2-Cyclopentanedione, 3-methyl- 1.54 22.964 6 Phenol 1.61 24.205 7 Phenol, 2-methoxy- 2.57 24.789 8 Phenol, 2-methyl- 0.67 26.031 9 Maltol 0.98 26.591 10 Phenol, 3-methyl- 1.44 27.427 11 Phenol, 4-methyl- 0.72 27.507 12 L-glucosenone 1.51 28.588 13 Phenol, 2-methoxy-4-methyl- 1.84 28.720 14 Phenol, 4-ethyl- 1.26 30.660 15 Phenol, 4-ethyl-2-methoxy- 1.41 31.758 16 1,4: 3,6-Dianhydro-alpha-d-glucopyranose 3.11 33.320 17 2-Methoxy-4-vinylphenol/Benzofuran, 2,3- 2.80 33.812 dihydro- 18 Phenol, 2,6-dimethoxy- 4.30 35.718 19 Phenol, 2-methoxy-4-(1-propenyl)- 0.83 38.264 20 3-Hydroxy-4-methoxybenzoic acid 1.96 38.722 21 Hydroquinone 1.26 39.363 22 Ethanone, 1-(2,6-dihydroxy-4- 0.90 41.039 methoxyphenyl)- 23 Ethanone, 1-(4-hydroxy-3-methoxyphenyl)- 0.93 41.680 24 Homovanillyl alcohol 2.33 43.328 25 Levoglucosan 35.46 47.665 26 Ethanone, 1-(4-hydroxy-3,5 0.93 49.605 dimethoxyphenyl)- 27 Desaspidinol 2.05 50.801 28 n-Hexadecanoic acid 0.93 52.025

(148) TABLE-US-00005 TABLE 3.5 Chemical composition of wheat straw microwaved oil prepared in the presence of NH.sub.3 Area No Compound Percentage RT 1 2-Furanmethanol 0.58 16.063 2 1,2-Cyclopentanedione 0.88 18.821 3 2(5H)-Furanone 0.61 21.213 4 1,2-Cyclopentanedione, 3-methyl- 1.67 22.872 5 Phenol 0.54 24.177 6 Phenol, 2-methoxy- 1.69 24.726 7 Phenol, 2-methoxy-4-methyl- 1.28 28.668 8 Phenol, 4-ethyl- 0.50 30.614 9 Phenol, 4-ethyl-2-methoxy- 1.13 31.724 10 1,4: 3,6-Dianhydro-.alpha.-d-glucopyranose 1.22 33.040 11 2-Methoxy-4-vinylphenol/Benzofuran, 2,3- 10.23 33.755 dihydro- 12 Phenol, 2,6-dimethoxy- 3.93 35.632 13 Phenol, 2-methoxy-4-(1-propenyl)- 1.49 38.218 14 Hydroquinone 1.33 39.237 15 Homovanillyl alcohol 1.00 43.219 16 Levoglucosan 46.44 46.922 17 Ethanone, 1-(4-hydroxy-3,5- 0.92 49.508 dimethoxyphenyl)- 18 Desaspidinol 2.74 50.698 19 n-Hexadecanoic acid 0.48 51.900