Patent Publication Number: US-2017349848-A1

Title: Slurry suspension comprising torrefied wood particles

Description:
FIELD OF THE INVENTION 
     The present invention relates to the field of slurry suspensions comprising carbonaceous material particles intended to be used as a liquid combustible. 
     STATE OF THE ART 
     In order to reduce the emission of sulphur from the combustion of fuel, which pollutes the environment, and be compatible with the Regulations relating to fuel consumption, oil refineries rendered available low sulphur content fuel, made up with refined heavy fuel of diesel fuel. However, due to a costly process, these fuel alternatives are usually more expensive than the less refined ones. 
     In addition, because of the expected shortage of crude oil due to the decline in natural reserves, it is more than ever urgent to find some efficient alternatives to reduce the portion of fossil-based energy sources. 
     Some alternatives to further refined fuel have consisted in replacing fossil-based combustible with biofuels, which development usually aims to design new catalytic process to convert solid biomass into liquid fuel. However, this disruptive process usually suffers for competitive price to make biofuel or biofuel from biomass. 
     Some other alternatives were recently proposed to increase the renewable fuel part in fuel compositions. For example, a technology based on a coal/water slurry (CWS), for which the coal is dispersed into water, provides a liquid fuel compatible with existing liquid boilers. 
     However, the disadvantage of coal/water slurries is that the water is inert to combustion, and therefore reduces the gross calorific value of aqueous coal or biocoal suspensions. 
     Another alternative that may be explored is the use of torrefied biomass for producing renewable energy with cost-competitive aspects and mainly for transportation regarding the high energy density material compared to white untorrefied biomass. 
     This “thermal processed biomass” offers interesting properties, such as low sulphur content, low nitrogen content, and excellent combustion properties. 
     Furthermore, torrefied biomass is an inert material as compared to untorrefied, white, biomass and the material get hydrophobic properties due to the loss of oxygen during the torrefaction process. 
     There is still a need in the art for the provision of liquid combustible formulations resulting in low sulphur emission, for which the fossil-based energy source accounts for only a reduced portion. 
     More particularly, because carbonaceous materials offer good combustion properties, there is still a need in the art for the provision of suspension comprising said carbonaceous materials in a liquid vehicle, said suspension being homogeneously and stably dispersed. 
     Further, there is still a need in the art for providing liquid combustible formulations that are compatible with the existing systems, such as engines and boilers. 
     SUMMARY OF THE INVENTION 
     A first aspect of the invention relates to a slurry suspension comprising: 
     (a) carbonaceous material particles having an average diameter D 50  comprised between 0.1 μm and 200 μm; 
     (b) a non-ionic surfactant; 
     (c) an aqueous phase; and 
     (d) an organic phase. (REV 1) 
     Another aspect of the invention relates to a method for the preparation of a slurry suspension according to the invention comprising the steps of: 
     i. mixing at least ingredients (b), (c) and (d) to form an emulsion; 
     ii. mixing ingredient (a) with the emulsion obtained in step i. to form a slurry suspension. (REV 16) 
     Another aspect of the invention relates to a method for generating power comprising combustion of the slurry suspension according to the instant invention. (REV 18) 
     A still another aspect of the invention relates to a use of a non-ionic surfactant to stabilize an emulsion comprising carbonaceous material particles having an average diameter D 50  comprised between 0.1 μM and 200 μm. (REV 19) 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The inventors surprisingly found that carbonaceous material particles may be added to an emulsion, in particular an oil-in-water emulsion, in order to obtain a stable and homogeneously dispersed slurry suspension that can be further used as a liquid biofuel for combustion. 
     The emulsion, in particular an oil-in-water emulsion, is stabilized by the presence of a non-ionic surfactant. 
     Slurry Suspension 
     Hence, a first aspect of the invention relates to a slurry suspension comprising: 
     (a) carbonaceous material particles having an average diameter D 50  comprised between 0.1 μm and 200 μm;
 
(b) a non-ionic surfactant;
 
(c) an aqueous phase; and
 
(d) an organic phase. (REV 1)
 
     Within the scope of the invention the term “suspension” refers to a system comprising carbonaceous material particles, i.e. a solid material, dispersed in a liquid phase comprising an aqueous phase, an organic phase and a non-ionic surfactant, in particles of larger than colloidal size. 
     In certain embodiments, the term “suspension” refers to a system comprising an emulsion, i.e. a liquid phase, in which are dispersed the carbonaceous material particles (emulsion state). 
     In certain embodiments, the term “suspension” refers to a system wherein an aqueous liquid phase and an organic liquid phase are separate phases and do not form an emulsion; the carbonaceous material particles being dispersed in these liquid phases (non-emulsion state). 
     Within the scope of the present invention, the term “about” refers to a value that may vary from +/−10% from said mentioned value. 
     Carbonaceous Material Particles 
     Within the scope of the instant invention, the term “carbonaceous material” refers to a material containing a large content of carbon. 
     The carbon content of carbonaceous material particles useful for the present invention typically exceeds 30 wt. %, based on the total weight of the carbonaceous material particles; it is often above 40 wt. %. It is preferably above 45 wt. %, more preferably above 50 wt. %, based on the total weight of the carbonaceous material particles. On the other hand, it is typically of at most 90 wt. %, and often of at most 80 wt. %, based on the total weight of the carbonaceous material particles. It can be of at most 70 wt. % or even of at most 60 wt. %, based on the total weight of the carbonaceous material particles. Certain useful ranges for the carbon content of carbonaceous material particles useful for the present invention are either from about 40 wt. % to about 80 wt. %, or from about 45 wt. % to about 75 wt. %, based on the total weight of the carbonaceous materials particles. The carbon content of the carbonaceous material particles can be determined by any method known to the skilled person. For example, it can be determined by drying the carbonaceous material particles for 12 h at 100° C. in an oven (to remove water and other volatiles), then keeping the dried particles in a dessicator (to avoid water pickup), then burning the carbonaceous materials particles in a burning oven under conditions capable of converting essentially the whole (when not, the whole) carbon content of the carbonaceous materials particles into carbon dioxide, then quantifying the C content (through the CO 2  formed by the combustion) by infrared detection. 
     In one embodiment, the carbonaceous material particles are selected in a group comprising a vegetal biomass, a coal, a coke, a graphite, a char, a biocoal and a mixture thereof (REV 3) 
     According to the present invention, a vegetal biomass comprises ligno-cellulosic fibers, and may be provided by any plant, wood and crop susceptible to provide suitable biomass. 
     Plants such as miscanthus, switchgrass, hemp; woods such as poplar, bamboo, eucalyptus, oil palm, willow, pine, oak, gum, aspen, beech, coconut tree and spruce; and crops such as corn, sorghum, sugarcane and beet are suitable for implementing the instant invention. 
     In certain embodiments, the vegetal biomass is selected in a group comprising a plant or a part thereof, e.g. leave, stem, root, including a crop or a part thereof; a wood, a wood chip or a wood sawdust; a straw; a bark; a grass; a forestry residue; an agricultural waste such as corn cobs, corn stover, corn stalk, wheat straw, bamboo grass, vine shoot, sugar cane bagasse, sorghum bagasse, almond shell, sunflower seed hull and a mixture thereof. 
     In certain embodiments, the vegetal biomass has been subjected to a treatment in order to remove its water content, such treatment being a dry heat treatment, steam explosion, vacuum evaporation, hydrothermal carbonization, or any suitable treatment known from the state of the art. 
     A dry heat treatment method may encompass a treatment of the starting biomass at a temperature below 200° C. to a maximum temperature of 500° C., for a period of time from several minutes to several hours. 
     In certain embodiments, the dry heat treatment consists of torrefaction, which is performed at a temperature ranging from about 280° C. to about 320° C., for a period of time ranging from 1 min to 15 min, preferably from 2 min to 8 min. 
     In certain preferred embodiments, the vegetal biomass is a torrefied vegetal biomass, preferably torrefied wood particles. (claim  4 ) 
     In certain embodiments, the carbonaceous material is coal, such as anthracite, semi-anthracite, charcoal, solvent refined coal, medium and high-volatile bituminous, sub-bituminous, and lignite coals. 
     In certain embodiments, the carbonaceous material is coke, such as petroleum coke, high temperature coke, foundry coke, low temperature coke, medium temperature coke, pitch coke, or any product obtained by carbonization of coal, pitch, petroleum residues, and certain other carbonaceous materials. 
     In certain embodiments, mixtures of coal and petroleum coke can be used in this invention. 
     When referring to “carbonaceous material particles”, one may understand that said particles have low water content or are water-less. By “low water content”, one may understand a water content that is at most 20% in weight as compared to the weight of the starting material. Hence, at most 20% in weight of water encompasses a water content of 0%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% and 20% in weight as compared to the weight of the starting material. 
     Within the scope of the invention, the expression “carbonaceous material particles” refers to particles of a carbonaceous material in a solid state. 
     The carbonaceous material particles encompassed by the invention are obtained after a fine wet or dry grinding of the carbonaceous material, using a grinding mill. When performing a wet grinding, the carbonaceous material particles may be further handled as to undergo a dry heat treatment intended to reduce its water content to a maximum of 20%. Oppositely, when performing a dry grinding, the carbonaceous material particles according to the invention have a water content of a maximum of 20% in weight as compared to the weight of the starting material. 
     In certain embodiments, the carbonaceous material particles provide the size distribution as follows:
         D 10  is comprised between 1 and 50 μm, and   D 90  is comprised between 50 and 500 μm. (REV 5)       

     Within the scope of the invention, the size of the particles may be measured by any suitable mean known from the state of the art. 
     In preferred embodiments, the size distribution of the particles is measured by the mean of laser diffraction by dry dispersion, respecting the principles and basic rules set out in ISO 13320:2009 (E). 
     In practice, the analysis is performed using a Helos H1302 laser diffraction sensor (Sympatec, Germany). The detector of the focal length is selected so that its pass band covers the size range of the carbonaceous material particles to be analysed. For example, when analysing a milled torrefied biomass, R4 detector (0.5 μm to 350 μm) is particularly well adapted. 
     The carbonaceous material particles are dispersed in a stream of dry nitrogen under pressure using a dry dispersing unit (Rodos, Sympatec, Germany). 
     The optimum operating conditions are sought experimentally to obtain a good dispersion of particles, without crushing in the ejector. In practice, when analysing carbonaceous material particles in the form of ground torrefied biomass, the nitrogen pressure is about 100 kPa (1 bar) and the depression represents about 4 kPa (40 mbar). 
     The carbonaceous material particles are fed using a vibrating chute. The feed rate is adjusted so as to obtain an optical concentration between 2% and 10%. In practice the total mass of the sample containing the carbonaceous material particles to be analysed ranges from about 1 g to about 10 g, preferably about 5 g. 
     Laser diffraction data were acquired and analysed using the Windox 5 software (Sympatec, Germany). 
     In one embodiment, the carbonaceous material particles represent between 5% to 50% by weight of the total weight of the suspension. (REV 6) 
     Non-Ionic Surfactant 
     Within the scope of the present invention, a non-ionic surfactant may be selected in a group comprising ether-based non-ionic surfactants, ester-based non-ionic surfactants, amine-based or amide-based non-ionic surfactants and fluro-surfactants. (REV 7) 
     a) Ether-Based Non-Ionic Surfactants 
     Among the ether-based non-ionic surfactants, one may cite ether of carboxylic acids-based non-ionic surfactant, alcohol-based non-ionic surfactant, oside-based non-ionic surfactants, fatty alcohol-based non-ionic surfactants and silicone non-ionic surfactants. 
     Non-ionic emulsifiers of interest in accordance with the present invention may be represented by ether of carboxylic acids of formula (1) as follows: 
       R1-O—(R2-O) y -CH2-COOH  (1),
 
     wherein R1 is C8-C20 alkyl, C8-C20 alkyl phenyl or C8-C20 alkenyl, R2 is C2-C10 alkylene, for example —CH2-CH2-, —CH2-CH2-CH2- or a mixture thereof, and y ranges from 2 to 50. 
     In certain embodiments, ether of carboxylic acids are represented by a compound of formula (1), wherein R2 is a C2 or C3 alkylene. 
     In particular, ether of carboxylic acids-based non-ionic surfactants are preferably represented by polyoxyethylene-based non-ionic surfactants (—(CH2-CH2-O)—), polyoxypropylene-based non-ionic surfactants (—(CH2-CH2-CH2-O)—), polyoxyethylene-polyoxypropylene-based non-ionic surfactants. 
     A polyoxyethylene-based nonionic surfactant may comprise a polyoxyethylene alkyl ether, a polyoxyethylene alkyl phenyl ether, a polyoxyethylene polyoxypropylene alkyl ether. 
     Among polyoxyethylene alkyl ethers, one may cite compounds such as polyoxyethylene cetyl ether, polyoxyethylene lauryl ether, polyoxyethylene octyl ether, polyoxyethylene oleyl ether, polyoxyethylene stearyl ether, polyoxyethylene isostearyl ether. 
     Among polyoxyethylene alkyl phenyl ethers, one may cite compounds such as polyoxyethylene octylphenyl ether, polyoxyethylene nonylphenyl ether and dialkylphenoxy poly(ethyleneoxy) ethanol. 
     Among polyoxyethylene polyoxypropylene alkyl ether, one may cite compounds such as polyoxyethylene polyoxypropylene cetyl ether, polyoxyethylene polyoxypropylene decyltetradecyl ether. 
     Alcohol-based non-ionic surfactant of interest in accordance with the present invention may be represented by alkoxylated alcohols. 
     Within the scope of the present invention, the term “alkoxylated” relies upon the presence of oxyalkylene units, for which the total number of these units generally ranges from 2 to 50, preferably from 3 to 25, preferably from 4 to 12, preferably from 2 to 10, most preferably from 2 to 6, or preferably from 10 to 50, most preferably from 10 to 35. 
     Alkoxylated alcohols of interest may be represented by a compound of the general formula (2) as follows: 
       R1-O—(R2-O) y -H  (2)
 
     wherein R1 is C6-C30 hydrocarbyl, R2 is C2-C10 alkylene, for example —CH2-CH2-, —CH2-CH2-CH2- or a mixture thereof, and y ranges from 2 to 50. 
     Preferably, alkoxylated alcohols may be represented by a compound of the general formula (3) as follows: 
       R3-O—(R2-O) y -H  (3)
 
     wherein R3 is C8-C20 alkyl or C8-C20 alkenyl, R2 is C2-C10 alkylene, for example —CH2-CH2-, —CH2-CH2-CH2- or a mixture thereof, and y ranges from 2 to 50, or 
     Alternatively, alkoxylated alcohols are of formula (4) as follows: 
       R4-φ-O—(R2-O) y -H  (4)
 
     wherein R4 is C4-C20 alkyl, in particular, R4 is octyl (C8) or nonyl (C9), φ is p-phenylene, R2 is C2-C10 alkylene, for example —CH2-CH2-, —CH2-CH2-CH2- or a mixture thereof, and y ranges from 2 to 50. 
     Similar alcohols can be obtained by replacing R4-φ in the above formula (4) by [2,4-6-tri-(t-butyl)]-phenyl. 
     Examples of alkoxylated alcohols suitable as a non-ionic surfactant, according to the invention, are the products of the condensation of (i) from 2 to 50 moles of at least one C2-C3 alkylene oxide, such as ethylene oxide, with (ii) a mole of an ethylenically saturated or unsaturated fatty alcohol, especially a C8-C20 alcohol chosen from lauryl alcohol, myristyl alcohol, palmityl alcohol, stearyl alcohol, oleyl alcohol, linoleyl alcohol, linolenyl alcohol, oxoalcohols and mixtures thereof. 
     Other examples of alkoxylated alcohols suitable as a non-ionic surfactant, according to the invention, are the products of condensation of (i) from 2 to 50 moles of at least one C2-C3 alkylene oxide, such as ethylene oxide, with a mole of n-octylphenol, n-nonylphenol and mixtures thereof. 
     Alcoxylated alcohols may be commercially available under the tradenames Brij® (Atlas Chemical Co.), Genapol® (Clariant) and Lutensol® (BASF). 
     Oside-based nonionic surfactants may comprise long chain alkyl polyglucosides, which are obtained by the condensation of a) a long chain alcohol containing from about 6 to about 25 carbon atoms, with b) a glucose or glucose containing polymer. In practice such a compound may be alkyl polyglycosides and alkyl polysaccharides, such as decyl glucoside, octyl glucoside or decyl maltoside. 
     In certain embodiments, the ether-based non-ionic surfactant is an alkoxylated phenol surfactant. (REV 8) 
     In certain embodiments, the alkoxylated phenol surfactant is chosen in a group comprising an alkoxylated alkylphenol, an alkoxylated alkylarylphenol, an alkoxylated sulfated and/or phosphate alkylphenol and alkoxylated sulfated and/or phosphate alkylarylphenol. (REV 9) 
     An alkoxylated phenol compound that is suitable comprises an oxyalkylene group that may be for instance an oxyethylene group, an oxypropylene group, or an oxyethylene/oxypropylene group (i.e. ethoxy-propoxylated group). 
     The number of oxyalkylene units, such as the number of oxyethylene (OE) units and/or oxypropylene (OP) units, in the alkoxylated phenol compound is normally between 2 and 100 depending on the desired HLB (hydrophile/lipophile balance). More particularly, the number of OE and/or OP units is comprised between 2 and 50. Preferably, the number of OE and/or OP units is comprised between 5 and 50. 
     Alkoxylated phenol compounds suitable for the present invention may comprise one, two or three linear or branched hydrocarbon group(s), preferably comprising from 4 to 50 carbon atoms, more preferably comprising from 4 to 12 carbon atoms, connected to the phenol group. This hydrocarbon group is preferably a hydrocarbon group chosen in the group consisting of an alkyl group, such as tert-butyl, butyl, or isobutyl; an aryl group; an alkylaryl group; and an arylalkyl group, which may comprise a heteroatom such as N, O or S. The alkyl moiety of the alkylaryl group or the arylalkyl group may be a C1-C6 alkyl moiety. Hydrocarbon group may notably be represented by a phenyl group or a phenylethyl group. 
     Alkoxylated phenol compounds may also comprise a functional group connected to the alkoxylated chain, such as phosphate (PO4− M+), sulfate (SO4− M+), sulfonate (SO3− M+) or carboxylate (COO− M+). M+ may be a cation including but not limited to H+, Na+, NH4+, K+, or Li+. 
     Suitable salts are, for example, metal salts, such as alkali metal or alkaline earth metal salts, e.g. sodium, potassium calcium or magnesium salts, or salts with ammonia or an organic amine, such as morpholine, piperidine, pyrrolidine, a mono-, di- or tri-lower alkylamine, for example ethyl-, diethyl-, triethyl- or dimethyl-propylamine, or a mono-, di- or tri-hydroxy-lower alkylamine, for example mono-, di- or tri-ethanolamine. 
     Alkoxylated phenol compounds may notably be a compound of formula (5) as follows: 
     
       
         
         
             
             
         
       
     
     wherein:
         R1, R2 and R3 are, independently from each other, a hydrogen or a linear or branched hydrocarbon group, preferably comprising from 4 to 50 carbon atoms, preferably comprising from 4 to 12 carbon atoms;   R4 is a divalent linear or branched alkylene radical comprising from 2 to 8 carbon atoms, preferably 2 or 3 carbon atoms; R4 may be a mixture of several different alkylene radicals;   n is an integer comprised between 2 and 100, preferably comprised between 2 and 50;   R5 is H, OH, alkoxy group, phosphate (PO 4   − M + ), sulfate (SO 4   −  M + ), sulfonate (SO 3   −  M + ) or carboxylate (COO −  M + ); M +  if present is a cation including but not limited to H + , Na + , NH 4   + , K +  or Li + .       

     As expressed in formula (5), R1 R2 and R3 are hydrogen or linear or branched hydrocarbon group connected to the phenyl structure. R1 R2 and R3 may be, independently from each other, alkyl group, such as tert-butyl, butyl, or isobutyl; aryl group; alkylaryl group; or arylalkyl group, which may comprise a heteroatom such as N, O or S. The alkyl part of alkylaryl group or arylalkyl group may be a C1-C6 alkyl part. R1 R2 and R3 may notably be, independently from each other, phenyl group or a phenylethyl group. 
     When R5 is an alkoxy group, it may be for instance a C1-C6 alkoxy group, such as —OCH3, —OC2H5, —OC3H7, —OC4H9, —OC5H11, or —OC6H13. 
     Suitable alkoxylated phenol compounds may notably be chosen in the group consisting of:
         alkoxylated alkylphenol that may be e.g. a C 6 -C 16 -alkanol such as alkoxylated octylphenol, alkoxylated laurylphenols and alkoxylated nonyl phenol, such as polyethoxylated octylphenols and polyethoxylated nonylphenols;   alkoxylated alkylarylphenol that may be e.g. an alkoxylated mono-, di- or tristyrylphenol, such as polyethoxylated tristyrylphenol;   Alkoxylated sulfated and/or phosphate alkylphenol; and   Alkoxylated sulfated and/or phosphate alkylarylphenol, such as ethoxylated and/or propoxylated, sulfated and/or phosphated, mono-, di- or tristyrylphenols, ethoxylated polyarylphenol ether phosphate.       

     Tristyrylphenol ethoxylates, for other uses, are for instance disclosed by U.S. Pat. No. 6,146,570, published PCT patent application number WO 98/012921 and WO 98/045212, incorporated herein by reference. 
     Alkoxylated phenol compounds of the present invention may notably be chosen in the group consisting of nonylphenol ethoxylated with 2 OE units; nonylphenol ethoxylated with 4 OE units; nonylphenol ethoxylated with 6 OE units; nonylphenol ethoxylated with 9 OE units; nonylphenol ethoxy-propoxylated with 25 OE+OP units; nonylphenol ethoxy-propoxylated with 30 OE+OP units; nonylphenol ethoxy-propoxylated with 40 OE+OP units; nonylphenol ethoxy-propoxylated with 55 OE+OP units; nonylphenol ethoxy-propoxylated with 80 OE+OP units; di(1-phenylethyl)phenol ethoxylated with 5 OE units; di(1-phenylethyl)phenol ethoxylated with 7 OE units; di(1-phenylethyl)phenol ethoxylated with 10 OE units; tri(1-phenylethyl)phenol ethoxylated with 8 OE units; tri(1-phenylethyl)phenol ethoxylated with 16 OE units; tri(1-phenylethyl)phenol ethoxylated with 20 OE units; tri(1-phenylethyl)phenol ethoxylated with 25 OE units; tri(1-phenylethyl)phenol ethoxylated with 40 OE units; tri(1-phenylethyl) phenols ethoxy-propoxylated with 25 OE+OP units; ethoxylated and sulfated di(1-phenylethyl)phenol comprising 5 OE units; ethoxylated and sulfated di(1-phenylethyl)phenol comprising 7 OE units; ethoxylated and sulfated di(1-phenylethyl)phenol comprising 15 OE units; ethoxylated and sulfated di(1-phenylethyl)phenol comprising 16 OE units; ethoxylated and sulfated tri(1-phenylethyl)phenol comprising 16 OE units; and ethoxylated and phosphated tri(1-phenylethyl)phenol comprising 16 OE units. 
     In practice, alkoxylated phenol surfactants according to the invention may be selected among:
         Tristyryl phenol ethoxylates, such as the commercially available products Soprophor® BSU; Soprophor® CY8; Soprophor® S25 (Solvay);   Alcool Ethoxylates, such as the commercially available products Rhodasurf® LA 12/80; Rhodasurf 0 LA 12; Rhodasurf 0 BC 720; Rhodasurf 0 BC 630; Rhodasurf 0 BC 639 (Rhodia);   Alkyl Phenol Ethoxylate such as the commercially available products Igepal® RC 630; Igepal® DM 530; Igepal® RC 620; Igepal® CO 610; Igepal® CO 630; Igepal® CO 660; Igepal® CO 710; Igepal® CO 710 (Solvay).       

     In practice, silicone surfactants comprise polydimethylsiloxane that is modified on side-chain(s), one extremity, both extremities and combination thereof. As an example of modifications, the polydimethylsiloxane may be modified by a polyether group, such as a polyoxyethylene group or a polyoxyethylene polyoxypropylene group. 
     b) Ester-Based Non-Ionic Surfactants 
     Among ester-based non-ionic emulsifiers of interest, one may cite alkoxylated oils and fats. These compounds encompass ethoxylated and/or propoxylated derivatives of lanolin (wool fat) or of castor oil. Lanolin is the generic name of a wax containing a mixture of esters and polyesters of high-molecular-weight alcohols and fatty acids. Castor oil is a mixture of a triglyceride of fatty acids. 
     Other examples of ester-based non-ionic emulsifiers may be represented alkoxylated acids, such as the compounds represented by monoesters and diesters. 
     Monoesters of interest may be represented by a compound of the general formula (6) as follows: 
     
       
         
         
             
             
         
       
     
     wherein R1 is C 6 -C 30  hydrocarbyl, R2 is C 2 -C 10  alkylene, for example —CH 2 —CH 2 —, —CH 2 —CH 2 —CH 2 — or a mixture thereof, and y ranges from 2 to 50. 
     Preferably, monoesters may be represented by a compound of the general formula (7) as follows: 
     
       
         
         
             
             
         
       
     
     wherein R3 is C 8 -C 20  alkyl or C 8 -C 20  alkenyl, R2 is C 2 -C 10  alkylene, for example —CH 2 —CH 2 —, —CH 2 —CH 2 —CH 2 — or a mixture thereof, and y ranges from 2 to 50. 
     Examples of alkoxylated acids monoesters are the condensation products of from 2 to 50 moles (in particular, from 4 to 16 moles) of an alkylene oxide (such as ethylene oxide) with one mole of a saturated or unsaturated fatty acid chosen from lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid and linolenic acid. An example thereof is Deplastol® product which is a condensate of about 4-5 mol oxyethylene units with lauric acid and/or myristic acid (Cognis, Germany). Corresponding propoxylated and/or butylated fatty acids may also be included in the alkoxylated acids monoesters of interest. 
     Diesters of interest may be represented by a compound of the general formula (8) as follows: 
     
       
         
         
             
             
         
       
     
     wherein R1 and R3 are independently a C 6 -C 30  hydrocarbyl, R2 is C 2 -C 10  alkylene, for example —CH 2 —CH 2 —, —CH 2 —CH 2 —CH 2 — or a mixture thereof, and y ranges from 2 to 50. Preferably, diesters of interest may be represented by a compound of the general formula (9) as follows: 
     
       
         
         
             
             
         
       
     
     wherein R4 and R5 are independently C 8 -C 20  alkyl or C 8 -C 20  alkenyl, R2 is C 2 -C 10  alkylene, for example —CH 2 —CH 2 —, —CH 2 —CH 2 —CH 2 — or a mixture thereof, and y ranges from 2 to 50. 
     Other examples of ester-based non-ionic emulsifiers of interest may represented by alkoxylated glycol, such as alkoxylated ethylene glycol esters and alkoxylated propylene glycol esters. 
     Alkoxylated ethylene glycol esters may be represented by a compound of the general formula (10) as follows: 
     
       
         
         
             
             
         
       
     
     wherein R1 is C 8 -C 20  alkyl or C 8 -C 20  alkenyl, R2 is C 2 -C 10  alkylene, for example —CH 2 —CH 2 —, —CH 2 —CH 2 —CH 2 — or a mixture thereof, and y ranges from 2 to 50. 
     Alkoxylated propylene glycol esters may be represented by a compound of the general formula (11) as follows: 
     
       
         
         
             
             
         
       
     
     wherein R1 is C 8 -C 20  alkyl or C 8 -C 20  alkenyl, R2 is C 2 -C 10  alkylene, for example —CH 2 —CH 2 —, —CH 2 —CH 2 —CH 2 — or a mixture thereof and y ranges from 2 to 50. 
     Alkoxylated esters of monoglycerides, dialkoxylated esters of diglycerides and trialkoxylated esters of triglycerides may also be compounds of interest, said esters being the reaction products of glycerol, or one of its derivatives, with a carboxylic acid comprising from 8 to 20 carbon atoms and comprise in total from 6 to 60 oxyalkylene units. 
     Among the non limitating ester-based non-ionic surfactants, one may cite polyoxyethylene alkylesters, polyoxyethyleneglycerine aliphatic acid esters, polyoxyethylene castor oil, hydrogenated castor oil, polyoxyethylene sorbitol aliphatic acid esters, polyethylene glycols aliphatic acid esters, aliphatic acid monoglycerides, polyglycerine aliphatic acid esters, sorbitan aliphatic acid esters, polyoxyethylene sorbitan aliphatic esters, propylene glycol aliphatic acid esters, cane sugar aliphatic acid esters, polyethylene glycol fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbit fatty acid esters, glycerin fatty acid esters, polyoxyethylene glycerin fatty acid esters, polyglycerin fatty acid esters, propylene glycol fatty acid esters, polyoxyethylene castor oil, polyoxyethylene cured castor oil, polyoxyethylene cured castor oil fatty acid ester, sucrose fatty acid esters, polyoxyalkylenated fatty acid esters, oxyalkylenated alkyl polyglycosides, alkyl glucoside esters. 
     In particular, among polyoxyethylene glycerin fatty acid esters, one may cite polyoxyethylene hydrogenated castor oil, polyoxyethylene castor oil, polyoxyethylene glyceryl monostearate, polyoxyethylene glyceryl monooleate, and polyoxyethylene glyceryl monoisostearate. 
     Among polyoxyethylene sorbitan fatty acid esters, one may cite polyoxyethylene sorbitan monostearate and polyoxyethylene sorbitan monooleate. 
     Among polyoxyethylene sorbitol fatty acid esters, one may cite polyoxyethylene sorbitol monolaurate. 
     Among polyethylene glycol fatty acid esters, one may cite polyethylene glycol monostearate, polyethylene glycol monooleate and polyethylene glycol monolaurate. 
     c) Amine-Based or Amide-Based Non-Ionic Surfactants 
     Examples of amine-based non-ionic surfactants may be amine oxide surfactants of the general formula (11) as follows: 
     
       
         
         
             
             
         
       
     
     wherein the arrow is a conventional representation of a semi-polar bond (N + —O − ); and, R1, R2, and R3 may be aliphatic, aromatic, heterocyclic, alicyclic, or combinations thereof. In practice, R1 is an alkyl radical in C 8  to C 24 ; R2 and R3 are alkyl or hydroxyalkyl in C 1  to C 3  or a mixture thereof; R2 and R3 can be attached to each other, e.g. through an oxygen or nitrogen atom, to form a ring structure. 
     In certain embodiments, R1 is selected from the group comprising octyl, decyl, dodecyl, isododecyl, coconut and tallow alkyl di-(lower alkyl) radicals. 
     In practice, these compounds are known as octyldimethylamine oxide, nonyldimethylamine oxide, decyldimethylamine oxide, undecyldimethylamine oxide, dodecyldimethylamine oxide, iso-dodecyldimethyl amine oxide, tridecyldimethylamine oxide, tetradecyldimethylamine oxide, pentadecyldimethylamine oxide, hexadecyldimethylamine oxide, heptadecyldimethylamine oxide, octadecyldimethylaine oxide, dodecyldipropylamine oxide, tetradecyldipropylamine oxide, hexadecyldipropylamine oxide, tetradecyldibutylamine oxide, octadecyldibutylamine oxide, bis(2-hydroxyethyl)dodecylamine oxide, bis(2-hydroxyethyl)-3-dodecoxy-1-hydroxypropylamine oxide, dimethyl-(2-hydroxydodecyl)amine oxide, 3,6,9-trioctadecyldimethylamine oxide and 3-dodecoxy-2-hydroxypropyldi-(2-hydroxyethy)amine oxide. 
     Other examples of amine-based non-ionic emulsifiers of interest in accordance with the present invention may be represented by alkoxylated amines, such as dialkoxylated primary amines and monoalkoxylated secondary amines. 
     Dialkoxylated primary amines of interest may be represented by a compound of formula (12) as follows: 
     
       
         
         
             
             
         
       
     
     wherein R1 is C 8 -C 20  alkyl or C 8 -C 20  alkenyl, R2 and R3 independently are C 2 -C 10  alkylene, for example —CH 2 —CH 2 —, —CH 2 —CH 2 —CH 2 — or a mixture thereof, and y and y′ range independently from 2 to 50; 
     Monoalkoxylated tertiary amines may be represented by a compound of general formula (13) as follows: 
     
       
         
         
             
             
         
       
     
     wherein R1 and R3 independently are C 8 -C 20  alkyl or C 8 -C 20  alkenyl, R2 is C 2 -C 10  alkylene, for example —CH 2 —CH 2 —, —CH 2 —CH 2 —CH 2 — or a mixture thereof and y ranges from 2 to 50. 
     Among the amide-based non-ionic surfactants, one may cite aldobionamides, aliphatic acid alkanolamides, polyoxyethylene alkylamides, polyoxyethylene aliphatic acid amides. 
     In some embodiments, the alkanolamide surfactants include, but are not limited to, cocamide DEA, lauryl diethanolamide, lauramide DEA, cocamide DEA, lauramide DEA. 
     Other examples of amide-based non-ionic emulsifiers of interest in accordance with the present invention may be represented by alkoxylated alkanolamides, such as alkoxylated monoalkanolamides and dialkoxylated dialkanolamides. 
     Alkoxylated monoalkanolamides may be represented by a compound of formula (14) as follows: 
     
       
         
         
             
             
         
       
     
     wherein R1 is C 8 -C 20  alkyl or C 8 -C 20  alkenyl, R2 is C 2 -C 10  alkylene, for example —CH 2 —CH 2 —, —CH 2 —CH 2 —CH 2 — or a mixture thereof, and y ranges from 2 to 50. 
     Dialkoxylated dialkanolamides, may be represented by a compound of formula (15) as follows: 
     
       
         
         
             
             
         
       
     
     wherein R1 is C 8 -C 20  alkyl or C 8 -C 20  alkenyl, R2 and R3 independently are C 2 -C 10  alkylene, for example —CH 2 —CH 2 —, —CH 2 —CH 2 —CH 2 — or a mixture thereof, and y and y′ independently from each other range from 2 to 50. 
     d) Fluoro-Surfactants 
     In general, fluoro-surfactants may be characterized by a content of fluorine in the molecule, which might either arise from the copolymerization of a partially or fully fluorinated alkylene oxide with a non-fluorinated alkylene oxide or by reaction of fluorine containing reactants with poly(alkylene oxides) thus providing endgroups with a fluorine content. 
     In the first case the oligomer or polymer comprises, in addition to the oxyalkylene groups, a certain amount of respective groups having one or more fluorine atom, i.e. in the case of ethylene oxide as the alkylene oxide these compounds comprise —(CH2-CH2-O)— units and —(CH2-aXa-CH2-bXb-O)— units, wherein X represents fluorine and at least one of a or b represents an integer of at least 1. 
     In certain cases, fluoro-surfactants may be represented by a compound of the general formula (16) as follows: 
       F(CF 2 —CF 2 ) x —CH 2 —CH 2 —O—(CH 2 —CH 2 —O) y —R  (16)
 
     wherein R is H or an alkoxy group and x and y have a value in the range of from 1 to 50, preferably in the range of from 1 to 30 and particularly preferred x and y are at most 20. Products of this type having a weight average molecular weight of at most 2000, preferably at most 1500 and even more preferably at most 1000 are of special interest. The ratio of x to y (x/y) is not subject to specific restrictions and may be selected within a wide range. A number of fluoro-surfactants of this type is available from DuPont under the trade name Zonyl®). 
     Another group of fluoro-surfactants includes short chain molecules having six or less groups CF 2  and terminated at one end with fluorine and bound to a delivery system such as a polymer or surfactant as commercially available from Du Pont under the trade name Capstone®. 
     In certain embodiments, the non-ionic surfactant represents from 0.1% to 5% by weight of the total weight of the suspension. (REV 10) 
     In certain embodiments, the non-ionic surfactant has an HLB comprised between about 10 to about 14, preferably a HLB of about 12. (REV 11) 
     Non-ionic surfactant having an HLB ranging from about 10 to about 14 are hydrophilic, i.e. are easily dispersible in an aqueous phase. Aqueous phase 
     In one particular embodiment, the aqueous phase consists of water. 
     In certain embodiments, the aqueous phase comprises water and at least one hydrophilic additive. 
     A suitable hydrophilic additive may include, without limitation, mono-alcohols having 2 to 8 carbon atoms, such as ethanol and isopropanol, and polyols such as glycerol, glycols, pentylene glycol, propylene glycol, butylene glycol, isoprene glycol and polyethylene glycols such as PEG-8. 
     In certain embodiments, the at least one hydrophilic additive may represent from 0.01% to 10%, preferably from 0.1% to 1% by weight of the total weight of the suspension. 
     As compared to the coal/water slurry (CWS), the lower amount of aqueous phase contained in the suspension reduces the amount of material that is inert with respect to combustion, namely water. 
     In certain embodiments, the aqueous phase represents between 10 to 30% by weight of the total weight of the suspension. (REV 12) 
     Organic Phase 
     In certain embodiments, the organic phase is selected in a group comprising a fossil-based liquid or a derivative thereof, a biomass-based liquid, a synthetic organic liquid or a derivative thereof, and a mixture thereof (REV 13) 
     In certain embodiments, the fossil-based liquid is a petroleum-based liquid or a derivative thereof (REV 14) 
     In certain embodiments, a fossil-based liquid according to the invention may be crude oil petroleum and crude oil petroleum derivative products, e.g. resulting from its process by oil refineries. As an example product from an oil refinery one may cite diesel fuel, fuel oil, furnace fuel oil (FFO), gasoline, heavy fuel oil (HFO), intermediate fuel oil (IFO), jet fuel, marine diesel oil (MDO), marine fuel oil (MFO), marine gas oil (MGO), navy special fuel oil (NSFO) and mixture thereof. 
     In certain embodiments, a biomass-based liquid according to the invention may be algae biofuel, bioethanol, biodiesel, biofuel gasoline, biomethanol, coconut oil, green diesel, palm oil, vegetable oil and a mixture thereof. 
     In certain embodiments, a biodiesel that is suitable for the instant invention may comprise palm oil, namely a Malaysian biodiesel or a LOF biodiesel, which latter has been used in the examples herein. The said Malaysian liquid biodiesel composition comprises a biodiesel composition derived from palm stearin, a biodiesel composition derived from palm oil methylester and a biodiesel composition derived from waste cooking oil. 
     In certain embodiments, the organic phase comprises a synthetic fuel, notably obtained from biomass and/or fossil reagents. 
     Within the scope of the invention, the organic phase may comprise aliphatic hydrocarbons such as for instance hexane, heptane, octane or nonane; inert cycloaliphatic hydrocarbons such as cyclohexane, cyclopentane or cycloheptane; aromatic hydrocarbons such as benzene, toluene, ethylbenzene, xylenes, or liquid naphthenes; alcohols such as butanol, ethanol, methanol or propanol; and a mixture thereof. 
     As compared to the coal/water slurry (CWS), the presence of an organic phase contained in the suspension increases the amount of material that is prone to combustion. Hence, the slurry suspension according to the invention offers excellent combustion properties, in particular a good gross calorific value. 
     In certain embodiment, the organic phase represents between 50% and 75% by weight of the total weight of the suspension. (REV 15) 
     Emulsions 
     In one aspect of the invention the slurry suspension may be in the form of an emulsion, namely an oil-in-water (O/W) emulsion or a water-in-oil (W/O) emulsion. 
     An emulsion may be prepared according to the general knowledge known in the state of the art. In practice, the preparation of an emulsion may include preparing, separately, a homogeneous aqueous phase and a homogeneous organic phase. 
     In certain embodiments, the non-ionic surfactant having a HLB ranging from about 10 to about 14 is dispersed in the aqueous phase. 
     At this stage, a direct oil-in-water (O/W) emulsion may be prepared by introducing the organic phase into the continuous aqueous phase while stirring. A direct O/W emulsion is hence obtained and represents a discontinuous organic phase dispersed in a continuous aqueous phase. 
     Oppositely, a water-in-oil (W/O) emulsion, is obtained by introducing the aqueous phase into the organic phase by stirring. At the end of this process, the reverse W/O emulsion is therefore represented by a discontinuous aqueous phase dispersed in a continuous organic phase. Other known specific methods of preparation may also be employed. 
     In certain embodiments, said suspension is an oil-in-water emulsion. (REV 2) 
     In certain embodiments, the weight ratio of the aqueous phase to the organic phase is ranging from a ratio of 1/7.5 to a ratio of 1/1.65, preferably from a ratio of 1/4 to a ratio of 1/2. 
     In certain embodiments, when the non-ionic surfactant is mixed in the aqueous phase, the weight ratio of the non-ionic surfactant to the aqueous phase is ranging from a ratio of 1/100 to a ratio of 1/7, preferably a ratio of 1/25 to a ratio of 1/8. 
     These ratios are particularly suitable for providing a stable emulsion and for efficiently and homogeneously dispersing the carbonaceous material particles in the aqueous phase. 
     Additional Ingredient(s) 
     Suspension of the present invention may also comprise one or several additional ingredient(s), such as the usual ingredients known in the field. Non-limitating examples of such ingredients may be humectants, wetting agents, rheology additives bases, corrosion inhibitors, foam inhibitors, stabilizers and biocidal preservatives. 
     When present in the suspension, said additional ingredient(s) represent(s) from 0.001% to 5%, preferably from 0.01% to 1% by weight of the total weight of the suspension. 
     Methods 
     In another aspect, the invention relates to a method for the preparation of a slurry suspension according to the instant invention comprising the steps of: 
     i. mixing at least ingredients (b), (c) and (d) to form an emulsion; 
     ii. mixing ingredient (a) with the emulsion obtained in step i. to form a slurry suspension. (REV 16) 
     In certain embodiments, said emulsion is an oil-in-water emulsion. (REV 17) 
     In certain embodiments, said method for the preparation of a slurry suspension according to the instant invention comprises the steps of: 
     i1. mixing at least the non-ionic surfactant (b) and the aqueous phase (c); 
     i2. mixing the organic phase (d) to the mix obtained in step i1. to form an oil-in-water emulsion; 
     iii. mixing carbonaceous material particles (a) with the oil-in-water emulsion obtained in step i2. to form a slurry suspension. 
     In these embodiments, the non-ionic surfactant is preferably added in the aqueous phase prior to the formation of the emulsion, as non-ionic surfactants with a HLB ranging from about 10 to about 14 are prone to be easily dispersed in an aqueous phase. Moreover, it was observed that the presence of a non-ionic surfactant facilitates the dispersion of the carbonaceous material particles in the aqueous phase. 
     In certain embodiments, an oil-in-water emulsion is obtained as described above, and the carbonaceous material particles are dispersed in the continuous aqueous phase in between the droplets of the organic phase. 
     Without wishing to be bound to a theory, in the case of an oil-in-water (O/W) emulsion, the lipophilic moiety of the non-ionic surfactant may advantageously form interactions with the hydrophobic surface of the carbonaceous material particles, whereas the hydrophilic moiety of the non-ionic surfactant would ease the dispersion in a continuous aqueous phase. Therefore, the carbonaceous material particles are homogeneously dispersed into the continuous aqueous phase and their sedimentation within the emulsion is significantly delayed. 
     In addition, the fact that the carbonaceous material particles are dispersed in between the droplets of organic phase creates a surface tension that maintain the droplets of organic phase homogeneously dispersed into the continuous aqueous phase 
     For these reasons, the carbonaceous material particles may behave as a surfactant, as they keep the droplets homogenously dispersed into the continuous aqueous phase, and the coalescence of the organic phase is significantly delayed. 
     In another aspect, the invention relates to a method for generating power comprising combustion of the slurry suspension according to the instant invention (REV 18). 
     Uses 
     In another aspect, the invention also relates to the use of a non-ionic surfactant to stabilize an emulsion comprising carbonaceous material particles having an average diameter D 50  comprised between 0.1 μM and 200 μm. (REV 19) 
     In certain embodiments, said emulsion is an oil-in-water emulsion. (REV 20) 
     The inventors have observed that a suspension according to the invention is able to form a stable emulsion, for e.g. an oil-in-water emulsion for a period of time of at least 2 weeks. 
     However, after a longer period of time the suspension in the form of an emulsion may return to a state of a non-emulsion suspension, i.e. after sedimentation and/or separation of the aqueous phase and the organic phase, has/have occurred. The suspension may further be manipulated in a way to form a stable emulsion for another period of at least 2 weeks. 
     The stable emulsion according to the invention may be advantageously used in already available combustion engine, or with only minor changes of these existing engines. 
     Examples 
     Example 1: Preparation of Torrefied Wood Particles 
     The torrefied wood chips are obtained by torrefaction and chips have cm scale average size. Torrefied wood chips are grinded following a dry grinding protocol to obtain particles with an average size of 300 μm to 1 mm. These particles, in the form of a powder, are subsequently dried milled by using a Retsch ZM200 dry miller with the following features: grid 120 μM, speed 18000 rpm, 25° C., nitrogen purge, 80 g per batch in 10 min. At the end of the milling process, particles display a particle size distribution, measured with Sympatec laser diffraction sensors, as follows: D 10 =6 μm; D 50 =23 μm; D 90 =60 μm. 
     Example 2: Slurry Suspension Comprising Water/Diesel/Torrefied Wood Particles 
     A stable oil in water (0/W) emulsion is prepared at room temperature by first mixing 20% wt of water, 63% of diesel (Shell V-Power Diesel CAS number: 68334-30-5) and 2% wt of Soprophor® BSU (non-ionic surfactant). The fact that the surfactant (Soprophor BSU; HLB=12) is added to water it wets wood particles easily. 
     15% wt of torrefied wood particles according to example 1 (25 μm) are then added and mixed with the first mixture to obtain a stable dispersion. An oil-in-water (o/w) emulsion is obtained with the torrefied wood particles located in the continuous phase. It can be observed that the torrefied wood particles get caught between the droplets in the continuous phase, which prevents them from settling. At the same time, the torrefied wood particles seem to act as emulsifying agents, preventing the coalescence of the droplets. 
     The number of days until an emulsion was unstable was determined by visually inspecting each sample once a day. Emulsion based slurry was termed unstable if:
         Coalescence led to the formation of an oil layer at the top of the slurry.   Creaming led to phase separation so that a wood and water layer at the bottom of the vessel was formed.   Sedimentation led to a solids layer at the bottom of the vessel.       

     In this case, with 15% torrefied wood, 20% water and 2% Soprophor BSU, emulsion remains stable for a long period of time. Illustratively, the said slurry emulsion remains stable after a period of time of storage of two weeks or more. 
     The formulation of an emulsion made from torrefied wood, water and diesel, stabilized with the non-ionic surfactant is hence feasible.