EP2408937A1 - Procédé de transformation de polysaccharides dans un hydrate de sel fondu inorganique - Google Patents
Procédé de transformation de polysaccharides dans un hydrate de sel fondu inorganiqueInfo
- Publication number
- EP2408937A1 EP2408937A1 EP10708779A EP10708779A EP2408937A1 EP 2408937 A1 EP2408937 A1 EP 2408937A1 EP 10708779 A EP10708779 A EP 10708779A EP 10708779 A EP10708779 A EP 10708779A EP 2408937 A1 EP2408937 A1 EP 2408937A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- molten salt
- inorganic molten
- salt hydrate
- dehydration
- inorganic
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
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- C—CHEMISTRY; METALLURGY
- C13—SUGAR INDUSTRY
- C13K—SACCHARIDES OBTAINED FROM NATURAL SOURCES OR BY HYDROLYSIS OF NATURALLY OCCURRING DISACCHARIDES, OLIGOSACCHARIDES OR POLYSACCHARIDES
- C13K1/00—Glucose; Glucose-containing syrups
- C13K1/02—Glucose; Glucose-containing syrups obtained by saccharification of cellulosic materials
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
- C10L1/00—Liquid carbonaceous fuels
- C10L1/10—Liquid carbonaceous fuels containing additives
- C10L1/14—Organic compounds
- C10L1/18—Organic compounds containing oxygen
- C10L1/1802—Organic compounds containing oxygen natural products, e.g. waxes, extracts, fatty oils
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
- C10L1/00—Liquid carbonaceous fuels
- C10L1/10—Liquid carbonaceous fuels containing additives
- C10L1/14—Organic compounds
- C10L1/18—Organic compounds containing oxygen
- C10L1/182—Organic compounds containing oxygen containing hydroxy groups; Salts thereof
- C10L1/1822—Organic compounds containing oxygen containing hydroxy groups; Salts thereof hydroxy group directly attached to (cyclo)aliphatic carbon atoms
- C10L1/1826—Organic compounds containing oxygen containing hydroxy groups; Salts thereof hydroxy group directly attached to (cyclo)aliphatic carbon atoms poly-hydroxy
Definitions
- the present invention relates to a process for converting polysaccharides, in particular lignocellulosic biomass material, in an inorganic molten salt hydrate to platform chemicals.
- the invention relates further to polysaccharide conversion products that are poorly soluble in the inorganic molten salt hydrate, and are suitable for use as fuel additives and/or fuel substitutes.
- platform chemicals In view of environmental concerns, there is a need for platform chemicals from renewable resources.
- platform chemicals is used to describe chemicals that are versatile starting materials for making specialty chemicals, and include sorbitol (or glucitol, alcohol sugar of glucose), xylitol/arabinitol (sugar alcohols from xylose and arabinose) and isosorbide (dianhydro-D-glucitol) and anhydrosugars [1].
- Patents US 647,805 and US 607,091 describe such hydrolysis processes, the first being a concentrated acid hydrolysis and the second a diluted acid hydrolysis.
- the diluted acid hydrolysis processes have a low yield, but do not need much further processing (acid removal) to separate and use the glucose formed.
- concentrated acid processes have higher yields but present difficulties in sugar recovery / acid separation. Processes for acid neutralization and removal, concentration of syrup and precipitation of sugars are known to those skilled in the art.
- US Patent 4,452,640 discloses a process to dissolve and quantitatively hydrolyze cellulose to glucose without formation of degradation products, using ZnCb solutions. Dissolution was effected with salt solutions, with 60 to 80 wt% ZnC ⁇ being preferred, at sufficiently large contact time and temperatures of 70 to 180 0 C, preferably 100 to 145°C. After dissolution, it was claimed that lowering the ZnC ⁇ concentration (to 40 to 50 wt%) was further necessary prior to hydrolysis, to avoid glucose degradation, and subsequently HCI or a similar dilute acid was added to effect hydrolysis (down to pH ⁇ 2).
- European Patent Application EP 0 091 221 A teaches the hydrolysis of cellulose or starch in solubilization media comprising water, an inorganic acid and hydrated halide of aluminum, optionally containing and additional metal halide, with yields close to 100 %. Longer hydrolysis times than the necessary lead to a lower yield of glucose due to degradation.
- LiCI and CaCI 2 solutions were considered the most effective, ZnCI 2 , MgCI 2 and CaCI 2 being somewhat less effective, and FeCI 3 , SnCI 4 , NaCI, KCI, MnCI 2 , NiCI 2 , CuCI 2 , CoCI 2 and CdCI 2 being the least effective.
- Typical conditions were 60-90°C, 15 to 25 wt% of cellulose substrate, in a dissolution medium containing 5-40 wt% of CaCI 2 and 25-40 wt% of HCI, pressure of 4-7 bar to maintain a liquid phase, and reaction times of 10 to 20 minutes, yielding more than 85 wt% of glucose.
- Glucose the desired product of processes of cellulose hydrolysis, needs to be further separated from the concentrated salt media in such processes. Besides precipitation of part of the salt (CaCI 2 concentrated solutions, US 4,018,620), ion exchange and chromatographic methods (US 4,452,640 and [5]) or even electrodialysis [6] were considered.
- a desired product of glucose is sorbitol, a hydrogenation product of glucose.
- a further desired product of sorbitol is the dianhydro sorbitol, or isosorbide, which is a product of double dehydration of sorbitol.
- Methods for producing isosorbide involve the dehydration of sorbitol (D- glucitol) in acidic solutions. Protonation due to the presence of acid occurs preferentially at the primary glucitol hydroxyl group.
- the first internal dehydration step leads to 1 -4 anhydro-D-glucitol.
- the dehydration can also take place at the 3 and 6 positions, leading to the 3,6-anhydro isomer [9].
- Further dehydration of both isomers leads to the 1 ,4-3,6 dianhydro-D-glucitol, or isosorbide .
- Another possible first dehydration occurs at the 1 ,5 and 2,5 positions. In these positions no second intramolecular dehydration is observed, yielding the monoanhydride derivative.
- Another complicating problem is the possibility of intramolecular elimination of water between two molecules, leading to higher molecular oligomeric or polymeric units.
- Acidic catalysts mainly used in the dehydration of sorbitol are H 2 SO 4 , phosphoric acid, HCI and other acids such as p-toluene sulfonic, methanesulfonic acid.
- Solid catalysts can be used such as acidic ion exchange resins, zeolites, and sulfated zirconia.
- dehydration is effected under vacuum (WO 00/14081 ), or with a flux of inert gas to effect water removal (for instance, using nitrogen, as taught by US Patents 6,407,266 and 6,689,892).
- Temperature limits are 170 0 C in the presence of acid - above that significant char and tarring are to be expected, as US 6,831 ,181 teaches.
- US Published Patent Application 20070173654 teaches the use of a hydrogenation catalyst during dehydration of a (preferably anhydrous) sugar alcohol, in the presence of an acidic catalyst.
- the hydrogenation catalyst contains a metal selected from Pd, Pt, Ni, Co, Ru, Re, Rh, Ir and Fe, and a support, which is preferably carbon, or alternatively zirconia, titania, niobia, silica or tin oxide. It is also possible to employ bifunctional catalysts, combining acidic and hydrogenation functions.
- the pressure is lower than 35 bar, preferably less than 20 bar, or even less than 10 bar, and preferred temperatures range from 110 0 C to about 170 0 C.
- the same patent teaches the possibility of using hydrogen flow in the countercurrent mode, as a way of effecting further water removal.
- US Patent 6,013,812 teaches the use of hydrogenation and acidic catalysts in a hydrogen atmosphere to effect dehydration of polyols. Without claiming a particular catalyst, the authors used Pd/C and Ru/C and additional acids in the examples. In the presence of a catalyst, less than 1 wt% polymers, but significant amounts of low molar weight polyols were formed, products of metal catalyzed hydrogenolysis. Without acidic catalysts there is insufficient conversion of D-sorbitol. Raney Cu, Co/Cu/Mn, Raney Ni and Cr-Ni were also tested in the absence of acid, and in spite of a high conversion (hydrogenolysis) the formation of isosorbide was lower than 2 wt%.
- Claimed salts are the ones with ions selected from the group consisting of magnesium, manganese, iron, cobalt, nickel, copper, actinium, thorium, protactinium, uranium, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium.
- ions selected from the group consisting of magnesium, manganese, iron, cobalt, nickel, copper, actinium, thorium, protactinium, uranium, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium.
- the dehydration of D-glucitol is effected in a 33 wt% aqueous solution containing a metal chloride at a mole ratio of 0.05 to D-glucitol, together with a nickel hydrogenation catalyst, without additional acid, yielding hydrogenolysis products (1 ,2-propylene glycol, ethylene glycol, glycerin and mannitol) and monoanhydro and dianhydro-D-glucitol.
- DUCLOS et al. teach that heating D-glucitol in anhydrous pyridine chloride (ionic liquid) at 120 to 160°C for several hours (above 4h) lead to 1 ,4- anhydro-D-glucitol and, to a lesser extent, 1 ,4:3,6-dianhydro-D-glucitol. Surprisingly, the authors observed no 1 ,5 or 2,5 anhydro-D-glucitols.
- An object of the present invention is to solve or mitigate the above problems
- a process for the conversion of polysaccharides to anhydro polyols with minimized formation of byproducts comprising contacting the material with an inorganic molten salt hydrate, in a ratio molten salt hydrate to lignocellulosic material of 1 to 50 wt/wt, and subjecting the mixture to the sequential steps of: a) Hydrolysis: contacting the polysaccharide with a molten salt hydrate composition and an inorganic soluble acid; conditions being resulting acid molality of mixture from 0.1 to 2.0 molal, temperature from 50 to 150 0 C and LHSV from 0.2 to 2h "1 .
- molten salt hydrate compositions are, for example, molten salt hydrates comprising at least Zn, Ca or Li halides, or mixtures thereof, with a content of 40 to 80 wt% of salt in said composition.
- an additional transition metal salt is added to the molten salt hydrate solution.
- the molar ratio of additional salt to polyol, prior to step c) is from 0.01 to 5.
- Preferred additional transition metal salts are the salts of copper or nickel, preferably NiC ⁇ or CuC ⁇ .
- At least 50% of the inorganic soluble acid is removed after hydrolysis, prior to hydrogenation.
- the process feedstock is a lignocellulosic material containing cellulose, hemicellulose and lignin, with hemicellulose being removed prior to step a) by any of the means known in the art (such as extraction with hot water), whereby the lignin is separated after the hydrolysis step a), the main product being 1 ,4:3,6 dianhydro-D-glucitol (isosorbide).
- the feedstock comprises saccharose, such as raw saccharose from a sugar refinery; sugar cane or sugar beet residue containing residual sugar; and whole sugar cane or sugar beet biomass.
- saccharose such as raw saccharose from a sugar refinery
- sugar cane or sugar beet residue containing residual sugar such as sugar cane or sugar beet biomass.
- the process feedstock is a lignocellulosic material containing cellulose, hemicellulose and lignin, wherein the lignin is separated after the first a) hydrolysis step, and the products being the products of the dehydration of C5 and C6 polyols.
- the process feedstock is cellulose
- the main product is 1 ,4:3,6 dianhydro-D-glucitol.
- the hydrolysis step is conducted in the absence of a mineral acid.
- the dehydration step is conducted in a molten salt medium containing substantially one inorganic cation.
- the dianhydro sugars are converted in the inorganic molten salt medium to compounds that are less soluble in the inorganic molten salt medium, and can as a result be readily separated from the medium. Examples of such further conversion reactions are estehfication and etherification. The resulting products are suitable as fuel additives and/or fuel substitutes.
- An important advantage of the use of an inorganic molten salt hydrate medium is the fact that the feedstock may contain significant amounts of water.
- organic Ionic Liquids require the substantial absence of water, which makes them unsuitable for unrefined feedstocks, such as agricultural products and agricultural waste materials, which generally contain significant amounts of water.
- the reaction to isosorbide involves the generation of water.
- Inorganic molten salt hydrates maintain their solvent properties as water is produced in the reaction, whereas organic Ionic Liquids generally lose their solvent properties as water is generated in the reaction.
- FIGURE 1 is a scheme of a preferred embodiment of the process comprising the combined steps of dissolution and hydrolysis of cellulose, hydrogenation of glucose to sorbitol and dehydration to isosorbide in molten salt hydrate medium.
- FIGURE 2 is a graph illustrating the effect of increasing the salt concentration in the ZnC ⁇ molten salt hydrate media on the hydrolysis of cellulose, according to Example 2.
- FIGURE 3 is a graph illustrating the effect of time on the hydrolysis of cellulose in a ZnCb 70 wt% molten salt hydrate media, according to Example 3.
- FIGURE 4 is a graph illustrating the effect of hydrochloric acid on the hydrolysis of cellulose to glucose, according to Example 5, and on the hydrogenation of glucose to sorbitol, according to Example 6
- FIGURE 5 is a graph that illustrates the effect of increasing the salt concentration in the ZnC ⁇ molten salt hydrate media on the hydrogenation of glucose to sorbitol, according to Example 6.
- FIGURE 6 is a graph that illustrates the effect of reaction time on the dehydration of sorbitol in the ZnC ⁇ molten salt hydrate media in the presence of Copper chloride, according to Example 11.
- FIGURE 7 is a graph that illustrates the effect of different concentrations of additional salt (CuCb) on the dehydration of sorbitol in the ZnC ⁇ molten salt hydrate media, according to Example 12.
- the present invention relates to a process for the conversion of polysaccharides, such as lignocellulosic material components, to sugars, then polyols and finally to certain dehydration products, the conversion steps being effected in an inorganic molten salt hydrate medium.
- polysaccharides such as lignocellulosic material components
- the invention relates to the conversion of cellulose and starch to sorbitol and subsequently to dehydration products.
- cellulose Besides cellulose, hemicellulose is also a possible feedstock.
- Cellulose and starch are polymers of glucose units, linked respectively by ⁇ glucosidic bonds and ⁇ bonds.
- Hemicelluloses are polymers of C6 sugars, including glucose, mannose, galactose, and rhamnose, and C5 sugars such as xylose, and arabinose.
- a particularly desirable feedstock for the process of the invention is sugar- containing biomass material.
- sugar- containing biomass material examples include saccharose, such as raw saccharose from a sugar refinery; sugar cane or sugar beet residue containing residual sugar; and whole sugar cane or sugar beet biomass material.
- hemicelluloses are previously removed from the lignocellulosic material, as the separation of hemicellulose fraction from biomass is easily effected with hot water treatment or aqueous phase diluted acid hydrolysis. Hemicelluloses can be further fermented to produce ethanol.
- hemicellulose as may be present in the feedstock is left in the inorganic molten salt medium upon dissolution of the feedstock.
- the hemicellulose is then subjected to the conversion reactions of the process of the invention.
- a mixture of C6 and C5 (di)anhydro sugars is formed.
- a product mixture is obtained that is readily separated from the inorganic molten salt hydrate medium, and can be used as, for example, a fuel substitute or a fuel additive.
- lignocellulosic materials include wood pulp, bagasse (in particular sugar cane bagasse), sawdust, cotton linter, stover, corn, straw, grasses, paper, forestry residues, sugar beet pulp, agriculture residues, algae, among others.
- bagasse in particular sugar cane bagasse
- sawdust cotton linter
- stover corn
- straw grasses
- paper forestry residues
- sugar beet pulp agriculture residues, algae, among others.
- any feedstock having at least 20 wt%, preferably 40 wt% of cellulose is suitable.
- Lignocellulosic material is preferably pretreated to ensure a good contact with the molten salt hydrate media.
- Pretreatment may include comminution effected by cutting, crushing, grinding and/or rasping.
- crushers are used followed by grinders.
- comminution of the lignocellulosic biomass material is effected in the first step, before the contact with the molten salt hydrate medium.
- the comminution is effected during the contact with the molten salt hydrate medium.
- the water content of the mixture of the inorganic molten salt hydrate media and the lignocellulosic biomass material results in a total water content in the mixture such that the cellulose material is soluble in the inorganic molten salt hydrate media.
- the water content of the lignocellulosic material is lowered before contact with the salt hydrate media.
- a preferred inorganic molten salt hydrate medium has at least 40 wt% of ZnCb, more preferably 60 wt% of ZnC ⁇ , prior to the polysaccharide addition.
- the preferred salt content in salt hydrate medium is within the range of 60 to 85 wt%, not considering the biomass content.
- the salt content can be increased to compensate non-dried lignocellulosic material with high water content.
- a salt content higher than 85 wt% in the ZnC ⁇ media is not preferred, as the salt content may exceed the saturation concentration, which leads to precipitation of ZnC ⁇ from the salt media.
- 70 wt% ZnC ⁇ is the preferred inorganic molten salt hydrate
- other inorganic molten salt hydrates may be used, alone or in combination with ZnC ⁇ , such as other zinc halides (bromide, iodide), or halides of other metals known to dissolve or swell cellulose, such as CaCb and LiCI.
- At least one transition metal salt may be present in the inorganic molten salt hydrate to enhance dehydration in the sugar alcohol dehydration step.
- Preferable metal salts are transition metal halides, preferably chlorides.
- Useful transition metal salts are the chlorides of the groups of Cu, Ni, Co, Fe, Mn, Cr, V and Ti.
- Preferred additional metal salts are CuCb and NiC ⁇ .
- the dehydration step is carried out in the substantial absence of a transition metal salt.
- the dehydration step may be carried out in an inorganic molten salt medium containing substantially one inorganic cation.
- the ratio of inorganic molten salt hydrate media to polysaccharide or biomass is preferably from 1 to 50 wt/wt, more preferably from 5 to 20 wt/wt.
- the inorganic molten salt hydrate temperature prior to contact with the lignocellulosic material may be higher than the desired temperature in the hydrolysis step.
- the mixture of lignocellulosic biomass and inorganic molten salt hydrate may be heated after mixing. Means of heat transfer known in the art can be utilized for obtaining the conditions required for the several modes of the present invention.
- the desired temperature is the one optimal for hydrolysis.
- addition of a mineral acid is desired, as shown in the following examples. Any of a number of mineral acids can be used, such as hydrochloric acid, hydrofluoric, sulfuric, phosphoric, and the like. Hydrochloric acid is the preferred acid, as it can be easily removed from the molten salt hydrate media by flash distillation, or stripping with nitrogen, or other suitable means known in the art.
- the acid molality (mol acid per 1000 g of inorganic molten salt hydrate and acid mixture) is higher than 0.2 molal and lower than 2 molal, more preferably from 0.4 to 0.8 molal. Higher concentrations of acid than 2 molal may promote glucose degradation to undesirable compounds.
- the hydrolysis reaction is carried out in the substantial absence of a mineral acid.
- the advantage of this embodiment is that no subsequent removal of mineral acid is necessary.
- the hydrolysis reaction requires a reaction temperature of 85 0 C or higher.
- the hydrolysis temperature is such as to obtain a high hydrolysis rate, but a low degradation of glucose to undesired compounds.
- preferred temperatures are higher than 70 0 C (85 0 C if no acid catalyst is present), and lower than 150 0 C, more preferably higher than 90°C and lower than 120 0 C.
- added gases preferably oxygen-free gases, may be added to the reaction system as heat transfer media.
- the hydrolysis time, or residence time in the apparatus where the lignocellulosic material and molten salt hydrate and mineral acid are contacted, is such as to obtain full hydrolysis of polysaccharides, such as cellulose and hemicellulose, if present.
- the residence time should be from 10 to 180 minutes, preferably from 30 to 60 minutes.
- Equipments to effect the hydrolysis can be batch reactors, continuous stirred tank reactors (CSTR) or a sequence of 2 or more CSTRs, continuous tubular reactors, fluidized bed reactors (suspended biomass particles whose cellulose is being dissolved), screw reactors, rotating reactors with or without ball milling or any suitable means of contacting the phases.
- CSTR continuous stirred tank reactor
- continuous tubular reactors continuous tubular reactors
- fluidized bed reactors uspended biomass particles whose cellulose is being dissolved
- screw reactors rotating reactors with or without ball milling or any suitable means of contacting the phases.
- the whole process sequence can also be done in a batch way, but the continuous process is preferred. Advantages of a continuous process over a batch process are well known to one skilled in the art.
- the dissolution and hydrolysis convert the hydrolyzable polysaccharide material (cellulose and /or hemicellulose or starch) to C6 (and C5) monosaccharides (hexitols and pentitols sugars).
- the lignin can be fully separated from the inorganic molten salt hydrate and sugar solution.
- Suitable means to separate the insoluble lignin from the molten salt hydrate and sugar solution are filtration, centrifugation, decantation, use of hydrocyclones, settling, gas flotation, addition of an organic phase to which lignin would preferably interface, or a combination of these methods.
- a preferred method is centrifugation or the use of hydrocyclones, with and additional filtration to prevent any solid from being sent to further catalytic hydrogenation. Lignin is preferably further washed to remove salt still present in the solid cake, prior to further use.
- Lignin can be used as a heat source to the process, and as a way of producing hydrogen to be used in the subsequent process steps.
- Hydrogen can be generated by any suitable process known in the art, such as lignin pyrolysis, steam reforming, or electrolysis of water from electricity produced by burning lignin.
- acid in a preferred embodiment of the invention process, acid (if present) is removed prior to hydrogenation.
- acids have an inhibiting effect on the hydrogenation of glucose to sorbitol.
- separation of volatile acids such as hydrochloric acid is difficult, as it forms an azeotrope with water. Fortunately, the azeotrope is broken in inorganic molten salt hydrate solutions, such as the ZnC ⁇ concentrated solution preferred in the process of the present invention, as a result of which hydrochloric acid can be easily separated by flashing, distillation, countercurrent or concurrent stripping.
- Hydrolysis is carried out at a temperature sufficient to provide a significant gas phase fugacity of hydrochloric acid.
- Other non-volatile acids such as sulfuric or phosphoric acid can be removed by chemical treatment, preferably forming insoluble compounds.
- the volatile hydrochloric acid is the preferred acid for use herein.
- Hydrochloric acid can be removed in the same step as lignin removal, for example if flotation is used for lignin removal (with nitrogen or air, preferably nitrogen, acting as stripping gas and flotation agent).
- Hydrochloric acid can also be removed in the same step as hydrogenation, for example by effecting a countercurrent hydrogenation, where hydrogen is fed to the bottom of the reactor and the mixture of hydrochloric acid, glucose and molten salt hydrate is fed previously to the catalyst bed region - in this case a previous mass contact region with suitable mass contact devices can also exist. Hydrochloric acid is removed together with hydrogen at the top of the reactor. The hydrogen/hydrochloric acid mixture may be bubbled through water for hydrochloric acid removal. Suitable countercurrent contacting devices upstream from the reaction zone can be bubble cap trays, Raschig rings, structured packings, or a combination of contact and reaction structures, such as internally finned monoliths (IFM).
- IFN internally finned monoliths
- Hydrogenation temperature is such as to obtain a high hydrogenation rate but low degradation of glucose to undesired compounds.
- preferred temperatures are higher than 70 0 C and lower than 150 0 C, more preferably higher than 90°C and lower than 120 0 C.
- pressures higher than 10 bar preferably higher than 30 bar, more preferably higher than 50 bar, and temperatures lower than 120°C. Pressures higher than 200 bar are not economically advantageous.
- the hydrogenation may be carried out at a LHSV of 0.05 to 5 h-1 and a molar excess of hydrogen with respect to the sugars (monosaccharides) being reduced of at least 2, preferably at least 3-fold.
- Reaction is effected by contacting the molten salt hydrate and sugar solution with a catalyst.
- a preferred means for contact is a fixed bed catalyst.
- Alternative ways of contact are slurry reactors, expanded bed, moving beds - which can make it easier to replenish catalyst (and activity) continuously or intermittently.
- the preferred reactor is a trickle bed (or flooded bed) reactor, as the high catalyst holdup and the employed conditions do not result in significant catalyst deactivation.
- the inorganic molten salt hydrate can adsorb a significant part of the heat released during glucose hydrogenation, when the inorganic molten salt hydrate to biomass ratios of the invention are used. Additional procedures, such as product recycle, high gas / feed ratio can also be employed to minimize the heat increase due to glucose hydrogenation.
- Suitable hydrogenation catalysts are the catalysts well known in sugar hydrogenation, such as Ru/C, Raney Ni or Raney Cu, Ni supported on carbon or alumina.
- the active catalyst component is selected from the noble metals of the series Ru, Rh, Pd and Pt, or a transition metal of the series Cu, Cr, Co, Ni, Fe.
- the preferred catalyst is Ru/C, as it is known to be less prone to leaching.
- Suitable support materials include activated carbon, aluminum oxide, hydrotalcites, silicates, titanates, zirconates, and other metallic oxides such as SnO 2 , Bi 2 O 5 , Sb 2 O 5 , MoO 3 , WO 3 , mixed oxides such as SiO 2 -AI 2 O 3 SiO 2 -TiO 2 , AI 2 O 3 -ZnO, SiO 2 -ZrO 2 , SiO 2 - SnO 2 , SiO 2 - MoO 3 , SiO 2 -WO 3 , metallic salts such as AIPO 4 , FePO 4 , Zn 3 (PO 4 ) 2 , Mg 3 (PO 4 ) 2 , Ti 3 (PO 4 ) 4 , Zr 3 (PO 4 ) 4 .
- Basic oxides can also be used, such as MgO, BeO, La 2 O 3 , CeO 2 , Pr 2 O 3 , Nd 2 O 3 , SmO 2 , ZrO 2 .
- Homogeneous, non-supported catalysts can also be used, but they are usually not stable at the temperatures, preferably higher than 200 0 C, required for the dehydration step.
- the desired reaction product is a product with at least 98 wt% of glucose or monosaccharide sugars present, available for conversion to sorbitol or the correspondent sugar alcohols.
- C6 sugars are hydrogenated to hexitols and C5 sugars are hydrogenated to pentitols,
- Another possible embodiment of the invention is a one-pot combination of hydrolysis and hydrogenation, as it is possible to hydrogenate glucose to sorbitol even in the presence of the acid necessary for hydrolysis.
- dehydration is performed to produce the desired isosorbide or correspondent (di) anhydro sugar alcohol.
- One or two dehydrations are possible from the starting sugar alcohol, to first form an anhydro sugar alcohol and finally a dianhydro sugar alcohol.
- the inorganic molten salt hydrate and sugar alcohols solution is sent to an additional reactor to effect the dehydration of sugar alcohols (sorbitol) to isosorbide or the correspondent anhydro sugar alcohols.
- Temperatures from 160 to 320 0 C can be used, preferably from 220 to 280 0 C.
- Pressures of 0.1 to 10 MPa are suitable, preferably from 2 to 6 MPa.
- Preferably hydrogen atmosphere is employed, as it advantageously increases the yield of isosorbide.
- Additional conditions are LHSV from 0.1 to 5 h-1.
- the product of the hydrogenation step - inorganic molten salt hydrate and sugar alcohols solution and remaining hydrogen are sent to the dehydration reactor.
- Conventional methods can be used to increase the temperature to the desired temperature range. Methods such as heat exchange with reaction product, furnaces, heating devices in the reactor, tube reactor, addition of a hot recycle flow and the like can be used, as long as the disclosed pressure, temperature, residence time (LHSV) are used. Full conversion of sorbitol is attained in the disclosed conditions.
- a transition metal salt is used together with the inorganic molten salt hydrate and sorbitol or polyol solutions.
- the molar ratio of additional salt cation to polyol is from 0.01 to 5, preferably 0.1 to 1.0, more preferably 0.2 to 0.5.
- the combination of the inorganic molten salt hydrate media and the additional transition metal salt results in increased selectivity and conversion. It is also believed that the presence of hydrogen during the dehydration step further enhances the dehydration activity and selectivity. It is possible to form some amount of reduced metal during this step. Such metals can be separated by filtration and can be converted again to salt by contact with acid. In any event, the preferred additional salts, pressure and temperature are such that the formation of reduced metals is minimized.
- the resulting isosorbide or equivalent anhydro sugar alcohols can be separated from the molten salt hydrate media by known separation techniques.
- a preferred separation technique is extraction with hydrocarbons at temperatures higher than 100 0 C, where the solubility of isosorbide is significant.
- the hydrocarbons are then cooled and the isosorbide or equivalent anhydro sugar alcohols are recovered by precipitation.
- a preferred hydrocarbon to effect the separation is xylene.
- Another preferred separation technique involves the vaporization of isosorbide, which has a vapor pressure significantly higher than sorbitol or anhydrosorbitol.
- Stripping with water vapor or air at low pressure and high temperature can be used. In this case it is necessary to work at a temperature higher than the melting temperature of the (molten) salt, as water will also be removed. For ZnC ⁇ the melting point is 275°C.
- water can be re-added to the inorganic molten salt hydrate media. It is also possible to use an additional salt such as KCI in the hydrated inorganic molten salt to lower the melting point of anhydrous molten salt ZnC ⁇ .
- the pentitols (originating from the hydrolysis of hemicellulose) dehydration yields just monoanhydrides, which are more difficult to separate, and thus it is preferred to effect first a hemicellulose removal, prior to contacting the cellulose feedstock with the inorganic molten salt hydrate media.
- the dianhydro sugars and/or anhydro sugars are dehvatized in the inorganic molten salt hydrate medium.
- the purpose of this dehvatization is to render the (di) anhydro sugars less polar, and hence less soluble in the inorganic molten salt hydrate medium. In general, this is achieved by removing or blocking free hydroxyl moieties in the (di) anhydro sugar molecule.
- One example of a suitable derivation reaction is a further dehydration of the (di) anhydro sugar molecule.
- Another example is reacting the hydroxyl moieties with a suitable reactant, such as a dialkyl carbonate, an alcohol, or a carboxylic acid.
- a suitable reactant such as a dialkyl carbonate, an alcohol, or a carboxylic acid.
- suitable dialkyl carbonates include dimethyl carbonate and diethyl carbonate.
- suitable carboxylic acids include formic acid, acetic acid, and acetic anhydride. It will be understood that acetic anhydride is, strictly speaking, not a carboxylic acid. In the present context it is considered equivalent to a carboxylic acid, as its reaction results in the formation of ester moieties in the (di) anhydro sugar molecule.
- ethehfication with an alcohol, such as methanol or ethanol.
- Dimethyl isosorbide and diethyl isosorbide are examples of compounds obtained by the ethehfication reaction.
- the resulting compounds are poorly soluble in the inorganic molten salt hydrate medium, allowing them to be readily separated from the medium.
- the dehvatized compounds are useful as fuel additives and/or fuel substitutes.
- Dimethyl isosorbide and diethyl isosorbide have a high cetane value, making them particularly suitable as additives in diesel fuel. Due to their oxygen content they contribute to a clean burning of the diesel fuel.
- Line 1 represents the flux of lignocellulosic biomass material.
- the lignocellulosic material (1 ) is mixed with the inorganic molten salt hydrate mixture (2) and sent together or separately to the reactor (10) to effect dissolution and, together with hydrochloric acid (3), effect the hydrolysis.
- the mixture of inorganic molten salt hydrate and sorbitol (6) is sent to the dehydration reactor (40), where at proper higher temperature conditions sorbitol is converted to isosorbide.
- the mixture of inorganic molten salt hydrate, isosorbide and hydrogen (7) is sent to a separator. Steps of heat transfer and heat recovery to the reactor feed and from the reactor product are not shown, but are well known to those skilled in the art.
- Recovered hydrogen (8) is separated from the inorganic molten salt hydrate and isosorbide mixture (9) in separator (50).
- Inorganic molten salt hydrate and isosorbide mixture (9) are sent to a separation step (60), where isosorbide and anhydro sugar alcohols (11 ) are separated from the hydrated molten salt mixture (12).
- the procedure disclosed in (60) involves contacting the inorganic molten salt hydrate and isosorbide mixture (9) with xylene or a similar hydrocarbon in a suitable contact device (62) at a temperature higher than 120 0 C.
- the apolar hydrocarbon/sorbitol phase (61 ) is separated and sent to a contact device at a low temperature (64).
- the isosorbide crystals precipitate at temperatures lower than 60 0 C.
- the temperatures, pressures, contacting times and number of contact stages at (62) and (64), together with flow of (61 ) and (63) can be selected such that all the isosorbide is removed from the inorganic molten salt hydrate.
- a regeneration of part of the inorganic molten salt hydrate might be useful, being effected at (80), from a fraction of the inorganic molten salt hydrate main flow (15), resulting in a regenerated inorganic molten salt hydrate (16), returning again to the main inorganic molten salt hydrate recycle (2).
- a small make-up (19) of inorganic molten salt hydrate may be necessary, from salt lost and recovered from lignin burning, for example.
- the inorganic molten salt hydrate in the desired composition (2) is then continuously added to the lignocellulosic material (1 ), resulting in a fully continuous process.
- saccharose such as sugarcane or sugar beet.
- saccharose would be first separated from the biomass and could be combined with biomass after hemicellulose removal and subjected to hydrolysis.
- the saccharose will hydrolyze to glucose and fructose.
- Glucose and fructose are further hydrogenated to a mixture of sorbitol and mannitol.
- Double dehydration of sorbitol and mannitol yields respectively isosorbide and isomannide (dianhydromannitol or 1 ,4:3,6-dianhydro-D-mannitol). Isomannide can be further separated the same way as the isosorbide.
- the hydrated inorganic molten salt media including the additional transition metal salt
- the additional transition metal salt being an electron acceptor - strongly interacting with the hydroxyl groups, weakening the C-O bond, and allowing intramolecular nucleophilic substitution, and thus catalyzing the internal dehydration of sorbitol molecules to the first and the second dehydration (isosorbide) products;
- EXAMPLE 1 Effect of inorganic molten salt hydrate on cellulose dissolution - comparison with cellulose stability in other solvents.
- FIG. 2 shows the HPLC results referenced to maximum glucose yield. It can be seen that at salt concentrations lower than 50 wt% no glucose was produced. Increasing the salt content increased the hydrolysis, and above 67 wt% the further increase was small. [00121] Without intending to limit the scope of the invention by any explanation, it is believed that a concentration of salt of at least 65 wt% is necessary to ensure a fast and complete dissolution. At higher salt concentrations, no additional gain was obtained.
- EXAMPLE 6 Effect of acid content on glucose hydrogenation in the hydrated inorganic molten salt media of invention.
- EXAMPLE 7 Effect of hydrated inorganic molten salt concentration on the hydrogenation step of sugar to polyol of invention.
- EXAMPLE 8 Catalytic sorbitol hydrogenolysis at higher temperature in hydrated inorganic molten salt.
- Sorbitol (0.5 g) with 0.25 g of Ru/C catalyst was mixed with 6.0 g of water or hydrated inorganic molten salt solutions of varying ZnCI 2 concentrations at 220 0 C, 50 bar and 1 h reaction time.
- water significant conversion to hydrogenolysis (isomehzation and the production of lower molar weight polyols) products is evidenced.
- the results show that the hydrated inorganic molten salt media inhibit the hydrogenolysis products and favor the formation of dehydration products, under hydrogenation conditions.
- EXAMPLE 9 Process of dehydration of sorbitol in hydrated inorganic molten salt media and effect of additional salts and comparison with dehydration in aqueous media in hydrogen and nitrogen atmosphere.
- Sorbitol (0.5 g) was mixed with 6.0 g of ZnCI 2 70 wt% or water. CuCI 2 was added in some tests as an additional salt, in a quantity of 1 mol per 2 mol of sorbitol. Temperature of reaction was 250 0 C for 1 h reaction time, and pressure 50 bar of H 2 or N 2 . HPLC results showed just 3 peaks, assigned to sorbitol, anhydrosorbitols (sorbitans) and isosorbide (1 ,4:3,6-dianhydrosorbitol).
- the hydrated inorganic molten salt is able to effect the dehydration of sorbitol - and surprisingly to a higher extent in hydrogen atmosphere instead of nitrogen atmosphere. It can be seen that the addition of additional CuCI 2 salt increased the dehydration activity. The best results were obtained with the additional salt dissolved in ZnCI 2 hydrated inorganic molten salt in hydrogen atmosphere of the present invention.
- EXAMPLE 10 Invention process of sorbitol dehydration in different hydrated inorganic molten salt medium and several additional salts.
- Sorbitol (0.5 g) was mixed with 6.0 g of different salts (ZnCI 2 70 wt% or CaCI 2 42.7 wt% or LiCI 45.4 wt%) and additional salts in a cation / sorbitol ratio of 0.1.
- Reaction pressure was 50 bar of hydrogen atmosphere and temperature of 230 0 C for 1 h time.
- the Figure shows the following product profiles, with sorbitol being dehydrated to the first dehydration product (sorbitan), followed by further dehydration of sorbitans to isosorbide.
- the main products of first dehydration are 1 ,4 and 3,6 anhydrosorbitol, and not 2,5 or 1 ,5 anhydro products - which further dehydration does not proceed according to the art.
- EXAMPLE 12 Effect of additional salt content on dehydration in inorganic molten salt hydrate.
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Abstract
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US16077009P | 2009-03-17 | 2009-03-17 | |
PCT/EP2010/053361 WO2010106055A1 (fr) | 2009-03-17 | 2010-03-16 | Procédé de transformation de polysaccharides dans un hydrate de sel fondu inorganique |
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US607091A (en) | 1898-07-12 | einar simonsen | ||
US257607A (en) | 1882-05-09 | alexander paekes | ||
US647805A (en) | 1900-01-29 | 1900-04-17 | Alexander Classen | Process of converting wood into fermentable sugars. |
US4018620A (en) | 1975-05-19 | 1977-04-19 | Biocel Corporation | Method of hydrolyzing cellulose to monosaccharides |
US4313884A (en) | 1980-01-21 | 1982-02-02 | Uop Inc. | Use of metal ions in preparation of anhydropolyols |
EP0091221B1 (fr) | 1982-04-05 | 1987-09-09 | Imperial Chemical Industries Plc | Dissolution et hydrolyse des hydrates de carbone |
US4452640A (en) | 1982-05-11 | 1984-06-05 | Purdue Research Foundation | Quantitative hydrolysis of cellulose to glucose using zinc chloride |
DE19749202C1 (de) | 1997-11-07 | 1999-05-27 | Degussa | Verfahren zur Herstellung von fünf- oder sechsgliedrigen cyclischen Ethern und Anhydrohexitgemische |
DE19841032A1 (de) | 1998-09-09 | 2000-03-16 | Aventis Res & Tech Gmbh & Co | Verfahren zur Herstellung von Anhydrozuckeralkoholen |
CN1446221A (zh) | 2000-05-26 | 2003-10-01 | 纳幕尔杜邦公司 | 借助于气体净化的脱水糖醇的制造方法 |
EP1294727A2 (fr) | 2000-05-26 | 2003-03-26 | E.I. Dupont De Nemours And Company | Procede de fabrication en continu d'alcools de sucre anhydres et reacteur utile a cet effet |
US6864378B2 (en) | 2002-04-17 | 2005-03-08 | E. I. Du Pont De Nemours And Company | Integrated continuous process for anhydro sugar alcohol manufacture |
US6831181B2 (en) | 2002-04-17 | 2004-12-14 | E. I. Dupont De Nemours And Co. | High yield byproduct recycle process for anhydro sugar alcohols |
US7772412B2 (en) | 2006-01-26 | 2010-08-10 | Battelle Memorial Institute | Methods for dehydration of sugars and sugar alcohols |
US7615652B2 (en) | 2006-01-26 | 2009-11-10 | Battelle Memorial Institute | Two-stage dehydration of sugars |
US7728156B2 (en) | 2006-01-26 | 2010-06-01 | Battelle Memorial Institute | Method of performing sugar dehydration and catalyst treatment |
US7649099B2 (en) | 2006-01-26 | 2010-01-19 | Battelle Memorial Institute | Method of forming a dianhydrosugar alcohol |
EP2100972A1 (fr) * | 2008-03-13 | 2009-09-16 | BIOeCON International Holding N.V. | Procédé pour convertir les polysaccharides dans un hydrate de sel fondu |
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