WO2011114356A1 - Low pressure hydrotreating of glycerin for production of mixed products - Google Patents

Low pressure hydrotreating of glycerin for production of mixed products Download PDF

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Publication number
WO2011114356A1
WO2011114356A1 PCT/IS2010/050011 IS2010050011W WO2011114356A1 WO 2011114356 A1 WO2011114356 A1 WO 2011114356A1 IS 2010050011 W IS2010050011 W IS 2010050011W WO 2011114356 A1 WO2011114356 A1 WO 2011114356A1
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gas
reactor
components
gas phase
product
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PCT/IS2010/050011
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French (fr)
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Gunnlaugur Fridbjarnarson
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Efnaferli Ehf.
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Publication of WO2011114356A1 publication Critical patent/WO2011114356A1/en

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    • CCHEMISTRY; METALLURGY
    • C07ORGANIC CHEMISTRY
    • C07CACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C29/00Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
    • C07C29/60Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by elimination of -OH groups, e.g. by dehydration

Definitions

  • the invention is within the field of process chemistry, more particularly involving processes of catalytic hydrogenation of glycerin and other sugar alcohols to desired polyols and other organic products, such as e.g. for the conversion of byproducts from biodiesel production to desired products.
  • WO 2005/095536 proposes a multi-step process for the hydrogenolysis of glycerin to 1,2-propylene glycol preferring using a copper-chromium catalyst and providing acetol (hydroxyacetone) as an intermediate product. Water content of feed is 50% by maximum, according to this disclosure.
  • US pat. no. 7,355,083 discloses vapor hydrogenation of vaporized glycerin at elevated temperature and pressure applying high ratio of hydrogen in relation to feed glycerin over a copper based catalyst.
  • WO 2008/071642 (BASF SE) describes the production of propylene glycol and ethylene glycol through hydrogenolysis of polyols, using palladium as active catalyst metal on various supports of among others Zr0 2 , T1O2, CaC0 3 and carbon.
  • WO 2008/133939 discloses a process for the conversion of glycerol and sorbitol into ethylene glycol, propylene glycol and 1,2-butanediol, 1,3-butanediol, 1,4-butanediol and 2,3-butanediol, using catalyst containing nickel, rhenium or a combination thereof embedded in an activated carbon matrix. Pressure applied is greater than 500 psi (3,45 MPa).
  • WO 2009/027502 (BASF SE) describes a process for the production of 1,2-propylene glycol using copper containing catalyst. Water content in feed is by maximum 20% and pressure 30- 99 bar (3-9,9 MPa).
  • the proposed reactor arrangement is a combination of two physical reactor units, one with a liquid recycle loop, the other one without.
  • the objectives of this invention relate to new and improved production pathways for producing fuel alcohols, oxo-chemicals and other intermediate chemicals such as glycols using glycerin which can be derived from biodiesel byproducts or diverse sugar alcohols as feedstock material.
  • the process of the invention operates at lower pressure than prior art processes, simplifying system requirements and startup costs substantially. Additionally, the process of the invention has low consumption of hydrogen compared to comparable prior art hydrogenation processes. Hydrogen generally has to be provided as an external supply and cannot be harvested from natural sources. This further reduces operation costs. Applying process conditions as described herein, catalysts and operational parameters, surprisingly high selectivity towards alcohols and oxo-chemicals other than glycols could be achieved. Alcohols and oxo-chemicals achieved by this method are highly suited as renewable octane booster additives in gasoline fuel blends.
  • the invention sets forth a process for reacting a reactant feedstock that comprises glycerol, other sugar alcohols or any mixture thereof with hydrogen, for obtaining a product mixture comprising as major product components propylene glycol and ethylene glycol and one or more minor product components which can be a C1-C3 alcohol, acetone, hydroxy- acetone or any mixture thereof.
  • the process comprises feeding to a reactor which is suitably a fixed bed reactor charged with solid catalyst a reagent mix comprising said reactant feedstock, a solvent, and hydrogen gas.
  • the reactor operates at a pressure in the range of about 1.0 to about 12.0 MPa, such as in the range of about 1-10 MPa, in particular between about 2 and about 10 MPa, such as more preferably in the range of about 2-6 MPa or in the range of about 1-4 MPa.
  • pressure values higher than atmospheric pressure indicate gauge pressure, i.e. pressure values referenced against ambient air pressure.
  • an advantage of the invention is that the molar ratio of the feed hydrogen gas to said reactant feedstock is below 1 : 1, preferably below about 1 : 1.2, such as below about 1 : 1.5 (2: 3) or below about 3 :5 (1 : 1.67) and more preferably lower than 1 :2 or more preferably below about 1 : 3.
  • Another indicator of hydrogen consumption is hydrogen fed into the system relative to the reactant feedstock which is actually converted.
  • the molar ratio of the feed hydrogen to the reactant feedstock which is consumed is below about 1 : 1, such as in the range of about 1 : 2 to about 1 : 1, preferably below about 1 : 1.2 and more preferably below about 1 : 1.5 or below about 1 : 1.67 and in certain embodiments below about 1 :2.
  • Figure 1 Schematic illustration of a system according to the invention with a water cleaning unit for purifying gaseous product components.
  • Figure 2 Schematic illustration of a system according to the invention, as described further in the detailed description as "Alternative process with secondary reactor”.
  • Figure 3 Illustration of one embodiment of the secondary reactor in a system as described in Fig. 2.
  • Glycerin is used herein interchangeably with the term glycerol, the IUPAC term for the compound is propane-l,2,3-triol.
  • the process in this invention provides a single step continuous flow operation process for the conversion of feedstock solution of sugar alcohols into other oxygen containing compounds with a lower molecular weight than the feedstock material.
  • Biodiesel refers to a vegetable or algae oil or animal fat-derived diesel fuel consisting of long chain alkyl esters.
  • Biodiesel can be produced from waste vegetable oil (e.g . used frying oil) and animal fat but virgin vegetable oil is predominantly used.
  • the oils contain triglycerides which are reacted which alcohol (typically ethanol or methanol) under catalytic conditions, converting the triglycerides to ethyl esters of the fatty acids of the triglycerides, while the glyceride backbone is left as glycerol.
  • Other byproducts are soap and excess alcohol . Consequently, with increased biodiesel production, large amounts of glycerol are generated that must be disposed of or used in a practical way.
  • biodiesel production from vegetable oil about
  • the glycerol produced from transesterification biodiesel production is readily separated from the biodiesel long chain esters, as the density of glycerol is greater than that of the biodiesel chains.
  • Preferably such crude glycerol feedstock is refined by short path distillation to remove contaminants such as sulfuric acid.
  • the process of the present invention is, however, also suitable for other related feedstock material, such as but not limited to sugar alcohols, or a mixture of glycerol and sugar alcohols.
  • sugar alcohols which can be treated include but are not limited to sorbitol, mannitol, arabinitol, xylitol, erythritol, maltitol, and lactitol and any combinations thereof and also including combinations of one or more of such sugar alcohols and glycerol.
  • Sorbitol can be obtained from hydrogenation of glucose from starch.
  • a suitable polyol feedstock is obtained as mixed polyols.
  • Natural fibers can be hydrolyzed (producing a hydrolysate) to provide a bio-derived polyol feedstock, such as mixtures of polyols.
  • Fibers suitable for this purpose include, but are not limited to, corn fiber from corn wet mills, dry corn gluten feed which contains corn fiber from dry mills, wet corn gluten feed from wet corn mills that do not run dryers, distiller dry grains solubles (DDGS) and Distiller's Grain Solubles (DGS) from dry corn mills, canola hulls, rapeseed hulls, peanut shells, soybean hulls, cottonseed hulls, cocoa hulls, barley hulls, oat hulls, wheat straw, corn stover, rice hulls, starch streams from wheat processing, fiber streams from corn masa plants, edible bean molasses, edible bean fiber, and mixtures of any thereof.
  • DDGS distiller dry grains soluble
  • Hydrolysates of natural fibers may be enriched in bio-derived polyol feedstock suitable for use as a feedstock in the hydrogenation reaction described herein, including, but not limited to, arabinose, xylose, sucrose, maltose, isomaltose, fructose, mannose, galactose, glucose, and mixtures of any thereof.
  • the obtained propylene glycol and ethylene glycol are referred to as major products.
  • the amount of minor products which term is defined as the products other than propylene glycol and ethylene glycol, which can be but are not limited to C1-C3 alcohols, acetone and hydroxy-acetone, can be controlled so as to obtain a relatively high content of minor products, as compared to prior art procedures.
  • the minor products comprise at least 2 wt% of the total combined obtained amount of the major and minor components, and more preferably at least 3 wt% and yet more preferably at least about 4 wt% or at least about 5 wt%.
  • an even higher fraction of said minor products constitute a higher fraction, such as above about 10%, and more preferably above about 15%, such as in the range of about 5-25%, including the range of about 10-25%, such as in the range of about 5-20%.
  • Further minor products produced with the invention may include one or more of methanol, ethanol, 2-propanol, lactic acid, sodium lactate, glyceric acid, sodium glycerate, and also C4 compounds including but not limited to butanediols including 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, and 2,3-butanediol, and C5 compounds including 2-4-pentanediol.
  • the solvent fed with the reactant feedstock to the reactor is preferably water or an aqueous solution or mixture of water and other solvent.
  • Other solvents are as well usable, such as an alcohol or mixture of alcohols.
  • the solvent can advantageously be used in a relative amount of 1 :4 or higher, e.g . in the range of 20% solvent to 60% solvent, against the liquid reactant feedstock, such as e.g. more than 1 : 1 or more than 2: 1 (referring to more than 50% water and more than 66% water, respectively, of the total stream fed to the reactor) and more preferably more than 3 : 1 (more than 75% water).
  • even more solvent is applied to the stream such that the reactant feedstock is in a concentration in the range of about 5-20%, such as about 5-10%, or in the range of 10-20%, e.g . about 10%, about 15% or about 20%.
  • concentration in the range of about 5-20%, such as about 5-10%, or in the range of 10-20%, e.g . about 10%, about 15% or about 20%.
  • the exact configuration as to the relative amount of solvent used may depend on several factors, such as access to water, cost of energy needed for separation/drying at any given location, etc.
  • the reagent mix will in certain embodiments also include a co-catalyst which may be an alkali metal hydroxide, which can be added to the reactant stream before or after mixing with hydrogen or a combination of both.
  • a co-catalyst which may be an alkali metal hydroxide, which can be added to the reactant stream before or after mixing with hydrogen or a combination of both.
  • the concentration of co-catalyst may be within the range of about 0-2%, in particular in the range of about 0,1-0.6 % w/v.
  • the alkali promoter can be but is not limited to one or more from NaOH, CaOH, NH 4 OH or NaC0 3 , preferably NaOH.
  • a solid base catalyst can be used and then it is homogeneously mixed within the catalyst bed.
  • the components of the reagent mix can be mixed together all in one mixing unit, i.e. the reactant feedstock, solvent, hydrogen and optional co-catalyst, or the reactant feedstock and solvent are mixed and the optional co-catalyst, and hydrogen added separately to the reagent mix.
  • This educt stream is transferred to the reactor.
  • the pressure of the stream is suitably elevated after the stream leaves the mixing unit to a suitable pressure for the reaction chamber.
  • the pressure in the reactor is within the ragne mentioned above.
  • the operating termperature in the reactor is suitably in the range between about 100-250°C, such as preferably in range of about 160 to 250°C, and more preferably in the range of about 160-200°C, including about 170°C, about 180°C, about 185°C, about 190°C, about 200°C, about 225°C and about 250°C.
  • the reactor in the invention operates at a pressure below about 3.45 MPa and a tempearture below about 210°C.
  • the catalyst can be selected from one of several known and commercially available catalysts, known to the skilled person.
  • the catalyst may suitably comprise a transition metal selected from one or more of palladium, platinum, ruthenium, chromium, nickel, copper, iron, zinc, rhodium, cobalt, mangan and molybdenum, and any combinations thereof, including but not limited to Ni/Re, Cu/Re, and Co/Re.
  • the catalyst transition metal is deposited on an inert support matrix, such as carbon, Al 2 0 3 , Si0 2 , Zr0 2 , Ti0 2 , CaC0 3 , SiC, MgO, or a mixture thereof.
  • an inert support matrix such as carbon, Al 2 0 3 , Si0 2 , Zr0 2 , Ti0 2 , CaC0 3 , SiC, MgO, or a mixture thereof.
  • the form of the catalyst can vary from being powder, granulate, extrudates, pellets or a combination thereof.
  • the reactor used in the process of the invention is preferably a fixed bed catalytic reactor.
  • the solid catalyst pellets are held in place and do not move with respect to an outer reference (i.e. the external reactor container).
  • the reactor is configured with trickle bed catalyst arrangement.
  • the reactor may also consist of more than one physical body connected in series, such as two, three or four reactor chambers.
  • a useful embodiment of the invention provides for including in the process feeding at least one of the reactant components and preferably all the reagent mix of through a two-way recuperator which receives as a counter stream the product stream from the reactor.
  • a two-way recuperator which receives as a counter stream the product stream from the reactor.
  • the product stream coming from the reactor and after passing through the optional recuperator, is preferably transferred through a further cooler unit, from there the product stream is suitably separated by a gas/liquid separating unit in a gas phase stream and a liquid stream, comprising the major product components and the minor product components.
  • these components are further separated in a product separation unit, such as indicated in the embodiment illustrated in Figure 1.
  • This product separation unit can be a distillation unit.
  • the gas stream from said gas/liquid is in one embodiment led trough a purification unit, wherein the gas stream is brought in contact with water, for removal of undesired species.
  • a purification unit wherein the gas stream is brought in contact with water, for removal of undesired species.
  • One version of this is shown schematically in Fig . 1, (see item 7).
  • carbon dioxide can be substantially removed from the gas stream .
  • the remaining purified gas stream or a portion thereof can be recycled and mixed with the reactant stream to enter the reactor. It should suitably be re-pressurised prior to such recycling.
  • gaseous byproducts are not recycled or to a less extent, but rather processed further in a secondary reactor.
  • a secondary reactor Such embodiment is exemplified in Figure 2.
  • the gas stream received from the gas/liquid separator is compressed in a compressor. Additional hydrogen may be added, depending on the composition of the gas stream and the intended further use.
  • the compressed gas mixture is heated to a suitable temperature and fed to a secondary reaction unit.
  • This secondary reaction unit is filled with a solid catalyst in order to convert these non-condensed gases to components including methanol or methane, in particular methanol.
  • Such processes for converting C02 to methane or methanol are well known in the art, see e.g. Koeppel E.A. et al., Appl.
  • catalysts include but are not limited to Cu/ZnO/AI 2 0 3 , Cu/Zr0 2 or CU-Zn-Cr based catalysts or any other catalyst suitable for the conversion of carbon dioxide.
  • the product stream from the secondary reactor is preferably directed to a gas/liquid separator which can be a combined cooler-gas/liquid separator, where condensed products are separated in a liquid phase.
  • the gas phase from the gas/liquid separator can optionally be recycled back to the secondary reactor or the primary reactor, the gas phase product stream may also be transferred to a gas separation device where gas components can be separated, such as with a molecular sieve (e.g. of zeolite type) or a gas semi-permeable polymer membrane separation device.
  • a gas product stream can be obtained which is enriched in methane.
  • This product stream can be utilised in many ways, e.g.
  • a lean stream is separated from the methane- enriched stream, this lean stream includes inorganic components (hydrogen and carbon dioxide) and is suitably recycled back to the secondary reactor.
  • Methane gas coming from this process benefits in that the carbon originates from non-fossil resources, and thus is priced and/or taxed in many countries differently from conventional fossil source natural gas.
  • thermal energy is used for heating and/or product separation (including in particular distillation steps).
  • ion exchange or membrane separating devices are not needed and are not used in certain embodiments.
  • the thermal energy may comprise or be exclusively geothermal energy.
  • an educts solution containing feedstock materials as described above, is conveyed in a pipeline P-110 into a mixing unit 1 where it is conditioned with a solvent and optionally mixed with an alkaline co-catalyst solution through a separate line, P-120.
  • the mixing unit 1 which may optionally be combined with a mixing buffer, the feed solution is brought to elevated pressure.
  • Preferred solvent is water.
  • Typical hourly space velocity (LHSV) of liquid reactor feed is in the range from about 0,2 to about 5 m 3 -feed/m 3 -catalyst per hour.
  • Hydrogen from a provided source is fed into the solution through line P-130 and mixed into the fluid in line P-140 and the resulting fluid, which is conveyed in a two phase flow through a recuperative device 2 where simultaneously a partial heating of the educts solution and a cooling of the reactor 4 product solution is realized, and from there to a cooler 5 where the reactor product temperature is adjusted .
  • Recuperator device 2 is an important part of this embodiment of the reactor system, it may either be entered with single or two phase flow fluids. Its purpose is to improve the thermal efficiency of the process and reduce the operation and capital cost of the system.
  • the reactor 4 is configured with so called trickle catalyst arrangement where two phases are fed in at the top and distributed evenly over a solid catalyst configured in a fixed bed internally supported within the reactor body.
  • the reactor consists of more than one physical body connected in series, with or without intermediate heating or cooling devices.
  • the concentration of feed solution may in this embodiment vary within the range of 5-80% w/v and the system pressure within the range of about 1-12 MPa, in particular between 2 and 10 MPa, such as more preferably in the range of about 2-6 MPa.
  • the temperature in the reactor system 4 may vary within the range of 100-250°C, in particular in the range of 160 to 250°C.
  • the hydrogen consumption in this embodiment is characterized as follows: Molar ratio makeup hydrogen to feed glycerin in a steady state operation is less than 1 : 1.
  • recuperative device 2 Reactor products leaving recuperative device 2 are now led to an additional cooler 5 and from there in a gas/liquid separator 6 that is operated at the system pressure.
  • the gaseous stream from device 6 is treated separately in a special unit 7 where it is brought in direct contact with water in order to remove impurities from the gaseous effluent stream .
  • Purified gaseous effluent stream prior to entering discharging line P-200 is partially recycled to the system after elevating its pressure by a gas compression device 8.
  • the remaining fraction of the purified effluent gas stream is discharged through line P-200. It can individually be traded or used for different purposes within the process.
  • the liquid escaping gas/liquid separator is now pressure released and led into an evaporator and distilling device 9 where solvent and alcohol rich fraction are removed and separated from the higher boiling liquid components. This operation can be done by means of conventional evaporation, distillation or rectification methods. The solvent is recycled to the feed blend section through line P-170.
  • the liquid product fluid enters a separate pressure releasing device prior entering the evaporation and distillation section.
  • This may include another gas/liquid separator whereby additional fraction of dissolved gases can be recovered from the liquid stream and brought up to the system pressure and recycled .
  • Higher boiling and solvent free fraction from device 9, containing among others ethylene glycol, propylene glycol and unreacted feedstock material now enters a product separation device 10 where ethylene glycol and propylene glycol are individually separated and purified, leaving a heavier boiling fraction to be recycled (line P-160) and a smaller fraction there from to be purged.
  • Suitable equipments for this operation are flash, falling or wiped film evaporators followed by one or more fractionation devices equipped with structural packing or sieve trays, thus realizing the necessary and suited quantities of effective separation steps.
  • Alternative process option is related to the special managing and treatment of gaseous byproducts.
  • the perspectives taking into consideration a process scheme according to Fig . 2.
  • the compressor 7 may also optionally be served with additional hydrogen from main hydrogen feed line P-130, in order to balance the gas mixture in a desired way.
  • the compressed gas mixture is tempered and led into a separate gas phase reactor 8, filled with a solid catalyst, where the gaseous components partially undertake chemical reaction.
  • the desired reactor products are low boiling oxo-chemicals, especially methanol, thus providing an alternative route for the production of bio-methanol.
  • Gases escaping reactor 8 are led to a combined cooler-gas/liquid separator 9 where condensed reactor products are separated in a liquid phase.
  • the gases escaping the gas/liquid separator are tempered and pressure balanced in order to treat them in a gas separation device 10.
  • Gas phase reactor system 8 according alternative process arrangement, Fig. 2, can have a special configuration as shown by Fig. 3.
  • the gaseous feed components are first led through a recuperative device 8a prior tempered to the desired entering temperature in a feed heater 8b.
  • the gases stream vertically upwards, or optionally downward, through a solid catalyst bed reactor 8c where chemical reactions between the feed gas components take place.
  • the reactor is operated adiabatically.
  • the gaseous reactor product gases are then partially cooled in recuperative device 8a, where product components may start condensing .
  • the reactor product fluid escaping recuperator are then led to a separate cooler/condenser 9 (Fig 2.) for condensation and separation of reactor products.
  • GHSV hourly space velocity
  • Example 7 Products from Example 7 were put into a simple laboratory still with a rectification device.
  • the alcohols were concentrated by multiple batch distillation (atmospheric) by the separation of approx. 10 % overhead product ratio each time.
  • the first overhead product contained 25-30 % w/v alcohol mixture. Second distillation of the first overhead product enabled the concentration of alcohols and oxo-chemicals with lower molecular weight than glycerin of over 93 % v/v.
  • Example 9 Example 9:
  • Residues from Example 8 were run through vacuum distillation in Rotavap equipment. Pressure was kept 10 mbar a s and temperature 130°C. Evaporated material was condensed and collected . Overhead products contained propylene glycol, ethylene glycol, and some hydroxyacetone. Only traces of glycerol were noticed.
  • Example 11 Gaseous effluent stream escaping reactor system in Example 2 containing impurities was led through a water column under system pressure. Some of the impurities are dissolving in water. Gas escaping the washing device showed hydrogen to methane molar ratio lower than 1 :2. Other impurities were lower than 2 % v/v in concentration.
  • Example 11 Example 11 :
  • Gaseous stream reflecting an effluent process stream from compressor 7 in figure 2, is brought to an elevated pressure and temperature of approximately 6 MPa and 240°C respectively and passed through a fixed catalyst bed reactor containing CuO and ZnO.
  • Gaseous stream, reflecting an effluent process stream from operation step 9 in figure 2, containing methane, hydrogen, water and carbon dioxide is passed through a hollow fiber gas membrane module.
  • Water gas, hydrogen and carbon dioxide passes easily through the membrane wall, reflecting a process stream of P-190, also called a permeate, showing enriched concentration of those components compared with the feed gas mixture.
  • the rejected stream, P-200 called a retentate, contains enriched concentration of methane, CH 4 , beside a lean concentration of water gas, hydrogen and carbon dioxide.

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Abstract

The objectives of this invention relate to new and improved production pathways for producing fuel alcohols, oxo-chemicals and other intermediate chemicals such as glycols using glycerin which can be derived from biodiesel byproducts or diverse sugar alcohols as feedstock material. The process of the invention operates at lower pressure than most prior art processes, simplifying system requirements and startup costs substantially. Additionally, the process of the invention has low consumption of hydrogen compared to comparable prior art hydrogenation processes.

Description

Low pressure hydrotreating of glycerin for production of mixed products
FIELD OF INVENTION
The invention is within the field of process chemistry, more particularly involving processes of catalytic hydrogenation of glycerin and other sugar alcohols to desired polyols and other organic products, such as e.g. for the conversion of byproducts from biodiesel production to desired products.
TECHNICAL BACKGROUND
Many developers have been seeking improved solutions for converting bio-based feedstocks into chemicals of higher value. Different routes for producing intermediate chemicals and fuels from biomaterial have gained interest and can be achieved over various agricultural and renewable raw material feed sources. Rising petrochemical prices and diminishing natural stocks favor economical perspectives for such technologies as does increased awareness about the global impact of fossil fuel combustion on climate. Therefore, the importance of developing sustainable technologies using bio-materials is increasing .
A number of patent documents have been published in the field of glycerin hydrogenolysis and glycerin conversion. Various proposals of heterogeneous pathways for glycerin conversion can be found, of which the following are representative disclosures: WO 2009/027502, US
2009/0105509, WO 2008/133939, WO 2008/051540, WO 2008/071642, US 7,355,083, WO 2005/095536, and US 5,276, 181. The conventional processes for hydrogenolysis of sugar alcohols involve high temperature and high pressure reaction conditions.
US patent No. 5,276,181 (Montecatini Tech. S.r.l.) discloses examples of hydrogenolysis of glycerin towards high yield of propylene glycol using ruthenium on carbon support.
WO 2005/095536 (Suppes et. al .) proposes a multi-step process for the hydrogenolysis of glycerin to 1,2-propylene glycol preferring using a copper-chromium catalyst and providing acetol (hydroxyacetone) as an intermediate product. Water content of feed is 50% by maximum, according to this disclosure.
US pat. no. 7,355,083 (Davy Process Technology Limited) discloses vapor hydrogenation of vaporized glycerin at elevated temperature and pressure applying high ratio of hydrogen in relation to feed glycerin over a copper based catalyst.
WO 2008/071642 (BASF SE) describes the production of propylene glycol and ethylene glycol through hydrogenolysis of polyols, using palladium as active catalyst metal on various supports of among others Zr02, T1O2, CaC03 and carbon.
WO 2008/133939 (Archer-Daniels-Midland Company) discloses a process for the conversion of glycerol and sorbitol into ethylene glycol, propylene glycol and 1,2-butanediol, 1,3-butanediol, 1,4-butanediol and 2,3-butanediol, using catalyst containing nickel, rhenium or a combination thereof embedded in an activated carbon matrix. Pressure applied is greater than 500 psi (3,45 MPa).
US 2009/0105509 (Galen J. Suppes) discloses a process for converting glycerol to acetol and then acetol to propylene glycol with low amounts of ethylene glycol produced.
WO 2009/027502 (BASF SE) describes a process for the production of 1,2-propylene glycol using copper containing catalyst. Water content in feed is by maximum 20% and pressure 30- 99 bar (3-9,9 MPa). The proposed reactor arrangement is a combination of two physical reactor units, one with a liquid recycle loop, the other one without.
New and improved methods for increasing value of side products from biomaterial-based fuel would be much appreciated.
SUMMARY OF INVENTION
The objectives of this invention relate to new and improved production pathways for producing fuel alcohols, oxo-chemicals and other intermediate chemicals such as glycols using glycerin which can be derived from biodiesel byproducts or diverse sugar alcohols as feedstock material. The process of the invention operates at lower pressure than prior art processes, simplifying system requirements and startup costs substantially. Additionally, the process of the invention has low consumption of hydrogen compared to comparable prior art hydrogenation processes. Hydrogen generally has to be provided as an external supply and cannot be harvested from natural sources. This further reduces operation costs. Applying process conditions as described herein, catalysts and operational parameters, surprisingly high selectivity towards alcohols and oxo-chemicals other than glycols could be achieved. Alcohols and oxo-chemicals achieved by this method are highly suited as renewable octane booster additives in gasoline fuel blends.
In a first aspect, the invention sets forth a process for reacting a reactant feedstock that comprises glycerol, other sugar alcohols or any mixture thereof with hydrogen, for obtaining a product mixture comprising as major product components propylene glycol and ethylene glycol and one or more minor product components which can be a C1-C3 alcohol, acetone, hydroxy- acetone or any mixture thereof. The process comprises feeding to a reactor which is suitably a fixed bed reactor charged with solid catalyst a reagent mix comprising said reactant feedstock, a solvent, and hydrogen gas.
The reactor operates at a pressure in the range of about 1.0 to about 12.0 MPa, such as in the range of about 1-10 MPa, in particular between about 2 and about 10 MPa, such as more preferably in the range of about 2-6 MPa or in the range of about 1-4 MPa. In this context, if not otherwise indicated pressure values higher than atmospheric pressure indicate gauge pressure, i.e. pressure values referenced against ambient air pressure.
As mentioned, an advantage of the invention is that the molar ratio of the feed hydrogen gas to said reactant feedstock is below 1 : 1, preferably below about 1 : 1.2, such as below about 1 : 1.5 (2: 3) or below about 3 :5 (1 : 1.67) and more preferably lower than 1 :2 or more preferably below about 1 : 3. This means that the overall hydrogen consumption is relatively low and indeed lower that in more conventional prior art hydrogenation processes mentioned above.
Another indicator of hydrogen consumption is hydrogen fed into the system relative to the reactant feedstock which is actually converted. Preferably the molar ratio of the feed hydrogen to the reactant feedstock which is consumed is below about 1 : 1, such as in the range of about 1 : 2 to about 1 : 1, preferably below about 1 : 1.2 and more preferably below about 1 : 1.5 or below about 1 : 1.67 and in certain embodiments below about 1 :2.
BRIEF DESCRIPTION OF FIGURES
Figure 1 : Schematic illustration of a system according to the invention with a water cleaning unit for purifying gaseous product components.
Figure 2 : Schematic illustration of a system according to the invention, as described further in the detailed description as "Alternative process with secondary reactor".
Figure 3 : Illustration of one embodiment of the secondary reactor in a system as described in Fig. 2.
DETAILED DESCRIPTION
Glycerin is used herein interchangeably with the term glycerol, the IUPAC term for the compound is propane-l,2,3-triol.
The process in this invention provides a single step continuous flow operation process for the conversion of feedstock solution of sugar alcohols into other oxygen containing compounds with a lower molecular weight than the feedstock material.
As mentioned above, the process of the invention is suitable for treating a feedstock such as biodiesel byproducts. Biodiesel refers to a vegetable or algae oil or animal fat-derived diesel fuel consisting of long chain alkyl esters. Biodiesel can be produced from waste vegetable oil (e.g . used frying oil) and animal fat but virgin vegetable oil is predominantly used. The oils contain triglycerides which are reacted which alcohol (typically ethanol or methanol) under catalytic conditions, converting the triglycerides to ethyl esters of the fatty acids of the triglycerides, while the glyceride backbone is left as glycerol. Other byproducts are soap and excess alcohol . Consequently, with increased biodiesel production, large amounts of glycerol are generated that must be disposed of or used in a practical way. In biodiesel production from vegetable oil, about
1 kg of crude glycerol is obtained for every 9 kg of biodiesel. This is why economical and commercially viable processes making use of the glycerol byproduct are in demand.
The glycerol produced from transesterification biodiesel production is readily separated from the biodiesel long chain esters, as the density of glycerol is greater than that of the biodiesel chains. Preferably such crude glycerol feedstock is refined by short path distillation to remove contaminants such as sulfuric acid.
The process of the present invention is, however, also suitable for other related feedstock material, such as but not limited to sugar alcohols, or a mixture of glycerol and sugar alcohols. Such sugar alcohols which can be treated include but are not limited to sorbitol, mannitol, arabinitol, xylitol, erythritol, maltitol, and lactitol and any combinations thereof and also including combinations of one or more of such sugar alcohols and glycerol. Sorbitol can be obtained from hydrogenation of glucose from starch.
In other embodiments, a suitable polyol feedstock is obtained as mixed polyols. Natural fibers can be hydrolyzed (producing a hydrolysate) to provide a bio-derived polyol feedstock, such as mixtures of polyols. Fibers suitable for this purpose include, but are not limited to, corn fiber from corn wet mills, dry corn gluten feed which contains corn fiber from dry mills, wet corn gluten feed from wet corn mills that do not run dryers, distiller dry grains solubles (DDGS) and Distiller's Grain Solubles (DGS) from dry corn mills, canola hulls, rapeseed hulls, peanut shells, soybean hulls, cottonseed hulls, cocoa hulls, barley hulls, oat hulls, wheat straw, corn stover, rice hulls, starch streams from wheat processing, fiber streams from corn masa plants, edible bean molasses, edible bean fiber, and mixtures of any thereof. Hydrolysates of natural fibers, such as corn fiber, may be enriched in bio-derived polyol feedstock suitable for use as a feedstock in the hydrogenation reaction described herein, including, but not limited to, arabinose, xylose, sucrose, maltose, isomaltose, fructose, mannose, galactose, glucose, and mixtures of any thereof.
In this description, the obtained propylene glycol and ethylene glycol are referred to as major products. It is an advantage of the invention that the amount of minor products, which term is defined as the products other than propylene glycol and ethylene glycol, which can be but are not limited to C1-C3 alcohols, acetone and hydroxy-acetone, can be controlled so as to obtain a relatively high content of minor products, as compared to prior art procedures. In preferred embodiments of the invention, the minor products comprise at least 2 wt% of the total combined obtained amount of the major and minor components, and more preferably at least 3 wt% and yet more preferably at least about 4 wt% or at least about 5 wt%. The percentages herein refer to wt/wt percentages unless otherwise stated. In some embodiments an even higher fraction of said minor products constitute a higher fraction, such as above about 10%, and more preferably above about 15%, such as in the range of about 5-25%, including the range of about 10-25%, such as in the range of about 5-20%.
Further minor products produced with the invention may include one or more of methanol, ethanol, 2-propanol, lactic acid, sodium lactate, glyceric acid, sodium glycerate, and also C4 compounds including but not limited to butanediols including 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, and 2,3-butanediol, and C5 compounds including 2-4-pentanediol.
The solvent fed with the reactant feedstock to the reactor is preferably water or an aqueous solution or mixture of water and other solvent. Other solvents are as well usable, such as an alcohol or mixture of alcohols. The solvent can advantageously be used in a relative amount of 1 :4 or higher, e.g . in the range of 20% solvent to 60% solvent, against the liquid reactant feedstock, such as e.g. more than 1 : 1 or more than 2: 1 (referring to more than 50% water and more than 66% water, respectively, of the total stream fed to the reactor) and more preferably more than 3 : 1 (more than 75% water). In some embodiments even more solvent is applied to the stream such that the reactant feedstock is in a concentration in the range of about 5-20%, such as about 5-10%, or in the range of 10-20%, e.g . about 10%, about 15% or about 20%. The exact configuration as to the relative amount of solvent used may depend on several factors, such as access to water, cost of energy needed for separation/drying at any given location, etc.
The reagent mix will in certain embodiments also include a co-catalyst which may be an alkali metal hydroxide, which can be added to the reactant stream before or after mixing with hydrogen or a combination of both. The concentration of co-catalyst may be within the range of about 0-2%, in particular in the range of about 0,1-0.6 % w/v. The alkali promoter can be but is not limited to one or more from NaOH, CaOH, NH4OH or NaC03, preferably NaOH. Optionally a solid base catalyst can be used and then it is homogeneously mixed within the catalyst bed.
The components of the reagent mix can be mixed together all in one mixing unit, i.e. the reactant feedstock, solvent, hydrogen and optional co-catalyst, or the reactant feedstock and solvent are mixed and the optional co-catalyst, and hydrogen added separately to the reagent mix. This educt stream is transferred to the reactor. The pressure of the stream is suitably elevated after the stream leaves the mixing unit to a suitable pressure for the reaction chamber.
The pressure in the reactor is within the ragne mentioned above. The operating termperature in the reactor is suitably in the range between about 100-250°C, such as preferably in range of about 160 to 250°C, and more preferably in the range of about 160-200°C, including about 170°C, about 180°C, about 185°C, about 190°C, about 200°C, about 225°C and about 250°C.
In one embodiment, the reactor in the invention operates at a pressure below about 3.45 MPa and a tempearture below about 210°C.
The catalyst can be selected from one of several known and commercially available catalysts, known to the skilled person. The catalyst may suitably comprise a transition metal selected from one or more of palladium, platinum, ruthenium, chromium, nickel, copper, iron, zinc, rhodium, cobalt, mangan and molybdenum, and any combinations thereof, including but not limited to Ni/Re, Cu/Re, and Co/Re.
In some embodiments, the catalyst transition metal is deposited on an inert support matrix, such as carbon, Al203, Si02, Zr02, Ti02, CaC03, SiC, MgO, or a mixture thereof. The form of the catalyst can vary from being powder, granulate, extrudates, pellets or a combination thereof.
The reactor used in the process of the invention is preferably a fixed bed catalytic reactor. In such fixed bed reactor, the solid catalyst pellets are held in place and do not move with respect to an outer reference (i.e. the external reactor container). Preferably, the reactor is configured with trickle bed catalyst arrangement. The reactor may also consist of more than one physical body connected in series, such as two, three or four reactor chambers.
A useful embodiment of the invention provides for including in the process feeding at least one of the reactant components and preferably all the reagent mix of through a two-way recuperator which receives as a counter stream the product stream from the reactor. Thus the heat from the product stream is transferred and utilised to heat the respective at least one reactant component and the product stream is thereby cooled . This increases the overall efficiency of the system, as the reactants should have a desired temperature in the reaction chamber, and the product stream should be cooled down for effective separation of gas and liquid species.
The product stream coming from the reactor and after passing through the optional recuperator, is preferably transferred through a further cooler unit, from there the product stream is suitably separated by a gas/liquid separating unit in a gas phase stream and a liquid stream, comprising the major product components and the minor product components. Also, in useful
embodiments, these components are further separated in a product separation unit, such as indicated in the embodiment illustrated in Figure 1. This product separation unit can be a distillation unit.
The gas stream from said gas/liquid is in one embodiment led trough a purification unit, wherein the gas stream is brought in contact with water, for removal of undesired species. One version of this is shown schematically in Fig . 1, (see item 7). With this arrangement carbon dioxide can be substantially removed from the gas stream . The remaining purified gas stream or a portion thereof can be recycled and mixed with the reactant stream to enter the reactor. It should suitably be re-pressurised prior to such recycling.
In a different embodiment, gaseous byproducts are not recycled or to a less extent, but rather processed further in a secondary reactor. Such embodiment is exemplified in Figure 2. The gas stream received from the gas/liquid separator is compressed in a compressor. Additional hydrogen may be added, depending on the composition of the gas stream and the intended further use. The compressed gas mixture is heated to a suitable temperature and fed to a secondary reaction unit. This secondary reaction unit is filled with a solid catalyst in order to convert these non-condensed gases to components including methanol or methane, in particular methanol. Such processes for converting C02 to methane or methanol are well known in the art, see e.g. Koeppel E.A. et al., Appl. catalysis A (1992) 84, 77-102; Klier, K. "Methanol Synthesis" in Advances in Catalysis Vol. 31, 243-310, ed. Eley, Pines, Weisz, Academic Press, UK, 1982. Processes for direct conversion of C02 are also possible. For the secondary reactor useful catalysts include but are not limited to Cu/ZnO/AI203, Cu/Zr02 or CU-Zn-Cr based catalysts or any other catalyst suitable for the conversion of carbon dioxide.
The product stream from the secondary reactor is preferably directed to a gas/liquid separator which can be a combined cooler-gas/liquid separator, where condensed products are separated in a liquid phase. The gas phase from the gas/liquid separator can optionally be recycled back to the secondary reactor or the primary reactor, the gas phase product stream may also be transferred to a gas separation device where gas components can be separated, such as with a molecular sieve (e.g. of zeolite type) or a gas semi-permeable polymer membrane separation device. Thus, a gas product stream can be obtained which is enriched in methane. This product stream can be utilised in many ways, e.g. as feedstock for hydrogen production (reacting with water in high temperature steam reforming), for combustion, compressed for use as automotive fuel, or distributed to a gas distribution network. A lean stream is separated from the methane- enriched stream, this lean stream includes inorganic components (hydrogen and carbon dioxide) and is suitably recycled back to the secondary reactor.
Methane gas coming from this process benefits in that the carbon originates from non-fossil resources, and thus is priced and/or taxed in many countries differently from conventional fossil source natural gas.
In some embodiments of the invention thermal energy is used for heating and/or product separation (including in particular distillation steps). In these embodiments ion exchange or membrane separating devices are not needed and are not used in certain embodiments.
Depending on the location of the plant, the thermal energy may comprise or be exclusively geothermal energy.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
The following abbreviation legends are used in the figures:
Ale: alcohols/light boiling
CW: cooling water
CWR: cooling water return
Prg. : Purge stream
Prd.: Product component
PS: Process solvent
PSR: Process solvent return
PW: process water
PWR: process water return
As seen in Fig. 1, an educts solution, containing feedstock materials as described above, is conveyed in a pipeline P-110 into a mixing unit 1 where it is conditioned with a solvent and optionally mixed with an alkaline co-catalyst solution through a separate line, P-120. From the mixing unit 1, which may optionally be combined with a mixing buffer, the feed solution is brought to elevated pressure. Preferred solvent is water. Typical hourly space velocity (LHSV) of liquid reactor feed is in the range from about 0,2 to about 5 m3-feed/m3-catalyst per hour. Hydrogen from a provided source is fed into the solution through line P-130 and mixed into the fluid in line P-140 and the resulting fluid, which is conveyed in a two phase flow through a recuperative device 2 where simultaneously a partial heating of the educts solution and a cooling of the reactor 4 product solution is realized, and from there to a cooler 5 where the reactor product temperature is adjusted .
Recuperator device 2 is an important part of this embodiment of the reactor system, it may either be entered with single or two phase flow fluids. Its purpose is to improve the thermal efficiency of the process and reduce the operation and capital cost of the system.
The reactor 4 is configured with so called trickle catalyst arrangement where two phases are fed in at the top and distributed evenly over a solid catalyst configured in a fixed bed internally supported within the reactor body. Optionally, the reactor consists of more than one physical body connected in series, with or without intermediate heating or cooling devices.
The concentration of feed solution may in this embodiment vary within the range of 5-80% w/v and the system pressure within the range of about 1-12 MPa, in particular between 2 and 10 MPa, such as more preferably in the range of about 2-6 MPa. The temperature in the reactor system 4 may vary within the range of 100-250°C, in particular in the range of 160 to 250°C. The hydrogen consumption in this embodiment is characterized as follows: Molar ratio makeup hydrogen to feed glycerin in a steady state operation is less than 1 : 1.
Reactor products leaving recuperative device 2 are now led to an additional cooler 5 and from there in a gas/liquid separator 6 that is operated at the system pressure. The gaseous stream from device 6 is treated separately in a special unit 7 where it is brought in direct contact with water in order to remove impurities from the gaseous effluent stream .
Purified gaseous effluent stream prior to entering discharging line P-200 is partially recycled to the system after elevating its pressure by a gas compression device 8. The remaining fraction of the purified effluent gas stream is discharged through line P-200. It can individually be traded or used for different purposes within the process.
Of special interest and preferred use is to use it as feedstock for hydrogen producing device of which hydrogen can be partially or fully used within the process. Other uses may be on the field of automotive gas fuel application.
The liquid escaping gas/liquid separator is now pressure released and led into an evaporator and distilling device 9 where solvent and alcohol rich fraction are removed and separated from the higher boiling liquid components. This operation can be done by means of conventional evaporation, distillation or rectification methods. The solvent is recycled to the feed blend section through line P-170.
Optionally the liquid product fluid enters a separate pressure releasing device prior entering the evaporation and distillation section. This may include another gas/liquid separator whereby additional fraction of dissolved gases can be recovered from the liquid stream and brought up to the system pressure and recycled . Higher boiling and solvent free fraction from device 9, containing among others ethylene glycol, propylene glycol and unreacted feedstock material now enters a product separation device 10 where ethylene glycol and propylene glycol are individually separated and purified, leaving a heavier boiling fraction to be recycled (line P-160) and a smaller fraction there from to be purged.
Suitable equipments for this operation are flash, falling or wiped film evaporators followed by one or more fractionation devices equipped with structural packing or sieve trays, thus realizing the necessary and suited quantities of effective separation steps.
Alternative process with secondary reactor:
Alternative process option is related to the special managing and treatment of gaseous byproducts. Here the perspectives, taking into consideration a process scheme according to Fig . 2. After being separated in a gas/liquid separator 6 the gases are fed to and compressed by a compressor 7. The compressor 7 may also optionally be served with additional hydrogen from main hydrogen feed line P-130, in order to balance the gas mixture in a desired way.
Now the compressed gas mixture is tempered and led into a separate gas phase reactor 8, filled with a solid catalyst, where the gaseous components partially undertake chemical reaction. (The desired reactor products are low boiling oxo-chemicals, especially methanol, thus providing an alternative route for the production of bio-methanol.)
Gases escaping reactor 8 are led to a combined cooler-gas/liquid separator 9 where condensed reactor products are separated in a liquid phase. The gases escaping the gas/liquid separator are tempered and pressure balanced in order to treat them in a gas separation device 10.
There the gases are split in two main gas fractions. The one contains enriched and concentrated methane, which is rejected from the system in line P-200. The other stream, here called a lean gas P-190, containing lower concentration of methane, is recycled through the compressor 7 to reactor 8. By this option no hydrogen is recycled to or through reactor 4. Separation of liquid products are realized in a series of evaporation, distillation and rectifying devices, using conventional technologies, operation steps 11 and 12. Separation processes makes use of thermal energy solely.
Gas phase reactor system 8, according alternative process arrangement, Fig. 2, can have a special configuration as shown by Fig. 3. The gaseous feed components are first led through a recuperative device 8a prior tempered to the desired entering temperature in a feed heater 8b.
Here the gases stream vertically upwards, or optionally downward, through a solid catalyst bed reactor 8c where chemical reactions between the feed gas components take place. The reactor is operated adiabatically. The gaseous reactor product gases are then partially cooled in recuperative device 8a, where product components may start condensing . The reactor product fluid escaping recuperator are then led to a separate cooler/condenser 9 (Fig 2.) for condensation and separation of reactor products. Thus the secondary reactor system is capable of increasing the overall yield of products and to deliver enhanced process and economic value to the operation.
Conventional process and operation conditions in the gas phase reactor 8 (Fig. 2) are;
Temperature 200-260°C, pressure 4,0 to 12 MPa. Typical hourly space velocity (GHSV) in the range between 500 and 7000 Nm3-feed/m3-catalyst per hour.
EXAMPLES
Example 1 to 6:
A series of studies were made with 1000 mL stainless steel reactor using catalyst filling of 500 mL (trickle bed arrangement). The reactor is heated by adapting clamped electrical heaters on the reactor body. Aqueous feed solution containing glycerol varied between 25 and 44 % in concentration. A solid catalyst used in those experiments was of the inventors own proprietary formulation, containing mainly nickel as active metal on acidic support, activated by conventional methods. The operation was continued for over 1250 hours without any signs of catalyst deactivation. Fresh hydrogen was supplied at a pressure between 2,0 and 9,0 MPa and the feed flow parameter LHSV varied between 0,5 and 3,0. Hydrogen to glycerin feed molar ratio was kept lower than 1 : 1. The analytical work was done using Techcomp GC equipped with a FID detector.
Table 1: Operational Parameters
Example No.
1 2 3 4 5 6
Inlet temperature °C 175 180 182 185 188 188
Pressure MPa 6,0 2,5 2,5 3,0 3,0 3,0
Feed cone. wt.% 44 34 34 30 30 30
Molar; (H2 :Glycerin)feed - 0,36 0,43 0,37 0,47 0,45 0,47
LHSV h"1 1,2 1,6 1,7 2,0 2, 1 2,1
NaOH g/L 5 4,7 4,0 4,0 4,0 4,0
Conversion % 43 61 56 62 62 65 Table 2: Product distribution wt. %(by calibration using standards)
Example No.
1 2 3 4 5 6
Acetone 0,2% 0,2% 0,2% 0, 1% 0, 1% 0,1%
Methanol 2,0% 1,3% 1,2% 1,2% 0,9% 1,0%
Ethanol 16,3% 13,3% 14,1% 12,1% 11,5% 11,5% n-Propanol 0,1% 0, 1% 0,1% 0,0% 0, 1% 0,1%
Hydroxyacetone 2,9% 3, 1% 4,5% 3,9% 4, 1% 2,8%
Propylene glycol 66,1% 68,2% 67,8% 71,0% 73,2% 75,0%
Ethylene glycol 11,8% 13,3% 11,4% 11,6% 10,1% 9,5%
Example 7:
Crude liquid products from experiments listed in table 1 were collected and subject to treatment in a rotating evaporating equipment (Buchi Rotavap) at reduced pressure (600 mbarabs). The overhead fraction was condensed and collected, which contains 2-6% w/v of alcohols in total.
Example 8:
Products from Example 7 were put into a simple laboratory still with a rectification device. The alcohols were concentrated by multiple batch distillation (atmospheric) by the separation of approx. 10 % overhead product ratio each time. The first overhead product contained 25-30 % w/v alcohol mixture. Second distillation of the first overhead product enabled the concentration of alcohols and oxo-chemicals with lower molecular weight than glycerin of over 93 % v/v. Example 9:
Residues from Example 8 were run through vacuum distillation in Rotavap equipment. Pressure was kept 10 mbara s and temperature 130°C. Evaporated material was condensed and collected . Overhead products contained propylene glycol, ethylene glycol, and some hydroxyacetone. Only traces of glycerol were noticed.
Example 10:
Gaseous effluent stream escaping reactor system in Example 2 containing impurities was led through a water column under system pressure. Some of the impurities are dissolving in water. Gas escaping the washing device showed hydrogen to methane molar ratio lower than 1 :2. Other impurities were lower than 2 % v/v in concentration. Example 11 :
Gaseous stream, reflecting an effluent process stream from compressor 7 in figure 2, is brought to an elevated pressure and temperature of approximately 6 MPa and 240°C respectively and passed through a fixed catalyst bed reactor containing CuO and ZnO.
About 25% of the carbon dioxide was converted in a single pass operation forming a product mixture containing a condensable methanol and water.
Example 12:
Gaseous stream, reflecting an effluent process stream from operation step 9 in figure 2, containing methane, hydrogen, water and carbon dioxide is passed through a hollow fiber gas membrane module. Water gas, hydrogen and carbon dioxide passes easily through the membrane wall, reflecting a process stream of P-190, also called a permeate, showing enriched concentration of those components compared with the feed gas mixture. The rejected stream, P-200, called a retentate, contains enriched concentration of methane, CH4, beside a lean concentration of water gas, hydrogen and carbon dioxide. Experiment results with over 95% concentration of methane in the retentate depending on process parameters were realized.

Claims

1 CLAIMS
1. A process for reacting a reactant feedstock that comprises glycerol, other sugar alcohols or any mixture thereof with hydrogen, for obtaining a product mixture comprising as major product components propylene glycol and ethylene glycol and one or more minor product components selected from one or more of C1-C3 alcohols, acetone and hydroxy-acetone, the process comprising feeding to a reactor charged with solid catalyst a reagent mix comprising
(i) said reactant feedstock,
(ii) a solvent, and
(iii) hydrogen gas,
wherein said reactor operates at a pressure in the range of about 1.0 to about 12.0 MPa, and wherein the molar ratio of said feed hydrogen gas to said reactant feedstock is below 1 : 1.
2. The process of claim 1, wherein said one or more minor product components comprise at least 3 wt% of the total combined amount of obtained said major components and said one or more minor components.
3. The process of any of the preceding claims, wherein the molar ratio of said feed hydrogen gas to said reactant feedstock, converted, is below about 1 : 2.
4. The process of any of claims 1 to 3, further comprising feeding at least one of the reactant components (i)-(iii) through a two-way recuperator which receives as counter stream the product stream from said reactor, to heat one of said at least one of the reactant components (i)-(iii) and to cool said product stream .
5. The process of any of the preceding claims, wherein said reagent mix further comprises (iv) an alkali metal hydroxide as co-catalyst.
6. The process of any of the preceding claims, wherein said solvent comprises water.
7. The process of any of the preceding claims, wherein said reactor operates at a pressure below about 3.45 MPa gauge, and a temperature below 210 °C.
8. The process of any of the preceding claims, wherein said reactant feedstock is in a mixture with a solvent, wherein the solvent has a concentration of more than 50% by weight in the reactant feedstock solvent mixture.
9. The process of any of the preceding claims, further comprising :
- separating the cooled product stream into a liquid phase fraction which comprises said major products components and minor products components, a gas phase fraction, and 2
- feeding said gas phase fraction to a purification unit bringing it in contact with water, for removal of undesired gas component(s) from said gas phase fraction, leaving a purified gas phase effluent comprising one or more organic gas phase components and unreacted hydrogen gas.
The process of claim 9, further comprising one or more steps for separating components of said liquid phase fraction.
The process of claim 9, further comprising recycling said purified gas phase effluent into said reagent mix.
12. The process of claim 8, wherein said purified gas phase effluent is used as a feedstock for hydrogen production, combustion, fed to a gas distribution network or compressed for automotive fuel application.
13. A process of claim 8, where no gas from said gas phase fraction is recycled back to said reactor.
14. The process of any of claims 1-6, further comprising
- separating the cooled product stream into a liquid phase fraction which comprises said major products components and minor products components, a gas phase fraction, and
- raising the temperature and pressure of said gas phase fraction and feeding to a separate gas phase secondary reactor containing fixed bed catalyst.
15. The process of claim 14, wherein additional hydrogen is admixed to said gas phase fraction.
16. The process of claim 14, where said gas phase fraction is led through a two-way recuperator which receives as counter stream the product stream from said reactor, to pre-heat the reactant components and to cool said product stream.
The process of any of claims 14 to 16, where the product stream from said secondary reactor contains at least one mono-hydroxy alcohol.
18. The process of claim 14 to 16, where the product stream from said secondary reactor is brought to a combined cooling and gas/liquid separation device.
19. The process of claim 18, where separated gas from said gas/liquid separation device is
further treated in a gas separation device.
20. The process of claim 19, where the separation device contains molecular sieve or polymer gas membrane separation unit. 3
21. The process of claim 14, where organic gas phase components from the product stream from said secondary reactor are concentrated and rejected from the process, leaving a lean gas fraction with enriched concentration of inorganic gas components.
22. The process of claim 21, where the concentrated organic gas fraction, containing one or more inorganic gas component impurities, is used as a feedstock for hydrogen production, combustion, fed to gas distribution network or compressed for automotive fuel application.
23. The process of claim 22, where said lean gas fraction is recycled to said secondary reactor.
24. The process of claim 14, where the catalyst comprises copper, zink, nickel, cobalt, iron, ruthenium, platinum, palladium, mangan or molybenum.
25. The process of any of the preceding claims wherein said one or more minor product
components consists of one or more of methanol, ethanol, isopropanol, n-propanol, acetone and hydroxyacetone.
26. The process of any of the preceding claims wherein said reactant feedstock is obtained as a side product from biodiesel production.
27. The process of any of the preceding claims, wherein said reactant feedstock comprises one or more of glycerin, sorbitol, mannitol, arabinitol, xylitol, erythritol, maltitol, and lactitol.
28. The process of any of the preceding claims, wherein the operating temperature of said reactor is in the range of about 170° to about 220°C.
29. The process of any of the preceding claims, wherein said catalyst comprises a transition metal selected from one or more of palladium, platinum, ruthenium, chromium, nickel, copper, zinc, iron, rhodium, mangan and molybdenum, and combinations thereof, deposited on a support substrate.
30. The process of any of the preceding claims, wherein said reactor charged with catalyst has trickle bed configuration.
31. The process according to any of the preceding claims, wherein heating and liquid product separation isolation is realized by means of applying thermal energy and no use of ion exchange or membrane separating devices.
32. The process according to claim 31, wherein the source of thermal energy is geothermal.
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