Classifications

• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11C—FATTY ACIDS FROM FATS, OILS OR WAXES; CANDLES; FATS, OILS OR FATTY ACIDS BY CHEMICAL MODIFICATION OF FATS, OILS, OR FATTY ACIDS OBTAINED THEREFROM
  • C11C3/00—Fats, oils, or fatty acids by chemical modification of fats, oils, or fatty acids obtained therefrom
  • C11C3/003—Fats, oils, or fatty acids by chemical modification of fats, oils, or fatty acids obtained therefrom by esterification of fatty acids with alcohols
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
  • B01J23/002—Mixed oxides other than spinels, e.g. perovskite
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
  • B01J23/10—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of rare earths
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
  • B01J37/02—Impregnation, coating or precipitation
  • B01J37/03—Precipitation; Co-precipitation
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C67/00—Preparation of carboxylic acid esters
  • C07C67/03—Preparation of carboxylic acid esters by reacting an ester group with a hydroxy group
• • 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
  • C10L1/02—Liquid carbonaceous fuels essentially based on components consisting of carbon, hydrogen, and oxygen only
  • C10L1/026—Liquid carbonaceous fuels essentially based on components consisting of carbon, hydrogen, and oxygen only for compression ignition
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2523/00—Constitutive chemical elements of heterogeneous catalysts
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J35/00—Catalysts, in general, characterised by their form or physical properties
  • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
  • B01J35/64—Pore diameter
  • B01J35/647—2-50 nm
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J35/00—Catalysts, in general, characterised by their form or physical properties
  • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
  • B01J35/66—Pore distribution
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
  • C10G2300/00—Aspects relating to hydrocarbon processing covered by groups C10G1/00 - C10G99/00
  • C10G2300/10—Feedstock materials
  • C10G2300/1011—Biomass
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E50/00—Technologies for the production of fuel of non-fossil origin
  • Y02E50/10—Biofuels, e.g. bio-diesel
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P30/00—Technologies relating to oil refining and petrochemical industry
  • Y02P30/20—Technologies relating to oil refining and petrochemical industry using bio-feedstock

Definitions

• the present invention relates to a multi-step process for the preparation of fatty acid alkyl esters.
• Fatty acid alkyl esters in particular the methyl esters, are important intermediates in oleochemistry.
• Europe alone over 4 million tonnes of vegetable oil methyl ester are produced annually as starting materials, especially for surfactants.
• fatty acid methyl esters are becoming increasingly important as fuel for diesel engines.
• Technical processes for the preparation of fatty acid alkyl esters, in particular fatty acid methyl esters, are nowadays carried out almost exclusively using catalysts.
• reaction steps carried out in the context of the processes are predominantly esterification reactions or transesterification reactions which in each case require other preferred catalyst systems and reaction conditions.
• basic catalysts e.g., alkali hydroxides, alcoholates, oxides, carbonates, anion exchangers
• acid catalysts e.g., mineral acids, p-toluenesulfonic acid, boron trifluoride, cation exchangers
• enzymes lipases
• acidic catalysts can be used as catalysts for the esterification.
• the reaction starts with a two-phase system of triglyceride and alcohol.
• a homogeneous phase is formed, which in the the further course with increasing glycerol formation is in turn biphasic, wherein the light phase of the crude fatty acid alkyl esters and the heavy phase is a glycerol-rich phase.
• the esterification is characterized by a generally lower than the transesterification necessary reaction temperature, which depends in a significant way on whether a catalyst and, if so, which catalyst is used.
• the phase ratios of pure esterification are generally simpler than those of transesterification.
• this simplification is often compensated by appropriate purification steps before carrying out the esterification.
• WO 2007/012097 discloses a process in which carboxylic acid esters can be prepared by means of a transesterification or esterification reaction by means of a liquid metal catalyst comprising an alkaline earth metal salt of a carboxylic acid.
• the process is always characterized by the need to separate the catalyst from the respective reaction product, since this should either be reused in the process, or the product would not be commercially useful with the catalyst.
• the disclosed catalyst is a liquid catalyst, the processes disclosed to be useful in separating the catalyst are cumbersome and thus make the entire process economically disadvantageous.
• the possibility of a membrane process is also explained, which according to the disclosure can also be applied to the separation of the glycerol phase from the fatty acid ester phase.
• WO 2006/029655 discloses a process for the transesterification of starting materials, which likewise comprises salts as catalysts.
• the problem of separation of a catalyst from the reaction mixture within the process is solved here by the use of salts which are characterized by being insoluble in alcohols and fatty acids and only sparingly soluble in water are.
• the salts are selected so that they decompose under reaction conditions, so that they can no longer be found in the reaction product in a disturbing concentration.
• the method is further characterized in that an esterification of free fatty acids of the starting materials according to the disclosure is possible simultaneously with a transesterification.
• the amount of catalyst used should be increased in accordance with the proportion of free fatty acids, the catalyst used for this purpose being according to the disclosure inactivated and therefore having to be renewed. Separation of the glycerol phase from the reaction product is disclosed only by means of a separating funnel. Overall, the disclosed method is described by the Restrictions on the catalyst consumption of starting materials with an increased proportion of free fatty acids can not be used efficiently and lack of suitable methods to provide the resulting reaction product in an economically advantageous manner and sufficient product purity.
• WO 1998/56747 discloses a process for the transesterification of starting materials which uses heterogeneous basic catalysts.
• these heterogeneous basic catalysts include oxides of alkaline earth metals.
• the transesterification reaction of the process is carried out at temperatures between 25 and 260 ° C. at ratios of alcohol to triglyceride of 0.2 to 20 and a proportion of between 0.05 and 10% of the catalyst over the entire reaction mixture.
• the catalyst is used in the form of a powder, resulting in a suspension reaction.
• WO 2006/050925 a method is disclosed which also uses a heterogeneous basic catalyst, under whose presence the starting materials with monoalcohols at temperatures between 100 0 C and 250 0 C and at ratios of monoalcohol to starting material between 4 and 30 to fatty acid esters and Glycerol be reformed.
• the reaction can also be carried out in the form of a fixed bed reaction.
• the starting materials may contain more than 1% by weight of free fatty acid.
• the disclosed process becomes very disadvantageous in its yield when increased levels of free fatty acids are contained in the starting materials, since the disclosed catalyst does not catalyze the esterification reaction of the free fatty acids, or only to a small extent.
• No. 5,908,946 discloses a process by means of which fatty acid alkyl esters and glycerol can be obtained in high purity in 1 to 3 stages.
• the disclosed process uses a basic catalyst comprising zinc oxide and can be continuously packed in a fixed bed - A -
• transesterification reaction is preceded by an esterification reaction with glycerol, which is characterized in that glycerides are preferably formed in it which will subsequently be transesterified.
• the separation of the liberated in the transesterification glycerol is carried out according to the disclosure by decantation.
• a disadvantage of this process is the fact that, as is known, basic catalysts catalyze the esterification worse than acidic catalysts, so that high impurities of the starting materials with free fatty acids again lead to greatly reduced conversions and yields based on the fatty acid alkyl ester.
• the separation process of decantation is a process based on the phase separation of two liquids based on a density divergence and a mutual, poor solubility.
• a solution of two liquids can never be prevented, since there always exists a distribution coefficient of the two phases which represents a real number (see, for example, Klaus Sattler, "Thermal Separation Methods", Wiley VCH, 3rd ed. ISBN 10: 3-527-30243-3)
• the purity of the ester phase and the purity of the glycerol phase may not be sufficient after decantation, but may not be further improved during the decantation separation process.
• a process for the preparation of fatty acid alkyl esters starting from starting materials which comprise at least a proportion of triglycerides of fatty acids and / or a proportion of free fatty acids, which is characterized in that it comprises at least the steps:
• step b) optionally separating water and / or alcohol from the product of step a),
• step c) conversion of the triglycerides with an alcohol to fatty acid alkyl esters in the presence of a basic, heterogeneous catalyst, in the form of a transesterification reaction, d) optionally separating the alcohol from the product of step c),
• Starting materials in the context of the present invention, all substances which comprise at least a proportion of triglycerides of fatty acids and / or a proportion of free fatty acids.
• Possible starting materials are, for example, oils and fats of vegetable or animal origin, such as rapeseed oil, soybean oil, palm oil or jatropha oil as vegetable oils, or coconut fat as vegetable fat, or fish oil as oil of animal origin, and beef tallow, or lard as fats of animal origin.
• fatty acids are meant for this invention monocarboxylic acids, ie compounds consisting of a carboxyl group and a hydrocarbon chain, wherein the hydrocarbon chain comprises at least ten carbons.
• the hydrocarbon chain may be branched or unbranched. That the carbons of the hydrocarbons may be lined up linearly or not.
• the hydrocarbon chain may be saturated or unsaturated. That in each case between the at least ten carbon atoms of the hydrocarbon chain, the covalent bond can comprise one or more bonding electron pairs.
• the group of substances known to the person skilled in the art under the name "lipids" is also counted in connection with the present invention.
• Preferred fatty acids are saturated or unsaturated monocarboxylic acids comprising between 14 and 20 carbons in the hydrocarbon chain.
• esters are often the major constituents of the starting materials exemplified above.
• Free fatty acids are fatty acids that are additionally characterized by the fact that they are not the result of any of the reactions of this invention.
• Alcohols according to the process of the invention usually monoalcohols comprising a maximum of five carbon atoms are used. Preference is given to monoalcohols having one to four carbon atoms, such as, for example, methanol, ethanol, 1-propanol, 2-propanol, etc. Particular preference is given to methanol.
• the acidic, heterogeneous catalyst used in the inventive step a) usually comprises polymers having acidic side groups. Preference is given to acidic ion exchange resins. Sold by Rohm and Haas under the trade name Amberlyst ® acidic ion exchange resins are particularly preferred.
• the acidic, heterogeneous catalyst according to the invention can be present in the form of particle beds or in monolithic form. Preference is given to particle beds. Particular preference is given to particle beds of the acidic, heterogeneous catalyst which are present as a fixed bed in the reaction zone. Most preferably, the particles of the acidic, heterogeneous catalyst in this case have a mean diameter of about 800 microns.
• the skilled person is well aware of the methods and devices with which he can represent a fixed bed in the reaction zone. As a non-conclusive example is the fixation of the particle bed of acidic, heterogeneous catalyst by sieves of smaller mesh size, called the diameter of the particles of the acidic, heterogeneous catalyst.
• a fixed bed comprising particle beds is particularly advantageous since it allows a high surface area of the acidic, heterogeneous catalyst to be achieved in the reaction zone at which the conversion can be carried out according to step a) of the invention.
• the reaction product is not with residues of the acidic, heterogeneous
• the conversion according to step a) of the process according to the invention can, at temperatures between 50 0 C and 120 0 C take place. Temperatures between 60 0 C and 100 0 C., are preferred Particularly preferred is a temperature of about 85 ° C.
• the conversion according to step a) of the process according to the invention can be carried out at pressures between 1 bar and 10 bar.
• a pressure between 2 bar and 7 bar.
• the stated and preferred pressures according to the invention result from the vapor pressures of the particular alcohols used, e.g. Ethanol or methanol at the inventive and preferred temperatures of the process.
• Lower pressures lead to outgassing of the alcohol from the reaction solution, so that it is no longer fully available for the reaction of the acid, heterogeneous catalyst.
• Higher pressures are energy intensive and thus may be economically unfavorable.
• the conversion according to step a) of the process according to the invention can also preferably be carried out at a pressure approximately corresponding to the vapor pressure of the alcohol used in the process at the temperatures according to the invention or preferred.
• the pressure in step a) of the process according to the invention is slightly higher than the vapor pressure of the alcohol used in the process at the temperatures according to the invention or preferred.
• the residence time of starting material comprising the free fatty acids and alcohol in step a) of the inventive method is usually between 5 and 40 minutes.
• the residence time is preferably between 10 and 20 minutes.
• Residence time in the context of the invention eg in the case of a discontinuous conversion
• the time duration of the reaction solution in the apparatus in which the conversion is carried out according to step a) of the inventive method or (eg in the case of a continuous conversion) the average time of entering a fluid element in the reaction zone in which the conversion is carried out according to step a) of the inventive method, until the exit of the same fluid element from the reaction zone.
• step a) of the process according to the invention can be carried out continuously or batchwise.
• step a) of the process according to the invention is carried out continuously.
• the residence times are matched to the boundary conditions of the process according to the invention (for example pressure, temperature, amount of alcohol, etc.) and, based on this, represent conventional and preferred values which together advantageously solve the object of the invention.
• step a) of the process according to the invention is usually carried out at a molar ratio of 1: 1 to 40: 1 of the alcohol used to the free fatty acids contained in the starting material.
• a molar ratio of 10: 1 to 30: 1 is preferred, and a molar ratio of about 20: 1 is particularly preferred.
• a lower molar ratio of alcohol to free fatty acid than 1: 1 is unfavorable because even the stoichiometric conversion to fatty acid alkyl esters can not be achieved thereby.
• Higher molar ratios of alcohol to free fatty acid are disadvantageous because in at least one of the later steps at least the alcohol must be separated from the residual product. Separation operations always require the introduction of energy into the system which is to be separated, according to principles well known to those skilled in the art, whereby an increase in the molar ratio above a level still capable of appreciably positively affecting the conversion is economically unfavorable.
• the upper limit of the molar ratio of alcohol to free fatty acid is an economically reasonable limitation, in their further increase the conversion can not be increased significantly under the other given boundary conditions of the method according to the invention.
• step a) of the process according to the invention and its preferred variants disclosed herein achieve a conversion based on the free fatty acids of at least 90%. Taking into account the preferred embodiments and further developments of the process according to the invention, by means of step a) even a conversion based on the free fatty acids of at least 97% is achieved.
• step a) of the process according to the invention comprises at least one further conversion. Particularly preferred is a further turnover.
• the further conversion comprises at least one conversion according to step a) and its preferred embodiments with regard to pressure, temperature, residence time, acidic, heterogeneous catalyst and at least one prior separation of water and / or alcohol.
• the separation can be carried out by methods known to those skilled in the art, such as distillation, or according to steps b) and / or e) of the process according to the invention and is preferably carried out so that the remaining material stream less than 2 wt .-%, more preferably less than 0.05 wt .-% water.
• Preferred is an embodiment according to the preferred variants of steps b) and / or e).
• the means for achieving the required levels of water are well known.
• the water is separated off and the entire remaining stream is fed to the at least one further conversion, optionally with the addition of further alcohol. If further alcohol is added, which is particularly preferred, the amount of alcohol removed by the separation is very particularly preferably added again.
• step b) of the method according to the invention e.g. provided in the context of at least one further conversion according to a preferred development of step a) of the process according to the invention, this can be done by methods known to the person skilled in the art, such as distillation, or by means of a membrane process.
• a separation according to step b) is provided before carrying out step c) of the process according to the invention.
• a separation according to step b) by means of a membrane process, operated by the skilled person known methods to achieve the desired separation result, as has been previously disclosed, for example, with a maximum of 2 wt .-% water in the remaining stream.
• a separation according to step b) so that less than 20,000 ppm of water in the remaining stream from step b) are included.
• the separation according to step b) of the process according to the invention can be carried out continuously or batchwise. Preferably, the separation is carried out continuously.
• the conversion according to step c) of the process according to the invention is carried out using a basic, heterogeneous catalyst, usually salts and / or oxides of the metals selected from the list aluminum, calcium, chromium, iron, gallium, cobalt, copper, lanthanum, magnesium, manganese , Nickel, vanadium, zinc and mixtures thereof.
• Basic, heterogeneous catalysts will preferably comprise the oxides and / or salts, carbonates or hydroxy carbonates of these metals, as well as mixtures thereof.
• Particularly preferred basic, heterogeneous catalysts are substances which are obtained from hydrotalcites by calcination.
• Hydrotalcites denote layer minerals of trivalent and divalent cations of metals such as aluminum and magnesium, as known to those skilled in general, for example, under the chemical formula Mg6Al 2 (C ⁇ 3) (OH) i 6 ⁇ 4 H 2 O known. Hydrotalcites can be prepared with different ratios of metals Me 3+ and Me 2+ . In connection with the present invention also pyroaurite, sjörgrenite, manasseite, Stichit and the substances according to formula (I):
• Me 2+ may be divalent cations of the metals magnesium, calcium, iron, nickel, chromium, manganese, zinc, cobalt or copper and
• Me 3+ trivalent cations of the metals aluminum, iron, nickel, chromium, cobalt, gallium or vanadium may be referred to as hydrotalcites.
• Calcination in the context of the present invention, refers to the heating of eg hydrotalcites to obtain mixed oxides. Further heating in the course of heating leads to a structural rearrangement of the mixed oxides containing spinel structures of the mixed oxides.
• the particularly preferred basic, heterogeneous catalysts obtained from calcination of hydrotalcites are usually characterized by an at least partial rearrangement of the mixed oxides to the spinel structure.
• the Kalziniem is usually carried out at temperatures of 400 0 C to 1100 0 C.
• Step c) of the process uses a basic heterogeneous catalyst comprising lanthanum oxide (La 2 O 3 ) and alumina (Al 2 O 3 ) and optionally magnesium oxide (MgO) and the characterized in that the sum of the mass fractions of lanthanum oxide and magnesium oxide is between 2 and 20%.
• a basic heterogeneous catalyst comprising lanthanum oxide (La 2 O 3 ) and alumina (Al 2 O 3 ) and optionally magnesium oxide (MgO) and the characterized in that the sum of the mass fractions of lanthanum oxide and magnesium oxide is between 2 and 20%.
• the sums of the mass fractions of lanthanum oxide and magnesium oxide on the catalyst in the context of the present invention designate mass fractions of La 2 C 1 and MgO of the total catalyst mass calculated from the mass of lanthanum and magnesium in the catalyst.
• the mass fractions of lanthana and magnesia should therefore not be understood as limiting the actual presence of the pure oxide phases. This also applies below to statements relating to other constituents of the catalyst according to the invention, such as aluminum as aluminum oxide (Al 2 O 3 ).
• the sum of the mass fractions of lanthanum oxide and magnesium oxide is between 5 and 20%. Particularly preferably between 8 and 15%.
• the catalyst according to the preferred alternative embodiment may also contain only lanthana and alumina. However, the catalyst preferably contains lanthanum oxide, magnesium oxide and aluminum oxide.
• alumina can serve as a support with respect to the other two oxides low basic properties and can form stable mixed phases with two other oxides.
• the catalyst according to the preferred alternative embodiment contains between 5 and 15 wt .-% of lanthanum oxide and between 1 and 10 wt .-% magnesium oxide, so that in total but not more than 20 wt .-% of the two oxides are present ,
• the catalyst contains between 8 and 12% by weight lanthanum oxide and less magnesium oxide than lanthanum oxide.
• Such catalysts are particularly advantageous since the lanthana with alumina then forms stable mixed phases and the magnesium with the alumina can then form stable mixed phases which, although compared to the mixed phase of the lanthanum oxide with the alumina is not so stable against "leaching" the above, but is stabilized by the lanthanum oxide and alumina mixed phase.
• Leaching in the context of the present invention refers to the tendency of basic, heterogeneous catalysts to partially dissolve under the reaction conditions or itself with the reaction mixture to form reaction products, which are recovered in the reaction product.
• the catalyst is at least partially present in a perovskite mixed phase of the lanthanum and alumina and optionally the magnesium and alumina at least partially present in a spinel mixed phase.
• lanthanum and aluminum oxide is present at least partially in a perovskite mixed phase and magnesium and aluminum oxide at least partially in a spinel mixed phase.
• the alumina is present at least partially as ⁇ -AI 2 O 3 and the mass fraction of magnesium oxide is 0%.
• such a catalyst has a proportion of at least 80% mesopores, preferably a proportion of at least 90% mesopores.
• Mesopores in the context of the present invention designate pores having a diameter of 2 nm to 50 nm.
• the proportion of mesopores can be readily determined by methods well known to those skilled in the art, such as mercury porosimetry.
• Such a proportion of mesopores is particularly advantageous, because in this way an optimum of specific surface area of the catalyst can be achieved in comparison to the simple penetrability of the pore volume.
• the catalyst has a high specific surface area, but the pore channels are so small that the reactants reach the active centers of the catalyst more slowly, negatively impacting rapid conversion in the presence of the catalyst.
• the particularly preferred in this alternative embodiment described catalysts are especially particularly advantageous because they preferred an activity calculated from sales of fats and oils per unit time and per mass of catalyst greater than 0.2 kg / kg ⁇ ataiysato r 'h> in Embodiments of FIGS. 2 to 12 enable.
• All basic, heterogeneous catalysts according to the invention can be present in the form of particle beds or in monolithic form. To be favoured
• Particle beds Particular preference is given to particle beds of the basic, heterogeneous
• Catalyst which are present as a fixed bed in the reaction zone.
• the particles of the basic, heterogeneous catalyst have an average diameter of about
• step c) of the process according to the invention can, at temperatures between 50 0 C and 250 0 C take place. Temperatures between 180 ° C. and 220 ° C. are preferred. A temperature of about 200 ° C. is particularly preferred.
• step c) of the process according to the invention can be carried out at pressures between 1 bar and 150 bar. Preference is given to a pressure between 25 bar and 75 bar. Particularly preferred is a pressure of about 50 bar.
• the indicated pressures of the invention and preferred pressures result from the vapor pressures of the particular alcohols used, e.g. Ethanol or methanol at the inventive and preferred temperatures of the process.
• Lower pressures lead to outgassing of the alcohol from the reaction solution, so that it is no longer fully available for the reaction of the basic, heterogeneous catalyst.
• Higher pressures are energy intensive and thus may be economically unfavorable.
• the conversion according to step c) of the method according to the invention also preferably at a pressure about corresponding to the vapor pressure of the alcohol used in the process at the inventive or preferred temperatures can be performed.
• the pressure in step c) of the process according to the invention is slightly higher than the vapor pressure of the alcohol used in the process at the temperatures according to the invention or preferred.
• the residence time of starting material comprising the triglycerides and alcohol in step c) of the process according to the invention is usually between 5 and 90 minutes.
• the residence time is preferably between 20 and 50 minutes.
• the time duration of the reaction solution in the apparatus in which the conversion is carried out according to step c) of the method according to the invention comprise, or (eg in the case of a continuous turnover) the average time of entry a fluid element in the reaction zone, in which the conversion is carried out according to step c) of the method according to the invention, until the exit of the same fluid element from the reaction zone. Consequently, the conversion according to step c) of the process according to the invention can be carried out continuously or batchwise. Preferably, step c) of the process according to the invention is carried out continuously.
• the residence times are matched to the boundary conditions of the process according to the invention (for example pressure, temperature, amount of alcohol, etc.) and represent normal and preferred values based thereon. If the boundary conditions of step c) of the process according to the invention change, the person skilled in the art can thus easily without further inventive step to make a corresponding adjustment of the residence time by specific experiments in order to achieve the disclosed results of step c) of the method according to the invention.
• boundary conditions of the process according to the invention for example pressure, temperature, amount of alcohol, etc.
• step c) of the inventive method is usually carried out at a molar ratio of 3: 1 to 30: 1 of the alcohol used to the triglycerides contained in the starting material. Preference is given to a molar ratio of 5: 1 to 25: 1, particularly preferably a molar ratio of about 23: 1.
• a lower molar ratio of alcohol to triglycerides than 3: 1 is unfavorable because only in exceptional cases can the stoichiometric conversion to fatty acid alkyl esters be achieved (for example, if the triglycerides according to the invention have only a maximum of two ester bonds).
• Higher molar ratios of alcohol to triglycerides are disadvantageous because in at least one of the later steps, at least the alcohol must be separated again from the remaining product. Separation operations always require the introduction of energy into the system which is to be separated according to principles generally known to the person skilled in the art
• Ratio of alcohol to triglycerides is an economically reasonable limitation, in their further increase the conversion can not be significantly increased under the other given boundary conditions of the method according to the invention.
• step c) of the process according to the invention and its preferred variants disclosed herein achieve a conversion based on the triglycerides of at least 80%. Taking into account the preferredHarsforrnen and further developments of the method according to the invention, achieved by means of step c) even a conversion based on the triglycerides of at least 90%.
• step c) of the process according to the invention comprises a further conversion.
• This can be as well as sales according to step c) are carried out continuously or discontinuously.
• the further conversion is carried out continuously.
• the further conversion comprises a conversion according to step c) and its preferred embodiments in terms of pressure, temperature, residence time, basic, heterogeneous catalyst and a prior separation of glycerol.
• the separation is usually carried out by means of a multi-stage procedure, comprising flash evaporation and subsequent separation of glycerol by means of phase separation.
• Flash evaporation is usually performed in devices well known to those skilled in the art, such as falling film evaporators.
• the flash evaporation is preferably carried out so that the proportion of the alcohol is reduced so that the solubility of the glycerol in the alcohol is below.
• the alcohol is preferably condensed and fed to either step a) or step c) of the inventive method.
• the separation of glycerol by means of phase separation is preferably carried out at temperatures between 60 0 C and 15O 0 C. Also preferably, the phase separation, as in step a), carried out at a pressure corresponding to the vapor pressure of the alcohol. More preferably, the pressure is slightly higher than the vapor pressure of the alcohol used in the process.
• the glycerol is preferably fed to step e) of the process according to the invention.
• further alcohol is added to the further reaction after separation.
• the amount of alcohol removed during the separation is supplied again.
• Methods of determining the amount of alcohol removed are well known and include e.g. Measurement of the refractive index of the discharged material flow.
• step d) of the inventive method is particularly advantageous, because in this way the conversion based on the triglycerides can be further increased, which solves the task of high space-time yield with further consideration of the purity of the process product particularly advantageous.
• the separation of the alcohol according to step d) of the process according to the invention is preferred because the alcohol is miscible with fatty acid alkyl ester and at the same time is a solvent of glycerol.
• the step e) according to the invention comprises a liquid-liquid separation using a hydrophobic membrane. It is intrinsic to this method that its separation result depends, inter alia, on the presence of two separate fluid phases. Thus, if the proportion of alcohol in step e) of the feed stream according to the invention is too high, there are no separate fluid phases and the separation result of step e) of the process is unfavorable.
• the hydrophobic membrane used in step e) according to the invention is usually a polymer or ceramic membrane or a membrane made of a polymer-ceramic composite.
• Particularly preferred are hydrophobic membranes of ceramic, polymer, or composites of polymer and ceramic, which have a coating of hydrophobic material, e.g. perfluorinated polymers (PTFE, PVDF) or hydrophobic polymers (polypropylene) or whose surface has been rendered hydrophobic by the use of isocyanates or silanes.
• the hydrophobic membrane exhibits a high separation rate between the product phase comprising the polar glycerin and the non-polar fatty acid alkyl ester, the latter being able to permeate through the membrane and the former not.
• the hydrophobic membrane may have a pore size of 0.05 .mu.m to 10 .mu.m, preferably from 0.1 .mu.m to 5 .mu.m.
• one of the membranes according to the invention or preferred is particularly advantageous because it may cause the impurities (e.g., salts, etc.) present in the stream to remain in the polar phase and not be present in the product, the fatty acid alkyl esters.
• impurities e.g., salts, etc.
• the separation according to step e) of the process according to the invention can be carried out continuously or batchwise. Preferred is a continuous separation.
• the separation according to step e) is particularly advantageous because it allows glycerol to be obtained in a highly pure form, which is either sold directly, thus increasing the economy of the process according to the invention, or converting it into a further conversion either into a usable form in the process according to the invention is converted or converted into a higher quality substance, which is then sold.
• steps a) and c) of the method according to the invention need not be carried out successively in the order implied by the illustration given above. Rather, this presentation describes only the necessarily characterizing process steps of the inventive method. Steps a) and c) may be e.g. also be carried out parallel to each other. In addition, preferred embodiments and further developments of the method according to the invention are disclosed, which further explain this.
• step f) a separation according to step f) is carried out, in which free fatty acids are separated from triglycerides, so that the free fatty acids correspond to step a) and the triglycerides to step c) of the inventive Method be supplied simultaneously.
• the separation according to step f) is preferably carried out by stripping and subsequent condensation of the stripping gas.
• the stripping gas used is preferably water vapor. Stripping is a process which is generally known to the person skilled in the art and which is characterized by the entrainment of substances from mixtures of substances by means of a gas or gas mixture.
• the stripping takes place at a pressure of 2 to 5 mbar. Also particularly preferred stripping takes place at a temperature of 230 0 C to 270 0 C.
• the subsequent condensing of the stripping gas is preferably carried out in two stages and comprises in a first stage the condensation of optionally entrained impurities, such as triglycerides and in a second stage, the condensation of the free fatty acids.
• the condensate comprising the free fatty acids is fed to step a) of the process according to the invention.
• step f) is advantageous since it can thus be avoided that the triglycerides, which are substantially inert for step a) of the process according to the invention, have to pass through this process step without conversion. Due to the increased amount of the material stream to be passed through step a) of the process according to the invention, the devices in which this step is carried out would have to be dimensioned larger, without a turnover of the triglycerides taking place to any significant extent in this step. This would be economically unfavorable. Thus, the implementation of step f) solves the task of obtaining a high space-time yield in a particularly advantageous manner.
• a further step g) is carried out after step e) of the process according to the invention, which is characterized in that the glycerol obtained from step e) is supplied to a further conversion.
• the further conversion is a combustion. The generated in the combustion
• Provision of the necessary for operating the inventive steps a) and / or c) temperature is used.
• step g) comprises reactions other than those of the combustion.
• step g) as combustion is particularly advantageous, because in this way the energy expenditure which must flow from the exterior to the method according to the invention is reduced and thus the operating costs of the method are reduced.
• the product obtained from the process is present in high yield and purity, so that it can preferably be used directly, or after addition of additives for its refinement, as a fuel for diesel engines.
• a method according to the invention is shown in which first the starting material, for example animal or vegetable oils and / or fats, or mixtures thereof in a first step to a first separation (1) are subjected, in the free fatty acids of triglycerides be separated. Possible embodiments of this separation are, for example, stripping with steam, etc.
• the triglycerides obtained are then converted (transesterification) and the resulting free fatty acids are added to a conversion (esterification). Both the conversion (transesterification) and the conversion (esterification) alcohol (eg methanol) is supplied.
• the product of conversion (transesterification) and conversion (esterification) is fed to a separation (2), for example in the form of alcohol distillation, so that the separated alcohol can optionally be recycled to the alcohol.
• the two-phase product resulting from separation (2) is then subjected to separation (membrane process) so that two streams of fatty acid alkyl ester and glycerol are recovered in pure form.
• FIG. 2 shows a preferred further development of the method according to the invention, in which first the starting material is again subjected to a first step in the form of a separation (1), so that again free fatty acids are separated from triglycerides.
• the triglycerides are then fed to a conversion (transesterification), the product stream from this first conversion (transesterification) is subjected to separation (2), e.g. in form of a
• Material flow is separated. This alcohol can then be recycled to the reservoir of alcohol and reused in the process. The remaining material stream is then a separation
• Glycerol is separated.
• Stream from the separation (5) a separation (4), e.g. fed in the form of alcohol distillation.
• the further conversion (transesterification) is in turn the alcohol in the separation (2) and optionally separating (5) lost again.
• the free fatty acids resulting from the separation (1) are first fed to a conversion (esterification) together with alcohol.
• the product of the conversion (esterification) is then a separation (3), for example in the form of an evaporation supplied in the optionally alcohol and water, which is formed during the conversion (esterification), from the remaining stream comprising free fatty acids are separated.
• the material stream comprising free fatty acids is fed to further conversion (esterification) with further addition of alcohol, while the separated material stream optionally comprises alcohol and water the separation (4) are supplied.
• the separation (4) then separates the material streams which have been combined in this step into alcohol, which can be fed to the reservoir and optionally reused in the process and the residual material stream comprising fatty acid alkyl esters and glycerol, so that they are present in different phases.
• This two-phase system is then fed to the separation (membrane process), from which then glycerol and fatty acid alkyl esters are obtained in pure form.
• the mixture was subsequently dried at 150 ° C. for 3 h. Subsequently, the solid was at 700 0 C with a temperature ramp of 7 ° C / min. heated. The final temperature of 700 0 C was held for 2 h. Finally, the solid was calcined for 4 h at 1000 0 C.
• the resulting catalyst was converted into a soluble form by means of microwave digestion (DIN EN 14084).
• the content was determined by means of ICP-OES with a Perkin Elmer (Optima 3300 XL) device analogously to DIN EN ISO 11885 and gave the composition according to Table 1.
• the powder was characterized by powder X-ray diffraction (p-XRD).
• p-XRD powder X-ray diffraction
• Siemens D 5000 Siemens D 5000 was used.
• the measurement parameters according to Table 3 were used.
• the alumina designated 00-001-1303 according to the nomenclature of the International Center for Diffraction Data is ⁇ -AJ 2 O 3 .
• the obtained catalyst powder was further used to determine its content
• a 1 l stirred tank was charged with 400 g rapeseed oil raffinate, 333 g methanol and 40 g catalyst according to Example 1.
• the stirred tank was heated to 200 ° C. with stirring.
• the stirring speed was 1000 rpm.
• the rapeseed oil methyl ester fraction in the oil phase was 90.3% by weight.
• the proportion was determined according to DIN EN 14103. This results in an activity of
• the metal content in the rapeseed oil methyl ester phase was determined by means of ICP-OES (Perkin Elmer, Optima 3300 XL) according to DIN EN ISO 11885, after the rapeseed oil methyl ester phase had been converted into a water-soluble form by means of microwave digestion (DIN EN 14084).
• the concentrations of all catalyst metals (La, Al, Mg) in the rapeseed oil methyl ester phase were less than 1 ppm.
• the catalyst according to Example 1 surprisingly has a high activity and at the same time no leaching.

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