Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
  • C07C29/16—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by oxo-reaction combined with reduction
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
  • C07C29/132—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of an oxygen containing functional group
  • C07C29/136—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of an oxygen containing functional group of >C=O containing groups, e.g. —COOH
  • C07C29/147—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of an oxygen containing functional group of >C=O containing groups, e.g. —COOH of carboxylic acids or derivatives thereof
  • C07C29/149—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of an oxygen containing functional group of >C=O containing groups, e.g. —COOH of carboxylic acids or derivatives thereof with hydrogen or hydrogen-containing gases
• • 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
  • B01J35/40—Catalysts, in general, characterised by their form or physical properties characterised by dimensions, e.g. grain size
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C17/00—Preparation of halogenated hydrocarbons
  • C07C17/093—Preparation of halogenated hydrocarbons by replacement by halogens
  • C07C17/15—Preparation of halogenated hydrocarbons by replacement by halogens with oxygen as auxiliary reagent, e.g. oxychlorination
  • C07C17/152—Preparation of halogenated hydrocarbons by replacement by halogens with oxygen as auxiliary reagent, e.g. oxychlorination of hydrocarbons
  • C07C17/156—Preparation of halogenated hydrocarbons by replacement by halogens with oxygen as auxiliary reagent, e.g. oxychlorination of hydrocarbons of unsaturated hydrocarbons
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
  • C07C29/17—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by hydrogenation of carbon-to-carbon double or triple bonds
  • C07C29/177—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by hydrogenation of carbon-to-carbon double or triple bonds with simultaneous reduction of a carboxy group
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
  • C07C29/74—Separation; Purification; Use of additives, e.g. for stabilisation
  • C07C29/76—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment
  • C07C29/80—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment by distillation

Definitions

• the present invention relates to a process for the preparation of fatty alcohols which comprises providing a stream containing at least one fatty acid triglyceride and subjecting that stream to hydrogenation in the presence of a copper-containing, heterogeneous catalyst.
• Fatty alcohols are important intermediates for a variety of chemical products, such as.
• surfactants and cosmetic products They can be prepared, for example, by hydrogenation of fatty acid methyl esters which are obtainable from fatty or oleaginous starting products by transesterification of the triglycerides present.
• Glycerol which can be subjected, for example, to hydrogenation to give 1,2-propanediol, is obtained as further desired product.
• fatty alcohols by direct hydrogenation of triglyceride-containing starting materials, eg. B. of natural oils and fats to produce.
• DE-AS 1 154 448 describes a process for the preparation of higher molecular weight monohydric and polyhydric alcohols by catalytic hydrogenation of fats, fatty acids and fatty acid esters using tabletted copper-zinc, copper-chromium, copper-manganese, copper-zinc Chromium, copper-manganese-chromium, copper-cadmium, copper-cadmium-chromium and copper-cadmium-manganese catalysts.
• EP 0 063 427 A2 describes a process for the selective hydrogenation of unsaturated fatty acid derivatives in the presence of ammonia and a catalyst comprising at least one metal selected from Pd, Pt, Ir and Rh.
• EP 0 254 189 A2 describes a process for the direct hydrogenation of glyceride oils in the presence of catalysts comprising 30 to 40% by weight of copper, 23 to 30% by weight of chromium, 1 to 7% by weight of barium, in each case based on oxidic Catalyst mass, and, if desired, further transition metals in the form of their oxides.
• DE 37 08 430 A1 describes a process for the direct hydrogenation of butterfat in the presence of catalysts containing 30 to 40 wt .-% copper, 23 to 30 wt .-% chromium, 1 to 10 wt .-% manganese, 1 to 10 wt % Silicon and 1 to 7 wt .-% Ba- rium, each based on oxidic catalyst composition, and, if desired, further transition metals in the form of their oxides.
• DE 41 29 622 A1 describes a process for the preparation of unsaturated fatty alcohols by hydrogenation on a zinc-chromium catalyst of the spinel type.
• DE 198 43 798 A1 describes a process for the preparation of fatty alcohols by hydrogenating fatty acids or fatty acid esters on a fixed catalyst bed, in which unreacted hydrogen is recovered and recycled to the hydrogenation and the reactor is cooled by gassing with unheated hydrogen.
• WO 01/43873 A2 describes oxidic zinc-aluminum catalysts for the preparation of unsaturated fatty alcohols by hydrogenating unsaturated fatty acids, fatty acid lower alkyl esters or fatty acid glycerides.
• US 2004/0133049 A1 describes a process for the preparation of fatty alcohols from fatty acids, fatty acid esters and naturally occurring triglycerides in a fixed bed reactor.
• Suitable hydrogenation catalysts u. a. described oxidic copper-aluminum catalysts.
• WO 96/14280 describes a process for the direct hydrogenation of carboxylic acid esters to fatty alcohols in the presence of a catalyst comprising a copper compound, a zinc compound and at least one compound selected from compounds of aluminum, zirconium, magnesium, rare earth metals and mixtures thereof, includes.
• DE 42 42 466 A1 describes a process for the preparation of fatty alcohols, in which hydrogenated natural fats and oils in the presence of optionally calcined copper-zinc catalysts at a high hydrogen pressure and high temperature in a continuously operated tube bundle reactor.
• the present invention is based on the object to provide an improved process for the preparation of fatty alcohols available.
• the known methods are still in need of improvement in terms of the most complete hydraulic ration of fatty acid triglycerides at the same time good selectivity to 1, 2-propanediol as another product of value.
• the process provided should be particularly suitable for processing fatty acid triglyceride streams from biogenic sources as well as technically produced fatty acid triglyceride streams.
• copper-containing, heterogeneous catalysts wherein the catalytically active component of the catalyst additionally contains aluminum and at least one other metal selected from lanthanum, tungsten, molybdenum, titanium, zirconium and mixtures thereof, particularly advantageous for single-stage hydrogenation of Fatty acid triglyceride streams are suitable for obtaining fatty alcohols.
• these catalysts enable essentially complete single-stage hydrogenation.
• these catalysts are also characterized by a high selectivity to 1, 2-propanediol as a further product of value of the hydrogenation.
• the invention therefore provides a process for the preparation of fatty alcohols, in which
• a) provides a stream containing at least one fatty acid triglyceride
• the catalytically active component of the catalyst additionally contains aluminum and at least one further metal selected from lanthanum, tungsten, molybdenum, titanium, zirconium and mixtures thereof .
• step c) isolated from the hydrogenation product obtained in step b) at least one fatty alcohol-containing fraction.
• fatty alcohol in the context of the invention denotes saturated and unsaturated alcohols having 6 to 40, preferably 8 to 30, in particular 10 to 28 carbon atoms. These are, in particular, linear alcohols.
• they are saturated fatty alcohols or fatty alcohol mixtures which have predominantly saturated fatty alcohols (that is to say at least 80%).
• the process according to the invention enables a one-stage (ie direct) hydrogenation of a starting material containing fatty acid triglycerides to give a fatty alcohol-containing starting material. gene product.
• a one-stage it is understood that the fatty acid triglyceride-containing starting material without prior transesterification of the fatty acid triglycerides, eg. B. to fatty acid methyl esters, is used for hydrogenation.
• the inventive method also allows the hydrogenation of a fatty acid triglyceride-containing starting material without prior implementation to increase the content of free fatty acids.
• hydrogenation by the process according to the invention can be carried out in at least two hydrogenation reactors connected in series. In this embodiment, however, the isolation of partially hydrogenated intermediates is usually omitted.
• Oils and fats are generally solid, semi-solid or liquid fatty acid triglycerides, especially from vegetable and animal sources, which consist essentially of glycerolates of higher fatty acids.
• Suitable higher fatty acids are saturated or mono- or polyunsaturated fatty acids having preferably 6 to 40, particularly preferably 8 to 30, in particular 10 to 28 carbon atoms. These include z. B.
• n-nonanoic acid n-decanoic acid, n-undecanoic acid, n-tridecanoic, myristic, pentadecanoic, palmitic, margaric, nonadecanoic, arachidic, behenic, lignoceric, cerotic, melissic, palmitoleic, oleic, linoleic, linolenic, stearic, elaostearic, Etc.
• Vegetable fats and oils are based essentially on straight-chain fatty acids, whereas animal fats and oils may also contain odd-carbon fatty acids in a triglyceride-bound form.
• the unsaturated fatty acids found in vegetable fats and oils are in the cis form, while animal fatty acids are often trans-configured.
• fatty acid triglyceride-containing stream in step a) it is possible in principle to use used or unused, unpurified or purified vegetable, animal or industrial oils or fats or mixtures thereof. These parts of other ingredients, eg. As free fatty acids.
• the proportion of free fatty acids is generally 0% to 20%, z. B. 0.1 to 15%, based on the total weight of provided in step a) fatty acid triglyceride-containing stream.
• free fatty acids may, if desired, be partially or completely removed.
• Salts of these fatty acids may be previously purified by acidification with a strong acid, e.g. As HCl, are transferred to the free acid.
• a strong acid e.g. As HCl
• the separation of the free fatty acids succeed z. B. by centrifugation.
• suitable unused fats and oils are fatty or oleaginous components which, after their recovery from the corresponding vegetable or animal starting materials, have not yet been put to another purpose and which therefore contain only ingredients derived from the starting materials or related to the extraction from the starting materials. If desired, other ingredients than fatty acid triglycerides (and optionally free fatty acids) may be at least partially removed from these starting materials prior to use for the hydrogenation in step b).
• suitable used fats and oils are fat and / or oil-containing components, which after their extraction from corresponding biogenic starting materials for other purposes, eg. As for technical purposes or purposes of food production, have been used and which are chemically modified or unmodified as a result of this use or additional ingredients that are particularly related to this use may have. If desired, these may be at least partially removed to provide the fatty acid triglyceride-containing stream.
• the unused or used fats or oils may be subjected to the removal of undesired ingredients such as lecithin, carbohydrates, proteins, oil sludge, water, etc.
• Vegetable oils and fats are those derived predominantly from plant sources such as seeds, roots, leaves or other suitable parts of plants.
• Animal fats or oils are predominantly derived from animal feedstocks such as animal organs, tissues or other body parts or body fluids such as milk.
• Technical oils and fats are those obtained in particular from animal or vegetable raw materials and processed for technical purposes.
• the used or unused, unrefined or purified oils and / or fats used according to the invention are in particular selected from the group consisting of soapstock, Brown Grease, Yellow Grease, Technical Tallow, Technical Lard, Frying Oils, Animal Fat, Dairy Grease, Vegetable Crude Oils, Animal Crude Oils or Fats, or Mixtures thereof.
• Soapstock is understood to mean a by-product obtained in the processing of vegetable oils, in particular a by-product of edible oil refineries based on soybean, rapeseed or sunflower oil. Soapstock has a content of free fatty acids of about 50% to 80%.
• Brown Grease an animal fat-containing waste product having a content of free fatty acids of more than 15% to 40%.
• Yellow Grease contains about 5% to 15% free fatty acids.
• “Technical tallow” and “technical lard” are animal fats that are produced for technical purposes and are obtained, for example, from slaughterhouse waste by the dry or wet-melt process.
• Technical Tallow are evaluated and traded according to their acid number, the content of free fatty acids depending on the origin z. B. between 1 and 20 wt .-%, such as in the range of 1 to 15 wt .-%, is located. However, the content of free fatty acids may be more than 20 wt .-%.
• the "animal fats” include in particular in the utilization of poultry, beef, pork, fish and marine mammal bodies sloping fatty products, such as solar stearin, a solid residue remaining after pressing lard oil from lard.
• the provision of the fatty acid triglyceride-containing stream in step a) is preferably carried out from vegetable crude oils as starting material.
• This can be based on unrefined vegetable crude oils, ie of liquid or solid compositions which consist of vegetable starting materials, for. B. are obtained by pressing, where they have experienced no other treatment than settling in common periods and centrifuging or filtering, are used in the separation of the oil from solid components only mechanical forces such as gravity, centrifugal force or pressure.
• Such unrefined vegetable crude oils may also be obtained by extraction of vegetable oils, if their properties are not or only slightly different from the corresponding obtained by pressing vegetable oils.
• the proportion of free fatty acids in unrefined vegetable fats and oils is different and is z. B.
• the vegetable oils may be subjected to one or more work-up steps before they are used for the hydrogenation in step b), as they are described in more detail below.
• purified vegetable oils for example, raffinates or semi-refined, of the abovementioned vegetable oils can also be used as starting materials.
• a vegetable oil or fat is used, which is preferably selected from rapeseed oil, palm oil, rapeseed oil, soybean oil, sunflower oil, corn oil, cottonseed oil, palm kernel and coconut fat and mixtures thereof. Particular preference is given to using rapeseed oil or a rapeseed oil-containing mixture.
• Suitable for providing the fatty acid triglyceride-containing stream in step a) is also animal oil or fat, which is preferably selected from milk fat, wool fat, beef tallow, lard, fish oils, fish oil, etc., and mixtures thereof.
• the fatty acid triglyceride-containing stream provided in step a) preferably has a water content of at most 30% by weight, preferably of at most 20% by weight.
• a fatty acid triglyceride-containing stream is provided, which is essentially anhydrous.
• substantially anhydrous in the context of the present invention, a water content of at most 3 wt .-%, particularly preferably at most 1 wt .-% understood.
• fatty acid triglyceride-containing streams having a water content in the range of up to 30% by weight, in particular up to 20% by weight, makes it possible to prepare fatty alcohols and 1,2-propanediol in the temperature and pressure range used for the hydrogenation in step b) in high yields and with high selectivity.
• the fatty acid triglyceride-containing streams may comprise at least one organic solvent instead of or in addition to water.
• the fatty acid triglyceride-containing streams provided in step a) preferably have a total solvent content of at most 20% by weight, more preferably at most 15% by weight, in particular at most 10% by weight and especially at most 5% by weight. If solvent mixtures containing water and at least one water-miscible organic solvent are used, the proportion of the organic solvent is preferably at most 50% by weight, particularly preferably at most 20% by weight, based on the total weight of the solvent.
• Preferred organic solvents are C 1 -C 4 -alkanols, such as methanol, ethanol, n-propanol, isopropanol, n-butanol, tert-butanol, polyols and mono- and dialkyl ethers thereof, cyclic see ethers, such as dioxane and tetrahydrofuran, etc. Suitable solvents are also aromatic hydrocarbons, such as benzene, toluene or the XyIoIe. Preferred organic solvents are C 1 -C 4 -alkanols, in particular methanol and / or ethanol, and mixtures thereof with water.
• the fatty acid triglyceride-containing streams provided in step a) and used for the hydrogenation in step b) preferably have no organic solvents.
• the fatty acid triglyceride-containing streams provided in step a) may be subjected to at least one work-up step.
• the provision of the fatty acid triglyceride-containing stream in step a) comprises, in a specific embodiment, at least one purification step.
• a fat and / or oil-containing starting mixture at least one commonly used cleaning method for fats and oils, such as clarification, filtration, treatment with bleaching earths or treatment with acids or alkali to remove interfering impurities such as proteins, phosphatides and mucilage and a combination of at least two be subjected to these purification steps.
• the fatty acid triglyceride-containing streams may still contain inorganic salts as an undesired component. These can be removed by known work-up procedures.
• a thermal workup is suitable for this purpose (eg using an evaporator, for example, a Sambay evaporator).
• the fatty acid triglyceride-containing streams may also contain catalyst poisons, ie components which impair hydrogenation by deactivating the hydrogenation catalyst.
• catalyst poisons include z.
• nitrogen-containing compounds such as amines
• sulfur-containing compounds such as sulfuric acid, hydrogen sulfide, thio alcohols, thioethers, z.
• the catalyst poisons continue to include halogen compounds, traces of common extraction agents, eg. As acetonitrile or N-methylpyrrolidone, etc.
• z For working up the fatty acid triglyceride-containing streams in step a), z.
• a thermal work-up preferably a distillation, an adsorption, an ion exchange, a membrane separation process, a crystallization, an extraction or a combination of two or more of these processes can be used.
• Membrane separation processes using membranes of defined pore sizes are particularly suitable for reducing the water content and / or for salt removal. Crystallization is also understood to mean the partial freezing of the fatty acid triglyceride-containing streams on cooled surfaces.
• impurities can be removed, which accumulate in the solid phase.
• the fatty acid triglyceride-containing stream in step a) is subjected to distillation to reduce the water content and / or to remove components which impair the catalytic hydrogenation.
• this can be carried out by customary distillation methods known to the person skilled in the art.
• Suitable apparatus for working up by distillation include distillation columns, such as tray columns, which may be equipped with bells, sieve plates, sieve trays, packings, random packings, valves, side draws, etc., evaporators, such as thin film evaporators, falling film evaporators, forced circulation evaporators, Sambay evaporators, etc., and combinations from that.
• the fatty acid triglyceride-containing stream in step a) to reduce the content of sulfur-containing compounds, especially sulfur-containing aromatic compounds, a catalytic desulfurization, optionally in the presence of hydrogen subjected a desulfurizing agents include a metal component, which metal is preferably selected from metals of Groups 6, 7, 8, 9, 10, 11 and 12 of the Periodic Table.
• the metals are selected from Mo, Ni, Cu, Ag, Zn, and combinations thereof.
• Suitable further components of the desulfurization agents are dopants.
• the metal component can be used in oxidic form, reduced form or a mixture containing oxidized and reduced components.
• the active component of the desulfurizing agent can be applied to a support.
• Suitable carriers are in principle the adsorbents and catalyst carriers mentioned below.
• the support material is preferably selected from activated carbon, graphite, carbon black, Al 2 O 3, SiO 2, TiO 2, ZrO 2, SiC, silicates, zeolites, clays (for example bentonites) and combinations thereof.
• the application of at least one metal component and optionally further components to a carrier material can be carried out by known methods, for. By (Co) precipitation or impregnation.
• the desulfurizing agent can be used as a shaped body, for.
• Unsupported desulfurizing agents can be molded by conventional methods, e.g. By extruding, tableting, etc.
• the shape of the supported desulfurizing agent is determined by the shape of the carrier.
• a desulphurising agent which comprises 35 to 45% by weight of copper oxide, 35 to 45% by weight of zinc oxide and 10 to 30% by weight of aluminum oxide.
• the desulfurizing agent is a component capable of being used as a hydrogenation catalyst in step b).
• the fatty acid triglyceride-containing streams are brought into contact with the desulfurizing agent in at least one desulfurization zone and subsequently hydrogenated in at least one reaction zone.
• the specific design and arrangement of the desulfurization and reaction zone (s) may be in any known manner. It is possible to arrange the desulfurization and reaction zone (s) spatially separated, i. H. structurally separate from one another by means of the apparatus configuration or also to be realized in one or more common desulfurization / hydrogenation zone (s).
• the copper-zinc desulfurizing agent may, for. B. obtained by a conventional precipitation or co-precipitation and used in oxidized as well as in reduced form.
• the copper-zinc desulfurizing agent contains at least copper, zinc and aluminum, wherein the copper: zinc: aluminum atomic ratio ranges from 1: 0.3: 0.05 to 1: 10: 2, preferably 1: 0.6: 0.3 to 1: 3: 1 and especially 1: 0.7: 0.5 to 1: 1, 5: 0.9.
• the desulfurizing agent For conversion to the reduced form, it is possible to subject the desulfurizing agent to a hydrogen reduction. This is carried out at about 150 to 350 0 C, preferably at about 150 to 250 0 C, in the presence of hydrogen, wherein the hydrogen by an inert gas such. As nitrogen, argon, methane, in particular nitrogen, is diluted, so that the hydrogen content is 10 vol .-% or less, preferably 6 vol .-% or less, in particular 0.5 to 4 vol .-%, is.
• the resulting copper-zinc desulfurizing agent ("reduced form") can be used in this form in the desulfurization.
• the desulfurization of the fatty acid triglyceride-containing stream is carried out on the copper-zinc desulfurizing agent in oxidized form without the addition of hydrogen.
• the desulfurization of the fatty acid triglyceride-containing stream is carried out on the copper-zinc desulfurizing agent in oxidized form in the presence of hydrogen.
• the desulfurization of the fatty acid triglyceride-containing stream is carried out on the copper-zinc desulfurizing agent in reduced form without the addition of hydrogen.
• the desulfurization of the fatty acid triglyceride-containing stream on the copper-zinc desulfurizing agent is carried out in reduced form in the presence of hydrogen.
• the desulfurization can in the presence of inert gases such. As nitrogen, argon or methane, are performed. In general, however, the desulfurization is carried out without the addition of inert gases.
• inert gases such as nitrogen, argon or methane
• hydrogen is used here with a purity of ⁇ 99.8% by volume, in particular 99.9% by volume, preferably 99.95% by volume. These degrees of purity apply analogously to the hydrogen which is used in the optionally carried out activations of the catalysts.
• the weight ratio of fatty acid triglyceride-containing stream to hydrogen is in the range from 40,000: 1 to 1,000: 1, especially in the range from 38,000: 1 to 5000: 1, in particular in the range from 37,000: 1 to 15,000: 1, preferably in the range from 36,000: 1 to 25,000: 1, especially in the range of 35,000: 1 to 30,000: 1.
• the thus-desulphurised fatty acid triglyceride-containing stream generally has a content of sulfur-containing impurities, especially of aromatic sulfur compounds, of at most 70 ppb, preferably of at most 50 ppb, and the total sulfur content is ⁇ 200 ppb, preferably ⁇ 150 ppb, especially ⁇ 100 ppb.
• the above-described desulfurizing agents also make it possible to reduce or remove chlorine, arsenic and / or phosphorus or corresponding chlorine-, arsenic- and / or phosphorus-containing compounds from the fatty acid triglyceride-containing compound.
• the fatty acid triglyceride-containing stream is contacted with at least one adsorbent in step a) to remove components which interfere with the catalytic hydrogenation.
• the adsorbents preferably have a specific surface area, determined by BET, in the range from 10 to 2000 m 2 / g, more preferably in the range from 10 to 1500 m 2 / g, in particular in the range from 10 to 400 m 2 / g, especially in Range from 60 to 250 m 2 / g.
• Suitable adsorbents are z. B. active aluminas. Their preparation takes place for. B. starting from aluminum hydroxide, which is obtainable by conventional precipitation of aluminum salt solutions. Active aluminas suitable for the process according to the invention are also obtainable starting from aluminum hydroxide gels. For the preparation of such gels z. Example, precipitated aluminum hydroxide after conventional work-up steps, such as filtering, washing and drying, activated and then optionally ground or agglomerated. If desired, the resulting alumina can then be subjected to a shaping process. application process, such as extrusion, granulation, tabletting, etc. subject. Suitable adsorbents are preferably the Selexsorb TM types from Alcoa.
• Suitable adsorbents are also alumina-containing solids. These include z. As the so-called clays, which also have aluminum oxides as the main component.
• adsorbents are aluminum phosphates.
• adsorbents are silicas, the z. B. by dehydration and activation of silica gels are available.
• Another method for producing silica is the flame hydrolysis of silicon tetrachloride, wherein by suitable variations of the reaction parameters, such. As the stoichiometric composition of the educt mixture and the temperature, the desired surface properties of the resulting silica can be varied within wide ranges.
• adsorbents are diatomaceous earth, which also have silicas as their main constituent. This includes z.
• the diatomaceous earth obtained from silica sediments.
• adsorbents are titanium dioxides and zirconium dioxides, as z. In Römpp, Chemie-Lexikon, 9th edition (paperback), Vol. 6, p. 4629f. and pp. 5156f. and the literature cited therein. This is hereby fully incorporated by reference.
• adsorbents are phosphates, in particular condensed phosphates, such as. As melting or annealing phosphates, which have a large active surface area.
• Suitable phosphates are, for. In Römpp, Chemie-Lexikon, 9th Edition (Pabback), Vol. 4, p. 3376f. and the literature cited therein. This is hereby fully incorporated by reference.
• adsorbents are carbonaceous adsorbents, preferably activated carbon.
• Activated carbon is generally understood to mean carbon with a porous structure and a high internal surface area.
• plant, animal and / or mineral carbonaceous raw materials eg. B. with dehydrating agents such as zinc chloride or phosphoric acid, heated or charred by dry distillation and then activated by oxidation. You can do that z. B. treat the charred material at elevated temperatures of about 700 to 1000 0 C with water vapor, carbon dioxide and / or mixtures thereof.
• the adsorbents are preferably selected from titanium dioxides, zirconium dioxides, silicium dioxides, kieselguhr, aluminum oxides, aluminum oxide-containing solids, aluminum phosphates, natural and synthetic aluminum silicates, phosphates, carbonaceous adsorbents and mixtures thereof.
• the adsorbents generally have a specific surface area, determined by BET, in the range of about 10 to 2000 m 2 / g, in particular in the range of 10 to 1500 m 2 / g and especially in the range of 20 to 600 m 2 / g ,
• the fatty acid-containing triglyceride-containing stream in step a) is brought into contact with at least one adsorption agent in an adsorption zone.
• an adsorbent which contains at least one component which is also capable of being used as hydrogenation catalyst in step b).
• the hydrogenation catalysts described in more detail below are hereby incorporated by reference in their entirety.
• Combinations of two or more than two adsorption centers are also suitable for use as adsorbents. In this case, both exclusively as hydrogenation catalysts capable components, not suitable as hydrogenation adsorbents and combinations thereof are used exclusively.
• the same component is used as the adsorbent and as the hydrogenation catalyst. If appropriate, one additionally uses one or more further conventional adsorbents other than the hydrogenation catalyst, as described above.
• the fatty acid triglyceride-containing streams are brought into contact with the adsorbent in at least one adsorption zone and then hydrogenated in at least one reaction zone.
• adsorption and reaction zone (s) may be in any known manner. It is preferred to arrange the adsorption and reaction zone (s) spatially separated from each other, ie to separate structurally from one another by the apparatus design.
• z. B a first adsorption zone in a first reactor, which contains a first adsorbent, and separately, so separated by equipment, z. B. in a second reactor, a second adsorption zone containing a second adsorbent.
• the first and / or the second adsorbent may contain at least one component capable of being used as a hydrogenation catalyst.
• a conventional adsorbent is used together with an adsorbent capable of hydrogenation in a single adsorption zone, e.g. B. in layered form, mixed in the form of a random distribution or in the form of a gradient bed.
• the use in mixed form optionally allows better control of the temperature.
• a gradient bed linear and non-linear gradients can be used. It may be advantageous in this case to carry out the distribution within the bed in such a way that the fatty acid triglyceride-containing stream to be hydrogenated is first brought into contact with the conventional adsorbent before it is brought into contact with the adsorbent capable of hydrogenation.
• At least two adsorption zones will be arranged so that the fatty acid triglyceride-containing stream to be hydrogenated in the first adsorption zone is contacted with a conventional adsorbent and contacted in the second adsorption zone with an adsorbent containing at least one component capable of use as a hydrogenation catalyst becomes.
• a heterogeneous catalyst which contains copper, aluminum and at least one further metal selected from lanthanum, tungsten, molybdenum, titanium, zirconium and mixtures thereof.
• the heterogeneous hydrogenation catalysts used in the process according to the invention may be unsupported catalysts or supported catalysts. They may take the form of uniformly composed catalysts, impregnated catalysts, coated catalysts and precipitation catalysts are used.
• Suitable catalysts may include the metals in oxidic form, reduced form (elemental form) or a combination thereof. Metals that are stable in more than one oxidation state can be used completely in one of the oxidation states or in different oxidation states.
• a special embodiment of catalysts which are particularly advantageous for use in the process according to the invention are catalysts which contain copper in oxidic form and optionally additionally in elemental form.
• the hydrogenation catalyst used in step b) then preferably contains at least 25% by weight, particularly preferably at least 35% by weight, of copper in oxidic and / or elemental form, based on the total weight of the catalyst.
• catalysts include the following metals: Cu, Al, La or Cu, Al, W.
• a frequently used process for the preparation of such catalysts consists in the impregnation of support materials with solutions of the catalyst components, which are then converted by thermal treatment, decomposition or reduction in the catalytic active state.
• Another suitable method for the preparation of catalysts comprises the precipitation of at least one catalyst component.
• Various catalyst components may be sequentially precipitated, or two or more than two catalyst components may be precipitated in a co-precipitation.
• a copper compound, at least one further metal compound and optionally at least one additive can be precipitated and then subjected to drying, calcining and shaping.
• the precipitation can be carried out in the presence of a carrier material.
• Suitable starting materials for the precipitation are metal salts and metal complexes. In principle, all known metal salts which are soluble in the solvents used for application to the carrier can be used as metal compounds for the precipitation. These include z.
• nitrates carbonates, acetates, oxalates or ammonium complexes.
• at least one metal nitrate is used.
• an aqueous medium is used for the precipitation.
• Suitable aqueous media are substances or mixtures which are liquid under the process conditions and which contain at least 10% by weight, particularly preferably at least 30% by weight, in particular at least 50% by weight, of water.
• the portion other than water is preferably selected from inorganic or organic compounds which are at least partially soluble in water or at least partially miscible with water.
• the compounds other than water are selected from organic solvents, such as C 1 -C 20 -alkanols, in particular methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, tert-butanol, penthanols and hexanols, C 8 -cycloalkyl ethers, such as tetrahydrofurans, pyrans, dioxanes and trioxanes, C 1 -C 12 -dialkyl ethers, such as dimethyl ether, dibutyl ether and methyl butyl ether.
• the aqueous medium preferably contains less than 40% by weight, more preferably less than 30% by weight and in particular less than 20% by weight of organic solvents. In a preferred embodiment of the process according to the invention, the aqueous medium is substantially free of organic solvents.
• the precipitation may be carried out by known methods, e.g. B. cooling a saturated solution, adding a precipitant, etc. induced. Suitable precipitants are for. As acids, bases, reducing agents, etc.
• the precipitate may be induced by adding an acid or a base to the aqueous medium containing the copper compound and optionally further compounds.
• Suitable acids are mineral acids such as HCl, H2SO4 and H3PO4.
• the base is preferably selected from metal oxides, metal hydroxides, in particular alkali metal hydroxides, such as sodium hydroxide and potassium hydroxide, metal carbonates, in particular alkali metal and alkaline earth metal carbonates, such as lithium carbonate, sodium carbonate, potassium carbonate, magnesium carbonate and calcium carbonate, nitrogen bases, especially ammonia and primary, secondary and tertiary amines.
• suitable reducing agents are carboxylic acids, such as formic acid, citric acid, lactic acid, tartaric acid and, in particular, salts of carboxylic acids, preferably the alkali metal, alkaline earth metal, ammonium and C 1 -C 10 -alkylammonium salts, phosphorous or hypophosphorous acid, the salts of phosphorous or hypophosphorous Acid, in particular the alkali metal or alkaline earth metal salts, C 1 -C 10 -alkanols, such as methanol, ethanol and isopropanol, sugars, such as aldoses and ketoses in the form of monosaccharides, disaccharides and oligosaccharides, in particular glucose, fructose and lactose, aldehydes, such as formaldehyde, boron Hydrogen compounds such as borohydrides, boranes, metal borohydrides and borane complexes, such as diborane, sodium borohydride and aminobora
• WO 2006/005505 describes shaped catalyst bodies which are particularly suitable for use in the process according to the invention. These can be produced by a process in which
• an oxidic material comprising copper oxide, alumina and at least one of the oxides of lanthanum, tungsten, molybdenum, titanium or zirconium, wherein the oxides of lanthanum and / or tungsten are to be preferred, is provided,
• powdered metallic copper, copper flakes, powdered cement or mixtures thereof or a mixture thereof with graphite may be added to the oxidic material, and
• lanthanum oxide is preferred.
• the composition of the oxide material is generally such that the proportion of copper oxide in the range of 40 to 90 wt .-%, the proportion of oxides of lanthanum, tungsten, molybdenum, titanium or zirconium in the range of 1 to 59 wt.
• the oxide material comprises
• the hydrogenation catalyst used in step b) is preferably a catalyst comprising or consisting of an oxidic material of the composition (CuO) o, 6-o, 8 (Al 2 O 3) o, io, 34 (La 2 O 3) o, o 2 -o, 2 such oxidic material.
• a particularly suitable catalyst has the chemical composition 57% CuO, 28.5% Al 2 O 3 , 9.5% La 2 O 3 and 5% Cu.
• support material for the catalysts of the invention, virtually all support materials of the prior art, as they are advantageously used in the preparation of supported catalysts, for example SiO 2 (quartz), porcelain, magnesium oxide, tin dioxide, silicon carbide, TiO 2 (rutile, anatase) , Al 2 O 3 (alumina), aluminum silicate, steatite (magnesium silicate), zirconium silicate, cersilicate or mixtures of these support materials.
• Preferred support materials are alumina and silica.
• silicon dioxide carrier material can SiIi- ciumdioxid materials of different origin and production, for. B.
• pyrogenic silicas or wet-chemically prepared silicas such as silica gels, aerogels or precipitated silicas, are used for catalyst preparation (for the preparation of various SiO 2 starting materials see: W. Büchner, R. Sch Kunststoffs, G. Winter, KH Büchel: Industrial Inorganic Chemistry ; 2nd ed., P. 532-533, VCH Verlagsgesellschaft, Weinheim 1986).
• the catalysts can be used as shaped bodies, for. B. in the form of spheres, rings, cylinders, cubes, cuboids or other geometric bodies.
• Unsupported catalysts can be formed by conventional methods, e.g. By extruding, tableting, etc.
• the shape of supported catalysts is determined by the shape of the support.
• the support may be subjected to a molding process before or after application of the catalytically active component (s).
• the catalysts may, for. In the form of pressed cylinders, tablets, pastilles, carriage wheels, rings, stars or extrudates, such as Solid strands, polylobd strands, hollow strands and honeycomb bodies or other geometric bodies are used.
• the catalyst particles generally have an average of the (largest) diameter of 0.5 to 20 mm, preferably 1 to 10 mm.
• These include z. B. catalysts in the form of tablets, for. B. with a diameter of 1 to 7 mm, preferably 2 to 6 mm, and a height of 3 to 5 mm, rings with z. B. 4 to 7 mm, preferably 5 to 7 mm, outer diameter, 2 to 5 mm in height and 2 to 3 mm hole diameter, or strands of different lengths of a diameter of z. B. 1, 0 to 5 mm.
• Such forms can be obtained in a manner known per se by tableting, extrusion or extrusion.
• the catalyst composition customary auxiliaries, for.
• lubricants such as graphite, polyethylene oxide, celluloses or fatty acids (such as stearic acid), and / or molding aids and reinforcing agents, such as fibers of glass, asbestos or silicon carbide, are added.
• a specific embodiment of supported catalysts are shell catalysts.
• Shelled catalysts comprise a cup-shaped catalytic mass applied to a carrier. They can be in the form of spheres, rings, cylinders, cubes, cuboids or other geometric bodies.
• the provision of coated catalyst particles can in principle be accomplished by contacting the support with a liquid binder and the catalytically active composition, thereby applying a layer of the composition to the support, and then optionally the binder partially removed.
• the catalytically active material is already applied in its finished catalytically active form, for example as a calcined mixed oxide. Suitable processes for the preparation of coated catalysts are, for.
• the carrier is first moistened with the liquid binder, then adhered by contacting with dry, finely divided, active catalyst mass on the surface of the moistened carrier body, a layer of active catalyst mass and then optionally partially removed the liquid binder.
• the steps of wetting the carrier, contacting the catalyst mass and removing the liquid binder are repeated one or more times until the desired layer thickness of the coated catalyst is reached.
• supported catalysts are catalysts prepared by impregnation.
• the catalytically active catalyst components or precursor compounds thereof can be applied to the carrier material. be gene.
• aqueous salt solutions of the components for.
• aqueous solutions of their halides, sulfates, nitrates, etc. applied.
• the copper component may, for. Example, in the form of an aqueous solution of their amine complex salts, for example as [Cu (NH 4 ) 4 ] SO 4 - or as [Cu (NH 3 ) 4 ] (N ⁇ 3) 2 solution, optionally in the presence of sodium carbonate, on the support material be applied.
• other copper amine complexes than those exemplified may be used with equal success for catalyst preparation.
• the impregnation of the carrier material with the precursor compounds of the catalytically active components can in principle be carried out in one or more stages.
• the impregnation can be carried out in conventional impregnating devices, e.g. Impregnated drums.
• the finished catalyst is then obtained.
• the drying of the impregnated catalyst moldings can be carried out continuously or batchwise, for. B. in band or Hordenöfen done.
• the drying can be carried out at atmospheric pressure or reduced pressure.
• the drying in a gas stream for. As an air stream or a stream of nitrogen, take place.
• the drying is generally carried out at temperatures of 50 to 200 0 C, preferably 80 to 150 0 C.
• the calcination of the optionally previously dried catalyst is generally carried out at temperatures of 200 to 800 0 C, preferably 500 to 700 0 C.
• the calcination like the drying, continuously or batchwise, for. B. in band or Hordenöfen performed.
• the calcination may be carried out at atmospheric or reduced pressure and / or in a gas stream, e.g. B. in an air or a hydrogen stream.
• Pre-treatment with hydrogen or hydrogen-containing gases generally under conditions which correspond to the hydrogenation conditions serves to pre-reduce / activate the hydrogenation catalyst.
• the catalyst can also be reduced in situ under the conditions prescribed in the hydrogenation, preferably under pressure (for example at a hydrogen pressure of about 100 to 325 bar).
• the hydrogenation in step b) is preferably carried out at a temperature in a range from 100 to 320 ° C., particularly preferably from 150 to 270 ° C., in particular from 180 to 230 ° C.
• the hydrogenation in step b) is preferably carried out at a pressure in a range from 100 to 325 bar, more preferably from 150 to 300 bar, in particular from 180 to 230 bar.
• the molar ratio of hydrogen to fatty acid triglyceride is preferably 10: 1 to 1000: 1, more preferably 12.5: 1 to 500: 1.
• the catalyst loading in continuous operation is preferably 0.1 to 1, more preferably 0.2 to 0.5 kg of fatty acid triglyceride to be hydrogenated / kg (catalyst) x h.
• the conversion, based on fatty acid triglyceride, is preferably at least 90%, in particular at least 95%.
• the selectivity in the hydrogenation in step b), with respect to propanediol 1, 2 (based on the sum of glycerol and hydrogenation products of glycerol), in the process according to the invention is preferably at least 85%, more preferably at least 90%. In many cases even higher selectivities of up to 95% and more can be achieved.
• the hydrogenation is preferably carried out continuously.
• the hydrogenation discharge consists essentially of fatty alcohols and propanediol-1, 2. Further constituents are selected from methanol, ethanol, n-propanol, isopropanol, propanediol-1, 3, glycerol, ethylene glycol and water.
• the hydrogenation is carried out in n hydrogenation reactors connected in series (in series), n being an integer of at least 2. Suitable values for n are 2, 3, 4, 5, 6, 7, 8, 9 and 10. Preferably, n is 3 to 6 and in particular 2 or 3. In this embodiment, the hydrogenation is preferably carried out continuously.
• the reactors used for the hydrogenation in step b) can independently of one another have one or more reaction zones within the reactor.
• the reactors may be the same or different reactors. These can be z. B. each have the same or different mixing characteristics and / or be subdivided by internals one or more times.
• Suitable pressure-resistant reactors for the hydrogenation are known to the person skilled in the art. These include the commonly used reactors for gas-liquid reactions, such as. B. tube reactors, tube bundle reactors, gas circulation reactors, bubble columns, loop apparatus, stirred tank (which can also be designed as stirred tank cascades), air-lift reactors, etc.
• the process according to the invention using heterogeneous catalysts can be carried out in fixed bed or suspension mode.
• the fixed bed mode can be z. B. in sump or in trickle run.
• the catalysts are preferably used as moldings, as described above, for. In the form of pressed cylinders, tablets, pastilles, carriage wheels, rings, stars or extrudates, such as solid strands, polylobal strands, hollow strands, honeycomb bodies, etc.
• heterogeneous catalysts are also used.
• the heterogeneous catalysts are usually used in a finely divided state and are finely suspended in the reaction medium before.
• Suitable heterogeneous catalysts and processes for their preparation are those described above.
• a reactor In the hydrogenation on a fixed bed, a reactor is used, in the interior of which a fixed bed is arranged, through which the reaction medium flows.
• the fixed bed can be formed from a single or multiple beds.
• Each bed may have one or more zones, wherein at least one of the zones contains a material active as a hydrogenation catalyst.
• Each zone can have one or more different catalytically active materials and / or one or more different inert materials. Different zones may each have the same or different compositions. It is also possible to provide a plurality of catalytically active zones, which are separated from each other, for example, by inert beds. The individual zones may also have different catalytic activity.
• reaction medium which flows through the fixed bed contains according to the invention at least one liquid phase.
• the reaction medium may also contain a gaseous phase in addition.
• loop apparatuses such as jet loops or propeller loops
• stirred tank which can also be configured as ROWkesselkaskaden, bubble columns or air-lift reactors are used.
• the continuous hydrogenation in step b) takes place in at least two fixed bed reactors connected in series (in series).
• the reactors are preferably operated in DC.
• the feeding of the feed streams can be done both from above and from below.
• the fatty acid triglyceride, the resulting fatty alcohols and the resulting 1,2-propanediol are preferably in the liquid phase.
• the conditions can be selected so that individual components of the reaction mixture taken by itself would be solid under these conditions. This applies z. b. for the fatty alcohol (s).
• the temperature in the hydrogenation in step b) is generally about 150 to 300 ° C., in particular 180 to 250 ° C., in all reactors.
• At least two of the reactors may have a different temperature from each other.
• each downstream reactor is operated at a higher temperature than the previous reactor.
• each of the reactors may have two or more different temperature reaction zones.
• another, preferably a higher, temperature than in the first reaction zone or in each subsequent reaction zone can be set to a higher temperature than in a preceding reaction zone, for. B. to achieve the fullest possible conversion in the hydrogenation.
• the reaction pressure in step b) is preferably in all reactors generally about 150 to 300 bar, more preferably 180 to 250 bar.
• At least two of the reactors may have a different pressure from each other.
• each downstream reactor is operated at a higher pressure than the previous reactor.
• the feeding of the hydrogen required for the hydrogenation can be carried out in the first and optionally additionally in at least one other Rector.
• the feed of hydrogen takes place only in the first reactor.
• the amount of hydrogen fed to the reactors results from the amount of hydrogen consumed in the hydrogenation reaction and the amount of hydrogen optionally discharged with the exhaust gas.
• the setting of the reacted in the respective reactor fatty acid triglyceride portion can, for. B. on the reactor volume and / or the residence time in the reactor.
• the conversion in the first reactor, based on fatty acid triglyceride is preferably at least 60%, more preferably at least 70%.
• the total conversion in step b), based on the fatty acid triglyceride is preferably at least 97%, particularly preferably at least 98%, in particular at least 99%.
• one or more of the reactors may be provided with at least one cooling device.
• at least the first reactor is provided with a cooling device.
• the heat of reaction can be removed by cooling an external recycle stream or by internal cooling in at least one of the reactors.
• the devices customary for this purpose generally hollow body modules, such as field tubes, tube coils, heat exchanger plates, etc., can be used.
• the reaction can also be carried out in a cooled tube bundle reactor.
• the hydrogenation in step b) is preferably carried out in n hydrogenation reactors connected in series, where n is an integer of at least two, and where at least one reactor has an external circulation stream from the reaction zone (external recycle stream, liquid recycle, loop). driving style).
• n stands for two or three.
• the hydrogenation in step b) preferably takes place in n hydrogenation reactors connected in series, where n is preferably two or three, and the first to (n-1). Reactor has a guided in an external circuit current from the reaction zone.
• the hydrogenation in step b) preferably takes place in n series-connected hydrogenation reactors, n preferably being two or three, and the reaction being carried out adiabatically in the nth reactor (the last reactor through which the reaction mixture to be hydrogenated).
• the hydrogenation in step b) preferably takes place in n series-connected hydrogenation reactors, n preferably being two or three, and the nth reactor being operated in a straight pass.
• the hydrogenated reaction mixture in one of the reactors connected downstream of the first reactor contains only so small amounts of hydrogenation having a fatty acid triglyceride such that the heat of reaction that occurs in the reaction is not sufficient to maintain the desired temperature in the reactor, it may also be necessary to heat the reactor (or individual reaction zones of the second reactor). This can be carried out analogously to the previously described removal of the heat of reaction by heating an external circulating flow or by internal heating.
• the heat of reaction from at least one of the previous reactors can be used to control the temperature of a reactor.
• the heat of reaction removed from the reaction mixture can be used to heat the feed streams of the reactors.
• This can z. B. the Fettklaretriglyceridzulaufstrom in the first reactor at least partially mixed with an external recycle stream of this reactor and the combined streams are then fed into the first reactor.
• the feed stream from the (m-1) th reactor in the mth reactor can be mixed with a recycle stream of the mth reactor and the combined streams then fed into the mth reactor
• the fatty acid triglyceride feed stream and / or another feed stream can be heated by means of a heat exchanger which is operated with withdrawn hydrogenation heat.
• a reactor cascade of n reactors connected in series is used, the reaction being carried out adiabatically in the nth (nth) reactor.
• This term is understood in the context of the present invention in the technical and not in the physico-chemical sense.
• the reaction mixture undergoes flow through the second reactor
• Adiabatic reaction is understood to mean a procedure in which the amount of heat liberated during the hydrogenation is taken up by the reaction mixture in the reactor and no cooling by cooling devices is used.
• the reaction heat is removed with the reaction mixture from the second reactor, except for a residual portion which is discharged by natural heat conduction and heat radiation from the reactor to the environment.
• the nth reactor is operated in a straight pass.
• a two-stage reactor cascade is used for the hydrogenation in step b), wherein the first hydrogenation reactor has a current in the reaction zone conducted in an external circuit.
• a reactor cascade is made up of two series connected Teten reactors used, wherein the reaction in the third reactor is carried out adiabatically.
• a three-stage reactor cascade is used for the hydrogenation in step b), wherein the first and the second hydrogenation reactor have a current in the reaction zone conducted in an external circuit.
• a reactor cascade of three reactors connected in series is used, the reaction being carried out adiabatically in the third reactor.
• additional mixing can take place in at least one of the reactors used. Additional mixing is particularly advantageous if the hydrogenation is carried out at high residence times of the reaction mixture.
• the currents introduced into the reactors are used by introducing them via suitable mixing devices, such as nozzles, in the respective reactors.
• suitable mixing devices such as nozzles, in the respective reactors.
• the discharge is separated into a first and a second partial stream, wherein the first partial stream is recirculated as a circulating stream to the reactor from which it was taken, and the second partial stream is fed to the downstream reactor.
• the discharge may contain dissolved or gaseous portions of hydrogen.
• the discharge from the first to (n-1) th reactor is fed to a phase separation vessel, separated into a liquid and into a gaseous phase, the liquid phase separated into the first and the second partial stream and the gas phase at least partially fed separately downstream reactor.
• the discharge from the first to (n-1) th reactor is fed to a phase separation vessel and separated into a first liquid hydrogen-depleted substream and a second hydrogen-enriched substream.
• the first partial stream is then recirculated to the reactor as a circulating stream, from which it has been taken off and the second partial stream is fed to the subsequent reactor (as a fatty acid triglyceride- and hydrogen-containing feed).
• the feed of the second to n-th reactor with hydrogen is not carried out via a hydrogen-containing feed taken from the upstream reactor, but with fresh hydrogen via a separate feed line.
• Another way to control the heat balance is to control the inlet temperature of the fatty acid triglyceride-containing feed.
• a lower temperature of the incoming feed usually leads to an improved removal of the heat of hydrogenation.
• the inlet temperature can be set higher to achieve a higher reaction rate and thus to compensate for decreasing catalyst activity.
• the service life of the catalyst used can be extended.
• the hydrogenation without being subjected to a work-up can be isolated as a fatty alcohol-containing fraction. This is the case if the remaining components do not adversely affect the intended use.
• the hydrogenation is subjected to a work-up by conventional methods known in the art.
• thermal processes preferably distillative processes, adsorption, ion exchange, membrane separation processes, crystallization, extraction or a combination of two or more of these processes are suitable for this purpose.
• the hydrogenation is worked up by distillation. Suitable for this purpose are customary distillation processes known to the person skilled in the art.
• Suitable apparatus for the work-up by distillation comprise distillation columns, such as tray columns, which may be provided with bells, sieve plates, sieve trays, packings, internals, valves, side draws, etc.
• dividing wall columns which can be provided with side draws, returns, etc.
• a combination of two or more than two distillation columns can be used.
• evaporators such as thin film evaporators, falling film evaporators, Sambay evaporators, etc., and combinations thereof.
• a stream containing 1,2-propanediol is additionally isolated from the product of the hydrogenation in step c).
• a rapeseed oil was used, which after saponification and analysis of
• Linoleic acid 24.2 area%
• the first reactor had a catalyst volume of 140 ml and the second reactor a catalyst volume of 100 ml.
• an oxidic material containing CuOo, 6-o, 85 (AbOs) O, 1-0.34 (La2 ⁇ 3) o, oi-o, 2 comprises used as catalyst (1st reactor: 182 g, 2nd reactor: 133 g). The catalyst was reduced in the hydrogen stream before the hydrogenation reaction.
• the first reactor had a circulation and was operated in trickle mode, the second reactor was operated in a straight pass.
• the continuous hydrogenation took place over 1400 hours.
• the temperature in the first reactor was at the reactor inlet 205 0 C and at the reactor outlet 220 0 C, the
• Temperature in the second reactor was constant 200 0 C.
• the hydrogen pressure was 200 bar in both reactors.
• the catalyst loading was adjusted to 0.18 kgR apS oi / Uat xh. Deactivation of the catalyst over the experimental period was not detected. Under the above conditions, a conversion of 97% and a yield of octadecanol of 85 wt .-% (98% of theory) was achieved.

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