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  • C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
  • C07C45/002—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by dehydrogenation
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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  • B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
  • B01J8/02—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds
  • B01J8/06—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds in tube reactors; the solid particles being arranged in tubes
  • B01J8/065—Feeding reactive fluids
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  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
  • B01J8/02—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds
  • B01J8/06—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds in tube reactors; the solid particles being arranged in tubes
  • B01J8/067—Heating or cooling the reactor
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  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen; Reversible storage of hydrogen
  • C01B3/02—Production of hydrogen; Production of gaseous mixtures containing hydrogen
  • C01B3/22—Production of hydrogen; Production of gaseous mixtures containing hydrogen by decomposition of gaseous or liquid organic compounds
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  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C1/00—Preparation of hydrocarbons from one or more compounds, none of them being a hydrocarbon
  • C07C1/20—Preparation of hydrocarbons from one or more compounds, none of them being a hydrocarbon starting from organic compounds containing only oxygen atoms as heteroatoms
  • C07C1/207—Preparation of hydrocarbons from one or more compounds, none of them being a hydrocarbon starting from organic compounds containing only oxygen atoms as heteroatoms from carbonyl compounds
  • C07C1/2076—Preparation of hydrocarbons from one or more compounds, none of them being a hydrocarbon starting from organic compounds containing only oxygen atoms as heteroatoms from carbonyl compounds by a transformation in which at least one -C(=O)- moiety is eliminated
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  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C11/00—Aliphatic unsaturated hydrocarbons
  • C07C11/12—Alkadienes
  • C07C11/16—Alkadienes with four carbon atoms
  • C07C11/167—1, 3-Butadiene
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  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C47/00—Compounds having —CHO groups
  • C07C47/02—Saturated compounds having —CHO groups bound to acyclic carbon atoms or to hydrogen
  • C07C47/06—Acetaldehyde
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  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C7/00—Purification; Separation; Use of additives
  • C07C7/005—Processes comprising at least two steps in series
• • 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
  • B01J2208/00—Processes carried out in the presence of solid particles; Reactors therefor
  • B01J2208/00008—Controlling the process
  • B01J2208/00017—Controlling the temperature
• • 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
  • B01J2208/00—Processes carried out in the presence of solid particles; Reactors therefor
  • B01J2208/00008—Controlling the process
  • B01J2208/00539—Pressure
• • 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
  • B01J2208/00—Processes carried out in the presence of solid particles; Reactors therefor
  • B01J2208/00008—Controlling the process
  • B01J2208/00548—Flow
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  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
  • C01B2203/02—Processes for making hydrogen or synthesis gas
  • C01B2203/0266—Processes for making hydrogen or synthesis gas containing a decomposition step
  • C01B2203/0277—Processes for making hydrogen or synthesis gas containing a decomposition step containing a catalytic decomposition step
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  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
  • C01B2203/08—Methods of heating or cooling
  • C01B2203/0805—Methods of heating the process for making hydrogen or synthesis gas
  • C01B2203/0833—Heating by indirect heat exchange with hot fluids, other than combustion gases, product gases or non-combustive exothermic reaction product gases
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  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
  • C01B2203/10—Catalysts for performing the hydrogen forming reactions
  • C01B2203/1041—Composition of the catalyst
  • C01B2203/1076—Copper or zinc-based catalysts
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  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
  • C01B2203/10—Catalysts for performing the hydrogen forming reactions
  • C01B2203/1041—Composition of the catalyst
  • C01B2203/1082—Composition of support materials
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
  • C01B2203/12—Feeding the process for making hydrogen or synthesis gas
  • C01B2203/1205—Composition of the feed
  • C01B2203/1211—Organic compounds or organic mixtures used in the process for making hydrogen or synthesis gas
  • C01B2203/1217—Alcohols
  • C01B2203/1229—Ethanol
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C2521/00—Catalysts comprising the elements, oxides or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium or hafnium
  • C07C2521/06—Silicon, titanium, zirconium or hafnium; Oxides or hydroxides thereof
  • C07C2521/08—Silica
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C2523/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00
  • C07C2523/16—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00 of arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
  • C07C2523/20—Vanadium, niobium or tantalum

Definitions

• the present invention relates to a process for the catalytic dehydrogenation of ethanol, in particular implementing at least one multitubular reactor with condensation of a heat transfer fluid.
• the present invention also relates to a process for the production of butadiene from ethanol which comprises as a first reaction step the process of catalytic dehydrogenation of ethanol in a multitubular reactor with condensation of the coolant fluid to produce acetaldehyde, followed by a second reaction step producing butadiene from a mixture of ethanol and acetaldehyde.
• the dehydrogenation reaction of ethanol to acetaldehyde can be a first reaction step in several processes, such as for example in a process for the conversion of ethanol into butadiene, known in particular under the name of the Ostromislensky process and associated with the process Lebedev.
• the Catofin® process from ABB the Catofin® process from ABB
• the OleflexTM process from UOP the Star Process® process from Thyssenkrupp
• the PDH process uses fixed-bed reactors heated from the outside by a fuel.
• the Star Process® process carries out the reaction in tubes placed in an oven on a charge diluted with steam. It appears that the choice of reactor technology depends at least in part on the catalyst used for the alkane dehydrogenation being implemented.
• Multitubular reactors also called reactor-exchangers, can be used to allow processes to operate under isothermal or pseudo-isothermal conditions. This is the case, for example, of the isopropanol dehydration process described in US Pat. No. 5,227,563 from Mitsui Petrochemical. In this patent, isopropanol is dehydrated to propylene in the presence of alumina, between 290°C and 320°C in a vertical tubular reactor, 0.5 m long and 25.4 mm internal diameter, to obtain isopropanol conversions of at least 85% and a propylene selectivity of 79% or more.
• Patent application WO 2018/046515 describes a process for dehydrating isobutanol to butene comprising a simultaneous dehydration and isomerization step, carried out under isothermal or pseudo-isothermal conditions at a temperature of 300°C or 350° C, in the presence of a catalyst comprising an FER zeolite, in a multitubular reactor.
• the isobutanol conversion rates obtained by this process are of the order of 100%, with a butene selectivity of at least 97%.
• Application FR 3 089 973 finally describes a process for dehydrating ethanol into ethylene, in a multitubular reactor, in the presence of ZSM-5 zeolite and at an inlet temperature of the charge in the tubes between 420 and 430°C. .
• salts molten at 470°C are used as heat transfer fluid. Under these conditions, the ethanol conversion rates achieved are greater than 99% with an ethylene selectivity of at least 98%.
• An object of the invention is therefore to provide a process for the dehydrogenation of ethanol to acetaldehyde, making it possible to achieve satisfactory conversion of ethanol and selectivity to acetaldehyde, while avoiding premature deactivation of the catalyst and limiting high consumption of utilities such as steam and minimizing investment and operating costs.
• the invention relates to a process for the dehydrogenation of ethanol into acetaldehyde, comprising a stage of dehydrogenation of a feed comprising ethanol, said dehydrogenation stage implementing a reaction section comprising at least one multitubular reactor which comprises one or a plurality of tubes and a shell, said tube(s) each comprising at least one fixed bed of at least one dehydrogenation catalyst, said feed supplying said tube(s) in gaseous form, at an inlet temperature of said load greater than or equal to 240°C, at an inlet pressure of said load between 0.1 and 1.0 MPa, and at a weight hourly space velocity (PPH) of the load in entry between 2 and 3:15 p.m., a heat transfer fluid circulating in said shell so that said heat transfer fluid is introduced into said shell in gaseous form and is, at the shell outlet, at least partly in liquid form, said heat transfer fluid being introduced into the shell at a flow rate such that the ratio of the weight flow rate of said heat transfer fluid entering
• the present invention implements a reactor of the reactor-exchanger type and according to a particular mode of condensation of the heat transfer fluid.
• the phase change enthalpy of the heat transfer fluid can thus be used to provide the heat necessary for the energy needs of the ethanol dehydrogenation reaction.
• the present invention also makes it possible to have a homogeneous temperature on the outer wall of the tubes inside which the reaction is carried out.
• the present invention thus makes it possible to achieve satisfactory ethanol conversion rates and high acetaldehyde selectivity, in particular ethanol conversion rates greater than or equal to 25, preferably of the order of 35% and a selectivity for acetaldehyde greater than 90%.
• Another advantage of the invention lies in the fact that the thermal compensation is obtained without adding a diluent to the charge which appears necessary, in particular when adiabatic reactors are used, to "thermally buffer” the temperature drop induced by the endothermicity of the reaction by transmitting its sensible heat to the reaction.
• the diluent conventionally used as a “thermal buffer” is water vapour.
• too high a water content in the reactor for example a water content greater than 20% by weight relative to the total weight of the charge, can be detrimental to the dehydrogenation catalyst and cause its early deactivation.
• the ethanol dehydrogenation process of the present invention does not require any addition of diluent and then makes it possible to limit the risk of early deactivation of the dehydrogenation catalyst.
• the present invention also offers the advantage of being able to dehydrogenate ethanol feedstocks of very diverse compositions and origins, for example being able to comprise water mixed with ethanol.
• the present invention can indeed be applied to ethanol feedstocks produced from renewable sources derived from biomass, often called “bioethanol. It can also be applied to an ethanol-rich effluent, for example obtained after treatment of a reaction effluent resulting in particular from the conversion of ethanol into butadiene and advantageously recycled to the reaction section, said reaction section comprising in particular a stage of dehydrogenation of the ethanol as described in patent FR 3 026 100.
• the present invention allows the dehydrogenation of the ethanol-rich effluent obtained in step E1) of patent FR 3 026 100 and which can comprise for example up to 18% by weight of water.
• the fact of avoiding the addition of a diluent in the charge advantageously makes it possible to limit the size of the equipment and the number of subsequent separation steps and consequently to minimize the investment and operating costs of the process. , in particular with respect to a process for the dehydrogenation of ethanol requiring dilution with steam.
• the present invention has yet another advantage: that of avoiding the multiplication of the number of necessary catalytic beds. Indeed, with the technology of adiabatic reactors, a succession of fixed beds of catalysts, intercalated with heat exchangers, is necessary to compensate for the endothermy of the reaction and achieve an ethanol conversion of around 30%. .
• the present invention which proposes to use a multitubular reactor coupled to the particular mode of condensation of a suitable heat transfer fluid, makes it possible to achieve the targeted conversion rates (between 25% and 35%, or even between 30 and 35 %) and a high acetaldehyde selectivity (greater than or equal to 90%), while limiting the investment and operating costs of the process.
• the expressions "between .... and " and “between .... and " are equivalent and mean that the limit values of the interval are included in the range of values described . If this was not the case and the limit values were not included in the range described, such precision will be provided by the present invention.
• the various ranges of parameters for a given stage such as the pressure ranges and the temperature ranges can be used alone or in combination.
• a range of preferred pressure values can be combined with a range of more preferred temperature values.
• the invention thus relates to a process for the dehydrogenation of ethanol to acetaldehyde, comprising, preferably consisting of, a step of dehydrogenating a feedstock comprising ethanol, preferably at least 50% by weight of ethanol, preferably at least 70% by weight of ethanol, preferably at least 80% by weight of ethanol, and optionally water, in which:
• said dehydrogenation step implements a reaction section comprising at least one multitubular reactor which comprises one or a plurality of tubes, preferably a plurality of tubes and a shell, said tube(s) being very advantageously made of steel of any type, preferably of alloy steel and preferably of stainless steel, preferably having a length between 1.0 and 6.0 m, preferably between 2 .0 and 3.0 m, preferably an internal diameter between 30.0 and 60.0 mm, preferably between 40.0 and 50.0 mm, and preferably a tube wall thickness between 1.5 and 5, 0 mm, preferably between 2.0 and 4.0 mm and more preferably between 2.2 and 3.2 mm,
• each tube comprises at least one fixed bed comprising at least one dehydrogenation catalyst, said dehydrogenation catalyst preferably comprising at least the element copper on an inorganic support, preferably silica, said catalyst very advantageously being in the form of particles of average equivalent diameter between 0.5 and 10.0 mm, preferably between 1.0 and 5.0 mm,
• said feed supplies said tube(s) in gaseous form, at an inlet temperature of said feed into the tube(s) greater than or equal to 240°C, preferably between 240°C and 350°C, preferably between 250°C and 300°C, preferably between 260°C and 290°C, at an inlet pressure of said charge in the tube(s) between 0.1 and 1.0 MPa, preferably between 0.2 and 0.5 MPa, preferably between 0.3 and 0.4 MPa, and at an hourly space velocity (PPH) of the charge at the inlet of the multitubular reactor between 2 and 15 h 1 , preferably between 2 and 10 h 1 ,
• PPH hourly space velocity
• a heat transfer fluid circulates in said shell, preferably co-current with the load in the tube(s), so that said heat transfer fluid is introduced into said shell in gaseous form and is, at the shell outlet , at least partly in liquid form,
• said heat transfer fluid is introduced into the shell of said multitubular reactor at a rate such that the ratio of the weight flow rate of said heat transfer fluid entering the shell relative to the weight flow rate of said feed entering said tubes is greater than or equal to 1.0, preferably greater than or equal to 1.5, and advantageously less than or equal to 10.0, preferably less than or equal to 5.0, preferably less than or equal to 2.0,
• said coolant is introduced into the shell of said multitubular reactor at an inlet temperature of the coolant greater than or equal to 260°C, preferably greater than or equal to 270°C, preferably greater than or equal to 290°C, and less than or equal to 400°C, preferably less than or equal to 380°C, and at an inlet pressure of the heat transfer fluid greater than or equal to 0.10 MPa, preferably greater than or equal to 0.13 MPa, of preferably greater than or equal to 0.20 MPa, and less than or equal to 1.10 MPa, preferably less than or equal to 0.85 MPa; said process producing a dehydrogenation effluent comprising at least acetaldehyde, hydrogen, and unconverted ethanol.
• the feedstock treated in the dehydrogenation process is a feedstock comprising ethanol.
• said filler comprises at least 50% by weight of ethanol, preferentially at least 70% by weight of ethanol, more preferably at least 80% by weight of ethanol.
• the charge for the dehydrogenation process may also optionally comprise water, preferably at a content of less than 50% by weight, preferably less than 30% by weight, preferably less than 20% by weight, for example between 1 and 20% weight of water in relation to the total weight of the load.
• the feed in particular comprising less than 50% by weight of ethanol, can be concentrated, prior to the process of the invention, by any means known to those skilled in the art, for example by distillation, by absorption, by pervaporation, by extraction with a solvent.
• Said filler may comprise impurities, in addition to water, such as butanol, preferably at a content less than or equal to 10% by weight, preferably less than or equal to 5% by weight, preferably less than or equal to 2 % weight, relative to the total weight of said load.
• the feedstock treated in the process according to the invention is optionally obtained by a process for the synthesis of alcohol from fossil resources such as, for example, from coal, natural gas or carbonaceous waste.
• the feed advantageously comes from non-fossil resources. It can be obtained from renewable sources derived from biomass, often called “bioethanol”.
• Bioethanol is a feedstock produced biologically, preferably by fermentation of sugars derived, for example, from sugar plant crops such as sugar cane (sucrose, glucose, fructose, and sucrose), beets, or even starchy plants (starch ) or lignocellulosic biomass or hydrolyzed cellulose (majority glucose and xylose, galactose), containing variable amounts of water.
• sugar plant crops such as sugar cane (sucrose, glucose, fructose, and sucrose), beets, or even starchy plants (starch ) or lignocellulosic biomass or hydrolyzed cellulose (majority glucose and xylose, galactose), containing variable amounts of water.
• sugar plant crops such as sugar cane (sucrose, glucose, fructose, and sucrose), beet
• Said feed can also advantageously be obtained from synthesis gas.
• Said filler can also advantageously be obtained by hydrogenation of the corresponding acids or esters.
• acetic acid or acetic esters are advantageously hydrogenated using hydrogen to ethanol.
• Acetic acid can advantageously be obtained by carbonylation of methanol or by fermentation of carbohydrates.
• Said feed can also be an ethanol effluent, obtained after treatment (in particular after separation and purification steps) of an effluent resulting from a process for converting ethanol into butadiene.
• the feedstock of the dehydrogenation process can be an effluent ethanol mainly comprising ethanol, that is to say comprising at least 50% by weight, preferably at least 70% by weight, preferably at least 80% by weight of ethanol, and obtained after treatment of a reaction effluent from the conversion of ethanol to butadiene, said ethanol effluent being advantageously recycled to the reaction section which comprises in particular a stage of dehydrogenation of the ethanol.
• the feed comprising ethanol is an ethanol-rich effluent, advantageously obtained at the end of a step for treating the effluents of an ethanol conversion process in butadiene, such as for example the ethanol-rich effluent advantageously obtained at the end of step E1) of the process described in patent FR 3 026 100.
• This ethanol-rich effluent may comprise in particular up to 18% by weight of 'water.
• the dehydrogenation process comprises at least one stage of dehydrogenation of said feed comprising ethanol, so as to produce a dehydrogenation effluent advantageously comprising at least acetaldehyde, hydrogen and conventionally unconverted ethanol.
• Said dehydrogenation effluent obtained may also comprise water, in particular when the feedstock itself comprises water. It can also comprise impurities, in particular already present in the feed, and/or co-products in particular generated during the dehydrogenation reaction.
• Said dehydrogenation step implements a reaction section comprising at least one multitubular reactor in which the dehydrogenation reaction takes place.
• the reaction section can comprise at least two multitubular reactors, and preferably less than ten multitubular reactors.
• the reaction section comprises two multitubular reactors, one being in operation, that is to say fed with charge and implementing the dehydrogenation reaction, the other being in regeneration-replacement mode.
• in regeneration-replacement mode means that the multitubular reactor is not fed with a charge comprising ethanol and that the catalyst is being regenerated or charged, or is regenerated and/or charged and is ready to operate (i.e. waiting for operation).
• each multitubular reactor comprises one or a plurality of tubes and a shell.
• the dehydrogenation reaction advantageously takes place in the tube(s) of the multitubular reactor(s), advantageously in operation.
• the tube(s) of the multitubular reactor(s) can also be called reaction tube(s).
• the shell is the envelope, typically cylindrical, of the reactor inside which the tubes are located, preferably parallel to each other and to the walls of the shell when there are several tubes, and in which a fluid circulates. coolant.
• the calender can also comprise one or more baffles or any other system, preferably distributed in such a way homogeneous in the shell, to allow a good diffusion and homogenization of the heat transfer fluid and therefore a good distribution of the heat.
• the shell and the tubes can have a particular design or a particular texture making it possible to promote the condensation and/or the evacuation of the heat transfer fluid.
• each tube comprises at least one fixed bed comprising at least one dehydrogenation catalyst.
• each tube contains a fixed bed of a dehydrogenation catalyst.
• said dehydrogenation catalyst comprises at least the element copper, and optionally the element chromium, on an inorganic support, preferably silica.
• the dehydrogenation catalyst is in the form of particles of average equivalent diameter between 0.5 and 10.0 mm, preferably between 1.0 and 5.0 mm.
• the average equivalent diameter defines an average equivalent surface diameter, advantageously determined by the laser diffraction method and the equivalent average diameter of the particles advantageously corresponds to the average diameter of spheres having the same specific surface as said particles.
• the dehydrogenation catalyst can be the Octolyst® 2001 or Octolyst® 2009 catalyst marketed by Evonik.
• the multitubular reactor(s) comprise(s) a plurality of tubes in the shell, preferably at least 100 tubes, preferably at least 1000 tubes, preferably at least 2000 tubes.
• multitube reactors comprise up to 20,000 tubes, preferably up to 10,000 tubes.
• each multitube reactor can contain between 5,000 and 6,000 tubes.
• the reaction tube(s) have a length of preferably between 1.0 and 6.0 m, more preferably between 2.0 and 3.0 m.
• all the tubes of said multitubular reactor advantageously have the same length, except for the precision due in particular to the manufacture and machining of the tubes.
• the internal diameter of each reaction tube is preferably between 30.0 and 60.0 mm, preferably between 40.0 and 50.0 mm.
• the reaction tube(s) has(have) a wall thickness preferably between 1.5 and 5.0 mm, preferably between 2.0 and 4.0 mm and preferably between 2.2 and 3.2mm.
• the nominal diameter, or external diameter, of a tube can vary between 33 and 70 mm, preferably between 44 and 56 mm.
• the specific dimensioning of the reaction tube(s), in particular the length, the internal diameter and the thickness of the wall, is advantageously adapted to the pressures exerted on the tube side (that is to say at inside the tube(s)) and on the shell side (i.e. outside the tube(s)), while advantageously making it possible to limit pressure losses at the inside the tube(s) and therefore to avoid the negative impact of the drop in pressure on the performance of the dehydrogenation reaction, in particular to avoid a drop in the conversion of the ethanol.
• the size of the multitubular reactor of stage c) of dehydrogenation like the diameter of the calender, can be adapted by those skilled in the art according to general knowledge, depending in particular on the number of tubes, their length and their diameter.
• Multitubular reactors in particular industrial ones, and in particular the tubes of said reactors, are conventionally made of a material which is inert with respect to the reaction, typically steel or nickel.
• the tube(s) of the multitubular reactor(s) in the dehydrogenation process is (are) preferably made of steel of any type, preferably alloy steel and preferably stainless steel.
• the shell of the multitubular reactor(s), as well as any baffle possibly present in the shell is made of the same material as the reaction tubes, preferably steel of any type, preferably steel alloy and preferably stainless steel.
• the charge is introduced in gaseous form into said tube(s) of each multitubular reactor, advantageously in operation, preferably at one of the ends of the reaction tube(s) and preferably simultaneously in all of the reaction tubes of the multitubular reactor when the latter contains a plurality of tubes.
• the load feeds the reaction tube(s) at an inlet temperature of said load greater than or equal to 240°C, preferably between 240°C and 350°C, preferably between 250°C and 300°C, preferably between 260°C and 290°C, at an inlet pressure of said charge between 0.1 and 1.0 MPa, preferably between 0.2 and 0.5 MPa, preferably between 0.3 and 0.4 MPa, and at a weight hourly space velocity (PPH) of the charge at the inlet of the multitubular reactor between 2 and 15 lr 1 , preferably between 2 and 10 h 1 , in particular between 3 and 7 h 1 , for example 5 h 1 .
• PPH weight hourly space velocity
• the feed rate at the inlet of the multitubular reactor which comprises for example between 4,000 kg and 30,000 kg, preferably between 14,000 kg and 17,000 kg, of dehydrogenation catalyst, can vary between 20,000 and 150,000 kg. kg/h, preferably between 50,000 and 100,000 kg/h, more preferably between 70,000 and 85,000 kg/h.
• the hourly space velocity by weight also called hourly weight velocity (PPH, weight per hourly weight)
• PPH hourly weight velocity
• the inlet temperature of said feed into the multitubular reactor(s) can advantageously be gradually increased, while advantageously remaining within the range of inlet temperatures noted above, to compensate at least in part the deactivation of the dehydrogenation catalyst.
• the dehydrogenation step of the process according to the invention can optionally implement a feed heating section, upstream of the reaction section.
• the heating of the charge in the optional heating section can be done by any method known to those skilled in the art, for example by heat exchange with a fluid which can very particularly be the heat transfer fluid circulating in the calender.
• the flow of the load can be in ascending or descending mode, preferably descending, in each tube.
• a heat transfer fluid circulates in the calender, of the multitubular reactor(s) advantageously in operation, in particular between the said reaction tubes, advantageously in co-current or in counter-current, in such a way preferably co-current, of the flow circulating inside the reaction tubes.
• the heat transfer fluid is introduced into the shell of the multitubular reactor(s) in gaseous form and is, at the shell outlet, at least partly in liquid form (that is to say in liquid form or in a gas-liquid mixture).
• the heat transfer fluid is advantageously introduced into the shell in the form of saturated vapor (that is to say in the vapor phase at the point of bubble) and condenses partly (or at least partly) on contact tubes inside which the dehydrogenation reaction takes place, which is an endothermic reaction.
• the heat transfer fluid is chosen so as to be thermally stable under the operating conditions described above.
• the choice of heat transfer fluid can also be guided by other constraints: preferably, the heat transfer fluid is inert with respect to the reactants and the products of the dehydrogenation reaction; preferably, the heat transfer fluid does not induce corrosion of the equipment, such as the multitubular reactor or the ducts.
• the heat transfer fluid has a single boiling point at a given pressure. It is in particular advantageously chosen so that it has a boiling point or a range of saturated vapor temperatures (which depends on the vapor pressures) compatible with the dehydrogenation reaction and/or such as its enthalpy of change of phases from gaseous to liquid state covers the energy requirement of the dehydrogenation reaction.
• the heat transfer fluid is an oil, preferably comprising a eutectic mixture of organic compounds, preferably of two organic compounds having very advantageously close boiling points, preferably with saturated vapor pressures such as the difference between the saturation vapor pressures of the organic compounds of the oil, at a given temperature, is less than or equal to 50 Pa, preferably less than or equal to 20 Pa, preferably less than or equal to 10 Pa.
• the heat transfer fluid comprises, preferably consists of, a mixture of biphenyl and diphenyl oxide.
• the heat transfer fluid is the oil marketed by Dow under the name DOWTHERMTM A.
• the heat transfer fluid is introduced into the shell of the multitubular reactor, advantageously in operation, at an inlet temperature of the heat transfer fluid greater than or equal to 260° C., preferably greater than or equal to 270° C., preferably greater than or equal to at 290°C, and less than or equal to 400°C, preferably less than or equal to 380°C, and at an inlet pressure of the heat transfer fluid greater than or equal to 0.10 MPa, preferably greater than or equal to 0 1.13 MPa, preferably greater than or equal to 0.20 MPa, and less than or equal to 1.10 MPa, preferably less than or equal to 1.06 MPa and preferably less than or equal to 0.85 MPa.
• the heat transfer fluid is introduced into the shell, advantageously in the form of saturated vapor, preferably at a temperature greater than or equal to 260° C. and a pressure greater than or equal to 0.10 MPa, preferably a temperature greater than or equal to 270°C and a pressure greater than or equal to 0.13 MPa, preferably at a temperature greater than or equal to 290°C and a pressure greater than or equal to 0.20 MPa, and preferably at a temperature less than or equal to 400° C. and a pressure less than or equal to 1.10 MPa, preferably at a temperature less than or equal to 380° C. and a pressure less than or equal to 0.85 MPa.
• the inlet temperature and/or pressure of the heat transfer fluid in the shell can be gradually increased, advantageously within the inlet temperature and pressure ranges noted above, to compensate at least in part for the deactivation of the catalyst. of dehydrogenation.
• the mass flow rate of said heat transfer fluid in the shell is advantageously adjusted so that the ratio of the mass flow rate of said heat transfer fluid in the shell relative to the mass flow rate of the charge introduced into the tube(s) is greater than or equal to 1.0 , preferably greater than or equal to 1.5, and advantageously less than or equal to 10.0, preferably less than or equal to 5.0, preferably less than or equal to 2.0.
• the temperature advantageously remains constant along each of the tubes of the reactor and equal at the condensation temperature of the heat transfer fluid.
• the temperature is thus homogeneous for all the tubes and very close to the shell temperature, which is interesting from a reactor design point of view since, the temperature being homogeneous throughout the reactor, the expansion of the reactor material, will be the same between the tubes and between the tubes and the shell during operation, leading to a reduction in the cost of the equipment.
• the dehydrogenation process may comprise a step of conditioning the heat transfer fluid comprising a phase of recovery of the heat transfer fluid at the shell outlet of the multitubular reactor of the dehydrogenation step, followed by a phase of compression and/or heating of the fluid heat transfer fluid to obtain a heat transfer fluid in gaseous form at the temperature and the inlet pressure of the heat transfer fluid in the shell of the dehydrogenation step.
• the dehydrogenation reaction of ethanol to acetaldehyde advantageously takes place under isothermal or pseudo-isothermal conditions, that is to say such that the temperature of the reaction medium at the reactor outlet (i.e. i.e. of the dehydrogenation effluent leaving the reactor) is similar to the temperature at the inlet of the feed or has a difference of less than 30°C, preferably less than 15°C, with respect to the temperature of the reactor inlet feed.
• the dehydrogenation effluent obtained at the end of the multitubular reactor advantageously in operation, has a temperature preferably greater than or equal to 230° C., preferably greater than or equal to 240° C., preferably greater than or equal to equal to 250°C and preferably greater than or equal to 260°C, and preferably less than or equal to 350°C, preferably less than or equal to 300°C, preferably less than or equal to 290°C, and a pressure at the reactor outlet comprised for example between 0.1 and 0.5 MPa and preferably between 0.2 and 0.4 MPa.
• the specific conditions of the process according to the invention thus make it possible to achieve the desired performance.
• the use of a reactor-exchanger under the specific operating conditions of the invention very advantageously makes it possible to obtain ethanol conversion rates of at least 25%, preferably of at least 30% , or even an ethanol conversion of 35%, and a high selectivity for acetaldehyde, in particular at least 90% by weight.
• these performances are achieved without adding a thermal diluent which could have harmful consequences on the activity of the dehydrogenation catalyst and without multiplying the number of catalytic beds and/or reactors as in a process comprising a sequence of reactors adiabatic, thus making it possible to limit investment and operating costs.
• the heat supply method proposed by the invention also makes it possible to easily adapt the operating conditions to the evolution and possible deactivation of the catalyst.
• the conversion of the ethanol charge is defined, in mass percentage, by the following formula:
• the hourly mass of ethanol entering or leaving corresponds to the mass flow rate entering or leaving the multitubular reactor, and can be determined conventionally, for example by gas phase chromatography.
• the transformation of the charge can be accompanied by deactivation of the dehydrogenation catalyst, for example by coking, by adsorption of inhibitor compounds and/or by sintering.
• the dehydrogenation catalyst can therefore advantageously periodically undergo regeneration or replacement.
• the method comprises a regeneration-replacement step.
• the reaction section preferably comprises at least two multitubular reactors.
• the multitubular reactors are used in an alternating mode, also called swing mode, in order to alternate the reaction (or operation) phases and the regeneration and/or replacement phases of said dehydrogenation catalyst.
• the objective of the regeneration is to burn off the organic deposits as well as the species containing nitrogen and sulfur, contained on the surface and within said dehydrogenation catalyst.
• the replacement makes it possible to replace the spent catalyst, that is to say which has been used during at least one dehydrogenation stage, with fresh dehydrogenation catalyst, that is to say which has not yet been used. .
• the regeneration of the dehydrogenation catalyst can be advantageously carried out by oxidation of the coke and of the inhibiting compounds under air flow or under an air/nitrogen mixture, for example by using a recirculation of the combustion air with or without water in order to dilute oxygen and controlling the regeneration exotherm.
• the oxygen content is advantageously adjusted at the inlet of the reactor by an air make-up.
• the regeneration preferably takes place at a pressure between atmospheric pressure and the reaction pressure.
• the regeneration-replacement step comprises:
• the replacement of the dehydrogenation catalyst in particular the replacement of the spent catalyst with fresh catalyst, preferably comprising at least the element copper on an inorganic support, preferably silica, or
• the regeneration of the dehydrogenation catalyst preferably comprising at least three phases, with at least a first phase of a nitrogen sweep at a temperature preferably between 200 and 350°C, preferably between 250 and 300°C , at least a second phase of flushing with a gas comprising oxygen, preferably comprising nitrogen and oxygen, at a temperature of between 300 and 650°C, preferably between 350°C and 600° C., advantageously until there is no longer any oxygen consumption, a sign of complete combustion of the coke, and at least a third phase of a nitrogen sweep at a temperature of preferably between 200 and 350°C.
• the regeneration may optionally also comprise a phase of redispersion of the active phase preferably comprising at least the element copper and optionally the element chromium, on the inorganic support, preferably silica.
• the dehydrogenation effluent obtained at the end of the reaction section of the dehydrogenation stage which comprises at least acetaldehyde, hydrogen, optionally water, and ethanol not converted, can be sent to a separation section to optionally separate at least part of the hydrogen generated during the dehydrogenation reaction.
• the dehydrogenation effluent obtained at the end of the reaction section, or the effluent obtained at the end of the separation section, can also undergo, either directly or indirectly, a treatment so as to separate a stream comprising the unconverted ethanol, said unconverted ethanol stream then being able to be recycled to the reaction section to supply the multitubular reactor(s) optionally mixed with the charge.
• the dehydrogenation process according to the invention can be integrated as a reaction step in a more global ethanol conversion process.
• the dehydrogenation process according to the invention can be integrated into a process for the production of butadiene from ethanol, as the first reaction step for converting ethanol into acetaldehyde and is advantageously followed by a second reaction step of conversion of an ethanol-acetaldehyde mixture into butadiene.
• a method for producing butadiene from ethanol, in two reaction steps can for example be the method described in patent FR 3 026 100.
• step A) of the method described in patent FR 3 026 100 is replaced by the dehydrogenation process described above in this description, and steps B), C1), D1), D2), D3), E1), E2), and optional steps C2), D2bis), F ) of the process described in patent FR 3 026 100 remaining identical.
• the present invention further relates to a process for the production of butadiene from an ethanol feed comprising at least 80% by weight of ethanol, comprising at least:
• a butadiene conversion step comprising at least one reaction section B supplied with at least a fraction or all of said dehydrogenation effluent from step A), or any ethanol/acetaldehyde effluent from the optional separation section of stage A), optionally with a liquid effluent rich in ethanol advantageously from stage C1), with a fraction or all of an effluent rich in acetaldehyde advantageously from stage E1), operated in the presence of a catalyst, preferably comprising the element tantalum and a inorganic support preferably comprising silica, at a temperature between 300°C and 400°C, preferably between 320°C and 370°C, and at a pressure between 0.1 and 1.0 MPa, preferably between 0.1 and 0.5 MPa, preferably between 0.1 and 0.3 MPa, the feed rates being adjusted so that the molar ratio of ethanol relative to acetaldehyde at the inlet of said reaction section is between 1 and 5, preferably between 1 and 3.5, more
• a compression section compressing said gaseous effluent from step B) to a pressure of between 0.1 and 1.0 MPa, preferably between 0.1 and 0.7 MPa, preferably between 0, 2 and 0.5 MPa, optionally said compressed gaseous effluent from step B) then being cooled to a temperature between 25°C and 60°C, preferably between 30°C and 40°C,
• a gas-liquid washing section comprising a washing column fed at the top at a temperature between 20 and -20°C, preferably between 15°C and 5°C, by an ethanol stream consisting of the ethanol feed of the process and optionally a fraction of the ethanol-rich effluent advantageously from stage E1), and at the bottom by said gaseous effluent from stage B) compressed in section i) and optionally cooled, producing at least a washing liquid effluent and a gaseous by-product effluent, and
• a distillation section operated at a pressure of between 0.1 and 1 MPa, preferably between 0.2 and 0.5 MPa, fed at least by the liquid effluent from said step B) and by the liquid effluent from said gas-liquid scrubbing section, producing at least a crude butadiene effluent and an ethanol/acetaldehyde/water effluent;
• D2) a step for the first purification of the butadiene comprising at least one gas-liquid washing section supplied at the bottom by the crude butadiene effluent from D1) and at the top by a flow of water which may be a flow of water from origin external to said butadiene production process and/or a fraction of the water effluent advantageously resulting from stage E1), said water flow preferably being cooled prior to the gas-liquid washing section to a temperature below 25°C, preferably less than 20°C, said gas-liquid washing section being advantageously operated at a pressure of between 0.1 and 1 MPa, said gas-liquid scrubbing section producing a pre-purified butadiene effluent at the top and a waste water effluent at the bottom;
• a subsequent butadiene purification step supplied at least with said pre-purified butadiene effluent from said step D2), and producing at least one purified butadiene effluent, said subsequent purification step advantageously implementing a drying section of said pre-purified butadiene effluent from said step D2) preferably in the presence of at least one adsorbent, then at least one cryogenic distillation section or at least one distillation and extractive distillation section;
• step E2) a step for removing impurities and brown oils, fed at least by the ethanol/acetaldehyde/water effluent from step D1), and by at least a fraction of a water-rich effluent advantageously from step E1), and producing at least one water/ethanol/acetaldehyde raffinate, a light brown oil effluent and a heavy brown oil effluent, said step for removing impurities and brown oils preferably implementing at least:
• a washing/backwashing section operated at a pressure between 0.1 and 0.5 MPa, preferably between 0.2 and 0.4 MPa, and fed with the ethanol/acetaldehyde/water effluent from step D1) and preferably at the bottom with a hydrocarbon effluent and at the top with at least a fraction of the water-rich effluent advantageously from stage E1), said hydrocarbon and water-rich effluent preferably being at a temperature between 10 and 70°C, preferably between 45 and 55°C, and producing said water/ethanol/acetaldehyde raffinate and a hydrocarbon extract,
• the ethanol-rich effluent obtained in stage E1 and recycled as feedstock for stage A) during which the dehydrogenation of the ethanol is carried out can conventionally comprise up to at 18% water weight.
• the dehydrogenation process according to the invention appears particularly advantageous in this butadiene production process insofar as the ethanol-rich effluent, supplying the dehydrogenation reaction section, conventionally comprising up to 18% by weight of water, does not make it possible to consider adding steam as a thermal diluent in the charge of the dehydrogenation stage without early deactivation of the dehydrogenation catalyst, the performance of which is generally reduced when the charges comprise 20% by weight or more of water .
• Example 1 illustrates a dehydrogenation process according to the invention.
• the charge to be treated comprises 82% weight of ethanol and 18% weight of water.
• the dehydrogenation reaction is carried out in an alloy steel multitube reactor whose tubes include a fixed bed of Octolyst® 2001 catalyst marketed by Evonik.
• the charge is introduced into the tubes in gaseous form, simultaneously.
• the heat transfer fluid used is DowthermTM A oil from Dow, and is introduced into the shell in gaseous form, in particular in the form of saturated vapor.
• Table 1 summarizes all the reactor parameters and operating conditions used.
• the dehydrogenation effluent is recovered at the reactor outlet at a flow rate of 78,346 kg/h, a temperature of approximately 277° C. and a pressure of approximately 0.29 MPa (i.e. a pressure drop of approximately 0. 6 bar, i.e. about 0.06 MPa).
• a gas-liquid mixture of DowthermTM A oil is recovered.
• the dehydrogenation effluent obtained is analyzed by gas chromatography. It has the following composition:
• Example 2 illustrates a process implementing the dehydrogenation reaction in adiabatic reactors.
• Example 2 The same charge as that of Example 1 is treated by the method of Example 2: it comprises 18% by weight of water and 82% by weight of ethanol.
• the dehydrogenation reaction is carried out in a succession of 11 axial adiabatic reactors in series, each comprising a fixed bed of dehydrogenation catalyst (Octolyst® 2001) and between which heat exchangers are inserted to heat the liquid flow between each bed.
• the reaction unit therefore comprises 11 adiabatic reactors in series and 10 heat exchangers.
• the charge which comprises 82% by weight of ethanol and 18% by weight of water, is introduced into the first reactor at an inlet temperature of 275° C., at an inlet pressure of 0.57 MPa and at a flow rate of 78,346 kg/h, corresponding to a pph of 2 lr 1 with respect to ethanol.
• Table 2 presents the parameters of the adiabatic reactors with axial fixed beds, the operating conditions and the ethanol conversion rates obtained.
• the pressure at the outlet of the eleventh reactor is 0.25 MPa.
• Example 3 illustrates a process implementing the dehydrogenation reaction in adiabatic reactors in the presence of a thermal diluent.
• the charge which is treated by the method of Example 3 is for its part diluted with steam to a dilution of 60% weight of water for 40% weight of ethanol.
• This charge is introduced into a series of radial adiabatic reactors each comprising a fixed bed of dehydrogenation catalyst and between which heat exchangers are inserted to heat the liquid flow between each bed.
• the charge, which comprises 40% by weight of ethanol and 60% by weight of water, is introduced into the first reactor at an inlet temperature of 275° C., at an inlet pressure of 0.37 MPa and at a flow rate of 78,346 kg/h.
• Table 3 presents the parameters of the radial fixed-bed adiabatic reactors, the operating conditions and the ethanol conversion rates obtained.
• the pressure at the outlet of reactor no. 4 is 0.20 MPa.
• Table 3 A dilution of the ethanol by 60% by weight with water vapor makes it possible to achieve an ethanol conversion of 35% after only 4 adiabatic reactors.

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• 2020
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