Use of a heterogeneous copper / zinc catalyst for the continuous gas-phase synthesis of methylisobutyl ketone and / or methylisobutylcarbinol by hydrogenation of mesityl oxide

Abstract

Use of a heterogeneous copper / zinc catalyst for the continuous gas-phase synthesis of methylisobutyl ketone and / or methylisobutylcarbinol by hydrogenation of mesityl oxide. The present invention relates to the use of a catalyst comprising a mixture of copper and zinc for the continuous gas-phase synthesis of methylisobutyl ketone (MIBK) and / or methylisobutylcarbinol (MIBC) from mesityl oxide. The invention also relates to a synthesis process comprising the following successive steps: continuous injection of the reactants in gaseous form through a reactor (R); hydrogenation reaction within the reactor (R) under hydrogen pressure and at a temperature between 120 and 250 °C in the presence of the catalyst as defined above; condensation of the stream from the reactor and separation of the gas stream from the liquid stream; purification of the liquid stream to separate the methylisobutyl ketone and / or methylisobutylcarbinol. [Fig. 1]

Description

Title of the invention: Use of a heterogeneous copper / zinc catalyst for the continuous gas-phase synthesis of methyl isobutyl ketone and / or methyl isobutyl carbinol by hydrogenation of mesityl oxide Technical field

[0001] The present invention relates to the use of a heterogeneous copper / zinc catalyst for the continuous and gas-phase synthesis of methylisobutyl ketone and / or methylisobutylcarbinol by hydrogenation of mesityl oxide. Technical background

[0002] Methylisobutyl ketone, or 4-methyl-2-pentanone, is an excellent solvent for resins used in the production of surface coatings. It is also widely used in the rubber industry as a precursor to antioxidant or antiozonant additives, primarily N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD). Methylisobutyl ketone is also used as a solvent in the synthesis of active pharmaceutical ingredients and as a solvent for the extraction of precious metals.

[0003] Methylisobutylcarbinol, or 4-methyl-2-pentanol, is primarily used as a synthetic intermediate for additives in lubricating oils, such as zinc dialkyldithiophosphates (ZDDP, an anti-wear and corrosion inhibitor), and as a foaming agent in the processing of ores (copper) and coal via flotation separation processes. Methylisobutylcarbinol is also a good solvent for mineral and vegetable oils, nitrocellulose, and natural and synthetic resins. It is thus used in paints and varnishes based on alkyd or epoxy resins.

[0004] It is known to prepare methylisobutyl ketone, commonly called MIBK, and methylisobutylcarbinol, commonly called MIBC, industrially by a 3-step process from acetone according to the following reaction sequence:

[0005] [Chem.l]

[0006] After aldolization of acetone (ACE) in the presence of an alkali catalyst, the intermediate diacetone alcohol (DAA) undergoes intramolecular dehydration via acid catalysis to lead to mesityl oxide commonly called OM (consisting of a mixture of OM-a and OM-[3] isomers) which is then hydrogenated to MIBK and MIBC.

[0007] The hydrogenation of OM is most often carried out in the liquid phase, in a stirred reactor in the presence of a nickel-based catalyst (FR 1 471 545, CN 113773170) or through a fixed bed of catalyst such as nickel supported on kieselghur (FR 1 478 704) or Pd / C (JP 3939042).

[0008] Hydrogenation leads to a mixture of MIBK and MIBC with a higher or lower concentration of MIBK or MIBC depending on the operating conditions and the nature of the catalyst used. The use of a hydrogenation catalyst consisting of a noble metal from the platinum group, such as Pd / C (JP3939042), allows the preparation of MIBK with a selectivity greater than 99%, while with a nickel-based catalyst (CN 113773170), it is possible to achieve a MIBC yield of between 84 and 94%.

[0009] US patent 3,449,435 describes a process for the simultaneous production of a saturated carbonyl compound (including MIBK) and a saturated alcohol (including MIBC) by catalytic hydrogenation of an unsaturated aldehyde or an unsaturated ketone (including OM), in the gas phase at 150-250 °C, in the presence of a mixture of hydrogen and an alkane (methane, ethane, or propane). Starting from OM and passing through a fixed bed of copper chromite, the relative proportions of MIBK and MIBC formed are adjusted by varying the amount of hydrogen and the alkane / hydrogen molar ratio.

[0010] Methylisobutyl ketone can also be prepared industrially according to a single-step integrated process from acetone by implementing a ca A multifunctional catalytic cell allows for the sequential and in situ execution of aldol condensation, dehydration, and hydrogenation reactions. The most commonly described catalytic system consists of a noble metal such as palladium dispersed on an acidic ion-exchange resin (DE 1,238,453; US 3,953,517; CN 111217689) or on zeolite (US 3,666,816). The synthesis, carried out in the liquid phase under hydrogen pressure, leads to MIBK with selectivities exceeding 90%. Besides isopropanol, a co-product recycled during the synthesis, the second most important co-product is diisobutyl ketone (DIBK), not MIBC.

[0011] Methylisobutylcarbinol can also be prepared by specific hydrogenation of MIBK obtained previously according to the preceding methods. The hydrogenation can be carried out in the liquid phase (CN 110871076, CN 110903164) or in the gas phase (CN 112979416, EP 3 603 801) with, for example, nickel-, copper-, or cobalt-based catalysts supported on alumina. The selectivities of MIBC for MIBK are most often greater than 98%. Technical problem to solve

[0012] If mesityl oxide is chosen as a reagent, the conversion must be total, due to the very small difference between the boiling points of OM and MIBC which are therefore very difficult to separate by distillation.

[0013] Only the synthesis route of MIBC by hydrogenation of MIBK in the gas or liquid phase allows for the selective production of MIBC. However, liquid-phase processes require operation at higher pressures than gas-phase processes and therefore necessitate more expensive reaction equipment.

[0014] MIBK can be obtained selectively by direct routes but this is done from catalysts composed of noble or precious metals and therefore also expensive.

[0015] There is therefore a need to develop an inexpensive catalyst allowing the common but nevertheless selective synthesis of MIBK or MIBC as required, in combination with a gas phase process.

[0016] The inventors have found that by using mesityl oxide (OM) as a reagent with the catalyst according to the invention, and in gas phase and continuously, it was possible to selectively synthesize MIBK or MIBC, or a mixture of MIBK and MIBC. Brief description of the invention

[0017] The present invention relates to the use of a catalyst for the continuous gas-phase synthesis of methyl isobutyl ketone (MIBK) and / or methyl isobutylcarbinol (MIBC) from mesityl oxide, characterized in that the catalyst comprises a mixture of copper and zinc, the Cu / Zn weight ratio being between 0.23 and 1.25, preferably between 0.33 and 0.63.

[0018] The invention also relates to a continuous gas-phase synthesis process for methylisobutyl ketone and / or methylisobutylcarbinol from mesityl oxide comprising the following successive steps: a) continuous injection in gaseous form through a reactor (R) of a mesityl oxide stream and a hydrogen stream then b) hydrogenation reaction within reactor (R) under a hydrogen pressure greater than or equal to atmospheric pressure and at a temperature between 120 and 250 °C in the presence of a catalyst as defined above then c) condensation of the flow from the reactor and separation of the gas flow from the liquid flow then d) purification of the liquid stream from step c) to separate the methylisobutyl ketone and / or methylisobutylcarbinol.

[0019] Other advantageous characteristics of the catalyst according to the invention are specified below. -The catalyst comprises copper in a content of 15 to 45% by weight, preferably between 20 to 40% by weight and preferably between 20 to 30% by weight, zinc is in a content of 36 to 65% by weight, preferably between 45 to 65% by weight and preferably between 48 to 60% by weight in relation to the total weight of the catalyst. -The catalyst includes neither a support nor a promoter.

[0020] Other advantageous features of the process according to the invention are specified below. -The pressure in the reactor (R) is less than 10 bars, and preferably between 1 and 5 bars. -According to one embodiment, the temperature in the reactor (R) is between 150 and 175 °C to predominantly synthesize methylisobutylcarbinol (MIBC). Preferably, the pressure in the reactor (R) is between 2 and 10 bar, and preferably between 2 and 5 bar. Advantageously, the process includes a step of recycling the methylisobutyl ketone stream from the purification step d) back to step a). -According to one embodiment, the temperature in the reactor (R) is between 180 and 240 °C to predominantly synthesize methylisobutyl ketone (MIBK). Preferably, the pressure in the reactor (R) is less than 3 bar, and preferably between 1 and 3 bar. Advantageously, the process includes a step of recycling the methylisobutylcarbinol stream from the purification step d) back to step a). -The molar ratio of hydrogen to mesityl oxide is strictly greater than 1, of Preference between 2 and 20 and even more preferentially between 2.5 and 10. - The purification step d) comprises several successive purification steps: f) a distillation step (D2) of the organic stream recovered in the previous step, with MIBK being recovered at the top of the distillation column (D2) then g) a distillation step (D3) of the organic stream recovered at the bottom of the distillation column (D2) of the previous step f), the MIBC being recovered at the bottom of the distillation column (D3). -The process includes a step e) of water extraction, before step f).

[0021] The catalyst according to the invention allows the simultaneous synthesis of MIBK and MIBC in controlled proportions, depending on the operating conditions of the process and highly adjustable to the respective commercial demands for MIBK and MIBC. The catalyst according to the invention thus allows the simultaneous synthesis of MIBK and MIBC, or the selective synthesis of MIBK, or the selective synthesis of MIBC, within the same installation. Therefore, depending on the chemical species to be synthesized—MIBC or MIBK—it is unnecessary to change the installation or the catalyst within the reactor. A simple adjustment within the process, described below, allows the synthesis to be directed toward one species or the other.

[0022] The process according to the invention thus allows the simultaneous synthesis of MIBK and MIBC or, alternatively, the specific production of MIBK with recycling of MIBC or the specific production of MIBC with recycling of MIBK.

[0023] In other words, compared to known processes, this process allows the direct and selective synthesis of MIBC in a single step by hydrogenation of OM, and moreover, by means of an inexpensive catalytic system. This process also allows the direct and selective synthesis of MIBK in a single step by hydrogenation of OM, and moreover, by means of an inexpensive catalytic system. Brief description of the figures

[0024] [Fig. 1] is a diagram of the device implementing the claimed method.

[0025] [Fig.2] is a diagram of the device implementing an embodiment of the claimed process for the selective synthesis of MIBC.

[0026] [Fig.3] is a diagram of the device implementing an embodiment of the claimed process for the simultaneous synthesis of MIBK and MIBC.

[0027] [Fig.4] is a diagram of the device implementing an embodiment of the claimed process for the selective synthesis of MIBK. Detailed description

[0028] Other features, aspects, objects and advantages of the present invention will become even clearer upon reading the following description.

[0029] It is specified that the expressions "from ... to ..." and "between ... and ..." used in this description should be understood as including each of the mentioned terminals.

[0030] The catalyst

[0031] The present invention relates to the use of a heterogeneous copper / zinc catalyst for the continuous gas-phase synthesis of methylisobutyl ketone (MIBK) and / or methylisobutylcarbinol (MIBC) from mesityl oxide (OM) according to the following reactions: [Chem 2]

[0032] The catalyst according to the invention is a heterogeneous catalyst comprising a mixture of copper and zinc, the weight ratio Cu / Zn being between 0.23 and 1.25, preferably between 0.30 and 0.88, and more particularly between 0.33 and 0.63.

[0033] Advantageously, the catalyst according to the invention comprises: -copper in a content of between 15 and 45% by weight, preferably between 20 and 40% by weight and even more preferably between 20 and 30% by weight, and -zinc in a content of between 36 and 65% by weight, preferably between 45 and 65% by weight and even more preferably between 48 and 60% by weight relative to the total weight of the catalyst.

[0034] Preferably, the catalyst comprises copper oxide and zinc oxide. The catalyst may also comprise one or more supports corresponding to metallic oxidized compounds, in particular selected from Al₂O₃, ZrO₂, TiO₂ and mixtures thereof. Preferably, the catalyst according to the invention does not comprise a support.

[0035] The catalyst may include promoters, such as metal oxides, in particular selected from chromium oxides, manganese oxides, molybdenum oxides, cerium oxides and mixtures thereof, or metal oxides alkali or alkaline earth metals, in particular selected from sodium oxides, potassium oxides, cesium oxides, magnesium oxides, calcium oxides, barium oxides and mixtures thereof. Preferably, the catalyst according to the invention does not comprise a promoter.

[0036] Preferably, the catalyst according to the invention does not include a support or a promoter.

[0037] The catalyst can be in the form of a fixed catalytic bed comprising one or more layers of heterogeneous catalyst based on copper and zinc, preferably, the catalytic bed consists of a single layer of catalyst.

[0038] The catalyst is preferably used in the form of pellets or in the form of extruded elements which may contain one or more shaping auxiliaries such as graphite.

[0039] The heterogeneous catalysts in oxidized form initially loaded into the reactor can be activated by reduction under a flow of hydrogen, at a temperature of 150 to 400 °C and preferably from 200 to 350 °C.

[0040] Most preferably, the catalyst, after activation, comprises more than 90%, preferably more than 95% by weight of copper and zinc oxide relative to the total weight of the catalyst.

[0041] The process

[0042] The invention also relates to a continuous gas-phase synthesis process of methylisobutyl ketone (MIBK) and / or methylisobutylcarbinol (MIBC) from mesityl oxide (OM) using the catalyst as defined above.

[0043] The method according to the invention comprises the following successive steps: a) continuous injection in gaseous form through a reactor, denoted R below, of a mesityl oxide stream and a hydrogen stream then b) hydrogenation reaction within reactor R under a hydrogen pressure greater than or equal to atmospheric pressure and at a temperature between 120 and 250 °C in the presence of a catalyst as described above, then c) condensation of the flow from the reactor and separation of the gaseous flow from the liquid flow, then d) purification of the liquid stream from step c) to separate the methylisobutyl ketone and / or methylisobutylcarbinol.

[0044] a) Injection of reagents

[0045] The synthesis is carried out by continuous injection through a reactor R of a mesityl oxide stream and a hydrogen stream. Preferably, the reactor is tubular in shape.

[0046] The hydrogenation reaction is carried out in reactor R under a hydrogen pressure greater than or equal to atmospheric pressure at a temperature between 120 and 250 °C. However, mesityl oxide is in liquid form at ambient temperature. It is therefore necessary to bring it to a gaseous state before it enters reactor R.

[0047] An evaporator can be used for this purpose. The gas-phase reactor is supplied by first passing the liquid reactants through a steam-heated evaporator or by any other means known to those skilled in the art. All reactants are introduced into the reactor in gaseous form, i.e., mesityl oxide and hydrogen, as well as any recycling streams from subsequent steps of the process.

[0048] The temperature of the evaporator is fixed so as to ensure the passage of the reactants from the liquid state to the gaseous state under the pressure conditions implemented; the gases being simultaneously drawn towards the inlet of the reactor with the flow of gaseous hydrogen.

[0049] The evaporator may consist of one or more heat exchangers mounted in parallel and / or in series of any type known to those skilled in the art. Preferably, it consists of one or more vertical tube-bund heat exchangers.

[0050] The mass flow rate of liquid reactants per unit volume of catalytic bed (MVH) can be between 0.15 and 1.5 kg / Lh, preferably between 0.3 and 1.2 kg / Lh and more preferably between 0.5 and 1.0 kg / Lh

[0051] b) Hydrogenation reaction of mesityl oxide

[0052] The hydrogenation reaction is carried out in reactor R under a hydrogen pressure greater than or equal to atmospheric pressure and at a temperature between 120 and 250 °C in the presence of a catalyst as defined above.

[0053] The catalyst may have been activated beforehand. Preferably, the catalyst initially loaded into the reactor may be activated by reduction under a flow of hydrogen, at a temperature of 150 to 400 °C, and preferably from 200 to 350 °C.

[0054] The reactor R can consist of one or more tubular or multitubular reactors in parallel. Preferably, the reactor is placed vertically and the entire gaseous reaction mixture is fed into the bottom of the reactor and thus passes through the entire catalytic bed from bottom to top.

[0055] The hydrogenation reaction is carried out under an absolute pressure greater than or equal to atmospheric pressure, preferably less than 10 bars. It is preferably between 1 and 10 bars, preferably between 1 and 5 bars.

[0056] The hydrogenation reaction is carried out at a temperature between 120 and 250 °C, preferably between 150 and 240 °C.

[0057] According to one embodiment of the invention, for the majority production of MIBC, the temperature is preferably between 150 and 175 °C. Preferably, the pressure in reactor R is between 2 and 10 bar, and preferably between 2 and 5 bar.

[0058] According to one embodiment of the invention, for the majority production of MIBK, the temperature is preferably between 180 and 240 °C. Preferably, the pressure in reactor R is less than 3 bar, and preferably between 1 and 3 bar.

[0059] When the hydrogenation reaction is carried out at a temperature above 175 and below 180°C, then the reaction leads to a mixture of equal parts of MIBC and MIBK.

[0060] The hydrogenation reaction is carried out under hydrogen pressure with preferably a molar ratio of hydrogen (H2) / mesityl oxide (OM) greater than 1, preferably between 2 and 20, and more preferably between 2.5 and 10.

[0061] The process according to the invention makes it possible to use a single catalyst having the characteristics and composition described above for the simultaneous production of MIBK and MIBC or alternatively the specific production of MIBK or the specific production of MIBC, said productions being adjusted by different temperature ranges, and preferably associated with pressure ranges.

[0062] c) Condensation step of the stream from the reactor and separation of the gas stream from the liquid stream

[0063] The reaction mixture from reactor R in the form of a gaseous stream is condensed before being purified. The condenser C may consist of one or more heat exchangers mounted in parallel and / or in series of any type known to those skilled in the art. Preferably, it consists of one or more vertical shell-and-tube heat exchangers. The cooling fluid may be water and / or ethylene glycol or any other refrigerant known to those skilled in the art.

[0064] After being condensed, the stream can be introduced into a separator in order to separate the gas stream consisting mainly of hydrogen and the liquid stream consisting mainly of MIBK and / or MIBC.

[0065] d) Liquid stream purification step to separate the methylisobutyl ketone and / or the methylisobutylcarbinol

[0066] The liquid stream obtained at the end of step c) is then purified in order to isolate the methylisobutyl ketone and / or the methylisobutylcarbinol.

[0067] Preferably, the purification step d) of the liquid stream is carried out continuously through several successive purification steps: e) a possible step of separating water from the organic stream, then f) a step of separating the MIBK from the organic stream from the previous step and; (g) a step of separating the MIBC from the organic stream from the previous step.

[0068] The separation steps are advantageously carried out by distillation. These distillation steps may comprise one or more distillation columns in parallel.

[0069] Distillations can be carried out under reduced pressure or under an absolute pressure greater than or equal to atmospheric pressure; the columns can be at identical or different pressures depending on the compositions of the mixtures to be separated. Preferably, the distillations will be carried out under a column head pressure equal to atmospheric pressure.

[0070] Each distillation column comprises at least one bottom boiler and at least one top condenser. The columns may be either tray columns or packed columns.

[0071] e) Optional step of separating water from the organic stream

[0072] During the hydrogenation reaction, water may have formed through secondary reactions involving the formation of heavy metals and / or through the possible hydrogenolysis of MIBC to methylpentane. Therefore, a step to extract any water formed must be carried out before separating and purifying the MIBK and / or MIBC.

[0073] The water extraction step is preferably carried out using a distillation column denoted Dipermendant to remove the water at the top of the column in the form of binary heteroazeotropes MIBK / H2O and MIBC / H2O as well as any light by-products.

[0074] Possible settling step

[0075] Advantageously, the overhead stream recovered at the top of the distillation column Di is introduced into a decanter to separate the aqueous and organic phases by gravity. The upper organic phase can be reinjected at the top of the column Db. Continuous purging of the organic phase can be carried out to prevent the accumulation of light impurities.

[0076] If necessary, the purge can be subjected to specific treatment in order to recover the residual MIBK and MIBC contained in this purge. Preferably, this treatment can be carried out by distillation.

[0077] Possible step of purifying the aqueous effluent

[0078] The lower aqueous phase of the decanter can feed a distillation column which removes residual organic products solubilized in the aqueous phase at the top of the column. This column head stream can be recycled back to the decanter feed.

[0079] f) MIBK distillation step

[0080] If step e) is carried out, the raw organic stream recovered at the bottom of column Di and comprising very predominantly MIBK and / or MIBC feeds a distillation column denoted D2.

[0081] If step e) is not carried out, the condensed organic stream from step c) feeds the distillation column marked D2.

[0082]

[0083]

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[0094]

[0095] Any residual water is removed at the top of column D2 via the binary heteroazeotrope MIBK / H20. This flow can be returned to the column feed when step e) is completed. It is possible to recover MIBK with a purity greater than 99.7%, extracted via a lateral draw-off at the top of column D2. All or part of the purified MIBK stream can be recycled before the reactor, depending on the proportions of the productions respectively targeted in MIBK and / or MIBC. g) MIBC distillation step The liquid stream recovered at the bottom of column D2 and consisting mainly of MIBC feeds a distillation column D3. The light stream extracted at the top of column D3 consists mainly of residual MIBK which can be recycled before the reactor, depending on the proportions of production respectively targeted in MIBK and / or MIBC. It is possible to recover MIBC with a purity greater than 98.5% and preferably greater than 99.5%, via a lateral withdrawal at the bottom of column D3. Heavy impurities, which may include 2,6,8-trimethyl-4-nonanone (TMN-one) and 2,6,8-trimethyl-4-nonanol (TMN-ol), are removed at the bottom of column D3. [Chem. 3] Possible recycling After the hydrogenation reaction, the hydrogen-containing gas streams can be recycled to the hydrogen line, which injects this reactant into the evaporator or reactor. These hydrogen-containing gas streams can be recovered at the separator. It is also possible to recycle organic streams containing MIBC and / or MIBK to the mesityl oxide injection line, which injects this reagent into the evaporator.

[0096] According to a first embodiment, which aims at the selective synthesis of MIBC, the hydrogenation reaction is carried out at a temperature between 150 and 175 °C. The recovered MIBK stream is recycled and mixed with mesityl oxide. Preferably, the pressure in reactor R is between 2 and 10 bar, and preferably between 2 and 5 bar.

[0097] According to a second embodiment, which aims at the selective synthesis of MIBK, the hydrogenation reaction is carried out at a temperature between 180 °C and 240 °C, the recovered MIBC stream is recycled and mixed with mesityl oxide. Preferably, the pressure in reactor R is less than 3 bar, and preferably between 1 and 3 bar. Description of Figure 1

[0098] [Fig-1] is a diagram of the device implementing the claimed method.

[0099] Mesityl oxide is introduced via line 1 into evaporator Ev. Hydrogen is introduced via line 2 into evaporator Ev. The entire gas stream exiting the evaporator is introduced into the multitubular reactor R via line 3.

[0100] The gaseous reaction mixture from reactor R, comprising unreacted hydrogen, MIBK, MIBC and water, is introduced into condenser C via line 4.

[0101] The liquid and gaseous flow exiting the condenser C is introduced into a separator S via the pipe 5. The gaseous flow exits at the head of the separator S via the pipe 6.

[0102] The liquid flow exiting the separator S via the line 7 feeds a purification device D, in which step d) is carried out. The purification device D separates the MIBC via the line 8 and the MIBK via the line 9. Description of Figure 2

[0103] [Fig.2] is a diagram of the device implementing an embodiment of the claimed process for the selective synthesis of MIBC.

[0104] Mesityl oxide is introduced via line 10 into evaporator Ev. Make-up water is injected via line 11 into evaporator Ev and hydrogen is introduced via line 12 into evaporator Ev. The entire gas stream exiting the evaporator is introduced into the multitubular reactor R via line 13.

[0105] The gaseous reaction mixture from reactor R, comprising unreacted hydrogen, MIBK and MIBC and water, is introduced into condenser C via line 14.

[0106] The liquid and gaseous flow exiting the condenser C is introduced into a separator S via the line 15. The gaseous flow exiting the head of the separator S is recycled via the line 16 to the line 12. A purge Pi is provided at the point of the line 16.

[0107] The gas flow can be returned to the feed of the reaction section by means of a booster (not shown in the diagram).

[0108] A purging Pi of this gaseous stream is advantageously carried out continuously in order to avoid the accumulation of non-condensable impurities such as hydrocarbons.

[0109] The liquid flow exiting at the bottom of the separator S feeds the distillation column Di via the line 17.

[0110] The light fraction containing the aqueous phase is recovered at the top of column Di and is introduced into the decanter di via the line 18.

[0111] After separation within the decanter dh, the upper organic phase is reinjected at the top of column Di via line 19. The lower aqueous phase is extracted via line 20.

[0112] The organic stream recovered at the bottom of column Di and comprising very mainly MIBC and minor MIBK feeds the distillation column D2 via the line 21.

[0113] The residual light impurities contained in this organic stream are extracted at the top of column D2 and recycled to line 17 via line 22. The minor MIBK recovered by means of a lateral draw-off at the top of column D2 via line 23 is recycled in whole or in part to the feed line 10 via line 25.

[0114] The organic stream drawn off at the bottom of column D2 and consisting mainly of MIBC feeds the distillation column D3 via line 24. The light fraction extracted at the top of column D3 and consisting mainly of residual MIBK is recycled to line 10 via line 25.

[0115] The pure MIBC is recovered by means of a withdrawal at the bottom of column D3 via pipe 26.

[0116] Heavy residues at the base of column D3 are removed via the SL line.

[0117] According to the embodiment shown in [Fig.2], the hydrogenation reaction is carried out at a temperature between 150 and 175 °C. Preferably, the pressure in reactor R is between 2 and 10 bar, and preferably between 2 and 5 bar. Description of Figure 3

[0118] [Fig.3] is a diagram of the device implementing an embodiment of the claimed process for the simultaneous synthesis of MIBK and MIBC.

[0119] Mesityl oxide is introduced via line 30 into evaporator Ev. Make-up water is injected via line 31 into evaporator Ev and hydrogen is introduced via line 32 into evaporator Ev. The entire gas stream exiting the evaporator is introduced into the multitubular reactor R via line 33.

[0120] The gaseous reaction mixture from reactor R, comprising hydrogen not having reacted, MIBK and MIBC and water is introduced into condenser C via pipe 34.

[0121] The liquid and gaseous flow exiting the condenser C is introduced into a separator S via the line 35. The gaseous flow exiting the head of the separator S is recycled via the line 36 to the line 32. A purge Pi is provided at the point of the line 36.

[0122] The gas flow can be returned to the feed of the reaction section by means of a booster (not shown in the diagram).

[0123] A purging Pi of this gas stream is advantageously carried out continuously in order to avoid the accumulation of non-condensable impurities such as hydrocarbons.

[0124] The liquid flow exiting at the foot of the separator S feeds the distillation column Di via the line 37.

[0125] The light fraction containing the aqueous phase is recovered at the top of column Di and is introduced into the decanter di via the line 38.

[0126] After separation within the decanter dh, the upper organic phase is reinjected at the top of column Di via line 39. The lower aqueous phase is extracted via line 40.

[0127] The organic stream recovered at the bottom of column Di and comprising a mixture of MIBC and MIBK feeds the distillation column D2 via line 4L

[0128] The residual light impurities contained in this organic stream are extracted at the top of column D2 and recycled to line 37 via line 42.

[0129] Pure MIBK is recovered by means of a lateral withdrawal at the top of column D2 via pipe 43. MIBK can be recycled in whole or in part to the feed pipe 30 via pipes 44 and then 47.

[0130] The organic stream drawn off at the bottom of column D2 and consisting mainly of MIBC feeds the distillation column D3 via line 45. The light fraction extracted at the top of column D3 and consisting mainly of residual MIBK is recycled to line 30 via lines 46 and then 47.

[0131] The pure MIBC is recovered by means of a withdrawal at the bottom of column D3 via pipe 48. The MIBC can be recycled in whole or in part to pipe 30 via pipe 47.

[0132] Heavy residues at the base of column D3 are removed via the SL line.

[0133] According to the embodiment shown in [Fig. 3], the hydrogenation reaction is carried out at a temperature between 120 and 250 °C. Preferably, the pressure in reactor R is less than 10 bar. Description of Figure 4

[0134] [Fig.4] is a diagram of the device implementing an embodiment of the claimed process for the selective synthesis of MIBK.

[0135] Mesityl oxide is introduced via line 50 into evaporator Ev. Water is injected via line 51 into evaporator Ev and hydrogen is introduced via line 52 into evaporator Ev. The entire gas flow exiting the evaporator is introduced into the multitubular reactor R via line 53.

[0136] The gaseous reaction mixture from reactor R, comprising unreacted hydrogen, MIBK and MIBC and water, is introduced into condenser C via line 54.

[0137] The liquid and gaseous flow exiting the condenser C is introduced into a separator S via the line 55. The gaseous flow exiting the head of the separator S is recycled via the line 56 to the line 52. A purge Pi is provided at the point of the line 56.

[0138] The gas flow can be returned to the feed of the reaction section by means of a booster (not shown in the diagram).

[0139] A purging Pi of this gas stream is advantageously carried out continuously in order to avoid the accumulation of non-condensable impurities such as hydrocarbons.

[0140] The liquid flow exiting at the bottom of the separator S feeds the distillation column Di via the line 57.

[0141] The light fraction containing the aqueous phase is recovered at the top of column Di and is introduced into the decanter di via the line 58.

[0142] After separation within the decanter, the upper organic phase is reinjected at the top of column Di via line 59. The lower aqueous phase is extracted via line 60.

[0143] The organic stream recovered at the bottom of column Di and comprising predominantly MIBK and minor MIBC feeds the distillation column D2 via the line 61.

[0144] The residual light impurities contained in this organic stream are extracted at the top of column D2 and recycled to line 57 via line 62. The pure MIBK is recovered by means of a lateral draw-off at the top of column D3 via line 63.

[0145] The organic stream drawn off at the bottom of column D2 and consisting mainly of MIBC feeds the distillation column D3 via line 64. The light fraction extracted at the top of column D3 and consisting mainly of residual MIBK is recycled to line 50 via lines 65 and then 66.

[0146] Minority MIBC recovered by means of a withdrawal in the lower part of column D3 is recycled in whole or in part to the feed line 50 via line 66.

[0147] Heavy residues at the base of column D3 are removed via the SL line.

[0148] According to the embodiment shown in [Fig. 4], the hydrogenation reaction is carried out at a temperature between 180 and 240 °C. Preferably, the pressure in reactor R is less than 3 bar, and preferably between 1 and 3 bar. Examples

[0149] Three examples were carried out in order to demonstrate the effectiveness and selectivity of the process of the invention.

[0150] Abbreviations and definitions: ACE: acetone ISO: isopropanol MIBK: methyl isobutyl ketone MIBC: methyl isobutyl carbinol OM: mesityl oxide MVH: hourly mass flow rate of feed per unit volume of the reactor (unit: kg / Lh) NL: NormoLitre corresponds to a volume of IL under normal conditions of pressure (1.013 bar) and temperature (273 K).

[0151] Conversion: TT0M = transformation rate of the implemented OM = conversion of the OM TTOM = 100 x (number of moles of OM converted) / number of moles of OM implemented with: number of moles of OM converted = (number of moles of OM used - number of moles of OM at reactor outlet) Selectivity: SP = selectivity in product P with respect to the converted MO SMIBK = 100 x (number of moles of MIBK formed) / number of moles of MO converted SMIBC = 100 x (number of moles of MIBC formed) / number of moles of MO converted with: number of moles of P formed = (number of moles of P at reactor outlet - number of moles of P recycled to reactor feed)

[0152] The conversions and selectivities are calculated on the basis of the mass compositions of the crude mixtures at the outlet of the reactor; compositions determined by gas-phase chromatographic analyses. Example No. 1: MIBC Summary

[0153] The synthesis is carried out using a temperature-controlled vertical tubular reactor containing a catalytic bed with a volume of 1 L and a length of 80 cm.

[0154] The catalytic bed consists of cylindrical pellets (5x4 mm) with a weight composition before activation of 35% CuO and 65% ZnO. The Cu / Zn weight ratio of the catalyst is 0.54. The trade name of the catalyst is PRICAT™ CZ 29 / 2 T supplied by Johnson Matthey.

[0155] The reactor is fed from the bottom up by the previously prepared mixture of reactants evaporated and / or preheated through an electrically heated exchanger at 150 °C.

[0156] - Preliminary catalyst activation step:

[0157] In the evaporator, heated to 150 °C, hydrogen and water are introduced at flow rates of 40 L / h and 0.6 L / h, respectively. The hydrogen and steam flow exiting the evaporator feeds the tubular reactor, which has been preheated to 250 °C and atmospheric pressure. Once the zone of highest exothermicity has passed through the entire catalytic bed, the H2 flow rate is gradually increased to 80 L / h, and then the water injection is stopped. The hydrogen introduction continues for 10 h, maintaining the reactor temperature at 250 °C under a pressure of 2.5 bar.

[0158] - Synthesis step: The reactor is then fed via the evaporator with a mixture comprising mesityl oxide, hydrogen, a water supplement and, if necessary, recycled MIBK. The purity of the mesityl oxide used is 99.64%. The mass flow rate of the water supply corresponds to 2.5% of the mass flow rate of OM. Table 1 below shows the results obtained for synthesis tests carried out after a prior cumulative use time of the catalytic bed of 2700 h under various conditions.

[0159] Operating conditions: - Reactor temperature: 160 °C - absolute pressure: 3.1 bar - molar flow rate of OM: 6 mol / h - H2 / OM molar ratio = 5

[0160] Results: In all cases, the conversion of the OM is total.

[0161] [Tab 1] Running time (h} ICM] MVH [W8K œcydée! W8K MIBC 2724 0.531 - 13.51 S5>63 2754 Q.5S1 - 13, æ S5>40 2854 O, 531 3.40 æ.02 29« 0.12 2 S.62

[0162] Table 1

[0163] Under the operating conditions implemented, it is thus possible to produce predominantly MIBC with a yield exceeding 85% compared to OM without MIBK recycling. With MIBK recycling, almost exclusive MIBC production can be achieved with a yield close to 99%. Example #2: Synthesis of MIBK and MIBC

[0164] The tests are carried out in a vertical tubular reactor containing a catalytic bed with a volume of 7 L and a length of 2.8 m.

[0165] The catalyst used is identical to that of example no. 1. It is pre-activated according to a method similar to that described in example no. 1.

[0166] During the synthesis tests, a mixture of OM, water and H2 previously evaporated and / or preheated through a steam exchanger with a temperature between 170 and 180 °C is fed from bottom to top through the catalytic bed.

[0167] The mass flow rate of the water make-up corresponds to 2.5% of the mass flow rate of OM.

[0168] Table 2 below shows the results obtained as a function of the OM flow rate, pressure, temperature and cumulative catalyst usage time for synthesis tests carried out with an H2 / OM molar ratio of 5.

[0169] Results: In all cases, the conversion of the OM is total.

[0170] [Tab 2] Operating time {»} MVH [OM] (kg / Usts-h!) Pressure (bar? Bath temperature Te m SetecivitySjGM MiBK MÏBC 733 a est 1.7 1S5 61.04 36.73 785 0.631 V 185 54?O0: 44.51 857 Q631 17 175 43.16 50.81 1007 a, 631 3.2 170 28.08 70.81 1476 0.631 2.2 170 37.17 61.53 1642 0.771 2.8 170 31.32 67.23

[0171] Table 2

[0172] These results demonstrate that the performance of this catalyst is easily modulated according to the reaction temperature and possibly the pressure, thus allowing the selectivities for MIBK (between 28 and 61%) and MIBC (between 37 and 71%) to be varied, and therefore the respective productivities for MIBK and MIBC to be adapted over a wide range. For the same feed rate of OM, the productivity for MIBK is greater as the reaction temperature is higher, while the productivity for MIBC is greater as the reaction temperature is lower. Example #3: MIBK Summary

[0173] The tests are carried out with an experimental setup similar to that of example no. 2 but with a catalytic bed with a volume of 3.5 L and a length of 1.3 m.

[0174] The catalytic bed consists of cylindrical pellets (6x3 mm) with a weight composition before activation of 31.3% CuO and 66.6% ZnO. The Cu / Zn weight ratio of the catalyst is 0.47. The trade name of the catalyst is HySat™ 350 supplied by Clariant.

[0175] The catalyst is pre-activated using a method similar to that described in example no. 1.

[0176] During the synthesis tests, the reactor is then fed via the evaporator maintained at 180 °C by a mixture comprising OM, hydrogen, a water supplement and a recycled MIBC stream.

[0177] The mass flow rate of the water make-up corresponds to 2.5% of the mass flow rate of OM.

[0178] Table 3 below shows the results obtained as a function of the MIBC recycling rate for synthesis tests carried out after a prior cumulative use time of the catalytic bed of 800 h under various conditions.

[0179] Operating conditions: - Reactor temperature: 220 °C - absolute pressure: 2.5 bar - Molar flow rate of OM: 24.5 mol / h - H2 / OM molar ratio = 5

[0180] Results: In all cases, the conversion of the OM is total.

[0181] [Tab 3] Operating time W MVH [OM] -h) MVH [recycled MIBC] (kg / Uste-h) Selectivities / OM MIBK MiBC 83.3 0.687 0.117 88.53 10.02 852 0.687 0.171 97.58 1.48 877 0.587' 0.231 103.6 -4.8

[0182] Table 3

[0183] These results demonstrate that it is possible to obtain a very selective production in MIBK with a yield between 97.5 and 99% compared to the OM implemented.

[0184] For the 877 h running test, the negative MIBC selectivity value and the MIBK selectivity value greater than 100% means that with such a MIBC recycling rate part of the recycled MIBC stream has also been transformed into MIBK.

Claims

Claims

1. Use of a catalyst for the continuous, gas-phase synthesis of methyl isobutyl ketone (MIBK) and / or methyl isobutyl carbinol (MIBC) from mesityl oxide, characterized in that the catalyst comprises a mixture of copper and zinc, the Cu / Zn weight ratio being between 0.23 and 1.25, preferably between 0.30 and 0.88, and more particularly between 0.33 and 0.

63.

2. Use according to claim 1, characterized in that the catalyst comprises copper in a content of between 15 and 45% by weight, preferably between 20 and 40% by weight and more preferably between 20 and 30% by weight, and zinc in a content of between 36 and 65% by weight, preferably between 45 and 65% by weight and more preferably between 48 and 60% by weight relative to the total weight of the catalyst.

3. Use according to claim 1 or 2, characterized in that the catalyst comprises neither support nor promoter.

4. Process for the continuous and gas-phase synthesis of methyl isobutyl ketone and / or methyl isobutyl carbinol from mesityl oxide comprising the following successive steps: a) continuous injection in gaseous form through a reactor (R) of a stream of mesityl oxide and a stream of hydrogen then b) hydrogenation reaction within the reactor (R) under a hydrogen pressure greater than or equal to atmospheric pressure and at a temperature between 120 and 250°C in the presence of a catalyst as defined in any one of claims 1 to 3 then c) condensation of the stream from the reactor and separation of the gaseous stream from the liquid stream then d) purification of the liquid stream from step c) to separate the methyl isobutyl ketone and / or methyl isobutyl carbinol.

5. Method according to claim 4, characterized in that the pressure in the reactor (R) is less than 10 bars, and preferably between 1 and 5 bars.

6. Process according to claim 4 or 5, characterized in that the temperature in the reactor (R) is between 150 and 175°C to synthesize mainly methylisobutylcarbinol (MIBC).

7. Method according to claim 6, characterized in that the pressure in the reactor (R) is between 2 and 10 bars, and preferably between 2 and 5 bars.

8. Process according to claim 6 or 7, characterized in that it comprises a step of recycling the flow of methyl isobutyl ketone from purification step d) to step a).

9. Process according to claim 4 or 5, characterized in that the temperature in the reactor (R) is between 180 and 240°C to synthesize mainly methyl isobutyl ketone (MIBK).

10. Method according to claim 9, characterized in that the pressure in the reactor (R) is less than 3 bars, and preferably between 1 and 3 bars.

11. Method according to claim 9 or 10, characterized in that it comprises a step of recycling the methylisobutylcarbinol stream from purification step d) to step a).

12. Process according to any one of claims 4 to 11, characterized in that the hydrogen / mesityl oxide molar ratio is strictly greater than 1, preferably between 2 and 20, and even more preferably between 2.5 and 10.

13. Method according to any one of claims 4 to 12, characterized in that the purification step d) comprises several successive purification steps: f) a distillation step (D2) of the organic stream recovered in the previous step, the MIBK being recovered at the top of the distillation column (D2) then g) a distillation step (D3) of the organic stream recovered at the bottom of the distillation column (D2) from the previous step f), the MIBC being recovered at the bottom of the distillation column (D3).

14. Method according to claim 13, characterized in that it comprises e) a step of extracting the water, before step f).

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