High activity catalyst for producing 1, 3-butadiene

Abstract

The present invention relates to a supported catalyst comprising a support and 0.1 to 10% by weight, based on the total weight of the catalyst, of tantalum, based on Ta2O5, and further comprising 5 to 60 ppm of aluminum and 35 to 75 ppm of sodium, based on the total weight of the catalyst. Furthermore, the present invention relates to a catalyst reaction tube for producing 1, 3-butadiene comprising at least one filler layer of a supported catalyst as defined herein; a reactor for producing 1, 3-butadiene comprising one or more catalyst reaction tubes as defined herein; and a production facility for producing 1, 3-butadiene, comprising one or more reactors as defined herein. The present invention also relates to methods of making 1, 3-butadiene as defined herein and methods of making supported catalysts as defined herein. Finally, the invention relates to the use of the supported catalyst as defined herein for the production of 1, 3-butadiene from a feed comprising ethanol and acetaldehyde and to the use of sodium in an amount of 35 to 75 ppm in a supported catalyst for the production of 1, 3-butadiene from a feed comprising ethanol and acetaldehyde for increasing the yield of 1, 3-butadiene.

Description

[0001] The present invention relates to a supported catalyst comprising a support and tantalum in an amount of 0.1 to 10% by weight, based on the total weight of the catalyst, calculated as Ta 2 O 5 and, based on the total weight of the catalyst, the supported catalyst further comprises 5 to 60 ppm of aluminum and 35 to 75 ppm of sodium. Furthermore, the present invention relates to a catalyst reaction tube for producing 1,3-butadiene, which comprises at least one packing of the supported catalyst as defined herein; to a reactor for producing 1,3-butadiene, which comprises one or more catalyst reaction tubes as defined herein; and to a production facility (plant) for producing 1,3-butadiene, which comprises one or more reactors as defined herein. The present invention also relates to a method for preparing 1,3-butadiene as defined herein and a method for preparing the supported catalyst as defined herein. Finally, the present invention relates to the use of the supported catalyst as defined herein for producing 1,3-butadiene from a feed comprising ethanol and acetaldehyde, and to the use of sodium in an amount of 35 to 75 ppm in the supported catalyst for producing 1,3-butadiene from a feed comprising ethanol and acetaldehyde for increasing the yield of 1,3-butadiene.

[0002] 1,3-Butadiene is one of the most important raw materials in the synthetic rubber industry, where it is used as a monomer for producing various synthetic polymers (e.g., polybutadiene rubber, acrylonitrile-butadiene-styrene polymer, styrene-butadiene rubber, nitrile rubber, and styrene-butadiene latex). For example, 1,3-butadiene is obtained as a by-product in the manufacture of ethylene in steam cracking of naphtha and can be separated by extractive distillation (Chem. Soc. Rev., 2014, 43, 7917; ChemSusChem, 2013, 6, 1595; Chem. Central J., 2014, 8, 53).

[0003] The depletion of non-renewable fossil fuel-derived resources and environmental considerations have recently become a powerful driving force for exploring renewable resources for 1,3-butadiene and its precursors. Among a wide range of renewable resources, biomass appears to have the greatest potential in the production of 1,3-butadiene. This strategy has two main advantages: independence from fossil fuels and reduction of CO 2 emissions (ChemSusChem, 2013, 6, 1595).

[0004] The conversion of ethanol (e.g., obtainable from biomass) to 1,3-butadiene can be carried out in two ways reported in the literature: a one-step process (Lebedev process) and a two-step process (Ostromislensky process).

[0005] The one-step process (reported by Lebedev in the early 20th century) is carried out by directly converting ethanol into 1,3-butadiene using a multifunctional catalyst whose acid-base properties are adjusted (J. Gen. Chem., 1933, 3, 698; Chem. Ztg., 1936, 60, 313).

[0006] On the other hand, the so-called two-step process can be carried out by converting ethanol into acetaldehyde in the first step. The purpose of this first step is to feed this mixture of ethanol and acetaldehyde into the second step or reactor. In the second step, the mixture containing ethanol and acetaldehyde is converted into 1,3-butadiene (Catal. Today, 2016, 259, 446) (for example, over a silica-supported tantalum catalyst).

[0007] US2018 / 0208522 A1 relates to a catalyst for converting a feed containing ethanol and acetaldehyde into 1,3-butadiene. The catalyst contains at least the element tantalum and at least one pickled mesoporous oxide matrix which contains at least 90 wt% silica before washing, and the mass of the element tantalum is in the range of 0.1% to 30% of the mass of the mesoporous oxide matrix. The teachings of US2018 / 0208522 A1 rely on the pickling of the mesoporous oxide support to improve the selectivity of the catalyst for 1,3-butadiene and / or the productivity of the catalyst for 1,3-butene. At the end of the washing step and before impregnating the active element, the catalyst contains an amount of sodium in the range of 0 to 500 ppm. The concentration of aluminum in the catalyst and the yield of 1,3-butadiene are not disclosed in US2018 / 0208522 A1.

[0008] Therefore, there has been a continuing need to provide a catalyst for producing 1,3-butadiene which exhibits high activity and is capable of providing a high yield of 1,3-butadiene.

[0009] In a first aspect, the present invention relates to a supported catalyst comprising or consisting of (i) a support, and (ii) tantalum in an amount of 0.1 to 10 wt%, preferably 2 to 4 wt%, based on the total weight of the catalyst, calculated as Ta 2 O 5 wherein the supported catalyst further contains aluminum in the range of 5 - 60 ppm, preferably 5 - 40 ppm, more preferably 6 - 30 ppm, more preferably 7 - 20 ppm, based on the total weight of the catalyst, and sodium in the range of 35 - 75 ppm, preferably 40 - 60 ppm, more preferably 40 - 50 ppm, based on the total weight of the catalyst.

[0010] During the research on which the present invention is based, it was found that the supported catalyst according to the present invention containing a certain level of sodium (and aluminum) impurities as defined in the first aspect exhibits almost the same selectivity for 1,3-butadiene as the catalyst prepared with an ultra-pure silica support (for example, a catalyst containing 6 ppm aluminum and 31 ppm sodium, respectively, based on the total weight of the catalyst). Furthermore, it was surprisingly found that the catalytic activity of the supported catalyst according to the present invention is higher than that of the catalyst prepared with an ultra-pure silica support, which advantageously leads to a significantly higher 1,3-butadiene yield (see the examples below, Table 2 and Figure 2 and 3 ).

[0011] The sodium and aluminum contents expressed in parts per million ppm herein relate to the total weight of the supported catalyst containing tantalum in the form of tantalum oxide. This also applies to the tantalum content expressed in weight % herein.

[0012] In a preferred embodiment, the support of the supported catalyst according to the present invention comprises one or more of an ordered and disordered porous silica support, other porous oxide supports, and mixtures thereof, preferably from ZrO 2 , TiO 2 , MgO, ZnO, NiO, and CeO 2 .

[0013] Most preferably, the support of the supported catalyst according to the present invention is a silica support, preferably an ordered or disordered porous silica support.

[0014] Supported catalysts are particularly advantageous because they allow control of the concentration and dispersion of active sites, simple preparation of the catalyst by impregnating a support in any form and shape, and easy access of reaction molecules to all active sites of the catalyst.

[0015] Preferably, the supported catalyst according to the present invention has a BET specific surface area in the range of 130 to 550 m 2 / g, preferably in the range of 190 to 280 m 2 / g.

[0016] Preferably, the supported catalyst according to the present invention has an average pore diameter in the range of 30 to .

[0017] Preferably, the supported catalyst according to the present invention has a pore volume in the range of 0.2 to 1.5 cm 3 / g.

[0018] The surface area (SA) and pore volume (PV) were measured by nitrogen porosimetry using an Autosorb-6 test unit from Quantachrome Corporation (now Anton Paar GmbH). The samples were first degassed on the Autosorb-6 degassing unit at 350 °C for at least 4 hours. The data points in the P / P 0 range of 0.05 to 0.30 were used to calculate the multi-point surface area using the BET theory. The pore volume measurements were recorded on the desorption leg at a P / P 0 of 0.984. Assuming cylindrical pores, the average pore diameter was calculated using the following equation:

[0019] According to a preferred embodiment of the present invention, the weight ratio of aluminum to sodium in the supported catalyst is in the range of 0.06 to 1.71, preferably 0.10 to 1.0, and most preferably 0.15 to 0.5.

[0020] In a second aspect, the present invention relates to a catalyst reaction tube for the production of 1,3-butadiene, which comprises at least one packed bed (zone) of the supported catalyst according to the present invention and one or more packed beds of inert material.

[0021] Preferably, the inert material is selected from silicon carbide, inert ceramic beds, ceramic beads, extrudates, rings with a diameter of 2 - 7 mm, stainless steel mesh, foams, and mixtures thereof.

[0022] According to a preferred embodiment, the packed bed of inert material is in contact with and separated from the packed bed of the supported catalyst according to the present invention (i.e., the reaction zone) if there are more than one packed bed of supported catalyst in the catalyst reaction tube. They are preferably located at the reactant feed inlet and outlet of the reaction tube.

[0023] According to one embodiment, the catalyst reaction tube is loaded with one packed bed of the supported catalyst according to the present invention, preferably at the center of the catalyst reaction tube. The supported catalyst according to the present invention is in contact with the packed bed of inert material on either side, i.e., the packed bed of inert material is preferably located at the feed inlet and outlet of the catalyst reaction tube. According to this embodiment, the catalyst reaction tube comprises one reaction zone.

[0024] According to another embodiment, the catalyst reaction tube is alternatively loaded with a plurality of packed beds of the supported catalyst according to the present invention and a plurality of packed beds of inert material. The packed beds of inert material are preferably located at the feed inlet and outlet of the catalyst reaction tube and are in contact with the packed beds of the supported catalyst according to the present invention. According to this embodiment, the catalyst reaction tube comprises more than one reaction zone.

[0025] In a third aspect, the present invention relates to a reactor for producing 1,3-butadiene, which comprises one or more catalyst reaction tubes according to the present invention.

[0026] In a fourth aspect, the present invention relates to a production facility for producing 1,3-butadiene, which comprises one or more reactors as defined herein, and means for regenerating the supported catalyst in said one or more reactors. Preferably, wherein said production facility further comprises a pre-reactor for producing acetaldehyde having one or more reaction tubes, said pre-reactor comprising a supported or unsupported (bulk type) catalyst, said supported or unsupported (bulk type) catalyst comprising one or more of zinc, copper, silver, chromium, magnesium and nickel, preferably comprising one or more of zinc and copper.

[0027] Tantalum oxide contained in the supported catalyst according to the present invention is inactive in the oxidation of ethanol to acetaldehyde. Therefore, in order to produce 1,3-butadiene with the supported catalyst according to the present invention, the feed stream must contain ethanol and acetaldehyde. Such a mixture of ethanol and acetaldehyde can be produced, for example, from ethanol in a pre-reactor for producing acetaldehyde in a production facility containing a supported or unsupported (bulk type) catalyst as defined above, and then fed to a reactor for producing 1,3-butadiene comprising one or more catalyst reaction tubes according to the present invention. Alternatively, ethanol and acetaldehyde can be obtained from commercial sources and directly fed to a reactor for producing 1,3-butadiene comprising one or more catalyst reaction tubes according to the present invention.

[0028] In a fifth aspect, the present invention relates to a method for producing 1,3-butadiene, which comprises: (i) contacting a feed comprising ethanol and acetaldehyde with a supported catalyst according to the present invention to obtain a crude product comprising 1,3-butadiene.

[0029] Preferably, in the method according to the invention, the contacting in (i) is carried out at a temperature of 200 - 500 °C, preferably 250 - 450 °C, more preferably 300 - 400 °C.

[0030] In a preferred embodiment of the method according to the present invention, the contacting in (i) is carried out at a weight hourly space velocity of 0.2 to 10 h -1 preferably 1 to 7 h -1 more preferably 2 to 5 h -1 of.

[0031] Preferably, the contacting in (i) is carried out at a pressure in the range of 0 to 10 bar, more preferably 1 to 3 bar, most preferably 1 to 2 bar.

[0032] Preferably, the method according to the present invention further comprises the following steps: (ii) separating the crude product into at least a first part comprising 1,3-butadiene, a second part comprising acetaldehyde, and a third part comprising ethanol; Preferably, at least a part of the second part, at least a part of the third part, or at least a part of both the second part and the third part is recycled to the feed.

[0033] In a preferred embodiment of the method according to the present invention, the contacting in (i) is carried out in a continuous stream of the feed in a reactor as defined herein.

[0034] In another preferred embodiment of the method according to the present invention, based on the total weight of the feed, the feed comprises at least 50% by weight of ethanol, preferably 60 to 75% by weight of ethanol.

[0035] In another preferred embodiment of the method according to the present invention, based on the total weight of the feed, the feed comprises at least 15% by weight of acetaldehyde, preferably 20 to 35% by weight of acetaldehyde.

[0036] In another preferred embodiment of the method according to the present invention, the molar ratio of ethanol to acetaldehyde in the feed is in the range of 1 to 7, preferably 1.5 to 5, more preferably 1.7 to 4, and most preferably 2.0 to 3.0.

[0037] In a sixth aspect, the present invention relates to a method for producing a supported catalyst according to the present invention, the method comprising the following steps or consisting of the following steps: (i) impregnating a support having an aluminum and sodium content defined by the following formula based on the weight of the catalyst support with a tantalum precursor solution to form a supported tantalum catalyst precursor, wherein the lower limit is defined by: support[M] LL = catalyst[M] LL / (1 - catalyst[Ta 2 O 5 wt%), where M = Na or Al; wherein catalyst[Na] LL = 35 ppm and catalyst[Al] LL = 5 ppm; and the upper limit is defined by: support[M] UL = catalyst[M] UL / (1 - catalyst[Ta 2 O 5 wt%), where M = Na or Al; wherein catalyst[Na] UL = 75 ppm and catalyst[Al]UL = 60 ppm; (ii) drying the supported tantalum catalyst precursor, and (iii) calcining the dried supported tantalum catalyst precursor to form a supported tantalum catalyst.

[0038] In the above formula, the carrier [M] LL represents the lower limit of the concentration (wt. / wt.) of metal M (M is sodium or aluminum respectively) in the carrier to be used and impregnated in step (i), which depends on a. the catalyst [M] LL , i.e., the lower limit of the concentration (wt / wt.) of metal M (M is sodium or aluminum respectively) in the supported catalyst according to the present invention finally obtained in step (iii), and b. the catalyst [Ta 2 O 5 wt%, i.e., the concentration (wt. / wt.) of Ta 2 O 5 in the supported catalyst according to the present invention finally obtained in step (iii).

[0039] Similarly, in the above formula, the carrier [M] UL represents the upper limit of the concentration (wt. / wt.) of metal M (M is sodium or aluminum respectively) in the carrier to be used and impregnated in step (i), which depends on a. the catalyst [M] UL , the upper limit of the concentration (wt / wt.) of metal M (M is sodium or aluminum respectively) in the supported catalyst according to the present invention finally obtained in step (iii), and b. the catalyst [Ta 2 O 5 wt%, the concentration (wt. / wt.) of Ta 2 O 5 in the supported catalyst according to the present invention finally obtained in step (iii).

[0040] The preferred embodiments of the sodium and aluminum contents of the supported catalyst according to the first aspect of the present invention correspond to the preferred embodiments of the catalyst [M] LL and the catalyst [M] UL with respect to the sixth aspect of the present invention.

[0041] In a preferred embodiment, the carrier impregnated in step (i) of the method according to the present invention includes one or more of ordered and disordered porous silica, other porous oxides, and mixtures thereof, preferably from ZrO 2 , TiO 2 , MgO, ZnO, NiO, and CeO2 .

[0042] Preferably, the support impregnated in step (i) of the method according to the invention is a silica support, preferably an ordered or disordered porous silica support.

[0043] According to a preferred embodiment of the method for producing a supported catalyst according to the invention, the supported catalyst is a silica-supported catalyst, and the method comprises or consists of the following: (i) Reacting an aqueous silicate solution, preferably sodium silicate, with an acid to form a hydrogel, (ii) Dispersing, preferably by spraying, more preferably by spraying into air and breaking into droplets, and gelling the hydrogel to form hydrogel beads, (iii) One or more optional additional steps of (pre)-aging, acidification, washing, and pH adjustment, a. Aging the hydrogel beads at a temperature T1, b. Acidifying the aged hydrogel beads, c. Washing the aged and acidified hydrogel beads, preferably with deionized water acidified to pH 3-4, d. Adjusting the pH of the washed hydrogel beads obtained in step (c), preferably to a pH in the range of about 8 to 10, (iv) Aging the hydrogel beads at a temperature T2, where T2>T1 (if applicable, for example if one of the optional steps in (iii) is used), (v) Acidifying the aged hydrogel beads (obtained in step (iv)), (vi) Washing the aged and acidified hydrogel beads (obtained in step (v)), preferably with deionized water acidified to pH 3-4, (vii) Adjusting the pH of the washed hydrogel beads obtained in step (c), preferably to a pH in the range of about 3 to about 10, most preferably to a pH of about 9, (viii) Drying the washed hydrogel beads obtained in step (vi) or (vii) (preferably using an oven) to obtain a silica support, (ix) Optionally, sieving the silica support obtained in step (viii) (to collect the desired particle size fraction), (x) impregnating the silica support obtained in step (viii) or (ix) with a tantalum precursor solution to form a supported tantalum catalyst precursor, preferably wherein the tantalum precursor is tantalum ethoxide, most preferably wherein the tantalum ethoxide precursor is stabilized with 2,4-pentanedione and / or dissolved in a suitable organic solvent (e.g. isopropanol), (xi) drying the supported tantalum catalyst precursor, preferably by heating under atmospheric pressure or vacuum, and (xii) calcining the dried supported tantalum catalyst precursor, preferably at a temperature of about 400-600° C. for about 2-5 hours, to form a supported tantalum catalyst.

[0044] As used herein, "supported tantalum catalyst precursor" refers to an intermediate product (eg, before calcination). In contrast, "supported tantalum catalyst" is the product after calcination.

[0045] Preferably, in the method according to the invention the temperature T1 is in the range of 20-50°C.

[0046] Preferably, in the method according to the invention the temperature T2 is in the range of 40-100°C.

[0047] In a seventh aspect, the present invention relates to the use of a supported catalyst according to the present invention for producing 1,3-butadiene from a feed comprising ethanol and acetaldehyde, preferably for increasing the yield of 1,3-butadiene.

[0048] In an eighth aspect, the present invention relates to the use of sodium in an amount ranging from 35 to 75 ppm, preferably from 40 to 60 ppm, more preferably from 40 to 50 ppm, based on the total weight of the catalyst, in a supported catalyst for producing 1,3-butadiene from a feed comprising ethanol and acetaldehyde for increasing the yield of 1,3-butadiene, the catalyst comprising or consisting of: - carrier, - 5 to 60 ppm, preferably 5 to 40 ppm, more preferably 6 to 30 ppm, most preferably 7 to 20 ppm of aluminum, based on the total weight of the catalyst, and - Take Ta 2 O 5 0.1 to 10 wt. %, preferably 2 to 4 wt. %, of tantalum, calculated and based on the total weight of the catalyst.

[0049] In a ninth aspect, the present invention relates to the use of aluminum in an amount ranging from 5 to 60 ppm, preferably from 5 to 40 ppm, preferably from 6 to 30 ppm, most preferably from 7 to 20 ppm, based on the total weight of the catalyst, in a supported catalyst for producing 1,3-butadiene from a feed comprising ethanol and acetaldehyde for increasing the yield of 1,3-butadiene, the catalyst comprising or consisting of: - A carrier, - Sodium in an amount of 35 to 75 ppm, preferably 40 to 60 ppm, more preferably 40 to 50 ppm, based on the total weight of the catalyst, and - Tantalum in an amount of 0.1 to 10% by weight, preferably 2 to 4% by weight, based on the total weight of the catalyst, calculated as Ta 2 O 5 In a tenth aspect, the present invention relates to the use of sodium in an amount in the range of 35 to 75 ppm, preferably 40 to 60 ppm, most preferably 40 to 50 ppm, based on the total weight of the catalyst, in a supported catalyst for producing 1,3 - butadiene from a feed containing ethanol and acetaldehyde, for the use of increasing the yield of 1,3 - butadiene; and the use of aluminum in an amount in the range of 5 to 60 ppm, preferably 5 to 40 ppm, more preferably 6 to 30 ppm, most preferably 7 to 20 ppm, based on the total weight of the catalyst, in a supported catalyst for producing 1,3 - butadiene from a feed containing ethanol and acetaldehyde, for the use of increasing the yield of 1,3 - butadiene. The catalyst comprises or consists of:

[0050] - A carrier, - Tantalum in an amount of 0.1 to 10% by weight, preferably 2 to 4% by weight, based on the total weight of the catalyst, calculated as Ta - Based on Ta 2 O 5 In a preferred embodiment of an aspect of the present invention (see the first to tenth aspects above), it respectively corresponds to or can be derived from the preferred embodiments of other aspects of the present invention (as defined above), as long as it is technically feasible.

[0051] Examples: 1.

[0053] 1. Preparation of silica support

[0054] The following describes the general steps for making a silica carrier according to an embodiment of the present disclosure. Figure 1 FIG. shows a flow chart of the general steps used in making a silica carrier according to an embodiment of the present disclosure. A more detailed description of the silica carrier and its preparation method can be found in co - pending U.S. Patent Application No. 16 / 804,610, which is incorporated herein by reference.

[0055] In one embodiment, a dilute sodium silicate solution with a weight ratio of 3.3 SiO 2 :Na 2 O first reacts with dilute sulfuric acid to form a hydrosol having the following composition: 12% by weight SiO 2 and H 2 SO 4 :Na2 The molar ratio of O is 0.8. As a result, the obtained hydrosol is alkaline. In one embodiment, high-purity silicate with low aluminum (based on SiO 2 by weight, <10 ppm) is used to prepare silica with a lower aluminum content.

[0056] Then the hydrosol is sprayed into the air, where it breaks into droplets and solidifies into beads with a diameter of a few millimeters, and then is captured in a solution, such as in water or a solution (such as an aqueous solution of ammonium sulfate, sodium bicarbonate, etc.) that buffers the pH of the bead / solution system to an alkaline pH of about 9. A higher aging temperature and / or a longer aging time reduces the silica surface area. Generally, for a hydrogel captured in ammonium sulfate solution to obtain a surface area of about 300 m 2 / g, the aging is carried out at 70 °C and a pH of about 9 for about 16 hours.

[0057] Then an acid is added to lower the pH to about 2. Then the hydrogel beads are washed with water acidified to a pH of about 3 to reduce the sodium level. The aged and washed hydrogel beads contain about 15-18% SiO 2 . Once washed, the pH of the beads is raised to about 9 using ammonium hydroxide solution. Then the beads are dried using an oven. Finally, the beads are sieved to obtain the desired particle size fraction. Note that the pH adjustment before drying is optional, and the beads are typically dried from pH 3-9.

[0058] In one embodiment, the described method can be modified to optionally include multiple aging steps at elevated temperatures, where each aging step is followed by an acidification and washing step to obtain a desired combination of surface area and sodium level. In one embodiment, optionally, the washing can be carried out before the aging step.

[0059] According to the procedure listed above, silica gel beads with a surface area of about 230-300 m 2 / g, a pore volume of about 0.95-1.05 cm 3 / g, aluminum <500 ppm (depending on the silicate purity and / or the process and conditions used for the washing and aging steps), and sodium <1000 ppm (depending on the extent of washing combined with multiple aging steps) can be obtained. In some cases, silica hydrogels containing small amounts of aluminum and / or sodium (on a dry basis) are contacted with solutions of aluminum sulfate and / or sodium carbonate respectively, and then dried to adjust the aluminum and / or sodium to the desired levels.

[0060] 2. Catalyst preparation

[0061] In all cases, before use, silica gel beads with a size of 2 - 5 mm are pre-dried to a loss on drying (LOD) measured at 120 °C < 0.5 wt%. The following is a general description of preparing the catalyst based on 100 g of silica support on a dry basis. Broadly speaking, the tantalum precursor is added to silica via the incipient wetness impregnation method.

[0062] For every 100 g (dry basis) of silica gel support, a stabilized tantalum precursor solution is prepared by mixing approximately 5 - 6 g of tantalum precursor (e.g., 5.7 g of tantalum ethoxide) with 2 - 3 g (e.g., 2.8 g) of 2,4-pentanedione (acetylacetone). Typically, 8.5 g of the stabilized tantalum precursor solution is dissolved in 65 - 76 g of isopropanol, and then it is added to the pre-dried silica gel beads. The amount of isopropanol is adjusted based on the pore volume of the support such that the solution is only contained within the silica pores and there is no free solution outside the pores. The impregnation takes approximately 15 - 40 minutes. The impregnated silica gel is kept in a sealed container for at least 1 hour, and then the solvent is evaporated by heating at atmospheric pressure or under vacuum. Then the dried material is calcined in air at 550 °C for 4 hours to obtain a finished catalyst with approximately 3.0 wt% Ta 2 O 5 of the finished catalyst.

[0063] Preparation of Catalyst B:

[0064] Before use, silica gel beads with a size of 2 - 5 mm are pre-dried to a loss on drying (LOD) measured at 120 °C < 0.5 wt%.

[0065] For 125 g (dry basis) of silica gel support, a stabilized tantalum precursor solution is prepared by mixing 7.1 g of tantalum ethoxide with 3.5 g of 2,4-pentanedione (acetylacetone). 10.6 g of the stabilized tantalum precursor solution is dissolved in 95 g of isopropanol, and then it is added to the pre-dried silica gel beads. The impregnation takes approximately 15 - 40 minutes. The impregnated silica gel is kept in a sealed container for at least 1 hour, and then the solvent is evaporated by heating at atmospheric pressure. Then the dried material is calcined in air at 550 °C for 4 hours to obtain a finished catalyst with 3.0 wt% Ta 2 O 5 , 41 ppm Na, and 7 ppm Al.

[0066] It can be assumed that Na and Al are present in the support since there are no substantial quantities of Na or Al in Ta-ethanol, acetylacetone, or isopropanol. Then, the amounts of Na or Al in the support and the catalyst are related by the following equation: Support [M] = Catalyst [M] / (1 - Catalyst [Ta 2 O 5 wt%), where M = Na or Al

[0067] Therefore, the Na and Al in the support were calculated to be 42.3 ppm and 7.2 ppm, respectively.

[0068] 3. Analysis method for sodium and aluminum

[0069] The levels of sodium and aluminum in the catalyst composition were determined by atomic absorption spectrometry (AA) using a Perkin-Elmer PinAAcleTM 900F spectrometer and by inductively coupled plasma (“ICP”) spectrometry using a Perkin Elmer Optima8300 ICP-OES spectrometer. The catalyst samples were digested with hydrofluoric acid (HF). The resulting silicon tetrafluoride (SiF 4 ) was fumed off, and the sodium and aluminum in the residue were analyzed. The sodium and aluminum contents were reported as parts per million of the catalyst after drying at 120 °C. If desired, the amounts of sodium and aluminum in the support and tantalum starting material can be determined accordingly.

[0070] 4. Analysis method for tantalum

[0071] The level of tantalum in the catalyst composition was measured by inductively coupled plasma (“ICP”) spectrometry using a Perkin Elmer Optima 8300 ICP-OES spectrometer. The catalyst samples were digested with hydrofluoric acid (HF). The resulting silicon tetrafluoride (SiF 4 ) was fumed off, and the tantalum in the residue was analyzed. The results were reported based on the dry weight of the catalyst calcined at 500 to 550 °C.

[0072] Table 1: Physicochemical properties of the catalysts synthesized according to the above process

[0073] 5. Catalytic test

[0074] Forty grams of the catalyst synthesized according to the above procedure were placed in a stainless-steel reactor operating in continuous flow. The reactor was initially heated to 350 °C at a nitrogen flow rate of 500 mL / min. (Nitrogen was used only during heating of the reactor, while the reaction was carried out without a nitrogen flow, but only using the specified organic feed.) Then, at 2.3 h -1At a weight hourly space velocity (WHSV) of and a pressure of 1.8 bar, a reaction was carried out using an aqueous solution of 94 wt.% ethanol and acetaldehyde mixed in a mass ratio of 2.5:1 as the feed (the 2.5 mass fraction of the 94 wt.% ethanol aqueous solution is related to the total weight of water and ethanol). The composition of the effluent was monitored regularly by an on-line gas chromatograph equipped with a flame ionization detector coupled to a mass spectrometer (GC / MS).

[0075] The catalyst loses its activity for the production of 1,3 - butadiene during operation and needs to be regenerated. Catalyst regeneration was carried out in situ in a stainless - steel reactor after a run time (TOS) of 110 hours (h) in the following four stages:

[0076] 1. Desorption and removal of organic vapors

[0077] The organic vapors were removed by purging with a nitrogen stream (gas hourly space velocity (GHSV)=300 h -1 ) at 350 °C for 5 hours.

[0078] 2. Preliminary combustion of carbon deposits

[0079] The deposits were burned in a steam - diluted air stream (GHSV = 300 h -1 ) for 15 hours. The oxygen content in the regeneration mixture (air / steam) was gradually increased from 1 vol% to 6 vol% so that the temperature in the reactor did not exceed 400 °C.

[0080] 3. Combustion of carbon deposits

[0081] The temperature of the reactor was raised to 520 °C. The deposits were finally burned in a nitrogen - diluted air stream (GHSV = 300 h -1 ) for 20 hours. The oxygen content in the regeneration mixture (air / nitrogen) was 6 vol%.

[0082] 4. Cooling

[0083] The reactor was cooled to 350 °C under a nitrogen stream (GHSV = 300 h -1 ).

[0084] The results were calculated as follows and are shown in Table 2 below (EtOH - ethanol; AcH - acetaldehyde):

[0085] Table 2: Comparison of the activity and selectivity of the fresh catalyst (Reg0) and after the first regeneration (Reg1). Process conditions: T = 350 (±5) °C, p = 1.8 bar, WHSV = 2.3 h -1, 94 wt% EtOH:AcH = 2.5:1 weight / weight; 1,3-BD = 1,3-butadiene

[0086] Figure 2 Shows a comparison of the activity and selectivity of fresh catalysts A, B, and C (Reg 0).

[0087] Figure 3 Shows a comparison of the activity and selectivity of catalysts A, B, and C after the first regeneration step (Reg 1).

[0088] Figure 2 (Fresh catalyst), Figure 3 (Catalyst after the first regeneration) and Table 2 show that the selectivity of catalyst B for 1,3-butadiene is almost the same as that of catalyst A, which is produced with an ultra-pure silica support. In addition, the catalytic activity of catalyst B is higher, which advantageously leads to a higher 1,3-butadiene yield. In comparison, catalyst C (which contains higher amounts of both sodium and aluminum impurities) exhibits poor catalytic performance, i.e., lower selectivity for 1,3-butadiene and lower activity, resulting in a low 1,3-butadiene yield. Moreover, catalyst C has a higher selectivity for unwanted C6+ products (i.e., by-products containing 6 or more carbon atoms).

Claims

1. A supported catalyst, which comprises (i) a support, and (ii) with Ta 2 O 5 calculated and based on the total weight of the catalyst, 0.1 to 10% by weight of tantalum, wherein the supported catalyst further comprises 5 - 60 ppm of aluminum based on the total weight of the catalyst and 35 - 75 ppm of sodium based on the total weight of the catalyst.

2. The supported catalyst according to claim 1, wherein the support comprises one or more of an ordered and disordered porous silica support, other porous oxide supports, and mixtures thereof, preferably selected from ZrO 2 , TiO 2 , MgO, ZnO, NiO, and CeO 2 .

3. The supported catalyst according to claim 1 or 2, wherein the supported catalyst has a BET specific surface area in the range of 130 to 550 m 2 / g, preferably in the range of 190 to 280 m 2 / g.

4. The supported catalyst according to any one of the preceding claims, wherein the weight ratio of aluminum to sodium is in the range of 0.06 to 1.71, preferably in the range of 0.10 to 1.

0.

5. A catalyst reaction tube for producing 1,3 - butadiene, which comprises at least one packed bed of the supported catalyst as defined in any one of claims 1 to 4 and one or more packed beds of inert materials.

6. A reactor for producing 1,3 - butadiene, which comprises one or more catalyst reaction tubes as defined in claim 5.

7. A production facility for producing 1,3 - butadiene, which comprises one or more reactors as defined in claim 6, and means for regenerating the supported catalyst in the one or more reactors, preferably, wherein the production facility further comprises a pre - reactor for producing acetaldehyde having one or more reaction tubes, the pre - reactor containing a supported or unsupported (bulk) catalyst, the supported or unsupported (bulk) catalyst comprising one or more of zinc, copper, silver, chromium, magnesium and nickel.

8. A method for producing 1,3 - butadiene, the method comprises: (i) contacting a feed containing ethanol and acetaldehyde with the supported catalyst as defined in any one of claims 1 to 4 to obtain a crude product containing 1,3 - butadiene.

9. The method according to claim 8, wherein the contacting in (i) is carried out at a temperature of 200 - 500 °C, preferably 250 - 450 °C, more preferably 300 - 400 °C.

10. The method according to claim 8 or 9, wherein the contacting in (i) is carried out at a weight hourly space velocity in the range of 0.2 to 10 h -1 , preferably 1 to 7 h -1 and within the range of 11. The method according to any one of claims 8 to 10, wherein the contacting in (i) is carried out at a pressure in the range of 0 to 10 bar, preferably 1 to 3 bar.

12. The method according to any one of claims 8 to 11, further comprises (ii) separating the crude product into at least a first part containing 1,3 - butadiene, a second part containing acetaldehyde and a third part containing ethanol, preferably, wherein at least a part of the second part, at least a part of the third part or at least a part of both the second part and the third part is recycled to the feed.

13. The method according to any one of claims 8 to 12, wherein the contacting in (i) is carried out in the reactor as defined in claim 6 in the form of a continuous flow of the feed.

14. A method for producing the supported catalyst as defined in any one of claims 1 to 4, which comprises the following steps or consists of the following steps consisting of: (i) impregnating a support having an aluminum and sodium content defined by the following formula based on the weight of the catalyst support with a tantalum precursor solution to form a supported tantalum catalyst precursor, The lower limit is defined as follows: carrier [M] LL = catalyst [M] LL / (1 - catalyst [Ta 2 O 5 wt%), where M = Na or Al; where catalyst [Na] LL = 35 ppm and catalyst [Al] LL = 5 ppm; and The upper limit is defined as follows: carrier [M] UL = catalyst [M] UL / (1 - catalyst [Ta 2 O 5 wt%), where M = Na or Al; where catalyst [Na] UL = 75 ppm and catalyst [Al] UL = 60 ppm; (ii) drying the supported tantalum catalyst precursor, and (iii) calcining the dried supported tantalum catalyst precursor to form a supported tantalum catalyst.

15. The method for producing a supported catalyst according to claim 14, wherein the supported catalyst is a silica-supported catalyst, and the method comprises or consists of the following steps: (i) Reacting an aqueous silicate solution, preferably an aqueous sodium silicate solution, with an acid to form a hydrosol, (ii) Dispersing and gelling the hydrosol to form hydrogel beads, (iii) One or more optional additional steps of (pre)-aging, acidification, washing, and pH adjustment, a. Aging the hydrogel beads at a temperature T1, b. Acidifying the aged hydrogel beads, c. Washing the aged and acidified hydrogel beads, preferably with deionized water acidified to a pH of 3-4, d. Adjusting the pH of the washed hydrogel beads obtained in step (c), preferably to a pH in the range of about 8 to 10, (iv) Aging the hydrogel beads at a temperature T2, where T2>T1, (v) Acidifying the aged hydrogel beads, (vi) Washing the aged and acidified hydrogel beads, preferably with deionized water acidified to a pH of 3-4, (vii) Optionally adjusting the pH of the washed hydrogel beads obtained in step (vi), (viii) Drying the washed hydrogel beads obtained in step (vi) or (vii) to obtain a silica support, (ix) Optionally, sieving the silica support obtained in step (viii), (x) Impregnating the silica support obtained in step (viii) or (ix) with a solution of a tantalum precursor to form a supported tantalum catalyst precursor, (xi) Drying the supported tantalum catalyst precursor, and (xii) Calcining the dried supported tantalum catalyst precursor to form a supported tantalum catalyst.

16. Use of a supported catalyst as defined in any one of claims 1 to 4 for the production of 1,3-butadiene from a feed comprising ethanol and acetaldehyde, preferably for increasing the yield of 1,3-butadiene.

17. Use of sodium in an amount in the range of 35-75 ppm based on the total weight of the catalyst in a supported catalyst for the production of 1,3-butadiene from a feed comprising ethanol and acetaldehyde, for increasing the yield of 1,3-butadiene, the catalyst comprising - a support, - aluminum in an amount of 5 to 60 ppm based on the total weight of the catalyst, - Ta 2 O 5 calculated and based on the total weight of the catalyst, 0.1 to 10% by weight of tantalum.

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