CATALYST FOR THE PRODUCTION OF 1,3-BUTADIENE GIVING A HIGH YIELD BASED ON A SUPPORT COMPRISING ALUMINIUM AND SODIUM

Abstract

The present invention relates to a supported catalyst comprising a support and 0. 1 to 10 wt. % of tantalum, calculated as Ta.sub.2O.sub.5 and based on the total weight of the catalyst. wherein the supported catalyst further comprises from 50 to 350 ppm of aluminium and from 300 to 500 ppm of sodium, based on the total weight of the catalyst, respectively. Moreover, the invention relates to a catalyst reaction tube for the production of 1,3-butadiene comprising at least one packing of the supported catalyst as defined herein, to a reactor for the production of 1,3-butadiene comprising one or more of the catalyst reaction tubes as defined herein, and to a plant for the production of 1,3-butadiene comprising one or more of the reactors as defined herein. The invention also relates to a process for the production of 1,3-butadiene as defined herein and to a process for the production of the supported catalyst as defined herein. Finally, the present 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 aluminium in an amount in a range of from 50 to 350 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.

Claims

1. A supported catalyst comprising (i) a support, and (ii) 0.1 to 10 wt % of tantalum, calculated as Ta.sub.2O.sub.5 and based on the total weight of the catalyst, wherein the supported catalyst further comprises from 50 to 350 ppm of aluminium, based on the total weight of the catalyst, and from 300 to 500 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 ordered and non-ordered porous silica supports, other porous oxide supports and mixtures thereof, preferably from ZrO.sub.2, TiO.sub.2, MgO, ZnO, NiO, and CeO.sub.2.

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

4. The supported catalyst according to claim 1, wherein the weight ratio of aluminium to sodium is in a range of from 0.1 to 1.2, preferably 0.2 to 1.0.

5. A catalyst reaction tube for the production of 1,3-butadiene comprising at least one packing of the supported catalyst as defined in claim 1 and one or more packings of inert material.

6. A reactor for the production of 1,3-butadiene comprising one or more of the catalyst reaction tubes as defined in claim 5.

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

8. A process for the production of 1,3-butadiene, the process comprising (i) contacting a feed comprising ethanol and acetaldehyde with the supported catalyst as defined in claim 1 to obtain a raw product comprising 1,3-butadiene.

9. The process according to claim 8, wherein the (i) contacting takes place at a temperature in a range of from 200 to 500 C., preferably from 250 to 450 C., more preferably from 300 to 400 C.

10. The process according to claim 8, wherein the (i) contacting takes place at a weight hourly space velocity in a range of from 0.2 to 10 h.sup.1, preferably from 1 to 7 h.sup.1.

11. The process according to claim 8, wherein the (i) contacting takes place at a pressure in a range of from 0 to 10 barg, preferably from 1 to 3 barg.

12. The process according to claim 8, further comprising (ii) separating the raw product at least into a first portion comprising 1,3-butadiene, a second portion comprising acetaldehyde and a third portion comprising ethanol, preferably wherein at least part of the second, of the third, or of both the second and of the third portions is recycled into the feed.

13. The process of claim 8, wherein the (i) contacting takes place in a continuous flow of the feed in a reactor.

14. A process for the production of the supported catalyst as defined in claim 1 comprising or consisting of the following steps: (i) impregnation of the support with aluminium and sodium levels defined by the formulas below based on the weight of the catalyst support, with a solution of a tantalum precursor, to form a supported tantalum catalyst precursor, wherein the lower limit is defined by: Support [M].sub.LL=Catalyst [M].sub.LL/(1Catalyst [Ta.sub.2O.sub.5] wt. %), with M=Na or Al; where Catalyst [Na].sub.LL=300 ppm and Catalyst [Al].sub.LL=50 ppm; and the upper limit is defined by: Support [M].sub.UL=Catalyst [M].sub.UL/(1Catalyst [Ta.sub.2O.sub.5] wt. %), with M=Na or Al; where Catalyst [Na].sub.UL=500 ppm and Catalyst [Al].sub.UL=350 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 process for the production of the supported catalyst as defined in claim 14, wherein the supported catalyst is a silica supported catalyst and the method comprises or consists of: (i) reacting an aqueous silicate, preferably sodium silicate, solution with an acid to form a hydrosol, (ii) dispersion and gelation of the hydrosol to form hydrogel beads, (iii) one or more optional additional steps of (pre-) aging, acidification, washing and pH adjustment, a. aging of the hydrogel beads at temperature T1, b. acidification of the aged hydrogel beads, c. washing, preferably with water that is deionized and acidified to pH 3-4, of the acidified aged hydrogel beads, d. adjusting the pH of the washed hydrogel beads obtained in step (c), preferably to a pH of about 8-10, (iv) aging of the hydrogel beads at temperature T2, with T2>T1, (v) acidification of the aged hydrogel beads, (vi) washing, preferably with water that is deionized and acidified to pH 3-4, of the acidified aged hydrogel beads, (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 of the silica support obtained in step (viii), (x) impregnation of 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 the supported catalyst as defined in claim 1 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 aluminium in an amount in a range of from 50 to 350 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, the catalyst comprising a support, 300 to 500 ppm of sodium, based on the total weight of the catalyst, and 0.1 to 10 wt. % of tantalum, calculated as Ta.sub.2O.sub.5 and based on the total weight of the catalyst, for increasing the yield of 1,3-butadiene.

Description

EXAMPLES

1. Silica Support Preparation

[0093] The following is a description of the general steps used for making the silica support according to an embodiment of the present disclosure. A flow chart showing the general steps used in making silica support according to an embodiment of the present disclosure is provided in FIG. 1. A more detailed description of the silica support and methods of making it are found in co-pending application number U.S patent application Ser. No. 16/804,610, which is herein incorporated by reference.

[0094] In one embodiment, a dilute sodium silicate solution of 3.3 weight ratio SiO.sub.2:Na.sub.2O was first reacted with dilute sulfuric acid, to form a hydrosol having the following composition: 12 wt. % SiO.sub.2 and H.sub.2SO.sub.4:Na.sub.2O in a molar ratio of 0.8. As a result, the resulting hydrosol was basic. In one embodiment, the sodium silicate solution contained approximately 250ppm aluminium on SiO.sub.2 weight basis. In one embodiment, a higher purity silicate with low aluminium (<10 ppm on SiO.sub.2 weight basis) was used to make silica with lower aluminium content.

[0095] The hydrosol was then sprayed into air, where it broke into droplets and solidified into beads having a diameter of several millimeters before it was caught in a solution such as water or a solution that buffers the pH of the beads/solution system at a basic pH of about 9 (such as aqueous solution of ammonium sulfate, sodium bicarbonate, etc.). Higher aging temperature and/or longer aging times reduces the silica surface area. Generally, for hydrogel caught in ammonium sulfate solution to achieve a surface area of about 300 m.sup.2/g, aging is conducted at 70 C. at pH about 9 for about 16 hours.

[0096] Acid was then added to lower the pH to about 2. The hydrogel beads were then washed with water that was acidified to a pH of about 3 to reduce sodium levels. The aged and washed hydrogel beads contain about 15-18% SiO.sub.2. Once washed, the pH of the beads was increased to about 9 using ammonium hydroxide solution. The beads were then dried using an oven. Finally, the beads were sieved to get the desired particle size fraction. Note that pH adjustment before drying is optional, and beads are typically dried from pH 3-9.

[0097] In one embodiment, the described process can be modified to optionally include multiple aging steps at increasing temperatures with each aging step followed by acidification and washing steps to get the desired combination of surface area and sodium levels. In one embodiment, optionally, washing can be done before the aging step.

[0098] Following the procedure outlined above, one can obtain a silica gel bead with a surface area of about 230-300 m.sup.2/g, a pore volume of about 0.95-1.05 cm.sup.3/g, aluminium <500 ppm (depending on silicate purity and/or the process and conditions used to carry out the washing and aging steps), and sodium <1000 ppm (depending on extent of washing in combination with multiple aging steps). In some cases, the silica hydrogel containing low amounts of aluminium and/or sodium (on dry basis) were contacted with a solution of aluminium sulfate and/or sodium carbonate respectively before drying to adjust aluminium and/or sodium to desired levels.

2. Catalyst Preparation

[0099] In all cases the silica gel beads with size 2-5 mm were pre-dried to a loss of drying (LOD) <0.5 wt. %, measured at 120 C., before use. The following is a general description of making the catalyst on a basis of using 100 g silica support on dry basis. Broadly, the tantalum precursor was added to the silica via the incipient wetness impregnation method.

[0100] For every 100 g (dry basis) of silica gel support, a stabilized tantalum precursor solution was made by mixing approximately 5-6 g of tantalum precursor, such as 5.7 g tantalum ethoxide with 2-3 g, such as 2.8 g of 2,4-pentanedione (acetyl acetone). In general, 8.5 g of the stabilized tantalum precursor solution was dissolved in 65-76 g isopropanol, which was then added on to the pre-dried silica gel beads. The amount of isopropanol was adjusted based on the support pore volume, so that the solution was contained only in the silica pores, and there was no free solution outside the pores. Impregnation took around 15-40 minutes. The impregnated silica gel was kept in a sealed container for at least 1 hour before the solvent was evaporated by heating at atmospheric pressure or under vacuum. The dried material was then calcined up to 550 C. for 4 hours in air to give the finished catalyst with approximately 3.0 wt. % Ta.sub.2O.sub.5. In one embodiment, Catalyst A was made using this preparation method.

Preparation of Catalyst B:

[0101] Silica gel beads with size 2-5 mm were pre-dried to a loss of drying (LOD)<0.5 wt. %, measured at 120 C., before use. For 100 g (dry basis) of silica gel support, a stabilized tantalum precursor solution was made by mixing 5.7 g tantalum ethoxide with 2.8 g of 2,4-pentanedione (acetyl acetone). 8.5 g of the stabilized tantalum precursor solution was dissolved in 73 g isopropanol, which was then added on to the pre-dried silica gel beads. Impregnation took around 15-40 minutes. The impregnated silica gel was kept in a sealed container for at least 1 hour before the solvent was evaporated by heating at atmospheric pressure. The dried material was then calcined up to 550 C. for 4 hours in air to give the finished catalyst with 2.9 wt. % Ta.sub.2O.sub.5, 372 ppm Na and 8 ppm Al.

[0102] The Na and Al can be assumed to be present in the support since no substantial quantities of Na or Al are present in the Ta-ethoxide, acetyl acetone or isopropanol. The amount of Na or Al in the support and catalyst is then related by the formula:

[00002]$\mathrm{Support}\left[M\right]=\mathrm{Catalyst}\left[M\right]/\left(1-\mathrm{Catalyst}\left[{\mathrm{Ta}}_2{O}_5\right]\mathrm{wt}.\%\right),\mathrm{with}M=\mathrm{Na}\mathrm{or}\mathrm{Al}$

[0103] Consequently, the Na and Al in the support are calculated to be 383 ppm and 8.2 ppm respectively.

Preparation of Catalyst C:

[0104] Silica gel beads with size 2-5 mm were pre-dried to a loss of drying (LOD)<0.5 wt. %, measured at 120 C., before use. For 100 g (dry basis) of silica gel support, a stabilized tantalum precursor solution was made by mixing 5.7 g tantalum ethoxide with 2.8 g of 2,4-pentanedione (acetyl acetone). 8.5 g of the stabilized tantalum precursor solution was dissolved in 70 g isopropanol, which was then added on to the pre-dried silica gel beads.

[0105] Impregnation took around 15-40 minutes. The impregnated silica gel was kept in a sealed container for at least 1 hour before the solvent was evaporated by heating at atmospheric pressure. The dried material was then calcined up to 550 C. for 4 hours in air to give the finished catalyst with 3.3 wt. % Ta.sub.2O.sub.5, 392 ppm Na and 230 ppm Al.

[0106] The Na and Al can be assumed to be present in the support since no substantial quantities of Na or Al are present in the Ta-ethoxide, acetyl acetone or isopropanol. The amount of Na or Al in the support and catalyst is then related by the formula:

[00003]$\mathrm{Support}\left[M\right]=\mathrm{Catalyst}\left[M\right]/\left(1-\mathrm{Catalyst}\left[\mathrm{Ta}2O5\right]\mathrm{wt}.\%\right),\mathrm{with}M=\mathrm{Na}\mathrm{or}\mathrm{Al}$

[0107] Consequently, the Na and Al in the support are calculated to be 405 ppm and 238 ppm respectively.

TABLE-US-00001 TABLE 1 Data on Catalysts A, B and C Catalyst Catalyst Catalyst Sample Type A B C Ta [wt %] 2.56 2.37 2.71 Ta.sub.2O.sub.5 [wt %] 3.1 2.9 3.3 Na [ppm] 31 372 392 Al [ppm] 6 8 230 BET SSA [m.sup.2/g] 252 271 252 PV [cm.sup.3/g] 0.95 1.02 1.01 APD [] 151 150 160

3. Sodium and Aluminium Analysis Method

[0108] The levels of sodium and aluminium in the catalyst compositions were measured by Atomic Absorption Spectroscopy (AA) using a Perkin-Elmer PinAAcle900F Spectrometer and Inductively Coupled Plasma (ICP) Spectroscopy using a Perkin Elmer Optima 8300 ICP-OES spectrometer, respectively. Samples of catalyst were digested with hydrofluoric acid (HF). The resulting silicon tetrafluoride (SiF.sub.4) was fumed away and the residue was analyzed for sodium and aluminium. Sodium and aluminium levels are reported as the parts per million of the catalyst after drying at 120 C. The sodium and aluminium amounts of the support and the tantalum starting material, respectively, can be determined accordingly if desired.

4. Tantalum Analysis Method

[0109] The levels of tantalum in the catalyst compositions were measured by Inductively Coupled Plasma (ICP) Spectroscopy using a Perkin Elmer Optima 8300 ICP-OES spectrometer. Samples of catalyst were digested with hydrofluoric acid (HF). The resulting silicon tetrafluoride (SiF.sub.4) was fumed away and the residue was analyzed for tantalum. Results are reported on dried weight basis of the catalyst calcined at 500 to 550 C.

5. Catalytic Tests

[0110] 40 grams of the catalysts synthesized according to the above procedure were placed into a respective continuous flow-operated stainless steel reactor. The reactor had initially been heated to 350 C., at a nitrogen flow rate of 500 ml/min. (Nitrogen was used only when heating the reactor, whereas the reaction was carried out without nitrogen flow, but solely with the indicated organic feed.) The reaction was then carried out using 94 wt. % aqueous ethanol mixed with acetaldehyde at a mass ratio of 2.5:1 as a feed (the mass portion of 2.5 for the 94 wt. % aqueous ethanol relates to the combined weight of water and ethanol), with a weight hourly space velocity (WHSV) of 5.0 h.sup.1 and at a pressure of 1.8 barg. The composition of the effluent was regularly monitored by an online gas chromatograph equipped with a flame-ionization detector coupled with a mass spectrometer (GC/MS).

[0111] Catalysts lose their activity for the production of 1,3-butadiene during the operation and require regeneration. Catalyst regeneration was carried out after 110 hours (h) time on stream (TOS) in situ in the stainless steel reactor, in the following four stages. [0112] 1. Desorption and removal of organic vapors [0113] Organic vapors were removed by purging with a stream of nitrogen (gas hourly space velocity (GHSV)=300 h.sup.1) at 350 C. for 5 hours. [0114] 2. Preliminary combustion of carbon deposits [0115] Deposits were burnt in a stream of air diluted by steam (GHSV=300 h.sup.1) for 15 hours. The oxygen content in the regeneration mixture (air/steam) was gradually increased from 1 to 6 vol. %, so that the temperature in the reactor would not exceed 400 C. [0116] 3. Combustion of carbon deposits

[0117] The temperature of the reactor was increased to 520 C. Deposits were finally burnt in a stream of air diluted by nitrogen (GHSV=300 h.sup.1) for 20 hours. The oxygen content in the regeneration mixture (air/nitrogen) was 6 vol. %. [0118] 4. Cooling down [0119] The reactor was cooled down to 350 C., in a nitrogen flow (GHSV=300 h.sup.1).

[0120] Total conversion, selectivity, yield, and productivity were calculated as shown below (EtOH=ethanol; AcH=acetaldehyde):

[00004]$\mathrm{Total}\mathrm{Conversion}=\frac{\mathrm{moles}\mathrm{of}\mathrm{converted}\mathrm{EtOH}\mathrm{and}\mathrm{AcH}}{\mathrm{moles}\mathrm{of}\mathrm{EtOH}\mathrm{and}\mathrm{AcH}\mathrm{in}\mathrm{the}\mathrm{feed}}.Math.100$$\mathrm{Selectivity}=\frac{C\mathrm{moles}\mathrm{in}1,3-\mathrm{butadiene}}{C\mathrm{moles}\mathrm{in}\mathrm{all}\mathrm{products}}.Math.100$$\mathrm{Yield}=\frac{\mathrm{Total}\mathrm{Conversion}.Math.\mathrm{Selectivity}}{100}$$\mathrm{Productivity}=\frac{\mathrm{mass}\mathrm{flow}\mathrm{rate}\mathrm{of}1,3-\mathrm{butadiene}}{\mathrm{mass}\mathrm{of}\mathrm{catalyst}}$

TABLE-US-00002 TABLE 2 Overview over physico-chemical properties of the fresh (i.e. non-regenerated) catalysts synthesized according to the above procedure and their performance in 1,3-butadiene synthesis according to example 4 Productivity of Total Selectivity to 1,3-BDN Conversion [%].sup.b 1,3-BDN [%].sup.b Yield [%].sup.b [g.sub.1,3-BDN/(g.sub.cat .Math. h)].sup.b BET Al Na (gain/loss in (gain/loss in (gain/loss in (gain/loss in SSA APD content content TOS comparison to comparison to comparison to comparison to Catalyst [m.sup.2/g] [] [ppm] [ppm] [h] reference) reference) reference) reference) A.sup.a 252 151 6 31 100 26.3 71.3 18.8 0.59 B 271 150 8 372 100 27.7 65.8 18.2 0.58 (+5%) (8%) (3%) (2%) C 252 160 230 392 100 27.6 69.1 19.1 0.60 (+5%) (3%) (+2%) (+2%) (.sup.areference; .sup.bin average for a given time on stream; BET SSABET specific surface area; APDaverage pore diameter; Alaluminium; Nasodium; TOStime on stream; EtOHethanol; AcHacetaldehyde; 1,3-BDN1,3-butadiene; ggrams; hhour; catcatalyst; process conditions: catalysts Ta.sub.2O.sub.5SiO.sub.2 (ca. 2.5 wt. % of tantalum as Ta, dry basis; 3.1 wt % as Ta.sub.2O.sub.5), 94 wt. % EtOH:AcH = 2.5:1 wt./wt.; WHSV 5 h.sup.1; 350 C., 1.8 barg)

[0121] The results of the catalytic test of catalyst B (not according to the invention) in Table 2 show that an increase in sodium level increases the total conversion compared to ultra pure catalyst A (not according to the invention), however, it has a strongly detrimental effect on the selectivity to 1,3-butadiene. Thus, both the achieved yield and productivity of 1,3-butadiene are lower for catalyst B compared to catalyst A.

[0122] The results of the catalytic test of catalyst C (according to the invention) in Table 2 demonstrate that a simultaneous increase in aluminium level surprisingly offsets the detrimental effects of the increased sodium level. In the catalytic test of catalyst C not only the total conversion was increased, but also the selectivity loss to 1,3-butadiene was small, so that overall an increase in both yield and productivity of 1,3-butadiene was advantageously achieved with the catalyst according to the invention.