CATALYST FOR THE PRODUCTION OF 1,3-BUTADIENE COMPRISING AN ALUMINIUM-CONTAINING SUPPORT WITH HIGH FAVORABLE WEIGHT HOURLY SPACE VELOCITY

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 1 to 50 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 1,3-butadiene productivity of the catalyst.

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 aluminium in a range of from 50 to 350 ppm, based on the total weight of the catalyst, and sodium in a range of from 1 to 50 ppm, 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, selected 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.

4. The supported catalyst according to claim 1, wherein the weight ratio of aluminium to sodium is in a range of from 1.0 to 350.

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, configured to regenerate the supported catalyst in said one or more reactors, preferably wherein the plant a se further 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.

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.

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.

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 for the production of 1,3-butadiene comprising one or more catalyst reaction tubes for the production of 1,3-butadiene comprising at least one packing of the supported catalyst and one or more packings of inert material.

14. A process for the production of the supported catalyst as defined in claim 1 comprising 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/(1-Catalyst [Ta.sub.2O.sub.5] wt. %), with M=Na or Al; where Catalyst [Na].sub.LL=1 ppm and Catalyst [Al].sub.LL=50 ppm; and the upper limit is defined by: Support [M].sub.uL=Catalyst [M].sub.uL/(1-Catalyst [Ta.sub.2O.sub.5] wt. %), with M=Na or Al; where Catalyst [Na].sub.uL=50 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: (i) reacting an aqueous 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 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), to a pH in a range 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 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. A method of using the supported catalyst as defined in claim 1 for the production of 1,3-butadiene from a feed comprising ethanol and acetaldehyde.

17. A method of using 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, 1 to 50 ppm of sodium, based on the total weight of the catalyst, 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 1,3-butadiene productivity of the catalyst.

Description

EXAMPLES

1. Silica Support Preparation

[0100] 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.

[0101] 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 250 ppm 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.

[0102] 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 a pH of about 9 for about 16 hours.

[0103] 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 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.

[0104] 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.

[0105] 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

[0106] 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.

[0107] 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:

[0108] 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). In general, 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. 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, 17 ppm Na and 225 ppm Al.

[0109] 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]$\mathrm{Support}\left[M\right]=\mathrm{Catalyst}\left[M\right]/(1-\mathrm{Catalyst}\left[{\mathrm{Ta}}_2{O}_5\right]\mathrm{wt}.\%,\mathrm{with}M=\mathrm{Na}\mathrm{or}\mathrm{Al}$

[0110] Consequently, the Na and Al in the support are calculated to be 17.6 ppm and 232 ppm respectively.

[0111] Data related to the catalysts synthesized according to the above procedures are summarized in Table 1 below.

TABLE-US-00001 TABLE 1 Data on Catalysts A and B Sample Type Catalyst A Catalyst B Ta [wt %] 2.56 2.71 Ta.sub.2O.sub.5 [wt %] 3.1 3.3 Na [ppm] 31 17 Al [ppm] 6 225 BET specific surface area [m.sup.2/g] 252 253 Pore volume [cm.sup.3/g] 0.95 1.02 Average pore diameter [] 151 162

3. Sodium and Aluminium Analysis Method

[0112] The levels of sodium and aluminium in the catalyst compositions were measured by Atomic Absorption Spectroscopy (AA) using a Perkin-Elmer PinAAcle 900F 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

[0113] 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.

[0114] The physico-chemical properties of the catalysts synthesized according to the above procedure are summarized in Table 2 below.

TABLE-US-00002 TABLE 2 Physico-chemical properties of the catalysts Average BET specific pore Ta.sub.2O.sub.5 Ta Al Na surface area diameter content content content content Catalyst [m.sup.2/g] [] [wt. %] [wt. %] [ppm] [ppm] A 252 151 3.1 2.6 6 31 B 253 162 3.3 2.7 225 17

5. Catalytic Tests

[0115] 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), at a pressure of 1.8 barg and with a WHSV as indicated below (cf. e.g. Table 3). 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).

[0116] Catalysts lose their activity for the production of 1,3-butadiene during the operation and require regeneration. Catalyst regeneration was carried out after 100 hours (h) time on stream (TOS) in situ in the stainless steel reactor, in the following four stages. [0117] 1. Desorption and removal of organic vapors [0118] 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. [0119] 2. Preliminary combustion of carbon deposits [0120] 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. [0121] 3. Combustion of carbon deposits [0122] 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. %. [0123] 4. Cooling down [0124] The reactor was cooled down to 350 C., in a nitrogen flow (GHSV=300 h.sup.1).

[0125] Total conversion, selectivity, yield, and productivity were calculated as shown below (EtOH=ethanol; AcH=acetaldehyde):

[00003]$\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{of}1.3-\mathrm{butadiene}}{\mathrm{mass}\mathrm{of}\mathrm{catalyst}}$

[0126] The average results of the catalytic tests of the fresh (non-regenerated) catalysts are summarized in Table 3 below. Catalyst B according to the invention shows a lower total conversion when compared to catalyst A when both catalysts are tested at their respective favourable WHSV conditions (cf. column WHSV in Table 3), however, it was found that its favourable WHSV conditions are at a significantly higher level compared to catalyst A. Thus, the 1,3-butadiene productivity of the catalyst is surprisingly markedly increased for catalyst B according to the invention, as compared to catalyst A (cf. also FIG. 2, which shows that, for catalyst B, both 1,3-butadiene productivity and selectivity to 1,3-butadiene increase as WHSV is increased from 2 h.sup.1 to 5 h.sup.1).

TABLE-US-00003 TABLE 3 Results of the catalytic tests (average results for fresh catalysts with a TOS = 100 h); Selectivity Total to 1,3- Yield of 1,3-Butadiene WHSV Conver- Butadiene Selectivity 1,3-Buta- productivity Catalyst [h.sup.1] sion [%] [%] to C6+ [%] diene [%] [g.sub.1,3-BD/(g.sub.cat .Math. h)] A 5 26 70 10 18.2 0.59 A 2.3(*) 48 72 10 34.6 0.48 B 5 33 75 7 24.8 0.76 ggrams; hhour; 1,3-BD1,3-butadiene; catcatalyst

[0127] The impact of the impurity content of the fresh catalysts is further depicted over the course of 100 hours TOS in FIG. 3. Again, catalyst B according to the invention is compared to catalyst A in the catalytic tests as described above. Catalyst A was tested both at its favourable WHSV of 2.3 h.sup.1 (*) and at a WHSV of 5 h.sup.1, and catalyst B was tested at a WHSV of 5 h.sup.1. As shown in FIG. 3, the selectivity to 1,3-butadiene is higher for catalyst B at a WHSV of 5 h.sup.1 than for catalyst A at both a WHSV of 2.3 h.sup.1 and 5 h.sup.1. Moreover, lower selectivity to heavy compounds (C6+=side products containing 6 or more carbon atoms) as side-products leads to a more stable selectivity to 1,3-butadiene during time on stream (TOS) for catalyst B.

[0128] FIG. 4 further shows the performance of catalysts A and B over the course of 100 hours TOS after five regeneration cycles, respectively. Again, catalyst A was operated at its favourable WHSV of 2.3 h.sup.1 (*) and catalyst B was operated at its favourable WHSV of 5 h.sup.1. As can be taken from FIG. 4, the selectivity to 1,3-butadiene is higher during the first couple of hours for catalyst A, but it decreases slowly with time on stream (TOS). Catalyst B, even though it shows lower selectivity to 1,3-butadiene in the beginning of this experiment, advantageously stabilizes at the levels reached by the catalyst A and shows better stability and higher selectivity to 1,3-butadiene in the last 50 hours on stream. Again, a lower selectivity to heavy compounds (C6+) as side-products is observed for catalyst B according to the invention through the entire course of the experiment.