Method for producing a metal-containing shell catalyst without intermediate calcining

Abstract

A method for producing a shell catalyst which comprises, in the outer shell, one or more of the following metals: Pd, Pt, Ag and Au. Also the use of the shell catalyst produced using the method according to the invention for the production of vinyl acetate monomer, in the hydrogenation of hydrocarbons, in particular the selective hydrogenation of polyunsaturated hydrocarbon compounds, or in the oxidation of alcohols to ketones/aldehydes/carboxylic acids.

Claims

1. A method for producing a shill catalyst, comprising the steps of mixing one or more support bodies by a controlled glide layer consisting of one of air and inert gas; during the mixing, spraying the one or more support bodies with a first solution comprising a substantially chloride-free Pd-, Pt-, Ag- or Au-containing first precursor compound, and subjecting the one or more support bodies to a first temperature treatment in the range of from 80° C to 500° C in a non-oxidizing atmosphere.

2. The method according to claim 1, wherein, before or after the first temperature treatment, the one or more support bodies are mixed by a controlled glide layer comprising at least one of air and inert gas, and, during the mixing, frayed with a second solution comprising a second substantially chloride-free Pd-, Pt-, Ag- or Au-containing precursor compound.

3. The method according to claim 2, wherein the first precursor compound and the second precursor compound form the following pairs: (a) Pd-containing precursor compound and Au-containing precursor compound; (b) Pt-containing precursor compound and Au-containing precursor compound; (c) Pd-containing precursor compound and Ag-containing precursor compound; (d) Pt-containing precursor compound and Ag-containing precursor compound; (e) Ag-containing precursor compound and Au-containing precursor compound; or (f) Pd-containing precursor compound and Pt-containing precursor compound.

4. The method according to claim 2, wherein the second precursor compound is applied after the temperature treatment, and the one or more support bodies with the applied second precursor compound is subjected to a second temperature treatment in the range of from 80° C. to 500° C. in a non-oxidizing atmosphere.

5. The method according to claim 4, wherein there is no intermediate calcining between the spraying of the one or more support bodies with the second solution and the second temperature treatment.

6. The method according to claim 2, wherein the first precursor compound is a Pd- or Pt-containing precursor compound, and the second precursor compound is an Au-containing precursor compound.

7. The method according to claim 6, wherein the Pd or Pt content lies in the range of from 0.3 to 2wt.-% relative to the total weight of the catalyst and the Au content lies in the range of from 0.1 to 0.9 wt.-% relative to the total weight of the catalyst.

8. The method according to claim 2, wherein the first precursor compound is a Pd- or Pt-containing precursor compound, and the second precursor compound is an Ag-containing precursor compound.

9. The method according to claim 8, wherein the Pd or Pt content lies in the range of from 100 to 300 ppm relative to all parts of the catalyst at and the Ag content lies in the range of from 400 to 600 ppm relative to all parts of the catalyst.

10. The method according to claim 2, wherein the first precursor compound is a Pd- or Pt-containing precursor compound and the second precursor compound is an Ag- or Au-containing precursor compound.

11. The method according to claim 10, wherein the Pd or Pt content lies in the range of from 3 to 7 wt.-% relative to the total weight of the catalyst and the Ag or Au content lies in the range of from 1 to 5 wt.-% relative to the total weight of the catalyst.

12. The method according to claim 1, wherein the Pd- and Pt-containing precursor compounds are independently selected from the group consisting of nitrate compounds, acetate compounds, tetraammine compounds, diamine compounds, hydrogen carbonate compounds and hydroxidic metallate compounds.

13. The method according to claim 1, wherein the Ag- and Au-containing precursor compounds are independently selected from the group consisting of acetate compounds, nitrite compounds and hydroxidic metallate compounds.

14. The method according to claim 1, wherein the non-oxidizing atmosphere of the first treatment and the second temperature treatment independently comprise an inert gas atmosphere or a reducing atmosphere.

15. The method according to claim 14, wherein the reducing atmosphere is formed by forming gas.

16. The method according to claim 14, wherein, during the first temperature or the second temperature treatment, a change from an inert gas atmosphere to a reducing atmosphere takes place.

17. The method according to claim 16, wherein the change from inert gas to a reducing atmosphere takes place by adding hydrogen gas to the inert gas.

18. The method according to claim 17, wherein the change from an inert gas atmosphere to a reducing atmosphere is carried out such that the temperature does not fall below 80° C during the change.

19. The method according to claim 1, wherein there is no intermediate calcining between the spraying of the one or more support bodies with the first solution and the first temperature treatment.

20. The method according to claim 1, wherein the one or more support bodies have a diameter, length or width in the range of from 1 to 10 mm.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 shows a diagram in which the vinyl acetate monomer selectivity of the tested catalysts is plotted on the Y-axis. The oxygen conversion of six tested catalysts is shown on the X-axis.

EXAMPLES

Comparison Example 1

Shell Catalyst A

(2) A shell catalyst A was produced in the following way: 1.2 litres of a silica support in spherical shape with a diameter of 5 mm, a density of 540 g/L, a pore volume of 0.68 ml/g and a pH of 4.0 in a 10 wt.-% suspension, was impregnated with 440 ml of an aqueous solution of Na.sub.2PdCl.sub.4 and HAuCl.sub.4 containing 3.96 g Pd and 1.8 g Au (99.8 of the absorption capacity of the support). A vessel containing this mixture was rotated mechanically until the solution was completely absorbed by the silica support. 500 ml of a solution containing 25.2 g Na.sub.2SiO.sub.3.9H.sub.2O was then added to the support, with the result that this was completely covered. This was left to stand for 12 hours at room temperature. After this time, the liquid surrounding the support had a pH of 7.7. 25 ml of an 85% hydrazine hydrate solution was then added, lightly mixed and the resulting mixture was left to stand for 4 hours at room temperature in order to reduce the palladium and gold. The catalyst was then washed three times with distilled water by decanting, followed by continuous washing over 16 hours at a washing rate of 1-2 litres distilled water per hour. After this period, the washing water was free of chlorides, which was proved by the absence of a precipitate when silver nitrate was added.

(3) The catalyst was then dried for 4 hours at 110° C., impregnated with a solution containing 36 g potassium acetate (corresponds to 30 g potassium acetate per litre catalyst) and dried again. The thus-obtained catalyst contained 3.32 g/l palladium and 1.39 g/l gold, compared with 3.3 g/l palladium and 1.5 g/l gold in the starting compounds. Thus, 100% palladium and 92.7% gold were precipitated.

Comparison Example 2

Shell Catalyst B

(4) The production of a shell catalyst B took place according to the following procedure: coating of 53.21 g of a 3.12% Pd(NH.sub.3).sub.4(OH).sub.2 solution onto 100 g KA-160 support spheres (manufacturer: Süd-Chemie AG) (standard conditions: 70° C. coating temperature, 2×1 tube, 80% spraying rate in the Innojet AirCoater 025), followed by intermediate calcining at 350° C. for 4 h in air, then coating-on of 14.66 g of a 7.54% KAuO.sub.2 solution, then drying in the fluidized bed at 90° C. for 45 min, then reduction with forming gas in the gas phase at 150° C. for 5 h, then IW (incipient wetness) impregnation with aqueous KOAc solution, and finally drying at 90° C. in the fluidized bed for 45 min.

Comparison Example 3

Shell Catalyst C

(5) The production of a shell catalyst C took place according to the following procedure: a catalyst precursor was produced analogously to Example 1, with the difference that reduction was in the gas phase with forming gas at 200° C. for 5 h and impregnation with KOAc had not yet taken place. This catalyst precursor was further processed as follows: coating-on of 8.61 g of a 7.54% KAuO.sub.2 solution, followed by reduction in the gas phase with forming gas at 150° C. for 5 h, then impregnation with KOAc by the incipient wetness method.

Comparison Example 4

Shell Catalyst D

(6) The production of a shell catalyst D took place according to the following procedure: coating of 35.20 g of a 3.12% Pd(NH.sub.3).sub.4(OH).sub.2 solution onto 100 g KA-160 support spheres, followed by drying in the fluidized bed at 90° C. for 45 min, then intermediate calcining at 350° C. for 4 h in air, then coating-on of 11.64 g of a 7.54% KAuO.sub.2 solution (not the standard conditions in the coater, but 60° C. coating temperature, 3×1 tube, 100% spraying rate), then drying in the fluidized bed at 90° C. for 45 min, then reduction with forming gas in the gas phase at 150° C. for 5 h, then IW (incipient wetness) impregnation with aqueous KOAc solution, and finally drying at 90° C. in the fluidized bed for 45 min.

Example 1 (According to the Invention)

Shell Catalyst E

(7) A mixed solution of 24.85 ml of a 4.4% Pd(NH.sub.3).sub.4(OH).sub.2 solution in 150 ml H.sub.2O and 5.74 ml of a 9.9% KAuO.sub.2 solution in 150 ml H.sub.2O is coated at 70° C. onto 100 g KA-160 supports (5 mm), followed by drying at 90° C. for 45 min in the fluidized bed and then reduction without intermediate calcining at 350° C. for 4 h with forming gas. IW (incipient wetness) impregnation with aqueous KOAc solution follows (16.79 g 2 molar KOAc was weighed in and topped up with water to 98% of the water absorption of the support for the incipient wetness impregnation (pore-filling method)) for 1 h in a rotating round-bottomed flask (Rotavapor) and the final drying in the fluidized bed at 90° C. for 45 min. The metal contents determined by chemical analysis (LOI-free) (LOI=loss on ignition) of the finished catalyst are 1.02% Pd and 0.57% Au.

Example 2

Results

(8) The results for the shell catalysts A to E as regards the selectivity for the synthesis of vinyl acetate as a function of the oxygen conversion are shown in FIG. 1 and Tables 1 and 2. For this, acetic acid, ethylene and oxygen were each passed over the catalysts A to E at a temperature of 140° C./12 h—>144° C./12 h—>148° C./12 h (these are the respective reaction temperatures that apply in turn during the automated execution of the screening protocol, i.e. measurement is carried out for 12 h at 140° C., then for 12 h at 144° C., and then for 12 h at 148° C. reactor temperature) and a pressure of 7 bar. The concentrations of the components used were: 39% ethylene, 6% O.sub.2, 0.6% CO.sub.2, 9% methane, 12.5% acetic acid, remainder N.sub.2.

(9) The formed vinyl acetate is isolated with the help of suitable methods, which are described for example in U.S. Pat. No. 5,066,365 A.

(10) TABLE-US-00001 TABLE 1 Catalyst A Catalyst B Catalyst C VAM selectivity VAM selectivity VAM selectivity from VAM and O2 conversion from VAM and O2 conversion from VAM and O2 conversion CO2 peaks [%] [%] CO2 peaks [%] [%] CO2 peaks [%] [%] 94.5403736 33.38043263 92.8868103 36.41085397 93.93080782 46.2697302 94.54486515 33.73055667 92.50913818 44.86784605 93.62038499 55.25321859 94.58527534 34.01582915 92.57239016 44.88278355 93.52413305 54.57788196 94.43825207 33.10042502 92.62715235 44.5457634 93.64021575 54.58827647 93.64638431 39.03542836 92.65624986 43.99216432 93.7488175 54.43298037 93.73965914 39.12083312 92.97857691 43.81941636 93.69595227 53.33102061 93.77144861 39.02310831 92.65806345 42.62705498 93.66026672 52.87150042 93.78511742 38.83466548 91.22106445 50.47282872 92.65953438 62.01286258 93.95832411 39.18493382 91.43004144 49.99063328 92.83067608 62.16211753 93.86783871 38.08404005 91.67029341 49.50882991 92.85039609 61.26118317 91.66434729 48.24962899 93.06248463 61.09097702 91.96231232 48.16275199 93.04816286 60.63690859 92.00149982 47.28660329 93.12556275 59.99297675 92.12220312 46.79208048 93.0977835 59.6039523 94.40299741 33.38791913 94.90113926 42.7573582 94.78763983 33.93667492 95.15124024 42.84849106 94.59378223 32.85605593 94.96082578 42.12923203 94.65897141 32.98446753 94.96251057 41.82625695 94.52912807 32.25492922 94.91608119 41.68556177 94.41133174 31.36055782 94.67162429 40.35968328

(11) TABLE-US-00002 TABLE 2 Catalyst D Catalyst E VAM selectivity VAM selectivity from VAM and O2 conversion from VAM and O2 conversion CO2 peaks [%] [%] CO2 peaks [%] [%] 92.11570687 55.16832068 95.16626159 51.31941346 92.54403671 55.91630926 94.60282084 60.82778578 91.10913177 66.69895594 99.00530146 54.54899079 91.34254639 66.13532853 94.6888208 60.19573635 91.45795194 65.43206064 94.65323656 59.67685586 91.53140581 64.5682873 94.67307711 59.19945111 91.63454785 63.44787341 94.65994408 58.49052619 91.68581884 62.60491008 94.61219729 57.83089447 90.17785905 74.48615129 93.4965516 67.35493262 90.26509075 72.71082346 93.6796574 67.02249992 90.65168707 71.39541951 93.63903973 66.2732481 91.04027027 71.22225341 93.73955499 65.76120076 91.05312322 69.65454687 93.8135574 65.41911089 91.01377644 68.36620065 93.77271043 64.87770278 91.25005352 67.67890203 93.89777215 64.50846478 93.74920706 47.00811439 95.68704404 46.30596571 93.84416715 47.16545977 95.69710367 46.18271114 93.75034726 46.80400553 95.72296786 46.2103981 93.78314876 46.64050042 95.54650433 45.25139087 93.76522414 46.21345306 95.50444649 44.86478531 93.58149034 45.51768132 95.41938261 44.42558348

Example 3 (According to the Invention)

Shell Catalyst F

(12) 0.77 g of a 3.12% Pd(NH.sub.3).sub.4(OH).sub.2 solution (diluted with 100 ml water) was coated onto 120 g CTR 4*4 mm support tablets (Al.sub.2O.sub.3, BET 3.8 m.sub.2/g) (standard conditions: 70° C. coating temperature, 2×1 tube, 80% spraying rate in the Innojet AirCoater 025), followed by coating-on of 0.40 g of a 7.54% KAuO.sub.2 solution (diluted with 100 ml water) without prior calcining, then drying in the fluidized bed at 90° C. for 45 min, then reduction with forming gas in the gas phase at 150° C. for 3 h.

Example 4 (According to the Invention)

Shell Catalyst G

(13) 0.77 g of a 3.12% Pd(NH.sub.3).sub.4(OH).sub.2 solution (diluted with 100 ml water) was coated onto 120 g CTR 4*4 mm support tablets (Al.sub.2O.sub.3, BET 3.8 m.sub.2/g) (standard conditions: 70° C. coating temperature, 2×1 tube, 80% spraying rate in the Innojet AirCoater 025), followed by coating-on of 5.08 g of a 1.30% Ag(OAc) solution (diluted with 100 ml water) without prior calcining, then drying in the fluidized bed at 90° C. for 45 min, then reduction with forming gas in the gas phase at 150° C. for 3 h.

Example 5 (According to the Invention)

Shell Catalyst H

(14) 0.77 g of a 3.12% Pd(NH.sub.3).sub.4(OH).sub.2 solution (diluted with 100 ml water) was coated onto 120 g CTR 4*4 mm support tablets (Al.sub.2O.sub.3, BET 3.8 m.sub.2/g) (standard conditions: 70° C. coating temperature, 2×1 tube, 80% spraying rate in the Innojet AirCoater 025), followed by coating-on of 0.36 g of a 10.0% Ag(NO.sub.3) solution (diluted with 100 ml water), then coating-on of 0.08 g of a 7.54% KAuO.sub.2 solution, then drying in the fluidized bed at 90° C. for 45 min, then reduction with forming gas in the gas phase at 150° C. for 3 h.

Example 6 (According to the Invention)

Shell Catalyst I

(15) A catalyst was produced analogously to Example 3, with the difference that the reduction was in the gas phase with forming gas at 100° C. for 3 h.

Example 7 (According to the Invention)

Shell Catalyst J

(16) A catalyst was produced analogously to Example 3, with the difference that the two noble metal solutions were combined and were coated on simultaneously under standard conditions (70° C. coating temperature, 2×1 tube, 80% spraying rate in the Innojet AirCoater 025), followed by drying in the fluidized bed at 90° C. for 45 min, then reduction with forming gas in the gas phase at 150° C. for 3 h.

Comparison Example 5

Shell Catalyst K

(17) A catalyst was produced analogously to Example 3, with the difference that, before the application of the gold compound, an intermediate calcining was carried out for 3 h at 375° C.

Comparison Example 6

Shell Catalyst L

(18) A catalyst was produced analogously to Example 4, with the difference that, before the application of the silver compound, an intermediate calcining was carried out for 3 h at 350° C.

Comparison Example 7

Shell Catalyst M

(19) A catalyst was produced analogously to Example 3, with the difference that, before the treatment with forming gas, calcining was carried out for 3 h at 375° C.

Example 8

Results

(20) The activity, stability and selectivity of the catalysts F-M were tested in the selective hydrogenation of acetylene. For this, a mixture of ethylene and acetylene was produced based on the conditions of a “front-end” hydrogenation of a deethanizer unit of an ethylene plant (GHSV 7000, pressure 500 psig). The tests were carried out analogously to the usual technical conditions: Approximately 25 ml of the catalyst formulation is loaded into a double-walled stainless steel reactor with an internal diameter of 1.25 cm, which is heated via a thermostatically controlled water bath. The lowest starting temperature at which less than 25 ppm acetylene is recorded at the outlet of the reactor is called T1. T1 is the measure of the activity of the catalyst.

(21) Acetylene Conversion:
(ppm acetylene at inlet−ppm acetylene at outlet)/(ppm acetylene at inlet)

(22) If, after reaching this temperature, the reactor temperature is further increased, the hydrogenation of ethylene also results, in addition to the desired hydrogenation of acetylene. The selectivity thus decreases.

(23) Acetylene Selectivity:
(ppm acetylene at inlet−ppm acetylene at outlet−ppm ethane at outlet+ppm acetylene at outlet)/(ppm acetylene at inlet)

(24) If the temperature is further increased, the rate of reaction of the hydrogenation of acetylene and ethylene increases further. As the reaction is exothermic, reaction heat is also increasingly released. From a certain point, T2, a “run-away” reaction finally occurs and selectivity is completely lost. T2 is defined as the point at which a 4% loss of hydrogen occurs. The stability of a catalyst is defined as the difference between T1 and T2, the higher this is, the more stable the catalyst is. The temperature of the reaction is varied in the range of from 30 to 104° C. The results of the tests are summarized in Table 3.

(25) TABLE-US-00003 TABLE 3 T1 T2 ΔT Selectivity Catalyst [° C.] [° C.] [° C.] at T1 [%] F 59 92 31 67 G 54 80 26 66 H 63 103 30 80 I 64 99 35 59 J 61 97 36 76 K 61 71 12 28 L 57 71 14 45 M 63 74 11 42

(26) The catalysts F-J according to the invention show a larger temperature window as well as better selectivity than the catalysts K, L and M, for comparable activities (with a tendency to be slightly higher).