CATALYST FOR THE DEHYDROGENATION OF HYDROCARBONS

Abstract

The present invention relates to a catalyst for the dehydrogenation of hydrocarbons which is based on iron oxide and additionally comprises at least one potassium compound, at least one cerium compound, from 0.7 to 10% by weight of at least one manganese compound, calculated as Mn02, and from 10 to 200 ppm of at least one titanium compound, calculated as TiO2, and also to a process for the production thereof. Furthermore, the present invention relates to a process for the catalytic dehydrogenation of hydrocarbons using the catalyst of the invention.

Claims

1-16. (canceled)

17. A process for catalytic dehydrogenation of a hydrocarbon, wherein a mixture of steam and at least one hydrocarbon having a molar steam/hydrocarbon ratio in the range from 3 to 7.35 is brought into contact with a dehydrogenation catalyst comprising at least one iron compound, at least one potassium compound, at least one cerium compound and from 0.7 to 10% by weight of at least one manganese compound, calculated as MnO.sub.2.

18. The catalytic dehydrogenation process according to claim 1, wherein a mixture of steam and at least one hydrocarbon having a molar steam/hydrocarbon ratio in the range from 4 to 7 is used.

19. The catalytic dehydrogenation process according to claim 1, wherein the hydrocarbon is ethylbenzene.

20. The catalytic dehydrogenation process according to claim 1, wherein the dehydrogenation catalyst comprises at least one iron compound, at least one potassium compound, at least one cerium compound, from 0.7 to 10% by weight of at least one manganese compound, calculated as MnO.sub.2, and from 10 to 200 ppm of at least one titanium compound, calculated as TiO.sub.2.

21. The catalytic dehydrogenation process according to claim 1, wherein the dehydrogenation catalyst comprises from 0.7 to 3% by weight of at least one manganese compound, calculated as MnO.sub.2.

22. The catalytic dehydrogenation process according to claim 1, wherein the dehydrogenation catalyst comprises from 30 to 150 ppm of at least one titanium compound, calculated as TiO.sub.2.

23. The catalytic dehydrogenation process according to claim 1, wherein the dehydrogenation catalyst comprises from 50 to 90% by weight of at least one iron compound, calculated as Fe.sub.2O.sub.3; from 1 to 30% by weight of at least one potassium compound, calculated as K.sub.2O; from 0.7 to 10% by weight of at least one manganese compound, calculated as MnO.sub.2; from 10 to 200 ppm of at least one titanium compound, calculated as TiO.sub.2; from 2 to 20% by weight of at least one cerium compound, calculated as CeO.sub.2; and optionally from 0 to 30% by weight of at least one further component.

24. The catalytic dehydrogenation process according to claim 1, wherein the dehydrogenation catalyst comprises from 0.1 to 10% by weight of at least one compound selected from the group consisting of molybdenum, tungsten and vanadium, calculated as oxide in the respective highest oxidation state, as further component.

25. The catalytic dehydrogenation process according to claim 1, wherein the dehydrogenation catalyst comprises from 0.1 to 10% by weight of at least one alkaline earth metal compound, calculated as oxide, as further component.

26. The catalytic dehydrogenation process according to claim 1, wherein the dehydrogenation catalyst comprises from 50 to 90% by weight of at least one iron compound, calculated as Fe.sub.2O.sub.3; from 1 to 30% by weight of at least one potassium compound, calculated as K.sub.2O; from 0.7 to 10% by weight of at least one manganese compound, calculated as MnO.sub.2; from 10 to 200 ppm of at least one titanium compound, calculated as TiO.sub.2; from 2 to 20% by weight of at least one cerium compound, calculated as CeO.sub.2; from 0.1 to 10% by weight of at least one magnesium compound, calculated as MgO; from 0.1 to 10% by weight of at least one calcium compound, calculated as CaO; from 0.1 to 10% by weight of at least one molybdenum compound, calculated as MoO.sub.3; from 0 to 10% by weight of at least one vanadium compound, calculated as V.sub.2O.sub.5, and from 0 to 10% by weight of at least one further component.

Description

[0179] The figures are explained below:

[0180] FIG. 1 shows the styrene yield Y in mol % in the catalytic dehydrogenation of ethylbenzene (as per example 7) at a steam/ethylbenzene weight ratio of 1, a temperature of 620 C. and a space velocity of 1.26 ml of ethylbenzene/[(ml of catalyst).Math.(h)] as a function of the manganese content in % by weight as MnO.sub.2 in the catalyst used (based on the total catalyst), at a titanium content in the catalyst of 70 ppm.

[0181] FIG. 2 shows the styrene yield Y in mol % in the catalytic dehydrogenation of ethylbenzene (as per example 7) at a steam/ethylbenzene weight ratio of 1, a temperature of 620 C. and a space velocity of 1.26 ml of ethylbenzene/[(ml of catalyst).Math.(h)] as a function of the titanium content in ppm in the catalyst used (based on the total catalyst), at a manganese content in the catalyst of 1.8% by weight.

[0182] FIG. 3 shows the styrene yield Y in mol % in the catalytic dehydrogenation of ethylbenzene (as per example 7) at a steam/ethylbenzene weight ratio of 1, a temperature of 620 C. and a space velocity of 1.26 ml of ethylbenzene/[(ml of catalyst)(h)] as a function of the titanium content in ppm in the catalyst used (based on the total catalyst), at a manganese content in the catalyst of 0.02% by weight.

[0183] The styrene yield in mol % is in each case reported as the molar amount of styrene produced based on the molar amount of ethylbenzene used.

[0184] The present invention is illustrated by the following examples.

EXAMPLES

Example 1 (Comparative Example) Catalyst A (without Addition of MnO.SUB.2 .and TiO.SUB.2.)

[0185] An iron oxide Fl (alpha-Fe.sub.2O.sub.3, hematite) comprising 0.027% by weight of manganese (Mn), calculated as MnO.sub.2, and 28 ppm of titanium (Ti), calculated as TiO.sub.2, was used. The BET surface area of the iron oxide Fl was 11 m.sup.2/g.

[0186] Further components used were potassium carbonate, cerium carbonate, magnesium oxide, calcium hydroxide and ammonium heptamolybdate. The compositions of the raw materials used determined by means of elemental analysis are shown below, where the figures relate to the respective element or the respective compound based on the respective total raw material. [0187] Iron oxide F1: 98.9% by weight of Fe.sub.2O.sub.3; <10 ppm of chlorine (Cl); 0.40% by weight of sulfur (S); 170 ppm of manganese (Mn); 17 ppm of titanium (Ti); 0.07% by weight of chromium (Cr); 0.02% by weight of calcium (Ca). [0188] Cerium carbonate: 52.80% by weight of CeO.sub.2; 195 ppm of lanthanum (La); 370 ppm of praseodymium (Pr); 17 ppm of neodymium (Nd); <10 ppm of titanium (Ti); 3 ppm of chlorine (Cl); 10 ppm of calcium (Ca); 0.52% by weight of nitrate. [0189] Magnesium oxide: 93.87% by weight of MgO; 1.40% by weight of calcium (Ca); 0.50% by weight of silicon (Si); 0.35% by weight of iron (Fe). [0190] Calcium hydroxide: 72.65% by weight of CaO; 0.35% by weight of magnesium (Mg). [0191] Ammonium heptamolybdate: 82% by weight of MoO.sub.3; 90 ppm of potassium (K); 50 ppm of sodium (Na).

[0192] A catalyst A having the nominal oxide composition 72.7% by weight of Fe.sub.2O.sub.3, 13.6% by weight of K.sub.2O, 7.4% by weight of CeO.sub.2, 2.2% by weight of MgO, 2% by weight of CaO and 2.1% by weight of MoO.sub.3, 0.02% by weight of Mn0.sub.2 and 20 ppm of TiO.sub.2 was produced.

[0193] For this purpose, the abovementioned pulverulent components were firstly mixed dry and then kneaded with addition of water and starch solution. The catalyst composition was extruded to give pellets having a diameter of 3 mm and dried at 120 C. for 1 hour. The shaped catalyst bodies (pellets) were subsequently calcined in air at 350 C. for 1 hour and 825 C. for 1 hour.

Example 2 (Comparative Example) Catalyst B (without Addition of MnO.SUB.2., with Addition of TiO.SUB.2.)

[0194] A catalyst was produced as described in example 1, but, in contrast to example 1, titanium dioxide (TiO.sub.2) was additionally added. The iron oxide F1 was used.

[0195] A catalyst B having the nominal oxide composition of 72.7% by weight of Fe.sub.2O.sub.3, 13.6% by weight of K.sub.2O, 7.4% by weight of CeO.sub.2, 2.2% by weight of MgO, 2% by weight of CaO, 2.1% by weight of MoO.sub.3, 0.02% by weight of MnO.sub.2 and 70 ppm (mg/kg) of TiO.sub.2 was obtained.

Example 3 (Comparative Example) Catalyst C (Iron Oxide with a Proportion of Ti)

[0196] A catalyst C was produced without addition of MnO.sub.2 and TiO.sub.2 and using an iron oxide F.sub.2 (Fe.sub.2O.sub.3, hematite) comprising 0.025% by weight of manganese (Mn), calculated as MnO.sub.2, and a proportion of titanium of 195 ppm (mg/kg) (corresponds to 325 ppm of Ti, calculated as TiO.sub.2). The BET surface area of the iron oxide F2 was 2.3 m.sup.2/g.

[0197] The composition of the iron oxide F2 was determined by means of elemental analysis and is shown below, where the figures relate to the respective element or compound based on the total raw material. [0198] Iron oxide F2: 99.4% by weight of Fe.sub.2O.sub.3; <10 ppm of chlorine (Cl); 0.16% by weight of sulfur (S); 160 ppm of manganese (Mn); 195 ppm of titanium (Ti); 0.0:2% by weight of chromium (Cr).

[0199] The production of the catalyst was carried out as described in example 1 using further raw materials described in example 1.

[0200] A catalyst C having the nominal oxide composition 72.7% by weight of Fe.sub.2O.sub.3, 13.6% by weight of K.sub.2O, 7.4% by weight of CeO.sub.2, 2.2% by weight of MgO, 2% by weight of CaO, 2.1% by weight of MoO.sub.3, 0.02% by weight of MnO.sub.2 and 240 ppm of TiO.sub.2 was obtained.

[0201] Example 4 Catalysts D-J (different additions of manganese) A series of catalysts D, E, F, G, H, I, J were produced with addition of various amounts of MnO.sub.2. The titanium content was set to a constant 70 ppm in these catalysts. An iron oxide F3 (Fe.sub.2O.sub.3, hematite), comprising 0.27% by weight of Mn (calculated as MnO.sub.2) and traces of Ti (<17 ppm as TiO.sub.2), was used here. The BET surface area of the iron oxide F3 was 1.2 m.sup.2/g.

[0202] Furthermore, potassium carbonate, cerium carbonate, magnesium oxide, calcium hydroxide, ammonium heptamolybdate, manganese dioxide and titanium dioxide were used in such amounts that catalysts having the actual oxide compositions as shown in table 1 were obtained. Unless indicated otherwise, the raw materials described in example 1 were used.

[0203] The compositions of iron oxide F3 and the manganese dioxide used were determined by means of elemental analysis and are shown below, where the figures relate to the respective element or the respective compound based on the respective total raw material. [0204] Iron oxide F3: 99.6% by weight of Fe.sub.2O.sub.3; 280 ppm of chlorine (Cl); <0.01% by weight of sulfur (S); 0.17% by weight of manganese (Mn); <10 ppm of titanium (Ti); <10 ppm of chromium (Cr); <10 ppm of calcium (Ca); 24 ppm of copper (Cu); 50 ppm of sodium (Na); 55 ppm of nickel (Ni); 43 ppm of silicon (Si); 16 ppm of zinc (Zn). [0205] Manganese dioxid: 99.10% by weight of MnO.sub.2; 0.14% by weight of iron (Fe).

[0206] The shaped catalyst bodies were produced as described in example 1.

Example 5: Catalysts K-N (Different Additions of Titanium)

[0207] A series of catalysts K, L, M, N were produced with addition of various amounts of TiO.sub.2. The manganese content was set to a constant 1.8% by weight (calculated as MnO.sub.2) in these catalysts. The iron oxide F3 (Fe.sub.2O.sub.3, hematite), comprising 0.27% by weight of Mn (calculated as MnO.sub.2) and no Ti (<17 ppm calculated as TiO.sub.2), described in example 4 was used here.

[0208] Furthermore, potassium carbonate, cerium carbonate, manganese oxide, calcium hydroxide, ammonium heptamolybdate, manganese dioxide and titanium dioxide were used in such amounts that catalysts having the actual oxide compositions as shown in table 1 were obtained.

[0209] The shaped catalyst bodies were produced as described in example 1. Unless indicated otherwise, the raw materials described in example 1 were used.

Example 6: Catalyst O

[0210] A catalyst 0 was produced with addition of 70 ppm of TiO.sub.2 and using an iron oxide F4 comprising no titanium (<17 ppm as TiO.sub.2) and 0.6% by weight of Mn (calculated as MnO.sub.2). The BET surface area of the iron oxide F4 was 1.1 m.sup.2/g. The production of the catalyst was carried out as described in example 2 with addition of TiO.sub.2 as titanium source. The further raw materials described in example 1 were used.

[0211] The composition of the iron oxide F4 was determined by means of elemental analysis and is shown below, where the figures relate to the respective element or the respective compound based on the total raw material. [0212] Iron oxide F4: 99.4% by weight of Fe.sub.2O.sub.3; 63 ppm of chlorine (Cl); <0.01% by weight of sulfur (S); 0.39% by weight of manganese (Mn); <10 ppm of titanium (Ti); <10 ppm of chromium (Cr); <10 ppm of calcium (Ca); 30 ppm of copper (Cu); 40 ppm of sodium (Na); 100 ppm of nickel (Ni); 36 ppm of silicon (Si); 40 ppm of zinc (Zn).

[0213] Furthermore, potassium carbonate, cerium carbonate, manganese oxide, calcium hydroxide, ammonium heptamolybdate and titanium dioxide were used in such amounts that a catalyst having the nominal oxide composition 72.7% of Fe.sub.2O.sub.3, 13.6% of K.sub.2O, 7.4% of CeO.sub.2, 2.2% of MgO, 2% of CaO, 2.1% of MoO.sub.3, 0.5% by weight of MnO.sub.2 and 70 ppm of TiO.sub.2 was obtained. Unless indicated otherwise, the raw materials from example 1 were used.

[0214] The compositions of the catalysts were checked by means of elemental analysis and are shown in table 1.

TABLE-US-00001 TABLE 1 Compositions of all catalysts (% by weight as oxide). K.sub.2O CeO.sub.2 MgO CaO MoO.sub.3 MnO.sub.2 Fe.sub.2O.sub.3 % by % by % by % by % by % by % by TiO.sub.2 Catalyst weight weight weight weight weight weight weight ppm A 72.7 13.6 7.4 2.2 2 2.1 0.02 20 B 72.7 13.6 7.4 2.2 2 2.1 0.02 70 C 72.7 13.6 7.4 2.2 2 2.1 0.02 240 D 72.5 13.6 7.4 2.2 2 2.1 0.2 70 E 72.2 13.6 7.4 2.2 2 2.1 0.5 70 F 72.0 13.6 7.4 2.2 2 2.1 0.7 70 G 71.5 13.6 7.4 2.2 2 2.1 1.2 70 H 71.2 13.6 7.4 2.2 2 2.1 1.8 70 I 69.5 13.6 7.4 2.2 2 2.1 3.2 70 J 62.5 13.6 7.4 2.2 2 2.1 10.2 70 K 71.2 13.6 7.4 2.2 2 2.1 1.8 0 L 71.2 13.6 7.4 2.2 2 2.1 1.8 30 M 71.2 13.6 7.4 2.2 2 2.1 1.8 150 N 71.2 13.6 7.4 2.2 2 2.1 1.8 200 O 72.2 13.6 7.4 2.2 2 2.1 0.5 70

Example 7: Dehydrogenation of Ethylbenzene to Styrene at an S/HC of 1.0

[0215] The catalysts A to O from examples 1 to 6 were used in the dehydrogenation of ethylbenzene to styrene in the presence of steam. 13.3 ml of catalyst were installed in an isothermal tube reactor. At 620 C. and 1 atm outlet pressure, the catalyst was supplied continuously with 14.6 g/h of ethylbenzene and 14.6 g/h of deionized (DI) water, corresponding to an S/HC weight ratio of 1.0. After stabilization (after about 40 hours), the yield of styrene was determined by gas chromatography. The results in respect of ethylbenzene conversion, styrene selectivity and styrene yield for the various catalysts are shown in table 2 and FIGS. 1 and 2.

[0216] Ethylbenzene conversion, styrene selectivity and styrene yield were determined by means of the following formulae:

Conversion (mol %)=[(A*M.sub.fB*M.sub.p)/(A*M.sub.f)]100

Selectivity (mol %)=[(D*M.sub.pC*M.sub.f)/(A*M.sub.fB*M.sub.p)](M.sub.EB/M.sub.ST)100

Yield (mol %)=conversionselectivity/100

[0217] where: [0218] A: ethylbenzene concentration at the reactor inlet (% by weight) [0219] B: ethylbenzene concentration at the reactor outlet (% by weight) [0220] C: styrene concentration at the reactor inlet (% by weight) [0221] D: styrene concentration at the reactor outlet (% by weight) [0222] M.sub.f: average molar mass of the organic starting materials [0223] M.sub.p: average molar mass of the organic products [0224] M.sub.EB: molar mass of ethylbenzene [0225] M.sub.ST: molar mass of styrene

[0226] The above figures in respect of concentration and molar masses are in each case based on the organic phase (without water).

[0227] FIG. 1 shows the dependence of the styrene yield on the proportion of manganese (Mn) in the dehydrogenation catalyst used. The values relate to catalysts which each have a constant proportion of titanium of 70 ppm (calculated as TiO.sub.2) and to an S/HC weight ratio in the dehydrogenation of 1. It can clearly be seen that an improved yield is obtained at and above a proportion of manganese in the catalyst of at least 0.7% by weight. A particularly high yield of styrene can be achieved using catalysts having a manganese content in the range from 0.7 to 10% by weight, in particular from 0.7 to 5% by weight.

[0228] FIG. 2 shows the dependence of the styrene yield on the proportion of titanium (Ti) in the dehydrogenation catalyst used. The values relate to catalysts which each have a constant proportion of manganese of 1.8% by weight in total (calculated as MnO.sub.2) and to an S/HC weight ratio in the dehydrogenation of 1. It can clearly be seen that an optimized styrene yield is obtained at a titanium content in the range from 10 to 200 ppm, in particular from 30 to 150 ppm, in particular from 50 to 100 ppm.

[0229] FIG. 3 shows the dependence of the styrene yield on the proportion of titanium (Ti) in the dehydrogenation catalyst used. The values relate to catalysts which each have a constant proportion of manganese of 0.02% by weight in total (calculated as MnO.sub.2) and to an S/HC weight ratio in the dehydrogenation of 1. It was able to be shown that only a significantly lower increase in the yield can be achieved by addition of titanium at an S/HC ratio of 1 and in the case of catalysts having a low manganese content. In contrast, the positive influence of the manganese content of at least 0.7% by weight can be improved further by appropriate selection of the titanium content.

TABLE-US-00002 TABLE 2 Results on the dehydrogenation of ethylbenzene at an S/HC weight ratio of 1 and 620 C. Conversion Mn Mn of Yield of addition actual ethylbenzene Selectivity to styrene % % TiO.sub.2 (EB) styrene Mol Catalyst oxide oxide ppm mol % of EB mol % of ST % of ST A 0 0.02 0 62.7 95.9 60.1 B 0 0.02 70 63.8 95.5 60.9 C 0 0.02 240 64.0 96.5 61.8 D 0 0.2 70 63.6 95.9 61.0 E 0.3 0.5 70 64.1 95.9 61.5 F 0.5 0.7 70 65.3 95.9 62.6 G 1.0 1.2 70 70.2 95.2 66.9 H 1.6 1.8 70 68.7 95.2 65.4 I 3 3.2 70 67.8 95.4 64.7 J 10 10.2 70 67.7 95.6 64.7 K 1.6 1.8 0 64.9 95.6 62.1 L 1.6 1.8 30 65.8 95.6 62.9 M 1.6 1.8 150 65.7 95.9 63.0 N 1.6 1.8 200 63.3 96.1 60.9 O 0 0.50 70 62.8 96.2 60.4

Example 8: Dehydrogenation of Ethylbenzene to Styrene at an S/HC of 1.25

[0230] The catalysts A to O from examples 1 to 6 were used in the dehydrogenation of ethylbenzene to styrene in the presence of steam, as described in example 7, with an S/HC weight ratio of 1.25 being set. 13.3 ml of catalyst were installed in an isothermal tube reactor. At 620 C. and 1 atm outlet pressure, the catalyst was supplied continuously with 14.6 g/h of ethylbenzene and 18.25 g/h of deionized (DI) water, corresponding to an S/HC weight ratio of 1.25.

[0231] The results in respect of ethylbenzene conversion, styrene selectivity and styrene yield for the various catalysts are shown in table 3. In addition, table 3 shows the decreases in the styrene yields when changing from an S/HC weight ratio of 1.25 to an S/HC weight ratio of 1.0 (delta Y 1.25.fwdarw.1.0).

TABLE-US-00003 TABLE 3 Results on the dehydrogenation of ethylbenzene at an S/HC weight ratio of 1.25 and 620 C. Conversion Mn Mn of Yield of addition actual ethylbenzene Selectivity styrene Delta Y % % TiO.sub.2 (EB) to styrene mol % of 1.25.fwdarw.1.0 Catalyst oxide oxide ppm mol % of EB mol % of ST ST % A 0 0.02 0 71.4 95.4 68.1 8.0 B 0 0.02 70 70.4 96.1 67.6 6.7 C 0 0.02 240 73.5 95.7 70.3 8.5 D 0 0.2 70 68.5 95.7 65.6 4.6 E 0.3 0.5 70 72.9 95.5 69.6 8.1 F 0.5 0.7 70 71.6 95.6 68.5 5.9 G 1.0 1.2 70 73.1 95.3 69.7 2.8 H 1.6 1.8 70 73.2 95.0 69.5 4.1 I 3 3.2 70 72.7 95.2 69.2 4.5 J 10 10.2 70 72.1 95.6 68.9 4.2 K 1.6 1.8 0 70.0 95.4 66.8 4.7 L 1.6 1.8 30 70.8 95.5 67.6 4.7 M 1.6 1.8 150 72.3 95.6 69.1 6.1 N 1.6 1.8 200 71.7 97.2 69.7 8.8 O 0 0.50 70 71.0 95.9 68.1 7.7

[0232] The improved stability of the catalyst is additionally shown by a smaller loss of catalyst activity when changing from a medium to a low S/HC ratio (comparison of the results of examples 7 and 8).

Example 9: Dehydrogenation of Butene to Butadiene

[0233] The catalyst H was used in the dehydrogenation of 1-butene to butadiene. A volume of 38 ml of catalyst was used in an isothermally heated tube reactor. At 620 C. and 1 atm, the reactor was continuously supplied with 60 g/h of deionized water and 22.5 g/h of 1-butene (corresponding to a molar ratio of steam/butene of 8.6). After stabilization (about 16 hours), the product mixture obtained was analyzed by gas chromatography. The conversion of 1-butene and the butadiene selectivity were calculated using the formulae as in example 7, replacing ethylbenzene by 1-butene and styrene by butadiene. The butene conversion was 23.3 mol % and the butadiene selectivity was 91.2 mol %.