YTTRIUM-CONTAINING CATALYST FOR HIGH-TEMPERATURE CARBON DIOXIDE HYDRATION, COMBINED HIGH-TEMPERATURE CARBON DIOXIDE HYDRATION, AND REFORMING AND/OR REFORMING, AND A METHOD FOR HIGH-TEMPERATURE CARBON DIOXIDE HYDRATION, COMBINED HIGH-TEMPERATURE CARBON DIOXIDE HYDRATION AND REFORMING AND/OR REFORMING

Abstract

The invention relates to a process for producing a catalyst for the high-temperature processes (i) carbon dioxide hydrogenation, (ii) combined high-temperature carbon dioxide hydrogenation and reforming and/or (iii) reforming of hydrocarbon-comprising compounds and/or carbon dioxide and the use of the catalyst of the invention in the reforming and/or hydrogenation of hydrocarbons, preferably methane, and/or of carbon dioxide. To produce the catalyst, an aluminum source, which preferably comprises a water-soluble precursor source, is brought into contact with an yttrium-comprising metal salt solution, dried and calcined. The metal salt solution comprises, in addition to the yttrium species, at least one element from the group consisting of cobalt, copper, nickel, iron and zinc.

Claims

1. A catalyst precursor, comprising at least one crystalline material which comprises yttrium and aluminum and has the characteristic that it has a cubic garnet structure, where the catalyst precursor comprises Cu, Zn, Fe, Co and/or Ni and where part of the yttrium and/or aluminum species in the crystalline material is replaced by at least one element selected from the group consisting of Cu, Zn, Ni, Co, and Fe, where a proportion of secondary phases is in the range from 0-49% by weight.

2. The catalyst precursor according to claim 1, wherein the yttrium content is in the range 15-80 mol % and the aluminum content is in the range 10-90 mol %, where the total content of elements selected from the group consisting of Cu, Zn, Ni, Co, Fe is in the range of 0.01-10 mol %.

3. The catalyst precursor according to claim 1, wherein the catalyst precursor comprises, in addition to a main phase cubic garnet structure, at least one secondary phase present in a proportion in the range of 1-49% by weight.

4. The catalyst precursor according to claim 1, wherein the catalyst precursor has a BET surface area which is greater than 2 m2/g.

5. The catalyst precursor according to claim 1, comprising cubic yttrium aluminum garnet as a main phase.

6. The catalyst precursor according to claim 1, further comprising at least one noble metal-comprising promoter selected from the group consisting of Pt, Rh, Ru, Pd, Ir, and Au, where the content of the at least one noble metal-comprising promoter is in the range from 0.001 to 5% by weight.

7. The catalyst precursor according to claim 1, further comprising at least one cationic species element selected from the group I consisting of Ce, La, Pr, Tb, Nd, and Eu, or the group II consisting of Mg, Ca, Sr, Ba, Ga, Be, Cr, and Mn.

8. The catalyst precursor according to claim 1, comprising nickel, wherein part of the yttrium and/or aluminum in the crystalline material is replaced by nickel.

9. A process for producing the catalyst precursor according to claim 1, comprising: (i) contacting an aluminum source with an yttrium-comprising compound and at least one further metal salt of an element selected from the group consisting of copper, zinc, nickel, cobalt and iron, (ii) intimate mixing of the aluminum source which is in contact with the yttrium-comprising compound from, (iii) drying of the mixture, (iv) low-temperature calcination of the mixture, (v) forming or shaping, and (vi) high-temperature calcination of the mixture.

10. The process according to claim 9, wherein the aluminum source comprises one or more basic solutions or dispersions comprising polyaluminum chloride and/or a nanoparticulate aluminum-comprising starting material.

11. The process according to claim 9, wherein the metal salt is present in the form of a melt during the mixing in (ii).

12. A process for carbon dioxide hydrogenation and/or reforming of hydrocarbons, comprising: (a.1) contacting of a feed gas which, if carbon dioxide hydrogenation takes place, comprises hydrogen and carbon dioxide and, if reforming takes place, comprises hydrocarbons and carbon dioxide with the catalyst precursor of claim 1, (a.2) contacting of feed gas with the catalyst present in the reactor occurs at a temperature of 600 C., (a.3) maintaining a process pressure in the reactor of 1 bar during contacting and while the process is carried out, and (a.4) exposure of the catalyst to a gas stream whose GHSV is in the range from 500 to 100 000 hr.sup.1.

13. The process according to claim 12, wherein methane and carbon dioxide are present in the reforming gas stream, with the ratio of methane to carbon dioxide being in the range from 4:1 to 1:2.

Description

EXAMPLES

Example 1

[0158] Synthesis of Fe, Co, Ni or Cu-modified YAGs having the general composition Y.sub.2.68Me.sub.0.32Al.sub.5O.sub.12 (MeFe, Co, Ni or Cu) via the Gilufloc route for 30 g of oxidic product in each case

[0159] Sample 1: Y.sub.2 68Fe.sub.0.32Al.sub.5O.sub.12

[0160] 55.976 g of Gilufloc 83 (from Giulini; Al content 12.4% by weight) were weighed into a 600 ml glass beaker and stirred at room temperature on a magnetic stirrer (50 mm stirrer bar, 150 rpm). 53.306 g of yttrium(III) nitrate hexahydrate (from Alfa Aesar, purity 99.9%) and 6.679 g of iron(III) nitrate nonahydrate (from Sigma Aldrich, purity 99.6%) were weighed into a separate glass beaker and dissolved while stirring (magnetic stirrer, 50 mm stirrer bar, 150 rpm) in as little DI water (conductivity after ion exchange 0.5 micro Siemens) as necessary (about 100 ml). After dissolution, the mixture was quantitatively introduced into the Gilufloc 83 while stirring. The glass beaker was rinsed with DI water.

[0161] The mixture was covered and stirred at 80 C. (50 mm stirrer bar, 150 rpm) for 2 hours. The mixture was then transferred into flat evaporating dishes (Haldenwanger 888-6a/160 mm diameter).

[0162] The filled dishes were placed in a suitable chamber furnace (Nabertherm TH 120/12) and the nitrate decomposition was carried out in a first calcination under synthetic air (CDA) (6 l/min). All hold points were approached at 1K/min and held for one hour (hold points 80 C., 150 C., 200 C., 250 C., 300 C., 350 C. and 450 C.). After the end of the last hold time, the samples were cooled to room temperature (natural cooling of the furnace).

[0163] The oxidic intermediate was then removed from the evaporating dishes and brought to the final particle size (315-500 m). For this purpose, the sample was firstly pressed by means of an agate pestel through a 1000 pm analytical sieve and subsequently through a 500 m analytical sieve (from Retsch). The fines were then separated off by manual sieving (about 10 seconds) by means of a 315 m analytical sieve from the target fraction. The fines were retained as reserve samples.

[0164] The target fraction is calcined again in order to finish phase formation. For this purpose, the sample was calcined in an AlSint crucible (unglazed Al2O3 crucible from Haldenwanger) in a muffle furnace (M110 from Heraeus) at 900 C. (heating ramp 5K/min) for 4 h under CDA (2 1/min). After cooling of the sample to room temperature, any fines (<315 m) formed were separated off by renewed sieving.

TABLE-US-00001 TABLE 1 Overview of weights used for samples 1-4 Gilufloc No. Composition 83 Y(NO.sub.3).sub.36H.sub.2O Fe(NO.sub.3).sub.39H.sub.2O Co(NO.sub.3).sub.26H.sub.2O Ni(NO.sub.3).sub.26H.sub.2O 1 Y.sub.2.68Fe.sub.0.32Al.sub.5O.sub.12 55.976 g 53.306 g 6.679 g 2 Y.sub.2.68Co.sub.0.32Al.sub.5O.sub.12 56.128 g 53.450 g 4.767 g 3 Y.sub.2.68Ni.sub.0.32Al.sub.5O.sub.12 56.135 g 53.457 g 4.85 g 4 Y.sub.3Co.sub.0.32Al.sub.4.68O.sub.12 50.804 g 57.860 g 4.601 g

TABLE-US-00002 TABLE 3 Test procedure for the screening of catalytically active substances As amount of catalyst, 1 ml was used; the particle size fraction of the material was 300-500 m, the internal diameter of the reactor was 5 mm, the length of the catalytic test zone was 5 cm. The respective phases were supplied with the appropriate gas compositions for defined times. These were: phase I 48 h, phase II 48 h, phase III 24 h, phase IV 24 h, phase V 24 h and phase VI 24 h. Phase I Phase II Phase III T [ C.] 750 T [ C.] 750 T [ C.] 750 p [barg] 10 p [barg] 10 p [barg] 10 GHSV [h1] 30000 GHSV [h1] 30000 GHSV [h1] 30000 H2/CO2/CH4 2/1/0 H2/CO2/CH4 3/1/0 H2/CO2/CH4 2/1/0.5 CH4-IN [vol. %] 0 CH4-IN [vol. %] 0 CH4-IN [vol. %] 13.57 CO2-IN [vol. %] 31.67 CO2-IN [vol. %] 25.75 CO2-IN [vol. %] 27.14 H2-IN [vol. %] 63.33 H2-IN [vol. %] 71.25 H2-IN [vol. %] 54.29 Phase IV Phase V Phase VI T [ C.] 750 T [ C.] 750 T [ C.] 750 p [barg] 10 p [barg] 10 p [barg] 10 GHSV [h1] 30000 GHSV [h1] 30000 GHSV [h1] 30000 H2/CO2/CH4 2/1/1 H2/CO2/CH4 1/1/0.5 H2/CO2/CH4 2/1/0 CH4-IN [vol. %] 23.75 CH4-IN [vol. %] 19 CH4-IN [vol. %] 0 CO2-IN [vol. %] 23.75 CO2-IN [vol. %] 38 CO2-IN [vol. %] 31.67 H2-IN [vol. %] 47.75 H2-IN [vol. %] 38 H2-IN [vol. %] 63.33

TABLE-US-00003 TABLE 3 Hydrogen conversion, carbon dioxide conversion, methane yield and methane conversion data for samples 1-4 compared to the commercial reforming catalyst G1-85 (BASF) in phase I to VI Commercial catalyst G1-85 Sample 1 Sample 2 Sample 3 Sample 4 (BASF) Y.sub.2.68Fe.sub.0.32Al.sub.5O.sub.12 Y.sub.2.68Co.sub.0.32Al.sub.5O.sub.12 Y.sub.2.68Ni.sub.0.32Al.sub.5O.sub.12 Y.sub.3Co.sub.0.32Al.sub.4.68O.sub.12 Phase I Conv. H.sub.2[%] 51.42404 29.04 38.75 52.03 50.51 Conv. CO.sub.2 58.3725 60.81 60.96 58.24 58.12 [%] Yield CH.sub.4 16.83877 0.03 7.69 16.35 16.85 [%] Phase Conv. H.sub.2 [%] 48.70494 22.91 39.82 49.37 48.50 II Conv. CO.sub.2 68.26528 69.58 68.96 67.84 68.03 [%] Yield CH.sub.4 29.36827 0.05 19.19 28.74 29.14 [%] Phase Conv. H.sub.2 [%] 29.24043 29.97 32.54 30.45 30.79 III Conv. CO.sub.2 63.47448 62.31 62.34 63.17 62.98 [%] Conv. CH.sub.4 4.79178 4.08 6.80 4.13 6.57 [%] Phase Conv. H.sub.2 [%] 0 29.83 23.79 16.80 17.20 IV Conv. CO.sub.2 0 62.67 63.93 66.47 66.05 [%] Conv. CH.sub.4 0 1.96 2.07 7.75 6.08 [%] Phase V Conv. H.sub.2 [%] 15.08326 43.80 33.13 14.91 14.56 Conv. CO.sub.2 45.62 47.23 50.08 55.54 54.78 [%] Conv. CH.sub.4 0 1.51 7.67 23.91 21.12 [%] Phase Conv. H.sub.2 [%] 0 32.20 46.20 52.46 50.86 VI Conv. CO.sub.2 0 61.25 59.65 58.23 58.31 [%] Yield CH.sub.4 0 0.03 10.95 16.17 16.93 [%]

TABLE-US-00004 TABLE 4 Carbon content in the active compositions after the screening of catalytically active substances Carbon content in % by weight Sample based on the catalyst used G1-85 79.4 Y.sub.2.68Fe.sub.0.32Al.sub.5O.sub.12 1.8 Y.sub.2.68Co.sub.0.32Al.sub.5O.sub.12 <0.1 Y.sub.2.68Ni.sub.0.32Al.sub.5O.sub.12 <0.1 Y.sub.3Co.sub.0.32Al.sub.4.68O.sub.12 <0.1

Example 2

[0165] Sample 5 was produced in a manner analogous to example 1. The X-ray diffraction analysis of the sample indicated a phase-pure garnet material.

TABLE-US-00005 TABLE 5 Overview of the weights used for Sample 5. Gilufloc No. Composition 83 Y(NO.sub.3).sub.36H.sub.2O Fe(NO.sub.3).sub.39H.sub.2O Co(NO.sub.3).sub.26H.sub.2O Ni(NO.sub.3).sub.26H.sub.2O Cu(NO.sub.3).sub.22.5H.sub.2O 5 Y.sub.2.68Cu.sub.0.32Al.sub.5O.sub.12 55.986 g 53.314 g 3.876 g

[0166] The size of the crushed material to be tested was 0.5-1 m; the total catalyst volume in the reactor was 10 ml, the length of the catalytic zone was 8.85 cm, the internal diameter of the reactor was 12 mm. The test program is shown in Table 6; 8 phases were run, and the length of the respective test phases I to VIII was in each case 24 hours per phase. At the end of phase VIII, the catalyst was removed from the reactor and the carbon content on the catalyst was determined.

TABLE-US-00006 TABLE 6 Test procedure for the screening of catalytically active substances. The reaction conditions are indicated for the respective phase. Phase T [ C.] H.sub.2:CO.sub.2:CH.sub.4:H.sub.2O P [barg] GHSV [h.sup.1] I 750 3,0:1,0:0:0 20 30000 II 850 3,0:1,0:0:0 20 30000 III 950 3,0:1,0:0:0 20 30000 IV 950 3,0:1,0:0:0 20 40000 V 950 2,0:1,0:0:0 20 40000 VI 950 2,64:1,0:0,42:0,85 20 40000 VII 950 3.0:1,0:0,3:0 20 40000 VIII 950 3,0:1,0:0:0 20 40000 KEY: decimal commas = decimal points

TABLE-US-00007 TABLE 7 Hydrogen conversion, carbon dioxide conversion, methane yield and methane conversion data for Sample 5 Y.sub.2.68Cu.sub.0.32Al.sub.5O.sub.12 in phase I to VIII Sample 5 Y.sub.2.68Cu.sub.0.32Al.sub.5O.sub.12 Phase I Conv. H.sub.2 [%] 28.25 Conv. CO.sub.2 [%] 69.96 Yield CH.sub.4 [%] 0.37 Phase II Conv. H.sub.2 [%] 29.91 Conv. CO.sub.2 [%] 75.37 Yield CH.sub.4 [%] 1.00 Phase III Conv. H.sub.2 [%] 28.82 Conv. CO.sub.2 [%] 74.90 Yield. CH.sub.4 [%] 1.72 Phase IV Conv. H.sub.2 [%] 31.65 Conv. CO.sub.2 [%] 78.56 Yield. CH.sub.4 [%] 2.91 Phase V Conv. H.sub.2 [%] 32.54 Conv. CO.sub.2 [%] 78.27 Yield. CH.sub.4 [%] 2.47 Phase VI Conv. H.sub.2 [%] 25.20 Conv. CO.sub.2 [%] 65.11 Conv. CH.sub.4 [%] 20.10 Phase VII Conv. H.sub.2 [%] 33.25 Conv. CO.sub.2 [%] 78.88 Conv. CH.sub.4 [%] 10.27 Phase VIII Conv. H.sub.2 [%] 36.86 Conv. CO.sub.2 [%] 78.34 Yield CH.sub.4 [%] 2.06

TABLE-US-00008 TABLE 8 Carbon content in the active compositions after the screening of catalytically active substances Carbon content in % by weight Sample 5 based on the catalyst used Y.sub.2.68Cu.sub.0.32Al.sub.5O.sub.12 <0.1