DE1229990B - Process for producing a Cr-Cu-Zn oxide catalyst - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

BOIj

German KL: 12 g -11/50

Number: 1229 990

File number: P 34664IV a / 12 g

Filing date: July 10, 1964

Opening day: December 8, 1966

; .. The invention relates to a method for producing a Cr-Cu-Zn oxide catalyst. Catalysts of this type are known to be used to promote conversions between gases; At relatively low temperatures, the conversion of CO and steam to CO ₂ and H ₂ and, under pressure, the conversion of CO ₂ and H ₂ and hydrogen to methanol is promoted.

It is known to prepare catalysts containing metal oxides and chromium oxide in such a way that a mixture of the corresponding metal salts, ζ. B. metal formates or acetates, thermally decomposed or soluble salts of metals including d ^: it dissolves chromium in water, from the solution by means of a precipitant, such as ammonia or sodium hydroxide, a mixture of metal hydroxides falls, the precipitate is filtered off, dried and calcined. Apart from the cost of the metal salts required, this process is cumbersome and therefore time consuming. ^ao

- To overcome these disadvantages, the process of the invention is used to produce Cr-Cu-Zn-oxide catalysts for converting CO and steam to CO ₂ and H ₂ in the manner that _: copper and zinc oxide are mixed dry, this Solid ammonium dichromate is added to the mixture or a paste is formed therefrom by adding a concentrated ammonium dichromate solution, whereupon the mixture is heated until the ammonium dichromate decomposes and, if necessary, shaped in a known manner. To decompose the Ammoniumdichromats a dry mixture to about 300 ⁰ C, a pasty mixture is heated to about 350 ⁰ C. The dry ingredients should be mixed carefully and without shaking to avoid premature decomposition of the ammonium dichromate.

The powdery catalyst obtained can be converted into forms suitable for its application purposes, z. B. be tabletted. For this purpose, a mixture of the catalyst and a Lubricants can be used.

The advantageous effect of one according to the invention results from the following comparative tests Catalyst. Four catalysts A, B, C and D were prepared for these comparative experiments the catalysts A and B by the known method from a solution of metal salts Precipitate oxides and catalysts C and D according to the process of the present invention.

Catalyst A: 270 g of zinc nitrate, 30 g of chromium nitrate and 36 g of copper nitrate were dissolved in 2.5 liters of water
Cr-Cu-Zn oxide catalyst

Applicant:

The Power-Gas Corporation Limited,

Stockton-on-Tees, Durham (UK)

Representative:

Dr.-Ing. E. Berkenfeld

and Dipl.-Ing. H. Berkenfeld, patent attorneys,

Cologne-Lindenthal, Universitätsstr. 31

Named as inventor:

Ronald Bennett Oliver,

Linthorpe, Middlesbrough, Yorkshire

(Great Britain)

Claimed priority:

Great Britain 17 July 1963 (28 224)

and 8O ⁰ C with 140 ml of 0.88 ammonia η precipitated at a pH 7.0 übersteigendem not. The precipitate was filtered off, washed and dried at 110 ° C. overnight. The product was then heated to 35O ⁰ C for four hours, cooled, mixed with 2% graphite and tableted mm to tablets of a size of 6.25 ·.

Catalyst B: 270 g of zinc nitrate, 30 g of chromium nitrate and 36 g of copper nitrate were dissolved in 2.5 liters of water and ^{precipitated at 50 °} C. by adding a solution of 150 g of ammonium carbonate in 1 liter of water. The precipitate was filtered off, washed and dried ^{at 110 ° C. overnight.} The product was then heated to 35O ⁰ C hours, cooled and mixed with 2% graphite and pelleted to Tabel mm tablets of a size of x 6.25.

Catalyst C: 80 g of zinc oxide, 13 g of copper oxide and 22 g of ammonium dichromate were ground in a mortar. The mixture obtained was ^{heated to 300 °} C. in an oven, annealed at this temperature, and the vapors developed were discharged. The calcined powder was cooled, _{mixed with 2 ° / 0} graphite and tabletted into tablets of 8 x 6.25 mm.

Catalyst D: 80 g of zinc oxide and 13 g of copper oxide were triturated together. 22 g of ammonium dichromate were dissolved in 30 ml of water ^{at 40 ° C. and}

609 730/387

the solution was added dropwise to the mixture of zinc and copper oxides, and a paste was formed. The paste was ^{heated to 350 °} C. for 1 hour. The pulverized product was cooled, mixed with 2% graphite and formed into tablets of 8 x 6.25 mm. To test the influence of the catalysts on the conversion of CO and water vapor to CO ₂ and H ₂ , the catalyst tablets were placed in a glass tube with a 25.4 mm bore that was electrically heated to the desired temperature. A gas containing 35% CO, 30% H ₂ and 35% N ₂ (vol / vol.) Was mixed with steam in a ratio of 1: 1 (vol / vol.) And over the catalyst tablets at 250 and 300 ° C, respectively and passed at a throughput rate of approximately 4000 ecm gas / ccm catalyst / h. The outlet gas was analyzed for its CO content based on the dry gas. The results are given in the table below.

catalyst

Throughput speed
ecm gas / ccm
Catalyst / h

3900
4000
3900
4100

% CO (VoL / Vol.)
in the dry exit gas

catalyst
at 250 ^° C

no test
22.0
21.2
17.4

catalyst
at 300 ⁰ C

23.0
18.9
18.7
13.5

The lower the CO content of the dry exit gas, the higher the effectiveness of the catalyst. The table shows that the inventive catalysts C and D are more effective than that known catalysts A and B.,

In order to investigate the service life of the catalysts produced according to the method of the invention, tablets produced from the catalyst (6.25 × 6.25 mm) were placed in a ^{glass tube heated electrically to 200 °} C. with a bore of 25.4 mm. A gas and water vapor containing 6.7% CO ₂ , 36.6% CO, 34.0% H ₂ and 22.7% N ₂ (vol / vol. Dry) in a ratio of 1: 1 (vol / vol.) Was used passed over the catalyst tablets at an hourly throughput rate of approximately 3000 ecm gas / ccm catalyst. The outlet gas was examined for its CO content at intervals of several days during continuous operation. The results are shown in the table below.

Test duration
(Days)

Beginning

10 ....

21 ....

32 ....

% CO (VoL / Vol.)

in the dry exit gas

(Catalyst at 200 ° C)

13.9
17.1
16.4
18.2

The results show how the effectiveness of the catalyst gradually decreases with the duration of the experiment. After this experiment the catalyst became

ao regenerated by passing a mixture of air and steam over the catalyst tablets at 300 ^° C. for 2 days.

The efficiency of the regenerated catalyst was then assessed using the same inlet gas

as tested at an hourly flow rate of approximately 3000 cc gas / cc catalyst and at a catalyst temperature of 200 ⁰ C. Analysis indicated that the exit gas contained 13.5% CO (dry), indicating that the regenerated catalyst was initially somewhat more effective than the original catalyst.

Claims (1)

Claim: Process for producing Cr-Cu-Zn-oxide catalysts for converting CO and steam to CO ₂ and H ₂ , characterized in that copper and zinc oxide are mixed dry, solid ammonium dichromate is added to this mixture or a concentrated ammonium dichromate solution is added Paste forms therefrom, whereupon the mixture is heated until the ammonium dichromate decomposes and, if necessary, shaped in a known manner. 609 730/387 11.66 ® Bundesdruckerei Berlin