CZ297807B6 - Catalyst for conversion carbon monooxide with steam and process for preparing thereof - Google Patents

Abstract

The present invention relates to a sulfur resistant catalyst for conversion carbon monooxide with steam containing compounds of cobalt and molybdenum as active components, an alkali metal compound as a promoter, and a carrier. The carrier comprises one or several oxides being selected from the group consisting of TiOi2, Ali2Oi3, and/or MgO, rare earth oxides and/or ZnO, whereby the amount of TiOi2 is in the range of 30 percent by weight to 80 percent by weight, where the percentage is based on the carried total weight. There is also disclosed a process for preparing such catalyst, the process comprises several steps wherein in the first step a) there is mixed an aluminium compound and/or a magnesium compound with one or several compounds being selected from the group consisting of rare earth compounds and zinc compounds functioning as anti-hydration auxiliary compounds, then the resulting mixture is calcined and subsequently the disintegrated solid product is crushed; in the step b) the obtained mixture is mixed in dry state with a titanium compound, subsequently the resulting mixture is extruded to form elongate pieces that are then subjected to calcination in order to obtain a carrier. Subsequently, there is prepared a co-impregnation solution of molybdenum and cobalt compounds as active components of the catalyst and the alkali metal compound. This solution serves for impregnation of the carrier obtained in the step b), and then the impregnated carried is subjected to calcination and disintegration.

Description

Catalyst for the conversion of carbon monoxide by steam and a process for its preparation

Technical field

The present invention relates to a novel sulfur-resistant carbon monoxide conversion catalyst and to a process for the preparation thereof, more particularly to an anti-hydration and sulfur-resistant carbon monoxide rearrangement catalyst and to a process for preparing the catalyst.

BACKGROUND OF THE INVENTION

The conversion of carbon monoxide by steam is known as an important method of producing hydrogen and synthesis gas. A sulfur-resistant catalyst should be used for the starting material having a high sulfur content. Sulfur-resistant catalysts which contain rare earth modified γ-Α1 ₂ 03 or γ-Al ₂ O ₃ as a carrier are currently widely used industrially. Chinese patent CN 1018049 discloses a catalyst comprising γ- _{1 12} Ο ₃ as carrier, Mo and Co as active ingredients and alkali metals as promoters; this catalyst should be propagated at relatively high temperature prior to use. U.S. Pat. No. 4,153,580 discloses that rare earth oxides have been added to the hydrated alumina to be blended, suitably shaped and calcined to obtain a carrier. The carrier obtained was impregnated with a suitable amount of decomposable cobalt and molybdenum compounds which, after impregnation, were converted to oxides to obtain a sulfur-resistant catalyst. Although this catalyst is easy to spread at low temperature, it has little stability to hydration, as does the catalyst disclosed in Chinese patent CN 1018049, which, when used at high water vapor partial pressure, results in some hydration reaction leading to to phase changes and deactivation of the catalyst. To stabilize the structure of these catalysts used at high water vapor partial pressure, a carrier composition of MgO.Al ₂ O ₃ , and TiO ₂ and rare earth compounds as promoters is used, as suggested in Chinese patent CN 1096494, which better solved the problem of hydration . This catalyst is one of the sulfur-free alkali metal catalysts for the conversion of carbon monoxide, since alkali metal compounds are not used in its preparation. Unfortunately, the cost of producing this catalyst is relatively high because grinding and kneading is used. Chinese patent CN 1154271 (application CN 96100935.7) discloses a cost-effective method consisting of dry-blending, kneading, calcination and impregnation. The main carrier components of this catalyst prepared according to this patent are MgO and Al ₂ O 3, with a small amount of TiO ₂ .

The catalyst prepared by this method was sufficiently strong, highly stable and readily regenerable, which may be due to the formation of a spinel structure during the calcination of MgO and Al ₂ O ₃ . The addition of alkali metal compounds in this production improves the efficiency of the catalyst at low temperature, but its hydration resistance, or anti-hydratability, is low.

Nowadays, when designing “coal substitution” for nutrient preparation, large-scale plant fertilizer preparation and re-expansion of medium-sized productions, coal is often chosen as the starting material and three-stage units with a pressure of 4.0 MPa are used. Sulfur resistant process (series connection of medium and low temperature conversion) followed by methanation purification. In the low temperature conversion technology, the catalyst must be operated under difficult conditions of high water vapor partial pressure and at a low temperature, which is typically within no more than 20 ° C of the dew point temperature. That is, the sulfur-resistant conversion catalyst should exhibit not only high activity at low temperature, but also good hydration resistance and structural stability.

-1 CZ 297807 B6

SUMMARY OF THE INVENTION

SUMMARY OF THE INVENTION It is an object of the present invention to provide a catalyst having good anti-hydratability, low temperature activity and structural stability, and is not subject to hydration and phase changes when used under the reaction conditions outlined above.

The sulfur-resistant conversion catalyst of the invention comprises cobalt and molybdenum compounds as active ingredients, an alkali metal compound as a promoter, and a carrier, wherein the carrier comprises one or more oxides selected from the group consisting of T1O2, Al2O3, and / or MgO, rare earth metal oxides and / or ZnO, the T102 content being in the range of 30 wt. % to 80% by weight, wherein these percentages are calculated on the total weight of the carrier.

In preparing the catalyst of the present invention, cobalt and molybdenum compounds are added as an active ingredient, an alkali metal compound as a promoter, an aluminum compound, a magnesium compound, or a combination thereof as a carrier backing material, and one or more compounds selected from the group of rare metal compounds. soils, preferably nitrates thereof, and zinc compounds, preferably zinc oxide and zinc nitrate, as anti-hydrating adjuvants in combination with the titanium compound, wherein the content of the titanium compound in the carrier is preferably controlled in the range of 30 wt. % to 80 wt.%, calculated as TiO ₂ . As a result, the sulfur-resistant water vapor conversion catalyst of carbon monoxide unexpectedly obtains excellent anti-hydratability, good low temperature activity and structural stability.

The content of cobalt and molybdenum compounds as active components of the catalyst containing the active components, the promoter and the carrier is: ΜοΟβ from 5 wt. up to 20 wt. and CoO from 0.5 wt. up to 5% by weight, wherein these percentages are calculated on the total weight of the catalyst comprising the active ingredients, the promoter and the carrier. The content of the alkali metal promoter in the catalyst comprising the active ingredients, the promoter and the carrier is 0.1 wt. % to 20 wt. based on the total weight of the catalyst (calculated as oxides), wherein the alkali metal may be potassium or sodium. For the selection of the percentage range of active ingredients and the alkali metal promoter, see the patents of the People's Republic of China CN 1018049, CN 1042482 and CN 1048989.

The aluminum compounds used as skeletal material in the present invention may be aluminum hydroxide, pseudoboehmite, gybbsit or alumina, preferably aluminum hydroxide or pseudoboehmite. Said magnesium compounds in the present invention may be magnesium hydroxide, magnesium carbonate, magnesium oxide, magnesium nitrate, preferably magnesium carbonate or magnesium oxide. The combination of any two or more of the above compounds can also be used as a scaffold material.

Said zinc compounds may be zinc oxide or thermally decomposable zinc compounds such as zinc nitrate, zinc carbonate and the like, which may decompose into zinc oxide once heated. The anti-hydrating adjuvant used in the present invention may be a lanthanum nitrate or oxide, cerium nitrates or oxides, zinc nitrate and zinc oxide and the like, or a mixture of any two or more of the above compounds, preferably lanthanum nitrate, lanthanum oxide or zinc nitrate .

When the rare earth compounds are used as an anti-hydrating adjuvant, its content should be in the range of 0.01 wt% to 10 wt%. the total weight of the calcined carrier, calculated as oxides.

When the zinc compound is used as an anti-hydrating adjuvant, its content should be in the range of 0.01 wt% to 10 wt%. % of the total weight of the calcined carrier, calculated as oxides.

-2GB 297807 B6

The content of the titanium compound, calculated as titanium dioxide, is preferably in the range of 30 wt. up to 80 wt. the total weight of the calcined carrier.

The titanium compounds used according to the invention may be titanium dioxide, titanium hydroxide 5, metatitanium acid, titanium tetrachloride, rutile or anatase, or a mixture of any two or more thereof, preferably metatitanium acid.

The process for preparing the catalyst support of the present invention is described below. Said aluminum compounds and magnesium compounds are mixed with an anti-hydrating adjuvant selected from the group consisting of rare earth metal compounds, preferably nitrates, and said zinc compounds, in particular zinc oxide and zinc nitrate, after which the resulting mixture is decomposed by calcination and crushes; thereafter the regrind obtained is dry blended with the titanium compound and the resulting mixture extruded and calcined to obtain a catalyst support; by mixing the molybdenum and cobalt compounds as active ingredients and the alkali metal compound, a co-impregnation solution is prepared, and the obtained carrier is saturated with the prepared co-impregnation solution, then the impregnated carrier is calcined and decomposed to the antihydration and sulfur-resistant conversion catalyst of the invention.

When mixing the above mixture with the titanium compound, a peptizer may be added. The peptide may be nitric acid, an aqueous alkaline earth nitrate solution, an aqueous alkali metal nitrate solution, an aqueous alkali metal sulfate solution, or a solution of two or more thereof, especially nitric acid or potassium nitrate solution. The peptizer may also be a solid peptizer, such as alkaline earth metal oxides, alkaline earth metal hydroxides or alkaline earth metal sulfides.

When the catalyst of the invention is used for sulfur-resistant water vapor conversion under severe conditions of 20 ° C below the dew point, there is no hydration or catalyst change, demonstrating high anti-hydratability and structural stability of the catalyst, but using a commercial catalyst for low temperature conversions, eg C25-20-02, QCS-02 and EB30 m4 and the like under the same conditions, all are subject to phase changes (see the attached Fig. 1).

Further, the process for preparing the catalyst of the invention is simple, since grinding and kneading is not performed, which greatly reduces production costs.

The following are illustrations and examples which are illustrative only and do not limit the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Giant. 1 is a diagram of phase changes before and after hydrothermal treatment of the CT-4 catalyst of the invention, wherein the meaning of the symbols is:

and ... prior to hydrothermal working;

b ... after hydrothermal treatment.

Giant. 2 is a diagram of phase changes before and after hydrothermal treatment of several commercial and conventional catalysts, wherein:

and ... fresh commercial catalyst ED-4;

b ... fresh commercial catalyst QCS-02;

c ... fresh commercial catalyst C _{25 2 02} ;

d ... commercial catalyst EB-4 after hydrothermal treatment;

-3EN 297807 B6 e ... commercial catalyst QCS-02 after hydrothermal treatment;

The commercial catalyst C _{25 2 02} after hydrothermal treatment.

Giant. 3 shows the phase spectrum after hydrothermal treatment of a catalyst according to the invention, wherein:

and ... CT-1 after hydrothermal treatment;

b ... CT-2 after hydrothermal treatment;

c ... CT-3 after hydrothermal treatment;

d ... CT-4 after hydrothermal treatment;

DETAILED DESCRIPTION OF THE INVENTION

EXAMPLE 1 Preparation of a Catalyst (1) Preparation of a support

Carrier Z-1

A solution of 10 g of La ₂ O ₃ was prepared, and this solution was mixed with 200 g of Al (OH) ₃ and 100 g of MgCO ₃ . The resulting mixture was calcined at 700 ° C for 2 hours and the calcined product was crushed. To this crushed product was then added 400 g of metatitanium acid, then 10% nitric acid was added and the resulting mixture was kneaded and extruded. The extruded pieces were calcined at 500 ° C. The catalyst support thus obtained was designated as support Z1. Its composition is shown in Table 1.

Carrier Z-2

The preparation was generally the same as the preparation of the Z1 carrier, except that the aqueous solution used contained 30 g of zinc nitrate instead of La ₂ O ₃ . The catalyst support thus obtained was designated as Z-2 Support. Its composition is shown in Table 1.

Carrier Z-3

The preparation was in general steps the same as the preparation carrier Zl, except that there was used 200 g acid metatitaničité instead of 400 g of metatitaničité and that mass use of MgCO ₃ was 0 g instead of 100 g. A catalyst carrier was obtained which was designated as Carrier Z-3. Its composition is shown in Table 1.

Carrier Z-4

The preparation was in the general steps the same as the preparation of the Z-2 support, except that 200 g of metatitanium acid was used instead of 400 g of metatitanium acid. The catalyst support thus obtained was designated as Z-4 support. Its composition is shown in Table 1.

Carrier Z-5

The preparation was the same in general steps as Far Z1, except that 36 g of La ₂ O ₃ was used instead of 10 g of La ₂ O ₃ , the weight of Al (OH) _{3 used} was 0 g instead of 200 g instead of 400 g metatitanium acid. as used from Z1, 200 g of titanium hydroxide was used

And 297 g metatitanium acid. The catalyst support thus obtained was designated as Z-5 support. Its merger is shown in Table 1.

Carrier Z-6

The preparation was generally the same as the preparation of Z-2, except that the weight of zinc nitrate was 90 g, instead of 100 g of MgCl2, 100 g of MgO was used, and the weight of metatitanium acid used was 200 g. thus obtained was designated as Carrier Z-6. Its service is shown in Table 1.

Carrier Z-7

The preparation was generally the same as the preparation of the Z-7 support, except that the weight of the La ₂ O ₃ used was 0.05 g. The catalyst support obtained was designated as the "Z-7 support". Its composition is shown in Table 1.

Carrier Z-8

The preparation was the same as the preparation of the Z-2 support in the general steps except that the weight of the zinc nitrate was 1 g. The catalyst support obtained was designated as the Z-8 support. Its composition is shown in Table 1.

(2) Preparation of the catalyst

First, a co-impregnation solution was prepared from 55 g of ammonium molybdate, 5.0 g of cobalt nitrate and 50 g of potassium carbonate. 50 g aliquots of each test carrier obtained as described above were soaked with this solution. Thereafter, the impregnated supports were calcined and decomposed at 400 ° C to obtain catalysts designated as: CT-1, CT-2, CT-3, CT-4, CT-5, CT-6, CT-7 and CT-1. CT-8, which corresponds to the designation used in the description and table below.

Example 2 Catalyst efficiency test

In a pressurized standard apparatus, filled sequentially with the original catalyst grains, the catalysts of the invention and commercial catalysts, the hydrogen-steam mixture was hydrothermally treated at a temperature of 18 to 20 ° C from the dew point (i.e., pressure: 4.0 MPa, temperature: 220 ° C to 222 ° C, space velocity: 2000 h ^-1 and water / gas ratio: 0.7) for 72 hours, and then changes in the catalyst phase were determined.

The results are shown in Figures 1, 2 and 3. From Figures 1 and 2, it can be seen that the CT-4 catalyst of the present invention was essentially free of any changes after hydrothermal treatment and no hydration peaks occurred. This shows that when the hydrothermal treatment did not form any hydroxide, while any commercial catalysts CN ₂₅ _2 02 QC-02 EB ^ l hydration peaks after hydrothermal treatment emerged (are peaks that we see between 10 and 20) indicating that the catalysts are hydrated. It can be seen from Figure 3 that after hydrothermal treatment, none of the inventive CT-1, CT-2, CT-3 and T-4 catalysts exhibited any hydration and in these cases no hydration peak was formed. Further, the strength of each fresh sample, the cooked sample and the hydrothermally treated sample of the inventive catalyst and commercial catalysts was measured. The data obtained is shown in Table 1, which shows that not all catalysts of the invention have not only better strength than the commercial C25-2-02 catalyst, but also have a higher retention ratio after the boiling test or after the hydrothermal treatment, indicating that the catalysts according to the invention have an extremely high stability.

-5GB 297807 B6

Example 3 Catalyst test in the reaction

The evaluation of the CT-A catalyst according to the invention under simulated conditions was performed under the conditions indicated, including the results of this evaluation in Table 3.

The conditions under which the catalyst was evaluated were as follows: the amount of catalytic charge was 50 ml and the supported catalyst was diluted with α-Al ₂ O ₃ beads to a total volume of 100 ml, with a volume ratio of Al ₂ O ₃ bead / catalyst of 1: 1 .

The catalyst sulfurization conditions were: Pressure: 1.5 MPa, Temperature: 260 ° C, Spatial velocity: 1000 h ^-1 Sulfurization time: 20 h.

Table 1

Carrier C. % TiO ₂ wt. % La ₂ O ₃ wt. % ZnO wt. MgO wt. % Al ₂ O ₃ wt. Z-l 63.3 1.9 9.3 25.4 Z-2 62.9 2.5 9.3 25.3 Z-3 53.4 3.3 43.3 Z-4 45.7 3.6 13.6 37.1 Z-5 78.2 9.4 12.4 Z-6 37.4 9.0 23.2 30.4 Z-7 64.3 0.01 9.6 26.1 Z-8 64.31 0.09 9.6 26.1

Table 2

Catalyst Batch Strength of catalyst according to the invention N / cm commercial catalyst (N / cm) CT-1 CT-2 CT-3 CT ^ 1 C ₂ 5 2-02 Fresh catalyst 126 129 134 136 86 Boiled catalyst Strength 108 116 119 120 64 Retention ratio 85.7 89.9 88.8 88.2 74.4 Hydrothermally treated catalyst Strength 114 112 118 116 67 Retention ratio 90.5 85.7 88.1 85.3 77.9

Table 3

Pressure (MPa) Spatial velocity (h ' ¹ ) Water / gas ratio TvstupfC) CO (% vol) Conversion CO (%) input exit 1.5 1000 1.0 260.6 5.89 0.47 91.58 3.8 3000 0.76 260.0 5.49 0.36 93.11 3.8 2000 0.76 260.1 5.41 0.27 94.75 3.8 2000 0.63 260.0 5.41 0.30 94.16 3.8 2000 0.63 220 5.20 0.34 93.14 3.8 2000 0.63 215 5.29 0.30 94.04 3.8 2000 0.63 210 5.16 0.28 94.31 3.8 2000 0.63 210 3.77 0.20 94.31 3.8 2000 0.63 210 1.67 0.10 94.52 3.8 2000 0.63 205 3.44 0.21 93.69

Claims (18)

PATENT CLAIMS Catalyst for the conversion of carbon monoxide by water vapor resistant to sulfur, comprising cobalt and molybdenum compounds as active ingredient, an alkali metal compound as a promoter, and a carrier, characterized in that the carrier comprises one or more oxides selected from the group consisting of TiO ₂ , Al ₂ O ₃ , and / or MgO, rare earth oxides and / or ZnO, the TiO ₂ content being in the range of 30 wt. % to 80% by weight, wherein these percentages are calculated on the total weight of the carrier. Catalyst according to claim 1, characterized in that the content of cobalt and molybdenum compounds as active components of the catalyst is: MoO ₃ from 5 wt. up to 20 wt. and CoO from 0.5 wt. up to 5% by weight, wherein these percentages are calculated on the total weight of the catalyst comprising the active ingredients, the promoter and the carrier. Catalyst according to claim 1, characterized in that the content of said alkali metal promoter is 0.1% by weight. % to 20 wt. based on the total weight of the catalyst comprising the active ingredients, the promoter and the carrier, the content of the alkali metal compounds is calculated as if they were present in the form of oxides, said alkali metal being potassium or sodium. Catalyst according to one of Claims 1 to 3, characterized in that the content of said rare earth metal oxides is 0.01% by weight. % to 10 wt. the total weight of the carrier. Catalyst according to one of claims 1 to 3, characterized in that said rare earth oxides are selected from the group consisting of lanthanum oxide or cerium oxides. Catalyst according to one of claims 1 to 3, characterized in that said rare earth metal oxides are formed by lanthanum oxide. Catalyst according to claim 6, characterized in that the lanthanum oxide content is 0.01% by weight. % to 10 wt. the total weight of the carrier. Catalyst according to one of Claims 1 to 3, characterized in that the ZnO content is 0.10% by weight. % to 10 wt. the total weight of the carrier. 9. A process for the preparation of a water-resistant carbon monoxide conversion catalyst according to any one of claims 1 to 8, characterized in that the steps of a) mixing the aluminum compound and / or magnesium compound with one or more compounds selected from the group consisting of rare earth metal compounds and zinc compounds as anti-hydration auxiliary compounds, the resulting mixture is calcined and then the decomposed solid product is crushed; b) mixing the obtained mixture in step a) with the titanium compound in the dry state, followed by extruding the resulting mixture into elongated pieces which are subjected to calcination to obtain the catalyst support; and c) preparing a co-impregnating solution of molybdenum and cobalt compounds as catalyst and alkali metal active ingredients, impregnating the support obtained in step b) and calcining and decomposing the impregnated support. 10. The method of claim 9 wherein said aluminum and magnesium compounds are one or more selected from the group consisting of aluminum hydroxide, pseudoboehmite, gybbsit, alumina, magnesium hydroxide, magnesium carbonate, magnesium oxide. -7EN 297807 B6 The method of claim 9, wherein said anti-hydration adjuvant is one or more compounds selected from the group consisting of nitrate or lanthanum oxide and nitrates or oxides of cerium. The method of claim 9, wherein said titanium compound is one or more selected from the group consisting of titanium dioxide, titanium hydroxide, metatitanium acid, titanium tetrachloride. The method of claim 12, wherein the titanium oxide is rutile or anatase. The method of claim 9, wherein the content of said rare earth is 0.01 wt%. up to 10% by weight, of the total weight of the calcined carrier, calculated as oxide. 15. The process of claim 9 wherein the zinc compound content is 0.1 wt%. % to 10 wt. the total weight of the calcined carrier, calculated as the oxide. The method of claim 15, wherein said zinc compound is one or more compounds selected from the group consisting of zinc oxide, and thermally decomposable zinc compounds that are degradable upon heating to zinc oxide. 17. The method of claim 15 wherein said zinc compound is zinc nitrate or zinc oxide. 18. The process of claim 9 wherein said rare earth metal compounds are lanthanum nitrates or oxides.