A method of producing a catalyst for low-temperature methanol synthesis

 

(57) Abstract:

The invention relates to the production of catalysts for the process of low-temperature methanol synthesis. The inventive catalyst is produced by termomaslyanym at 250-450C mixed gidroksicarbonata copper-zinc-tungsten-chromium and/or aluminum with structure type hydrozincite-aurichalcite. The catalyst has the composition (mole fraction): si 0,30-0,60; Zn - between 0.30 to 0.62; W - 0,01-0,02; IU+3- 0,08-0,15, O - n, where Me - Al+Cr or Al; n - stoichiometry. The technical result - the development of a new method of producing the oxide catalyst to ensure not only its maximum activity and selectivity, but also maximum stability. 3 table.

Use: petrochemical industry, in particular obtaining catalysts for low-temperature methanol synthesis.

The inventive catalyst is produced by termomaslyanym of gidroksicarbonata copper-zinc-aluminum and/or chromium containing 1-2 at% tungsten, with the structure type hydrozincite-aurichalcite at 250-450oC. the Composition of the catalyst corresponds to the empirical formula

Cu0,30-0,60Znbetween 0.30 to 0.62Wof 0.01-0.02Me0,08-0,15On,

where Me is aluminum and/or chromium, n - stoichiometry of the low temperatures and pressures.

For the process of low-temperature synthesis using oxide copper-zinc-aluminum and copper-zinc-chromium catalysts (synthetic methanol/Ed. by Prof. Karavaeva M. M. - M.: Chemistry, 1984, c. 240; Chemical products on the basis of the synthesis gas.- M.: Chemistry, 1987, c. 248). The conditions of obtaining define the activity, selectivity and stability under the reaction conditions, and hence the service life of the catalysts. Typically, copper-containing catalysts have high activity and selectivity, but low resistance and, therefore, low service life. Furthermore, it is not always reproduce the properties of the catalysts from different parties. This is because in the process of obtaining the formation of several types of oxide copper-containing compounds with different properties.

(EN 2055639 C1, 10.03.96) is proposed to obtain the copper-containing catalyst for methanol synthesis by termomaslyanym soosazhdenie mixed hydrocalumite copper-zinc. The method consists in the following.

Mixed hydroxocobalamine copper-zinc and aluminum and/or chromium produced by co-deposition from a mixture of 10% solutions of metal nitrates 10% solution of ammonium carbonate at a constant pH = 6,9-7,1, constant is the eye of dry air at 250-450oC and tabletirujut with the addition of graphite. The resulting catalyst has a molar ratio of Cu:Zn:Me = 30-55:30-62:8-15, where Me - Al and Cr, or Al, or Cr.

This method produces a catalyst with high activity and selectivity enables the quality control catalyst mass at all stages of preparation of the catalyst, but the stability of the obtained catalyst is not high enough.

The aim of the invention is to develop a new method of producing the oxide catalyst to ensure not only its maximum activity, selectivity and reproducibility of properties, but maximum stability.

The proposed method for the preparation of the catalyst is as follows. Termotasajero at 250-450oC is subjected to mixed gidroksicarbonat copper-zinc-tungsten-aluminum and/or chromium with structure type hydrozincite-aurichalcite composition

Me(OH)6(CO3)2nH2O

where Me=Cu+2, Zn+2, W+6, Al and/or Cr.

To get mixed gidroksicarbonat specified composition and structure is possible by several methods: by coprecipitation, spray drying-calcining a mixture of salt solutions,MINIA and/or chromium. We chose the method of coprecipitation from solutions of salts of copper, zinc, aluminum and/or chromium solution of carbonate or bicarbonate of ammonium, sodium or potassium or mixtures thereof, followed by impregnating the washed precipitate with a solution cremaboldrini heteroalicyclic.

Salts of copper, zinc, aluminum and/or chromium, preferably nitrates, taken in amounts providing the desired ratio of components in the catalyst, dissolved in water and mixed solutions. Solution concentration of 100-200 g/l Separately dissolved in water, the carbonate or bicarbonate of ammonium, sodium or potassium, the concentration of the solution is 100 g/L. Soosazhdenie mixture of solutions of nitrate with a solution of carbonate is carried out in the reactor-the precipitator at a constant pH of 6.0 - 8.0, a constant temperature in the range of 20-85oC and constant stirring. Chemical analysis shows that the selected conditions ensure complete precipitation of metal cations. The precipitate is washed, filtered, impregnated with a solution cremaboldrini heteroalicyclic and dried at a temperature of 80-100oC. the Residue is subjected to x-ray and thermal analysis. In the diffraction pattern of the compound with structure type hydrozincite-aurichalcite has a characteristic set of Maxim the VA mixed hydroxocobalamine d values may have little to deviate from what is shown in the table. A.

On thermograms decomposition of gidroksicarbonata structure hydrozincite-aurichalcite corresponds to the endothermic effect with a maximum at 270-300oC, accompanied by a loss of about 30% of the mass.

The precipitate with the specified structure is heated in a stream of air or inert gas at 250-450oC. the resulting catalyst mass in the form of a powder. The powder catalyst tabletirujut and carry out the measurement of catalytic activity.

The measurement of catalytic activity is conducted in a flow-circulation units at atmospheric pressure and at a pressure of 50 ATM. at 220oC.

The reaction mixture has a composition of CO:CO2:N2:H2= 20:5:5:70. The reaction rate of methanol synthesis at atmospheric pressure for different samples of the catalysts were compared at a constant methanol concentration 110-3vol.%. The volumetric feed rate when tested at a pressure of 50 ATM. - 20000 h-1. thermal stability of the catalysts was characterized by the coefficient of thermal resistance (KTU) is the ratio of the reaction rate after the overheating of the catalyst in the reaction medium at 380oC for 2 h to the initial reaction rate.

The essence of the method is illustrated by the following examples.

Example 1. Termotasajero expose gidroksicarbonat copper-zinc-tungsten-chromium ratio of the components of Cu:Zn:W:Cr=30:60:1:9 (hereinafter, atomic ratio).

To obtain hydroxocobalamine specified composition hold the coprecipitation of a mixture of 10-percentage aqueous solutions of nitrates: 517 ml of nitrate of copper, 1046 ml nitrate zinc, 198 ml of chromium nitrate.

As a precipitator use a 10% solution of ammonium carbonate. For the preparation of solutions and cleaning sludge use distilled or demineralized water.

The deposition is carried out at 70-80oC, pH = 6,9-7,1, with constant stirring. The precipitate is washed, filtered and dried in air at 80-100oC 10-12 hours the Dried sample is impregnated with 120 ml of an aqueous solution cremaboldrini heteroalicyclic (CCP) H4[SiW12O40] containing 2.4 g of the CCP that secures the content of tungsten in the CCP. The sample is dried and analyzed by means of XRD and DTA. It turns out gidroksicarbonat copper-zinc-chromium with structure type hydrozincite-aurichalcite. The results of phase analysis are shown in table. 1. thermal decomposition is carried out at 450oC in irout and placed in a device for the measurement of catalytic activity. The results of the measurement of catalytic activity are shown in table. 2.

Example 2. Termotasajero expose gidroksicarbonat copper-zinc-manganese-chromium ratio of Cu:Zn:W:Al=45:45:1:9.

To obtain hydroxocobalamine specified composition conducting a deposition of a mixture of 10% solutions of salts: 775 ml of nitrate of copper, 784 ml nitrate zinc, 177 ml of aluminium nitrate.

As a precipitator use a 10% solution of ammonium carbonate. The deposition and subsequent operations are performed as in example 1, but the temperature of thermal decomposition - 250oC. the Results of phase analysis and catalytic properties are given in table. 1 and 2.

Example 3. Termotasajero expose hydroxocobalamine copper-zinc-manganese-aluminium ratio of Cu:Zn:W:Cr=60:30:2:8.

To obtain hydroxocobalamine specified composition conducting a deposition of a mixture of 10% solutions of salts: 1033 ml of nitrate of copper, 523, ml nitrate zinc and 176 ml of chromium nitrate.

As a precipitator use a 10% solution of ammonium carbonate. The deposition and subsequent operations are performed as in example 1, but the number of GPC in aqueous solution of 4.8, the Temperature of thermal decomposition - 350oC. the Results of phase analysis and catalytic svojim-aluminum-chromium ratio of Cu:Zn:W:Al:Cr=50:34:1:8:7.

To obtain hydroxocobalamine specified composition conducting a deposition of a mixture of 10% solutions of salts: 861 ml of nitrate of copper, 593 ml nitrate zinc, 157 ml of aluminium nitrate and 153 ml of chromium nitrate.

As a precipitator use a 10% solution of ammonium carbonate. The deposition and subsequent operations are performed as in example 1, but the temperature of thermal decomposition - 350oC. the Results of phase analysis and catalytic properties are given in table. 1 and 2.

As can be seen from the table. 2, the copper-zinc-tungsten-almograve oxide catalysts obtained by the proposed method, are characterized by high catalytic activity and stability.

The proposed method of producing not only provides high activity, selectivity and stability of catalysts, but also gives an opportunity to spend quality control catalyst mass at all stages of preparation of the catalyst, which allows to achieve high reproducibility of properties for different batches of catalysts.

Sources of information

1. Technology of synthetic methanol /Ed. by Prof. Karavaeva M. M. - M. : Chemistry, S. 240, 1984.

2. Chemical products on the basis of the synthesis gas.- M.: Chemistry, S. 248, 1987.

oC mixed hydroxocobalamine copper-zinc-aluminum and/or chromium, followed by pelletizing, characterized in that the mixed hydroxocobalamine use gidroksicarbonat copper-zinc-tungsten-aluminum and/or chromium with structure type hydrozincite-aurichalcite, you get a catalyst, the composition of which corresponds to the empirical formula

Cu0,30-0,60Znbetween 0.30 to 0.62Wof 0.01-0.02Me0,08-0,15On,

where IU - aluminum and/or chromium;

n - stoichiometry.

 

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