Catalyst for dehydrogenation of paraffin hydrocarbons

 

(57) Abstract:

The invention relates to catalysts for dehydrogenation of paraffin hydrocarbons. The catalyst contains 10-30 wt.% oxide of chromium, 0.5 to 2.5 wt.% oxide of an alkali metal, mainly potassium, 0.5 to 2.0 wt.% silicon dioxide, 0.1 to 1.5 wt.% of boron oxide and aluminum oxide - rest. The catalyst has a high activity and selectivity at low coxworthy. table 1.

The present invention relates to the production of catalysts for dehydrogenation of paraffin hydrocarbons.

Known catalyst for dehydrogenation of paraffin hydrocarbons containing, wt.%:

Cr2O3- 12,2

K2O - 1,4

SiO2- 2,0

Al2O3- 2,0

(U.S. Pat. RF N 1366200, publ. BI N 2, 15.01.1988).

Closest to the present invention is a catalyst for dehydrogenation of paraffin hydrocarbons, comprising, by wt.%:

Cr2O3- 6,0 - 30,0

SnO - 0,1 - 3,5

Me2O - 0,4 - 0,3

SiO2- 0,08 - 3,0

Al2O3- Rest

where Me is an alkaline metal

(U.S. Pat. RF N 2127242, publ. BI N 7, 10.03.1999).

Both of these catalyst have a high enough active the invention is to improve the efficiency of the catalyst.

Offered the catalyst for dehydrogenation of paraffin hydrocarbons, including the chromium oxide of the alkali metal oxide, silicon oxide, aluminum oxide and, optionally, an oxide of boron in the following content, wt.%:

Cr2O3- 10,0 - 30,0

Me2O - 05 - 2,5

SiO2- 0,5 - 2,0

B2O3- 0,1 - 1,5

Al2O3- Rest

where Me is an alkaline metal

As the alkali metal catalyst preferably contains potassium.

The difference between the new catalyst from the prototype is the exception to the content of tin oxide, the content of boron oxide at the specified content components, and the preferred content of potassium as the alkali metal.

The use of the catalyst of the inventive combination of components in a given volume can reduce the coke formation, promotes more rapid and complete oxidation-reduction reactions. This reduces the proportion of adverse reactions, increasing the activity and selectivity of the operation of the catalyst.

The process of obtaining a new catalytic system consists in the dispersion of the chromium compounds, alkali metal and boron La on the media, consisting of oxides of aluminum, silicon and boron. The following are possible methods of preparation of the catalytic system.

The preparation of the catalyst can be carried out by impregnation of the specified carrier with a solution containing precursors of the oxides of chromium, boron and potassium, with subsequent drying and calcination or ionic absorption with subsequent separation of the liquid, drying and calcination of the solid substance.

Preferably the conducting impregnation method "initial humidity of the carrier with a solution containing all of the precursors of the active components.

As for boron are other techniques by which it can be added to the catalytic system:

- the addition of boron to the media before applying the precursors of the oxides of chromium and potassium

- treatment of solids containing the oxides of chromium and potassium solution containing the boron compounds using ion exchange, impregnation, etc.

- deposition of boron compounds by parasitemia to the media, to Supplement the precursors of the oxides of chromium and potassium, using volatile substances.

- deposition of boron compounds by parasitemia solid substance containing: oxide of aluminum, oxlade the carrier impregnated with the solution, containing the precursors of the active elements: oxides of chromium, potassium and boron, and boron additive to the carrier before applying the precursors of the oxides of chromium and potassium.

As a precursor of boron oxide can be used as inorganic and organic boron compounds.

The invention is illustrated by the following examples.

Example 1

Resulting pseudoboehmite with the addition of silicon oxide (1.5 wt%), having a particle diameter of from 5 to 250 microns, was obtained by spray-drying a suspension of pre-hydrated aluminium oxide, to which the hydration add silicic acid. Sample pseudoboehmite is subjected to heat treatment consisting of heating at a temperature of 150oC for 2 hours and calcination at 800oC for 4 hours in air flow.

The resulting product had a specific surface area of 170 m2/g, a porosity of 0.39 g/cm3and consisted mainly of gamma, Delta and theta transition alumina.

200 g of this alumina was impregnated, using the technique of "initial" moisture, aqueous solution (78 cm3containing of 67.1 g CrO3(and 99.8 wt.%), are 5.36 g of KOH (85%) and 0.5 g (H3BO3(and 99.8 wt.%) in the 1 hour, then dried at a temperature of 90oC for 6 hours. The dried product was activated in a current of air at a temperature of 700oC for 4 hours.

Obtain a catalyst having the following composition, wt.%:

Cr2O3- 20,0

K2O - 1,5

SiO2- 1,2

B2O3- 0,1

Al2O3- Rest

The resulting catalyst was tested in a process for the dehydrogenation of isobutane and propane, performed at a temperature of 560-590oC, space velocity of the raw material 400 l of reagent/l of catalyst per hour in the laboratory quartz reactor. The catalytic cycle that simulates carrying out the reaction in an industrial reactor consists of a reaction phase, in which the hydrocarbons are served within 30 minutes; phase blowdown, when nitrogen is passed for 10 minutes to release the catalyst from the adsorption of the reaction products of dehydrogenation; regeneration phase, when in the regenerator the gas is fed to the regeneration air for 30 minutes (in these experiments) and again the blowdown phase when nitrogen is passed for 10 minutes to release the catalyst from the adsorbed reaction products of regeneration. Specifications industrial dehydrogenation process in p is atory reaction: in this case, regeneration and restoration was carried out at 650oC, whereas the dehydrogenation was carried out at 560-590oC. the results are shown in the table.

Example 2

200 g microspherical alumina, obtained as described in example 1 was impregnated according to the method described here previously, aqueous solution (78 cm3containing of 67.4 g CrO3(and 99.8 wt.%), are 5.36 g of KOH (85%) and 0.9 g H3BO3(and 99.8 wt.%) in deionized water at the same temperature as in example 1. Obtain a catalyst having the following composition, wt.%:

Cr2O3- 20,0

K2O - 0,5

SiO2- 1,2

B2O3- 0,1

Al2O3- Rest

The resulting catalyst was tested in the process of dehydrogenation of isobutane and propane, as described in example 1. The results are shown in the table.

Example 3

200 g microspherical alumina, obtained as described in example 1 was impregnated according to the method described here previously, aqueous solution (78 cm3containing 30,6 g CrO3(and 99.8 wt.%), 8,14 g KOH (85%) and 6.7 g H3BO3(and 99.8 wt.%) in deionized water at the same temperature as in example 1. Obtain a catalyst having the following composition, wt.%:

Cr2O3- 10,0

K2O - 2,5

SiO2- the processes of dehydrogenation of isobutane and propane, as described in example 1. The results are shown in the table.

Example 4

Resulting pseudoboehmite with the addition of silicon oxide (0.6%), having a particle diameter of from 5 to 250 microns, was obtained by spray-drying a suspension of pre-hydrated aluminium oxide, to which the hydration add silicic acid. Sample pseudoboehmite is subjected to heat treatment consisting of heating at a temperature of 150oC for 2 hours and calcination at 800oC for 4 hours in air flow.

The resulting product had a specific surface area of 180 m2/g, porosity of 0.48 g/cm3and consisted mainly of gamma, Delta and theta transition alumina.

200 g of this alumina was impregnated, using the technique of "initial" moisture, aqueous solution (96 cm3containing 113,6 g CrO3(and 99.8 wt.%. ), 6,04 g KOH (85%) and 0.5 g of H3BO3(and 99.8 wt.%) in deionized water at a temperature of 85oC. the Impregnated product was left at room temperature for 1 hour, then dried at a temperature of 90oC for 6 hours. The dried product was activated in a current of air at a temperature of 700oC for 4 hours.

Get Catalin2O3- 0,1

Al2O3- Rest

The resulting catalyst was tested in the process of dehydrogenation of isobutane and propane, as described in example 1. The results are shown in the table.

Example 5

Resulting pseudoboehmite with the addition of silicon oxide (2.5 wt.%), having a particle diameter of from 5 to 250 microns, was obtained by spray-drying a suspension of pre-hydrated aluminium oxide, to which the hydration add silicic acid. Sample pseudoboehmite is subjected to heat treatment consisting of heating at a temperature of 150oC for 2 hours and calcination at 850oC for 4 hours in air flow.

The resulting product had a specific surface area of 160 m2/g, a porosity of 0.40 g/cm3and consisted mainly of gamma, Delta and theta transition alumina.

200 g of this alumina was impregnated, using the technique of "initial" moisture, aqueous solution (80 cm3containing of 67.1 g CrO3(and 99.8 wt.%), are 5.36 g of KOH (85%) and 0.5 g of H3BO3(and 99.8 wt.%) in deionized water at a temperature of 85oC.

The impregnated product was left at room temperature for 1 hour, then dried at temperatureoC for 4 hours.

Obtain a catalyst having the following composition, wt.%:

Cr2O3- 20,0

K2O - 1,5

SiO2- 2,0

B2O3- 0,1

Al2O3- Rest

The resulting catalyst was tested in the process of dehydrogenation of isobutane and propane, as described in example 1. The results are shown in the table.

Example 6

200 g microspherical alumina, obtained as described in example 1 was impregnated according to the method described here previously, aqueous solution (78 cm3containing of 67.4 g CrO3(and 99.8 wt.%), lower than the 5.37 KOH (85%) and 2.46 g H3BO3(and 99.8 wt.%) in deionized water at the same temperature as in example 1.

Obtain a catalyst having the following composition, wt.%:

Cr2O3- 20,0

K2O - 1,5

SiO2- 1,2

B2O3- 0,5

Al2O3- Rest

The resulting catalyst was tested in the process of dehydrogenation of isobutane and propane, as described in example 1. The results are shown in the table.

Catalyst for dehydrogenation of paraffin hydrocarbons, including chromium oxide, alkali metal oxide, silicon oxide, aluminum oxide, characterized in that the 0,0

Me2O - 0,5 - 2,5

SiO2- 0,5 - 2,0

B2O3- 0,1 - 1,5

Al2O3- Rest

where Me2O - alkali metal.

2. The catalyst p. 1, characterized in that it contains as an alkali metal is potassium.

 

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