The way to obtain olefinic hydrocarbons

 

(57) Abstract:

Usage: petrochemistry. Essence: paraffin hydrocarbons digitalout in the presence of a catalyst composition, wt. %: Cr2O310,0-30,0; ZnO 30,0-45,0; Al2O3- the rest. After dehydrogenation catalyst is directed to the regeneration and recovery, which is carried out at a temperature of 640 - 700oWith, naturally, a few less or a few more atmospheric pressure, the flow rate of gas 40 - 60 h-1and residence time of the catalyst in the reduction zone 1 - 3 minutes effect: increase the efficiency of the process, including the output of the target product. 3 C. p. F.-ly, 1 table.

The present invention relates to the field of production of olefinic hydrocarbons, in particular olefinic hydrocarbon, C2-C20by dehydrogenation of the corresponding paraffin hydrocarbons.

Known methods for producing olefinic hydrocarbons by dehydrogenation at elevated temperatures corresponding paraffin hydrocarbons in the presence of catalytic compositions based on noble metals (U.S. patent N 3531543, 4786625, European patent N 351067), and also on the basis of metal oxides in prisutstvie is Tania's story N 2162082). However, both groups of these compounds have drawbacks. The formulations based on noble metals require special processing at the stage of regeneration with the aim of preserving the activity of noble metals, such as processed chlorine-containing substances with subsequent restoration (U.S. patent N 4438288). Structures on the basis of chromium oxide supported on aluminum oxide, silicon oxide, aluminum oxide - silicon oxide, etc. have insufficient selectivity and activity.

Closest to the proposed is a method for olefin hydrocarbons by dehydrogenation of the corresponding paraffin hydrocarbons in the presence of a catalyst composition, wt. %:

Cr2O3- 6,0-30,0

SnO - 0,1-3,5

Me2O - 0,4-3,0

SiO2- 0,08-3,0

Al2O3- Rest

The dehydrogenation process is carried out at a temperature of from 450 to 800oC, a pressure of from 0.1 to 3 ATM abs. and flow rate from 100 to 1000 h-1. After dehydrogenation catalyst regenerate and then restore formed thereon compounds hexavalent chromium (RF Patent N 2127242, 10.03.99, bull. from # 7). The output of the olefin used in this method is not sufficiently high. In addition, significant zatratnye compounds hexavalent chromium from 2 to 3 wt. % fresh and not less than 0.45-0.6. % of catalyst from the system dehydrogenation. Upon decrease of the concentration of compounds of hexavalent chromium to 0.45 wt. percent or less decrease performance dehydrogenation. After regeneration, before feeding into the reactor, the catalyst pre-restore in a special apparatus. This operation is necessary because otherwise compounds of hexavalent chromium, which is a very strong oxidant, restored by oxidizing fed to the dehydrogenation of hydrocarbons. This will significantly decrease the selectivity. Usually used to restore natural gas or, more rarely, a pair of raw material (this is better because when restoring produce less water, but more expensive).

CH4+ CrO3CO2+ CO + H2O + Cr2O3< / BR>
Recovery of the catalyst in industry spend pairs of methane or n-butane in 1-3 min at a flow rate of 100-300 h-1(IC industry, Tsniiteneftehim, M. , N 2, 1971, 1-3, A. C. N 134693, 1959, BI. N 15, 1963).

After recovery of the catalyst was stripped with nitrogen to remove the products of combustion - carbon dioxide and water, which is the catalytic poison. The problem solved by the present invention is to increase effectivestart by dehydrogenation of the corresponding paraffin hydrocarbons in the presence of a catalyst composition, wt. %:

Cr2O3- 10,0-30,0

ZnO - 30,0-45,0

Al2O3- Rest

After the stage of dehydrogenation catalyst is directed to the regeneration and recovery, which is carried out at a temperature of from 640 to 700oC, atmospheric, somewhat less or somewhat greater atmospheric pressure of 0.95-2.1 ATM abs. ), flow rate of gas from 40 to 60 hours-1and residence time of the catalyst in the reduction zone from 1 to 3 minutes. The inventive process can be applied to any dehydrogenation in a fixed, fluidized or moving bed of the catalyst.

Preferred are embodiments of the new method:

- dehydration, regeneration and restoration is carried out in a fluidized bed of catalyst;

the dehydrogenation is carried out at temperatures 500-620oC, a pressure of 1-2 ATM abs. and flow rate from 100 to 600 h-1;

- regeneration of the catalyst is carried out in the presence of air or other oxygen-containing gas at a temperature of 630-670oC, atmospheric or slightly greater atmospheric pressure (1-2 ATM abs. ), volumetric gas velocity from 100 to 500 h1and residence time of the catalyst in C what about the catalyst reduces coke formation, contributes to a more complete and rapid oxidation-reduction reactions on the catalyst. This increases the activity and selectivity of the process, thus increasing the yield of olefinic hydrocarbons. The new catalyst contains substantially fewer compounds hexavalent chromium, respectively, in fresh about 0.5 wt. % and operating system dehydrogenation of 0.12-0.2 wt. %. Low levels of compounds hexavalent chromium simplifies and makes more complete mandatory process of recovery of the catalyst after the regeneration. The application of the new method allows recovery at lower volumetric flow rates of methane: 40-60 hour-1. This allows approximately 2 times to reduce the consumption of energy resources: natural gas and nitrogen. For installation with a capacity of 80000 tons/year natural gas consumption will decrease by about 500000 nm3. In addition, the low content of the compound of hexavalent chromium reduces the toxicity of the catalyst and improves the environment.

Process for the catalytic system used in the new method consists in the dispersion of chromium compounds on the carrier consisting of oxides of aluminum and zinc.

Example 1.

The temperature of the dehydrogenation - ~ 590oC

Regeneration temperature is 650oC

The volumetric rate of 200 h-1< / BR>
The pressure in the regenerator is 1.1 ATM abs.

After regeneration the catalyst to feed in the reactor is recovered at a temperature of 660oC for 2 minutes to remove compounds hexavalent chromium content of 0.12 wt. %) formed ECU 50 h-1the pressure reducer to 1.25 ATM. After reconnection of hexavalent chromium in the catalyst is absent. The results are given in the table.

Example 2.

Microspheric lomography the catalyst having a particle diameter of from 5 to 250 μm, produced by the method of spray-drying the suspension obtained from 1440 g of aluminium spinels synthesized as described in example 1, 500 g of chromium trioxide and 4200 ml of water in a bead mill with stirring for 4 hours at a temperature of 30oC. a Sample of the catalyst is subjected to heat treatment consisting of annealing at 720oC for 4 hours in air flow. The resulting product has the following composition, wt. %:

Cr2O3- 20,8

ZnO - 35,1

Al2O3- 44.1kHz

Dehydrogenation of isobutane to isobutylene is carried out on the installation of the fluidized bed of a catalyst consisting of a reactor and a regenerator with a continuous circulation of the catalyst between them. The dehydrogenation process is carried out at the loaded reactor-regenerator 5500 g of catalyst.

The temperature of the dehydrogenation - ~ 590oC

Regeneration temperature - 660oC

The volumetric rate of 400 h-1< / BR>
Pressure is camping at a temperature of 670oC for 1 minute to remove compounds hexavalent chromium content of 0.15 wt. %) formed in the regenerator. To restore the use of natural gas supplied to the reducing agent with a bulk velocity of 60 h-1the pressure in the reducing agent of 0.95 ATM. After reconnection of hexavalent chromium in the catalyst is absent. The results are given in the table.

Example 3.

Microspheric lomography the catalyst having a particle diameter of from 5 to 250 μm, teaches a method of spray-drying the suspension obtained from 1440 g of aluminium spinels synthesized as described in example 1, 820 g of chromium trioxide and 4600 ml of water in a bead mill with stirring for 2 hours at a temperature of 50oC. a Sample of the catalyst is subjected to heat treatment consisting of annealing at 780oC for 3 hours in air flow. The resulting product has the following composition, wt. %:

Cr2O3- 30,1

ZnO - 31,0

Al2O3- 38,9

The resulting catalyst was tested in the process of dehydrogenation of propane.

Dehydrogenation of propane to propylene is carried out on the installation of a fluidized bed of catalyst consisting of reactorthe in the system of the reactor-regenerator 5500 g of catalyst.

The temperature of the dehydrogenation - 620oC

Regeneration temperature - 670oC

The volumetric rate - 600 h-1< / BR>
The pressure in the regenerator - 1.4 bar abs.

After regeneration the catalyst to feed in the reactor is recovered at a temperature of 680oC for 3 minutes to remove compounds hexavalent chromium content of 0.2 wt. %) formed in the regenerator. To restore the use of natural gas supplied to the reducing agent with a bulk velocity of 60 h-1the pressure in the reducing agent 1.5 ATM. After reconnection of hexavalent chromium in the catalyst is absent.

The results are shown in the table.

Example 4.

Microspheric lomography the catalyst having a particle diameter of from 5 to 250 μm, produced by the method of spray-drying the suspension obtained from 1440 g of aluminium spinels synthesized as described in example 1, 204 g of chromium trioxide and 3400 ml of water in a bead mill with stirring for 3 hours at a temperature of 50oC. a Sample of the catalyst is subjected to heat treatment consisting of annealing at 850oC for 2 hours in air flow. The resulting product has the following composition, mA is in the process of dehydrogenation of isobutane.

Dehydrogenation of isobutane to isobutylene is carried out on the installation of the fluidized bed of a catalyst consisting of a reactor and a regenerator with a continuous circulation of the catalyst between them. The dehydrogenation process is carried out at the loaded reactor-regenerator 5500 g of catalyst.

The temperature of the dehydrogenation - 550oC

Regeneration temperature - 640oC

The volumetric rate of 120 h-1< / BR>
The pressure in the regenerator to 1.9 ATM abs.

After regeneration the catalyst to feed in the reactor is recovered at a temperature of 650oC for 1 minute to remove compounds hexavalent chromium content of 0.15 wt. %) formed in the regenerator. To restore the use of natural gas supplied to the reducing agent with a bulk velocity 40 hour-1the pressure in the reducing agent 2.1 ATM. After reconnection of hexavalent chromium in the catalyst is absent. The results are shown in the table.

1. The way to obtain olefinic hydrocarbons by dehydrogenation of the corresponding paraffin hydrocarbons in the presence of alimohammadian catalyst with subsequent regeneration and restoration, characterized in that - the Rest

and recovery is carried out at a temperature of 640 - 700oWith, naturally, a few less or a few more atmospheric, pressure, flow rate of gas 40 - 60 h-1and residence time of the catalyst in the reduction zone 1 - 3 minutes

2. The method according to p. 1, characterized in that the dehydrogenation, regeneration and restoration is carried out in a fluidized bed of a catalyst.

3. The method according to p. 1, characterized in that the dehydrogenation is carried out at a temperature of 500-620oWith the pressure of 1-2 atmospheres absolute and bulk gas velocity 100 - 600 h-1.

4. The method according to p. 1, characterized in that the regeneration of the catalyst is carried out in the presence of air or other oxygen-containing gas at a temperature of 630-670oWith atmospheric or slightly greater atmospheric pressure, volumetric gas velocity of 100 to 500 h-1and residence time of the catalyst in the regeneration zone 10 - 60 minutes

 

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