CS256308B1 - Process for the treatment of chlorinated hydrocarbon-containing polyalkylbenzenes - Google Patents

Abstract

A method for processing polyalkylbenzenes, which are contaminated with chlorinated hydrocarbons from the Friedel-Kraftsov synthesis of ethylbenzene, into a component for motor gasolines, or for the production of C^ — Οθ — aromatics, by a combination of hydrotreating, distillation of light components, water, HCl and HgS, and catalytic reforming in a mixture with heavy petroleum gasoline.

Description

The invention relates to a method for processing polyalkylbenzenes contaminated with chlorinated hydrocarbon derivatives, which are waste products of the production of ethylbenzene by alkylation of benzene with ethylene by a combination of catalytic hydrotreating and catalytic reforming in a mixture with heavy petroleum naphtha.

When ethylbenzene is produced from benzene by alkylation with ethylene by the Friedel-Krafts process in the presence of aluminum chloride, about 5% of higher alkylated benzenes or diphenylethane-type diaromatics are obtained as a waste product. Under the reaction conditions, chlorinated hydrocarbon derivatives are also formed, which make it difficult to use the waste by-product. Therefore, this product is used as a low-value fuel or is mixed with crude oil in a refinery and separated during its distillation, while the valuable alkylbenzenes are included in diesel fuel. The heavy residue from this fraction can also be advantageously used as dielectric liquids.

The invention solves the utilization of the lighter part of polyalkylbenzenes containing chlorinated hydrocarbons, which are left over during the production of ethylbenzene by alkylation of benzene with ethylene in the presence of a Friedel Krafts catalyst, by preparing a distillate boiling at 210 to 260°C with a yield of 40 to 70% of the left over polyalkylbenzenes, containing mainly diethyl-, triethyl- and butylbenzenes, contaminated with 50 to 500 ppm of chlorinated hydrocarbons, and this is fed together with heavy petroleum gasoline in a mass ratio of 1:5 to 100 into a two-stage complete reforming process, in which in the first refining stage it is heated to temperatures between 250 to 400°C in the presence of a hydrorefining catalyst under a hydrogen pressure of 2 to 3.5 MPa, from the product

- 2 256 308 then distillation at a pressure of 0.15 to 1.8 MPa separates light components, water, hydrogen chloride HCl and hydrogen sulfide HgS, the liquid product is further fed into its own three- to four-reactor reforming system, in which it is heated to a temperature between 420 and 530°C in the presence of a reforming catalyst containing platinum or platinum with rhenium on gamma alumina under a hydrogen pressure of 1 to 4 MPa. The distillate containing polyalkylbenzenes has a boiling point between 150 and 250°C and heavy gasoline between 80 and 200°C, preferably 110 to 180°C. The hydrotreating catalyst contains 15 to 25 8' wt. of molybdenum, cobalt and/or nickel sulfides on gamma alumina and the reforming catalyst 0.3 to 0.4 wt. % platinum and optionally rhenia., The volume rates are 2 to 6 h”^ for hydrotreating, 1 to 2.5 h“ ¹ for reforming, with the volume ratio of the circulating gases being between 100 and 1800 in both stages.

Analysis of the process according to the invention shows that part of the waste polyalkylaromatics can be dechlorinated and partly dealkylated and isomerized under catalytic reforming conditions with prior hydrotreating. The HCl formed is removed during product stripping from H^S and light hydrocarbons and does not affect the Pt catalyst. From the reforming conditions, it is advantageous to work at a higher pressure limit, when dealkylation and isomerization occur faster. The term heavy petroleum gasoline may also refer to gasolines obtained secondarily, e.g. by hydrocracking or other processes.

Example

Distillation of the waste product from the production of ethylbenzene yielded the overhead product, the analysis of which is given in Table 1, with a yield of 50% by weight.

The product was mixed with heavy gasoline to a 10% solution.

Table 2 contains analyses of both raw materials.

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The mixture was introduced onto a Co-Ni-Mo catalyst under the following conditions:

t = 29O°C p = 3.0 MPa LHSV = 3.5 h" ¹ ratio : OH = 250 : 1 vol.

The product was freed from dissolved HgS, small amounts of 0^ - G- hydrocarbons, H ₂ 0 and HC1 by stabilization at a pressure of 0.15 KPa and contained 0.6 ppm Cl and 0.1 ppm S.

The desulfurized products of the hydrotreating were then fed to the reforming stage, where the catalyst with 0.3 wt. % Ft and 0.3 wt. % Re was placed on gamma alumina, in three layers in the ratio

1:2:4.

It was processed under the following conditions:

t = 5O5°C p = 3.5 MPa LHSV =2.0 h ¹ ratio H ₂ : CH = 1000 : 1 vol.

The reaction products are analyzed in Table 3. It is evident that the product from the mixed raw material had a 3-unit higher OČVM, did not contain resins, and the 95% point in the distillation curve increased by 6°G, but the end of distillation dropped significantly. This was also demonstrated by chromatographic analysis, where hydrocarbons above σ^ ₂ completely disappeared, the concentration of benzene and ethylbenzene increased by dealkylation of higher alkylbenzenes. Cg and aromatics with methyl groups formed by isomerization also appeared.

The product was suitable as a high-octane component of motor gasolines or it was possible to obtain increased amounts of Cg - Cg aromatics from it. Depending on temperatures and pressures, product yields varied between 90 and 93 wt. % and OČVM between 86 and 96.

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Table 1

Composition of polyalkylbenzene distillate (PABD)

^day 20 0.880 chromium, analysis % wt. dest. curve C start 86 diethylbenzenes 56.1 10% vol. to 191 butylbenzenes 14.3 50% vol. 201 triethylbenzenes 29.6 95% vol. 231 end 250/98 Table 2 Raw materials for catalytic process heavy gasoline (TB) TB + 10% PABD ^day 20 0 ,749 0.761

dist. curve start °C • 100 102 10% vol. 113 114 50% vol. 133 137 90% vol. 163 179 95% vol. 168 194 end 178 221 sulfur ppm 350 330 chlorine ppm ^1 18

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Table 3

Products of reforming both feedstocks

heavy gasoline TB + 10% PABD product yield % wt. 88.5 90.2 ^day 20 0.775 0.784 start dest. °C 47 37 10% vol. 85 91 50% vol. 123 130 90% vol. 163 178 95% vol. 172 200 end 189 208 OCVM 87.5 90.5 ouch 78.0 80.3 resin mg/100 ml 0.6 0.4 chlorine -cl <L

Claims (3)

A process for the treatment of chlorinated hydrocarbon-containing polyalkylbenzenes, which are produced in the production of ethylbenzene by alkylation of benzene with ethylene in the presence of Friedel-Krafts catalyst, characterized in that a distillate boiling up to 210 to 260 ° C is obtained from 40 70%, containing predominantly diethyl, triethyl and butylbenzenes contaminated by 50 to 500 ppm chlorinated hydrocarbons, and this distillate, together with heavy petroleum gasoline at a weight ratio of 1: 5 to 100, is fed to a two-stage reforming process in which temperatures between 250 and 400 ° C in the presence of a hydrotreating catalyst under a hydrogen pressure of 2 to 3.5 MPa, then the light components, water, HCl and hydrogen sulphide HgS, liquid product are separated from the product by distillation at a pressure of 0.15 to 1.8 MPa is fed further into its own three to four reactor reforming system wherein the catalyst is heated to a temperature between 420-530 ° C in the presence of a reforming catalyst comprising platinum or platinum with rhenium on gamma alumina under a hydrogen pressure of 1 to 4 MPa. 2. Process according to claim 1, characterized in that the polyalkylbenzene-containing distillate has a boiling point between 150 and 250 [deg.] C and a naphtha between 80 and 200 [deg.] C, preferably 110 to 180 [deg.] C. 3. The process according to claim 1, wherein the hydrotreating catalyst comprises 15 to 25 wt. % molybdenum, cobalt and / or nickel sulfides on gamma alumina; and a reforming catalyst 0.3 to 0.4 wt. platinum and possibly. The rhenium and the volumetric velocities are 2 to 6 volumes of feedstock / hydrotreating catalyst volume per hour and 1 to 2.5 h ^-1 on the reforming catalyst, the ratio of circulating gases in both stages being between 100 and 1800 volume.