RU2007378C1 - Method of cyclopentadiene synthesis - Google Patents

Abstract

FIELD: organic chemistry. SUBSTANCE: cyclopentadiene is synthesized by depolymerization of dicyclopentadiene at 150-250 C in the presence of nickel-chrome catalyst activated with hydrogen at 150-200 C and at volume ratio catalyst: hydrogen = 1: (2000-3000) following by treatment with air at volume ratio catalyst: air = 1: (0,11-0,21). Synthesized compound is used for ethylene-propylene rubbers production. EFFECT: improved method of synthesis.

Description

 The invention relates to the field of petrochemistry, and in particular to a method for producing cyclopentadiene (CPP), which is a comonomer in the production of rocket and jet fuels, for the production of hardeners, etc.

A known method of producing cyclopentadiene by gas-phase thermal decomposition of dicyclopentadiene (DCPD). Dicyclopentadiene previously vaporized at 170-175 ^{° C} in the thermal splitting cube reactor, and then in the tubular part of the reactor is carried decomposition of dicyclopentadiene at 280-380 ^{° C} followed by quenching the resulting cyclopentadiene. The disadvantage of this method is the high temperature in the tubular part of the reactor (280-380 ^about C), in addition, the residence time of dicyclopentadiene in the cube of the reactor can reach 2 hours, which at the temperature of the cube leads to the formation of by-products.

Another known method for producing cyclopentadienes, wherein Dedicated _C5-fraction of liquid pyrolysis product is subjected to catalytic monomerization at 300-400 ^C, space velocity 1.5 h ^-1, the atmospheric pressure on a catalyst containing silicon dioxide, aluminum oxide, calcium oxide, potassium oxide, magnesium oxide. The disadvantage of this method is the use of high temperature.

Closest to the claimed technical solution is a method for producing cyclopentadiene by monomerization of dicyclopentadiene over active γ-alumina. Cyclopentadiene dimer is passed through a fixed catalyst bed at a temperature of ^about 200-450 C. and the volumetric feed rate 1,0-7,5 ^h-1 at atmospheric pressure. This method has two significant disadvantages:
Maximum yield CPD (91.5%) and the highest conversion (97.7%) were obtained at the process temperature ^of 300-400 C and more atmospheric distillation catalyzate obtained;
the formation of reaction by-products in the catalysis, which requires the separation of pure CPD by atmospheric distillation.

 The purpose of the proposed technological solution is to increase the yield and purity of cyclopentadiene.

This goal is achieved by the use of a pre-activated industrial nickel-chromium catalyst in the process of dicyclopentadiene monomerization. Catalyst activation is carried out by passing hydrogen through its layer at a volume ratio of catalyst: hydrogen = 1: 2000-3000, at a temperature of 150-250 ^C. The catalyst was then treated with air in a volume ratio of catalyst: air = 1: 0,11-0, 21.

The use of this catalyst allows to reduce the temperature monomerization dicyclopentadiene process to 150-250 ^{° C} and significantly reduce power consumption while increasing output of cyclopentadiene in comparison with the prototype.

Nickel-chromium catalyst is an industrial hydrogenation catalyst and has the following composition, wt. %:
Ni (in terms of dry matter) 48-51
Cr oxide content
in terms of dry matter 26-29 Iron content <0.5
Sulfide sulfur content <0.5 (I grade), 0.1 (II grade) Moisture content <3 (I grade),
5 (II grade) Graphite content 5
Alumina Content Else
Testing of the catalyst is carried out on the installation, consisting of a series-connected microreactor and a gas chromatograph. The catalyst is placed in a microreactor with a working volume of 0.07 ml, where it is activated according to the method described above. Then dicyclopentadiene is passed through a microreactor in a carrier gas (helium) stream. The analysis of the reaction products is carried out after stabilization of the catalyst by prolonged supply of DCPD until a constant degree of decomposition is achieved.

Analysis of the reaction products is carried out on a serial chromatograph type LHM-8 MD with a flame ionization detector. A separation column 2.0 m long is filled with a sorbent from 10% PEG-20M carbovax on a 1K color chromate of 0.16-0.25 mm fraction. The temperature of the thermostat columns kept at ¹²⁰ ° C followed by increasing to ^{160 °} C in order to verify the formation of high boilers. Helium is used as the carrier gas.

The catalyst fraction 0.1-0.2 mm is loaded into the microreactor in an amount of 0.1 g, DCPD is passed through the microreactor with a space velocity of 14154-42463 h ^-1 .

 The inventive method is illustrated by the following examples.

PRI me R 1 (prototype). Testing of the catalyst is carried out on the installation described above. As the catalyst using active γ-alumina brand A-1. At a temperature of 200 ^{° C} DCPD passed through the catalyst at a space velocity 28308 h ^-1. The composition of the reaction products, wt. %: CPD 9.8, DCPD 73.9, by-products 16.3.

PRI me R 2 (prototype). Testing of the catalyst is carried out on the installation described above. As the catalyst using active γ-alumina brand A-1. At a temperature of 250 ^{° C} DCPD passed through the catalyst at a space velocity 28308 h ^-1. The composition of the reaction products, wt. %: CPD 20.6; DCPD 56.7, by-products 22.7.

PRI me R 3. Testing of the catalyst is carried out on the installation described above. At a temperature of 200 ^{° C} DCPD passed through the catalyst at a space velocity 28308 h ^-1. Catalyst activation is carried out under the following conditions: activation temperature 200 ^C, the volume ratio of catalyst: hydrogen = 1: 3000, the volume ratio of catalyst: air of 1: 0.14. The composition of the reaction products, wt. %: CPD 99.2, DCPD 0.8, no by-products.

 Examples 4-20 are carried out under conditions similar to example 3, but changing in each case one of the parameters. The conditions and results are shown in table. 1 and 2.

 The results are shown in table. 1 and 2 show that an increase in the ratio of catalyst: hydrogen of more than 1: 2000 does not affect the activity of the catalyst.

As can be seen from the above examples, the use of this catalyst allows you to:
monomerization lower process temperature to 150-250 ^{° C,} which leads to a sharp decrease of energy consumption for its implementation;
increase the concentration of cyclopentadiene in the reaction products to 99.2%, almost completely converting dicyclopentadiene into the target product;
reduce production waste by eliminating adverse reactions in the synthesis of inappropriate products. (56) Copyright certificate of the USSR N 1328343, cl. C 07 C 13/15, 1987.

 USSR author's certificate N 1226798, cl. C 07 C 13/15, 1984.

 Azerbaijan Oil Industry, 1985, N 4, p. 36-39.

Claims (1)

METHOD FOR PRODUCING CYCLOPENTADIENE by catalytic depolymerization of dicyclopentadiene at elevated temperature, characterized in that, in order to increase the yield and purity of cyclopentadiene, the process is carried out at 150 - 250 ^o C in the presence of a nickel-chromium catalyst activated with hydrogen at a temperature of 150 - 200 ^o C, volume ratio catalyst: hydrogen 1: 2000 - 3000, followed by air treatment at a volume ratio of catalyst: air 1: 0.11 - 0.21.

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