Method of preparing cyclopentene by continuous hydrogenation of cyclopentadiene

Abstract

The continuous cyclopentadiene hydrogenating process to prepare cyclopentene is one continuous catalytic hydrogenation reaction of the mixture of cyclopentadiene, solvent and hydrogen in a fixed bed catalyst bed. The catalyst includes gamma-Al2O3 as carrier and Pa as active component. The solvent is any one of benzene, toluene, cyclohexane, ethanol, methanol, tertiary amyl alcohol and tertiary butyl alcohol. The molar ratio between cyclopentadiene and hydrogen is 1 to 1.5-3.5, and the reaction system has pressure of 0.9-1.5 MPa and temperature of 30-55 deg.c. The reacted liquid is discharged partially and externally circulated partially with the weight ratio being 1 to 6-12, and the externally circulated liquid after being cooled is mixed with cyclopentadiene material and solvent before being mixed with hydrogen in venturi ejector, atomized into gas-liquid mixture and reacted in the catalyst bed. The catalyst load is 4-7 / hr accounted in liquid phase material, and the reacted heat is transferred via external circulation.

Description

Technical field [0001] The invention relates to a method for preparing cyclopentene by selective hydrogenation of cyclopentadiene. Background technique [0002] Cyclopentene is an intermediate for many fine chemical products. For example, it can be used to produce high value-added pharmaceutical intermediates such as cyclopentanol, bromocyclopentane, chlorocyclopentane, and cyclopentane acid. Cyclopentene is also a poly The main raw material of cyclic olefin polymer. In the prior art, cyclopentene can be obtained by a variety of methods, but the method of producing cyclopentadiene by hydrogenation has the most industrial application prospects. For example, US Patent 3,994,986 uses dicyclopentadiene to depolymerize into cyclopentadiene, and then two-stage hydrogenation to continuously produce cyclopentene. The tubular reactor is used as the hydrogenation reactor, the molar ratio of hydrogen to cyclopentadiene in the first stage is (1~1.5):1, and the ratio in the second stage is (1...

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Problems solved by technology

Since the cyclopentadiene hydrogenation reaction is a strong exothermic reaction, the catalyst bed is prone to runaway temperature during the catalytic hydrogenation process, resulting in catalyst deactivation

In the prior art, the method of installing heat exchange devices in the hydrogenation reactor is mostly used to remove a large amount of reaction heat. The defect of this method is that the uniformity of cooling in the reactor is limited to a certain extent.

It is speculated that there is a local excessive temperature rise in the catalyst bed, which causes partial catalyst deactivation, and cyclopentadiene is easily dimerized to form dicyclopentadiene in this high temperature region, which will reduce the concentration of cyclopentene. yield

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