Method and device for continuously producing p-menthane by utilizing bipentene

Abstract

The invention discloses a method and a device for continuously producing p-menthane by utilizing bipentene. The method comprises the following steps: (1) placing a catalyst into a fixed bed reactor; replacing the air by nitrogen, preheating hydrogen, introducing the hydrogen into a gas and liquor mixer, preheating the bipentene in a liquor preheater, introducing the preheated bipentene into the gas and liquor mixer, evenly mixing in the gas and liquor mixer, and introducing into the fixed bed reactor for hydrogenation; (2) cooling the materials subjected to hydrogenation reaction; and (3) carrying out gas-liquid separation on the cooled reaction materials to obtain the menthane liquid product, returning the separated hydrogen to the fixed bed reactor for hydrogenation. The invention also comprises the device for implementing the method for continuously producing the p-menthane by utilizing the bipentene. In the invention, the traditional suspension bed intermittent process is changed into a fixed bed continuous hydrogenation production process, which is beneficial for improving the unstable state in hydrogenation production, improves the working efficiency, is convenient for adopting an automatic control system in the production process, is beneficial for reducing man-made operation deviation and is convenient for amplifying the production scale. The invention has the advantages of stable product quality, safe operation, high efficiency and low consumption.

Description

technical field [0001] The invention relates to a continuous production method and device for preparing p-menthane from dipentene. Background technique [0002] Dipentene is a class of monocyclic terpene by-products (including p-mentene, terpinene, p-cymene, etc., collectively referred to as dipentene) when camphor and terpineol are synthesized from forestry products turpentine. Most of pentene is used as paint solvent and its value is not high. Therefore, how to develop and utilize dipentene to make more valuable products is a major issue. Catalytic hydrogenation of dipentene to produce p-menthane, which can then be used as a fragrance intermediate and then processed into a synthetic rubber initiator or other products, can increase the added value of turpentine processed products. [0003] At present, the industrial production of p-menthane from dipentene has the following main problems: (1) Problems in the batch hydrogenation production process: the batch hydrogenation p...

AI Technical Summary

Problems solved by technology

[0003] At present, the industrial production of p-menthane from dipentene has the following main problems: (1) Problems in the batch hydrogenation production process: the batch hydrogenation production process is to place dipentene in a batch hydrogenation reactor Carry out the hydrogenation reaction. After the raw materials and catalysts are put into the hydrogenation reactor in proportion, several times of nitrogen and hydrogen replacement are carried out, and then the reaction is carried out by raising the pressure and temperature under the stirring of the agitator. After several hours of reaction, the sampling test is qualified before the shutdown Recover part of the reaction residual hydrogen and replace it with nitrogen, filter and remove the catalyst to obtain the product, the separated catalyst needs to be replaced after repeated use for 3 to 10 times, the service life is short, the number of recovery and regeneration is high, and the catalyst is consumed in large quantities; in intermittent hydrogenation production In order to maintain a certain amount of gas-liquid contact and stirring effect, the hydrogen in the hydrogenation reactor accounts for about 40% of the volume. In this way, the effective volume of the hydrogenation reactor is reduced. Due to the batch hydrogenation production process Including multi-step operations such as feeding, nitrogen and hydrogen replacement, heating, boosting, hydrogenation reaction, filtration, depressurization, and cooling, the procedures are complicated, time-consuming, low in efficiency, and high in energy consumption; under the same production scale, hydrogenation is required Reactors and related auxiliary equipment are large in size, occupy a large space, and have high labor intensity; in intermittent hydrogenation production, gas replacement must be carried out every time the material is fed into and out of the reactor, resulting in a large waste of hydrogen and nitrogen; due to the existence of the above problems, The automation control in production is difficult, and the pressure and temperature are unstable, which makes it difficult to control the cis-trans ratio of menthane, the stability of product quality is poor, and the production scale is difficult to expand; (2) At present, there are problems in the continuous fixed-bed hydrogenation process: First, the price of the precious metal catalyst used is high; even if a non-precious metal catalyst with a lower price is selected, the service life is generally only 1 month, and the longest is only about 3 months, which makes the production operation process cumbersome. The cost is also relatively high; the second is that according to the use of menthane products as spice intermediates and synthetic rubbers, it is believed that the cis-menthane is highly active in the following reactions, so in production, in addition to requiring high yields of menthane products , also requires good selectivity of cis-to-menthane

Images