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...

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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: batch hydrogenation The production process is to put dipentene in a batch hydrogenation reactor for hydrogenation reaction. After the raw materials and catalysts are put into the hydrogenation reactor in proportion, nitrogen and hydrogen are replaced several times, and then the pressure is increased and the temperature is raised under the stirring of the stirrer. Reaction, after several hours of reaction, after the sampling test is qualified, the material can be shut down and discharged. After recovering part of the residual hydrogen of the reaction, it is replaced with nitrogen, and the catalyst is filtered to remove the product. The separated catalyst needs to be replaced after being reused for 3 to 10 times, and the service life is short. , the number of recycling and regeneration is high, and a large amount of catalyst is consumed; in order to maintain a certain amount of gas-liquid contact and stirring effect in intermittent hydrogenation production, the hydrogen in the hydrogenation reactor accounts for about 40% of the volume. The effective volume of the hydrogenation reactor is reduced. Since the intermittent hydrogenation production process includes multi-step operations such as feeding, nitrogen hydrogen replacement, temperature rise, pressure increase, hydrogenation reaction, filtration, pressure reduction, and temperature drop, the procedures are complicated, time-consuming, and efficient. Low energy consumption and high energy consumption; under the same production scale, the hydrogenation reactor and related auxiliary equipment are required to be large in size, occupy a large space, and have high labor intensity; in batch hydrogenation production, each time the reactor is fed into and out of the reactor, gas Replacement, resulting in a large amount of waste of hydrogen and nitrogen; due to the existence of the above problems, the automation control in production is difficult, the pressure and temperature are unstable, resulting in difficult control of the cis-trans ratio of menthane, poor stability of product quality, and difficulty in scaling up the production scale; ( 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 low-priced non-precious metal catalyst is used, because the service life is generally only 1 month, the longest is also But about 3 months, make the production operation process become loaded down with trivial details, and production cost is also higher; The 2nd, according to the purposes of the fragrance intermediate and synthetic rubber of p-menthane product, think that cis-p-menthane high then carry out the following reaction High activity, so in addition to high yield of p-menthane products, good selectivity of cis-p-menthane is also required in production

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