Method for preparing phenylethylene by ethylbenzene gas-phase dehydrogenation and refining product of phenylethylene

Abstract

The invention relates to a method for preparing styrene through the gas-phase dehydrogenation of ethylbenzene and refining a product. The method comprises the following steps: ethylbenzene as a raw material is heated and gasified in the presence of water; the ethylbenzene is subjected to gas-phase catalytic dehydrogenation reaction; the product of dehydrogenation reaction is condensed and is subjected to oil-water separation to obtain a coarse product; the coarse product is rectified to remove light composition impurities; the coarse product is rectified to remove the ethylbenzene; the ethylbenzene returns to a dehydrogenation material system for recycling; and the coarse product is rectified to remove heavy composition impurities so as to obtain the refined product of the ethylbenzene. The method is characterized in that a gas-phase material in the top of a tower for rectification and ethylbenzene removal is used as a heating medium and carries out heating on the ethylbenzene as the raw material and water so as to gasify the ethylbenzene. Compared with the prior method of multistage transformation heat integration for reclaiming heat energy, the method has the advantages that in the process of rectification and ethylbenzene removal, the reclaiming rate of heat energy is higher and can generally reach between 60 and 90 percent; and the method adopts single-tower operation for the ethylbenzene removal, and has simple process control as well as easy and stable operation. The method is in particular suitable for reconstructing the prior device.

Description

technical field [0001] The invention relates to a method for preparing styrene by ethylbenzene gas-phase dehydrogenation and its product refining method, in particular to a method for preparing styrene by ethylbenzene gas-phase dehydrogenation and its product refining by adopting a sequential separation process for product refining. Background technique [0002] Styrene is an important basic organic raw material, and the materials made from it have important uses in the fields of automobile manufacturing, household appliances, textiles, building materials, light industry, and toys. The dehydrogenation of ethylbenzene to styrene is currently the leading industrial production method. The raw material ethylbenzene is gasified in the presence of water (as a heat carrier), and further steam is used to provide the heat required for the reaction to carry out gas-phase catalytic dehydrogenation reaction. A fixed-bed reactor is usually used, and the active components of the commonly ...

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Problems solved by technology

But in fact, too many stages lead to a decrease in practical value due to the greatly increased complexity of equipment and operating processes. In the prior art, two-stage pressure-swing heat integration is generally used to recover ethylbenzene and styrene separation process. Heat energy, that is, the rectification separation process is carried out in two rectification towers, and the recovery rate of heat energy can reach 40-50% at most

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