Method for producing phenol by oxidizing benzene through nitrous oxide

Abstract

The invention relates to a process method for producing phenol by selectively oxidizing benzene through nitrous oxide, comprising the following steps of: placing a Fe-ZSM-5 molecular sieve catalyst on a distribution plate inside a fixed fluidized bed reactor; firstly activating the Fe-ZSM-5 molecular sieve catalyst by using helium at 400-600 DEG C; then introducing a gas containing the nitrous oxide and the benzene from the lower end inside the fixed fluidized bed reactor at normal pressure; controlling the reaction gas velocity of the gas between 0.040m / s and 0.072m / s through the gas distribution plate so that catalyst granules contact with the gas in a suspended state in the fixed fluidized bed reactor to carry out continuous reaction at the temperature between 300 DEG C and 500 DEG C and the normal pressure, wherein the mol ratio of the raw material benzene / N2O is between 4 and 16; and condensing and separating reaction products to obtain the phenol. The invention enables the Fe-ZSM-5 molecular sieve catalyst to contact with reaction fluids in the suspended state by utilizing the fixed fluidized bed reactor, therefore sliding velocity higher than terminal granule velocity exists between the gas and a solid; and in addition, the invention not only has very high contact efficiency, but also is beneficial to carrying out mass transfer between the gas and the solid and desorbing a product, i.e. the phenol, thereby alleviating the coking deactivation of the Fe-ZSM-5 molecular sieve catalyst.

Description

technical field [0001] The present invention relates to a method for effectively utilizing nitrous oxide as an oxidizing agent. In particular, it relates to a method for selectively oxidizing benzene with nitrous oxide to produce phenol. Background technique [0002] Nitrous oxide, chemical formula N 2 O, commonly known as laughing gas, not only can seriously destroy the ozone layer, but also has a strong greenhouse effect, and the elimination of nitrous oxide is of great significance to environmental protection. The current methods of eliminating nitrous oxide can be divided into pyrolysis, catalytic decomposition and recycling. If the method of simple decomposition is used to process nitrous oxide, it will not only cost a lot of money and energy, but also waste nitrous oxide resources. Therefore, in recent years, a lot of research has been carried out around the recovery and utilization of nitrous oxide at home and abroad. It is of great significance to use nitrous oxid...

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Problems solved by technology

However, the disadvantage of this process is that the catalyst activity and stability are relatively poor.

Due to the strong adsorption of the product phenol on the surface of the catalyst, it is not easy to desorb from the active sites on the surface of the catalyst, further deep oxidation reaction occurs to form carbon deposits, and the catalyst is rapidly deactivated, which restricts the industrial application of this process technology

[0004] The common problem in the nitrous oxide one-step oxidation of benzene to produce phenol reported in the above literature is that all catalysts used are facing the problem of rapid deactivation, mainly due to the strong adsorption of active sites or acidic sites on the surface of the catalyst to the product phenol, etc., resulting in phenol deactivation. Further deep oxidation forms carbon deposits on the surface of the catalyst and causes catalyst deactivation. In this field, current research generally starts with catalyst preparation and modification to solve this problem, but there is no significant effect

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