A kind of benzene oxidation method

Abstract

The invention discloses a benzene oxidation method. The method comprises the step of enabling a liquid mixture to sequentially flow through a first catalyst bed layer and a second catalyst bed layer under oxidation reaction conditions, wherein the liquid mixture contains benzene, an oxidant and an optional solvent, the first catalyst bed layer and the second catalyst bed layer each is loaded with titanium silicalite molecular sieves, and the superfacial velocity of the liquid mixture flowing through the first catalyst bed layer is lower than that of the liquid mixture flowing through the second catalyst bed layer. According to the method, in a long-time continuous operating process, the single-pass service lives of the titanium silicalite molecular sieves as a catalyst can be effectively prolonged, the regeneration frequency is lowered, the production efficiency of a device is increased, and the operating cost of the device is reduced; and the availability of the oxidant is relatively high. In addition, the method is high in operability, in a practical application process, two reaction zones are arranged in series, and the inner diameter of the reaction zone located at upstream is enabled to be greater than that of the reaction zone located at downstream.

Description

technical field [0001] The present invention relates to a kind of benzene oxidation method. Background technique [0002] Phenol is an important bulk chemical raw material product in the current organic chemical industry. In 2000, the world demand for phenol has exceeded 66Mt, which is mainly used to prepare bisphenol A, phenolic resin and pharmaceutical intermediates. In addition, phenol and its derivatives are also used in the production of paints, dyes, explosives, petroleum additives, wood preservatives, etc. [0003] At present, the main sources of phenol in the industry, except for extraction from coal tar or petroleum distillates, are chemical synthesis methods. The main synthesis methods include sulfonation method, Raschig-Hooker method, chlorobenzene hydrolysis method, and toluene oxidation method. , Cyclohexane oxidation method and cumene oxidation method (also known as cumene method). Except for the toluene oxidation method, other methods are multi-step indirec...

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Problems solved by technology

[0005] However, when titanium-silicon molecular sieves are used as catalysts to catalyze the oxidation of benzene to phenol, the catalytic activity of titanium-silicon molecular sieves tends to decrease with the prolongation of the reaction time, resulting in a significant decrease in the selectivity of the target oxidation product.

When the reaction is carried out in a fixed-bed reactor, due to the reduction of the catalytic activity of the titanium-silicon molecular sieve, the titanium-silicon molecular sieve needs to be regenerated inside or outside the reactor, resulting in shutdown of the reactor, thereby affecting production efficiency and increasing the operating cost of the device

[0006] Moreover, when the regenerated catalyst is put into operation again, especially after being regenerated in the reactor, the activity of the catalyst fluctuates greatly and takes a long time to stabilize, resulting in a decrease in the selectivity of the target oxidation product, which will not only reduce The operating efficiency of the device, and the subsequent separation and purification process is required to adjust the operating conditions, which increases the complexity of the operation; at the same time, it is also necessary to combine operations such as increasing the reaction temperature to achieve a smooth operation of the reaction, but these measures often accelerate catalyst loss. live

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