陶瓷膜分布器强化氧气氧化苯酚羟基化反应

Enhanced phenol hydroxylation with oxygen using a ceramic membrane distributor

采用浸渍法制备CuO/TiO2催化剂,利用X射线衍射、透射电镜、程序升温还原等技术对催化剂进行了表征,结果表明,CuO以分散态和晶体两种形式存在,且与载体有强的相互作用. 以陶瓷膜为分布器控制氧气的进料,进行了CuO/TiO2催化氧气氧化苯酚羟基化反应. 与直接通入氧气方式相比,采用孔径为0.5μm的陶瓷膜控制进氧,可使苯二酚收率提高13%,这主要是由于采用陶瓷膜作为氧气进料分布器可以提供大量具有微小尺寸的氧气气泡,提高体积溶氧系数,增强气液传质效果. 在优化的反应条件下,苯二酚收率达2.5%. 对使用后的陶瓷膜进行扫描电镜表征,发现陶瓷膜具有良好的稳定性.

A CuO/TiO2 catalyst was prepared by impregnation and characterized by X‐ray diffraction,transmission electron microscopy,and temperature‐programmed reduction.Two types of dispersed species formed on the TiO2 surface,which were possibly isolated and polymeric CuO species.The CuO catalyst interacted strongly with the TiO2 support.A porous ceramic membrane was used as a distributor to control the supply of oxygen in phenol hydroxylation over the CuO/TiO2 catalyst.Compared to a direct feed of oxygen without a membrane,the yield of dihydroxybenzene（DHB） increased by 13% using a porous ceramic membrane with a pore size of 0.5μm as an oxygen distributor.This is because the membrane distributor produced numerous small oxygen bubbles,increasing the volumetric oxygen transfer coefficient and gas‐liquid mass transfer.Optimizing reaction conditions resulted in a yield of DHB of 2.5%.Scanning electron microscope observation of the used ceramic membrane showed that it possessed excellent thermal and chemical stability.