Preparation and application of granular ZnO/Al 2O 3 catalyst for the removal of hazardous trichloroethylene

Abstract

Trichloroethylene (TCE) is a volatile and nerve-toxic liquid, which is widely used in many industries as an organic solvent. Without proper treatment, it will be volatilized into the atmosphere easily and hazardous to the human health and the environment. This study tries to prepare granular ZnO/Al 2O 3 catalyst by a modified oil-drop sol–gel process incorporated the incipient wetness impregnation method and estimates its performance on the catalytic decomposition of TCE. The effects of different preparation and operation conditions are also investigated. Experimental results show that the granular ZnO/Al 2O 3 catalyst has good catalytic performance on TCE decomposition and the conversion of TCE is 98%. ZnO/Al 2O 3(N) catalyst has better performance than ZnO/Al 2O 3(O) at high temperature. Five percent of active metal concentration and 550 °C calcination temperature are the better and economic preparation conditions, and the optimum operation temperature and space velocity are 450 °C and 18,000 h −1, respectively. The conversions of TCE are similar and all higher than 90% as the oxygen concentration in feed gas is higher than 5%. By Fourier transform infrared spectrography (FT-IR) analyses, the major reaction products in the catalytic decomposition of TCE are HCl and CO 2. The Brunauer–Emmett–Teller (BET) surface areas of catalysts are significantly decreased as the calcination temperature is higher than 550 °C due to the sintering of catalyst materials, as well as the reaction temperature is higher than 150 °C due to the accumulations of reaction residues on the surfaces of catalysts. These results are also demonstrated by the results of scanning electron micrography (SEM) and energy disperse spectrography (EDS).