UV-A-induced autocatalytic oxidation of TCE in fixed-bed reactor with transparent silica-gel adsorbent

We report on a new approach to the photocatalytic decomposition of gaseous pollutants on inherently non-active nanoporous silica-gel substrate in fix-bed continuous-flow reactor under UV-A illumination. The pollutants and oxidized products (CO/CO2) concentrations were permanently monitored in the current study. The observed effect is of autocatalytic nature and related to a molecular chlorine accumulation and retention onto the strongly adsorbing material with a large BET surface (∼330 m2/g). The chlorine accumulation stage delays the material activity onset during the first reactor run with trichloroethylene (TCE). In subsequent runs, the material develops photocatalytic activity immediately at UV-A illumination. The approach was tested on non-chlorinated hydrocarbons ethylene and methanol that show a high decomposition yield after pre-treatment with TCE or dichloroacetyl chloride (DCAC).

Graphical abstractInherently non-active nanoporous silica-gel develops high photocatalytic activity toward gaseous pollutants decomposition after pre-treatment with trichloroethylene (TCE) or dichloroacetyl chloride (DCAC). This effect is autocatalytic by nature and related to a molecular chlorine accumulation and retention onto a strongly adsorbing material with large BET surface (∼330 m2/g). The chlorine accumulation stage delays the material activity onset during the first reactor run. In subsequent runs, the material develops photocatalytic activity immediately at UV-A illumination. The approach was tested on chlorinated (TCE) and non-chlorinated (ethylene and methanol) hydrocarbons.Figure optionsDownload full-size imageDownload as PowerPoint slide