Catalytic performance and intermediates identification of trichloroethylene deep oxidation over Ru/3DOM SnO2 catalysts
SnO 2 is widely used in catalysis owing to its oxygen vacancies, reducible oxygen species, and acidity. In this work, Ru nanoparticles (NPs) supported on three-dimensionally ordered macroporous (3DOM) SnO 2 ( x Ru/3DOM SnO 2 , Ru loading ( x ) = 0.09–1.65 wt%) were fabricated via the polyvinyl alcohol-protected reduction routes, and their catalytic activities were determined for trichloroethylene (TCE) and/or toluene oxidation. It was shown that the 0.98Ru/3DOM SnO 2 sample exhibited the best activity and good thermal stability, with the temperature ( T 90% ) and apparent activation energy at a TCE (1000 ppmv) conversion of 90% being 300 °C and 44 kJ/mol at space velocity = 40,000 mL/(g h), respectively. Trichloromethane, carbon tetrachloride, tetrachloroethylene, and trichloroacetaldehyde hydrate were the main intermediates in TCE oxidation. The high catalytic performance of 0.98Ru/3DOM SnO 2 was attributed to the presence of hydroxyl groups adsorbed at the oxygen vacancies, strong O 2 adsorption ability, good low-temperature reducibility, and strong interaction between Ru NPs and 3DOM SnO 2 . In addition, a catalytic mechanism over x Ru/3DOM SnO 2 was proposed under dry and humid conditions. The introduction of H 2 O could block some of the reaction pathways from inhibiting the production of C 2 Cl 4 , reduce formation of some by-products (e.g., CH 2 Cl 2 , CH 3 COOH, and C 2 H 2 Cl 2 ), promote removal of the chlorine species, and generate a greater amount of HCl and a smaller amount of Cl 2 . Furthermore, introducing toluene into the TCE stream could generate smaller amounts of organic chlorine by-products and greater amounts of inorganic chlorine products (HCl and Cl 2 ). We are sure that this work can provide a guideline for the industrial application of supported Ru catalysts in the removal of Cl-containing volatile organic compounds.
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