Performance of H‐ZSM‐5‐supported bimetallic catalysts for the combustion of polluting volatile organic compounds in air

The performance of H‐ZSM‐5‐supported bimetallic catalysts with chromium as the base metal in the combustion of ethyl acetate and benzene is reported. A reactor operated from 100 to 500 °C at a gas hourly space velocity (GHSV) of 32 000 h −1 was used for study of the activity. A combination of 1.0 wt% chromium and 0.5 wt% copper yielded a catalyst (Cr 1.0 Cu 0.5 /Z) with improved conversion and carbon dioxide yield. Cr 2 O 3 (Cr 3+ ) and CuO (Cu 2+ ) were the predominant metal species in the catalyst. In agreement with the Mars–van Krevelen model, improved reducibility of Cr 3+ in the presence of Cu 2+ led to an improvement in activity. The copper content in Cr 1.0 Cu 0.5 /Z also favored the formation of deep combustion products. Condensation and subsequent growth of coke precursors in the catalyst pores led to the formation of a softer and less aromatic coke fraction while dehydrogenation activity on acid sites formed a harder and more aromatic coke fraction. The use of Cr 1.0 Cu 0.5 /Z favored the formation of lower molecular weight intermediates, leading to reduction in formation of softer coke. Copyright © 2005 Society of Chemical Industry