Heterogeneous cracking of catechol under partially oxidative conditions

Heterogeneous cracking of catechol over the temperature range of 350–650 °C and under partially oxidative conditions was studied using nano-particle iron oxide. We employed a flow tube reactor set-up for heterogeneous cracking, a molecular beam mass spectrometer for the real time sampling and measurement of cracking products, and factor analysis to deconvolute the complex chemistry. The effects on conversion and products distribution of varying process parameters such as catechol feed rate, oxygen concentration, and temperature were considered. Thermal decomposition of catechol begins at above 500 °C. In the presence of the iron oxide, however, catechol significantly decomposes at temperatures as low as 350 °C. The formation of carbon dioxide and water was promoted at the lower catechol feed rates. Higher catechol feed rates suppressed the conversion and enhanced the formation of single ring aromatic products, especially the formation of an aromatic ketone, indanone (m/z 132, C9H8O), through gas-phase secondary reactions. Increasing oxygen concentration up to 21%, however, completed the cracking of catechol with increasing formation of carbon dioxide and water even at 350 °C for a high catechol feed rate. The iron oxide was deactivated after being exposed to the vapor of catechol at lower temperatures (between 350 and 400 °C). However, it retained its activity at temperatures above 450 °C. High-resolution transmission electron microscopy was used to characterize the iron oxide nano-particles at various reaction conditions.