Catalytic cracking of toluene using a biochar derived catalyst

Abstract

This research investigated char naturally produced inside the gasifier, as a low cost catalyst, to decompose toluene as a model tar compound from the temperature range of 600-900°C. The reaction kinetics found from 650 to 900°C gave an activation energy of 90 kJ/mol for toluene decomposition (compared to 80.24 kJ/mol for Ni/Mayenite and 196 kJ/mol for olivine). The catalytic activity of char for toluene decomposition was comparable to other commercially available catalysts. It is theorized that metals in the char catalyzed a free radical reaction in which benzene, CO₂ and CH₄ was formed as end products. Additionally, when char was loaded with iron (9.89%, 13% and 18.7% by weight), the activity increased and the temperatures required for almost complete conversion were lowered from 900 to 800⁰C. The activation energy found for the iron loaded char (18.7%) was 49 kJ/mol. The results from this research may be used to design a catalytic cracking process using biochar catalysts for tars downstream of a gasifier or inside the gasifier and potentially replace energy intensive and costly processes.