Steam reforming of toluene: Impacts of externally added oxygen-containing intermediates on property of coke

Abstract

Toluene is a typical tar compound resulting from biomass gasification. Toluene reforming could generate abundant carbonaceous intermediates that easily aggregate to form coke. Herein, the co-reforming of toluene with methanol or formic acid is conducted, aiming to understand impacts of oxygen-containing intermediates from dissociation of methanol or formic acid on coking tendency and properties of coke formed. The results indicated that the coke percentage in the used catalyst from 34.7% in toluene reforming to 14.7% with co-addition of formic acid while 22.3% with addition of methanol. This results from presence of abundant oxygen-containing intermediates (COx and ∗OH) generated from the dissociation of methanol or formic acid, which effectively gasify the C=C species from toluene. Additionally, dissociation of formic acid generates intermediates bearing the C=O functionality that involve in polymerization, forming amorphous coke of aliphatic nature and high tendency to oxidation, which is opposite to that of co-feeding methanol.