Non-oxidative methane aromatization by bimetallic (La, Co, Pd, and Pt) M-Zn/HZSM-5: Impact of propane addition

Abstract

The non-oxidative aromatization of methane was studied over M-Zn/HZSM-5 (M = La, Co, Pd, and Pt) catalysts using propane as a co-reactant. The catalysts were characterized by BET, SEM, NH3-TPD, and XRD techniques. Catalytic tests were performed in a fixed-bed reactor at 823 K using a mixture of methane, propane, and nitrogen with ratio of 6/1/1.3, respectively. Propane conversion was above 50% and remained stable in the first 12 hours on stream; however, the methane conversion rapidly dropped from a high of about 10% to zero within 4 hours, implying the absence of a stoichiometric reaction between the reactants. Both zinc and the second metal (M) had a benefficial effect on aromatic selectivity, and Pt-Zn/HZSM-5 exhibited the highest aromatic yields and catalyst stability. The results of the present study showed that co-feeding of methane with propane cannot successfully induce methane to participate in aromatization reactions.