Boosted production of aromatics by catalyzing upgrade pyrolysis vapors from lignite over Sn-Ga/HZSM‑5 catalysts

Abstract

A multifunctional catalyst of Ga-Sn anchored on hierarchical HZSM‑5 (Sn-Ga/AT0.2H5) was investigated in catalytic reforming of lignite pyrolysis volatile. A strong synergy was observed between Ga and Sn for the production of aromatics. The addition of Ga into AT0.2H5 remarkably promoted the selectivity of aromatics including benzene, toluene, ethylbenzene, xylene and naphthalene (BTEXN) compared to pure HZSM-5 (H5). The BTEXN yields increased to 24.1 mg/g over monometallic 5%Ga/AT0.2H5, in which the benzene yield was attained to 14.8 mg/g. With the introduction of Sn, the yield of aromatics was further improved to 25.1 mg/g. An explanation of this scenario was that introduced active metals could enhance the transformation of cyclic intermediates into aromatics and H5 support with an appropriate concentration of the acid sites provided acidic protons for aromatization. Additionally, the bimetallic Sn-Ga/AT0.2H5 exhibited higher stability with the yield of BTEXN maintained over 22 mg/g after three recycle experiments, which offered an efficient strategy to prolong the catalyst lifetime.