Light Alkane Dehydroaromatization over Pt-Zn/HZSM-5 Catalyst with Ultralow Pt Loading

Abstract

Minimizing Pt loading in dehydroaromatization (DHA) catalysts is critical to the cost-efficient transformation of abundant light alkanes for energy and chemical production. Recent studies in our group show that Pt-Zn/HZSM-5 catalysts with Pt loading of 0.001–0.05 wt% (10–500 ppm) are highly active and stable for ethane DHA (J Am Chem Soc 144(26):11831–11839, 2022). Here, we investigated the catalytic behavior of such catalysts, especially with further decreased Pt loading (< 10 ppm), in both propane and ethane DHA. For propane DHA, we show that the bimetallic Pt-Zn/HZSM-5 catalysts with Pt loading of 50–500 ppm are significantly more active and/or stable than the monometallic counterparts. Such enhancement becomes less significant when decreasing Pt loading to ≤10 ppm. For ethane DHA, the mass-specific activity of the Pt-Zn/HZSM-5 catalysts decreases almost linearly with decreasing Pt loading from 10 to 2.5 ppm, indicating a constant molar-specific activity (TOF) of up to 132 s⁻¹ (mol_ethane/mol_Pt). This breakthrough is achieved owing to the formation of [Pt₁-Zn_n]^δ+ ensemble in the micropores of ZSM-5 zeolite.