Ethane and propane dehydroaromatization on Pt/HZSM-5 catalyst: Influence of Pt loading ≤ 500 ppm

Abstract

Understanding the influence of ppm level Pt loading on catalytic behavior is critical to the design of efficient catalysts with minimized Pt utilization. Here we investigate the influence of Pt loading (≤ 500 ppm) in HZSM-5 on the catalytic behavior of ethane and propane dehydroaromatization (DHA). We show that the activity, selectivity, and stability of the catalyst are highly dependent upon Pt loading. While 500 and 100 ppm catalysts show nearly the same turnover number (TON) in both ethane and propane DHA, the TON decreased and the average rate of coking (per gram catalyst basis) increased with decreasing Pt loading to 50 ppm. The 50 ppm Pt/HZSM-5 failed to form the optimized [Ptm-Hn]n+ adduct due to the limited Pt availability at the nearby T12 and T8 sites. Consequently, the minimum Pt loading is between 50 and 100 ppm for the maximized intrinsic metal functionality for light alkanes DHA over the monometallic Pt/HZSM-5 catalyst.