The state of Pt active phase and its surrounding environment during dehydrogenation of ethane to ethylene

The efficient conversion of ethane has become more attractive recently because of the shale gas revolution. Platinum-based catalyst is the most active for direct dehydrogenation of ethane to ethylene, but it always suffers deactivation due to coke deposition and sintering of supported Pt. We have successfully synthesized a Pt-embedded inside HZSM-5 crystal catalyst (Pt@HZSM-5) by hydrothermal synthesis using Pt/SiO 2 as only silicone source, to realize excellent stability during the dehydrogenation of ethane (EDH) to ethylene. Based on various characterization results, including in-situ synchrotron XANES and EXAFS, in situ XPS, operando DRIFTS, as well as 27 Al MAS NMR, the stable Pt species with high electron density on Pt@HZSM-5 avoids the deep dehydrogenation of ethane to form coke, and the surrounding environment of Pt active phase, including newly formed HZSM-5 frameworks and its acidity, contributes to suppressing the aromatization of the formed ethylene. As synergic effects, the Pt@HZSM-5 catalyst realizes excellent stability during 50 h EDH reaction without any regenerations with relatively high ethane conversion under the serve reaction conditions (90% ethane in feed gas, 0.1 MPa, 550 °C). However, the conventional Pt/HZSM-5 catalyst exhibits dynamic transformation of Pt chemical state, particle size, and its surrounding environment, resulting in rapid deactivation induced by much more carbon deposition and aromatization of the formed ethylene.