Crucial support effect on the durability of Pt/MgAl2O4 for partial oxidation of methane to syngas

Abstract

Catalyst durability is one of the major problems hindering the commercialization of partial oxidation of methane (POM) for syngas production. We report that a Pt/MgAl2O4-HS catalyst with the MgAl2O4-HS support being synthesized via hydrolysis solvothermal (HS) method demonstrates high stability for POM during a 500 h life testing at 900 °C without detectable coke formation, while a Pt/MgAl2O4-CP counterpart in which MgAl2O4 was prepared by an optimized co-precipitation (CP) method exhibits continuous deactivation accompanied by coking. Using a suite of characterizations incluidng BET, H2 chemisorption, XRD, STEM, TEM, TG/DTA and TPD of NH3 and CO2, we reveal that the high catalytic durability of the Pt/MgAl2O4-HS is due to the spinel surface of MgAl2O4-HS that can efficiently stabilize Pt against sintering. The Pt/MgAl2O4-CP, however, has defect Al2O3 or MgO-like species on the MgAl2O4-CP surface, inhibiting its capability to stabilize Pt. We confirm that the POM reaction undergoes a combustion-reforming pathway by monitoring the temperatures and gaseous product compositions along the catalyst bed. These results provide guidance for rational design of a longevity catalyst for POM process.