Tunning Pd–Cu-based catalytic oxygen carrier for intensifying low-temperature methanol reforming

Abstract

Methanol is a competitive candidate for in-situ hydrogen supply; however, the techniques of methanol-to-hydrogen production are suffered from high reforming temperatures and catalyst deactivation. In this work, the chemical looping oxidative reforming of methanol is conducted using a Pd–Cu-based catalytic oxygen carrier (PdO–CuO–CuMn2O4). Synergistic enhancement of lattice oxygen induction and Pd–Cu alloy activation is confirmed, thereby achieving efficient methanol reforming at a temperature as low as 200 °C. Under such low temperatures, the hydrogen production rate can reach an average of 11.2 times higher than that of CuO/ZnO/Al2O3. Moreover, the catalytic oxygen carrier remains relatively satisfying redox durability after 30th cycle. SEM and AFM measurements reveal the high degree of roughness at the PdO–CuO–CuMn2O4 surface, in which the methanol activation can be effectively promoted. XRD and XPS measurements verify the formation of Pd–Cu alloy, as proved by the charge transfer from Pd to Cu. During the redox looping, Pd–Cu alloy is formed and re-separated to be PdO and CuO, thus remaining homogenous distribution of the active phase on an atomic scale. Meanwhile, the lattice oxygen also plays a crucial role in methanol activation, synergistically enhancing the low-temperature reforming of methanol. This study provides a new implication for designing functionalized catalytic oxygen carrier materials, which will substantially promote in-situ hydrogen supply for proton exchange membrane fuel cells.