In situ auto-gasification of coke deposits over a novel Ni-Ce/W-Zr catalyst by sequential generation of oxygen vacancies for remarkably stable syngas production via CO2 -reforming of methane

Coking is the major bottleneck in the development of stable catalysts in thermal catalysis. Oxygen vacancies (V-o) play a vital role in realizing the in situ gasification of carbon deposits and the activation of reacting gases, thus leading to the stable activity. Ceria is a potential candidate that provides plentiful V-o, however, V-o annihilated as a result of thermal aging. In this study, by using a novel Ni-Ce/W-Zr catalyst, thermal aging turned as a 'blessing in disguise', because a tremendous amount of V-o was sequentially generated following the thermal aging. The findings were substantiated by TEM, XRD, BET, XPS, Raman spectroscopy, TGA, TPO, TPR and CO2-TPD. In the early stages, CeO2 and ZrO2 formed the solid solution, supplying the oxygen vacancies. Subsequently, Ce-2(WO4)(3) comes into play as a result of thermal aging and furnish the abundant oxygen vacancies. Thus, the sequential generation of oxygen vacancies suppressed the coke formation on one hand, whereas tangibly controlled the sintering of metallic species on the other hand. Consequently, Ni-Ce/W-Zr catalyst demonstrated the remarkable activity and outstanding stability (100 h).