Nickel-Based Ceria, Zirconia, and Ceria-Zirconia Catalytic Systems for Low-Temperature Carbon Dioxide Reforming of Methane

摘要

Carbon dioxide reforming of methane (CDRM) was studied over a variety of ZrO_2-, ceria-doped ZrO_2-, and CeO_2-ZrO_2-supported Ni catalysts. Different techniques were used to prepare supports material having different physicochemical properties, and a correlation was established to show the importance of a robust support material. Various characterization of the catalyst further established that the coking behavior of the catalyst depends on the support preparation techniques. Compared to zirconia and ceria-doped zirconia, the use of ceria-zirconia (Ce_xZr(1-x)O_2) solid solution as a support prepared by using a surfactant was found to be the most stable for low-temperature CDRM. It seems the inhibition of reactions leading to carbon deposition is prominent in systems having ZrO_2. Temperature-programmed oxidation (TPO) experiments indicated excellent resistance toward carbon formation for Ni supported on Ce_xZr_(1-x)O_2 compared with other catalysts studied. H_2-TPR (temperature-programmed reduction) analyses also showed that the stability of Ce_xZr_(1-x)O_2 solid solution is a function of its enhanced reducibility at lower temperatures as compared to either pure ceria or ceria-doped ZrO_2. Based on all the catalysts studied, 5% Ni Ce_(0.6)Zr_(0.4)O_2 was found to be the best catalyst as activity was stable for up to 100 h at 650 and 700 ℃, while at 800 ℃ the catalyst activity remained stable for more than 200 h.