Calcination temperature influence on the catalytic performance of Ni/CeO_2-ZrO_2 for low temperature steam reforming of methane

摘要

Steam reforming of methane (SRM) is the primary method to produce hydrogen.rnCommercial Ni-based catalysts have been optimized for SRM with excess steam (H_2O/CH_4 > 3) atrnhigh temperatures (> 700℃). However, commercial catalysts are not suitable under severe reactionrnconditions such as less steam (H_2O/CH_4 ≤ 3) and low temperature (500℃). In this study, a coprecipitationrnmethod was employed to prepare 15%Ni-Ce0.8Zr0.2O2 catalysts under differentrncalcination temperature (450℃, 550℃, 650℃, 750℃) for SRM. Structures of the catalysts werernsystematically examined by N2 adsorption/desorption, X-ray diffraction (XRD) and hydrogenrntemperature programmed reduction (H_2-TPR) techniques. The activities of these catalysts werernevaluated at the reaction condition of 500℃, 1atm, GHSV of 30000 mL/gcat∙h, the molar ratio ofrnmethane to steam is 1:3. Results showed the 15%Ni-Ce0.8Zr0.2O2 catalyst calcined at 650℃ exhibitedrnsuperior catalytic activity with 47% CH_4 conversion and 63% for H_2 yield and the activity wasrnmaintained without significant loss after 100 h running. The remarkable catalytic performance mightrnbe due to the balance between the relatively large surface area and the suitable interaction betweenrnNi and CeO_2–ZrO_2.