Screening of mono and bimetallic catalysts for the dry reforming of methane

Abstract

A series of nine different mono and bimetallic catalysts based on Ni, Rh and Pd supported on γ-Al2O3 or CeO2-Al2O3 was screened and compared in terms of activity and stability for the dry reforming of methane (DRM) reaction. All catalysts were prepared by the incipient wetness impregnation (IWI) method and characterized by XRD, XRF, TPR, H2 chemisorption and N2 physisorption. The used techniques aimed at determining crystalline phases, metal loading and dispersion and textural properties, which are properties that will affect the catalytic performance. The reactions were carried out in a fixed bed quartz reactor with temperatures ranging from 700° to 800 °C, WHSV 30 L gcat−1 h−1 and CH4:CO2 = 1 for periods of at least 48 h. All monometallic Ni based catalyst suffered from deactivation by coke deposition in the first hours of reaction at 700 °C. However, the original catalytic performance of these catalysts was restored after a regeneration treatment. At higher temperatures (800 °C), the 15%Ni/CeO2-Al2O3 catalyst presented no obvious signs of deactivation over the course of 48 h. Monometallic Pd/CeO2-Al2O3 catalysts, despite presenting higher turnover frequencies (TOF) when compared to monometallic and bimetallic Ni based catalysts, lost activity due to coke deposition. Both monometallic Rh based catalysts (0.5%Rh/CeO2-Al2O3 and 1%Rh/CeO2-Al2O3) presented a remarkable activity and stability with no signs of deactivation for 96 h TOS. The 0.5%Rh/CeO2-Al2O3 catalyst presented the highest TOF values among all screened catalyst with TOFCH4 of 9.9 s−1 and TOFCO2 of 12 s−1.