Synthesis and characterization of Zr-promoted Ni-Co bimetallic catalyst supported OMC and investigation of its catalytic performance in steam reforming of ethanol

Abstract

This article presents simple method for the OMC-6%Ni-6%Co (ordered mesoporous carbon containing Ni and Co metallic nanoparticles) catalyst synthesis with high surface area and more proper bimetallic nanoparticle dispersion; prepared successfully by soft template hydrothermal method and different zirconium loadings (0.5, 1, 2 wt %) accomplished by impregnation method, which was known as a desired method for the metal dispersion. The catalysts with/without promoter, were characterized by XRD, FTIR and N2 adsorption-desorption isotherms, FESEM, EDS, EDS mapping, HRTEM and TPR techniques and investigated in steam reforming of ethanol (SRE) at 250–400 °C. XRD and BET results indicated that zirconium addition more than 0.5% wt, decreased the average mesopore diameter of catalysts, total pore volume and particles size. Also, it was stated that Ni2+ and Co2+ were caught by the RF/F127 network and further reduced into metallic Ni and Co nanoparticles during the carbonization. The Ni and Co nanoparticles were well-dispersed in the OMC walls. FTIR spectroscopy revealed that F127 left the structure and formed the porous structure. TPR analysis of OMC-6%Ni-6%Co/2%Zr sample, indicated that the sample is reduced easily at low temperatures. FESEM and HRTEM images showed that carbon was precipitated in the CNT form on spent catalyst samples surfaces and confirmed the position of Ni and Co bimetallic nanoparticles on the CNTs tip in the OMC-6%Ni-6%Co/2%Zr sample. 2% Zr-promoted bimetallic catalyst revealed appropriate catalytic performance for SRE, such as high activity, hydrogen yield and proper stability due to the synergistic catalysis of cobalt and nickel. Also, effective factors, such as H2O/EtOH molar ratio and gas hourly space velocity (GHSV) were investigated on the OMC-6%Ni-6%Co/2%Zr catalyst sample.