Preparation of highly stable bimetallic Ni–Cu catalyst for simultaneous production of hydrogen and fish-bone carbon nanofibers: Optimization, effect of catalyst preparation methods and deactivation

This paper presents the preparation of highly stable nano-porous Ni–Cu catalysts for simultaneous production of COx–free hydrogen and carbon nano-fibers. The main features of this work focuses on the optimization, methods of catalyst preparation and application of an experimental model for deactivation. The fresh catalysts and the deposited carbon were characterized by SEM, TEM, XRD and Raman spectroscopy. Whatever to be the preparation methods, performance tests showed that the presence of Cu as promoter in Ni–Cu–MgO catalysts, enhanced the catalytic activity, substantially at higher temperatures with the best result obtained for Ni–Cu–MgO catalyst prepared by one step sol- gel method, reaching a hydrogen concentration of 70 vol% (160.51 mol H2/mol Ni-1 h) and a smaller value of ID/IG (less imperfection) for produced carbon nano-fibers at 670 °C. Detailed rate-based model for deactivation of catalyst was found to be dependent on the time, reaction temperature and partial pressure of methane and indicated that the reaction of deactivation could be modeled by a simple hyperbolic model.