3.2. Catalytic performance study toward dry reforming of methane
3.2.1. Effect of support type on feed conversion CH4 and CO2 conversions over synthesized samples as well as
equilibrium data are shown in Fig. 12. The thermodynamic data were obtained from the minimization of the Gibbs free energy. The feed conversion due to the high endothermicity of dry reforming enhanced with increasing reaction temperature. Due to the RWGS reaction the value of CO2 conversion is greater than CH4 conversion.
In this reaction H2 and CO2 are consumed and CO and H2O are produced (Rahemi et al., 2013b). Comparing the effect of the supports has shown the best performance of Ni/Al2O3 nanocatalyst at all temperatures. This is due to high specific surface area, small crystallite size, well Ni dispersion and particles size distribution. This value is nearly 93% at 850 C. Slightly high specific area of the Ni/Clinoptilolite nanocatalyst compared to Ni/CeO2 nanocatalyst, fine particles size and benefits of zeolites has resulted in better results for Ni/Clinoptilolite nanocatalyst. Among the supports, the
Al2O3 support showed the best performance. As mentioned in the introduction, the cost of mining and treatment of clinoptilolite is cheaper than the preparation of alumina. Although the feed conversion over Ni/Clinoptilolite nanocatalyst is slightly less than that of Ni/Al2O3 nanocatalyst, the CO2 and CH4 conversions at 850 C are acceptable.