Response Surface Methodology for Ni-Zeolite Catalyst Optimization in Syngas Production.

This work addresses the problem of converting waste methane, a significant greenhouse gas, using customized nickel-zeolite catalysts to produce profitable syngas. The investigation employs 5 wt % of Ni on various zeolite supports with Si/Al ratios ranging from 13 to 25. Comprehensive characterization methods, including temperature-programmed reduction, N adsorption-desorption, and X-ray diffraction, were used to identify critical structural characteristics that greatly impact the catalyst's performance. The study indicates that the reducibility and basicity of the catalyst, the type of zeolite support, and the kind of carbon deposits formed during the reaction at 800 °C all influence the efficiency of methane conversion to syngas. The best catalyst was found to be 5Ni-Z3, which at 800 °C produced high conversion rates of carbon dioxide (60%) and methane (50%). Lastly, the response surface methodology, in conjunction with numerical simulation, was used to determine the best operating settings for maximizing syngas production with the 5Ni-Z3 catalyst. Reaction temperature, space velocity, and the methane-to-carbon dioxide feed ratio were considered in this analysis. With a methane conversion rate exceeding 92%, a carbon dioxide conversion rate exceeding 90%, and a hydrogen-to-carbon monoxide ratio of 1.00, the catalyst produced experimental results very similar to the SRM predictions when the reaction was conducted at conditions close to the predicted values [temperature around 845 °C, space velocity around 22,000 mL/(h·gcat), and feed ratio close to 0.94]. The effectiveness of the identified operating conditions for the dry reforming process is validated by the near alignment of expected and experimental outcomes.