Kinetic Study of Optimum Ni-Al-Zn Catalyst in the Steam Methane Reforming Reaction

In this study, steam methane reforming was investigated by using Ni-Al-Zn catalyst. This process carried out at 750-900 °C in the industrial plants. From the economical and operational point of view, the reduction of operational temperature is important. Therefore, the Ni-Al-Zn catalyst was studied to decrease the operational temperature. This catalyst was synthesized by coprecipitation method. The results of XRD, ICP, and BET revealed that catalyst were appropriately synthesized. Then, this catalyst was used in the steam methane reforming process and 15% nickel was obtained as optimum value. The performance of optimum catalyst at 650 °C was similar to industrial catalyst at 750 °C, so that the methane conversion was about 75 %. This catalyst showed high carbon resistance at temperatures above 600 °C. Kinetic study of optimum catalyst was performed. Moreover, the activation energy for reaction of methane to CO and H2, water gas shift and methane to CO2 and H2 were 219.4 kJ/mol, 71.90 kJ/mol, and 221.04 kJ/mol, respectively. The results of kinetic experiments on the synthesized catalyst showed that the activation energy for the first and third reactions of reforming (hydrogen production via methane and steam) was less than the activation energy on the industrial catalyst which reveals higher activity of the synthesized catalyst. Furthermore, the adsorption parameters in the kinetics equations were obtained and thermodynamically verified.