Hydrogen Production via Thermo-catalytic Methane Decomposition

Hydrogen production from the direct thermo-catalytic decomposition of methane is a promising alternative for clean fuel production because it produces pure hydrogen without any COx emissions. However, thermal decomposition of methane can hardly be of any practical and empirical interest in the industry unless highly efficient and effective catalyst, in terms of both catalytic activity and operational lifetime have been developed. In this work, the effect of introducing palladium as promoter onto nickel supported on alumina catalysts have been investigated by both co-precipitation and incipient wetness impregnation method. The calcined catalysts were characterized to determine their morphologies and physico-chemical properties by the application of Scanning Electron Microscopy (SEM) imaging, Energy Dispersive X-ray Spectroscopy (EDX) analysis, Brunauer-Emmett-Teller method, Temperature Programmed Reduction (TPR) and Thermogravimetric Analysis (TGA). In addition, experimental work is conducted at 873 K, 973 K and 1073 K to evaluate the performance of the catalysts for methane cracking process. The morphology studies suggested that the catalysts which were prepared by co-precipitation method exhibit homogenous morphology, higher surface area, have uniform nickel and palladium dispersion while the catalysts which were wet impregnated has higher thermal stability. This characteristics are significant to avoid deactivation of catalyst due to sintering and carbon deposition during methane cracking process. The experimental studies suggested that introducing palladium as promoter onto Ni/Al2O3 catalyst has a significant effect on the catalytic activity, operational lifetime and thermal stability of the catalysts. The Ni-Pd/Al2O3 catalyst which was synthesized by wet impregnation method gave the highest initial methane conversion which can be explained in term of the morphology of the catalyst in which accumulation of Ni and Pd particles on the active site of the catalyst promotes higher initial catalytic activity. However, this catalyst deactivated at a faster rate due to carbon deposition on the active sites of catalysts. On the other hand, the homogeneous morphology and higher surface area of the Ni-Pd/Al2O3 catalyst which was prepared by co-precipitation method enables longer operational lifetime and higher thermal stability to be achieved.