The preparation of a good catalyst starts with the selection of the appropriate support, which includes good textural properties such as surface area, porosity, and pore volume. The catalyst’s support plays an important role in the activity and selectivity of the catalyst. The surface area, on one hand, permits the loading and dispersion of the active species, while the support’s pore size controls the diffusion of reactant molecules to reach the active species located within the internal areas of the pores. Therefore, using the physisorption technique to elucidate the textural properties of the support must be the first and most important task. The chemisorption techniques—normally called TPX techniques—are widely used to study the role of the support in stabilizing and dispersing the active species under reaction conditions of high temperature and pressure, which could easily sinter the active particles and, thus, cause rapid deactivation of the catalyst.
The Sabatier reaction was carried out in this study by reducing CO₂ with H₂ to produce CH₄ using Ni-supported catalysts. Two catalysts were used, each having about 5% Ni and supported on materials with different surface areas. Slowly increasing the reactor temperature (about 2°C/min) from ambient, and online monitoring the appearance of the products with a mass spectrometer, permits following step by step the evolution of the reaction and the appearance of the products as a function of the increasing temperature.
The results of this study indicated that the higher surface area catalyst produced a larger amount of CH₄, exhibited lower sintering of the active species, and, thus, allowed for the online monitoring of the reaction evolution to elucidate step by step the appearance of the products as a function of the increasing temperature.
