What is the effect of carrier surface alkalinity on catalyst performance?

The Al₂O₃ carrier, as the backbone of the active component Ni, not only plays a role in supporting and dispersing the Ni grains, but also has a significant chemical role. The increase of carrier surface alkalinity will enhance the adsorption of water vapor and CO₂ on the catalyst surface, while the increase of surface microscopic water content (i.e., H₂O/CH₄) will inhibit the occurrence of the carbon accumulation reaction, and the presence of a large amount of CO₂ on the surface can change the equilibrium of the carbon reaction, so that the carbon accumulated on the catalyst surface can be removed by CO₂ in time. The relationship between the modification of the carrier surface alkalinity by additives and its anti-carbon accumulation performance, H₂O-TPD and CO₂-TPD, showed that the addition of alkaline additives did increase the adsorption of H₂O and CO₂ on the surface of the catalysts under the condition of low H₂O/CH₄, and at the same time, the anti-carbon accumulation performance of the catalysts could be improved. The carbon accumulation behavior of Ni catalysts loaded with different carriers Al₂, TiO₂, and ZrO₂ in the CO₂/CH₄ reforming reaction was investigated, and it was found that the amount of carbon accumulated on the catalysts was in a cis-variable relationship with the Lewis acid strength of the carriers.