Effect of pore geometries on the catalytic properties of NiO–Al2O3 catalysts in CO2 reforming of methane

Mesoporous NiO–Al2O3 catalysts were prepared by an evaporation-induced self-assembly (EISA) method, during which the amount of HNO3 added in the precursor solution was varied. Characterization results indicated that the phase structure, component interaction and surface chemistry are fairly similar for all the samples, while the dispersion and textural properties, which are determined by the structure of the micelles and reaction rate of hydrolysis during the EISA process, changed significantly, thus leading to considerably different catalytic performance in CO2 reforming of methane (CRM). The well-known trend that carbon formation rate decreases with the decrease of Ni particle size was observed in the current NA-Hx samples, however, it is very interesting that the disordered slit-like pores endowed the NA-H32 sample with a better capability to inhibit carbon formation as it showed substantially fewer carbon deposits as compared with NA-H16 (ordered cylindrical pore), despite the fact that the Ni particles in these samples are of similar size. In summary, the excellent performance of the NA-H32 catalyst in comparison to other non-promoted NiO–Al2O3 catalysts holds promise for using this cost-effective system in practical CRM applications.