Pore diameters of Ni/ZrO2 catalysts affect properties of the coke in steam reforming of acetic acid

Pore structures of support affect not only the dispersion of metals species, but also the catalytic stabilities and the properties of the generated coke in steam reforming reaction of acetic acid. This has been demonstrated in this study with Ni/ZrO₂ catalysts of varied pore diameters. The results showed that the Ni/ZrO₂ catalyst with the support calcined at 700 °C had the largest diameter, which facilitated the entering of nickel species into the pores, suppressing the migration and agglomerate in reduction of the catalysts. Although the catalysts with the varied pore diameters showed little impacts on the catalytic performances, the properties of the coke varied substantially. The catalyst with the large pore diameter favored the growth of the crystal carbon in the coke to a bigger size and was more tolerant to coke accumulation while maintained the catalytic stability. In addition, thermal stability, resistivity to oxidation, aromaticity, functionalities and the morphologies of the coke (i.e. carbon nanofibers, carbon nanotubes and bamboo-like structure) were all connected with the porous structures of the Ni/ZrO₂ catalysts.