Pore structure control in Ni/SiO2 catalysts with both macropores and mesopores

Ni/SiO2 catalysts with bimodal pore structure were prepared by the sol–gel method of silicon tetraethoxide and nickel nitrate in the presence of poly(ethylene oxide) (PEO) and urea. The presence of PEO was effective to induce phase separation during the sol–gel process, and through-macropores interconnected three-dimensionally were formed by fixing transitional structure of the phase separation. After gelation, the as-prepared wet gel was aged at 80 °C for decomposition of urea in order to increase pH of the solution within the gel. This pH increase led both the ripening of silica gel network through dissolution–reprecipitation and homogeneous deposition of nickel hydroxide. As a result, Ni could be dispersed highly in the silica network. In addition to the high dispersion of Ni, thus prepared Ni/SiO2 has typical bimodal pore structure with size-controllable macropores and mesopores. The bimodal porous Ni/SiO2 also had high thermal stability and showed steady catalytic activity in CO2-reforming of methane at 700 °C.