Ni and/or Ni–Cu alloys supported over SiO2 catalysts synthesized via phyllosilicate structures for steam reforming of biomass tar reaction

Abstract

In this paper, we describe the synthesis of Ni/SiO₂ and Ni–Cu/SiO₂ catalysts derived from phyllosilicate structures (Ni/SiO_2P and Ni–Cu/SiO_2P, respectively) for steam reforming of biomass tar reaction. The steam reforming of biomass tar reaction was investigated with cellulose as a biomass model compound. The influence of steam-to-carbon ratio and reaction temperatures was also explored. Overall, the catalysts synthesized via phyllosilicate structures gave better catalytic performance than the catalysts prepared by the impregnation method. An optimum catalyst composition of 30Ni–5Cu/SiO_2P gave superior catalytic performance in terms of stability and activity compared to all other catalysts. At 600 °C, about 78% of biomass was converted to gaseous products over 30Ni–5Cu/SiO_2P, which is the highest among all the catalysts tested. Temperature-programmed reduction results indicate that the metal–support interaction of Ni/SiO_2P catalyst prepared via phyllosilicate structures is stronger due to the unique layered structure compared to that prepared by conventional impregnation (10Ni/SiO₂). The formation of a unique layered structure in Ni/SiO_2P and Ni–Cu/SiO_2P was also confirmed through TEM analysis. The surface elemental composition results obtained from XPS analysis show that the Cu/Ni surface molar ratio for Ni–Cu/SiO_2P catalysts is consistent with the actual molar ratio values obtained from SEM-EDX analysis. This result suggests that the bimetallic catalysts synthesized via the phyllosilicate structure route can yield uniformly distributed alloy species.