Design and Optimization of Carbon-Based Bimetallic Catalysts for Catalytic Cracking of Tar Model Compounds.

Biomass tar from pyrolysis restricts the practical engineering application of biomass gasification. Carbon-based bimetallic Ni-based catalysts modified by Cu and Co promoters were synthesized to boost catalytic performance for toluene cracking. Physicochemical characterizations under two preparation atmospheres reveal that Ni-Cu and Ni-Co alloys raise surface Ni° content and inhibit metal oxidation. Uniformly dispersed tiny metal particles also increase hydrogen concentration in product gas. Experimental results show that Ni4-Cu1-H delivers excellent low-temperature activity at 600°C, while Ni4-Co1-H achieves a maximum hydrogen selectivity of 75% owing to smaller metal grains. Stability tests confirm Ni4-Cu1-H maintains the best activity after 300 min reaction. Comparative characterizations of fresh and spent catalysts clarify the anti-deactivation mechanism of bimetallic catalysts: they suppress amorphous carbon graphitization and alter carbon deposition forms, thus slowing catalyst deactivation.