Bimetallic oxide catalysis meets silanol-enhanced synergy: A winning combination for efficient CO2 fixation by cycloaddition with styrene oxide

The bimetallic oxide dispersed on silanol rich SBA-15-OH was designed for the synthesis of cyclic carbonates from epoxides and CO2. The SBA-15-OH was synthesized via desilication and active metals were loaded by sol-gel method. Pure Sn-Ni oxide with a low surface area and lesser activity was modified by dispersing it on a high surface area SBA-15-OH. The different characterization techniques such as XRD, N2-sorption, CO2 and NH3-TPD, H2-TPR, SEM-EDX, TEM and XPS confirmed that the surface silanol group acts as anchoring site for the enhanced metal oxide-support interaction. Supported Sn-Ni oxide exhibited 16-fold better activity than pure Sn-Ni oxide, due to improved dispersion, which enhances the accessibility of reactants to the catalytic sites. Under the optimized reaction conditions 10Sn5Ni/SBA-15-OH gave 92.9 % styrene oxide conversion and 84.3 % selectivity for styrene carbonate. The catalyst is recyclable and the flexibility of the catalyst is tested for different epoxides with CO2.