Synthesis of Pyrazines from Biomass-Derived Vicinal Diols Using Ammonia over Heterogeneous Pt/CeO2/Al2O3 Catalysts

Abstract

One-pot amination coupling of vicinal diols toward the synthesis of pyrazines provides an efficient and economically viable route to access N-heterocycles from biomass, yet the current methodology relies on a fragile homogeneous catalyst system, which limits the sustainability of the chemistry. In this work, we developed a highly efficient heterogeneous catalyst 0.8Pt/13CeO₂/Al₂O₃ which afforded diverse substituted pyrazines from readily available vicinal diols and ammonia with a yield up to 94% under mild reaction conditions and could be reused at least 6 times without obvious activity decay. Compared to the Pt/Al₂O₃ catalyst, the 0.8Pt/13CeO₂/Al₂O₃ catalyst exhibited a 30-fold faster conversion rate of diols and an increased pyrazine selectivity from 48% to 79%. Characterizations revealed that doped CeO₂ improved the dispersion of Pt, increased the electron density on the Pt sites, optimized the acid/basic property of the catalyst, and enhanced the adsorption strength and dehydrogenation ability of diols. All these features contributed to the increased activity and selectivity.