Highly dispersed Cu nanoparticles as an efficient catalyst for the synthesis of the biofuel 2-methylfuran

Abstract

Cu/SiO₂ catalysts were synthesized by different methods, which greatly influenced their texture and the catalytic performance. The AE-Cu/SiO₂ catalyst was prepared via the ammonia evaporation method and showed a 95.5% yield for 2-methylfuran (a promising fuel additive) because of the cooperative effects of surface Cu⁰, Cu⁺ species and acid sites, which respectively stemmed from the reduction of highly dispersed CuO species, copper species that fiercely interacted with the support SiO₂, and the special structure. The ammonia evaporation method favored the formation of a copper phyllosilicate phase with a lamellar structure, which could provide a large number of Cu nanoparticles and acid sites and further improve the activity and selectivity. Crucially, the stability of the AE-Cu/SiO₂ catalyst (>210 h) was also significantly improved due to the enhanced copper–silicon interactions, which could immobilize copper particles and resist the fast transmigration (aggregation and loss) of copper particles in the thermal treatment process. In contrast, the CP-Cu/SiO₂ catalyst was synthesized via the conventional precipitation method and presented poor activity and stability toward 2-methylfuran because of large copper particles, severe aggregation and a loss of copper species during reaction. Compared with the conventional CP-Cu/SiO₂ catalyst, the use of the AE-Cu/SiO₂ catalyst in the synthesis of the biofuel 2-methylfuran could not only improve the yield of the desired product, but also decrease by at least 20 °C the reaction temperature which is propitious for prolonging the lifetime of the Cu/SiO₂ catalyst.