Furans are important scaffolds with applications in pharmaceuticals, polymers synthesis and biofuels. The direct production of new types of furans from glucose is therefore significant but remains a great challenge. Herein, we report a facile strategy to produce acetylfurans directly from glucose over MoCs-SiO 2 , with an increase in yield from 35.8 % to 81.4 % compared with pristine Mo-SiO 2 due to the facilitated C−C bond cleavage of glucose. The incorporation of Cs improved the dispersion of Mo species, induced the formation of partially reduced Mo, increased the Lewis acidity and glucose adsorption of the catalyst, and thus shifting the reaction selectivity from C−C coupling to cleavage. Kinetic studies further demonstrated the positive contribution of Cs as a promoter in lowering the activation energy of C−C bond cleavage. This study provides a promising strategy to broaden the range of furanic compounds derived from glucose for product-oriented biorefineries.
Jie Sun,Qiuxia Cai,Yan Wan,Shaolong Wan,Li Wang,Jingdong Lin,Donghai Mei,Yong Wang
The promotional effects of a cesium promoter on higher alcohol (C2+OH) synthesis from syngas over Cs2O-Cu/ZnO/Al2O3 catalysts were investigated using a combined experimental and density functional theory (DFT) calculation method. In the presence of a cesium promoter, the C2+OH productivity increases from 77.1 to 157.3 g kgcat–1 h–1 at 583 K due to the enhancement of the initial C–C bond formation. A detailed analysis of chain growth probabilities (CGPs) confirms that initial C–C bond formation is the rate-determining step in the temperature range of 543–583 K. Addition of a cesium promoter significantly increases the productivities of 2-methyl-1-propanol, while the CGP values (C3* to 2-methyl-C3*) are almost unaffected. With the assistance of a cesium promoter, the CGPs of the initial C–C bond formation step (C1* to C2*) increase from 0.13 to 0.25 at 583 K. DFT calculations indicate that the initial C–C bond formation during syngas synthesis over the ZnCu(211) model surface is mainly due to the HCO + HCO coupling. In the presence of Cs2O, the stabilities of key intermediates such as HCO and H2CO are enhanced, which facilitates both HCO + HCO and HCO + H2CO coupling steps with lower activation barriers. In addition, Bader charge analysis suggests that the presence of cesium ions could facilitate nucleophilic coupling between HCO and H2CO for the initial C–C bond formation.
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