A series of Cu/SBA-15 catalysts with different Cu loadings are prepared by the ammonia evaporation method for the liquid-phase hydrogenation of furfural (FF) to furfuryl alcohol (FA). The results show that the supported Cu loading influences the structure and catalytic activity during FF hydrogenation. The 20Cu/SBA-15 catalyst shows the optimum performance with 99.3 % FF conversion, 99.0 % selectivity to FA, nearly pure FA product, and a turnover frequency reaching up to 81.7h −1 . The effect of Cu loading can be related to Cu dispersion and the interaction between the metal and support, which further promotes the surface Cu + /Cu 0 ratio. Additionally, the correlation of FF conversion with Cu + /Cu 0 ratio confirms that the excellent performance of 20Cu/SBA-15 is mainly derived from the synergy of Cu + and Cu 0 species, although the range of performance is not large. Finally, the optimal reaction conditions are screened using a reaction temperature of 150 °C, a reaction pressure of 4 MPa, a catalyst dosage of 0.1 g, and a reaction time of 60 min. The present study confirms that the Cu loading has a significant effect on the structure of Cu/SBA-15 and nearly pure objective FF product can be feasibly obtained with an appropriate Cu support in the synthesis of FA from FF hydrogenation.
Catalytic oxidation of carbon monoxide (CO) by Cu/Al 2 O 3 has garnered increasing interest in recent years due to its promising application prospects. Numerous investigations conducted on the Cu/Al 2 O 3 system, but its catalytic performance for CO oxidation is still not as promising as that of precious metal catalysts. Increasing the loading amount of the active Cu on Al 2 O 3 surface is a feasible method for improving its activity. However, with the increase of Cu loading, the agglomeration and enlargement of Cu particles is inevitable, which reduces the active Cu amount. Therefore, the utilization rate of Cu atoms is not high and the catalytic performance often can not further rise. Enhancing active Cu loading amount as high as possible is a prerequisite to further enlarge the activity of Cu/Al 2 O 3 catalyst. Herein, self-synthesized Al 2 O 3 nanofibers (Al 2 O 3 -nf) with high specific surface area and abundant penta-coordinated aluminum (Al V ) are used as the support to maximize the Cu loading amount by chemical vapor deposition (CVD). And commercially available α-Al 2 O 3 is used for comparative experiment. The high specific surface area could make Cu high dispersion on Al 2 O 3 , even at 20 wt% Cu loads, which is beneficial to high concentration load of active Cu. The catalytic activity of Cu/Al 2 O 3 -nf-CVD gradually increases with the increase of Cu loading from 2 wt% to 20 wt%, exhibiting a clear linear correlation with the surface content of Cu 0 on the catalyst. Meanwhile, this result confirms that Cu 0 plays a crucial role in CO oxidation of Cu/Al 2 O 3 . However, commercial α-Al 2 O 3 reaches its highest activity when the Cu load is 5%, and then its activity begins to decrease due to the agglomeration of particles. Moreover, Cu/Al 2 O 3 -nf-CVD also exhibits remarkable thermal stability for CO oxidation. This work highlights a new strategy to synthesis of high Cu loading amount, high activity and thermostable Cu/Al 2 O 3 catalyst for low-temperature oxidation of CO.
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