微波协同氧化锆@碳纳米管强化果糖制5-羟甲基糠醛

糖类催化转化是生产生物质基燃料和高附加值化学品的重要途径，而微波能量的使用可使这一过程更具商业可行性。本文探究了微波辐射下微波响应型催化剂碳纳米管负载氧化锆［ZrO₂/MWCNTs(C)］催化的果糖高效分解制5-羟甲基糠醛（5-HMF）过程。首先，采用水热法制备了性能优异的氧化锆@碳纳米管催化剂，并对其进行表征；进一步考察了催化剂用量、果糖浓度、反应温度和反应时间对反应产物5-HMF收率的影响，并通过调节各组分在反应过程中的实际含量，探究微波强化的作用机理。研究结果表明在相对温和的条件下（120℃、常压），微波辐射下的5-HMF收率（约74%）远高于常规加热条件下的5-HMF收率（约31%）；采用最佳ZrO₂60/CNTs用量（ZrO₂质量分数约为60%），微波场中，140℃常压条件下反应10min，可以实现约98%的果糖转化率和92%的5-HMF收率。通过探究载体吸波性能与活性位点催化性能之间的耦合匹配关系，揭示了微波协同催化过程强化机理归因于具有强吸波性能碳质载体的选择性加热和活性位点ZrO₂之间的协同耦合作用。

Conversion of fructose to 5-hydroxymethylfurfural catalyzed by microwave-assisted zirconia@carbon nanotubes

Catalytic conversion of saccharides is a promising way for the production of biomass-based fuel and high value-added chemical, and the utilization of microwave energy can make this process more commercially viable. In this paper, the efficient decomposition for fructose to 5-hydroxymethylfurfural (5-HMF) catalyzed over carbon nanotube-supported zirconia ZrO₂/MWCNTs(C)] as a microwave response catalyst under microwave irradiation was investigated. Firstly, hydrothermal synthesis method was used to synthetize ZrO₂@MWCNTs(C) catalysts with high performance and then, they were characterized. Moreover, the effects of catalyst dosage, fructose concentration, reaction temperature and reaction time for the yield of 5-HMF were further investigated and lastly, by adjusting the participation of each component for composite catalyst during reaction, the microwave strengthening mechanism was revealed. Under a mild MW condition (at 120℃, atmospheric pressure), high 5-HMF yield about 74% after 10min reaction time was achieved which was significantly higher than that obtained under the conventional heating about 31%. With the optimum dosage of ZrO₂60/CNTs (50%), about 98% fructose conversion and about 92% 5-HMF yield could be achieved with microwave irradiation at 140℃ and atmospheric pressure for 10min. By exploring the coupling matching relation between the absorption performance of the supporting and the catalytic performance of the active site, the strengthening mechanism of the microwave synergistic catalytic process was revealed, which may be attributed to the combination of selective heating for carbon supporting and the active site of zirconia.