【摘要】 以稻壳活性炭作为碳源,硝酸镍为金属前驱体,采用浸渍法结合碳热还原和催化石墨化的方法制备了具有良好香草醛加氢脱氧催化性能的稻壳基活性炭负载镍催化剂。在催化剂的制备过程中,稻壳活性炭作为金属前驱体的还原剂,金属镍作为稻壳活性炭催化石墨化的催化剂。以生物油模型化合物香草醛加氢脱氧制备4-甲基愈创木酚为探针反应,考察制得催化剂的加氢脱氧反应性能。采用X射线衍射、高分辨透射电镜、拉曼光谱仪、氮气吸附仪等手段对催化剂中Ni的价态、粒径和分散情况,石墨化程度、比表面积、孔径等进行表征。结果表明,催化剂的结构和其催化性能存在密切联系。随着碳热还原温度的升高,催化剂的催化活性出现了先降低而后提高的趋势。这是由于较高的碳热还原温度引起镍纳米粒子的聚集和长大,不利于其催化性能;同时较高的碳热还原温度促使催化剂石墨化程度的提高,对其催化性能起到促进作用。更多还原

【Abstract】 Ni-rice husk carbon catalysts with Ni loadings from 2 to 8 w t% were prepared by impregnating rice husk activated carbon with Ni( NO3)2·6 H2 O solutions,followed by carbothermal reduction at temperatures from 500 to 950 ℃. The valance,particle size and dispersion of nickel nanoparticles on the carbon,the graphitization extent of the carbon,and the pore structure of the catalysts were investigated by XRD,TEM,Raman spectroscopy and nitrogen adsorption. The activity and selectivity of the catalysts for the hydrodeoxygenation of vanillin to 2-methoxy-4-methylphenol were evaluated. Results indicate that by increasing the carbothermal reduction temperature,the specific surface area and micropore volume decrease,mesopore volume and average pore size increase,nickel particle size increases and the( 002) peak of carbon appears and becomes sharp above 900 ℃. The selectivity of all catalysts investigated is 100%. The catalytic activity is closely related to the Ni content and its dispersion on the carbon. A high Ni loading of over 6 w t% and reduction at temperatures higher than 800 ℃ lead to aggregation of the nickel nanoparticles,which lowers the catalytic activity.更多还原