【作者】 牛鹏星；

【导师】 乔文明；

【作者基本信息】 华东理工大学 ， 材料化学工程， 2011， 硕士

【摘要】 蜂窝状堇青石作为催化剂载体,既具有高机械强度、低的热膨胀系数、低气压压降,又有很多优良的物理化学性能。纳米碳纤维作为催化剂或催化剂载体具有结构单一,表面纯净,耐酸耐碱,以及石墨层与表面负载金属之间的相互作用等优良的物理化学特性。然而,蜂窝状堇青石比表面积较低,不利于担载催化剂；纳米碳纤维粉体结构作为催化剂载体应用于气相反应器时,会带来流体阻力大、易堵塞反应器等问题。本论文针对蜂窝状堇青石和纳米碳纤维作为催化剂载体存在的不足,展开了纳米碳纤维/蜂窝状堇青石复合载体的制备及结构控制研究。首先采用溶胶-凝胶法制备涂覆在蜂窝状堇青石表面上的氧化铝涂层；然后采用化学气相沉积方法,在氧化铝涂层上生长纳米碳纤维。研究结果表明：1)氧化铝溶胶中拟薄水铝石固含量为15%,浓硝酸为22.5%,制得适宜涂覆在蜂窝状堇青石上的氧化铝溶胶；2)采用分步干燥法,制备出均匀、完整和结合强度高的氧化铝涂层；3)通过优化CNF生长条件,制备的纳米碳纤维直径均一,分布均匀,复合材料机械强度高,结合牢固；4)通过向Ni基催化剂中加Cu,来解决Ni催化剂失活的问题；5)螺旋状纳米碳纤维是Ni-Cu催化剂在载体表面扩散或者聚合形成一定直径的大颗粒催化剂,生长出直径100nm左右的螺旋状纳米碳纤维；6)纳米碳纤维/蜂窝状堇青石为催化剂载体,V205为催化剂,用于烟气脱硝,280℃,空速为6000h-1,转化率达到60%。更多还原

【Abstract】 Honeycomb monolith exhibits a lot of advantages, such as high mechanical resistance, good refractory properties, high thermal shock resistance and good compatibility with the catalyst washcoat. In addition, the straight parallel channels provide very low pressure drop provide low pressure drop.Carbon nanofiber(CNF) is a promising candidate as for catalyst support. The main advantages of CNF are the high purity preventing poisoning and side reactions, the chemical stability in acidic and basic media and specific metal-support interactions, which offers the possibility to modify the catalyst performance with respect to other supports. However, CNF in powder form has some drawbacks, such as high pressure drop for gas phase operation.In this account, CNF/honeycomb monolith composite with high specific surface area and low pressure drop was prepared for catalyst support of selective catalytic reduction (SCR) of NO in low temperature. The alumina washcoat was deposited on honeycomb monolith via sol-gel method. And CNF was gown on the alumina washcoat layer by chemical vapor deposition (CVD). In addition, the performance of CNF/honeycomb monolith supporting V2O5 for SCR of NO was investigated.The main results are given as follows.1) The optimized alumina sol for washcoat was synthesized with 15wt% seudoboehmite and 22.5% nitric acid.2) The smooth and uniform of washcoat with high mechanical strength was prepared by step drying method.3) CNF with uniform diameter was homogeneously gown on the washcoat by CVD, and the complete adhesion of the CNF layer and higher mechanical strength than the original honeycomb monolith was obtained.4) Ni-based catalyst with high stability and resisting carbon deposition for the CNF growth was developed by adding Cu to the active component of the catalyst.5) The appearance of helical CNF was attributed to a coarsening of the small catalyst particles, which occured either through surface diffusion or particle coalescence to grow to a certain size to initiate the growth of helical CNF with a diameter of 100nm.6) V2O5 catalyst supported on CNF/honeycomb monolith was prepared for SCR of NO. Its best NO conversion reached 60% at 280℃and 6000 h-1.更多还原