Synthesis And Structure Control Of Composite Materials Of Carbon Nanofiber Honeycomb And Monoliths As Catalyst Material

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.