Due to the limitations of powdered catalysts in continuous catalytic system, such as high pressure drop, easy blocking and the loss of active components, monolithic carbonaceous composite catalyst with high voidage was employed for phenol degradation in fixed bed reactor. Firstly, monolithic NCNTs/PSSF microfibrous composite catalyst was synthesized by chemical vapor deposition (CVD) method using melamine as the sole carbon and nitrogen source, and effects of temperature, flow rate of carrier gas and the amount of melamine on the morphology and structure of catalyst were investigated. Then catalyst synthesized under optimized conditions was applied for catalytic wet peroxide oxidation of phenol in a fixed bed reactor. Characterization results indicated that the catalyst exhibited a three-dimensional network structure and stainless steel fibers were wrapped with NCNTs. The quality and yield of NCNTs increased with the increase of temperature, while morphology transition could be observed at 1 000 ℃. With the increase of carrier gas flow rate, the yield and quality of NCNTs decreased while the specific surface areas and total pore volume increased.With the increase of the amount of melamine, the yield of NCNTs increased and the quality remained nearly unchanged. The specific surface areas of catalyst synthesized under optimized conditions was 14.50 m2/g, about 45 times larger than that of the bare PSSF support, and TEM images showed that NCNTs with a nitrogen-doping level about 4% exhibited distinct inter-linked corrugated morphology and highly wrinkled nanotube walls. CWPO of phenol under conditions of 2 cm of catalyst bed height (contained only about 0.5 g NCNTs), 2 mL/min of feed flow rate and temperature of 80 ℃ showed that 99% of H2O2conversion could be achieved, and phenol and TOC conversions could reach 80% and 45%, respectively, after 9 h continuous reaction. Moreover, only few Fe3+leaching concentration (1.5 mg/L) was detected. Long term catalytic tests further indicated that high phenol conversion over 80% could still be achieved by using the catalyst over 100 h, and Fe3+leaching concentration was detected lower than 5 mg/L.
