文献类型：期刊文献

英文题名：Monolithic Ts-1 Prepared with Nitrogen-Doped Carbon Nanotubes as Carriers and the Structure-Activity Relationships in Propylene Epoxidation

作者：Ji, Shuang[1]; Cao, Gui-Ping[1]; Lv, Hui[1]; Gao, Peng[1]; Wang, Chun-Xue[1]

机构：[1] UNILAB, State Key Laboratory of Chemical Engineering, East China University of Science and Technology, Shanghai, 200237, China

年份：2024

外文期刊名：SSRN

收录：EI(收录号：20240037215)

语种：英文

外文关键词：Binding energy - Carbon nanotubes - Chemical vapor deposition - Doping (additives) - Foams - Hydrogen bonds - Nitrogen oxides - Nucleation - Pyridine - Synthesis (chemical)

摘要：TS-1 is a mild and efficient catalyst for olefin epoxidation reactions. In order to improve the catalytic performance, a monolithic TS-1 was successfully synthesized by dry gel conversion using nitrogen-doped carbon nanotubes grown on nickel foam surface as the carrier in an ammonia gas phase environment. The nitrogen atoms in the carrier could form hydrogen bonds with the silicon species in the raw material, providing nucleation sites for crystallization, resulting in uniform particle dispersion and avoiding the detachment of TS-1. The binding energy sequence of the four nitrogen atoms with the silicon species was: nitrogen oxides > pyrrole nitrogen > pyridine nitrogen > graphite nitrogen. Nitrogen-doped carbon nanotubes grown at 550 °C by chemical vapor deposition owned the highest content of pyridine nitrogen (1.28 at %) and nitrogen oxide (0.40 at %), which provided the most nucleation sites for TS-1. Compared with powder TS-1 obtained by hydrothermal method, the crystallization time of the monolithic TS-1 was shortened from 72 h to 18 h. There was an optimal amount of ammonia, if the amount of ammonia was little, the molecules in the solid gel were difficult to move, and crystallization was difficult to occur, but excessive ammonia reduced the degree of supersaturation, resulting in a transformation to hydrothermal crystallization. ? 2024, The Authors. All rights reserved.