陶金泉 1贾亦静 2白天瑜 2黄文斌 2崔岩 3周亚松 2魏强2
作者信息
- 1. 中国石油大学(北京),北京 102206||中国石油天然气股份有限公司石油化工研究院,北京 102206
- 2. 中国石油大学(北京),北京 102206
- 3. 中国石油天然气股份有限公司石油化工研究院,北京 102206
- 折叠
摘要
Abstract
Pyridine and its derivatives,collectively referred to as pyridine bases,are widely used in industries such as pesticides and pharmaceuticals,serving as crucial intermediates in the chemical industry.In recent years,with the development of the pesticide and pharmaceutical industries,the demand for pyridine bases has rapidly increased.The Chichibabin condensation reaction is the most commonly route for industrial production of pyridine bases.Currently,the most used ZSM-5 zeolite catalyst is limited by the instability of its silicon-aluminum framework structure,resulting in a short active reaction cycle(5 h).To address this limitation,this study selected the thermally stable and hydrothermally stable Silicalite-1 zeolite.Polyvinylpyrrolidone(PVP)was employed as a colloidal dispersant and Fe was introduced into the MFI framework through in situ modification during the hydrothermal synthesis of zeolite.The influence of PVP dosage,template agent dosage,and other crystallization conditions on the crystallinity,pore structure,and acidity of Silicalite-1 zeolite products was investigated using XRD,SEM,TG,and N2 adsorption-desorption measurement.The acidity of Fe-modified Silicalite-1 zeolites was characterized using NH3-TPD,Py-IR,FT-IR,and XPS.These results indicated that the introduction of seed crystals effectively reduced the particle size of the zeolite to about 200 nm.Fe-modified Silicalite-1 displayed a disk-like morphology with excellent crystal dispersion.The highest relative crystallinity of the zeolite reached 103％with 15％seed crystal input and 3.75％PVP addition.The Fe-modified Silicalite-1 possessed a significantly enhanced abundance of both Lewis(L)and Brønsted(B)acid sites,resulting in an increase in the initial activity from 66％to 85％for the pyridine bases synthesis through the Chichibabin condensation.Compared to ZSM-5,Fe-modified Silicalite-1 exhibited superior catalytic stability,maintaining the total carbon conversion and pyridine bases yield above 66％and 40％,respectively,over a 15 h reaction period.Furthermore,the strategy proposed in this study,employing polyvinylpyrrolidone as a colloidal stabilizer to modify Silicalite-1 zeolite,could significantly broadened the application prospects of weakly acidic pure silica zeolites in the field of acid catalysis.This approach has demonstrated significant scientific value and industrial potential.关键词
Silicalite-1分子筛/原位改性/水热法/催化剂/醛氨缩合反应Key words
Silicalite-1 zeolites/in-situ modification method/hydrothermal method/catalyst/Chichibabin condensation reaction分类
化学化工
