Study Of Structure-Property Relationship Of The Catalysts For Synthesis Of Pyridine Bases

With the increase of needs of society and the rich of domestic raw materials, pyridines bases have an irreplaceable role in pesticide, medicine field. Domestic pyridine market has tremendous potentiality and economic value and about 65% of the world's pyridine bases is in China. But byproducts of pyridine are very complicated, which increases the difficulty of separation and purification of products and energy consumption. How to improve the selectivity of pyridine is one of hot issues in chemical engineering.The study analyzed the catalytic performance of different catalysts on aldehydes-ammonia condensation and optimized the process conditions. By comparison, HZSM-5(150) was chosen for the modified zeolite. Optimization of process conditions were reaction temperature 450?, formaldehyde/acetaldehyde=2/3, aldehyde/NH3=1/2, GHSV= 2000h-1,time on stream= 2-3h.The conditions of HZSM-5 modified by TEOS included the CLD agents, percentage ratio, modification time and deposition number. The result indicated that the suitable TEOS percentage ratio and modification time were 5% and 8h for one cycle and the selectivity of pyridine/3-MP increased from 2.38 to 2.96. With the increase of deposition level of TEOS, the selectivity of pyridine was obviously promoted. The modified HZSM-5 was characterized by XRD, BET, TPD, SEM and FT-IR. As a result, most of TEOS loaded on the out surface of catalyst, the acid site of out surface were covered and pore size reduced.HZ5-5 and HZSM-5 were modified by 1 wt% Zn, respectively. The experiment studied the catalytic performance of two catalysts on aldehydes-ammonia condensation. The selectivity of pyridine/3-MP were 3.13 and 2.45, increasing 31.5% and 2.9%, respectively. By XRD, XPS, BET, TPD and FT-IR, the result indicated that ZnO was the main form of zinc element distributed on molecular sieve surface. ZnO was easy to react with H+(ZnO+H+?ZnOH+) and ZnOH+ could decrease the strong and weak acid site number.The experiment designed process of aldehydes-ammonia condensation, including reactor section, extraction section, debenzolization section and rectifying section. According to distribution of products, simulation used Aspen Plus.