Synthesis of pyridine bases from ethanol, methanol and ammonia over micro-mesoporous Zn–OH/HZSM-5 catalyst

Micro-mesoporous Zn–OH/HZSM-5 catalysts were prepared by alkaline treatment and Zn modification of HZSM-5 zeolite for the synthesis of pyridine bases from ethanol, methanol and ammonia through a fixed bed reactor. It has been discovered that a large number of bigger micropores and mesopores were produced because of the disappearance of the neighboring walls of two bigger micropores and crossing walls of three micropores. At the same time, the strong acid sites of HZSM-5 zeolites became weaker and fewer due to desilication and dealumination. It was believed that the micro-mesoporous structure of the catalysts, the amount and strength of the weak and medium acid sites, as well as suitable ethanol/methanol/ammonia ratio were the key factors that affected the formation of pyridine bases from alcohol and ammonia. The highest yield and selectivity of pyridine bases were 50.27% and 59.45% over Zn-5-OH/HZ5 catalyst at 410 °C, WHSV = 2.0 h−1 and C2H5OH/CH3OH/NH3 = 2/1/3 (mol) after amination, dehydrogenation, cycloaddition and deamination from ethanol, methanol and ammonia.