Effect of Reaction and Regeneration on the Production of Pyridine Bases through Glycerol and Ammonia Route

Abstract

The HZSM-22-At-acid and HZSM-5-At-acid catalysts were synthesized by alkaline-acid sequential treatment and the ZnO/HZSM-5-At-acid catalyst was synthesized by wet-impregnated method. Influence factors, including the types of reactors, impurities in glycerol and regeneration, were systematically investigated. The catalysts were characterized by XRD, TG, N2-physorption and NH3-TPD techniques. The catalytic evaluation showed that the total yield of pyridine bases in the series-connected two-stage reactors was significantly higher than that of the single reactor while the catalytic pair (HZSM-22-At-acid + ZnO/HZSM-5-At-acid) was employed in these reactors, respectively. It was found that the presence of methanol and sodium chloride in glycerol played a great negative effect on the total yield of pyridine bases. The coke was a key factor leading to the deactivation of catalyst. The catalytic activity was basically restored after the regeneration. The total yield of pyridine bases was increased up to 72% after the 6 th reaction, which was obviously higher than that of the similar reports. The characterization results demonstrated that the larger pore size and the declined concentration of acid site (particularly strong acid site) were main reasons for improving the catalytic activity.