Continuously Synthesis Of Morpholine From Diethylene Glycol In Vapor Phase And The Related Catalyst Characterization

Morpholine, its chemical name is1-Oxa-4-azacyclohexane, is an important intermediate of fine chemicals because of its special structural characteristics of oxygen heterocyclic, and has been widely used for production of rubber assistants, medicines, paints, dyes and so on. Nowadays, the process for producing morpholine through catalytic aminolysis of diethylene glycol is widely used. This process has many advantages, such as raw materials readily available, low equipment requirements and less pollution. The major problems of the process are the low activity of the catalyst and the low yields of the products.In this paper, self-built high-pressure fixed bed reactor was the major equipment to evaluate the activity of catalyst and explore the conditions of synthesis of morpholine. Compared to the process for producing morpholine intermittently with the autoclave in liquid phase, continuously synthesis of morpholine in vapor phase had great advantages. The latter process significantly saved raw materials, it was very convenient to operate, and the work efficiency was greatly improved.With activated alumina as the support, copper and nickel as the main component, zinc and magnesium as catalyst additives, Cu-Ni-Zn-Mg/Al2O3catalyst was prepared with and without ultrasonic treatment during the impregnation step. The physicochemical properties and microstructure of the catalyst were analyzed by means of ICP, XRD, BET and SEM. Compared to the conventional impregnation method, the catalyst prepared with ultrasound had higher activity, because the content of copper increased from3.96%to4.92%, the content of nickel increased from1.75%to2.07%, the surface area increased from92.11m2·g-1to107.47m2·g-1, the pore volume increased from0.33cm3·g-1to0.36cm3·g-1, and active ingredients could be better dispersed in the support. The optimized ultrasonic power and ultrasonic time were245W·m-2and2h respectively.The optimized conditions of morpholine were investigated through single factor and orthogonal experiments, as follows:230℃,1.8MPa,0.15h-1, and the molar ratio of ammonia to diethylene glycol was5:1. The conversion of diethylene glycol was99.87%, and the yield of morpholine was91.22%. Factors affecting the yield of morpholine were the reaction temperature, descending space velocity of diethylene glycol, pressure and molar ratio of raw material. A part of hydrogen of the reaction system was replaced with nitrogen.