Study On The Catalysts For Methyl Chloride Synthesis From Ammonium Chloride And Methanol

Ammonium chloride is the main by-product in the production of soda andAminoacetic acid. How to efficiently utilize ammonium chloride has become thebottleneck of the soda development. A process to react ammonium chloride with methanolto produce chloromethane was proposed by our research group. This process can not onlysolve the resource utilization of ammonium chloride, ammonia recycling, but also producehigh value-added product chloromethane. For this reaction process, the selection of highefficient catalyst is essential. The bench-scale experiments on the selection of catalyst andoptimum of operation conditions have been carried out in our lab since2005. A newcatalyst with good activity was selected, however the deactivation of the catalyst occurredwhile long reaction time. In this thesis, the catalysts were further selected, the lifetime ofcatalyst with alumina as carrier was researched, the mechanism of catalyst deactivationwas also deplored. In order to find suitable catalyst carrier and the catalyst with longlifetime, the catalysts were prepared with zeolite catalyst and activated carbon as carrier.With incipient impregnation method, the composite catalysts were prepared. Theresults showed that alumina catalyst activity was high and the lifetime achieved361h.With characterization methods of fluorescence elemental, thermogravimetric, specificsurface area and infrared absorption spectrum and XRD, new catalyst, used catalyst with79hour reaction time and with361hour reaction time were researched. The resultsshowed that the catalyst deactivation was due to carbon deposition on catalyst, andespecially due to the hydrothermal reaction of alumina carrier under high temperature andFe, water vapor and HCl, which caused the change of the catalyst structure and theformation of new substance. This new substance was confirmed to be basic chloridealuminum. With improved reaction device, the activity of catalyst with carrier of aluminais good and the lifetime of the catalyst may be as long as928h.The catalysts with zeolite and activated carbon as carrier were prepared to replacealumina. It is found that the deactivation of the catalyst with carrier zeolite is due toimproper regeneration condition. The optimum regeneration conditions of catalyst withzeolite were then deplored, and the results are: total flow rate,34ml/min,in which the airand nitrogen flow rate ratio of1:1, temperature to550℃in1h, and at the temperature of550℃for5h.For the catalyst with activated carbon as carrier, when zinc chloride is as theactive component, better activity and the higher yield of chlorine methane can be achieved, and the preparation conditions are: heat treatment temperature,200℃; calcinationtemperature,300C.