Study On The Pilot-scale Experimental For Methyl Chloride Synthesis From Ammonium Chloride

Ammonium chloride (AC) is a by-product in the production of soda. In2009, theoutput of AC is8.20million tons in China. AC is mainly used as fertilizer in agriculture,however it is limited to use due to its high chloride content, there is a disadvantage ofdamaging to crops and soil, which results in massive excess of AC. It is a way to consumeAC to transfer it to other industrial products. Up to now, there is little research on it, andthere is no report on the industrialization of this process.The preparation of chlorine methane with AC and methanol was studied by ourresearch group these years. The catalyst for these process has been prepared and selectedin a bench-scale experimental setup, in which fixed bed reactor was applied, In this study,based on the batch production of catalyst, pilot-scale experiments were further carried out.Firstly, the process of ammonium chloride decomposition was studied in this thesis.With BET instrument for examination of specific surface area and microscope forobservation of the shape of AC during decomposition, it can be concluded that thedecomposition of AC is in a way of shrinking of unreacted core and it is non-porous. WithThermo Gravimetric Analyzer(TGA), the kinetics of AC decomposition were studied. Theexperimental results showed that the mechanism is one-dimensional phase boundaryreaction, and the kinetic equation is α=kt.According to the preparation of the catalyst in bench-scale experiments,equal-volume impregnation was employed in the batch production of catalyst. Acatalyst-preparing device with the preparation capacity of15kg catalyst per batch wasmanufactured. The key devices in pilot-scale hot-model experimental setup wereimproved and the methods of product analysis are refined. In the hot-model experiments,the optimum conditions were studied and determined. The optimum temperature arebetween310℃and350℃; molar ratio,1.1～1.3:1; space velocity,10min-1. Under theseconditions, the yield of methyl chloride is up to77.1%. The experimental data wereconfirmed through the carbon balance between the inlet and exit of the reactor. The carbonbalance is more than93%in the pilot experiments, and it can basically meet the need forfurther industrialization. The deactivation of catalyst was also examined and it isconcluded that the main reason of catalytic deactivation were carbon deposition andpoisoning。...