Process Optimization And Technical Transformation Of Thiol Methyl Tin

The methyl tin mercaptide due to its excellent initial coloration and excellent stability of thermal stabilizer later became popular in the PVC machining process. Aim to Yunnan Tin corp. chemical materials company 2000 tons/year of mercaptan methyl tin production line, which the production efficiency was not high, technical and economic indexes were low, compared with the design production capacity and index the huge gap was existed, researches were did.The esterification reaction process in methyl tin mercaptide production were optimized. The results showed that suitable technological conditions:pre esterification temperature was 27.5℃, pre esterification reaction pH 3.5, esterification temperature 50℃, distillation temperature 110℃, the end of the pre esterification pH 8.5, under the conditions, the tin straight yield and yield were above 99%.Researching and analyzing from the following aspects, process optimization and transformation plan were proposed:(1) Preparation of tin raw material improvements:The optimum process parameters were determined by test, temperature 20℃, tin melting temperature 320℃, pressure 0.3MPa, Class D drying equipment was selected, raw material tin was more favorable for the reaction, the reaction time was shorten to 4 hours; (2) Monochloromethane transportation material equipment selecting:the three transport equipment were used and compared, shield pumping was selected for smooth, easy operation and low security risks; (3) Intermediate synthesis catalyst selecting:Three types of catalyst were compared in production from catalytic efficiency, life cycle, the impact on the equipment, etc., N compound was determined as catalyst; (4) Tin reactor structural optimization:By improving stirred paddle and kettle structure, maintenance cycle and time were significantly reduced, the equipment start-up time was effectively improved; (5) Distributing agent added approach:The distribution agent was added gradually in batches, the intermediate trimethyl tin chloride content decreased from an average of 0.288% to 0.154%, so that the content of three methyl mercaptan tin of methyl mercaptan tin products achieved Chinese Disease Control and Prevention Center detection LD50 to 3.16g/kgBW, to achieve world-class level; (6) Improved intermediate distillation process:increased cooling heat transfer area, canceled the dissolution kettle cover heating, dissolving tank operation at low temperature, to improve production efficiency and product quality; (7) Neutralizing agent selection: using ammonia as neutralizing agent, low cost, convenient transportation, the production process easy control; (8) esterification metering equipment upgrade:the reaction was controlled by the manual to automatic control, benefit for process control and product quality stability; (9) study of thiol esters:through the test and adjustment of the reaction parameters, the burden coefficient, the consumption of thiol esters was dropped to 0.782 tons/ton from 0.804 tons/ton; (10) Optimization of the preparation technology of a single high mono methyl intermediate:the optimized high mono methyl intermediate preparation was easy operation, tin yield increased significantly.After the implementation of technological improvements, the production of methyl tin product was improved, the main technical and economic indicators were steadily improved, the product quality was stable.