The Research On Siloxane Removing Program Using The Fifty Thousand Tons Organic Silicon Device

This is a Technique Development Program from PetroChina Jinlin Petrochemical Company, co-developed by the Institute of Jilin Petrochemical Company and the Calcium Carbide Factory of Jilin Petrochemical Company. Dimethyldichlorosilane hydrolysis is a very important procedure in the production of organic silicon which converts the chlorosilanes into siloxane. The technical level of this procedure has the direct relation with the reutilization of the chlorine from most of the materials for organic silicone production. It is also the key technologies to reduce the cost of organic silicon. The constant-boiled acid hydrolysis is used by the organic silicon device in the Calcium Carbide Factory of Jilin Petrochemical Company as the hydrolysis technique which makes constant-boiled 20-22% hydrochloric acid react with dimethyldichlorosilane. After hydrolysis, the hydrochloric acid goes into the hydrogen chloride desorption device by layering and the recovered hydrogen chloride is prepared into methyl chloride to achieve the effective recycling of chlorine resource as well as improve the utilization rate of chlorine. However, constant-boiled acid hydrolysis still has the disadvantages of the high concentration of siloxane in the hydrogen chloride and the existence of siloxane in the hydrogen chloride gas. The macremolecules from the further polymerization of siloxane in hydrochloric acid will not only cause the congestion of the acid transmission pipeline, but also form the rubber-like siloxane layer in the acid containers, resulting in lower yield of siloxane, increased maintenance frequent and shortened start-up time, In addition, the siloxane in the desorbed hydrogen chloride gas will also affect the synthesis of methyl chloride. Applying the deposition approach to the hydrochloric acid after hydrolysis can effectively reduce the siloxane (siloxane consists of linear siloxane and cyclic siloxane hereinafter referred to as Linear and Cyclic). The siloxane can be reduced to 200-300ppm but this level can still seriously affect the further hydrolysis procedure, especially the quality of hydrogen chloride, the synthetic raw material for methyl chloride. The technique of removing silicone from hydrochloric acid is one of the key techniques in the constant-boiled acid hydrolysis process. In the development of this program, the reaction sulfonie acid ion exchange resin was used in the form of fixed bed reactor to apply adsorption filtration to siloxane in the acid, so as to fully remove it from the acidic water and ensure the long lasting start-up time and the effective recovery of chlorine resource. Its successful development will enhance the technical level of constant-boiled acid hydrolysis. Basing on small scale test's results, it was determined to use deposition and adsorption filtration to remove the siloxane from acid. The siloxane concentration would be reduced to 30ppm from 200-300ppm (concentration after settlement). Under the effect of buoyancy, the adsorbed glue departed from the resin and obtained fluidness available for automatic extraction. The resin would be reused after regeneration meeting the requirement of long start-up time and solving the bottlenecks during the production of organic silicon.After small scale test and lateral line extraction trial, the reaction sulfonie acid ion exchange resin was used to remove the siloxane from the acid to reduce its concentration down to 30ppm or below; reduced the Linear down to 10ppm; extended the continuous start-up time to more than 90 days. At present, there is still no other domestic technique can achieve this level.