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This post was last edited by mrzhouyi on 2011-4-23 at 18:13. As my English is not very good, I am asking experts to help translate the following Chinese summary into English. Thank you in advance. Research on the production of trichlorosilane from HCl by-product of R22. Currently, the production of trichlorosilane in China mainly relies on the boiling method, which involves using HC1 (or Cl2 and H2) along with metallurgical-grade industrial silicon as raw materials, and reacting them in a fluidized bed to produce a reaction mixture that primarily contains trichlorosilane. The hydrogen chloride used as raw material in its production is synthesized from hydrogen and chlorine; the main reactions are: (1) H2 + Cl2 → 2HCl, (2) Si + 3HCl → SiHCl3 + H2. The main side reaction is: (3) Si + 4HCl → SiCl4 + 2H2. Since the hydrogen chloride used in these reactions contains essentially only hydrogen chloride and excess hydrogen, with no other impurities that could participate in chemical reactions. The R22 production facility with an annual output of 10,000 tons, developed and built by the company in 2004, has been operating stably for many years. The technical level of its production equipment, raw material consumption, and product quality all reach the best standards in the country. With an annual production capacity of 10,000 tons of R22, the production facility generates over 11,000 tons per year of high-purity hydrogen chloride; this hydrogen chloride is absorbed using water to produce by-product hydrochloric acid with a concentration of 31%, which is then exported. As a result, the high-purity hydrogen chloride is not utilized effectively. The reason why the company is conducting experimental research on using hydrogen chloride produced as a by-product of R22 to manufacture trichlorosilane is to make full use of the 98% high-purity hydrogen chloride available. However, it differs from synthetic hydrogen chloride in the following ways: 1) It contains a higher proportion of HCl as its main component, which should be favorable for the reaction ； 2) It has a low water content, with the water level being below 50 ppm, which also contributes to a higher yield of the reaction. 3) It contains chlorofluorocarbons, which may participate in the reaction and affect its yield; this is also the reason why this topic was proposed. Studies conducted using the company’s 1kt/a test facility have shown that the chlorofluorocarbons present in hydrogen chloride, primarily R22, R13, and R23, have a highly significant impact on the synthesis of trichlorosilane. It was also found that when the content of CFCs in hydrogen chloride is low, its impact on the system can be kept under control. If the CFC content in hydrogen chloride can be reduced to below 1%, it is feasible to use it as a raw material for the production of trichlorosilane; indeed, when the CFC content in hydrogen chloride reaches 1%, the trichlorosilane content in the crude trichlorosilane product exceeds 80%, which is already at an intermediate level in the industry. Studies show that it is feasible to produce trichlorosilane using hydrogen chloride produced as a by-product of R22, provided that the content of chlorofluorocarbons in the raw hydrogen chloride is strictly controlled (below 1%).