Xinan Chemical Takes the Lead in Organo-silicon

At present, the activities and expansions in organo-silicon industry in China is in full swing and vibrant once more. Organo-silicon deep-processing enterprises are emerged increasingly while methyl chlorosilane domestic producers are rivaling for expansions or building new capacities. Jiangxi Xinghuo Chemical Works (ChemChina), Zhejiang Xinan Chemical Industrial Group Co., Ltd., and CNPC Jilin Chemical Co., Ltd. are the three leading players in China, and they almost dominate the domestic market. Amongst, Xinan Chemical has taken the lead in organo-silicon industry with regards to monomer production, downstream products scales, product qualities and byproduct comprehensive applications. Anyhow, Xinan Chemical has broken a new path with its characteristics in organo-silicon industry.

A. Methyl Chlorosilane Monomer ScaleAs a matter of fact, the capacity of organo-silicon in Xinan Chemical was no more than 1 000 t/a in 1980s, and the output of methyl chlorosilane monomer was stabilized at 1 000 t/a in the middle of 1990s. In 1997, the capacity had been 3 000 t/a and then it was increased up to 5 000 t/a in 1998 after renovation. At the end of 2000, it had been renovated once again and expanded capacity to 7 000 t/a. In 2005 its organo-silicon production scale jumped to 70 000 t/a.

B. Selectivity Selectivity of dimethyl dichlorosilane is the know-how when producing methyl chlorosilanes. Xinan Chemical obtained a significant improvement on the selectivity of dimethyl dichlorosilane, reaching 82%-87% at present.    Firstly, the company established the special production standards of silicon powder used for synthesizing methyl chlorosilane. According to the composition of silicon powder, it is necessary to adjust catalyst formulation correspondingly. To conclude and master the rules of various impurities in silicon powder and its contents reacting on catalysts activity or products composition, the company set up the silicon powder inner-controlled quality indexes.   Secondly, the catalyst used by Xinan Chemical has been changed to Silicon-Cupric-Zinc-Tin-Phosphorus five-metacharacters catalyst instead of Silicon-Cupric-Zinc-Tin four-metacharacters catalyst. The import of phosphorus into the reaction system makes the yielding rate both of dimethyl dichlorosilane and silicane, and the conversion rate of silicon powder improved by a great extend.

C. Dimethyl Dichlorosilane QualityWhen Xinan Chemical enlarged the monomer production scale, it also enhanced the product quality. The content of dimethyl dichlorosilane was improved from 99.5% in 1980s to 99.8% in the end of 1990s. Currently, its purified dimethyl dichlorosilane by Xinan Chemical has been achieved a purity of 99.95%. Besides, DMC (Dimethyl chlorosilane) within its hydrolyzate product exhibits a very stable quality, which meets all preparation requirements for various downstream products.    In order to stabilize and enhance DMC quality, to minimize public works consumption, and to intensify methyl organo-silicon fine-distillation process, the company applies high efficiency separation apparatus. During the distillation process, it employs on-line analysis method, and continuous sample taking within a closed loop system, resulting in quick analysis. Meanwhile, it can obviously progress on-site sampling conditions, and improve the corrosion of on-site equipment pipeline thanks to no contact between samples with open air. It is more convenient for operators and workers to adjust control parameters when needed during production, and accordingly it saves energy consumption and stabilizes product quality. In the near future, Xinan Chemical is going to further increase the DMC purity, approaching foreign advanced level, 99.99%.

D. Utilizations of ByproductAt present, Xinan Chemical developed the thermal cracking technology of high-boiling-point byproducts during organo-silicon production, and realized its commercial production. In addition, it completes dismutations technology of high-boiling-point or low-boiling-point byproducts, and finishes dimethyl tri-chlorosilane conversion pilot. Amongst, the high-boiling-point or low-boiling-point byproducts dismutation has been constructed medium-scale test unit. The utilizations of byproducts not only uplifted remainder monomer application value, but reduced wastes.

E. Downstream ProductsXinan Chemical has got well along with the downstream products development. Within no more 3 years, it enlarges a 300 t/a high-temperature silicone rubber pilot production line to 20 000 t/a. Besides, it possesses the largest single-unit silicone rubber capacity in China, reaching 5 000 t/a, and its capacities of various full-compound rubbers amounts to 3 000 t/a. In addition, there are some small products including silicon oil, 107# adhesive, cross-linking agents such as anilino-methyl trimethoxy silicane, anilino-methyl triethoxy silicane and hexamethyl disilazane, having a capacities over 1,000 tons/a respectively. Meanwhile, Xinan Chemical has developed molding adhesives, high-performance key-press silicone rubber, condensation type bi-component electronic encapsulation silicone rubber, addition type silicone rubber, silicon oil for personal cares in recent years, all of them being under initial production stages.

F. Recycle of ChlorineAfter recycling chloromethane, the byproduct during pesticides production, Xinan Chemical refined the byproduct and used it as main raw materials for DMC. While, it purified hydrochloric acid formed in DMC production, and used the acid into pesticides manufacture. The comprehensive recycling applications not only realized clean production, but engendered pesticides industry chain. Currently, it even collaborates with Russia to develop high efficiency hydrolysis system for concentrated hydrochloric acid, and it can directly recover gaseous hydrogen chloride to supply chloro silicane production.