Several issues related to cold hydrogenation
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1: Among the existing thousand-ton-scale production lines in operation, which ones use cold hydrogenation technology? What is the actual effect? 2: What is the typical range of reaction pressure achievable with cryohydration technology? What catalyst to use? 3: What are the most pressing issues that need to be addressed in cold hydrogenation for current production? 4: Some companies refer to the technologies related to chlorohydration when carrying out cold hydridation. What are the similarities between them? What can be learned from? Thermal hydrogenation is energy-intensive, and practice has shown that it is not the most effective method for dealing with silicon tetrachloride at present. Cold hydrogenation represents the future trend, but our related technologies are not particularly advanced; it seems that only a few capable companies in China are using this technology. Those among us who are interested in learning more about or participating in cold hydrogenation processes are welcome to share their knowledge and engage in more discussions!
There is no fundamental difference between cold hydrogenation and chlorohydration
1. Zhongsi Zhongneng employs cold hydrogenation, achieving a conversion rate of over 20% and maintaining stability. 2. The reaction pressure can generally be controlled within the range of 20–30 Kg. Raney nickel or copper(I) chloride catalysts are generally used. 3. The main problems that need to be addressed urgently include: blockages in the pipes caused by silicon powder, equipment damage due to localized overheating inside the reactor, and ensuring continuous stable operation. 4. Cold hydrogenation is represented by medium silicon, with no hydrogen chloride added to the reactor ； Chlorohydration is represented by medium-energy processes, and the hydrogen chloride produced by reduction is introduced into the hydration fluidized bed to participate in the reaction.
Reply to 3# zhangweicheng: Thank you, the answer was very detailed. I would like to ask whether, in the case of cold hydrogenation, hydrogen chloride that does not need to be recovered can be disposed of directly? How should it be handled?
It can be hydrolyzed, or evaporated and concentrated to produce hydrochloric acid, or used in the synthesis of trichlorosilane
What is the general formula for calculating the primary conversion rate of silicon tetrachloride?
Cold hydrogenation is an endothermic reaction; why does local overheating occur and damage the equipment? !
The reaction takes place in the presence of hydrogen chloride, which is equivalent to the synthesis reaction of trichlorosilane
How are the products obtained through cold hydrogenation recovered? Is a separate exhaust gas recovery device needed?
The amount of hydrogen chloride is very small compared to silicon tetrachloride and hydrogen; the heat released during the synthesis reaction is far less than the heat required for the reaction. I’m not sure what method is used to heat the reactants in the cold hydrogenation reaction you mentioned
Indirect heating is achieved through the vaporization of silicon tetrachloride, so no heating is required for the reaction process