VCM conversion catalyst issue
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Why does a new catalyst need to be activated before use? Also, please discuss the temperature variations and usage time requirements for the new catalyst, as well as the precautions to take.
Catalyst activation is intended to reduce the harm of acetylene to mercury chloride! Improve the efficiency of catalyst use! Because acetylene can reduce mercuric chloride to metallic mercury, calomel, or mercury, thereby deactivating the catalyst! For the new catalyst, the temperature should be kept below 140 degrees; the duration of use depends on the actual circumstances
For new catalysts, here we require proper control of temperature and the air intake volume to the converter. Because the new catalyst has good activity, the reaction is quite intense
The control is primarily achieved by regulating the space velocity of acetylene. During the initial stage of the reaction (up to 1000 hours), which corresponds to the “adolescent phase” of the catalyst, its activity is very high; therefore, a lower space velocity should be maintained, otherwise the reaction becomes intense and the temperature rises (to 250–300°C). From 1000 to 3000 hours, it is the “prime of life” for the catalyst, and the space velocity can be increased to its maximum value. After 3000 hours, in the “old age” phase, increasing the amount of acetylene fed in or raising the space velocity no longer results in a rise in temperature. When the acetylene concentration at the outlet of the converter reaches 3%, the operation should be reversed. (Transferring the second-stage catalyst to the first stage)
The catalyst* used in our factory has already been activated by the supplier; all that’s needed is to pay attention to controlling the temperature when starting its use.
Catalyst activation is intended to reduce the damage caused by acetylene to the catalyst! Increase the catalyst’s usage time! Because acetylene can reduce mercuric chloride to metallic mercury, causing the catalyst to lose its activity! For the new catalyst, the temperature should be kept below 130 degrees; it can be increased gradually after 200 hours!