Starting method of catalyst

The starting method and procedure have great influence on the activity, selectivity and life of catalyst.If the method of operation is not proper or wrong, the activity of catalyst will be lost, the selectivity will be poor, and the life will be shortened. A typical start-up process consists of three steps: drying, prewetting, and presulfuration.

Drying of catalyst

Most catalytic hydrogenation catalysts take porous material as the carrier, the water absorption is very strong, generally up to 3%~5%. The wet catalyst is in contact with hot oil and gas,  the water vapor vaporizes quickly. The downward water vapor is condensed and adsorbed by the lower cold catalyst, and a lot of heat is released, which is easy to lead to the catalyst crushing. The repeated vaporization-condensation process of water may also affect the pre-vulcanization effect and reduce the catalyst activity. Therefore, it is very necessary to dry the catalyst when starting.

The main steps of drying are as follows:

The device is air-tight, after hydrogen replacement is qualified, the circulating compressor is turned on for nitrogen cycle in maximum quantity,  the temperature rises to 200~250℃ at 15~30℃/ hour, the constant temperature is maintained for a period of time. When the hourly water output of the separator is less than 0.01% of the catalyst storage, the heating and nitrogen cycle can be stopped, then the vacuum is pumped, and the dehydration is further stepped, then the nitrogen pressure is boosted.