Reduction issues in cobalt-molybdenum hydrogenation catalysts
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This post was last edited by *nyang3390 on 2012-3-28 23:03. The hydrogen production unit operates at an extremely low load, using only residue oil enriched in hydrogen (with a hydrogen content of nearly 80% and virtually no sulfur) as raw material. The cobalt-molybdenum hydrogenation reactor is kept at a normal temperature of 350 degrees; over time, could the cobalt-molybdenum hydrogenation catalyst be reduced? I’ve brought this up with my supervisor, but they said it doesn’t matter and there’s no issue, so I’m asking those who are experts in hydrogen production: can this system operate for a long time under such conditions?
The main reasons for the deactivation of residue hydrogenation catalysts are the blockage of the catalyst’s pores by large-sized molecules, coking, and metal deposition on the catalyst surface, all of which lead to deactivation. A high hydrogen-to-oil ratio is harmless to the catalyst.
I am asking about the cobalt-molybdenum hydrogenation catalyst used in hydrogen production units, not that used for residue oil.
I’m not very familiar with this process. We use cobalt-molybdenum catalysts in ammonia synthesis as well; initially, the components are cobalt oxide and molybdenum oxide, and after heating for sulfidation, they become cobalt sulfide and molybdenum sulfide – these are the active components of full low-temperature shift catalysts. Generally, reverse sulfidation occurs when the amount of hydrogen sulfide entering the system is low or when there is too much steam added. I’m not sure how you control the furnace temperature; if it can be maintained at 350 degrees, then there should be no problems, provided that the electric heater isn’t used. Hydrogenation reactions are exothermic, and the furnace temperature is maintained by the heat generated by these reactions; if the temperature can be kept stable, the system will function properly. It's just my personal opinion; feel free to criticize!
This post is great~! I’m really curious about this question too; I hope an expert can answer it~! Wait. . . . . . .
80% hydrogen content? Why not feed it directly into the PSA without applying pressure? In general, the hydrogen content in gas produced from dry gas is less than 75%.
You can consult the catalyst manufacturers; they know best.
This can be determined by comparing the degree of hydrogenation and the properties of the product after the device has been operating for a certain period of time with those at the initial stage, to see what the differences are; of course, this must be done within the operational lifespan of the catalyst. If the hydrogenation activity decreases significantly, intermittent sulfur addition can be employed to suppress the reduction of metal sulfides.