I have a question regarding the feeding method for hydrogenation reactors; I would appreciate it if experts could provide an answer. Thank you!
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The C4 feedstock hydrogenation reactor in our company is primarily used to saturate unsaturated hydrocarbons such as olefins through hydrogenation, as well as to purify and remove compounds containing sulfur, nitrogen, and oxygen. The feed enters the reactor from the top and exits from the bottom. A company adjacent to them is engaged in alkylation; their raw material is butene after etherification. In the hydrogenation pretreatment stage, the butadiene component undergoes an addition reaction to produce 1-butene, which is then isomerized into cis- and trans-2-butene. However, in all hydrogenation reactors, the material flows from bottom to top. Question: Since it is both hydrogenation, why are different feeding methods used? Why is it designed this way? What is the reason?
The process of material flowing upward and downward is known as a trickle bed. The reaction temperature rises significantly, and it is difficult to control the temperature of the bed layer. Since unsaturated hydrocarbons are converted into saturated hydrocarbons, it is sufficient to control the inlet temperature and prevent the bed layer from overheating； A bed with material entering from below and exiting from above is called a bubble column bed; the temperature of such a bed is easy to control. This type of bed offers good catalyst selectivity, as the butadiene content in the C4 alkylation pre-hydrogenation feed is low. If not controlled properly, the olefins will be hydrogenated, affecting the yield of monolefins
What is the process for hydrogenation pretreatment? Is just one hydrogenation reactor sufficient?