Hydrogenation of Pentadiene

For C5 alkylation, or for TAME production, removal of petandiene is required as it increases the acid consumption in alkylation and fouling in the TAME unit. The simple hydrogenation catalyst is quite sensitive to the presence of mercaptans present in this stream from cat crackers and cokers, and mercaptan removal also becomes necessary for effective hydrogenation. However, the technology of CR&L for pentadiene removal achieves both goals: hydrogenation of pentadiene and removal of mercaptans in the same unit. The mercaptans react with olefins in the presence of catalyst to form olefinic sulfides and, being high-boiling components, can be easily fractionated as the bottom product. Hence RD eliminates the mercap-tan removal step effectively. The product from the RD unit is an ideal feedstock for the TAME or alkylation unit [64].

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