Q & A > Question Details
In HDS reactor the hydrogen consumption coming down when catalyst life moving to end of run ,even though the feed and product sulphur remains the same.( usually the temperature of BED have to increase for achieving the same product quality). What is the reason for this hydrogen consumption reduction?
30/06/2015 A: Sarath Konda, DuPont India, sharathsatya@gmail.com
Fresh catalyst has a higher activity and has a good hydrogenation function, which results in higher H2 consumption and has higher density reduction with better product quality. Typically during EOR, catalyst has activity declines (due to coke deposition on catalyst), which results in less hydrogenation reactions taking place with lower H2 consumption. Depending upon the type of catalyst impact on the product quality like sulfur varies. If HDS catalyst is a CoMo type, impact on product sulfur level tends to be minimal as it attacks sulfur removal directly compared to NiMo which prefers hydrogenation route. Bed temperature has to be increased at EOR to meet the product quality; increase in temperature only bridges the activity loss due to coke deposition on the catalyst.
23/06/2015 A: Saleh Daryabari, Senior Process Engineer of RCD and RFCC, Arak Refinery, daryabari@gmail.com
In HDS reactor beside HDS reaction, there is Aromatics saturation reaction that consume considerable amount of hydrogen. Aromatics saturation become lower at higher temperature. So when you increase reactor temperature during catalyst life (to compensate catalyst deactivation and keep constant product sulfur), Aromatics saturation decrease and you will have lower hydrogen consumption at EOR.