Application Of Nickel Based Catalyst On First-stage Of Pygas Hydrogenation Unit

The Pygas hydrogenation unit from ethylene plant of Dushanzi Petrochemical Company adopts two stage hydrogenation processes for BTX production, and the hydrogenated product are feedstock for BTX units after hydrogenation. Pd-based catalyst is normal chosen as first-stage hydrogenation catalyst in this unit, but it has many disadvantages such as bad impurities tolerance, shorten lifetime and high price etc.According to the actual situation of feedstock, a new kind of Nickel based catalyst from former ICI (now HTC-200 from Johnson Matthey) was tested on 100ml and 3L units separately based on three kind of different feedstock. The best operating conditions for the hydrogenation unit were found initially after test. But the regeneration method of HTC-200 is hot hydrogen stripping at about 350℃, some revamped works were done by design department from Dushanzi petrochemical company in order to confirm operating safety in the existing unit, such as relating container, pipeline, and other materials, and a new regeneration process was built as well. When HTC-200 was loaded into reactor, the detail suitable loading method was adopted ccording to the characters of reactor and catalyst itself. As HTC-200 is eduction/passivation and presulphide version of catalyst, a controlled activation procedure is needed during the whole process for Nickel oxide removal. When catalyst as prewetted with low sulphur content prewetting oil after activation, one kind of sulphur was adding into the prewetting oil in order to reduce too much sulfur loss from catalyst surface, and advanced catalyst prewetting and start-up methods were developed for reaching its higher performance.After long time operation, the catalyst shows its higher expecting performance. Many times calibration was tested during last several months, it shows stable performance especially C5 content in the feedstock more than 8 times than design value, diene value in the product is less than 1.5gI2/100g and styrene conversion is higher than 98% than expected.