(600l) The Industrial Application of the Catalyst for Removal the Trace Olefin From Aromatics

In a refinery, aromatic hydrocarbon which can be obtained from reforming and cracking process always contain undesirable trace olefins ¹ which are harmful to the followed technological processes and the applications of aromatics. ²Two processes have been discovered for removing trace olefins from aromatic³ (i.e., particulate clay treating and catalytic hydrogenation treating). However, both have some drawbacks, for example, the clay have very limited lifetime. Pressure from legislative and environmental bodies together with a growing awareness within the chemical industry has led to a search for new eco-friendly products and processes to replace polluting reactions.

The side-stream test⁴ had demonstrated that the catalyst developed by our research team ould prolong the lifetime more than the commercial clay. Then catalyst production has been successfully scaled up from lab to industrial scale and 100 tons catalyst had been used in the 450Kt PX combination units in Sinopec Zhenhai Refining and Chemical Company. The operation parameters were the same as the clay treatment while the effective running time about 3.5 times as long as that of the commercial clay. It should be noticed that treating of such process stream also does not significantly change the quantity or distribution of the aromatic hydrocarbons treated.

Pyridine-FTIR was used for exploring the mechanism of the reaction. The result should that the increase of the weak Lewis acid was the main reason for the enhancement of the catalyst activity. Further researches indicated that the olefin react with aromatics via the generally accepted carbenium ion mechanism and the reaction was the typical alkylation reaction.