Hydroconversion of n-hexadecane over bifunctional microporous and mesoporous model catalysts. Influence of pore architecture on selectivity

• An hydrocracking catalyst has been prepared by alumination of a MCM-48 silica.
• It shows a higher selectivity toward isomerization than Y-type catalysts.
• Primary hydrocracking products result preferentially from central cracking.

A model hydrocracking catalyst with a narrow and homogeneous distribution of mesopores of 3.2 nm of diameter has been prepared by alumination of the surface of a siliceous MCM-48 material, loaded with platinum and evaluated in the hydroconversion of n-hexadecane. Compared to zeolite catalysts featuring a similar acidity but containing both micropores and mesopores, the Pt/Al-MCM-48 catalyst leads to the same overall activity but with higher hexadecane isomer yields and a symmetrical repartition of the cracked products, typical for primary central cracking, even at very high conversion levels. It is suggested that the unique behavior of the model Pt/Al-MCM-48 mesoporous hydroconversion catalyst is due to optimal sorption energetics of the primary reaction products in the network of uniformly distributed mesopores.

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