Mechanistic insight into the catalytic cracking mechanism of α-olefin on H-Y zeolite: A DFT study

Abstract

In the bifunctional catalyst for Fischer-Tropsch synthesis, the distribution of products in the secondary catalytic reaction of intermediate products is affected by the Brønsted acid sites in zeolites. Linear α-olefins are the intermediates of Fischer-Tropsch synthesis. In this work, density functional theory (DFT) calculation was carried out to understand further Brønsted Acid Sites’ mechanism in the secondary reaction of Fischer-Tropsch synthesis. The adsorption energy of linear α-olefins on H-Y zeolite decreased with the increase of the carbon chain. Besides, four essential reactions were simulated by the DFT method. The four elementary reactions' energy barriers are: β bond-breaking reaction > skeleton isomerization reaction > intramolecular hydrogen transfer reaction > protonation reaction. Then, a complete reaction network of straight-chain α-Nonylene on H-Y zeolite was designed. The β bond-breaking reaction is a key step to determine the type and distribution of products.