Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
59922 | Chinese Journal of Catalysis | 2013 | 7 Pages |
Catalytic conversion of methylcyclohexane was studied on four specially designed HZSM-5 zeolites. A careful steam treatment was used to produce pair-sites composed of a Lewis acid site, due to extra-framework Al species from the dealumination by steaming, and a Brönsted acid site, due to bridging hydroxyl in the steamed HZSM-5. The spatial proximity of these component acid sites of the pair-site was verified by 1H double quantum magic spinning NMR. Product selectivities of methylcyclohexane conversion showed the same trend for all the samples, which indicated that the pores of the zeolites were not changed by the steam treatment. The Lewis acid site that was created, however, gave a synergistic effect with the Brönsted acid site in the pair-site, which gave higher conversions and cracking rates of methylcyclohexane. The rate of methylcyclohexane conversion increased with increased concentration of extra-framework Al, which gave more pair-sites.
Graphical abstractA synergistic effect between Lewis and Brönsted acid sites in steamed HZSM-5 zeolites accelerated the conversion and cracking rate of methylcyclohexane conversion.Figure optionsDownload full-size imageDownload as PowerPoint slide