Effects of nanosheet catalysts on synthesis of aromatics and light hydrocarbons from acetylene

A nanosheet zeolite ITQ-2 formed by delamination of MCM-22 zeolite precursor was used and tested as a catalyst for the aromatization of acetylene. Along with MCM-22 (calcined form of MCM-22 zeolite precursor) zeolites, the resulting materials were successfully prepared and characterized in terms of pore structure and surface property. The performance of aromatization of ITQ-2 zeolites was comparable to that of MCM-22 zeolites. Due to the isolated and thin-layer structure, ITQ-2 zeolites had a significant fraction of external active sites. This feature seemed to result in relatively higher amount of C3–C8 aliphatic compounds rather than the C6–C8 aromatic compounds because of the shortened residence and, thus, reaction time. We first found that the cumulative C3–C8 aliphatic products in the case of ITQ-2 zeolites increased with the amounts of external surface area, while no clear relation was observed for the case of MCM-22 zeolites. Second, the initial selectivity towards aromatics was found to clearly show a linear relation with the concentration of Brønsted acid sites regardless of the used catalyst. In addition, the nanosheet ITQ-2 zeolites showed a much slower deactivation unlike the traditional microporous MCM-22 zeolites. Finally, to investigate the difference in the catalytic performance, we rebuilt the reaction pathways from acetylene to the aromatics and aliphatics.