Promoting Syngas to Olefins with Isolated Internal Silanols-Enriched Al-IDM-1 Aluminosilicate Nanosheets

Selective conversion of syngas to value-added olefins has attracted considerable research interest. Regulating product distribution remains challenging, such as achieving higher olefin selectivity, propylene/ethylene (P/E) and olefin/paraffin (O/P) ratios. A new pentasil zeolite Al-IDM-1 with recently approved −ION structure, composed of 17-membered-ring (MR) extra-large lobed pores and intersected 10-MR medium pores, shows a C_2–6⁼ selectivity up to 85 % and a high O/P value of 14 in the conversion of syngas when being combined with Zn_aAl_bO_x oxide. Moreover, for the high-silica Al-IDM-1 with Si/Al ratio of 400, the selectivity of propylene and butene accounts for 88 % in C_2–4⁼, resulting in high P/E (>4) and butene/ethylene (B/E >3) ratios. The high C_3–4⁼ selectivity is contributed by two main reasons, that is, the relatively weak acidity of Al-IDM-1 zeolite enhances the olefin-based cycle revealed by the probe reactions of methanol-to-propylene (MTP) and 1-hexene cracking, and the rich isolated internal SiOH groups in Al-IDM-1 promote the desorption of C_3–4⁼, once they are formed inside zeolite pores.