Highly selective production of di-isopropyl ether over Fe-substituted nanosheet zeolites by the 2-propanol dehydration reaction

Intermolecular dehydration of 2-propanol (IPA) to di-isopropyl ether (DIPE) serves as an important process to produce the valuable chemical, however, developing advanced solid acid catalysts with high DIPE selectivity faces the great challenge of inhibiting the intramolecular dehydration reaction. In this context, we developed a highly selective intermolecular dehydration MFI nanosheet catalyst by synergistically modifying its diffusion and acid properties. We found that the DIPE selectivity over nanosheet ZSM-5 catalysts were obviously higher than that over the conventional ZSM-5 catalyst, benefited from the enhanced diffusion property over nanosheet catalysts that inhibited the further conversion of DIPE. However, the DIPE selectivity were still lower than 70 % over those catalysts attributed to their high acid strength that facilitated the intramolecular dehydration reaction. Thus, various heteroatoms (Fe, Ga, and B) substituted MFI zeolite nanosheet catalysts were prepared and employed in the dehydration reaction, Fe-MFI with a moderate acid strength exhibited the highest DIPE selectivity among those catalysts. Besides, the effects of acid amounts (Si/Fe ratio) and diffusion properties (thickness of b-axis) on the intermolecular dehydration selectivity and activities over nanosheet Fe-MFI catalysts were systematically investigated. An optimal Fe-MFI nanosheet catalyst with the b-axis thickness of ∼20 nm and Si/Fe ratio of ∼40 presented the stable high DIPE selectivity of ∼91 % in 360 h of time on stream, meanwhile the IPA conversions kept almost unchanged.