Zeolite beta nanosponge with high acidity on mesopores for efficient tributyrin transesterification

초록

The demand for technologies that convert waste bio-oils and fats into hydroprocessed esters and fatty acids (HEFA), used as biofuels for decarbonizing long-distance transport, has increased significantly. Here, we present a zeolite beta nanosponge synthesized using a structure-directing surfactant. This material features a highly mesoporous architecture formed by ultrathin (similar to 5 nm) zeolitic frameworks. We demonstrate its effectiveness in the catalytic pre-treatment of fat-derived molecules by using tributyrin transesterification. It is a key step prior to hydroprocessing into liquid hydrocarbons. The reaction was conducted in a batch reactor at 373 K using a 1:60 M ratio of tributyrin to methanol. Due to the bulky nature of tributyrin, catalysis primarily occurs at acid sites on external surfaces and mesopore walls, rather than within internal micropores. As a result, the zeolite beta nanosponge showed a 13.5-fold higher catalytic activity than commercial zeolite beta with limited mesoporosity. It also outperformed Al-MCM-41, a mesoporous material with fewer strong acid sites. Furthermore, the catalyst maintained its crystalline structure and acidity over five consecutive reaction cycles.

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