Metal-Organic Frameworks M-MOF-74 and M-MIL-100: Comparison of Textural, Acidic, and Catalytic Properties.

Abstract

The impact of the metal nature and framework type on the textural, acidic, and catalytic properties of M-MOF-74 (M=Co, Cu, Mg, Ni) and M-MIL-100 (M=Al, Cr, Sc, V) materials was evaluated. Both metal-organic framework (MOF) families showed 100 % selectivity to the tetrahydropyranyl ether for all alcohols (methanol, 1-propanol, 1-octanol, 2-adamantanol, 1-octadecanol) applied. Independently of the metal employed in the synthesis of M-MOF-74, the conversions were lower than those obtained with M-MIL-100. This result can be attributed to the combination of superior textural properties, accessibility, and strength of open metal sites in M-MIL-100 that improve the accessibility/diffusion of reactant and products. The variation of the size and shape of the alcohols on the activity and selectivity showed that the yield of tetrahydropyranyl ether decreased with increase of the alcohol size (methanol<1-propanol<1-octanol<2-adamantanol<1-octadecanol). The best catalytic results were achieved with V-MIL-100, and were even maintained after several cycles; this could be related to the superior polarizing power of V-containing units, which enhanced the activation of 3,4-dihydro-2H-pyran and, consequently, the yield of the target ether.