Search

To handle huge amount of glycerol produced in biodiesel industry, glycerol is transformed to value-added products. In this regard, glycerol acetalization to solketal is industrially attractive. As in this process various by-products can be formed, designing highly selective catalysts is of great importance. In this line, we wish to report a novel catalyst that benefits from strong acidity, high specific surface area and thermal stability, which can selectively form solketal in glycerol acetalization. To prepare the catalyst, hierarchical zeolite was prepared via a novel method, in which partially dealuminated NaY was treated with PluronicF-127 and then reacted with NH4NO3 to furnish the H-form zeolite. Hierarchical faujasite was then achieved through calcination and template removal. Subsequently, it was functionalized with ionic liquid and used for the immobilization of heteropolyacid. The results indicated the importance of the mesoprosity of zeolite and the presense of ionic liquid functionality for achiveing high solketal yield. Moreover, among three investigated heteropolyacids, phosphomolybdic acid exhibited the highest catalytic activity. In fact, using 10 wt% catalyst at 55 °C and glycerol to acetone molar ratio of 1:20, solketal with yield of 98% was furnished under solvent-less condition. Besides, the catalyst was recyclable with low leaching of heteropolyacid. [ABSTRACT FROM AUTHOR]

Two lanthanide-coordination polymers (Ln-CPs) containing benzophenone-4,4′-dicarboxylate (bpndc2−) linker, namely [Er2(bpndc)3(DMF)2] (1) and [Yb2(bpndc)3(DMF)2] (2) were synthesized and characterized using X-ray crystallography and spectroscopic methods. The topological analysis revealed that both compounds are chiral three-dimensional uninodal 5-connected net of type yfh. These Ln-CPs showed good stability and thus were used as heterogeneous catalysts for the acetalization of glycerol. This study provides some further evidence supporting the effectiveness of Ln-CPs as potential Lewis acid catalysts for chemical transformations. [ABSTRACT FROM AUTHOR]

[Display omitted] With the aim of benefiting from the catalytic activity of metal organic frameworks and zeolites and the possible synergistic effect between them, two novel composites, composed of MIL-101 and ZSM-5 zeolites with different SiO 2 /Al 2 O 3 ratios were synthesized via surface functionalization of ZSM-5 zeolites and their hydrothermal treatment with MIL-101 precursors. Characterization of the composites confirmed formation of MIL-101 in the presence of ZSM-5 zeolite. Moreover, it was revealed that the textural properties and acidity of the composite were influenced by SiO 2 /Al 2 O 3 ratio and the one with lower SiO 2 /Al 2 O 3 ratio showed higher acidity. The catalytic activity of the composites was then appraised for Knoevenagel condensation reaction under mild reaction conditions. Gratifying, the composites showed high catalytic activity, higher than their individual components, indicating the synergism between ZSM-5 and MIL-101. Broad substrate scope, facile recovery of the catalyst and its high recyclability were other merits of the present protocol. [ABSTRACT FROM AUTHOR]