Shestakova, Pavletta published the artcileHybrid catalyst with combined Lewis and Bronsted acidity based on ZrIV substituted polyoxometalate grafted on mesoporous MCM-41 silica for esterification of renewable levulinic acid, Computed Properties of 539-88-8, the main research area is Lewis acidity Zr polyoxometalate mesoporous zeolite esterification catalyst; Bronsted acidity Zr polyoxometalate mesoporous zeolite esterification.
Materials which synergistically combine Lewis and Bronsted acid properties hold potential for applications as efficient heterogeneous catalysts for preparation of biofuels and biolubricants. Herein we report new heterogeneous catalysts based on grafting the intact Lewis metal (ZrIV) substituted Keggin polyoxometalate (POM) on mesoporous silica support. A new approach for immobilization of the POM in MCM-41 silica was developed by co-condensation of Si source (tetra-Et orthosilicate, TEOS) with POM salt in the presence of a template mol. as an alternative to the commonly used acidic POM form and impregnation procedure for catalyst preparation The proposed synthesis method in combination with extraction of the template proceeded with preservation of the intact POM structure and resulted in hybrid catalysts with in situ generated Bronsted acid sites in addition to the Lewis acidity provided by the metal centers. Textural properties of the catalysts were characterized by X-ray diffraction, N2 physisorption and transmission electron microscopy (TEM). Insight into POM stability and structural transformations during synthesis, template removal and impregnation was provided by solid state 31P and 29Si NMR spectroscopy. Catalytic activity was studied in esterification reactions of levulinic acid with ethanol or octanol to value-added esters. The directly synthesized POM-functionalized hybrid catalysts exceeded the post synthesis impregnated ones, demonstrating significantly higher catalytic activity, recyclability and resistance against leaching. The proposed approach for immobilization of Lewis metal POMs in MCM-41 silica framework with in situ generation of the active Bronsted acid sites opens prospects for the development of efficient hybrid catalysts for esterification reaction, which overcomes the main limitations of common POM based catalysts such as low stability of the acid sites during the synthesis and the catalytic reaction, low surface area, agglomeration of the catalytically active phase and low stability of the Lewis metal center in presence of water.
Microporous and Mesoporous Materials published new progress about Agglomeration. 539-88-8 belongs to class esters-buliding-blocks, name is Ethyl 4-oxopentanoate, and the molecular formula is C7H12O3, Computed Properties of 539-88-8.
Referemce:
Ester – Wikipedia,
Ester – an overview | ScienceDirect Topics