12-Phosphotungstic acid immobilized on activated-bentonite as an efficient heterogeneous catalyst for the hydroxyalkylation of phenol

Bentonites Modified with Phosphomolybdic Heteropolyacid (HPMo) for Biowaste to Biofuel Production

“…Heteropolyacids (PAHs) with Keggin-type structure have been of great interest in the field of acid catalysis [12], because of its acidic properties and high catalytic activity [13,14]. However, they are unsuitable for esterification because of their high solubility in polar media [15,16,17]. An alternative to overcome this problem could be to support these heteropolyacids on a solid with a high surface area, such as MCM and SBA [9,18,19], metakaolin [9,20], Zirconia [21,22], montmorillonite [13,16,23,24,25,26] and others.…”

“…Montmorillonites are hydrophilic clays of bentonite type, with a layered structure and have been investigated as environmental and reusable catalysts [28,31]. Montmorillonite clay is among various layered aluminosilicates, consists of layers of two tetrahedral silica sheets sandwiching one octahedral alumina sheet, which has caught great attention especially due to its good swelling property and high exchange capacity, which is abundant on the earth [16,32]. The ability of exchangeable ions in their interlayer spaces allows the introduction of various metals, heteropolyacids and physiological functions between the layers, in addition to acid activation [1,13,24,25,33,34,35,36,37].…”

“…The ability of exchangeable ions in their interlayer spaces allows the introduction of various metals, heteropolyacids and physiological functions between the layers, in addition to acid activation [1,13,24,25,33,34,35,36,37]. Both the modified-bentonite and bentonite are promising supports due to their common fascinating features, such as their inherent acidity, excellent thermal stability, and easily controlled structure and morphology [16].…”

“…The catalytic effects of PAHs in acidic reactions depends on three factors: acidity, heteropolianion structure and the type of reaction. On the other hand, clays may be used as catalyst support [9,13,16,20,25,26,34,41,44], or act as acid catalysts [7,8,38,39], redox catalysts and in removing heavy metals from the environment from modifications [45,46]. Both the modified-bentonite and bentonite are promising supports due to their common fascinating features, such as their inherent acidity, excellent thermal stability, and easily controlled structure and morphology.…”

“…Both the modified-bentonite and bentonite are promising supports due to their common fascinating features, such as their inherent acidity, excellent thermal stability, and easily controlled structure and morphology. Therefore, the modified-bentonite with larger specific surface area is widely used as a very good catalyst carrier [5,13,16,24,25,41,47]. Actually, heteropolyacid-impregnated solid acids have caused great interest in many fields.…”