Increasing the basicity and catalytic activity of hydrotalcites by different synthesis procedures

Co-Al Mixed Oxides Prepared via LDH Route Using Microwaves or Ultrasound: Application for Catalytic Toluene Total Oxidation

“…Similar cavitation phenomena have allowed obtaining a better catalytic reactivity of solids in the Fischer-Tropsch reaction. Recently, microwaves radiation heating [27][28][29] and ultrasound [27,30,31] have been applied to the synthesis of hydrotalcites with different chemical compositions as an alternative to the conventional hydrothermal treatments. Several of the advantages listed above have been observed, especially the shorter treatment times needed to achieve enhanced crystallinity degrees, the higher specific surface area and the improved metallic dispersions [28,32,33].…”

Influence of the Incorporation of Transition Metals on the Basicity of Mg,Al-Mixed Oxides and on Their Catalytic Properties for Transesterification of Vegetable Oils

“…anions [3][4][5][6]. The acid-base properties and, as a consequence, the catalytic activity and selectivity of these Mg,Me,Almixed oxides depend on chemical composition (type of Me cation and Mg/Me/Al molar ratio) and on the conditions of the thermal treatment used to decompose the hydrotalcite precursor.…”

“…So, they can be tailored to the process under study aiming at increasing their activity and/or selectivity. Their main applications as basic catalyst include aldol, nitroaldol, Knoevenagel, and Claisen-Schmidt condensations, alkylation of ketones and phenols, Michael additions, glycerolysis of fats for the manufacture of monoglycerides, selective reduction of unsaturated ketones/aldehydes by hydrogen transfer from alcohols, and more recently transesterification of vegetable oils for biodiesel production [2,[4][5][6][7][8][9][10].…”

Synthesis and characterisation of hydrotalcites produced by an aluminium hazardous waste: A comparison between the use of ammonia and the use of triethanolamine

“…Furthermore, a considerable number of investigations were reported in the literature based on a better control of the product uniformity and particle size which could result in being key factors for final uses and applications. These studies described variations in the synthesis process from the point of view of precursors and synthesis conditions, such as the production of hydrotalcites with microwaves (Rivera et al, 2006;Benito et al, 2008), sono-assisted preparations (Climent et al, 2004;Chang et al, 2011) or sol-gel methods (Lopez et al, 1996).…”