Tuning the acidic properties of aluminas via sol-gel synthesis: New findings on the active site of alumina-catalyzed epoxidation with hydrogen peroxide

Synthesis of high-surface-area γ-Al2O3 from aluminum scrap and its use for the adsorption of metals: Pb(II), Cd(II) and Zn(II)

“…These polymer chains are later transformed at very high temperature into aluminum oxides of various structures. These processes have been studied and detailed information is available in the literature [8,11]. Thus, we firstly characterized the polymer gel produced by the reaction of sodium aluminate with sulfuric acid.…”

“…According to the literature [6,8,12], among the many polymeric species, the commonest are: Al 13 12 ] 7+ . These species are formed initially by oxolation and oleation processes, followed by polymerization of aluminum hydroxide molecules, and, finally by nucleation and growth processes, resulting in the formation of particles of hydrated alumina [8,11]. The terms oxolation and oleation refer to the formation of Al O Al bonds and Al OH groups, respectively, during the polymerization of aluminum hydroxide molecules.…”

Hierarchical Zeolites and their Catalytic Performance in Selective Oxidative Processes

“…[30] The authors related this unusual epoxidation activity in USY to the formation of surface hydroperoxide species (AlÀ OOH) from the reaction of AlÀOH groups with hydrogen peroxide as previously reported for Al 2 O 3 . [31] The development of mesoporosity in hierarchical zeolites can open up the porous framework in these materials, and induce the formation of a large number of accessible terminal AlÀOH groups. [3] Liu et al [32] recently reported the catalytic performance of alkali-treated ZSM-5 zeolite in the selective oxidation of benzylalcohol with hydrogen peroxide, pointing out that the reaction mechanism involves the formation of AlÀ OOH groups by direct reaction of AlÀOH sites with H 2 O 2 .…”

Adsorption of fluoride onto different types of aluminas

“…Previous studies show that acidity/basicity of alumina affect the adsorption capacity and catalytic properties of catalyzer [26,27]. Alumina with different basicity has different surface density of hydroxyl groups which play an important role in catalysis [27,28]. It is indicated that the adsorption capacity and activity of hydroxyl group was affected by the surface acidity/basicity of alumina.…”

“…Aluminas prepared at different pH and calcination temperatures have different chemical composition and surface properties [22][23][24]. In the catalytic field, the studies about alumina with different phases are well conducted [25][26][27][28]. Previous studies show that acidity/basicity of alumina affect the adsorption capacity and catalytic properties of catalyzer [26,27].…”