الفهرس 
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Abstract
Facile Synthesis and characterization of a Thermally Stable Modified- Alumina with Tunable Catalytic Activity.
Alumina-hollow-microspheres- Graphene oxide (GO) composites with hierarchical macromesoporous structure and controllable GO loadings from 2 to 20 wt.% had been synthesized using a self-limiting hydrogel method. The composite with 5wt.% GO loading exhibited the best catalytic activity in sunflower oil transesterification, giving an oil conversion of 85.2% by using only 1.0 wt. % catalyst to oil at 60°C in traditional batch reactor. Furthermore, the same composite (GO(5wt.%)-alumina) exhibited higher oil conversion (97%) to methyl esters in autoclave reactor at 120 °C. The significant high activity of this composite toward oil conversion was attributed to that its macroporous structure facilitated the diffusion of products, and it has higher amounts of both acidic and basic oxygen functional groups than either the neat GO or alumina. In addition, GO(5wt.%)-alumina composite, also showed good water tolerance, as the oil conversion was varied from ca. 85.2 to 79.2 % in 10 h when the water content in reaction mixture was increased from 0.0 to 3.0 wt.%. The stability of this composite in liquid water at 200°C for 12 h was also examined using variety of physicochemical techniques. It is shown that the presence of GO (5wt.%) inhibited the hydration of γ-alumina to form boehmite.
[Abstract]
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Keywords: hollow spheres, alumina, graphene oxide, hierarchically, macro-mesoporous, composite, biodies