Surfactants from biomass: a two-step cascade reaction for the synthesis of sorbitol fatty acid esters using solid acid catalysts.

Sorbitol fatty esters have been prepared through a two-step catalytic process which involves the protection of the polyalcohol by ketalization followed by esterification with the fatty acid. Inorganic molecular sieves with different pore topologies as well as heteropolyacids (HPA) were used as acid catalysts to perform both the ketalization and the esterification step. These catalysts are found to hydrolyze the ketal function and promote the esterification between the free hydroxy groups and oleic acid in a cascade process. The results show a positive shape-selectivity effect when the process is carried out using tridirectional, and especially monodirectional (mordenite), zeolites, such that the ratio of mono- to higher esters and the hydroxy number of the final product are increased as compared to those obtained for the homogeneous-catalyzed process.

A novel catalyst for synthesis of styrene: carbon nanofibers immobilized on activated carbon.

Carbon NanoFibers (CNFs) with hierarchically structure have been immobilized onto Activated Carbon (AC) by impregnation with an aqueous solution of Fe(CH3COO)2, reduction and subsequent chemical vapor decomposition of ethylene. The morphology of the CNFs can be modulated by adjusting the pH of the Fe(CH3COO)2 solution used for impregnating the AC. A stable yield of 35% in the oxidative dehydrogenation of ethylbenzene to styrene was obtained at a temperature of 673 K, around 200 K lower than the current industrial process. The immobilized CNFs on AC catalysts combine the catalytic properties of the carbon nanofibers and the suprastructure of the AC host. The final material is an easy to handle active catalyst, with an open structure of immobilized CNFs avoiding the pressure drop problem, which is typically observed for fine powder forms of CNFs. The immobilized CNFs on AC are attractive for gas-phase fixed-bed industrial applications.