Equilibrium adsorption isotherms for methane, ethane, ethylene, acetylene, propane, and propylene have been measured for the first time on mesoporous silica, SBA-15, and the data are analyzed by using the Langmuir-Freundlich adsorption isotherm model. The adsorption capacities for ethylene and propylene are found to be higher than those for corresponding alkanes. Likewise, adsorption of acetylene is more pronounced as compared to ethylene. The isosteric heats of adsorption for various adsorbates estimated by the Clausius-Clapeyron equation are higher for olefins and acetylene and are comparable with those reported for π-complexation based systems. Such a trend has in turn suggested a higher affinity of SBA-15 framework for alkenes over corresponding alkanes, which has been examined in terms of the textural characteristics of SBA-15. It is suggested that SBA-15 can potentially be a good adsorbent for separation of light hydrocarbons.

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This paper reviews various synthetic protocols for poly‐α‐olefin (PAO) synthetic lubricant base stocks that have evolved over the years. Apart from conventional Lewis acid catalysts known for the synthesis of poly‐α‐olefins, such as aluminium trichloride and boron trifluoride, several new catalysts such as metallocenes and ionic liquids have been reported by various researchers. With increasing options of catalytic processes available, it is now possible to produce tailor made PAOs and thus control the properties of the end products, such as viscosity and the viscosity index. Although 1‐decene is the most widely used monomer for PAO application, researchers have used a wide range of monomers from 1‐hexene to 1‐tetradecene and internal olefins in some cases. Copyright © 2011 John Wiley & Sons, Ltd.