Cobalt cerium oxides, prepared using a co-precipitation procedure, were studied as catalysts for the conversion of synthesis gas to light olefins (C 2 -C 4 ). Specifically, we studied the effect of a range of preparation variables, including the molar ratio of the [Co]/[Ce] of the precipitation solution, ageing time and calcination temperature. In addition, the effects of supports and promoters on the catalysts' activity and selectivity and a range of reaction temperatures using synthesis gas with different H 2 /CO molar feed ratios were investigated. The catalyst containing a molar ratio of 80% Co and 20% Ce, aged for 2 h, supported with 15 wt% SiO 2 without any promoter, at an operating temperature of 450 ºC and an H 2 /CO feed ratio of 2/1 (GHSV = 4500 h -1 ), performed optimally for the conversion of synthesis gas to light olefins. The characterization of both the precursors and the calcined catalysts by powder X-ray diffraction, scanning electron microscopy, Brunauer-Emmett-Teller specific surface area measurements and thermal analysis methods, including TGA and DSC, show that all the preparation variables influenced the catalyst precursor structure.

No abstract

Co–Ce catalysts prepared by the coprecipitation method were tested for production of light olefins. The effect of different preparation conditions including the [Co]/[Ce] molar ratio, aging time, calcination conditions, different supports, and loading of optimum support on the structure and catalytic performance of different catalysts were investigated. It was found that catalyst containing 80% Co/20% Ce/15% SiO2, which was aged for 2 h and calcined at 600°C for 6 h, is the optimum modified catalyst for the conversion of synthesis gas to light olefins. Characterization of both precursors and calcined catalysts (before and after the test) was carried out using scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) specific surface area measurements. The morphology of the catalysts was investigated by SEM and the surface areas of these catalysts were studied by BET. It was shown that all of the different preparation variables influenced the morphology and also the specific surface area of the catalyst precursors and calcined catalysts.

No abstract

The aim of this work is to develop a kinetic model for the oxidative coupling of methane (OCM) based on the gas‐hourly space velocity (GHSV) and methane‐to‐oxygen ratio. The experiments were carried out in a bench‐scale tubular‐fixed bed reactor, using 30 g of perovskite titanate as the reaction catalyst. Different GHSVs (3000–6000 h−1) and methane‐to‐oxygen ratios (2,2.5 and 3) were selected. A mechanism was assumed in which the consumption rate of methane is always twice the production rate of C2 hydrocarbons. A power‐law model was assumed for rate of reaction in terms of partial pressure of oxygen and methane. Using a linear regression analysis, the kinetic model was determined. Comparison of the calculated rate of reaction with the experimentally measured data confirmed the accuracy and applicability of the developed model under various reaction conditions. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd.

Synthesis of Highly Functionalized Annulated 4H-Pyrans. -The procedure offers a mild and facile approach to highly functionalized pyranopyrans and pyranochromenes. -(TEIMOURI*, M. B.; BAZHRANG, R.; ESLAMIMANESH, V.; NOURI, A.; Tetrahedron 62 (2006) 13, 3016-3020; Dep. Petrochem., Iran Polym. Petrochem. Inst., Tehran, Iran; Eng.) -Jannicke 30-147

No abstract