R J Taylor – författare

Research Paper (postgraduate) from the year 2015 in the subject Chemistry - Organic Chemistry, , language: English, abstract: The present study investigates the oxidative dehydrogenation of propane-butane (C3-C4) fraction over mono (Cr or Mo) and bi-metal (Cr-Mo) loaded SiO2 catalysts. The catalysts were prepared by sequential impregnation method at 500oC calcination temperature. Experiments were performed by feeding C3-C4 fraction, oxygen, nitrogen, and steam into a continuous flow quartz reactor at an atmospheric pressure (P = 1 atm.), reaction temperatures between 500 - 650oC, gas hourly space velocity (GHSV) within 100 - 400 h-1, and at reaction time (tr) = 2h. Appropriate water vapor addition to the feed sinificantly minimizes oxidation into coke deposits on the catalyst surface, and also prevents further olefin conversion into undesirable product. The physicochemical properties were evaluated by BET, XRD, IR, and EPR characterization techniques. The major oxidation products are ethylene, propylene, isobutylene, butylene. This paper reports that the total yield of olefins (? C2-C4) = 66.0 % was achieved at 83.5 % conversion level of C3-C4 at 630oC. The results indicate that the addition of Mo to catalysts of Cr/SiO2 modifies its catalytic activity for the ODH reaction. Mono-metallic catalysts (Cr/SiO2 and Mo/SiO2) were prepared for comparison purposes.

When assuming the task of preparing a book such as this, one inevitably wonders why anyone would want to read it. I have always sympathized with Charles Elton''s trenchant observation in his 1927 book that ''we have to face the fact that while ecological work is fascinating to do, it is unbearably dull to read about . . . '' And yet several good reasons do exist for producing a small volume on predation. The subject is interesting in its own right; no ecologist can deny that predation is one of the basic processes in the natural world. And the logical roots for much currently published reasoning about predation are remarkably well hidden; if one must do research on the subject, it helps not to be forced to start from first principles. A student facing predator-prey interactions for the first time is confronted with an amazingly diverse and sometimes inaccessible literature, with a ratio of wheat to chaff not exceeding 1: 5. A guide to the perplexed in this field does not exist at present, and I hope the book will serve that function. But apart from these more-or-Iess academic reasons for writing the book, I am forced to it by my conviction that predators are important in the ecological scheme. They playa critical role in the biological control of insects and other pests and are therefore of immediate economic concern.