Novel catalysts of phosphotungstic heteropolyacids(PW_(12))supported on neutral alumina were prepared by assistance of ultrasound and plasma treatment.The prepared catalysts were characterized by FT-IR pyridine adsorption(Py-IR),temperature programmed desorption of Pyridine(Py-TPD),BET and X-ray diffraction(XRD),and their catalytic performances were evaluated by the cationic polymerization of tetrahydrofuran.The results indicate that plasma treatment remarkably increases the surface acidity of the prepared catalyst while ultrasonic treatment induces PW_(12)to uniformly disperse on the support surface and expose more active sites for the acid catalytic reaction.A higher catalytic activity(69.7%)is obtained on the novel catalyst,which significantly outstripped that on the conventional sample(57.5%).
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机译:How the Group Leaders of Lesson Preparation Groups Facilitate Group Learning and Reflective Practice in Chinese Public High Schools =中国公立高中的备课组长是如何引领团队学习和反思性实践的?