【作者】 关业军；

【导师】 李灿；

【作者基本信息】 中国科学院研究生院（大连化学物理研究所） ， 物理化学， 2007， 博士

【摘要】 随着环境污染问题的日益严峻,氯代芳烃及二恶英等高毒性有机污染物的排放控制和消除引起了学术界、工业界、政府和公众的普遍关注。低温吸附或低温催化氧化能够实现二恶英的零排放。本论文详细考察了二苯并二恶英（DD）在氧化物上的吸附行为,并以形成二恶英的可能前体氯苯为模型化合物,研究了CeO₂及VOx/CeO₂催化剂上氯苯的催化氧化性能。利用红外光谱技术和差热分析方法研究了DD在氧化物和分子筛上的吸附与脱附行为。结果表明,DD与氧化物分别存在三种不同强度的相互作用模式,分子筛孔道对DD电子结构的限制作用>表面Lewis酸中心的电子配位作用>表面羟基的氢键作用。DD在各种氧化物上的脱附温度高低顺序为:NaY、丝光沸石> H-ZSM-5、Na-ZSM-5 >无定形氧化物（SiO₂、Al₂O₃、TiO₂及SBA-15）。研究了采用不同沉淀剂制备的CeO₂及VOx/CeO₂催化剂上氯苯的催化氧化性能。结果表明,所用催化剂均表现出较高的氯苯催化氧化活性。尿素为沉淀剂制备的催化剂（CeO₂-U）上的氯苯催化氧化活性高于Na2CO3和NH3-H2O₂沉淀剂制备的CeO₂。在考察的催化剂中,VOx/CeO₂-U显示了最高的氯苯催化氧化活性,在250 oC下,可将空速为10000 ml·g^-1·h^-1空气中1000 ppm的氯苯完全氧化。表征结果表明CeO₂-U表面的（110）和（100）等高活性晶面有利于氧化钒与氧化铈形成高活性V-O-Ce物种。研究还发现,Na+和水汽的存在会导致负载氧化钒中毒。本论文还研究了乙醇在Au/CeO₂及Au/SiO₂等催化剂上的催化转化。结果表明催化剂表面的金纳米粒子和Au3+都具有较好的乙醇选择氧化活性。无氧条件下,乙醇在金催化剂上的脱氢反应活性与金纳米粒子大小相关,小于6 nm的金纳米粒子活性明显高于大尺寸的金纳米粒子。在400 oC时,脱氢反应的乙醛单程收率高达76%。更多还原

【Abstract】 The emission abatement of toxic chemicals, such as chlorinated aromatics and polychlorinated dioxins/furans （PCDD/F） has attracted much attention from academia, industry, government and public with the growing environmental crisis. Adsorption or catalytic oxidation of dioxin-like compounds at low temperatures is a useful strategy for the emission abatement of dioxins. In this thesis work, the adsorption/desorption behaviors of dibenzodioxin on inorganic materials have been studied. The catalytic oxidation of chlorobenzene, the possible precursors of dioxins formation, on CeO₂ and VOx/CeO₂ catalysts has been investigated.Dibenzodioxin adsorption/desorption behaviors on inorganic materials （amorphous/mesoporous silica, metal oxides, and zeolites） were investigated using in situ FT-IR spectroscopy and thermogravimetric （TG） analysis. It is proposed that the dibenzodioxin adsorption is mainly via the following three interactions: hydrogen bonding with the surface hydroxyl groups on amorphous/mesoporous silica, complexation with Lewis acid sites on metal oxides, and confinement effect of pores of mordenite and NaY with pore size close to the molecular size of dibenzodioxin. The order of dibenzodioxin desorption temperature is following: mordenite and NaY > H-ZSM-5 and Na-ZSM-5 > amorphous/mesoporous silica.A series of CeO₂ prepared via precipitation with different precipitation reagents have been used as the catalyst and catalyst support for the total oxidation of chlorobenzene. The cerium oxides and supported VOx catalysts were characterized by X-ray diffraction （XRD）, temperature programmed reduction （TPR）, and Raman spectroscopy. All catalysts show quite high catalytic activityfor chlorobenzene oxidation. CeO₂ catalyst prepared with urea （named as CeO₂-U） shows higher activity than those prepared with Na2CO3 and NH3-H2O₂. VOx/CeO₂-U catalyst shows the highest activity among all catalysts investigated. A total oxidation of 1000 ppm chlorobenzene on VOx/CeO₂-U can be achieved at 250 oC with space velocity of 10000 ml·g^-1·h^-1. It is proposed that the reactive crystal planes on the surface of CeO₂-U like （110） and （100） benefit to the formation of highly reactive surface V-O-Ce species. The presence of Na+ or water vapor results in the deactivation of vanadium oxide catalyst.The ethanol conversion on Au/CeO₂ and Au/SiO₂ catalysts was also investigated. It was found that both Au nanoclusters and Au3+ species are reactive for the selective oxidation of ethanol to acetaldehyde. For ethanol dehydrogenation in the absence of O₂, a significant particle size dependence effect was observed: Au nanoparticles with size below 6 nm show much higher catalytic activity than those with bigger Au particles. The yield of acetaldehyde from ethanol dehydrogenation at 400 oC is 76% on Au nanoparticles with the mean size of 5 nm.更多还原