【作者】 王茂功；

【导师】 钟顺和；

【作者基本信息】 天津大学 ， 工业催化， 2007， 博士

【摘要】 采用表面改性和等体积浸渍法制备了Pd/VSiO和Pd/MgO/VSiO催化剂,采用BET、XRD、TEM、XPS、TPD、化学吸附-红外光谱（IR）和微反技术对催化剂的比表面积、晶相结构、价态、异丁烷的化学吸附性能和CO₂部分氧化异丁烷制异丁烯的催化性能进行了研究。结果表明:Pd/VSiO催化剂中的钒以V5+形式存在,在催化剂表面形成活性位V=O,其中V=O晶格氧与i-C4H10分子的-CH3和-CH中的H产生化学吸附作用;催化剂中金属Pd与V4+协同作用使CO₂在催化剂上产生了卧式吸附态;晶格氧参加了催化氧化反应,催化剂中V5+←→V4+变化构成了催化反应的氧化还原过程。向Pd/VSiO催化剂中引入碱性助剂MgO可以提高V2O5和金属Pd在载体SiO₂表面的分散度,MgO的供电子效应使催化剂表面V=O中晶格氧的电子云密度增大,i-C4H10分子-CH3和-CH中的H更易吸附在V=O中晶格氧上活化,从而提高i-C4H10转化率和i-C4H8的选择性。采用液态亚胺化法,利用4,4’-六氟亚异丙基-邻苯二甲酸酐、2,4,6-三甲基-1,3-苯二胺和3,5-二氨基苯甲酸合成了具有大量功能支链羧酸基的可溶性聚酰亚胺。通过溶胶-凝胶法将聚酰亚胺溶于溶剂中分别与不同量的SiO₂、TiO₂和SnO₂溶胶杂化,涂敷在以TiO₂为过渡层的硅藻土-莫来石陶瓷膜管支撑体上制备了不同无机氧化物含量的聚酰亚胺/SiO₂、聚酰亚胺/TiO₂和聚酰亚胺/SnO₂杂化膜反应器。采用FTIR、TG/DTA、DSC、SEM、TEM、XPS、BET和气体渗透测定对各膜反应器进行了表征和测试。结果表明:各个膜反应器的膜层成膜情况良好,层间结合紧密,顶层杂化膜具有良好的有机无机兼容性和热稳定性;杂化膜材料中聚酰亚胺亚胺化完全,聚酰亚胺高分子通过支链羧酸基与无机相（SiO₂、TiO₂和SnO₂）发生化学键连;聚酰亚胺高分子膜和含不同无机氧化物的杂化膜均对水蒸气和CO₂有较好的选择分离作用;聚酰亚胺/SnO₂杂化膜对CO也具有较好的分离作用,且随着SnO₂含量的增加分离效果增强。应用上述制备的三种膜反应器,以Pd/MgO/VSiO为催化剂,分别研究了CO₂部分氧化i-C4H10制i-C4H8的反应性能。在P=0.1Mpa、T=400℃、SV =1200 h-1、V （CO₂） / V （i-C4H10） =1和CO₂吹扫气流速为40ml/min的操作条件下,在三种膜反应器中催化反应分别取得了i-C4H10转化率9.32%、9.83%和10.45%以及i-C4H8选择性96.44%、96.78%和97.14%的优良结果,而在此条件下常规反应i-C4H10转化率和i-C4H8选择性却仅有7.54%和95.71%。更多还原

【Abstract】 In this paper, Pd/VSiO and Pd/MgO/VSiO catalysts were prepared by the methods of surface modification and incipient impregnation. Their structures, valence states, chemisorption properties of isobutane and carbon dioxide and catalytic behavior for isobutane partial oxidation with CO₂ were characterized by BET, XRD, TEM, XPS, TPD, IR and micro-reactor techniques. The results showed that the lattice oxygen of V=O is the active site on the Pd/VSO catalyst, and the valence of vanadium in the V=O is positive 5. Isobutane was chemisorbed on the lattice oxygen of V=O through the H atoms in -CH3 and–CH. and carbon dioxide was chemisorbed horizontally on the Pd metallic and V4+ through their synergetic effect. The V5+-V4+ couple plays a key role in the redox mechanism of the catalytic reaction. MgO introduced promoted the dispersion of V2O5 and Pd metallic on the surface of silica. The addition of MgO could improve conversation of i-C4H10 and selectivity of i-C4H8 because electrophobic effect of MgO to lattice oxygen of V=O could promote the chemisorption and activation of the H atoms in -CH3 and–CH.A new kind of soluble polyimide with plenty of carboxyl along the polyimide backbone was solution imidized employing 4, 4’-hexafluoroisopropylidenediphthalic anhydride, 2, 4, 6-trimethyl-1, 3-phenylenediamine and 3, 5-diaminobenzoic acid. The different kinds of membrane reactors of polyimide/-inorganic, SiO₂, TiO₂ and SnO₂ supported on TiO₂/kieselguhr-mullite were prepared. Their morphologies, chemical structures, thermal performances, pore distribution and gas permeability were characterized by methods of SEM, FTIR, XPS, TG/DTA, DSC, BET and gas permeability measurement. The results showed that the morphology of the supported membranes was quite homogeneous and the layers of each membrane were coupled tightly and naturally. The hybrid membranes possess higher thermal stability and compatibility between the organic and inorganic components. The hybrid membranes possess the space networks with regular pores formed by the connection between the polyimide and inorganic phases via the carboxyls along the polyimide backbone. The pure polyimide and each hybrid membrane showed separation properties for CO₂ and H2O. The polyimide-SnO₂ hybrid membranes have fine separation properties for CO, and the separation function was increased with the increasing of SnO₂ contents.The conversional catalytic reaction and membrane catalytic reaction for i-C4H10 partial oxidation with CO₂ were studied over Pd/MgO/VSiO catalyst in the polyimide-inorganic, SiO2, TiO2 and SnO2, hybrid membranes reactors. Under the conditions of 400°C, 0.1MPa, mixed gas space velocity of 1200h-1 and CO2 / i-C4H10 ratio of 1, the isobutane conversion of 9.32%, 9.83%, 10.45% and isobutene selectivity of 96.44%, 96.78%, 97.14% are achieved. However, under the same conditions, the isobutane conversion and isobutene selectivity of the conversional catalytic reaction were 7.54% and 95.71%, respectivly.更多还原