【作者】 石秋杰；

【导师】 李凤仪； 罗来涛；

【作者基本信息】 华南理工大学 ， 工业催化， 1998， 博士

【摘要】 本文采用化学还原法制备了非晶态NiB及NiBRE合金催化剂，采用化学还原法与机械混合或与浸渍相结合的方法制备了固定化NiB及NiBRE合金催化剂．运用脉冲微反和连续微反技术以苯乙烯加氢、苯加氢、乙炔选择性加氢和二氧化碳甲烷化反应为探针反应首次系统地考察了14种稀土离子和5种不同的载体对非晶态NiB合金催化剂的加氢反应活性及稳定性的影响，同时也考察了还原剂浓度、热处理温度、氧化还原等对非晶态NiB合金催化剂性能的影响。用脉冲二硫化碳中毒法测定了催化剂的抗硫性．采用XRD、ICP、DSC、TEM、CO化学吸附法、TPR、TPD、TPSR、XPS等技术研究了改性前后NiB合金的体相及表面性质如结构、组成、热稳定性、粒子大小和形态、活性镍表面积、还原性能、吸附性能、表面酸性、活性中心类型及性质、表面组成和电子状态等．采用TG方法进行分析研究NiB合金催化乙炔选择性加氢反应迅速失活的原因，及稀土和载体对NiB合金抗积炭性能的影响．应用酸改性载体海泡石，用N₂吸附法测定了酸改性对其比表面和孔径分布的影响，并将它们与活性关联，得到了一些有意义的结论．本文还首次进行了非晶态NiB合金催化苯加氢脉冲反应动力学的研究，提出了活化能的求取方法，并推测了该类催化剂上气相苯加氢反应机理．研究结果表明当还原剂硼氢化钾浓度为3.0M、热处理温度为493K时NiB合金呈现最佳活性；稀土和载体对NiB合金具有明显的改性作用，增强了它的催化加氢活性、稳定性和抗硫性．稀土和载体对非晶态NiB合金的影响既存在结构效应又存在电子效应．它们增加了Ni上的电子密度和分散度，使得NiB合金表面存在的氧化镍易被还原、而Ni-B-O物种不易被还原，同时也改变了NiB合金对反应物氢的吸附强度。由于存在稀土或载体与Ni合金间的相互作用降低了反应的活化能。在非晶态NiB合金表面存在三种氢吸附中心，中、高温吸附中心为反应的活性中心。非晶态合金催化剂催化的气相苯加氢反应遵循Langmuir-Hinshwood机理，反应的活性中心座数为2，反应为双中心机理．稀土和载体加入后不改变活性中心座数。比较制备固定化合金催化剂的两种方法可知浸渍还原法优于机械混合法。更多还原

【Abstract】 Amorphous NiB and NiBSm alloys have been prepared by chemical reduction method and the fixed alloys prepared by chemical reduction method combined with mechanically mixing or with impregnation for the first time. The hydrogenation of styrene, benzene, ethyne and carbon dioxide are selected as probe reaction. The techniques of pulse and continuousmicroreaction are applied to study the effect of the concentration of the reductant KBH₄, pretreatment in N₂, fifteen rare earth elements and four supports on the catalyticactivities and stabilities of NiB alloy for series hydrogenation. The sulfur resistance character is determined by pulse CS₂ poisoning method. The bulk structure and composition of the alloys are examined by XRD and ICP, respectively. The thermal stablity of the samples is studied by DSC. The morphology of the alloy particles is observed by TEM and the disperse of them are determined by CO chemical absorption method. TPR. TPD. TPSR. XPS and so on have been used to charaterize the surface properties of the alloys such as reduction, absorbing, the types and character of the active sites over the surface of the samples, surface composition and electron state. TG is used to research the reason for rapidlydeactivation for ethyne hydrogenation over the alloys catalysts and to study the effect of rare earth and support on the number of carbon deposition as well. Sepoite, as a new kind of support, has been modified by acid. The effects of acid modification on the specific surface area and the distribution of the pore radius of sepoite are examined by N₂ absorption methos. Dynamic studies on the pulse reaction for benzene更多还原