【作者】 唐雷；

【导师】 石秋杰；

【作者基本信息】 南昌大学 ， 物理化学， 2006， 硕士

【摘要】 本文以苯选择性加氢制环己烯为探针反应，考察了反应条件、稀土（Nd、Sm、Eu、Lu）和不同载体（海泡石、酸改性海泡石、离子交换海泡石、二氧化钛／酸改性海泡石复合载体，膨润土，三氧化二铝、二氧化钛／三氧化二铝复合载体）对Ru-B合金催化性能的影响。采用等离子体发射光谱（ICP）分析催化剂合金组成，N₂吸附法测定催化剂的比表面和孔径，程序升温还原法（TPR）研究催化剂的还原性能，氢气、环己烷、环己烯程序升温脱附法（H₂-TPD、Cyclohexane-TPD、Cyclohexene-TPD）研究催化剂的吸附性能。 结果表明，对于Ru-B／Sep（酸改性海泡石）催化的苯选择性加氢制环己烯反应体系，最佳反应条件为：起始反应温度393K，反应压力3.5MPa，水／苯体积比为1（各10ml），催化剂用量0.1g，反应时间20min，七水合硫酸锌的用量0.3克。 海泡石经酸改性后，催化剂的活性和选择性增大。这是由于海泡石经酸改性后，比表面积增大，有利于提高Ru的分散度；催化剂大孔比例增大，小孔比例减少，有利于环己烯的扩散，而且环己烯在Ru-B／Sep-10上更容易脱附，有利于提高选择性。海泡石经Zn²⁺、Fe³⁺交换后，催化剂的活性和选择性增大；而经Ti⁴⁺交换后，催化剂的活性增大，而选择性降低。这是由于，海泡石经离子交换后，组成和表面性质发生改变，使得Ru-B合金与载体的相互作用发生改变，从而影响了催化剂的催化性能。酸改性海泡石中引入适量的二氧化钛，能提高催化剂的活性，却降低了催化剂的选择性。这是由于适量的二氧化钛能增大催化剂的比表面积，有利于提高Ru的分散度；钌原子与TiO₂的强相互作用，从而使催化剂表面的氧化物种变得更易被还原；除了Ru-B／TiO₂-40％／Sep-10外，其余催化剂表面弱吸附中心的吸氢强度不变或变强，中、强吸附中心的吸氢强度变弱，有利于催化加氢反应的发生。引入二氧化钛，使催化剂的大孔比例减少，不利于环己烯的扩散，同时，二氧化钛使环己烯在催化剂上更难脱附，不利于提高环己烯的选择性。 在Ru-B／Bn、Ru-B／Al₂O₃中加入稀土，能不同程度的提高催化剂的活性和选择性。这是由于，加入稀土能提高催化剂的比表面积，有利于提高Ru的分散度。Ru-B／Bn和Ru-RE-B／Bn的TPR结果表明，稀土使得催化剂表面的Ru氧化态物种更多还原

【Abstract】 Bezene selective hydrogenation to cyclohexene was selected as the probe reaction to study the catalytic properties of supported amorphous Ru-B alloy catalyst. The effects of reaction conditions, rare earths （RE） and supports including sepiolite （Sep）, acid modified sepiolite（Sep-A）, ion exchanged sepiolite （Sep-I）, bentonite, A1₂O₃, TiO₂/Sep-A and TiO₂/Al₂O₃ composite supports on the catalytic properties of Ru-B alloy were studied. The Ru loading and composition of the alloys were analyzed by means of inductively coupled plasma optical emission spectroscopy （ICP）, special surface area and pore distribution of the catalysts were measured by nitrogen adsorption method. The surface properties of the catalysts were characterized by temperature programmed reduction （TPR） and temperature programmed desorption （TPD） of hydrogen, cyclohexane and cyclohexene, respectively.It is found that the optimal reaction conditions for the reaction catalyzed by Ru-B/Sep are as follows:initial reaction temperature 393K, hydrogen pressure 3.5MPa, water/benzene ratio 1:1, amount of catalyst 0.1g, reaction time 20 minutes, amount of ZnSO₄ ? 7H₂O 0.3g.Ru-B/Sep-A exhibits higher activity and selectivity than Ru-B/Sep. This is attribute to that the higher special surface area of Sep-A is in favor of well dispersion of Ru and that the lager pore diameter of Sep-A facilitates the diffusion of cyclohexene. Additionally, cyclohexene desorbs at lower temperature for Ru-B/Sep-A than that for Ru-B/Sep. Ion exchange can change the composition and surface properties of Sep, which affects the interaction between Ru-B alloy and supports. Therefore, the catalytic properties are changed. Ru-B/Sep-Zn and Ru-B/Sep-Fe exhibit higher activity and selectivity than Ru-B/Sep. Ru-B/Sep-Ti shows higher activity but lower selectivity. Proper amount of TiO₂ added to Sep-A by impregnation method can improve the activity but decrease the selectivity to cyclohexene. It can be explained by that proper amount of TiO₂ can improve special surface area of the catalysts, and that Ru⁶⁺ oxides on the surface of the catalysts reduced more easily owing to the更多还原