新型固定床Raney Ni制备过程中晶相结构的转化

以拟薄水铝石制备粘结剂，加入镍铝合金粉和田菁粉捏合、成型，在空气中高温焙烧，然后用苛性碱溶液充分浸取，制备出可应用于固定床加氢的活性Raney Ni催化剂。采用XRD和TG-DTA分析了催化剂制备过程中晶相结构的转化，结果表明，成型合金焙烧过程中，富铝合金相（如Al₃Ni-Al和Al₃Ni）逐渐转变为贫铝合金相（如Al₃Ni₂和AlNi），释放出的金属铝依次发生氧化，同时抑制金属镍的氧化；在高于1 123～1 133K焙烧时金属铝氧化生成α-Al₂O₃，使催化剂获得较高的颗粒强度。苯加氢活性评价结果表明，该新型固定床Raney Ni催化剂活性高于负载型镍催化剂，也高于参照专利方法制备的有机聚合物粘结的同类型催化剂，并且具有较好的低温加氢活性。

Crystal Phase Transformation during Preparation of Novel Fixed-bed Raney Nickel Catalysts

Novel Fixed-bed Raney nickel catalyst for hydrogenation of unsaturated org anic compounds has been prepared by extruding the Ni-Al alloy powder with pseudo boehmite, calcining the extrudates in air at higher temperature and leaching out the aluminum with caustic solution. XRD and TG-DTA analyses were used to charac terize the crystal phase transformation during the preparation of such catalyst. The experimental results show that during calcination procedures alloy phases r ich in aluminum (such as Al3Ni-Al or Al3Ni) will transform to ones poor in alumi num (such as Al3Ni2 or AlNi), and that aluminum released will be gradually oxidi zed to inhibit the oxidation of nickel. Such phase transformation will be accele rated over 1 123~1 133 K, and Al3Ni phase disappears and transforms to Al3Ni2 co mpletely and aluminum is oxidized to certain amount of alumina supported nickel catalyst and the same type of fi xed-bed Raney nickel catalyst prepared according to the patent methods.