负载型镍基双金属非晶态合金催化剂的化学复合镀法制备及相关XAFS表征

The amorphous alloys have been received increasing attention and considered to be the promising catalysts for many kinds of catalytic reactions, because they possess distinct chemical and structural characters, such as short-range ordered and long-range disordered atomic arrangement, adjustable compositions, high homogeneity in structure, and high concentration of coordinatively unsaturated sites. In comparison with the unsupported Ni-based amorphous alloy catalysts (such as Ni-B and Ni-P), the supported Ni-based bimetallic amorphous alloy catalysts have drawn more and more attention because of their larger specific surface area, higher thermal stability, lower cost and superior catalytic properties in a variety of catalytic processes, especially in hydrogenation reactions. However, the traditional preparation (the impregnation-reduction method) and characterization (such as the XRD and SAED) methods have limited the development of the supported Ni-based bimetallic amorphous alloy catalysts. For the impregnation-reduction method, it is very difficult to ensure formation of only bimetallic particles. Formation of separate metallic particles of both metals often occurs. And it is more difficult to correlate catalyst performance with bimetallic catalyst composition. The detailed structural information and the structure-performance relationship could not be revealed by the XRD (X-ray diffraction) and SAED (Selected area electron diffraction) characterization results...In order to overcome the disadvantages of the traditional preparation and characterization methods, a novel method, electroless composite plating will be proposed and used to prepare the supported Ni-based bimetallic amorphous alloy catalysts. And the X-ray absorption fine structure (XAFS) will be adopted to characterize the catalysts. (1) Effects of the support activating processes, successive steps of metal plating, simultaneous plating of both metals, main factors affecting composite plating (temperature, pH, reductant, and complexing agent) on the plating results will be deeply studied. (2) The activated supports, intermediates, and the bimetallic amorphous alloys prepared at different conditions will be characterized by some modern analysis technologies, especially the XAFS, so as to gain a deep insight into the fine structure and the deposition mechanism of the bimetallic alloys. (3)The hydrogenation of sulfolene to sulfolane, hydrogenation of fructose to mannitol, and hydrogenation of dibenzo-18-crown-6 ether (DB18C6) to dicyclohexano-18-crown-6 ether (DCH18C6) will be used as the probe reactions for evaluation of the catalytic performances. (4) The structure and the surface properties of the fresh and used catalysts will be characterized by the XAFS, XRD, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), high resolution transmission electron microscopy(HRTEM), scanning electron microscope (SEM), inductively coupled plasma spectroscopy (ICP) and BET surface area measurement. Based on the characterization and activity test results, the preparation mechanism of the supported Ni-based bimetallic amorphous alloy catalysts will be discussed and the structure-activity relationship will be revealed. The above studies may promote the development of the supported amorphous alloy catalysts, which will be helpful for the design and fabrication of new amorphous alloys catalysts for hydrogenation in theory and experiment.

负载型镍基非晶态合金在诸多催化加氢反应中显示出优于目前大量使用且有许多缺点的骨架镍的催化性能，因而颇受青睐。然而传统的制备方法（如浸渍还原法）和表征方法（如XRD）由于自身的缺陷影响了对新型高性能非晶态合金催化剂设计制备、精细表征、构效规律的深入探究，制约了其在催化领域的应用。本课题从催化剂设计制备与精细表征入手，提出用化学复合镀法制备负载型镍基双金属（Ni-TM）非晶态合金催化剂，系统研究载体活化、双金属分镀、共镀、施镀参数对双金属化学镀效果的影响规律；利用XAFS等分析技术表征化学镀中间体、不同双金属分布（Ni包覆TM、TM包Ni、富Ni混合、富TM混合、Ni与TM均混）的催化剂精细结构, 揭示化学镀中双金属的沉积机理；选择环丁烯砜、果糖等加氢反应评价催化剂的加氢性能；探究催化剂的化学复合镀法制备—组成结构—催化性能之间的关联规律，为非晶态合金催化剂研究与开发提供理论与实践上的指导。

镍基硼型或磷型非晶态合金催化剂与传统骨架镍（Raney Ni）相比，不但具有成本低、抗毒能力强、制备过程环境污染少和空气中不易自燃等优点，而且已被证明在众多催化加氢反应中展现出更加优异的催化性能。然而负载型镍基非晶态合金传统制备方法（如浸渍还原法）和表征方法（如XRD）由于自身的缺陷影响了对新型高性能非晶态合金催化剂设计制备、精细表征、构效规律的深入探究，制约了其在催化领域的应用。. 本课题创造性地提出用化学复合镀法制备负载型镍基双金属（Ni-M）非晶态合金催化剂，并将X射线吸收精细结构引入对所制催化剂的表征。进行了如下几方面研究：1.化学镀制备Ni-M-B(P)/AC催化剂 (M=Pd、Ir、Ag、Ni、Fe；AC为活性碳)，研究了不同诱导金属、镍负载量及还原剂对所制催化剂的影响。2. 以Ir为活化诱导金属，采用化学复合镀法制备了NiMoP-1%Ir/AC和NiMoB-1%Ir/AC催化剂，研究了Mo添加量、反应时间等因素对所制催化剂的影响。3. NiCuB与NiCuB/AC的制备、表征及催化性能: 基于对镀液温度、NaOH浓度和铜镍摩尔比三个施镀参数的优化，获得了NiCuB的制备规律；在优选的化学镀参数下，制备不同NiCuB负载量的NiCuB/AC，并对催化剂进行了结构、组成及环丁烯砜催化加氢性能进行研究。4.Ni-M-B（M=Fe, Cu, Co)及负载型Ni-M-B（载体为AC及TiO2）化学镀法制备、表征及催化加氢性能研究，使用Ag，Fe, Cu, Co等不同诱导金属，采用化学镀法成功制备了Ni-M-B及负载型Ni-M-B催化剂，采用XRD、TEM、XAFS等表征了催化剂的非晶态合金结构；以环丁烯砜加氢和果糖加氢反应评价了催化剂的活性。研制出的新型镍基双金属非晶态合金催化剂如Ni-Cu-B及Ni-Fe-B在环丁烯砜加氢反应中表现出了优于Raney Ni的活性，有望成为新一代加氢催化剂。. 本项目基于诱导金属、还原剂、施镀参数对化学镀制备镍基非晶态合金催化剂影响实验及表征分析研究，获得了化学复合镀法制备负载型镍基双金属非晶态合金催化剂的制备规律，为设计开发新型负载型镍基非晶态合金催化剂提供理论和实验上的指导。