Kim Yongwoo, Kim Jonghyun, Kim Do Heui
School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University 1 Gwanak-ro, Gwanak-gu Seoul 151-742 Korea
RSC Adv. 2018 Jan 10;8(5):2441-2448. doi: 10.1039/c7ra13150j. eCollection 2018 Jan 9.
In this present work, we studied the effects of preparation methods and Ni/Pd ratios on the catalytic activity of a Ni-promoted Pd/C catalyst for the formic acid dehydrogenation (FAD) reaction. Two catalysts prepared by co-impregnation and sequential impregnation methods showed completely different Pd states and catalytic activities. As the sequentially impregnated catalyst showed better activity than the co-impregnated catalyst, the sequentially impregnated catalyst was investigated further to optimize the ratio of Ni/Pd. The highest catalytic activity for the FAD reaction was obtained over the seq-impregnated catalyst having a 1 : 1.3 molar ratio of Pd : Ni. The results of X-ray diffraction (XRD) and transmission electron microscopy (TEM) showed that small particle size is one factor improving the catalytic activity, while those of X-ray photoelectron spectroscopy (XPS) and X-ray adsorption near edge structure (XANES) indicate that the electronic modification of Pd to a positively charged ion is another factor. Thus, it can be concluded that the enhanced catalytic activity of the Ni-promoted Pd/C catalyst is attributed to the role of pre-impregnated Ni in facilitating the activity of Pd by constraining the particle growth and withdrawing an electron from Pd.
在本研究中，我们考察了制备方法和镍/钯比例对镍促进的钯/碳催化剂催化甲酸脱氢（FAD）反应活性的影响。通过共浸渍法和顺序浸渍法制备的两种催化剂呈现出完全不同的钯状态和催化活性。由于顺序浸渍法制备的催化剂表现出比共浸渍法制备的催化剂更好的活性，因此对顺序浸渍法制备的催化剂进行了进一步研究以优化镍/钯比例。在钯与镍摩尔比为1:1.3的顺序浸渍法制备的催化剂上获得了最高的甲酸脱氢反应催化活性。X射线衍射（XRD）和透射电子显微镜（TEM）结果表明，小粒径是提高催化活性的一个因素，而X射线光电子能谱（XPS）和X射线吸收近边结构（XANES）结果表明，钯向带正电离子的电子修饰是另一个因素。因此，可以得出结论，镍促进的钯/碳催化剂催化活性的提高归因于预浸渍镍通过限制颗粒生长和从钯中夺取电子来促进钯活性的作用。
