Wojcieszak R, Zieliński M, Monteverdi S, Bettahar M M
Catalyse Hétérogène, UMR 7565, Faculté des Sciences, Université Henri Poincaré, Nancy-I, BP 239, 54506 Vandoeuvre-lès-Nancy Cedex, France.
J Colloid Interface Sci. 2006 Jul 1;299(1):238-48. doi: 10.1016/j.jcis.2006.01.067. Epub 2006 Mar 24.
Nickel nanoparticles were obtained by the reduction in hydrazine aqueous media of nickel acetate as a precursor supported on activated carbon of high surface area. Classical catalysts using nickel acetate or nitrate were prepared for comparison. The catalysts were characterized by N(2) physisorption, H(2)-TPR, H(2)-adsorption, TPD, TEM, and XRD, and tested in the gas phase hydrogenation of benzene. Hydrazine catalysts were found much more active in benzene hydrogenation than corresponding classically prepared catalysts. Remarkably, their reactivity is comparable (turn-over frequency of 0.2001-0.2539 s(-1) at 393 K) to that of Pt classical catalysts supported on activated carbon in the same conditions. Evidence is given for the existence of the hydrogen spillover effect in benzene hydrogenation, not reported before in the literature. As a result of the hydrogen spillover effect, catalysts performances can be explained by a combination of surface metal atom reactivity, metal-support interaction strength, and specific surface area extent. Maximum effect is observed with hydrazine preparation method, for 1% Ni content and nickel acetate as a precursor. Unexpectedly, it was also found that hydrazine preparation increases the specific area of the catalysts.
通过在水合肼介质中还原负载在高比表面积活性炭上的醋酸镍前驱体来制备镍纳米颗粒。制备了使用醋酸镍或硝酸镍的传统催化剂用于比较。通过N₂物理吸附、H₂-TPR、H₂吸附、TPD、TEM和XRD对催化剂进行了表征，并在苯的气相氢化反应中进行了测试。发现肼催化剂在苯氢化反应中比相应的传统制备催化剂活性高得多。值得注意的是，在相同条件下，它们的反应活性（393K时的周转频率为0.2001-0.2539 s⁻¹）与负载在活性炭上的Pt传统催化剂相当。文中给出了苯氢化反应中存在氢溢流效应的证据，这在之前的文献中未曾报道过。由于氢溢流效应，催化剂的性能可以通过表面金属原子反应性、金属-载体相互作用强度和比表面积大小的综合作用来解释。对于1%的镍含量和以醋酸镍为前驱体，采用肼制备方法时观察到最大效应。出乎意料的是，还发现肼制备方法增加了催化剂的比表面积。
