Institute of Physical Chemistry, University of Stuttgart, D-70569 Stuttgart, Germany.
Chem Soc Rev. 2014 Dec 21;43(24):8226-39. doi: 10.1039/c4cs00210e. Epub 2014 Oct 14.
The large majority of chemical compounds underwent at least one catalytic step during synthesis. While it is common knowledge that catalysts enhance reaction rates by lowering the activation energy it is often obscure how catalysts achieve this. This tutorial review explains some fundamental principles of catalysis and how the mechanisms are studied. The dissociation of formic acid into H2 and CO2 serves to demonstrate how a water molecule can open a new reaction path at lower energy, how immersion in liquid water can influence the charge distribution and energetics, and how catalysis at metal surfaces differs from that in the gas phase. The reversibility of catalytic reactions, the influence of an adsorption pre-equilibrium and the compensating effects of adsorption entropy and enthalpy on the Arrhenius parameters are discussed. It is shown that flexibility around the catalytic centre and residual substrate dynamics on the surface affect these parameters. Sabatier's principle of optimum substrate adsorption, shape selectivity in the pores of molecular sieves and the polarisation effect at the metal-support interface are explained. Finally, it is shown that the application of a bias voltage in electrochemistry offers an additional parameter to promote or inhibit a reaction.
绝大多数化学化合物在合成过程中至少经历了一个催化步骤。虽然催化剂通过降低活化能来提高反应速率是众所周知的，但催化剂如何实现这一点往往不清楚。本教程综述解释了一些催化的基本原理以及如何研究这些机制。甲酸分解为 H2 和 CO2 证明了水分子如何在较低能量下开辟新的反应途径，水的浸润如何影响电荷分布和能量学，以及金属表面的催化与气相中的催化有何不同。讨论了催化反应的可逆性、吸附平衡的影响以及吸附熵和焓对 Arrhenius 参数的补偿效应。结果表明，催化中心的灵活性和表面上残留的底物动力学会影响这些参数。解释了 Sabatier 最佳底物吸附原理、分子筛孔中的形状选择性以及金属-载体界面的极化效应。最后，结果表明，在电化学中施加偏置电压提供了一个额外的参数来促进或抑制反应。
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