Robinson Neil, Robertson Christopher, Gladden Lynn F, Jenkins Stephen J, D'Agostino Carmine
Department of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge, CB3 0AS, United Kingdom.
Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, United Kingdom.
Chemphyschem. 2018 Oct 5;19(19):2472-2479. doi: 10.1002/cphc.201800513. Epub 2018 Jul 10.
The ratio of NMR relaxation time constants provides a non-destructive indication of the relative surface affinities exhibited by adsorbates within liquid-saturated mesoporous catalysts. In the present work we provide supporting evidence for the existence of a quantitative relationship between such measurements and adsorption energetics. As a prototypical example with relevance to green chemical processes we examine and contrast the relaxation characteristics of primary alcohols and cyclohexane within an industrial silica catalyst support. values obtained at intermediate magnetic field strength are in good agreement with DFT adsorption energy calculations performed on single molecules interacting with an idealised silica surface. Our results demonstrate the remarkable ability of this metric to quantify surface affinities within systems of relevance to liquid-phase heterogeneous catalysis, and highlight NMR relaxation as a powerful method for the determination of adsorption phenomena within mesoporous solids.
核磁共振弛豫时间常数的比值为液体饱和介孔催化剂中吸附质所表现出的相对表面亲和力提供了一种无损指示。在本工作中，我们为这类测量与吸附能之间存在定量关系提供了支持性证据。作为与绿色化学过程相关的一个典型例子，我们研究并对比了工业二氧化硅催化剂载体中伯醇和环己烷的弛豫特性。在中等磁场强度下获得的值与对与理想化二氧化硅表面相互作用的单分子进行密度泛函理论（DFT）吸附能计算的结果高度吻合。我们的结果证明了该指标在量化与液 - 相多相催化相关体系中的表面亲和力方面具有显著能力，并突出了核磁共振弛豫作为一种测定介孔固体中吸附现象的强大方法。
