Surface Composition and Diffusion in Catalysts Probed by PFG NMR Techniques

D. Weber; M.D. Mantle; A.J. Sederman; L.F. Gladden

doi:10.4028/www.scientific.net/DDF.283-286.190

Paper Titles

Effects of Copper Powder Insert Layer on the Properties of Friction Welded Joints Between AlCu and AISI 4140 Structural Steel
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An Analytical Study on the Spherical Spindle of an Ultra Precision Machine for Use in Nano Machining Technology
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The Influence of External Load and Air Pressure on Air Slide Table Performance of Ultra Precision Machines in Nano Machining
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Experimental and Numerical Analysis of the Nickel Deposition and Diffusion Using Plasma in a Confined Anode-Cathode Configuration
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Surface Composition and Diffusion in Catalysts Probed by PFG NMR Techniques
p.190

High Temperature Oxidation of Liquid Cu-Ti Alloy at 1473K
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Diffusion Process of ⁸Li for Radioactive Beam Production
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Air Oxidation Kinetics Study of Zr₅₈Nb₃Cu₁₆Ni₁₃Al₁₀ Bulk Metallic Glass
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Evaluation of Concentration Dependent Diffusivities of Manganese in the Diffusion Joint Fe/FeMn-Steel by Means of Mathematical-Analytical Methods
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Surface Composition and Diffusion in Catalysts Probed by PFG NMR Techniques

Abstract:

We have recently developed an experimental protocol to study surface self-diffusion using Pulsed Field Gradient (PFG) Nuclear Magnetic Resonance (NMR) techniques. While the study of diffusion phenomena with PFG NMR techniques evolved in the 1960s and is nowadays part of the standard NMR toolbox, our novel approach allows us the simultaneous quantification of diffusion coefficients of molecules in a surface layer and the bulk pore liquid of a porous medium. This is of relevance when attempting to explain solvent effects in catalysis. Solvent effects are known to have a significant impact on catalyst performance. For example, water has been reported to influence the reaction rates during carbonyl hydrogenations. In this work we have assessed the effect of two solvents – water and isopropyl alcohol (IPA) - on the bulk pore and surface diffusivity of methyl ethyl ketone (MEK) in porous Ru/SiO2 catalyst pellets. We find that when MEK is dissolved in water, it appears to interact more closely with the surface than when it is dissolved in IPA.