Direct Correlation between Adsorption Energetics and Nuclear Spin Relaxation in a Liquid-saturated Catalyst Material

Area of Science:

• Catalysis
• Materials Science
• Physical Chemistry

Background:

• Mesoporous catalysts are crucial in chemical processes.
• Understanding adsorbate-surface interactions is key to catalyst design.
• Non-destructive methods for characterizing these interactions are highly valuable.

Purpose of the Study:

• To establish a quantitative relationship between NMR relaxation time constants and adsorption energetics.
• To demonstrate the utility of NMR relaxation for probing surface affinities in liquid-saturated mesoporous catalysts.
• To investigate the adsorption of primary alcohols and cyclohexane on a silica catalyst support.

Main Methods:

• Measurement of NMR relaxation time constants ($$) at intermediate magnetic field strength.
• Density Functional Theory (DFT) calculations of adsorption energies for single molecules on a silica surface.
• Comparison of experimental NMR data with theoretical DFT calculations.

Main Results:

• NMR relaxation measurements provide a non-destructive indication of relative surface affinities.
• A quantitative relationship between NMR relaxation and adsorption energetics was supported.
• $$ values correlated well with DFT adsorption energy calculations for model systems.

Conclusions:

• NMR relaxation is a powerful method for determining adsorption phenomena in mesoporous solids.
• This metric effectively quantifies surface affinities in liquid-phase heterogeneous catalysis.
• The findings have relevance for green chemical processes and catalyst development.