A continuous gas flow MAS NMR probe for operando studies of hydrocarbon conversion on heterogeneous catalysts

A continuous gas flow magic angle spinning (MAS) NMR probehead has been developed, which enables simultaneously the observation of catalytic events occurring on catalyst surfaces and the on-line identification of the gas products in the output using mass spectrometry. The temperature inside the MAS rotor in the probe has been controlled and measured by 207 Pb MAS NMR spectroscopy of Pb(NO 3 ) 2 . The hydrogenation of toluene to methylcyclohexane on Pt/ZrO 2 –SO 4 (sulfated zirconia) has been used to demonstrate the ability of this probe to study heterogeneous reaction in situ in flow conditions ( operando ). The MAS NMR and mass spectrometry were in good qualitative agreement for the analysis of the reaction products. The reaction performed in parallel under similar conditions on a conventional fixed bed catalytic reactor shows that the reactant diffusion and their interaction with the active sites in the MAS NMR reactor are comparable in both conventional and NMR experiments. .