We report the first catalytic application of pore-expanded KIT-6 propylsulfonic acid (PrSO3H) silicas, in fatty acid esterification with methanol under mild conditions. As-synthesized PrSO3H-KIT-6 exhibits a 40 and 70% enhancement in turnover frequency (TOF) toward propanoic and hexanoic acid esterification, respectively, over a PrSO3H-SBA-15 analogue of similar 5 nm pore diameter, reflecting the improved mesopore interconnectivity of KIT-6 over SBA-15. However, pore accessibility becomes rate-limiting in the esterification of longer chain lauric and palmitic acids over both solid acid catalysts. This problem can be overcome via hydrothermal aging protocols which permit expansion of the KIT-6 mesopore to 7 nm, thereby doubling the TOF for lauric and palmitic acid esterification over that achievable with PrSO3H-SBA-15.

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By means of a true sensitivity enhancement for a solid-state NMR spectroscopy (SSNMR) experiment performed under dynamic nuclear polarization (DNP) conditions, corresponding to 4-5 orders of magnitude of time savings compared with a conventional SSNMR experiment, it is shown that it is possible to record interface-selective (27)Al-(27)Al two-dimensional dipolar correlation spectra on mesoporous alumina, an advanced material with potential industrial applications. The low efficiency of cross-polarization and dipolar recoupling for quadrupolar nuclei is completely negated using this technique. The important presence of pentacoordinated Al has not only been observed, but its role in bridging interfacial tetra- and hexacoordinated Al has been determined. Such structural information, collected at low temperature (∼103 K) and 9.4 T with the use of DNP, would have been impossible to obtain under standard conditions, even using a higher magnetic field. However, here it is demonstrated that this information can be obtained in only 4 h. This work clearly opens a new avenue for the application of SSNMR to quadrupolar nuclei and notably the atomic-scale structure determination of catalysis materials such as mesoporous alumina.