Exact stoichiometry high surface area mesoporous AlPO₄ glass for efficient catalysis

Mesoporous AlPO₄ materials have attracted much attention in catalysis due to their high thermal and chemical stability. Of particular interest for catalysis is the pure stoichiometry high surface area (> 500 m²/g) mesoporous AlPO₄ (mAlPO₄) glass prepared via a template-free aqueous sol–gel synthetic route. Toward the application of this material for catalysis, we have developed methods for loading it with nanoparticles (NPs) of catalytic metals—Pd and Rh—and carried out a detailed characterization study of the resulting doped materials by a wide array of analytical methods, including synchrotron X-ray absorption spectroscopy, inelastic neutron scattering and more. The applicability of this material for catalysis, both by itself and as a support for catalytic NPs, was then evaluated. The pure mAlPO₄ exhibited excellent acid-catalyzed [3 + 2] cycloaddition of nitriles and sodium azide. mAlPO₄ loaded with the Pd NPs catalyzed very efficiently deoxygenation reactions of benzyl alcohols. mAlPO₄ loaded with Rh NPs catalyzed with high selectivity, the hydrogenation of phenols and cresols and full conversion the hydrogenation of the industrially very high-volume toluene to methylcyclohexane. The materials-science aspects of these successful catalysts were studied in detail, leading, for instance, to the understanding of the important role of the interfacial Rh/Pd–O-P bonds. Graphical abstract: [Figure not available: see fulltext.]