In this article, a significant aspect of Brønsted groups in the preparation of HPA/Al-SBA-15 catalyst by immobilising heteropoly acid H3PW12O40 (HPA) to mesoporous Al-SBA-15 support was studied. The crucial factors affected the preparation such as functional groups formed on the support, the use of HPA type for the immobilisation (commercial catalyst or in-situ synthetic HPA), and Si/Al molar ratio of Al-SBA-15 were systematically investigated. The prepared catalysts were tested their performance in polar reagent reactions (fructone synthesis was chosen as an example) to show the effect of HPA after the immobilisaton. Here we tested the HPA content (by Energy-dispersive X-ray method), 2 acidity (by temperature-programmed desorption of ammonia method) and the ethyl acetoacetate conversion in fructone synthesis to prove this concept. The other characterisation methods such as small angle x-ray scattering, Fourier-transform infrared spectroscopy, specific surface area and pore volume also showed the properties change of materials before and after HPA immobilisation. It was shown that the HPA/Al-SBA-15 sample prepared by using HPA commercial catalyst and NH4 + ion-exchanged Brønsted groups of mesoporous Al-SBA-15 support (Si/Al molar ratio of 15) showed the highest acidity and catalytic activity (ethyl acetoacetate conversion of 93.49 wt%) in comparison to HPA commercial catalyst as well as to the other catalysts. In addition, this catalyst also showed good catalytic stability after five reaction cycles with slightly reduction of activity, suggesting the prospect of employing HPA/Al-SBA-15 catalyst for organic synthesis of polar compounds.

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<p>Introducing additional meso- or macroporosity into traditionally microporous metal-organic frameworks (MOFs) is a very promising way to improve the catalytic performance of these materials, mostly due to the resultant reductions of diffusional barriers during liquid-phase or gas-phase reactions. Here we show that HKUST-1 can be successfully synthesised either via post-synthetic treatment (etching prepared HKUST-1 samples in phosphoric acid, here called HKUST AE) or via <i>in situ</i> crystallisation (exposing the MOF precursor solution to supercritical CO₂, here called HKUST CO₂) to produce hierarchically porous structures that are highly beneficial for catalysis. These hierarchical MOFs were characterised by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) and gas sorption to confirm the preservation of the microscopic structure and the appearance of macropores in the crystallites. More importantly, the benefits of introducing these hierarchical porous structures into this MOF for improving the diffusion accessibility of reagents to the sample in catalysed liquid- and gas-phase reactions were quantified for the first time. It was found that the hierarchical pore structure helped to increase the reaction conversion of styrene oxide methanolysis (by ~65 % using either HKUST AE and HKUST CO₂, at 40 ^oC in 25 min) and CO oxidation (by 55 % using HKUST CO₂ at 260 ^oC). These findings demonstrate the advantage of using hierarchical porous MOFs in catalysis.</p>