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A fast and effective method for the preparation of NaTaO3 nanomaterials reported here is ultrasonic method with immersed sonotrode in the reaction medium followed by annealing at 600 °C. In order to remove the organic material and increase phase crystallinity, the materials were annealed at different temperatures (400, 600, 800 °C), for 6 h. The as-prepared samples were characterized by X-ray diffraction (XRD), thermal analysis (TG/DTG/HF), IR spectroscopy, surface area analysis (BET), and scanning electron microscopy (SEM/EDX). The structural characterization by X-ray powder diffraction revealed that heat-treated materials at 600 °C are well crystallized and the average size of the crystallites being approximately 60 nm, confirmed also by scanning electron microscopy. Thermal analysis has revealed five transformations process of NaTaO3, the highest mass loss (10.67 %) taking place in the range 23–323.5 °C. It was found that the BET surface area decreases with temperature increasing which indicates a change in pores due to the removal of organics. From morphological analysis, it can be seen that particles have spherical shape and EDX revealed the purity of obtained materials.

A series of heteropolyacids (HPA)–silica composites were prepared from H3PMo12O40 (HPM) and H4PVMo11O40 (HPVM) by chemically anchoring to the amine-functionalized mesoporous MCM-41 and SBA-15. These composites were characterized by FT-IR, XRD, N2 adsorption, SEM, and TEM for their structural integrity and physicochemical properties. The effect of the support on thermal stability was investigated by TG–DTG and DTA. The evolved gases during the thermal analysis of prepared composites were identified by online mass spectrometry coupled with TG technique. It was evidenced that HPAs species were finely dispersed on amine-functionalized molecular sieves via chemical immobilization and the structure of the HPAs is preserved over mesoporous materials. From thermal analysis of HPA–silica composites was observed an important mass loss above 553 K which is due to the decomposition of amino propyl functional group. For this reason prepared composites can be utilized as dispersed catalysts for the reactions performed below 553 K. Catalytic properties of these composites were studied by using ethanol conversion at different temperatures. The HPA supported on molecular sieves exhibited an enhanced oxidation catalytic activity (formation of acetaldehyde) and a lower acid catalytic activity (formation of ethylene and diethyl ether) compared to the parent catalysts. The favorable effect of HPAs deposition on silica supports for oxidehydrogenation pathway to acetaldehyde results from the examination of and reaction rate values. For all reaction temperatures, the reaction rates of acetaldehyde formation are higher for supported samples than unsupported ones.