Oxidation and hydrogenation catalysis plays a crucial role in the current chemical industry for the production of key chemicals and intermediates. Because of their easy separation and recyclability, supported catalysts are widely used in these two processes. Layered double hydroxides (LDHs) with the advantages of unique structure, composition diversity, high stability, ease of preparation and low cost have shown great potential in the design and synthesis of novel supported catalysts. This review summarizes the recent progress in supported catalysts by using LDHs as supports/precursors for catalytic oxidation and hydrogenation. Particularly, partial hydrogenation of acetylene, hydrogenation of dimethyl terephthalate, methanation, epoxidation of olefins, elimination of NO_x and SO_x emissions, and selective oxidation of biomass have been chosen as representative reactions in the petrochemical, fine chemicals, environmental protection and clean energy fields to highlight the potential application and the general functionality of LDH-based catalysts in catalytic oxidation and hydrogenation. Finally, we concisely discuss some of the scientific challenges and opportunities of supported catalysts based on LDH materials.

Quantum-sized ZnO nanoparticles have been synthesized at room temperature by a mild sol–gel process using tetraethylorthosilicate (TEOS) as the capping agent to control the particle growth of ZnO. The crystal structure, particle size and optical properties have been investigated by X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), photoluminescence (PL) spectra and Raman spectra, respectively. The results show that the ZnO nanoparticles exhibit hexagonal wurtzite structure and the average crystallite size is 5.7 nm which is a little less than TEM results. It has been testified by room-temperature PL spectra that the TEOS capped the surface of ZnO nanoparticles and obviously reduced grain size, as an emission at 520 nm almost disappeared and a new peak with an anomalous blue shift as great as 9 nm, appeared for the TEOS capped ZnO. The sensing tests indicate that the ZnO based sensors not only show a high response to NO₂ but also exhibit high selectivity over CO and CH₄ at a low operating temperature of 290 °C. The response increases with NO₂ concentration and decreases with calcination temperature, and is in agreement with Raman and XRD results.