Volatile organic compounds (VOCs) are important precursors for the formation of secondary pollutants, such as fine particulate matter (PM) and ozone (O₃), which will lead to severe atmospheric environmental problems to restrict the sustainable development of the social economy. Catalytic oxidation is a safe, eco-friendly, and simple method for eliminating VOCs, which can be converted into CO₂ and H₂O without the generation of other harmful substances. The fabrication and development of catalysts are very crucial to enhance the catalytic oxidation efficiency of the removal of VOCs. The noble metal catalyst is one of the commonly used catalysts for the catalytic oxidation of VOCs because of the high reaction activity, good stability, poisoning-resistant ability, and easy regeneration. In this review, the research progress of noble metal (Pt, Pd, Au, Ag, and Ir) catalysts for the removal of VOCs in recent years was summarized with the discussion of the influence factors in the preparation process on the catalytic performance. The reaction mechanisms of the removal of VOCs over the corresponding noble metal catalysts were also briefly discussed.

Hierarchical zeolites attract people’s attention due to their enhanced mass transfer properties in catalytic reactions. The research over obtaining these zeolites in green and efficient methods is of great significance for the current post-treatments and templating strategies tend to be costly for hierarchical zeolite synthesis. In this research, nanosized mesoporous ZSM-5 (SN-ZSM-5) zeolites have been synthesized without the addition of mesoscale templates under highly concentrated conditions. The physicochemical characteristics were systematically investigated by XRD, SEM, N2 sorption, TEM, and NMR. The SEM images showed ZSM-5 crystals with sizes between 50–110 nm were obtained. N₂ sorption and high-resolution TEM images gave direct evidence for the hierarchical structure of SN-ZSM-5. The forming mechanism for the hierarchical structure was proposed that the etching effect of the highly alkaline environment for the starting gels played a critical role in the formation of hierarchical structure. Catalytic tests in methanol-to-olefins (MTO) showed the SN-ZSM-5 performed a longer catalyst lifetime and higher propylene selectivity than the conventional ZSM-5 zeolites (C-ZSM-5) obtained from a traditional hydrothermal method. The features of hierarchical structure in the SN-ZSM-5 crystals and the sustainability for synthesis method could show a promising choice for wide applications of these SN-ZSM-5 zeolites in the future.

Pd/TiO ₂ catalysts were designed with different crystals to study the SMSIs effects. The temperature at which 90% O ₂ conversion was achieved on Pd/a-TiO ₂ could reach up to 150 °C, which is ∼1.4 times (107 °C) that of the Pd/r-TiO ₂ .

A series of alkali metal (Li, Na, and K)-modified Pd catalysts and Pd/Al₂O₃ were prepared and used to remove oxygen in a propylene flow with hydrogen’s existence. The results showed that the alkali metals could enhance the performance of the Pd catalysts and the effect followed the order of K > Na > Li. X-Ray diffraction (XRD), N₂-physisorption, transmission electron microscopy (TEM), hydrogen temperature programmed reduction (H₂-TPR), and X-ray photoelectron spectroscopy (XPS) were carried out to investigate the alkali metal-modified Pd catalysts and the promotional effect mechanism was explained. The results showed that alkali metal modification increased the electron density of Pd atoms to induce the negatively charged Pd species, which could enhance the adsorption of oxygen while weakening the adsorption of propylene, and then enhance the performance of the modified catalysts for oxygen removal from unsaturated hydrocarbon. The Pd-K/A catalyst performed the best on both oxygen removal and propylene hydrogenation inhibition.

Propane catalytic oxidation is an important industrial chemical process. However, poor activity is frequently observed for stable C–H bonds, especially for non-noble catalysts in low temperature. Herein, we reported a controlled synthesis of catalyst Co₃O₄@CeO₂–IE via inverse loading and proposed a strategy of oxygen vacancy for its high catalytic oxidation activity, achieving better performance than traditional supported catalyst Co₃O₄/CeO₂–IM, i.e., the T₅₀ (temperature at 50% propane conversion) of 217 °C vs. 235 °C and T₉₀ (temperature at 90% propane conversion) of 268 °C vs. 348 °C at the propane space velocity of 60,000 mL g⁻¹ h⁻¹. Further investigations indicate that there are more enriched oxygen vacancies in Co₃O₄@CeO₂–IE due to the unique preparation method. This work provides an element doping strategy to effectively boost the propane catalytic oxidation performance as well as a bright outlook for efficient environmental catalysts.