MOFs derived mesoporous Co3O4 polyhedrons and plates for CO oxidation reaction

LaNiO3 Perovskite Synthesis through the EDTA–Citrate Complexing Method and Its Application to CO Oxidation

A series of LaNiO3 materials were synthesized by the EDTA–citrate complexing method, modifying different physicochemical conditions. The LaNiO3 samples were calcined between 600 and 800 °C and characterized by XRD, SEM, XPS, CO-TPD, TG, DT, and N2 adsorption. The results evidence that although all the samples presented the same crystal phase, LaNiO3 as expected, some microstructural and superficial features varied as a function of the calcination temperature. Then, LaNiO3 samples were tested as catalysts of the CO oxidation process, a reaction never thoroughly analyzed employing this material. The catalytic results showed that LaNiO3 samples calcined at temperatures of 600 and 700 °C reached complete CO conversions at ~240 °C, while the sample thermally treated at 800 °C only achieved a 100% of CO conversion at temperatures higher than 300 °C. DRIFTS and XRD were used for studying the reaction mechanism and the catalysts’ structural stability, respectively. Finally, the obtained results were compared with different Ni-containing materials used in the same catalytic process, establishing that LaNiO3 has adequate properties for the CO oxidation process.

A catalyst powder-based spraying approach for rapid and efficient removal of fire-generated CO：From laboratory to pilot scale

In confined space fires, the large amount of CO generated by incomplete combustion of carbon-based materials poses a serious threat to the trapped people. However, the efficient method of removing CO in such disasters remains a great challenge. Herein, a spraying catalyst powder (SCP) approach is proposed for CO removal by oxidizing CO to harmless CO₂. Cu/Mn catalyst, synthesized by using ethylene glycol as solvent, was employed in this study. The influence of catalyst concentration, temperature, CO₂ concentration and initial CO concentration on CO removal performance of SCP approach was investigated. With 500 g/m³ catalyst, 25,000 ppm CO could be reduced to 2550 ppm within 1 min and completely removed in less than 2.83 min at 200 °C. The feasibility of SCP approach in practical application was validated by the remarkable CO removal performance for charcoal combustion in confined tunnel. SCP approach could effectively reduce the CO concentration, which would reach up to 12,659 ppm in the absence of SCP approach, to less than 1500 ppm within 30 min. The experiment results suggest that SCP technology can effectively remove the fire-generated CO and is promising for practical application in crowded occupancies, such as underground space and aircraft compartment.

A CeCoOx Core/Nb2 O5 @TiO2 Double-Shell Nanocage Catalyst Demonstrates High Activity and Water Resistance for Catalytic Combustion of o-Dichlorobenzene

A series of catalysts with different core-shell structures has been successfully prepared by a hydrothermal method. They consisted of CeCoO_x @TiO₂ (single shell), CeCoO_x @Nb₂ O₅ (single shell) and CeCoO_x @Nb₂ O₅ @TiO₂ (double shell) core-shell nanocages and CeCoO_x nanocages, in which CeCoO_x was the core and TiO₂ and Nb₂ O₅ were shells. The influence of the core-shell structure on the catalytic performance of o-dichlorobenzene was investigated by activity, water-resistance, and thermal stability tests as well as catalyst characterization. The temperatures corresponding to 90 % conversion of o-dichlorobenzene (T₉₀ ) of CeCoO_x , CeCoO_x @TiO₂ , CeCoO_x @Nb₂ O₅ , and CeCoO_x @Nb₂ O₅ @TiO₂ catalysts were 415, 383, 362 and 367 °C, respectively. CeCoO_x @Nb₂ O₅ exhibited excellent catalytic activity, mainly owing to the special core-shell structure, large specific surface area, abundant activity of Co³⁺ , Ce³⁺ , Nb⁵⁺ , strong reducibility, and more active oxygen vacancies. It can be seen that the Nb₂ O₅ coating can greatly improve the catalytic activity of the catalyst. In addition, due to the protective effect of the TiO₂ shell on CeCoO_x , CeCoO_x @Nb₂ O₅ @TiO₂ catalysts exhibited outstanding thermal and hydrothermal stability for 20 hours. The T₉₀ of CeCoO_x @Nb₂ O₅ @TiO₂ was slightly lower than that of CeCoO_x @Nb₂ O₅ , but it had higher stability and hydrothermal stability. Furthermore, possible reaction pathways involving the Mars-van-Krevelen (MvK) and Langmuir-Hinshelwood (L-H) models were deduced based on studies of the temperature-programmed desorption of O₂ (O₂ -TPD), X-ray photoelectron spectroscopy (XPS), and in situ diffuse reflectance FTIR spectroscopy (DRIFTS) characterization.

Controlling the morphology of metal–organic frameworks and porous carbon materials: metal oxides as primary architecture-directing agents

We give a comprehensive overview of how the morphology control is an effective and versatile way to control the physicochemical properties of metal oxides that can be transferred to metal–organic frameworks and porous carbon materials.