Pd/SiO2 Catalysts Prepared via a Dielectric Barrier Discharge Hydrogen Plasma with Improved Performance for Low-Temperature Catalytic Combustion of Toluene

Close-Contact Oxygen Vacancies Synthesized by FSP Promote the Supplement of Active Oxygen Species To Improve the Catalytic Combustion Performance of Toluene

Catalytic combustion is an important means to reduce toluene pollution, and improving the performance of catalytic combustion catalysts is of great significance for practical applications. The study of oxygen vacancies is one of the key steps to improve catalyst performance. Here, two different oxygen vacancy structures were well-defined and controllably synthesized by flame spray pyrolysis (FSP) to evaluate their effect on the catalytic combustion performance of toluene. The closely contacted oxygen vacancies (c-Vo) enhance the oxygen activation capacity of the catalyst, and the temperature of the first oxygen desorption peak and hydrogen reduction peak is 56 and 37 °C lower than the separated oxygen vacancy (s-Vo) sample, respectively. The oxygen activation energy barrier on the c-Vo is calculated to be negligible of only 0.04 eV. Both in situ DRIFT and DFT calculations indicate that the c-Vo structure accelerates the catalytic oxidation of p-toluene molecules. Moreover, due to the unique characteristics of high-temperature synthesis and rapid quenching, FSP brings excellent water resistance and high-temperature stability to the catalyst. In conclusion, utilizing the FSP in situ reduction strategy can create more c-Vo to improve the catalytic combustion performance of toluene.

Non-thermal plasma synthesis of supported Cu-Mn-Ce mixed oxide catalyst towards highly improved catalytic performance for volatile organic compound oxidation

Compared with that of the transition metal mixed oxide pellet catalyst, the catalytic activity of the supported mixed oxide catalyst was significantly reduced, which was limited in practical industrial applications. In this work, supported Cu-Mn-Ce mixed oxide catalysts were prepared by non-thermal plasma. Catalyst characterization result demonstrated that plasma treatment could promote the proportion of oxygen vacancy and enhance the adsorptive strength of VOCs on the surface of catalyst. Meanwhile, plasma treatment process exerted a slight influence on the pore structure and morphological property of the catalyst. Consequently, CMC/SiO₂-P exhibited much higher catalytic activity than CMC/SiO₂ prepared by the incipient wetness impregnation method for the catalytic oxidation of toluene and n-hexane. Among the catalysts prepared, the 15%CMC/SiO₂-P catalyst even exhibited a high catalytic activity comparable to that of the supported noble metal catalyst for the oxidation of the inert hexane. The T₉₈ of toluene and n-hexane over 15%CMC/SiO₂-P was 260 and 280°C under the conditions of VOC concentration at 1000 ppm and WHSV at 20,000 mL·g^-1·h^-1, respectively. This work provided a novel method for the preparation of the supported transition metal mixed oxide catalyst.

A review of the advances in catalyst modification using nonthermal plasma: Process, Mechanism and Applications

With the continuous development of catalytic processes in chemistry, biology, organic synthesis, energy generation and many other fields, the design of catalysts with novel properties has become a new paradigm in both science and industry. Nonthermal plasma has aroused extensive interest in the synthesis and modification of catalysts. An increasing number of researchers are using plasma for the modification of target catalysts, such as modifying the dispersion of active sites, regulating electronic properties, enhancing metal-support interactions, and changing the morphology. Plasma provides an alternative choice for catalysts in the modification process of oxidation, reduction, etching, coating, and doping and is especially helpful for unfavourable thermodynamic processes or heat-sensitive reactions. This review focuses on the following points: (i) the fundamentals behind the nonthermal plasma modification of catalysts; (ii) the latest research progress on the application of plasma modified catalysts; and (iii) main challenges in the field and a vision for future development.