Influence of wet flue gas desulfurization on the pollutants monitoring in FCC flue gas

Unique Cluster-Support Effect of a Co3O4/TiO2-3DHS Nanoreactor for Efficient Plasma-Catalytic Oxidation Performance

For environmental catalysis, a central topic is the design of high-performance catalysts and advanced mechanism studies. In the case of the removal of flue gas pollutants from coal-fired power plants, highly selective nanoreactors have been widely utilized together with plasma discharge characteristics, such as the catalytic oxidation of NO. Herein, a novel reactor with a three-dimensional hollow structure of TiO₂ confining Co₃O₄ nanoclusters (Co₃O₄/TiO₂-3DHS) has been developed for plasma-catalytic oxidation of NO, whose performance was compared with that of the commercial TiO₂ confining Co₃O₄ cluster (Co₃O₄/TiO₂). Specifically, Co₃O₄/TiO₂-3DHS presented a higher efficiency (almost 100%) within lower peak-peak voltage (V_P-P). More importantly, the NO oxidation efficiency was between 91.5 and 94.5% after a long time of testing, indicating that Co₃O₄/TiO₂-3DHS exhibits more robust sulfur and water tolerance. Density functional theory calculations revealed that such impressive performance originates from the unique cluster-support effect, which changes the distribution of the active sites on the catalyst surface, resulting in the selective adsorption of flue gas. This investigation provides a new strategy for constructing a three-dimensional hollow nanoreactor for the plasma-catalytic process.

Emission characteristics of benzene series in FCC flue gas

Benzene series are considered as air pollutants in refineries. However, the emissions of benzene series in fluid catalytic cracking (FCC) flue gas are poorly understand. In this work, we conduct stack tests on three typical FCC units. Benzene series, including benzene, toluene, xylene and ethyl benzene, are monitored in the flue gas. It shows that the coking degree of the spent catalysts affect the emissions of benzene series significantly, and there are four kinds of carbon-containing precursors in the spent catalyst. A fixed-bed reactor is used to conduct the regeneration simulation experiments, and the flue gas is monitored by TG-MS and FTIR. The emissions of toluene and ethyl benzene are mainly emitted in the early and middle stage of the reaction (250-650 °C), while the emission of benzene is mainly detected in the middle and late stage of the reaction (450-750 °C). Xylene group is not detected in the stack tests and regeneration experiments. Higher emissions of benzene series are released from the spent catalyst with lower C/H ratio during regeneration process. With the increase of oxygen content, the emissions of benzene series decrease, and the initial emission temperature is advanced. These insights can improve the refinery's awareness and control of benzene series in the future.

On-Line Thermally Induced Evolved Gas Analysis: An Update-Part 1: EGA-MS

Advances in on-line thermally induced evolved gas analysis (OLTI-EGA) have been systematically reported by our group to update their applications in several different fields and to provide useful starting references. The importance of an accurate interpretation of the thermally-induced reaction mechanism which involves the formation of gaseous species is necessary to obtain the characterization of the evolved products. In this review, applications of Evolved Gas Analysis (EGA) performed by on-line coupling heating devices to mass spectrometry (EGA-MS), are reported. Reported references clearly demonstrate that the characterization of the nature of volatile products released by a substance subjected to a controlled temperature program allows us to prove a supposed reaction or composition, either under isothermal or under heating conditions. Selected 2019, 2020, and 2021 references are collected and briefly described in this review.

Hetero-Shelled Hollow Structure Coupled with Non-Thermal Plasma Inducing Spatial Charge Rearrangement for Superior NO Conversion and Sulfur Resistance

Facilitating the mass transfer and spatial charge separation is a great challenge for achieving efficient oxidation of NO and outstanding sulfur resistance. Herein, a hydrothermal-assisted confinement growth technique is used to fabricate well-defined three-dimensional CuOx@MnOx hetero-shelled hollow-structure catalysts. By integrating the coupled plasma space reactor and the porous hierarchical structure of the catalyst, excellent stability (10 h) and high conversion of NO (93.86%) are reached under the concentration of SO₂ (1000 mg m^-3 ) and NO (200 mg m^-3 ). Impressively, precise surface characterization and detailed density functional theory calculations show that the spatial hetero-shelled micro-reactor can orient the redox pairs transportation, facilitating the combination of NO with the surface coordinately unsaturated O atoms, and also prevent the poisoning of SO₂ molecules due to the curvature and surface charge effect in the non-thermal plasma equipment.