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

Abstract

environmental compatibility. [2] However, the coexistence of NO and SO 2 in the flue gas makes the deactivation of the traditional catalysts, due to the competition adsorption of SO 2 and NO on the active sites of the catalyst surface, resulting in the change of catalyst structure and the decrease of NO conversion efficiency.Recently, many researchers have been focused on tuning the structures of the catalysts to avoid the poison effect caused by SO 2 . The design of active components with the construction of a unique hollow structure presents the enhanced catalytic performance on NO oxidation with the existence of SO 2 . [3] The cavity confinement effect of the hollow nanoreactor could realize the impact on the unique electronic and geometric structure for enhancing the charge transfer and separation in the temporal-spatial catalytic process. [4] The charge transfer induced by the hetero-shelled hollow structure may change the catalytic activity and selectivity. [5] Besides, more interesting catalysts have been developed and applied to NO oxidation, such as composites structure control from one dimensional to three dimensional, [6,7] surface active site including defects engineering, [8,9] and catalytic sites tuning on synergetic conversion. [2,10] Non-thermal plasma(NTP) technology has attracted lots of research attention for NO catalytic removal. [11] The combination of NTP and catalyst can promote the formation of reaction intermediates on the catalyst surface, thus reducing the activation energy of the reaction, and achieving the rapid selective catalytic oxidation of NO at low temperatures. [12][13][14][15] In fact, many researchers attentions have been paid to tune the engineering parameters of the NTP and the advanced catalyst structure design without exploring the synergetic effect on the temporal-spatial structure, which may induce spatial charge rearrangement and trigger the micro-domain surficial species reaction. For instance, Cui et al. [16] studied the process of simultaneous oxidation of NO and SO 2 using non-thermal plasma coupled with catalyst on engineering parameters control. They found that the oxidation efficiency of both NO and SO 2 could be significantly improved in conjunction with further oxidation by the wet electrostatic precipitator (WESP). Furthermore, because of the unique properties of the hetero-shelled hollow structure catalyst, it may also be easier to produce synergistic 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 SO 2 (1000 mg m -3 ) and NO (200 mg m -3 ). Impressively, precise surface characterization ...

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

“…It is well known that surface chemisorbed oxygen plays a crucial role in the oxidation reaction . We speculate that the hydrothermal method produces more coordination-unsaturated chemical bonds on the surface of the catalyst, increasing the content of the chemisorbed oxygen and Co 2+ /(Co 2+ + Co 3+ ) Figure c shows the peaks at 457.8–457.9 and 463.5–463.6 eV in two catalysts, which could be attributed to Ti 2p 3/2 and Ti 2p 1/2 , respectively, in good agreement with the presence of TiO 2 .…”

“…The enhancement of the charge transfer and the generation of more energetic electrons can effectively accelerate the reactions in the plasma-catalytic process. Hence, eqs and may occur more rapidly on the Co 3 O 4 /TiO 2 -3DHS catalyst surface. , NO + normalO * → NO 2 NO + normalO 3 → NO 2 + normalO 2 When the catalyst is used in an actual industrial flue gas, the SO 2 tolerance of the catalyst must be evaluated because the coexistence of SO 2 may be detrimental to the catalyst. To this end, we designed a comparative experiment, and the effect of SO 2 on the oxidation efficiency of NO was investigated.…”

“…In addition, the conversion efficiency of SO 2 is lower than that of NO in the given V P–P range, which is directly related to the fact that the reaction rate constants of NO with O* and O 3 are much higher than those of SO 2 with O* and O 3 . , SO 2 + normalO * → SO 3 SO 2 + normalO 3 → SO 3 + normalO 2 Figure d evaluates the catalytic oxidation efficiency of NO under the coexistence of SO 2 and H 2 O. It is known that H 2 O is usually used as a source to generate OH* in the NTP process via eq . , From Figure d, it can be seen that the incorporation of water vapor significantly reduces the catalytic activity of Co 3 O 4 /TiO 2 under low V P–P (21–25 kV) conditions, which is consistent with our previous study. , One of the reasons is that H 2 O will capture a large number of electrons, resulting in the reduction of high-energy electrons. Another reason is that H 2 O will compete with NO for active sites on the catalyst surface. ,, When V P–P increases from 25 to 29 kV, the discharge energy increases gradually.…”

“…As far as flue gas denitrification is concerned, the traditional selective catalytic reduction (SCR) technology has been extensively applied, − while its capacity to remove nitric oxide (NO) from flue gas is far from ideal due to conflicting redox effects . Under such a context, catalytic oxidation of NO has emerged as a promising approach due to its flexibility, controllability, and wide applicability . Among various NO oxidation methods, nonthermal plasma (NTP) technology, highlighted by its rapid thermodynamics at low temperatures, has attracted much attention.…”

“…So far, NTP technology needs to address two main challenges before industry-level flue gas denitrification, namely, catalyst poisoning associated with the coexistence of SO 2 and H 2 O and discharge efficiency, as determined by the synergistic effect between the catalyst and the plasma, both of which underline the significance of the rational design of advanced catalysts. Transition metals manifest a diverse range of valence states, while their oxides demonstrate pronounced redox capabilities, thereby establishing them as a ubiquitous option for the fabrication of catalysts. , Owing to its abundance, low cost, chemical stability, and resistance to acids and bases, titanium dioxide (TiO 2 ) is a commonly employed synthetic material in the manufacture of commercial catalysts. , In the literature, the combination of transition-metal oxides as active components and TiO 2 as a support has been well demonstrated as high-performance catalysts for NO removal under the NTP scheme. − So far, extensive efforts have been made in the screening of transition-metal active components, from the optimization of active components to delicate engineering of favorable hollow structures, , such as the combination of three-dimensional hollow geometries of TiO 2 coupled with Fe 1 /TiO 2 microspheres and Pd@TiO 2 @ZnIn 2 S 4 nanobox. , As demonstrated by these studies, the key value of the confinement effect associated with hollow nanoreactors has been well established, such as the impact on the electronic and geometric structure of active sites, which plays an essential role in charge transfer and separation. ,, …”