Journal of Physical Chemistry C
·
2021
·
IF 4.126
Yanye Zhu,Fangyuan Zhou,Xiaoqiang Wang,Yue Liu,Zhongbiao Wu
The NH3–SCR process could provide cobenefits for VOCs abatement from industrial sources. Ceria-based catalysts have received considerable attention for NOx removal at low-medium temperatures. In this study, the reaction behaviors of the simultaneous control of NOx and methanol over the Sb0.5CeZr2Ox catalyst were investigated. It was found that the presence of methanol reduced NOx conversion at low temperatures, while the methanol mineralization rate was promoted in the SCR reaction environment. This effect weakened as the temperature increased, and both NOx and methanol could be effectively removed (with efficiencies more than 90%) within 250–350 °C at a CH3OH/NO ratio of no more than 1:1. NO adsorption and oxidation were greatly suppressed by methanol, thereby inhibiting the SCR reaction via the Langmuir–Hinshelwood (L-H) mechanism. Meanwhile, the formation of formamide via NH3 and intermediates of methanol oxidation was also responsible for the deactivation effect on the SCR reaction at low temperatures. The presence of NO was found to be the main reason for enhanced methanol deep oxidation as NO can promote the rehealing process of active oxygen species.
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CHEMICAL ENGINEERING JOURNAL
·
2020
·
IF 10.652
JiaYu Chen,Peng Fu,Daofei Lv,Yang Chen,Meiling Fan,Junliang Wu,Amogh Meshram,Bin Mu,Xiang Li,Qibin Xia
A high-performance denitration catalyst based on Mn-Ce mixed-oxide derived from a specific Mn/Ce precursorwas fabricated by solvothermal method. It exhibited outstanding low-temperature activity, which achieved above 90% NO x conversion in the temperature of 150–310 °C. Remarkably, Mn-Ce mixed-oxide demonstrated a much better SO 2 tolerance, in which the NO x conversion increased from 92.6% to 97.8% at 150 °C after introducing 200 ppm SO 2 . The synthesized Mn-Ce mixed-oxide has a porous structure with abundant chemisorbed oxygen spices and exposed active sites. In addition, the increased acidity and redox capacity enhanced the catalytic activity after introducing SO 2 . Meanwhile, the injection of SO 2 separates NH 3 adsorption sites from oxidation agents, inhibiting the unwanted oxidization of ammonia to nitrogen oxides. Furthermore, the reaction pathway on Mn-Ce mixed-oxide proved to be the L-H mechanism based on in situ DRIFTS. Thus, the synthesized Mn-Ce mixed oxide demonstrated an excellent denitration performance and the especially high SO 2 tolerance, showing great potential for low-temperature NH 3 -SCR.
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CHEMICAL ENGINEERING JOURNAL
·
2020
·
IF 10.652
Peng Zhang,Yu Huang,Yongfang Rao,Meijuan Chen,Xinwei Li,Wingkei Ho,Shuncheng Lee,Junji Cao
Bulk materials with a microporous structure are adverse to light adsorption, photoelectron and reactant transport in a photocatalytic reaction. Mesoporous photocatalysts have shown many marked advantages in photocatalytic fields. Herein, uniform mesoporous Bi@Bi 2 O 3 nanospheres were fabricated by HCl–ethanol chemical etching at low temperature (60 °C). The obtained mesoporous photocatalysis increased the NO removal efficiency (16%) and inhibited toxic NO 2 generation (3%) under visible light irradiation. Further oxidation of Bi and calcination at high temperatures were avoided during template removal. Moreover, the as-prepared sample possessed a remarkably narrower pore size distribution (3.2–3.9 nm) and stronger light and NO adsorption ability than the bulk microporous Bi@Bi 2 O 3 . Work function and the electron spin resonance test results also indicated that the position of the entire energy bands on Bi 2 O 3 was lowered. The amount of reactive oxygen species generated over the uniform mesoporous structure was higher than that over bulk Bi@Bi 2 O 3 . However, photoelectrochemical measurements indicated that the separation efficiencies of the photo-generated carriers were not improved over the uniform mesoporous Bi@Bi 2 O 3 . Comprehensive studies have shown that the oxidation ability rather than the enhanced separation efficiency of charge carriers accounted for the enhanced photocatalytic activity. This work elucidates the roles of a uniform mesoporous structure in NO x photocatalytic oxidation and provides an efficient strategy for structural engineering in preparing highly reactive and practical photocatalysts.
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ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
·
2020
·Vol. 27
·期 22
·27663-27673
·
IF 3.056
Liu Yuan-zhen,Xu Qi-yan,Guo Rui-tang,Duan Chao-peng,Wu Gui-lin,Miao Yu-fang,Gu Jing-wen
The Cu/TiO 2 catalysts with the addition of Eu were developed by the sol-gel way for the selective catalytic reduction (SCR) of NO x by NH 3 . Activity tests revealed that CuEu/TiO 2 -0.15 catalyst showed the optimal de-NO x performance in a wide temperature range (150–300 °C), along with an admirable SO 2 tolerance. According to characterization analysis, the relationship between the NH 3 -SCR performance and physicochemical characters of samples was explored. The adjunction of Eu on Cu/TiO 2 catalyst can contribute to the formation of a large amount of Cu 2+ , adsorbed oxygen, and acid sites on the catalyst surface. Moreover, the Eu addition on Cu/TiO 2 is favorable to the generation of activated NO x and NH 3 substances adsorbed on the catalyst surface, which would conduce to the NH 3 -SCR process by Langmuir-Hinshelwood (L-H) mechanism effectively.
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APPLIED CATALYSIS A-GENERAL
·
2014
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IF 3.674
Xiuquan Jia,Jiping Ma,Min Wang,Zhongtian Du,Fang Lu,Feng Wang,Jie Xu
The promoted effect of Cu(NO 3 ) 2 on aerobic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-diformylfuran (DFF) catalyzed by VOSO 4 in acetonitrile was intensively investigated. It was revealed that Cu(NO 3 ) 2 facilitated the activation of VOSO 4 to generate active V 5+ species via the generation of NO x gas. The high DFF selectivity is ascribed to Cu 2+ cation which can effectively prohibit oxidative C C bond cleavage reaction of HMF and prevent radical reaction of DFF to humins. In addition, the polarity of solvent plays a great role on high selectivity of DFF.
研究领域:
催化
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化学工程
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有机化学
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NEW JOURNAL OF CHEMISTRY
·
2025
·Vol. 49
·期 29
·12875-12883
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IF 2.5
Ruoxuan Bai,Rongkun Jiang,Zixiao Yu,Junqi Wang,Yiqing Zeng,Shule Zhang
A number of efforts have been made to improve the NH3-SCR activity of MnOx based catalysts at low temperature, but few studies have focused on their long-term stability. In this study, MnOx/TiO2 (MnTi) catalysts prepared via wet impregnation were subjected to 30-h long-term stability tests under laboratory conditions to investigate their stability for the selective catalytic reduction (NH3-SCR) of NOx at low temperatures (80–200 °C), and combined with XRD, BET, XPS, H2-TPR, and in situ DRIFTS analysis to elucidate deactivation mechanisms. The results show that the reaction temperature has a great influence on the formation, decomposition, and transformation of nitrate species. Nitrate species, especially stable nitrate species, continuously accumulate on the catalyst surface at relatively low temperatures (≤160 °C in this work), which might block the active sites and hinder the conversion of Mn3+ to Mn4+, thereby leading to deactivation of the MnTi catalyst. In contrast, nitrate species on the catalyst surface can react or decompose rapidly at a high enough temperature (≥200 °C in this work), which facilitates the exposure of active sites and dynamic equilibrium of the Mn4+/Mn3+ redox cycle, resulting in the high long-term stability. We expect that this work will arouse researchers’ attention toward the long-term stability of NH3-SCR catalysts in the study of improving their catalytic activity at low temperature.
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APPLIED SURFACE SCIENCE
·
2019
·
IF 5.155
Zhong-yi Wang,Rui-tang Guo,Zhen-zhen Guan,Xu Shi,Wei-guo Pan,Zai-guo Fu,Hao Qin,Xing-yu Liu
A sequence of Cr-modified CeZr 2 O x catalysts were synthesized through the co-precipitation way and applied in selective catalytic reduction (SCR) of NO x with ammonia. The optimal catalyst (Cr 1 CeZr 2 O x ) exhibited the excellent NH 3 -SCR activity and high SO 2 resistance. From the characterization results, Cr species in Cr 1 CeZr 2 O x could suppress the formation of ZrO 2 crystals, which could also contribute to stronger surface acidity and reducibility . Besides, more Ce 3+ and surface adsorbed oxygen species were observed on Cr 1 CeZr 2 O x catalyst. On the basis of in situ DRIFT experiments, it could be confirmed that the NH 3 -SCR process on Cr 1 CeZr 2 O x was promoted through Langmuir-Hinshelwood (L-H) mechanism. Besides, the improved NO oxidation and more ad-NO x and ad-NH 3 also played a vital role for the superior low-temperature SCR activity of Cr 1 CeZr 2 O x .
研究领域:
催化化学
·
环境科学
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CHEMOSPHERE
·
2023
·
IF 8.8
Guobo Li,Yaping Zhang,Peng Wu,Kai Shen,Shule Zhang,Shipeng Ding
The synergistic degradation of VOCs and NO x that were emitted from the incineration of municipal and medical wastes by a single catalyst is challenging, due to the poor activity at low temperatures, and the SO 2 poisoning on the active sites. Herein, N-doped TiO 2 (N–TiO 2 ) was used as the support for designing a highly efficient and stable catalyst system for CB/NO x synergistic degradation even in the presence of SO 2 . The prepared SbPdV/N–TiO 2 catalyst, which presented excellent activity and tolerance to SO 2 in the CBCO + SCR process, was investigated by a series of characterizations (such as XRD, TPD, XPS, H 2 -TPR and so on) as well as DFT calculations . The electronic structure of the catalyst was effectively modulated after N doping, resulting in effective charge flow between the catalyst surface and gas molecules. More importantly, the adsorption and deposition of sulfur species and reaction transient intermediates on active centers were restrained, while a new N adsorption center for NO x was provided. Abundant adsorption centers and superior redox properties ensured smooth CB/NO x synergistic degradation. The removal of CB mainly follows the L-H mechanism, while NO x elimination follows both E-R and L-H mechanisms. As a result, N doping provides a new approach to develop more advanced anti-SO 2 poisoning CB/NO x synergistic catalytic removal systems for extensive applications.
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APPLIED CATALYSIS B-ENVIRONMENTAL
·
2019
·
IF 14.229
Huawang Zhao,Yingnan Zhao,Mengke Liu,Xianghui Li,Yuhan Ma,Xin Yong,Hong Chen,Yongdan Li
Phosphorus is introduced to modify the Cu-SSZ-13 catalyst via incipient wetness impregnation, with P/Cu-SSZ-13 = 1 and 2 wt.%, and Si/Al = 4, for selective catalytic reduction of NOx with NH 3 . N 2 physisorption and XRD results show the incorporation of phosphorus as phosphate acid enhanced the hydrothermal stability of Cu-SSZ-13 significantly, during hydrothermal aging in 10 vol.% H 2 O/air at 750 °C for 16 h. NMR and Raman results suggest that phosphate ions migrate and coordinate with the framework-bonded Al species, forming a framework silicoaluminophosphate interface, thus impeding further dealumination and structure collapse. Before the hydrothermal aging, the isolated Cu 2+ ions partly interact with the phosphate ions, forming Cu-phosphate species and reducing the SCR performance. Nevertheless, the appropriate content of phosphate ions can prevent the structure collapse caused by the hydrothermal aging, remaining the isolated Cu 2+ ions as well as excellent SCR performance.
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Environmental Progress & Sustainable Energy
·
2022
·Vol. 42
·期 2
·e13998
·
IF 2.824
Gang Liu,Zhitao Han,Jiawei Li,Zhen Wang,Shaosi Cheng,Yubin Liu,Jing Yu,Xinxiang Pan
Since it is difficult to deal with high-concentration nitrates in scrubbed wastewater onboard vessels, the application of traditional wet denitration technology is limited to some extent. Here a novel method for removing pre-oxidized NO x by using Na 2 SO 3 /THS composite solution is proposed with the aim to obtain high NO x absorption efficiency and low nitrate concentration in scrubbed wastewater simultaneously. The effects of Na 2 SO 3 concentration, THS concentration, NO x oxidation degree, coexistence of SO 2 and O 2 in flue gas, initial pH value and temperature of absorption solution on denitration performance were discussed in detail. The results showed Na 2 SO 3 could reduce NO x to nitrate, nitrite, and N 2 . The addition of THS could promote NO x absorption greatly by forming complexes with SO 3 2− . When initial NO x concentration was 1000 ppm with a NO x oxidation degree of 50%, O 2 concentration was 8%, Na 2 SO 3 and THS concentrations were 25 and 20 mmol/L, a NO x absorption efficiency of 87% could be achieved, while nitrate and nitrite concentrations were 32.97 and 14.19 mg/L, respectively.
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CHEMICAL ENGINEERING JOURNAL
·
2023
·
IF 15.1
Yuqing Pan,Na Li,Ke Li,Shiyuan Ran,Chenyang Wu,Qulan Zhou,Jiyuan Liu,Shuzhou Li
The industrial applications of de-NOx require the high activity window of the catalysts to be shifted from high to low temperatures for energy saving. Selective catalytic reduction (SCR) of NOx by CO, as an alternative to NH 3 -SCR, is a promising de-NOx technology that facilitates the synergistic removal of pollutants. Herein, we report a new Fe 2 O 3 /amorphous SiO 2 catalyst with high low-temperature activity for CO-SCR. A combination of experiments and density functional theory (DFT) calculations obtains direct evidence that an optimal content of oxygen vacancy enhances the low-temperature NO conversion ratio and N 2 selectivity of Fe 2 O 3 -based catalyst to over 80% and maintain 100% CO conversion by promoting NN coupling via ONNO/N 2 O and NCO/NNCO 2 intermediates. Compared with conventional defect engineering, such as doping other metals or artificially generating oxygen defects, the α-Fe 2 O 3 (1 1 0) facet automatically enables an oxygen vacancy generation-filling cycle in the CO-SCR reaction, following Mars-van Krevelen (MvK) mechanism. This work advances a fundamental understanding of CO-SCR reaction mechanism over Fe 2 O 3 -based catalysts and provides insights for future studies to improve heterogeneous metal oxide catalysts.
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JOURNAL OF RARE EARTHS
·
2022
·
IF 4.632
Ningyuan Wang,Xiaoqiang Wang,Yue Liu,Zhongbiao Wu
Traditional vanadium-based selective catalytic reduction (SCR) deNO x catalyst can hardly adapt to the gas conditions (much high NO 2 /NO x ratio at lower temperature) of the start-up and low loading periods for a gas turbine . Therefore, a W–Ti-CeO x catalyst with NO x storage and reduction (NSR) function was developed in this work for gas turbine exhaust NO x elimination. The experimental results reveal that W–Ti-CeO x catalyst exhibits high NO 2 adsorption capacity at relatively low temperature while that is quite low for V–W/TiO 2 . The abundant surface Ce 3+ species can be mainly responsible for its high adsorption ability owing to the reaction between NO 2 and Ce 3+ to form nitrate/nitrite species and NO. Meanwhile, the adsorption capacity of W–Ti-CeO x can easily regenerate at medium–high temperature and NH 3 -SCR reaction. Furthermore, W–Ti-CeO x also shows good NH 3 -SCR activity, which can fulfill the deNO x process at high temperature. The addition of W and Ti into ceria can enhance the surface acidity and redox ability, thereby increasing the SCR activity. This work proposes a novel storage-reduction strategy for NO x elimination throughout the operation of gas turbines.
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