APPLIED CATALYSIS B-ENVIRONMENTAL
·
2022
·
IF 24.319
Jun Cai,Yi Xia,Ruiqi Gang,Sufang He,Sridhar Komarneni
Defect engineering and heterogeneous doping are considered as the effective routes to improve the photocatalytic activity of MoS 2 . In this study, tungsten was used to produce sulfur defects and tungsten doping on MoS 2 by one step hydrothermal treatment. Tungsten doping not only promotes the formation of sulfur defects, but also accelerates the efficiency of separation and transfer of electron-hole pairs, which enables the samples to maintain high catalytic oxidation activity for a long time. Furthermore, comparative experiments show that sulfur defects can promote the activation of O 2 and the formation of more active O 2 - and ·OH species. As a result, the W-doped MoS 2 exhibited a high removal efficiency of more than 99% of gaseous mercury. In addition, W-doped MoS 2 showed good stability, long term durability, enhanced water and sulfur resistance under light illumination. This work provides a novel direction for designing efficient photocatalysts based on transition metal dichalcogenides.
研究领域:
材料科学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2019
·
IF 5.128
Shu Yang,Kang Liu,Min Liu,Xu Yan,Cao Liu,Minneng Wen,Hui Liu,Liyuan Chai
Copper sulfate (CuSO 4 ) is a ubiquitous component in natural minerals and industrial dusts. However, CuSO 4 has been believed usually that it has adverse effect on elemental mercury (Hg 0 ) removal from flue gas. Here, we offered a new insight into the effect of crystal water in copper sulfate on Hg 0 catalytic oxidation. The structure evolution of copper sulfate by density functional theory (DFT) calculation revealed anhydrous CuSO 4 crystal contributing to a better HCl adsorption which provided a precondition for Hg 0 oxidation. Experimental results about the catalytic activity sequence of CuSO 4 > CuSO 4 ·H 2 O > CuSO 4 ·5H 2 O with HCl confirmed the negative effect of crystal water on Hg 0 catalytic oxidation. To realize industrial application, supported catalysts CuSO 4 /α-Al 2 O 3 synthesized by wet impregnation method was employed for elemental mercury (Hg 0 ) oxidation and the results exhibited excellent performance in Hg 0 oxidation under 250 °C–400 °C. The Hg 0 conversion efficiency was above 97% in the presence of 2 ppm HCl + 6% O 2 at 300 °C. Combining computational and X-ray photoelectron spectroscopy (XPS) analyses together, Cu atoms exposure on the surface of anhydrous CuSO 4 were the critical active sites for Hg 0 oxidation and the reaction obeyed the Eley–Rideal mechanism.
研究领域:
环境科学
·
化学工程
✓ 已验证
DOI
高影响因子
INTERNATIONAL JOURNAL OF COAL GEOLOGY
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2016
·
IF 3.294
Hailong Li,Lei Zhu,Shaokang Wu,Yang Liu,Kaimin Shih
Synergy for low temperature Hg 0 oxidation under selective catalytic reduction (SCR) atmosphere was achieved when copper oxides and cerium oxides were combined in a CuO-CeO 2 /TiO 2 (CuCeTi) catalyst. Hg 0 oxidation efficiency as high as 99.0% was observed on the CuCeTi catalyst at 200 °C, even the gas hourly space velocity was extremely high. To analyze the synergistic effect , comparisons of catalyst performance in the presence of different SCR reaction gases were systematically conducted over CuO/TiO 2 (CuTi), CeO 2 /TiO 2 (CeTi) and CuCeTi catalysts prepared by sol-gel method. The interactions between copper oxides and cerium oxides in CuCeTi catalyst yielded more surface chemisorbed oxygen, and facilitated the conversion of gas-phase O 2 to surface oxygen, which are favorable for Hg 0 oxidation. Copper oxides in the combination interacted with NO forming more chemisorbed oxygen for Hg 0 oxidation in the absence of gas-phase O 2 . Cerium oxides in the combination promoted Hg 0 oxidation through enhancing the transformations of NO to NO 2 . In the absence of NO, NH 3 exhibited no inhibitive effect on Hg 0 oxidation, because enough Lewis acid sites due to the combination of copper oxides and cerium oxides scavenged the competitive adsorption between NH 3 and Hg 0 . In the presence of NO, although NH 3 lowered Hg 0 oxidation rate through inducing reduction of oxidized mercury, complete recovery of Hg 0 oxidation activity over the CuCeTi catalyst was quickly achieved after cutting off NH 3 . This study revealed the synergistic effect of the combination of copper oxides and cerium oxides on Hg 0 oxidation, and explored the involved mechanisms. Such knowledge would help obtaining maximum Hg 0 oxidation co-benefit from SCR units in coal-fired power plants.
研究领域:
环境科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2023
·
IF 8.6
Linzhi Shen,Ziwen Xiong,Zhaohui Du,Hao Wang,Wenrui Li,Zhen Zhang,Hao Wu,Changsong Zhou,Yaming Zhou,Guanghua Tang,Jing Liu,Hongmin Yang
M-N-C catalysts have considerable potential in the fields of catalysis, such as highly polluting gaseous elemental mercury (Hg 0 ) oxidation. However, the direct application of these kinds of catalysts for mercury removal is stymied by their low catalytic efficiency. Heteroatom-doping in M-N-C catalysts has been proposed as a powerful strategy to the promote catalytic of Hg 0 , but the origin of boosting catalytic activity is still elusive. Herein, it is disclosed that selenium doping induces an obvious electron-acceptor effect for accelerating the Hg 0 catalytic oxidation. The model selenium-doped Cu-N-C catalyst with atomically dispersed active sites was verified by various characterization methods, such as SEM-EDS and scanning transmission electron microscopy. The optimal Cu-NC-Se with Cu/Se ratio of 1:1 exhibited the best Hg 0 removal performance, over 8-fold enhancement in their Hg 0 oxidation capacities than raw selenium-free Cu-NC. At the optimal reaction temperature of 90 °C, Cu-NC-Se achieved an average Hg 0 removal rate of 92.44% within 60 min under single pure N 2 atmosphere. As for the influence of flue gas components, the presence of O 2 promoted the removal of mercury in Cu-NC-Se, whereas CO 2 , NO and SO 2 served as slight inhibitors. Even after five cycles of the experiment, the average mercury oxidization efficiency was still remained at 88.5%, showing that Cu-NC-Se can be reused with good maintenance of the catalytic activity and atomic dispersion of Cu and Se in the structure. The unsaturated Cu sites connected with pyridinic N on the carbon matrix can serve preferential adsorption to Hg 0 and doped selenium. Meanwhile, the selenium doping accelerated Hg 0 adsorption and accept sufficient electrons for promoting Hg 0 oxidation to forming stable HgSe, which is also corroborated by the theoretical analysis results based on density functional theory. This work not only provides an alternative facile synthetic strategy for developing heteroatom-doping atomically dispersed M-N-C catalysts, but also represents a significant advance for deepening the understanding of the Hg 0 catalytic oxidation mechanism on M-N-C catalyst.
研究领域:
催化化学
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环境科学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
·
2019
·Vol. 26
·期 13
·13602-13618
·
IF 2.914
Yue Huifang,Lu Pei,Su Wei,Xing Yi,Li Rui,Wang Jiaqing
To optimize the simultaneous removal of NO x and Hg 0 , a series of Cu a Ce b Zr c O 3 /γ-Al 2 O 3 catalysts prepared by the impregnation method were explored and their physical and chemical properties were analyzed by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) analysis, X-ray photoelectron spectroscopy (XPS), NH 3 -temperature-programmed desorption (NH 3 -TPD), H 2 -temperature-programmed reduction (H 2 -TPR), in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFT), and Fourier transform infrared spectroscopy (FT-IR). The results showed that 15% Cu 1.4 Ce 0.55 Zr 0.25 O 3 /γ-Al 2 O 3 resulted in the highest conversion efficiency for the simultaneous removal of NO x (93%) and Hg 0 (85%) at low temperatures (200 to 300 °C). Meanwhile, 15% Cu 1.4 Ce 0.55 Zr 0.25 O 3 /γ-Al 2 O 3 showed good stability and resistance to SO 2 and H 2 O, which is due to its low crystallinity, good textural performance, and strong redox ability. According to the TPD, TPR, and XPS results, the strong acidic character of 15% Cu 1.4 Ce 0.55 Zr 0.25 O 3 /γ-Al 2 O 3 promoted the removal of NO x and Hg 0 . The synergistic effect between CuO and CeO 2 in 15% Cu 1.4 Ce 0.55 Zr 0.25 O 3 /γ-Al 2 O 3 can increase the mobility of chemically adsorbed oxygen and activates lattice oxygen, leading to an excellent performance. The DRIFT results showed that NH 3 , NH 4 + , nitrate, and nitrite participated in the selective catalytic reduction (SCR) reaction. On the basis of our experimental results, Hg 0 and NO x removal mechanisms were proposed as Hg (ad) + O* → HgO (ad) and 2NH 3 /NH 4 + (ad) + NO 2 /NO 3 − (ad) + NO→2N 2 + 3H 2 O/2H + , respectively.
研究领域:
环境催化
·
大气污染控制
·
材料化学
·
表面科学
·
工业生态学
✓ 已验证
DOI
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2019
·
IF 14.229
Liyuan Zhang,Shu Yang,Yuekun Lai,Hui Liu,Yiang Fan,Cao Liu,Haiying Wang,Liyuan Chai
Gaseous Hg 0 is one of the most deadly and hard-to-dispose pollutants. The oxidation of Hg 0 is a promising route, but the rational design and synthesis of highly efficient catalysts still remain grand challenges. Herein, CuO@Cu 2 O (or Cu x O) heterostructured nanoparticles uniformly monodispersing on porous carbon monolith were designed and successfully synthesized using oligo( m -phenylenediamine)-Cu 2+ complex as raw material. The Cu x O-carbon catalyst contains ∼28 wt% of Cu. Based on density functional theory calculation, the CuO@Cu 2 O junction interfaces can accelerate the Hg 0 oxidation by significantly reducing the energy barriers of reaction. Only 1 mg of the catalyst can catalyze the oxidation of more than 90 % of Hg 0 with [HCl] = 0.5 ppm, [O 2 ] = 6 vol%, T = 150 °C. The poisoning effect of either SO 2 or H 2 O on the catalysts is weak. Moreover, a long-term test confirmed that the Hg 0 oxidation rate can maintain more than 90 % even in the co-presence of SO 2 (5000 ppm) and H 2 O (10 vol%).
研究领域:
环境催化
·
材料化学
·
大气污染控制
·
纳米材料
·
表面科学
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2022
·
IF 16.744
Zhilei Guo,Guohua Jing,Sara A. Tolba,Chung-shin Yuan,Yu-Hua Li,Xiaowei Zhang,Zhiwei Huang,Huawang Zhao,Xiaomin Wu,Huazhen Shen,Wenjie Xia
Transition metal oxide (TMO)-decorated TiO 2 catalysts excel at low-temperature Hg 0 oxidation. However, TMOs are typically found in large nanoparticles (NPs), resulting in a lower atom utilization efficiency. The current paper presents the design of an Au single atom (SA)-doped Ti 4+ defected TiO 2 (Au SAC-Ti 1-x O 2 ) and investigations concerning the influence of an O-Au-O coordination environment on Hg 0 oxidation. Au SAC-Ti 1-x O 2 was designed using an O-Au-O coordination environment and the O-Au-O orbital interaction was elucidated using density functional theory (DFT). The enhanced oxidative capability of lattice oxygen atoms and the interaction between Hg 0 and oxygen atoms were investigated. The O-Au-O coordination environment containing Au SAC Ti 1-x O 2 was then synthesized and characterized using X-ray absorption fine structure (XAFS), X-ray photoelectron spectroscopy (XPS), etc. Finally, Hg 0 oxidation catalytic activity was determined. Due to the increasing population of Au-O antibonding orbital interactions in the valence band, the bond order of O-Au-O in Au SAC Ti 1-x O 2 decreased significantly, thereby enhancing the oxidation ability of its adjacent oxygen atoms. Au SA and ultra-small Au clusters coexisted on a Ti 1-x O 2 catalyst, and the Hg 0 -oxidation efficiency at 150–200 °C was 14 times and 1.5 times greater than those of TiO 2 and 0.1 % Au/TiO 2 , respectively. Furthermore, Au SAC Ti 1-x O 2 was more resistant to the inhibition of SO 2 and NO. It provides an efficient method for developing highly active SA catalysts for Hg 0 oxidation.
研究领域:
催化化学
·
环境科学
·
材料化学
·
理论与计算化学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）