ACS Omega
·
2023
·
IF 4.1
Shasha Huang,Yulong Shan,Xiaoyan Shi,Zhongqi Liu,Qiang Wang,Hong He
In the present work, we report on two passive NOx adsorber (PNA) material candidates: the novel support CeSnOx with and without Pd loading. The NOx adsorption and storage capacities of fresh and hydrothermally aged CeSnOx and Pd/CeSnOx were investigated. The results show that CeSnOx exhibits a rather large NOx uptake and storage capacity (28.9 μmol/g), while the loading of Pd on CeSnOx can further increase the storage capacity to 37.6 μmol/g and affect the desorption temperature of NOx. It was found that the NOx desorption temperature of Pd/CeSnOx was compatible with the efficient operating window of selective catalytic reduction (SCR) catalysts. After a hydrothermal aging treatment at 800 °C for 12 h, the NOx adsorption and storage capacities of CeSnOx and Pd/CeSnOx increased, indicating excellent hydrothermal stability. The interaction of Pd with CeSnOx, the state of Pd species, and the structure of CeSnOx and Pd/CeSnOx are studied by combination of the characterization results.
研究领域:
化学
·
材料科学
·
环境科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
FUEL
·
2023
·
IF 7.4
Yinan Wang,Xuteng Zhao,Ting Chen,Zuwei Zheng,Rijing Zhan,He Lin
Pd/SSZ-13 with different Al distributions were hydrothermally synthesized and utilized as passive NOx adsorbers (PNA). The characterization results indicated that more concentrated Al distribution can not only improve the ion-exchanged level of Pd but also generated more Z 2 Pd 2+ sites at six-member rings. Thus, as revealed by NOx adsorption experiments, samples with more Z 2 Pd 2+ sites showed high NOx storage capacity as well as stronger water resistance. Besides, 84.8 % adsorption capacity of this sample was retained after hydrothermal aging treatment. On the other side, Pd existed as [Pd(OH)] + sites on SSZ-13 with isolated Al as the majority. These sites were vulnerable to H 2 O and less stable. Seriously Pd agglomerated was observed on the aged Pd/SSZ-13 with less paired Al. This study revealed that proper Al distribution on SSZ-13 could significantly improve the performance and stability of the catalyst and provided a new direction for the design of PNA catalysts.
研究领域:
催化化学
·
环境科学
✓ 已验证
DOI
高影响因子
Materials Science and Engineering B-Advanced Functional Solid-State Materials
·
2025
·
IF 4.6
Muhammad Kamran,Muhammad Sajjad,Salman Qadir,Changle Wang,Runtong Zhang,Baode Ma,Shao-Tao Bai
Crystal facet engineering is an important concept in material science but is yet to be explored direction of fabricating catalysts with improved selectivity. In this study, we prepared pure TiO 2 brookite nanorod catalysts exposed with a variation of (120), (111), and (110) active crystal domains for photocatalytic NOx (nitrogen oxides) abatement using TALH (C 6 H 18 N 2 O 8 Ti) titania precursor via a variation of sodium lactate (C 3 H 5 NaO 3 ) and urea (NH 4 CNO) addition. The different characterization such as XRD, SEM, and TEM proved the high availability of (111) crystal facet and approximate equal presence of (120), (111), and (110) crystal domains in TALH-6U-SL resulting in up to 4.9-fold higher selectivity than commercial TiO 2 -P25 as well as other brookite nanorod catalysts. TGA, FTIR, and XPS results demonstrated that compared to other catalysts, TALH-6U-SL nanorod catalyst adsorbs more water and contains more oxygen vacancies and crystal defects, thus boosting the photocatalytic selectivity for NOx conversion to NO 3 − ions.
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
Environmental Technology & Innovation
·
2018
·
IF 0
Jiaorong Yan,Feixiang Zhou,Ying Zhou,Xianghao Wu,Qiulian Zhu,Huayan Liu,Hanfeng Lu
The removal of NO x with low oxidation degree, low temperature, and high vapor content from small coal-fired boiler emission through selective catalytic reduction is difficult. This study investigated liquid oxidation and absorption to remove NO x systematically. Thermodynamic calculation showed that the equilibrium constants of the NO oxidation and NO x absorption reaction are high; thus, NO x treatment by liquid oxidation and absorption is feasible. Four oxidants (NaClO 2 , NaClO, H 2 O 2 , and KMnO 4 ) and four absorbents (Ca(OH) 2 , CaCO 3 , NaOH, and Na 2 CO 3 ) were used to study the reaction mechanism of the oxidation and absorption processes. Results show that NaClO 2 solution is the best oxidant, and the optimum pH value of the oxidation reaction is 5–6. The oxidation degree reaches 100% when the concentration of the NaClO 2 solution is 1.0%, and the oxidation degree can still reach approximately 50% when the concentration is 0.1%. Ca(OH) 2 slurry has the best absorption performance among the four kinds of absorbents. The NO x removal efficiency of Ca(OH) 2 slurry can reach approximately 70% when the oxidation degree is 50%. The removal efficiency is up to 80% when the oxidation degree is 100%.
研究领域:
环境科学
·
化学工程
✓ 已验证
产品关联
DOI
Journal of Environmental Sciences
·
2018
·
IF 3.12
Wen Xie,Yunbo Yu,Hong He
Pt/BaO/Al 2 O 3 catalysts with different BaO loadings prepared from Al 2 O 3 nanorods (Pt/BaO/Al 2 O 3 -nr) and irregular Al 2 O 3 nanoparticles (Pt/BaO/Al 2 O 3 -np) were investigated for NO x storage and reduction (NSR). The Pt/BaO/Al 2 O 3 materials derived from Al 2 O 3 nanorods always exhibited much higher NO x storage capacity (NSC) over the whole temperature range of 100–400°C than the corresponding Pt/BaO/Al 2 O 3 -np samples containing the same BaO loading, giving the maximum NSC value of 966.9 μmol/g cat at 400°C, 1.4 times higher than that of Pt/BaO/Al 2 O 3 -np. Higher catalytic performance of nanorod-supported NSR samples was also observed during lean-rich cyclic conditions (90 sec vs. 5 sec), giving more than 98% NO x conversion at 300–450°C over the Pt/BaO/Al 2 O 3 -nr sample with 15% BaO loading. To reveal this dependence on the shape of the support during the NSR process, a series of characterization techniques including the Brunauer–Emmett–Teller (BET) method, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), H 2 temperature programmed reduction (H 2 -TPR), and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) were also conducted. It was found that intimate contact of Ba–Al and Ba–Pt sites was achieved over the Pt/BaO/Al 2 O 3 surface when using Al 2 O 3 -nr as a support. This strong interaction among the multi-components of Pt/BaO/Al 2 O 3 -nr thus triggered the formation of surface nitrite and nitrate during the lean period, and also accelerated the reverse spillover of ad-NO x species onto the Pt surface, enhancing their reduction and leading to high NSR performance.
研究领域:
催化化学
·
环境催化
·
材料科学
·
能源与环境工程
·
多相催化
✓ 已验证
DOI
高影响因子
ACS Omega
·
2020
·
IF 2.87
Jiashan Chen,Ge Pu,Jian Li
xMo/TiO2 catalysts (x = 1, 2, 3, and 4%) were prepared using the coprecipitation method in the present study. The coprecipitation method was used in the thermal catalytic decomposition of H2O2 steam to treat NOx at a low temperature range (80–160 °C). Several characterization techniques have been employed, such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller measurements, transmission electron microscopy (TEM), scanning electron microscopy and energy-dispersive X-ray spectrometry (SEM–EDXS), and Fourier transform infrared spectroscopy. The activity tests showed that the incorporation of molybdenum into TiO2 led to a significant increase in the catalytic oxidation of NO, and under the condition of H2O2/NO = 6:1 (molar ratio), the NOx removal rate of 2% Mo/TiO2 is the highest, reaching 92.56%. XRD, TEM, and SEM–EDXS analyses showed that Mo was well dispersed on the surface of an anatase-phase TiO2. XPS analysis indicated that Mo mixed with slag mainly existed in the form of Mo6+. Moreover, in comparison with the mostly reported SCO catalysts, used for the elimination of NO, the prepared Mo/TiO2 catalyst showed excellent stability and sulfur resistance.
研究领域:
环境科学
·
催化化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2025
·
IF 13.2
Changcheng Sun,Lyumeng Ye,Peng Lu,Xianhui Yan,Jianhang Huang,Zhixiong Tang,Dongyao Chen,Chaoping Cen
The key point to broaden the operating temperature window for synergistic control of NO x and oxygenated volatile organic compounds (OVOCs) with high NO x /VOCs conversion and N 2 /CO 2 selectivity relies on development of appropriate catalysts. Herein, a silver-modified Mn/HZSM-5 catalyst was designed, which achieved an effective NO x and acetone co-removal activity and maintained over 90 % N 2 /CO 2 selectivity at a broad temperature range from 293 to 400 °C. The excellent performance of MnAg/HZSM-5 was due to large surface area, plenty of oxygen vacancies and Lewis acid sites, as well as outstanding oxygen mobility and reducibility that derived from the interactions between Mn 4+ /Mn 3+ and Ag + /Ag 0 . NO x reduction followed both Eley-Rideal and Langmuir-Hinshelwood mechanisms, while acetone hardly replaced NH 3 as a reduction agent. Acetone oxidation underwent acetone → acetate → formate → carbonate → CO 2 and H 2 O following a Mars-van Krevelen mechanism. NH 3 participated in acetone oxidation, forming amide and nitrile species, which caused catalyst deactivation and secondary pollution.
研究领域:
环境科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2024
·
IF 8.1
He Ma,Dashuai Li,Yingying Li,Yuanyuan Li,Changhua Wang,Xintong Zhang
While photocatalytic technology has been recognized as an effective means for removing low-concentration NOx in ambient atmosphere, it still faces the challenge of the deep oxidation in high efficiency. In many cases, the release of more toxic NO 2 byproduct appeared to be inevitable during the photocatalytic oxidation of NO. Herein we report that the atomically dispersed MnO x cocatalyst on TiO 2 (B) microspheres could significantly enhance the deep oxidation of NOx under mild photocatalytic conditions (1 mW/cm 2 UV-A light, 1 L/min flow rate). At an initial NO concentration of 0.35 ppm, ca. 67.15% of NO is oxidized on the MT-0.5 sample, which is 2.76 times higher than the pristine TiO 2 (B) sample. More importantly, the release of NO 2 is suppressed by 2.11 times. Comprehensive spectral analyses suggest that atomically dispersed MnO x effectively promotes the charge separation of photogenerated carriers in TiO 2 (B), even better than MnO x nanoparticles-loaded TiO 2 (B). EPR and in-situ FTIR analyses illustrate that atomically dispersed MnO x -loaded TiO 2 (B) sample exhibits excellent low concentration NOx abatement performance, thus providing a rational mechanism for the NO deep oxidation pathway. This study not only provides a unique approach for preparing non-noble metal atomically dispersed co-catalysts, but also affords an effective means for efficient photocatalytic NO degradation.
研究领域:
环境科学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
·
2022
·
IF 14.224
Wen Xie,Guangyan Xu,Yan Zhang,Yunbo Yu,Hong He
A mesoporous LaCoO 3 perovskite oxide (LaCoO 3 -Meso) with three-dimensionally ordered helical interwoven structure was synthesized by a nano-casting method using KIT-6 as the hard template. The obtained LaCoO 3 -Meso with high surface area was tested for its catalytic performance in the NO x storage and reduction (NSR) reaction and compared with a sample synthesized by the conventional sol-gel method. The LaCoO 3 -Meso showed a significant advantage for NO x storage, with a NO x storage capacity 2 times higher than the regular sample. LaCoO 3 -Meso also exhibited improved NSR catalytic performance in the 150–450 °C temperature range, especially within 350–400 °C, where the NO x conversion was raised for 40%. The results of X-ray photoelectron spectroscopy and X-ray absorption fine structure measurements suggested the presence of a high concentration of oxygen defects on the LaCoO 3 -Meso surface. Further results provided by temperature programmed reduction and temperature programmed desorption indicated that the oxygen defects not only increase the amount of trapped NO x , but also improve the low-temperature redox performance of the catalyst. The lower stability of NO x species adsorbed on oxygen defects promotes the NO x release step in the NSR reaction and benefits the regeneration of storage sites.
研究领域:
材料科学
·
环境科学
·
化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
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.
研究领域:
环境工程
·
催化
·
能源工程
✓ 已验证
产品关联
DOI
高影响因子
RSC Advances
·
2018
·Vol. 8
·期 11
·6110-6119
·
IF 2.936
Chengkai Pang,Yuqun Zhuo,Qiyu Weng,Zhenwu Zhu
The activity and hydrothermal stability of Cu/SAPO and xMn–2Cu/SAPO for low-temperature selective catalytic reduction of NOx with ammonia were investigated. An ion-exchanged method was employed to synthesize xMn–2Cu/SAPO, which was characterized by N2 adsorption, ICP-AES, X-ray diffraction (XRD), NH3-temperature programmed desorption (NH3-TPD), NO oxidation, X-ray photoelectron spectrum (XPS), UV-vis, H2-temperature programmed reduction (H2-TPR) and diffuse reflectance infrared Fourier transform spectra (DRIFTS). 2Mn–2Cu/SAPO and 4Mn–2Cu/SAPO showed the best SCR activity, in that at 150 °C NO conversion reached 76% and N2 selectivity was above 95% for the samples. NO oxidation results showed that the 2Mn–2Cu/SAPO had the best NO oxidation activity and the BET surface area decreased as manganese loading increased. XRD results showed that the metal species was well dispersed. NH3-TPD showed that the acid sites have no significant influence on the SCR activity of xMn–2Cu/SAPO. H2-TPR patterns showed good redox capacity for xMn–2Cu/SAPO. UV-vis and H2-TPR showed that the ratio of Mn4+ to Mn3+ increased as manganese loading increased. XPS spectra showed a significant amount of Mn3+ and Mn4+ species on the surface and addition of manganese increased the ratio of Cu2+. The promotion effect of manganese to 2Cu/SAPO comes from the generation of Mn3+ and Mn4+ species. Deduced from the DRIFTS spectra, the Elay–Rideal mechanism was effective on 4Mn–2Cu/SAPO.
研究领域:
环境科学
·
催化化学
✓ 已验证
DOI
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2014
·
IF 6.007
Jun Yu,Zhichun Si,Lei Chen,Xiaodong Wu,Duan Weng
A zirconium phosphate @ Ce 0.75 Zr 0.25 O 2 (ZP/CZ) catalyst was synthesized by impregnating zirconium phosphates on Ce 0.75 Zr 0.25 O 2 microspheres. Catalysts with different structures were also synthesized by various methods to illustrate the structure advantage of ZP/CZ catalyst in selective catalytic reduction of NO x by ammonia (NH 3 -SCR). The catalysts were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), BET surface area, Infrared (IR) spectra, Ultraviolet-visible (UV–vis) spectroscopy, X-ray photoelectron spectroscopy (XPS), H 2 -temperature programmed reduction (TPR) and diffuse reflectance infrared Fourier transformed spectra (DRIFTS) of NH 3 /NO x adsorption. ZP/CZ catalyst presents excellent catalytic activity at 250–450 °C with a good N 2 selectivity under high space velocity of 300,000 h −1 . Firstly, the zirconium phosphate provides adsorption sites for ammonia on the surface of the catalyst and the cerium sites in the core act as the redox sites for NO oxidation. The pre-combination of zirconium and phosphate can reduce the strong interactions between phosphates and cerium ions. Therefore, the mobility of surface lattice oxygen on Ce 0.75 Zr 0.25 O 2 catalyst is retained, which is essential to obtain a catalyst with high NH 3 -SCR activity at low temperatures. Moreover, NH 4 NO 3 has proved to be an important intermediate for the NH 3 -SCR reaction on the surface of ceria based catalysts. The ZP/CZ catalyst preserves plenty of oxygen vacancies, facilitating the Ce 4+ → Ce 3+ redox circles and therefore promotes the nitrites/nitrates formation and desorption on catalyst. Two distinct adsorption sites for NH 3 and NO x result in a close contact between ads-NH 3 /NH 4 + and ads-NO 3 − /NO 2 − species on ZP/CZ catalyst, which can react with NO rapidly with the participation of active surface lattice oxygen.
研究领域:
环境科学
·
催化化学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）