ENERGY & FUELS
·
2024
·
IF 5.2
Wenbo Jia,Yueyuan Wang,Shaohua Ling,Liren He,Binghe Chen,Songtao Liu,Chuanmin Chen,Yue Cao
Fast selective catalytic reduction (SCR) atmosphere can significantly improve the NOx removal activity of VWTi catalysts, while the catalytic performance and reaction pathway of Hg0 oxidation in a fast SCR atmosphere are still unclear. In this paper, the catalytic activity of simultaneous NOx removal and Hg0 oxidation over VWTi catalysts in a simulated fast SCR atmosphere was investigated for the first time. The results showed that VWTi catalysts possessed a wide NOx removal active temperature window and a high Hg0 oxidation activity in a fast SCR atmosphere. The X-ray photoelectron spectroscopy (XPS) and Hg temperature-programmed desorption (Hg-TPD) methods were used to investigate the Hg0 oxidation process over VWTi catalysts in a fast SCR atmosphere. Combined with the homogeneous Hg0 oxidation experiment results, two domination reaction routes of Hg0 oxidation over VWTi catalysts in a fast SCR atmosphere were proposed. One was that the adsorbed Hg0 could react with the surface active species to form HgO. The other reaction route was a gaseous homogeneous route that the gaseous Hg0 could be oxidized directly to Hg(NO3)2 by gaseous NO2. Particularly, the gaseous homogeneous Hg0 oxidation process could notably weaken the inhibition effect of NH3 on Hg0 oxidation, thus improving the Hg0 oxidation activity of VWTi catalysts in a fast SCR atmosphere.
研究领域:
环境科学
·
催化化学
✓ 已验证
DOI
高影响因子
Journal of Environmental Chemical Engineering
·
2023
·
IF 7.7
Chenhui Hu,Chunhong Liu,Kaimin Du,Chengkai Pang,Zuoxi Zhuo,Qiangsheng Gao
An energy-saving catalyst 4%Fe/Ce-Mn-TiO 2 was prepared via a simple one-step impregnation-annealing process and used as a denitration catalyst at low temperature (≤180 °C) and high water content (∼20%). The results show that 4%Fe/Ce-Mn-TiO 2 catalyst exhibits good low-temperature catalytic activity and water resistance attributed to its highly dispersed metal oxide species, more surface-adsorbed oxygen and high stability of particles. The denitrification efficiencies of 4%Fe/Ce-Mn-TiO 2 catalyst are 90% (5% H 2 O) and 70% (20% H 2 O) at 170 ℃ respectively, which are superior to the commercial vanadium catalyst in service usually needs heating up to 220 ℃.
研究领域:
环境科学
·
催化
·
化学工程
✓ 已验证
DOI
高影响因子
Catalysis Science & Technology
·
2023
·Vol. 13
·期 18
·5435-5448
·
IF 5
Xinyue Hu,Jialing Chen,Shaokang He,Tingyu Liang,Shenke Zheng,Lijun Lu,Chenxi Hao,Kaixin Chen,Tingting Li,Lan Yi,Li Guo,Xiaoqin Wu
Three OP-Fe-FER-x zeolites (with an FER structure) synthesized by a one-pot method with different Si/Al ratios (x = Si/Al =10–30) and similar iron contents (5.4–5.6 wt%) were compared with commercial IM-Fe/SSZ-20 zeolite (with a CHA structure) prepared by an incipient wetness impregnation method to investigate their catalytic activity and hydrothermal stability for the selective catalytic reduction reaction of NOx with NH3 (NH3-SCR). For both fresh (without hydrothermal aging treatments) and aged (with hydrothermal aging treatments) zeolites, the NOx conversions of OP-Fe-FER-x zeolites are much higher than that of IM-Fe/SSZ-20 zeolite, suggesting that the OP-Fe-FER-x zeolites are better catalysts for NH3-SCR than the commercial IM-Fe/SSZ-20 zeolite. Compared with the fresh zeolites, the NOx conversions of all four aged zeolites decrease in the low-temperature range (100–300 °C), while they increase at high temperatures (450–550 °C) to different extents. Based on XRD, N2 physisorption, NH3-TPD, UV-vis, XPS and H2-TPR experiments, the hydrothermal aging process of the OP-Fe-FER-x zeolites is depicted, which consists of partial collapse of the zeolite framework, removal of framework aluminum and iron atoms, and transformation and aggregation of iron species. Detailed characterization reveals that the OP-Fe-FER-x zeolites are more stable than the IM-Fe/SSZ-20 zeolite during the hydrothermal aging treatments. The obvious decline of NH3-SCR catalytic activity for the aged zeolites in the low-temperature range is mainly attributed to the transformation and aggregation behaviors of active isolated Fe3+ species. As for the increase of NH3-SCR activity for the aged zeolites at the high temperatures (450–550 °C), it is mainly attributed to the suppression of the NH3 oxidation side reaction due to the deteriorated NH3 storage capacity because of the loss of massive acid sites during the hydrothermal aging treatments.
研究领域:
化学工程
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING SCIENCE
·
2022
·
IF 4.889
Wuyuan Liu,Zihan Gao,Ming Sun,Jiajian Gao,Lifeng Wang,Xiangyun Zhao,Runnong Yang,Lin Yu
A series of Cr α Mn β CeTiO x catalysts were prepared using one-pot precipitation method and evaluated for the selective catalytic reduction (SCR) of NO with ammonia. Among the catalysts prepared, the Cr 0.006 Mn 0.05 CeTiO x catalyst exhibited the highest low-temperature activity and widest activity window (＞90% NO conversion at 160–425 °C) as well as outstanding sulfur resistance. The catalysts were characterized using XRD, NH 3 /NO/SO 2 + O 2 -TPD, XPS, in situ DRIFT, and so on. The amorphous Cr 0.006 Mn 0.05 CeTiO x catalyst had a larger specific surface area, high ammonia adsorption and strong acidity, resulting in an improved catalytic activity. A high ratio of surface adsorption oxygen and Ce 3+ promoted the formation of NO 2 , a key intermediate gas in the fast SCR reaction. Furthermore, in situ DRIFT showed that the SCR reaction followed the Eley Rideal and Langmuir Hinshelwood mechanisms. Moreover, the synergetic effect of Cr and Mn inhibited the accumulation of hydrogen sulfate or sulfate considerably.
研究领域:
催化化学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
CATALYSIS LETTERS
·
2023
·
IF 2.8
Wang Yanghui,Jin Luyao,Xu Xintao,Li Jiaying,Fan Kaihao,Hu Bo,Shen Yi,Liu Xuesong
In this paper, MnO x /TiO 2 catalysts with different manganese contents were prepared by using vacuum over-impregnation method to support manganese on TiO 2 support. However, the activity temperature window was narrow and the denitrification efficiency was only 265–365 °C in the temperature zone above 80%. Therefore, doping W was used to improve the high temperature activity and broaden the activity temperature window. The experimental results show that the active temperature window of the catalyst is expanded to 260–550 °C when doping 20%WO 3 . The effects of tungsten doping on the structure and surface properties of the catalysts were investigated by XRD, TEM, Raman, XPS, H 2 -TPR and NH 3 -TPD. It is found that the increase of manganese content would increase the ratio of Mn 4+ and O α , and then improve the NH 3 -SCR activity at low temperature. Tungsten doping can provide more strong acid sites and improve the high temperature activity of the catalyst by inhibiting the oxidation of ammonia. Graphical Abstract
研究领域:
催化化学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Physical Chemistry C
·
2024
·
IF 3.3
Fumei Wang,Qi Cai,Xinhua He,Boxiong Shen,Leila Negahdar,Shuo Feng,Andrew M. Beale
Cu/SAPO-34 catalysts have been widely used for the reduction of NOx from diesel exhaust by ammonia-selective catalytic reduction (SCR). Sulfur poisoning remains a challenge for Cu/SAPO-34 catalysts in NH3–SCR, restricting its application. In this study, Cu/SAPO-34 samples containing a mixture of Cu species comprising isolated Cu2+ located in the 6MR, Cu(OH)+ in 8MR, CuO clusters/nanoparticles, and Cu+ species were prepared. The Cu speciation during SO2 and hydrothermal aging of Cu/SAPO-34 SCR catalysts was subsequently studied. While hydrothermal aging had little effect on catalytic activity, the sulfur-aged sample exhibited deterioration in NH3–SCR activity over the temperature range of 100–575 °C. The breakage and collapse of the zeotype framework and chemical deactivation of the Cu/SAPO-34 catalyst after exposure to SO2 and H2O took place. A combination of X-ray photoelectron spectroscopy (XPS) and TGA-DT-DSC revealed the presence of ammonium bisulfate, copper bisulfate/sulfate, aluminum sulfate, and sulfuric acid after SO2 and H2O copoisoning under SCR conditions. Furthermore, Cu(OH)+ tended to migrate to form isolated Cu2+ and Cu+, as well as agglomerate to form CuO particles. Density functional theory (DFT) calculations revealed that SO2 and O2 could readily be absorbed by CuO particles to form stable copper bisulfate/sulfate species with the following order of preference: CuO > Cu+ > Cu2+ > Cu(OH)+. In contrast, Cu(OH)+ was less prone to be poisoned by easily releasing SO3 than other Cu species sites.
研究领域:
环境科学
·
催化化学
✓ 已验证
DOI
高影响因子
APPLIED SURFACE SCIENCE
·
2022
·
IF 7.392
Yang Gao,Xiaodong Wu,Rui Ran,Zhichun Si,Ziran Ma,Baodong Wang,Duan Weng
Monometallic (V/TiO 2 and Mo/TiO 2 ) and bimetallic (V-Mo/TiO 2 ) catalysts were prepared for selective catalytic reduction (SCR) of NO x with NH 3 at low temperatures (100–300 °C). The effect of MoO x on the dispersion of vanadia with different V 2 O 5 loadings was investigated on the basis of X-ray diffraction (XRD), inductively coupled plasma optical emission spectrometry (ICP-OES), N 2 adsorption–desorption, Raman spectroscopy, ultraviolet–visible (UV–Vis) spectroscopy, X-ray photoelectron spectroscopy (XPS), H 2 temperature-programmed reduction (H 2 -TPR) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). As the molybdenum precursor, NH 4 Mo 7 O 24 increased the solution acidity and promoted polymerization of VO x in liquid phase. At a low vanadia loading, polymerization of VO x , the adsorption rate of NH 3 and transformation of active intermediate species NH 2 were enhanced by adding MoO x , while at a high vanadia loading, the steric hindrance became dominant leading to the formation of crystalline V 2 O 5 and MoO 3 and caused decline in SCR activity.
研究领域:
化学工程
·
环境科学
·
催化材料
✓ 已验证
产品关联
DOI
高影响因子
RESEARCH ON CHEMICAL INTERMEDIATES
·
2018
·Vol. 44
·期 5
·3455-3474
·
IF 1.674
Sun Xiao,Guo Rui-tang,Li Ming-yuan,Sun Peng,Pan Wei-guo,Liu Shu-ming,Liu Jian,Liu Shuai-wei
Fe was used as the modifier to improve the performance of CeZr 2 O
x
catalyst for the selective catalytic reduction (SCR) reaction with ammonia. Experimental results revealed that proper Fe species (Fe/Ce molar ratio = 2) could effectively improve the SCR activity of CeZr 2 O
x
, along with the elevated resistance to SO 2 and H 2 O. The characterization results including BET, XRD, H 2 -TPR and NH 3 -TPD confirmed that Fe species in Fe 2 CeZr 2 O
x
catalyst could inhibit the formation of ZrO 2 crystals and lead to higher reducibility and surface acidity. In addition, more Ce 3+ and surface active oxygen species could be detected on Fe 2 CeZr 2 O
x
compared with CeZr 2 O
x
. By means of in situ DRIFT technique, it could be deduced that the SCR reaction process over Fe 2 CeZr 2 O
x
was accelerated mainly through theL–H pathway due to the advanced adsorption of NH 3 and NO
x
species, along with the promoted NO conversion to NO 2 . Therefore, the modification of CeZrO
x
catalyst by Fe had a significant stimulation effect on its low-temperature SCR performance.
研究领域:
催化化学
·
环境科学
✓ 已验证
DOI
高影响因子
JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2022
·
IF 9.965
Guozhen Qin,Jianfeng Zheng,Yifan Li,Yatao Yang,Xingmin Liu,Xiaojin Han,Zhanggen Huang
Mainly exposed crystal facets and controllable morphology play a key role in the final performance of the preparation of specific nanomaterials . In the present study, a metal–organic framework pyrolysis method without adding solvent modifiers was developed. By adding CO in the calcination atmosphere to change atmosphere ratio, Fe 3 O 4 nanostructures are exposed with different crystal planes and evaluated their performance in NH 3 -SCR reaction. This study proves that SCR catalytic activity of Fe 3 O 4 nanocrystals is dependent on morphology and crystal facet. Compared with materials exposed (1 0 0), catalysts with more (1 1 1) show stronger deNO x performance. The preferential exposure of Fe 3 O 4 (1 1 1) crystal facets increases the concentration of adsorbed oxygen on the catalyst, showing higher surface acidity , and enhances the interaction among NO, O 2 and catalyst, which is conducive to SCR reaction. This is supported by DFT calculations . The results present a great application prospect in preparing nanomaterials with specific crystal structures to effectively treat pollutants.
研究领域:
材料科学
·
环境科学
✓ 已验证
DOI
高影响因子
Catalysis Science & Technology
·
2024
·Vol. 14
·期 10
·2929-2939
·
IF 4.4
Qian Xu,Zhihong Zheng,Jinjing Luo,Zheng Lai,Jianwen Chen,Jiaxin Shang
Supported MnFeOx catalysts have been prepared using Al2O3 as the substrate and were investigated for NH3-SCR. The 20% MnFe/Al2O3 catalyst removed over 80% of NOx with an N2 selectivity exceeding 90% at temperatures between 80 and 340 °C. The results from the various characterization studies indicated that the increased activity of MnFe/Al2O3 catalysts can be primarily linked to the increased chemisorbed oxygen species and Fe3+ concentrations, greater reducibility, and higher adsorption capacity for NH3. These characteristics are the outcome of the strong interaction, larger specific surface, and abundant acidic sites. Additionally, in situ DRIFTS analysis of the reaction mechanism revealed that the E–R and L–H mechanisms were responsible for the NH3-SCR reaction over the 20% MnFe/Al2O3 catalyst.
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
CHEMICAL ENGINEERING JOURNAL
·
2018
·
IF 6.735
Chuanzhi Sun,Hao Liu,Wei Chen,Dezhan Chen,Shuohan Yu,Annai Liu,Lin Dong,Shuai Feng
A series of Sm- and/or Zr-doped MnO x -TiO 2 catalysts were prepared, and the catalysts exhibited better N 2 selectivity and SO 2 resistance than the undoped MnO x -TiO 2 catalyst for the selective catalytic reduction of NO by NH 3 (NH 3 -SCR). The reasons for the good N 2 selectivity and SO 2 resistance of the catalysts were proposed. X-ray photoelectron spectroscopy (XPS) combined with density functional theory (DFT) calculations suggested that electron transfer between the manganese and samarium species by Mn 4+ + Sm 2+ ↔ Mn 3+ + Sm 3+ redox cycles occurred in the Sm-containing catalysts. Furthermore, electron transfer from Sm 2+ to Mn 4+ suppressed electron transfer from NH 3 to Mn 4+ , inhibiting the formation of NH 2 or NH. Thus, the pathway for NH generation was removed, and the reaction of 2NH + 4NO → 3N 2 O + H 2 O was prevented. Consequently, the N 2 selectivity of the NH 3 -SCR reaction was enhanced. In situ diffused reflectance infrared Fourier transform spectroscopy ( in situ DRIFTS) combined with thermogravimetry, differential scanning calorimetry and mass spectrometry (TG-DSC-MS) results revealed that the deposition rate of sulfate species decreases after Sm doping, which was also attributed to the suppressed electron transfer from SO 2 to Mn 4+ , i.e., the oxidation of SO 2 to SO 3 . Thus, the catalysts exhibited better SO 2 resistance.
研究领域:
催化化学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
ChemNanoMat
·
2023
·Vol. 9
·期 11
·e202300407
·
IF 3.8
Xinyu Han,Mengyao Bian,Kaijie Liu,Xin Yang,Daying Zheng,Xiangguang Yang,Yibo Zhang
Graphical Schematic diagram of the dominant mechanism of NH 3 -SCR reaction on CeCu/MCM-49 catalyst before and after poisoning. The L−H mechanism was dominant before poisoning. However, after alkali metal poisoning, NO x adsorption on the catalyst is inhibited, so the E−R mechanism dominates. NO x is a common atmospheric pollutant, and NH 3 -SCR technology efficiently purifies it. CeCuO x binary-oxide nanoparticles were synthesized and loaded onto acid MCM-49 molecular sieve with a large specific surface area to increase acid sites and disperse active sites of the catalyst. The optimized 35 % CeCu/MCM-49 catalyst effectively purified over 80 % of NO x in the temperature range of 200–500 °C and demonstrated excellent resistance to alkali metals, such as K, Na, and Ca. Even after K poisoning, it still removed over 80 % of NO x in the range of 200–450 °C. Various characterization methods, including XRD, FT-IR, TEM, and N 2 isotherm adsorption-desorption tests, confirmed the structure of the catalyst remained intact after poisoning with no substance change, nor agglomeration of nanoparticles. NH 3 -TPD and H 2 -TPR confirmed that the catalyst had effective acidity and redox capacity that were not affected by alkali metals. In-situ DRIFTs showed that the catalytic reaction predominant mechanism shifted from L−H to E−R mechanism after poisoning. This study provides valuable insights into the development of high-performance Ce-based NH 3 -SCR catalysts with alkali metal resistance.
研究领域:
催化
·
环境科学
·
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）