Molecular Catalysis
·
2020
·
IF 3.687
Yiqing Zeng,Zihua Wu,Lina Guo,Yanan Wang,Shule Zhang,Qin Zhong
The problems of easily inactivated by SO 2 poisoning and high N 2 O formation for MnO x based catalysts hinder its application in selective catalytic reduction (SCR) of NO x with NH 3 . The SO 2 poisoning mechanism has been well demonstrated, but the N 2 O formation mechanism was still controversial due to previous limited study. Herein, MnO 2 supported on MO x (Mn/M, M = Al, Si and Ti) were prepared by wet impregnation method to investigate the carrier effect on the formation of N 2 O. Although all of selected supports had a large amount of surface acid sites, only forming strong active-support interaction can separate the activation sites of NH 3 and NO + O 2 . Accordingly, the activation of NH 3 and NO + O 2 on MnTi was respectively occurred on TiO 2 and MnO 2 , but both NH 3 and NO + O 2 was activated on MnO 2 over MnAl and MnSi samples. The over-activation (NH 2 dissociated into NH) of NH 3 would be effectively inhibited when NH 3 activation was occurred on TiO 2 , thus it can significantly suppress the formation of N 2 O. In contrast, the NH 3 species would sharply decompose into NH on MnO 2 and then lead to the high amount of N 2 O. Finally, we proposed some methods that might effectively improve the selectivity of MnO x- based catalysts.
研究领域:
环境科学
·
催化化学
✓ 已验证
DOI
高影响因子
CHINESE JOURNAL OF CATALYSIS
·
2015
·
IF 1.964
Xin Zhao,Lei Huang,Hongrui Li,Hang Hu,Jin Han,Liyi Shi,Dengsong Zhang
Different transition metals were used to modify V 2 O 5 -based catalysts (M-V, M = Cu, Fe, Mn, Co) on TiO 2 via impregnation, for the selective reduction of NO with NH 3 . The introduced metals induced high dispersion in the vanadium species and the formation of vanadates on the TiO 2 support, and increased the amount of surface acid sites and the strength of these acids. The strong acid sites might be responsible for the high N 2 selectivity at higher temperatures. Among these catalysts, Cu-V/TiO 2 showed the highest activity and N 2 selectivity at 225–375 °C. The results of X-ray photoelectron spectroscopy, NH 3 -temperature-programmed desorption, and in-situ diffuse reflectance infrared Fourier transform spectroscopy suggested that the improved performance was probably due to more active surface oxygen species and increased strong surface acid sites. The outstanding activity, stability, and SO 2 /H 2 O durability of Cu-V/TiO 2 make it a candidate to be a NO x removal catalyst for stationary flue gas.
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 MATERIALS SCIENCE & TECHNOLOGY
·
2024
·
IF 11.2
Chi Cao,Jinshuo Li,Linfeng Zhang,Yang Hu,Lin Zhang,Wensheng Yang
Herein, a new type of two-dimensional (2D)/2D Ti 3 C 2 /TiO 2 heterojunction was developed for efficient photocatalytic nitrogen reduction reaction (NRR), in which TiO 2 nanosheets (TiO 2 Ns) were designed as the main catalyst, while Ti 3 C 2 MXene served as the co-catalyst. Experimental and theoretical results revealed that Ti 3 C 2 MXene introduced electron-rich unsaturated Ti sites, serving as highly active sites for both the adsorption and activation of N 2 on the Ti 3 C 2 /TiO 2 heterojunction. Furthermore, the 2D/2D Ti 3 C 2 /TiO 2 heterostructure greatly promoted the directional separation and transfer of charge carriers, facilitated by the internal electric field. This structural feature enabled the spatial separation of the N 2 reduction and H 2 O oxidation half-reactions on the distinct surfaces of Ti 3 C 2 (001) and TiO 2 (001), consequently reducing the reaction energy barrier for each respective process. The synergistic effects arising from the interface and surface interactions within the heterojunction conspicuously improved the photocatalytic NRR activity. As a result, the optimized Ti 3 C 2 /TiO 2 heterojunction exhibited a high NH 3 production rate of 24.4 μmol g -1 h -1 in the absence of sacrificial agents, representing a remarkable 12.8-fold increase compared to individual TiO 2 Ns. This work provides new insights into rational design of high-performance heterogeneous photocatalysts and offers a deeper understanding of the mechanism underlying surface active sites in the photocatalytic NRR process.
研究领域:
材料科学
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催化化学
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环境科学
✓ 已验证
产品关联
DOI
高影响因子
Catalysis Science & Technology
·
2022
·Vol. 12
·期 4
·1245-1256
·
IF 6.177
Jie Yang,Shan Ren,Mingming Wang,Zhichao Chen,Lin Chen,Lian Liu
Ce–Ti catalysts were considered as a promising replacement for V–Ti based catalysts for selective catalytic reduction (SCR) of nitrogen oxides (NO and NO2) with NH3. In this work, a CeO2/TiO2 catalyst was prepared by the impregnation method and studied by a series of in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) experiments. The results showed that CeO2 particles grew along TiO2 faces and amorphous cerium in the lattice of TiO2, both of which are present on the CeO2/TiO2 catalyst. NH4+ might adsorb on the Ti–O–Ce structures or TiO2–CeO2 interface as Brønsted acid sites, while two types of NH4+ species were distinguished by the time-resolved spectroscopic method due to the different increasing trends. Based on the temporal evolution transient in situ DRIFTS spectra, L-NH3 had higher activity than coordinated NH3 species, which suggested that gas phase NO reacted preferentially with L-NH3. The NH4NO3 intermediate dominated the SCR reactions over the CeO2/TiO2 catalyst, which followed the Eley–Rideal mechanism.
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 COLLOID AND INTERFACE SCIENCE
·
2018
·
IF 5.091
Yiqing Zeng,Yanan Wang,Shule Zhang,Qin Zhong,Weilong Rong,Xiaohai Li
In this work, novel (CeO 2 ) x -(CePO 4 ) 1−x (defined as Ce x P 1−x ) nanorod composites were prepared by a simple co-precipitation method, and the influence of CeO 2 on the catalytic performance of CePO 4 for selective catalytic reduction of NO by NH 3 (NH 3 -SCR of NO) was investigated. The catalytic performance evaluation revealed that the Ce x P 1−x catalysts, especially Ce 0.2 P 0.8 exhibited a much better catalytic activity and H 2 O + SO 2 resistance than CePO 4 . Structure characterizations via high-resolution transmission electron microscope (HRTEM) and Brunauer-Emmett-Teller (BET) revealed that the introduction of CeO 2 had a little effect on the shape of CePO 4 nanorods and it could promote the formation of new mesoporous then significantly enhance the surface area of catalyst. The analysis results of active sites suggested that phosphorus was the main adsorption site for NH 3 and the redox sites were controlled by CeO 2 on Ce x P 1−x catalysts. Finally, reaction process study demonstrated that the NH 3 -SCR over Ce x P 1−x was processed via Langmuir-Hinshelwood (L-H) mechanism. Combining the results of active sites and reaction mechanism analysis, it was drawn that the superior low temperature activity of Ce x P 1−x could be attributed to its excellent redox properties, which promoted the oxidation of NO then facilitated the process of NH 3 -SCR via “fast SCR”.
研究领域:
材料科学
·
催化化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
APPLIED CATALYSIS A-GENERAL
·
2017
·
IF 4.339
Baohuai Zhao,Rui Ran,Xingguo Guo,Li Cao,Tengfei Xu,Ze Chen,Xiaodong Wu,Zhichun Si,Duan Weng
Mn/Ce/Ti and Mn/Ce/Nb/Ti catalysts were synthesized using a precipitation method and their catalytic activities for NO selective reduction with NH 3 at low temperatures were evaluated. Nb doping not only improved the activity of the catalyst over a wide temperature range but also restricted the generation of NO 2 and N 2 O. The Mn/Ce/Nb/Ti catalyst displayed 100% NO conversion from 150 to 250 °C and >90% N 2 selectivity below 250 °C. The specific surface area of the catalyst was increased and its surface acidity was strengthened after Nb doping. Moreover, Nb doping increased the NO oxidation ability and lowered the NH 3 oxidation activity of the catalyst. All the above factors contributed to enhancing the overall NH 3 -SCR performance of the Mn/Ce/Nb/Ti catalyst compared with that of the Mn/Ce/Ti one. The long-term stability and resistance to H 2 O and SO 2 of the Mn/Ce/Nb/Ti catalyst were also evaluated.
研究领域:
环境科学
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催化化学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2024
·
IF 20.2
Hongchun Sun,Cui Dong,Chao Feng,Hui Wang,Zhenping Qu
Co 3 O 4 catalysts possess high activity in selective catalytic oxidation of NH 3 (NH 3 -SCO), but the low N 2 selectivity hinders their potential application. To enhance N 2 selectivity, the chemical bonded Nb-O-Co catalyst by the deposition of Nb species onto Co 3 O 4 (Nb/Co 3 O 4 -0.03) is constructed. It shows 100 % NH 3 conversion and 82 % N 2 selectivity at 180°C, and the N 2 selectivity is 2.2-fold higher than that of Co 3 O 4 (38 %). The failure of enhancement in N 2 selectivity for physically mixed Co 3 O 4 and NbO x (NbO x |Co 3 O 4 -0.03) further indicates the crucial role of chemical bonded Nb-O-Co in enhancing N 2 selectivity. In situ diffuse reflectance infrared Fourier transform spectra and NH 3 temperature-programmed desorption results show the formation of new NH 3 adsorption sites. Importantly, intermediates NO - stabled on Nb/Co 3 O 4 -0.03 tends to react with -NH 2 to produce N 2 through internal selective catalytic reduction (iSCR). This work offers insights into enhancing the N 2 selectivity in NH 3 -SCO and advances understanding of iSCR mechanism.
研究领域:
化学工程
·
环境科学
✓ 已验证
DOI
高影响因子
JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2025
·
IF 9.7
Minghu Zhao,Junyi Chen,Fei Wu,Yungang Wang,Kai Chen,Chao Xiong,Rongshu Zhu
Rationally designing catalysts suitable for flue gas purification at low temperatures and unraveling the anti-poisoning mechanism at the atomic level remain challenges. Here, a highly dispersed Ni-doped MnO x catalyst (Ni 0.1 Mn 0.9 O x ) was constructed and applied for selective catalytic reduction (SCR) of nitrogen oxides (NO x ). The long-term stability of Ni 0.1 Mn 0.9 O x is up to 80% (180 ℃) after 18 h under SO 2 and H 2 O conditions. This is due to the fact that the highly dispersed Ni atoms enhance the redox and surface acidity of MnO x , and modulate the electronic structure of the active Mn sites. The denitrification reaction on Ni 0.1 Mn 0.9 O x mainly follows the Eley-Rideal mechanism. The anti-poisoning mechanism is that the introduction of Ni weakens the electron transfer between the Mn site and SO 2 , thereby inhibiting the adsorption of SO 2 . In particular, the H 2 O adsorbed on the Ni sites is decomposed to replenish the depleted Brønsted acid sites, which facilitates the adsorption of NH 3 . However, an excess of H 2 O can have an inhibitory effect. In addition, the mesoporous structure may increase the mass transfer rate and reduce the accumulation of harmful substances. This study provides viable insights for the design of SCR catalysts with excellent anti-poisoning ability.
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
ACS Applied Materials & Interfaces
·
2021
·
IF 9.229
Jiayu Feng,Fei Wang,Chi Wang,Kai Li,Xin Sun,Ping Ning
In this study, an NH3 plasma-treated Cu/HZSM-5 sorbent was introduced to simultaneously remove H2S and PH3 in low-temperature and low-oxygen environments. The effects of the Cu loading amounts, modification methods, and plasma-treatment conditions on the adsorption–oxidation performance of the sorbents were investigated. From the performance test results, the sorbent treated by NH3 plasma with the specific energy input (SEI, electrical input energy to the unit volume of gas) value of 1 J·mL–1 (Cu/HZSM-5-[S1]) was identified as having the highest breakthrough capacities of 108.9 mg S·g–1 and 150.9 mg P·g–1 among all of the materials tested. After three times of regeneration, the sorbent can still maintain the ideal performance. The results of Fourier transform infrared (FT-IR) spectroscopy and CO2 temperature-programmed desorption (CO2-TPD) indicated that the NH3 plasma treatment can introduce amino groups (functional groups) onto the sorbent surface, which greatly increases the number and strength of the basic sites on the sorbent surface. Results of N2 adsorption/desorption isotherms and scanning electron microscopy–energy dispersive spectroscopy (SEM–EDS) showed that the morphology of the sorbent changed after the plasma treatment, which exposed more active sites (copper species). In situ IR spectra showed that the amino groups are continuously consumed during the reaction process, indicating that these amino groups can help sorbents to capture gas molecules. Moreover, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses indicated that CuO is the main active species and the consumption of CuO and accumulation of the reaction products on the surface and inner pores of the sorbent are the primary reasons for the deactivation of the sorbent.
研究领域:
环境科学
·
材料科学
✓ 已验证
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2022
·
IF 9.136
Huixian Zhou,Hui Zhong,Yiqing Zeng,Yutang Kang,Bin Chen,Shuanglu Ma,Yifan Li,Yu Zhang,Shasha Feng,Zhaoxiang Zhong,Weihong Xing
The strategy of constructing catalytic membrane has a significant influence on its structure and performance. In this work, Co 3 O 4 -C x @SiO 2 nanofiber membranes (NFMs) were fabricated by an in-situ growth–pyrolysis–oxidation strategy. The Co 3 O 4 -C x catalyst derived from ZIF-67 was wrapped around nanofibers, which helps to maintain a stable membrane structure, then suppressing the reduction of gas permeability. Among the Co 3 O 4 -C x catalyst, the carbon skeleton can prevent the agglomeration of Co 3 O 4 nanoparticles, obtaining an ultra-fine Co 3 O 4 nanoparticles with high dispersibility, redox property and surface area. The obtained Co 3 O 4 -C 300 @SiO 2 NFM exhibits outstanding ammonia selective catalytic reduction (NH 3 -SCR) denitrification activity (T 90 = 225 °C at a GHSV of 77,000 h −1 ). The effect of catalyst loading on PM 2.5 filtration performance of SiO 2 NFM was also tested. Co 3 O 4 -C 300 @SiO 2 NFM has higher filtration efficiency (99.99%) than SiO 2 NFM at a lower pressure drop of 58 Pa, which suggests that catalyst loading via our method can improve the filtration performance of SiO 2 NFM. This work might provide a universal strategy for the design and preparation of highly efficient catalytic membrane.
研究领域:
环境科学
·
材料科学
✓ 已验证
DOI
高影响因子
Environmental Progress & Sustainable Energy
·
2013
·Vol. 33
·期 2
·385-389
·
IF 0.865
Wei-guo Pan,Yue Zhou,Rui-tang Guo,Wen-long Zhen,Jie-nan Hong,Hong-jian Xu,Qiang Jin,Cheng-gang Ding,Shi-yi Guo
CeO-CuO catalysts were prepared by citric acid method at different calcination temperatures. The purpose of this study is to investigate the influence of calcination temperature on the catalytic activity of CeO 2 -CuO catalyst for the selective catalytic reduction of NO with NH 3 . As can be seen from the results, Ce-Cu(450) is of the best low temperature selective catalytic reduction (SCR) activity among the three catalysts, which may be resulted from its large surface area, good redox ability, strong NH 3 adsorption capacity, and high concentration of Cu 2+ and active oxygen species on the surface. © 2013 American Institute of Chemical Engineers Environ Prog, 33: 385–389, 2014
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
CHINESE JOURNAL OF CHEMICAL ENGINEERING
·
2021
·
IF 3.171
Xin Yong,Hong Chen,Huawang Zhao,Miao Wei,Yingnan Zhao,Yongdan Li
The effects of SO 2 on an one-pot synthesized Cu-SSZ-13 catalyst for selective reduction of NO x by NH 3 were examined. The addition of SO 2 inhibited NO x conversion significantly below 300 °C, while no effect on NO x conversion was observed above 300 °C. TGA, TPD , and XPS results showed that the deactivation was caused by the formation of (NH 4 ) 2 SO 4 , SO 2 chemisorption on the isolated Cu 2+ ion sites, as well as the formation of CuSO 4 -like species. Among them, the site-blocking effect of (NH 4 ) 2 SO 4 on Cu 2+ was the primary reason for deactivation. Fortunately, 89% of deNO x activity of the poisoned catalyst was recovered after thermal treatment at 500 °C in air, where (NH 4 ) 2 SO 4 was completely decomposed. The activity was further recovered with regeneration temperature increasing to 600 °C, removing the adsorbed SO 2 on the Cu 2+ sites. The regeneration at 600 °C could not recover the activity completely, because of the high stability of CuSO 4 -like species.
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
危险品化学品经营许可证（带存储）