APPLIED SURFACE SCIENCE
·
2018
·
IF 4.439
Weiyuan Yao,Xiaoqiang Wang,Yue Liu,Zhongbiao Wu
In this paper, Ce O P material (mainly consisted of CePO 4 ) and TiO 2 supported CeO 2 catalysts were prepared by wet impregnation route for the selective catalytic reduction (SCR) of NO with NH 3 . The SCR activity results had revealed that CeO 2 /Ce O P-0.4 catalyst yielded over than 90% NO conversion within the temperature range of 200–300 °C, whereas the deNO x efficiency of CeO 2 /TiO 2 -0.4 catalyst was less than 30% at 200 °C. After a series of characterization tests, it was found that CeO 2 /Ce O P catalysts were of better dispersion of active phase than CeO 2 /TiO 2 owing to the strong interactions between CeO 2 and surficial Ce O species on Ce O P material. Thus, more active oxygen species could participate in the SCR reaction at low temperature. Furthermore, compared to CeO 2 /TiO 2 sample, the surface acidity was greatly enhanced for CeO 2 /Ce O P catalysts by the introduction of the acidic support, benefiting the adsorption of NH 3 . Both of which were attributed to the main reasons of the promoted SCR performance over CeO 2 /Ce O P catalysts. Moreover, the NO x ad-species on CeO 2 /TiO 2 sample were very stable and could hardly react with adsorbed NH 3 , impeding L-H reaction pathway at low temperature.
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JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY
·
2013
·
IF 2.145
Rui-tang Guo,Yue Zhou,Wei-guo Pan,Jie-nan Hong,Wen-long Zhen,Qiang Jin,Cheng-gang Ding,Shi-yi Guo
CeO 2 /Al 2 O 3 catalysts prepared by three methods were investigated for selective reduction of NO with NH 3 . It was found that the catalyst prepared by the single step sol–gel method had the best SCR activity and SO 2 resistance performance. From the results of BET, XRD, TPD and TPR, it can be concluded that large surface area, strong interaction, highly dispersed nano-crystalline ceria , high NH 3 adsorption capacity and good redox ability might be the main reasons for the excellent performance of CeO 2 /Al 2 O 3 catalyst prepared by the single step sol–gel method.
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Catalysis Science & Technology
·
2015
·Vol. 5
·期 4
·2260-2269
·
IF 5.426
Qiulin Zhang,Xin Liu,Ping Ning,Zhongxian Song,Hao Li,Junjie Gu
Mesoporous Ce–Ti–MoOx catalysts have been prepared by stabilization with an in situ formed carbon template and used for selective catalytic reduction of NOx with NH3 (NH3-SCR). The Ce–Ti–MoOx catalysts were characterized by N2 adsorption–desorption, XRD, HR-TEM, H2-TPR and XPS analysis. It was found that the stabilization with a carbon template obviously improved the NOx conversion of the Ce–Ti–MoOx catalyst and the pore distribution. The Ce–Ti–MoOx catalyst stabilized with a carbon template at 850 °C in N2 exhibited the best NH3-SCR activity and showed a uniform mesopore distribution, and more than 90% NOx conversions were obtained at 175–425 °C with a GHSV of 60 000 h−1. The high stabilization temperature with a carbon template in N2 not only led to an increase in specific surface area, pore volume and low-temperature SCR activity, but also contributed to the enhanced redox properties, highly dispersed titanium or molybdenum species and narrow mesopore distribution. The treatment of Ce–Ti–MoOx with a high calcination temperature for removal of the carbon template led to a drastic decrease in surface area, an abrupt decrease in surface oxygen and cerium, production of rutile TiO2, and a correspondingly low SCR activity.
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Journal of Physical Chemistry C
·
2015
·
IF 4.772
Weiyuan Yao,Yue Liu,Xiaoqiang Wang,Xiaole Weng,Haiqiang Wang,Zhongbiao Wu
In this paper, a sol–gel made Ce–O–P catalyst (referred to as Ce–O–P-SG) was employed for selective catalytic reduction (SCR) of NOx with NH3, which was directly compared with two other Ce–O–P samples as synthesized via hydrothermal and coprecipitation routes (referred to as Ce–O–P-HT and Ce–O–P-CP, respectively). Experimental results revealed that the Ce–O–P-SG catalyst yielded a more than 90% NO conversion at 200 °C in the presence of 10 vol % H2O, whereas Ce–O–P-HT and Ce–O–P-CP catalysts only showed 50% and 20% NO conversions under the same conditions, respectively. After subjected to a series of characterization technologies (e.g., XRD, BET-BJH, XPS, NH3-TPD, py-IR, and H2-TPR), it was found that more enriched surface Ce(4+) species were formed except for the two main CePO4 phases (monazite and rhabdophane phases) of the Ce–O–P-SG catalyst compared to the other two samples, resulting in the increase of surficial active oxygen ions content. This could lead to an enhancement in surface acidity and redox capacity of the Ce–O–P-SG catalyst, effectively promoting the NH3–SCR activity of the catalyst. Further analyses on SO2 and H2O tolerance revealed that the Ce–O–P-SG possessed a higher sulfur resistance than the other two samples, which could be attributed to the SO2 trapping effect by the abundant active oxygen species over Ce–O–P-SG catalyst.
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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2016
·
IF 2.567
Peijian Wang,Jisong Zhang,Kai Wang,Guangsheng Luo,Pei Xie
NH3 was used as acid absorbent to intensify the reactions between aniline and benzoyl chloride in a microstructured chemical system in this work. By suppressing the side reaction, the addition of NH3 could reduce the reaction time needed for 99% reactants conversation to less than 1/10 of the condition without NH3. Furthermore, a complete kinetic model containing two rapid main reactions and two reversible consecutive side reactions was established, and six reaction rate constants and their corresponding activation energies and pre-exponential factors as well as confidence intervals were determined precisely. The accuracy of the obtained parameters was verified by comparing the calculated data with experimental data at extensional temperature. The kinetic model was used to optimize the intensification operating conditions, and effects of reactants concentration, temperature, NH3 addition amount, and NH3 feed methods were discussed based on the simulation results. This work proves that the microstructured chemical system not only provides an effective intensification ability but also develops a reliable platform for kinetic studies.
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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.
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Applied Sciences-Basel
·
2018
·Vol. 8
·期 1
·95
·
IF 1.689
Chengzhi Wang,Cheng Zhang,Yonggang Zhao,Xin Yan,Peng Cao
Honeycomb cordierite-based Mn–Ce/Al2O3catalysts were prepared by the impregnation method and used for low-temperature selective catalytic reduction (SCR) of NOxwith NH3, with and without SO2and/or H2O in a homemade fixed-bed tubular reactor. The catalyst reached nearly 80% NOxconversion at 100 °C in the absence of SO2. However, SO2reduces the catalytic activity (80% to 72%) of the honeycomb cordierite-based Mn–Ce/Al2O3catalysts under identical conditions. This finding demonstrated that the catalyst exhibited high activity at low temperature and excellent SO2resistance in the presence of 50 ppm SO2. The fresh and sulfated honeycomb cordierite-based Mn–Ce/Al2O3catalysts were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), N2adsorption–desorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetry and differential thermal analysis (TG-DTA), and Fourier transform infrared (FT-IR) spectroscopy. Characterization results indicated that the deactivation by SO2was primarily the result of the deposition of ammonium hydrogen sulfate and sulfated CeO2on the catalyst surface during the SCR process. The formed sulfates depressed the catalytic activity via the blocking of pores and the occupation of active sites. Additionally, the competitive adsorption between SO2and NH3always decreased the catalytic activity.Keywords:Mn–Ce/Al2O3catalyst;low temperature selective catalytic reduction;honeycomb cordierite;SO2resistance
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RSC Advances
·
2018
·Vol. 8
·期 7
·3858-3868
·
IF 2.936
Shuohan Yu,Sheng Xu,Bowen Sun,Yiyang Lu,Lulu Li,Weixin Zou,Peng Wang,Fei Gao,Changjin Tang,Lin Dong
Chromium oxide nano-particles with an average diameter of 3 nm covered by amorphous carbon (CrOx/C) were successfully synthesized. The synthesized CrOx/C materials were used for the selective catalytic reduction of NOx by NH3 (NH3-SCR), which shows superb NH3-SCR activity and in particular, satisfactory regeneration ability in the presence of SO2 compared with Mn-based catalysts. The as-prepared catalysts were characterized by XRD, HRTEM, Raman, FTIR, BET, TPD, TPR, XPS and in situ FTIR techniques. The results indicated presence of certain amounts of unstable lattice oxygen exposed on the surface of CrOx nano-particles with an average size of 3 nm in the CrOx/C samples, which led to NO being conveniently oxidized to NO2. The formed NO2 participated in NH3-SCR activity, reacting with catalysts via a “fast NH3-SCR” pathway, which enhanced th NH3-SCR performance of the CrOx/C catalysts. Furthermore, the stable lattice of the CrOx species made the catalyst immune to the sulfation process, which was inferred to be the cause of its superior regeneration ability in the presence of SO2. This study provides a simple way to synthesize stable CrOx nano-particles with active oxygen, and sheds light on designing NH3-SCR catalysts with highly efficient low temperature activity, SO2 tolerance, and regeneration ability.
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PubMed
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2025
·
IF 9
Yuan Cheng,Sheng Zhou,Kunfeng Zhao,Fawen Wu,Dechun Huang,Hongliang Qian
Although deep eutectic solvents (DESs) are green ammonia capture solvents with simple synthesis and easy availability of raw materials, their absorption rate is limited due to inherent high viscosity barrier. Herein, a high-viscosity hybrid DES (choline chloride/resorcinol/glycerol = 1:3:5, CRG) was encapsulated in a highly permeable shell of polydimethylsiloxane (PDMS) by microfluidics. The absorption capacity and absorption rate of the 550 μm Microcapsule were found to be 1.45 and 6.01 times higher than that of unpacked CRG respectively for the increased mass transfer area of CRG. Additionally, the 550 μm Microcapsule maintained 93 % of its initial maximum absorption capacity after 8 cycles. Moreover, a model of mass transfer resistance 1 / k μ based on chemical potential into the ammonia absorption rate formula was established. Then 1 / k μ related to the sizes of microcapsules was proposed based on the observation that there is a certain linear relationship between d m NH 3 / d t and l n ( x NH 3 , e / x NH 3 , t ) , based on which, mass transfer enhancement mechanism was analyzed. This study is the first to extend the concept of microencapsulation to the field of ammonia capture, which has a certain guiding role for other gases capture research.
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Environmental Technology & Innovation
·
2025
·
IF 7.1
Hua Huang,Xiaoyan Liu,Xianying Shan,Jingrong Yang,Lijuan Ding,Rongyu Zhang,Jiale Dai,Yanzhong Zhen,Jian Wang,Di Guo,Yu Liu,Wenfeng Jiang,Zhirui Niu
Since hydrothermal aqueous phase (HAP) contains abundant nutrients and humic-like substances, it is developed as nitrogen (N) fertilizer to improve plant growth and soil quality. However, significant NH 3 volatilization is a major drawback in dryland soil. To solve this problem, a compound fertilizer of HAP and urea was modified with various dosage (0.25 % - 5.0 %) of urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT). The NH 3 , N loss, and lettuce growth were evaluated in parallel soil column and pot experiments. Results showed that increasing NBPT dosage increased soil dissolved organic N (DON) and ON while decreased NH 4 -N, NH 3 , N loss, urease activity, and ureC . NBPT successfully inhibited ammonification. Increasing NBPT dosage increased NO 3 -N but decreased PAO and AOA . The utilization rate of metabolic substrate (NH 4 -N) was more important for forming NO 3 -N, as evidenced by the negative correlation of NO 3 -N and NH 3 . The DON from HAP included N-heterocyclic compounds, which are toxic for nitrifiers. The toxic DON also significantly decreased root dry weight by 22.31 % when 5.0 % NBPT was added. The optimal additive dosages were 0.5 % and 2.0 % in the column and pot experiments, respectively, which decreased NH 3 and N loss by 45.38 % and 32.08 %. Further increasing NBPT dosage no longer decreased N loss but did harm to plant root. Therefore, this study demonstrated that an appropriate addition of NBPT to HAP fertilizer can effectively reduce ammonia volatilization and N loss. The innovative technique would promote the utilization of HAP resource within the context of sustainable dryland agriculture.
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Frontiers of Chemical Science and Engineering
·
2017
·Vol. 11
·期 4
·594-602
·
IF 1.712
Zhang Minhua,Huang Baojuan,Jiang Haoxi,Chen Yifei
A mild in-situ deposition method was used to fabricate Mn-based catalysts on a UiO-66 carrier for the selective catalytic reduction of NO by NH 3 (NH 3 -SCR). The catalyst with 8.5 wt-% MnO
x
loading had the highest catalytic activity for NH 3 -SCR with a wide temperature window (100–290 °C) for 90% NO conversion. Characterization of the prepared MnO
x
/UiO-66 catalysts showed that the catalysts had the crystal structure and porosity of the UiO-66 carrier and that the manganese particles were well-distributed on the surface of the catalyst. X-ray photoelectron spectroscopy analysis showed that there are strong interactions between the MnO
x
and the Zr oxide secondary building units of the UiO-66 which has a positive effect on the catalytic activity. The 8.5 wt-% MnO
x
catalyst maintained excellent activity during a 24-h stability test and exhibited good resistance to SO 2 poisoning.
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2024
·
IF 8.1
Bo Zhao,Mingze Han,Qiushi Wang,Zikun Huang,Yunhong Liang,Kaniki Tumba,Mo Li,Weiwei Chen,Masroor Kamal,Zhiyong Chang,Jiangtao Qi,Li Guo
Particulate matter (PM), ammonia (NH 3 ) and other polluted gases emitted from animal feeding operations have emerged as significant risks to workers, surrounding residents, and the regional environment. Therefore, the development of air filters capable of simultaneously filtering PM and adsorbing toxic gases is particularly important. In this study, a three-layer gradient structure nanofiber filter was prepared by electrospinning technology, consisting of fluorinated Polylactic acid (PLA)/SiO 2 as the outer layer, PLA nanofibers as the middle layer, and PLA/UiO-66-NH 2 as the inner layer. This gradient structure of composite filter featured gradually decreasing pore sizes, exhibited optimal air filtration performance compared to PLA filter and commercial glass fiber filter. At 5.3 cm/s flow rate, the composite nanofiber filter achieved high filtration efficiency (99.15 % for PM 0.5 ) and low pressure drop (89.65 Pa). Furthermore, the composite nanofiber filter exhibited highest dust holding capacity, indicating longer service life. It also featured excellent self-cleaning capabilities, allowing for reuse after simple water rinsing. Additionally, the results of ammonia (NH 3 ) adsorption tests demonstrated the prepared composite filter’s highest adsorption capacity for NH 3 . Therefore, this work enhanced the application potential of high-performance air filters in the removal of PM pollution and hazardous gases.
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