SEPARATION AND PURIFICATION TECHNOLOGY
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2020
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IF 5.774
Pengfei Li,Dawei Shang,Wenhui Tu,Shaojuan Zeng,Yi Nie,Lu Bai,Haifeng Dong,Xiangping Zhang
Ammonia (NH 3 ) is one of the main reasons for the formation of aerosols. NH 3 pollution mainly comes from a large amount of emissions in industrial production. Ionic liquids (ILs), as a green solvent, can efficiently separate and recover NH 3 from industrial NH 3 -containing tail gas. In this work, novel protic ionic liquids (PILs) with hydrogen bond donating ability were designed and synthesized by incorporating six-membered N -heterocyclic compounds including pyridinium and piperidinium as cations. Three pyridinium-based PILs with single protic H showed higher NH 3 capacity with the maximum of 3.078 mol NH 3 /mol IL at 313.1 K and 0.10 MPa than the piperidinium-based PILs with double interaction sites. However, there was obvious reduction in NH 3 capacity for pyridinium-based PILs during absorption and absorption-desorption cycles. The reason is that the acidic protic H of cations of pyridinium-based PILs is easily stripped in supersaturated alkaline environment due to the smaller p K a of pyridine derivatives than that of NH 3 , forming the NH 4 + and volatile neutral pyridine derivatives. This work will provide useful guidance to the design of novel ILs used for efficient and reversible absorption of NH 3 .
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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
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2019
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IF 3.375
Siqian Zhang,Cheng Zhang,Qiang Wang,Wha-Seung Ahn
A series of ZSM-5 catalysts were synthesized using fly ash from power plants and red mud from aluminum production in different weight ratios. The ZSM-5 was subsequently coimpregnated with Co and Mn and tested for the low-temperature selective catalytic reduction of NOx by NH3 (NH3-SCR). These catalysts were characterized by XRD, N2-adsorption isotherms, SEM, XPS, and H2-TPR. Among all the prepared catalysts, 5 wt % Co 10 wt % Mn/ZSM-5 had shown the best catalytic activity, with 98.8% conversion of NOx and 90.7% selectivity toward N2 at 150 °C. This is comparable to the performance of a similar ZSM-5 catalyst prepared using chemical reagents. The high ratio of Mn4+/(Mn4+ + Mn3+ + Mn2+) in the catalyst improved the NOx conversion, whereas the moderate redox property imparted by Co3+ led to high N2 selectivity. This catalyst also showed strong resistance against poisoning in 100 ppm SO2 and 5% H2O. This work demonstrates that effective NOx removal treatment with high N2 selectivity and sufficient stability for either cement plants or incinerators can be achieved by using a porous catalyst/support material produced from industrial solid wastes.
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Advances in Materials Science and Engineering
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2019
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IF 1.399
Zhuo Yao,Dianli Qu,Yuxiang Guo,Yujing Yang,Hong Huang
Novel catalysts with high activity for the selective catalytic reduction of NO with NH3 (NH3-SCR) at low temperatures are highly demanded. In this study, mixed-node metal-organic frameworks (MOFs), e.g. Mn@CuBTC with controlled Mn composition in Cu3(BTC)2, were fabricated using postsynthetic exchange method and their structural characteristics and catalytic performances for NH3-SCR reaction were assessed. A series of analyses in terms of structure, surface morphology, texture, and chemical state determined that Mn ions were successfully incorporated into the Cu3(BTC)2 crystal lattice as well as adsorbed on the walls of nanopores in the framework. The pore sizes can be finely tuned in the presence of Mn ions in the cages, which significantly suppressed water adsorption. The NH3-SCR activity of Mn@CuBTC exhibited nearly 100% NOx conversion rate in the temperature range (230–260°C). The superior NH3-SCR performance is attributed to the proper pore sizes, reduced water content, and the synergistic effect between manganese and copper ions in the MOF structure, which enhanced NH3 bound to the active Lewis sites.
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AICHE JOURNAL
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2019
·Vol. 65
·期 10
·e16684
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IF 3.463
Lei Song,Kui Ma,Wen Tian,Junyi Ji,Changjun Liu,Siyang Tang,Wei Jiang,Hairong Yue,Bin Liang
A novel FeTiSO x catalyst prepared by a simple hydrolysis coprecipitation method was used for the selective catalytic reduction (SCR) of NO x with NH 3 , which exhibited high catalytic activity (NO x conversion of >97% and N 2 selectivity of >95%) and tolerance for both H 2 O and SO 2 at a broad temperature window of ~325–475°C. The characterization results showed that the formation of Fe–O–Ti and Fe–O–S species could significantly enhance the acidic sites of the catalyst, which play an important role in NH 3 absorption and their catalytic activity. The Fe 3+ ions in the bulk anatase TiO 2 could significantly enhance the redox properties for the SCR reaction and suppress the side reaction of NH 3 oxidation to NO or N 2 O. In addition, the reaction mechanism was discussed based on in situ diffuse reflectance infrared Fourier transform spectroscopy measurements and kinetic investigation, indicating that the reaction was dominated by the Eley–Rideal mechanism over the FeTiSO x catalyst.
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Journal of Physical Chemistry C
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2018
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IF 4.484
Zhiqiang Xie,Congbiao Chen,Bo Hou,Dekui Sun,Heqin Guo,Jungang Wang,Debao Li,Litao Jia
The nature of high-silica H–Y acid sites in dimethoxymethane carbonylation is investigated by NH3 poisoning with a combination of reaction results, diffuse reflection infrared Fourier transform spectra, and NH3 temperature-programmed desorption. After NH3 poisoning of H–Y, ammonia desorption of zeolites NH4–Y was conducted at different temperatures to obtain catalysts HNH4–Y that gradually exposed different acid sites. The zeolites thus produced catalyzed dimethoxymethane carbonylation with a linear dependence of the conversion on the ammonia desorption temperature before the plateau stage. It was observed that strong Brønsted acids in zeolite Y catalyzed the reaction more selectively toward the main product methyl methoxyacetate, and weak Brønsted acids catalyzed the reaction more selectively toward the byproduct methyl formate. Furthermore, the turnover frequency of Brønsted acids varied significantly among the Brønsted acids and decreased with acid strength. This finding suggested that only 10.1–18.3% of the total Al in zeolite Y with Si/Al ratios of 15, 30, and 40 contributed to the total framework Brønsted acids.
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ELECTROCHIMICA ACTA
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2018
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IF 5.116
Bo Xu,Zaichun Liu,Weibin Qiu,Qian Liu,Xuping Sun,Guanwei Cui,Yuping Wu,Xiaoli Xiong
Identification of new effective and selective N 2 reduction electrocatalyst is still of critical importance for fundamental and application research. Here, we report La 2 O 3 nanoplate performing as an efficient metal oxide catalyst for electrochemical N 2 fixation to NH 3 , which exhibits excellent selectivity and stability with a high Faradaic efficiency of 4.76% and a NH 3 yield rate of 17.04 μg h −1 mg −1 cat. at −0.8 V vs. reversible hydrogen electrode (RHE) in 0.1 M Na 2 SO 4 solution under atmospheric pressure. Density functional theory (DFT) calculation results show that La atoms in La 2 O 3 act as the active sites for efficiently adsorbing N 2 . The optimal adsorption approach of N 2 molecule on the (011) face of La 2 O 3 is end-on-two configuration which is highly activated. Thus La 2 O 3 exhibits high performance for electrochemical reduction of N 2 .
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CHINESE JOURNAL OF CATALYSIS
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2018
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IF 3.525
Lei Chen,Ding Weng,Jiadao Wang,Duan Weng,Li Cao
The CeO 2 -TiO 2 (CeTi) and CeO 2 /WO 3 -TiO 2 (CeWTi) catalysts were prepared by a sol-gel precipitation method and their NH 3 -NO/NO 2 selective catalytic reduction (SCR) performance was studied. N 2 O formation and effect of oxygen concentration on SCR performance over CeWTi catalyst were also investigated while varying the NO 2 /NO x ratio. Results indicate that fast SCR behavior of CeWTi catalyst has the best NH 3 -NO/NO 2 SCR performance due to the catalyst reoxidation rate by NO 2 higher than by O 2 . Compared with CeTi catalyst, CeWTi catalyst exhibits higher de-NO x performance under NH 3 -NO/NO 2 SCR conditions. As the CeTi and CeWTi catalysts exhibit similar redox property, addition of WO 3 provides more acid sites which accelerate the reaction between NH 4 NO 3 and NO to get a superior low-temperature activity. Amount of N 2 O formation shows a peak at 250 °C mainly derived from NH 4 NO 3 decomposition.
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Environmental Progress & Sustainable Energy
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2013
·Vol. 33
·期 2
·385-389
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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
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FUEL PROCESSING TECHNOLOGY
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2016
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IF 3.847
Wei Li,Rui-tang Guo,Shu-xian Wang,Wei-guo Pan,Qi-lin Chen,Ming-yuan Li,Peng Sun,Shu-ming Liu
Heavy metals (such as Zn and Pb) have a deactivation effect on the catalyst for selective catalytic reduction of NO with NH 3 . In this study, it was found that the modification of Mn/TiO 2 catalyst by Nb could greatly enhance its Zn resistance. From the characterization results of BET, XRD, H 2 -TPR, NH 3 -TPD, it may be concluded that the introduction of Nb into Mn/TiO 2 catalyst would lead to its lower crystallinity , more acid sites and higher concentrations of Mn 4 + and surface chemisorbed oxygen. The results of in situ DRIFT study reveal that the NH 3 -SCR reactions over Mn/TiO 2 and Mn-Nb/TiO 2 all obey both the Langmuir-Hinshelwood mechanism and the Eley–Rideal mechanism, and the doping of Nb on Mn/TiO 2 catalyst could promote the adsorption of NH 3 and NOx species on it. All these features make a contribution to the high SCR activity and good Zn resistance of Mn-Nb/TiO 2 catalyst.
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RSC Advances
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2017
·Vol. 7
·期 53
·33510-33520
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IF 3.108
Jinwei Wei,Bo Liang,Qingpeng Cao,Chentian Mo,Youming Zheng,Xuesong Ye
In this paper, vertically aligned PANI nanorod arrays were successfully prepared on GO nanosheets at low temperature via a dilute polymerization method, in which the GO nanosheets with abundant hydrophilic groups were employed to support the heterogeneous growth of uniformly-distributed PANI nanorod arrays. The acquired nanocomposite was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). NH3 sensing performances of the as-prepared nanocomposite were carefully examined. With the help of the enhanced synergistic effect derived from the large number of p–n heterojunctions in the deliberately-designed microstructure, the device exhibited an enhanced response to NH3 vapor (14.63 at 50 ppm), wide dynamic range (1–6400 ppm), and fast response and recovery processes, in comparison to pure PANI nanofibers. The impact of the drop-coating amount of the sensing nanocomposite on the sensing performances was also investigated to find out the suitable amount for fabricating a high-performance ammonia sensor. Herein, the superior performances of the proposed well-organized microstructure make it an effective nanocomposite for gas sensing applications.
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COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
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2024
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IF 4.9
Tian Gu,Chengzhi Wang,Denghui Chen,Mengmeng Han
Modulating the physicochemical properties of catalysts through the construction of special crystal structures or microscopic morphology provides new insights for developing high-performance low-temperature denitrification catalysts. This paper explores the effect of morphology structure on catalyst performance and identifies the dominant driving factors. The catalyst activity sequence was found to be MnO x spiny nanospheres (Mn-SNS) > MnO x nanowires (Mn-N) > MnO x nanospheres (Mn-NS) > MnO x nanoparticles (Mn-P). Among these, the Mn-SNS catalyst prepared by the hydrothermal method exhibited the best catalytic activity and the good resistance to water and sulfur. It achieved over 70% NO x conversion at 150 °C, and maintained 100% at 200–350 °C. In the presence of SO 2 and H 2 O, the NO x conversion was maintained at 87%. The spherical structure consisting of nanospikes provides the Mn-SNS catalysts with a large specific surface area, more (Mn 4+ +Mn 3+ ), abundant acid sites, and stronger reducibility, thus exhibiting excellent performance through the "fast-SCR" pathway. It also inhibits oxide crystallization and provides more sites for the adsorption activation of NO x and NH 3 . The nanowire structures can provide a large specific surface area and a high concentration of Mn 3+ and Mn 4+ for MnO x catalyst. Characterization analyses revealed that the specific surface area, the ratio of (Mn 4+ +Mn 3+ )/Mn, and the number of Lewis acid sites (L-NH 3 ) are the most important factors affecting the catalytic activity. This present empirical analysis provides new ideas for designing high-performance catalysts with a large specific surface area.
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SENSORS AND ACTUATORS B-CHEMICAL
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2025
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IF 7.7
Yan Wang,Chong Li,Xuejin Li,Jinghan Zhang,Xinghong Chen,Xueming Hong,Jingting Luo,Zhenglong Sun,Fujian Ren,Ran Tao,Yuzhi Chen
The detection of toxic ammonia (NH 3 ) gas across multiple channels at room temperature, especially under complex conditions, consistently presents a significant challenge. In this paper, a plasmonic Pt-doped SnO 2 enhanced quantum wires NH 3 gas sensor is constructed on a 125-µm communication fiber with easy networking. To enhance usability in confined areas, the sensor features a compact plug-in fiber probe design. The plasmonic Pt-doped SnO 2 enhanced quantum wires coating boosts the interaction between NH 3 gas molecules and oxygen adsorbed on the wires' surface, modulating the plasmonic optic signal. We present and compare two optical modulation methods-wavelength and intensity-for our NH 3 gas probe. Our sensor achieves an impressive intensity sensitivity of -10.45 a.u./ppm at room temperature with a rapid response time of 3.8 s. Furthermore, intensity modulation offers an exceptionally low detection limit of 287 ppb, with minimal susceptibility to temperature and humidity variations. The proposed fiber NH 3 gas probe exhibits commendable specificity, repeatability, stability, and cost-effectiveness, along with flexibility in light source and receiver choices, making it ideal for NH 3 gas detection applications.
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