Fire-Switzerland
·
2023
·Vol. 6
·期 12
·456
·
IF 3.2
Jin Wang,Zhichao Zheng,Bin Liu,Ziwei Wang,Shuang Wang
An efficient catalyst is key to achieving the synthesis of electrochemical ammonia and improving safety. In this work, using biomass walnut shell as a carbon source and sodium thiosulfate as a sulfur source, sulfur-modified walnut shell-derived carbon material was synthesized via a simple low-temperature impregnation method at room temperature and atmospheric pressure as an effective electrochemical ammonia synthesis catalyst with high thermal stability. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), nitrogen adsorption–desorption apparatus, thermogravimetry (TG), and other characterization methods were applied to analyze the micro-morphology and physicochemical structure of the electrocatalyst. The synthesized ammonia performance of the catalyst was measured using an ultraviolet (UV) spectrophotometer and electrochemical workstation. The catalyst design used the doping of sulfur atoms to create rich catalytic active sites, while the presence of elemental sulfur on the catalyst surface provided hydrophobicity, which was conducive to inhibiting competitive hydrogen evolution reaction (HER) and enhancing the electrocatalytic ammonia synthesis performance of the catalyst. Under normal temperature and pressure conditions, when a voltage of −0.45 V was applied, the ammonia yield in 0.05 M H2SO4electrolyte was 10.39 μgNH3mgcat.−1h−1. The results showed that the introduction of sulfur effectively improved the electrocatalytic and thermal safety performance of bio-derived carbon materials, and the test presented that the performance of the catalyst was stable and reusable.Keywords:electrocatalysis;non-metallic catalyst;sulfur modification;biomass porous carbon;thermal safety
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高影响因子
FUEL
·
2023
·
IF 7.4
Guoquan Liu,He Zhang,Pengfei Wang,Yi Li,Xueyue Mi,Sihui Zhan
Reducing the poisoning effect of alkaline earth metals over catalysts in industrial fields presents a great challenge to selective catalytic reduction (SCR) of NO x with ammonia. Herein, we successfully introduce sulfates to the surface of supported manganese-based oxides (Nb/MnO 2 -S) for trapping calcium species, and Nb/MnO 2 -S catalyst with superior low-temperature performance and calcium-resistant property still exhibits excellent de-NO x activity in a wide operating temperature window (175–350 °C, over 80 % NO x conversion with a gas hourly space velocity of 60,000 h −1 ) after calcium poisoning. In this case, the addition of sulfates increased the quantity of chemisorbed oxygen on Nb/MnO 2 -S, thus accelerating the redox cycle in NH 3 -SCR reaction. Significantly, compared with calcium-poisoned Nb/MnO 2 , relevant spectroscopy analysis and theoretical calculations further reveal that sulfates species prefer to interact with calcium and release the Nb active sites, which maintains the efficient NH 3 adsorption and preserves a large amount of Brønsted acid sites over calcium-poisoned Nb/MnO 2 -S, thus promoting calcium-resistant performance. This work will provide a general strategy to develop calcium-resistant SCR catalysts with low-temperature activity for industrial applications.
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Catalysis Science & Technology
·
2021
·Vol. 11
·期 15
·5125-5134
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IF 6.119
Yanke Yu,Xianfang Yi,Jiali Zhang,Zhaojian Tong,Changwei Chen,Mudi Ma,Chi He,Jinxiu Wang,Jinsheng Chen,Bingbing Chen
Non-vanadium-based catalysts with high SO2 tolerance are still interesting in selective catalytic reduction of NO by NH3 (NH3-SCR) and SO2 adsorption is the foremost step for the deactivation of catalysts. In order to alleviate the adsorption of SO2, we fabricated a series of rhenium (Re; without stable sulfate) supported TiO2 catalysts and studied their SO2 tolerance for the first time. Owing to suitable surface acidity and reducibility, ReOx/TiO2 catalysts exhibited satisfactory activity in a wide temperature range of 250–350 °C. As expected, experimental results and DFT calculations indicated that SO2 adsorption on ReOx/TiO2 catalysts was rather weak, thus the catalysts performed excellent SO2 tolerance in the NH3-SCR reaction. Moreover, in situ DRIFTS indicated that the NH3-SCR reaction on ReOx/TiO2 catalysts followed the Eley–Rideal mechanism and SO2 had little effect on the reaction mechanism. Our findings should provide new insights into the development of SCR catalysts with high SO2 tolerance.
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高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2020
·
IF 10.652
Xuesong Liu,Peng Jiang,Yong Chen,Yaoguang Wang,Qiaoling Ding,Zhiming Sui,Hongfeng Chen,Zhongyun Shen,Xiaodong Wu
Two Ce-W-Ti mixed oxide catalysts were prepared by wet impregnation (CeW/Ti-I) and mechanical mixing (Ce/W/Ti-M) methods. CeW/Ti-I catalyst exhibits over 80% NO x conversion and nearly 100% N 2 selectivity at 200–550 °C. The superior catalytic performance is associated with the high dispersion of active CeO 2 and acidic WO 3 on TiO 2 and the synergistic effects among different components. The X-ray Diffraction, Raman spectroscopy, Nitrogen physisorption, X-ray photoelectron spectroscopy, H 2 temperature-programmed reduction, temperature-programmed desorption of ammonia and infrared spectroscopy were performed. It is found that the formation of solid solutions, as well as the high specific surface area, would increase the amounts of Ce 3+ , oxygen vacancies and acid sites in the catalyst. These broaden the operating temperature window of NH 3 -SCR reaction and enhance the N 2 selectivity by facilitating “fast SCR” reaction at low temperatures and inhibiting the unselective oxidation of NH 3 at high temperatures.
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高影响因子
ACS Sustainable Chemistry & Engineering
·
2020
·
IF 7.632
Yahui Meng,Huize Luo,Cuihua Dong,Chunliang Zhang,Zhibin He,Zhu Long,Ruitao Cha
Simple, fast, and accurate detection of food freshness is of considerable significance to ensure food safety. The pH values of foods can be good indicators of their freshness, which can be used for real-time detection of food quality. Herein, we fabricated a pH-sensing film for flexible smart labels based on hydroxypropyl guar (HPG), cellulose nanocrystal (CNC), 1-butyl-3-methylimidazolium chloride (BmimCl), a kind of ionic liquid (IL), and anthocyanin (Anth). We investigated the structure, optical properties, and mechanical strength of the composite films. These films can be used to detect ammonia (NH3) generated from seafood during storage by pH-sensing capability and monitor the real-time freshness of seafood. The HPG/CNC/IL/Anth film exhibited several advantages, such as wide color-change range, easy identification, high sensitivity, good reversibility, excellent stability, and low detection limit. The pH-sensing films can function as flexible smart labels for real-time, visual, and accurate detection of food freshness in cold chain logistics and other fields.
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高影响因子
JOURNAL OF MOLECULAR LIQUIDS
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2020
·
IF 5.065
Dawei Shang,Shaojuan Zeng,Xiangping Zhang,Xiaochun Zhang,Lu Bai,Haifeng Dong
Ammonia (NH 3 ) pollution poses a serious environmental threat. Ionic liquids (ILs) are regarded as potential solvents to treat NH 3 -containing gases because of their unique properties, including tunable structures and high affinity for NH 3 molecules. In order to achieve an efficient and reversible absorption of NH 3 , a series of protic ionic liquids (PILs) with multiple active sites were designed by introducing acidic protons, as well as the Li + ion into ILs, resulting in PILs with two acidic protons on cations ([2-Mim][NTf 2 ] and [Im][NTf 2 ]), as well as dual functionalised PILs with a Lewis acidic Li + -based anion and acidic protons on cations, namely, [2-Mim][Li(NTf 2 ) 2 ] and [Eim][Li(NTf 2 ) 2 ]. The NH 3 absorption capacity of [Im][NTf 2 ] was found to be 3.46 mol NH 3 /mol IL, which is the highest among the NH 3 absorption capacities of all known nonmetallic ILs, and is ascribed to the hydrogen bonding interactions between the NH 3 and PIL molecules. Furthermore, [2-Mim][Li(NTf 2 ) 2 ] exhibited the highest NH 3 absorption capacity, with a value of 7.01 mol NH 3 /mol IL, which is about 30 times higher than that of conventional ILs. The superior NH 3 absorption performance of the dual functionalised PILs is attributed to the combination of hydrogen bonding interactions between the protons and the NH 3 molecules, and the formation of coordination complexes between the Li + -based anion and the NH 3 molecules. Moreover, the ILs studied here exhibited excellent recyclability, indicating a great potential for their use in applications involving efficient and reversible NH 3 absorption from NH 3 -containing industrial gases.
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高影响因子
International Journal of Refrigeration
·
2021
·
IF 3.629
Zhenghao Jin,Shuhong Li,Runfa Zhou,Mengkai Xu,Weixue Jiang,Kai Du
The newly NH 3 – H 2 O – LiBr working fluid can decrease the power wasted in the generator, thus improves the COP of the ammonia absorption refrigeration system. But the applying of NH 3 – H 2 O – LiBr working fluid decreases the ammonia absorption efficiency, so the COP of the system is still unsatisfactory. To further enhance the COP of the NH 3 – H 2 O - LiBr absorption refrigeration system, TiO 2 nanoparticles are added to the NH 3 – H 2 O - LiBr working fluid in this study. And the effects of TiO 2 nanoparticles concentration on the performances of the generator, absorber, evaporator, condenser, and solution heat exchanger are tested in an ARS experimental system. The experimental results indicate that the addition of TiO 2 nanoparticles increases the P g , P e , P a , and P c , meaning that the value of ammonia produced in the generator increases. Therefore, the COP and iCOP of the system are improved by adding TiO 2 nanoparticles, and the COP is maximum improved by 18.96% compared with the ammonia-water absorption refrigeration system. When the x TiO2 is increased from 0.3% to 0.5%, the increase rate of the COP decreases because the newly added nanoparticles do not disperse well. So 0.3% is a better choice for the TiO 2 nanoparticles concentration when comprehensively considering the dispersion stability of nanoparticles and the COP.
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高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2021
·
IF 13.273
Li Luo,Jiaran Li,Xiaoyan Chen,Xuegong Cao,Yibang Liu,Zhixin Wu,Xiaoyan Luo,Congmin Wang
In this work, porous PIL-TAs were reported for superhigh capacity and reversible NH 3 uptake, where PIL-TAs are cobaltous thiocyanate (Co(II)(SCN) 4 2- , TA) functionalized poly ionic liquids (PILs). Due to the structural support of TA as well as the interactions between TA and imidazolium cation, the PIL-TAs possess porous structure and optimized properties. Superhigh NH 3 uptake capacity of 13.2–20.1 mmol g −1 at STP of PIL-TAs was achieved, which is higher than most of the reported sorbents. In detail, the cooperative interactions including the NH 3 coordinating with Co(II) instead of SCN - and hydrogen bonding of C2H in imidazolium (C2H…NH 3 ) benefit to high capacity of NH 3 uptake. Reversely, the NH 3 release would be directed by the competition of the free SCN - with NH 3 to reform PIL-TAs. The competitive interaction with SCN - promotes NH 3 release by temperature and pressure swinging, which contributes the adsorbents recyclable. The cooperative and competitive interactions make these PIL-TAs possess high gas capacity and feasible desorption, which might be a potential strategy for designing novel gas sorbents.
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高影响因子
Reaction Kinetics Mechanisms and Catalysis
·
2019
·Vol. 128
·期 2
·1065-1077
·
IF 1.428
Yu Qifan,Liu Xuesong,Chen Hongfeng,Liu Shuang,Jiang Peng
The regeneration mechanism of sulfated Cu/SAPO-34 catalysts in reducing atmospheres (5% H 2 /Ar and NH 3 /Ar at 600 °C) was investigated by using a series of characterization methods. Hydrogen regeneration improved the catalysts’ NH 3 -SCR activity from 150 to 550 °C remarkably, while ammonia regeneration exhibited relatively less obvious promotion effect. The TPR of hydrogen and EPR spectra data show that the regeneration process affects the amount and the coordination of the active isolated Cu 2+ species significantly. The desulfation increases the amount of isolated copper ions and improves the catalytic activity of SCR.
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高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2019
·
IF 8.355
Han Jiang,Bin Guan,Xuesong Peng,Reggie Zhan,He Lin,Zhen Huang
This study focuses on investigating the influence of ion-exchange method (ION-F and ION-A) and one-pot method (ONE-F and ONE-A) on catalytic properties and hydrothermal stability of Cu/SSZ-13. It was found that ONE-F catalyst showed better SCR activity, especially at low temperature range below 400 °C. After hydrothermal aging, ION-A exhibited higher low temperature efficiency than ONE-A. The effect of synthesis method on the physicochemical structure, acidity intensity, and Cu species migration or transformation of the fresh and aged Cu/SSZ-13 catalysts were comprehensively characterized by NH 3 -TPO, H 2 -TPR, NH 3 -TPD, ICP, XRF, BET, XRD, SEM, and TEM. ONE-F has more isolated Cu 2+ sites, higher ratio of active sites Cu 2+ -2Z/[Cu(OH)] + -Z, more Lewis acid sites, and smaller particle size than ION-F. However, hydrothermal aging had severe effect on Cu/SSZ-13 prepared by one-pot method, leading to particle aggregation and decrease of active copper sites. According to NH 3 -SCR kinetic studies, smaller particle size and more uniformly distributed active sites over ONE-F resulted in less effect of pore diffusion limitation. Furthermore, in situ DRIFTS results indicated that more monodentate nitrates adsorbed sites and Lewis acid sites existed in ONE-F. On the other hand, monodentate nitrates were identified to be the most active nitrate species, and Lewis acid sites were ascertained to be more active than Brønsted acid sites. Therefore, ONE-F showed more excellent SCR performance than ION-F. However, hydrothermal aging resulted in loss of majority of nitrate adsorbed sites and acid sites over catalyst prepared by one-pot method, leading to lower SCR performance. In conclusion, Cu/SSZ-13 prepared by ion-exchange method has higher hydrothermal stability, however, fresh Cu/SSZ-13 prepared by one-pot method has excellent catalytic properties.
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Journal of Materials Chemistry A
·
2019
·Vol. 7
·期 28
·16969-16978
·
IF 10.733
Tianxing Wu,Miaomiao Han,Xiaoguang Zhu,Guozhong Wang,Yunxia Zhang,Haimin Zhang,Huijun Zhao
Deeply understanding the electrochemical activation and inactivation processes of an electrocatalyst is critically important for establishing a high-efficiency nitrogen reduction reaction (NRR) to synthesize an NH3 system. Here we report the utilization of a facile vapor-phase hydrothermal (VPH) method to directly grow ultrafine Nb3O7(OH) nanoparticles on commercial carbon fiber cloth (Nb3O7(OH)/CFC) for the NRR. The results demonstrate that the Nb3O7(OH)/CFC can afford an average NH3 yield rate of 622 μg h−1 mgcat.−1 with a high faradaic efficiency (FE) of 39.9% at −0.4 V versus the reversible hydrogen electrode (RHE) in 0.1 M Na2SO4 electrolyte (pH = 6.1) within 30 min of the NRR, surpassing the performance of most recently reported aqueous-based NRR electrocatalysts. The experimental and theoretical calculation results reveal that the in situ electrochemically converted NbO from Nb3O7(OH) during the NRR is the catalytic active phase with a N2 adsorption free energy of −0.97 eV; however with a reaction time over 30 min, the generated active *N atoms in the *N–NH3 → *N + NH3 hydrogenation step during the NRR are thermodynamically favourable for binding to the oxygen vacancies of NbO to form oxygen-containing NbN0.64 with reduced N2 adsorption free energy (−0.32 eV), resulting in significantly decreased NRR activity. Our studies suggest that although NbO possesses high NRR activity, it may not be a suitable NRR electrocatalyst, owing to easy formation of low active niobium oxynitride during the NRR.
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Nano Research
·
2019
·Vol. 12
·期 5
·1093-1098
·
IF 8.515
Huang Hong,Gong Feng,Wang Yuan,Wang Huanbo,Wu Xiufeng,Lu Wenbo,Zhao Runbo,Chen Hongyu,Shi Xifeng,Asiri Abdullah M.,Li Tingshuai,Liu Qian,Sun Xuping
Currently, industrial-scale NH 3 production almost relies on energy-intensive Haber-Bosch process from atmospheric N 2 with large amount of CO 2 emission, while low-cost and high-efficient catalysts are demanded for the N 2 reduction reaction (NRR). In this study, Mn 3 O 4 nanoparticles@reduced graphene oxide (Mn 3 O 4 @rGO) composite is reported as an efficient NRR electrocatalyst with excellent selectivity for NH 3 formation. In 0.1 M Na 2 SO 4 solution, such catalyst obtains a NH 3 yield of 17.4 μg·h −1 ·mg −1 cat . and a Faradaic efficiency of 3.52% at −0.85 V vs. reversible hydrogen electrode. Notably, it also shows high electrochemical stability during electrolysis process. Density functional theory (DFT) calculations also demonstrate that the (112) planes of Mn 3 O 4 possess superior NRR activity.
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高影响因子
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