COMBUSTION AND FLAME
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2021
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IF 4.185
Ye Wu,Jian Mei,Tianyi Cai,Wei Wang,Hang Zhu,TianLi Sun,Dong Liu
Ammonia is considered to be a green energy due to its carbon-free footprint, high energy density, cheap transport costs and so on. However, the problem of NO x (mainly NO/NO 2 ) emissions especially at high temperature (>800 °C) inhibits the energy utilization progress of NH 3 (Such as NH 3 combustion). So, catalytic combustion of NH 3 is supposed to be a promising method to solve this problem but there is a rare report on that. The NO x emissions or N 2 selectivity performances in the NH 3 oxidation process with different catalyst was conducted with Density functional theory (DFT) and experimental studies. Results showed that, when Fe 2 O 3 was used as catalyst, the conversion efficiency of NH 3 was 96.2%, and the selectivity of N 2 was 97.7%, which was higher than oxidation of NH 3 without catalyst. DFT simulation showed that NH 3 and O 2 can be separately adsorbed on Fe (top) of Fe 2 O 3 (001), the adsorption of NH 3 and O 2 were enhanced when they were put on Fe (top) of Fe 2 O 3 (001) at the same time. Meanwhile, the length of inter-atomic bond increased thus creating oxygen vacancy , which promoted the oxidation of NH 3 . Finally, a Ni modified Fe-based catalyst (NiO10%/Fe 2 O 3 30%/Al 2 O 3 60%), full of oxygen vacancy (confirmed with X-ray photoelectron spectroscopy (XPS)), was fabricated with impregnation method. The adsorption of NH 3 and O 2 were further enhanced (confirmed by DFT simulation), the NH 3 conversion efficiency and the N 2 selectivity were stably improved to 96.8% and 100%.
研究领域:
化学工程
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环境科学
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催化材料
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DOI
高影响因子
Journal of Environmental Chemical Engineering
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2023
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IF 7.7
Chenxi Wang,Gang Lv,Yunqiang Li,Ye Liu,Chonglin Song
The selective catalytic reduction of nitrogen oxides by methane (CH 4 /NO X -SCR) is a potential technique for the abatement of the NO X emissions from lean-burn GDI engines, due to the excellent thermal stability of CH 4 . This work focuses on the promotion of In/SSZ-13 catalysts by Ce modification for the CH 4 /NO X -SCR performance at high temperatures. A series of In/SSZ-13 and Ce-In/SSZ-13 catalysts were prepared using the wetness impregnation method. The effects of Ce modification on the catalytic performance were analysed in detail using the scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, ultraviolet-visible diffuse reflectance spectrum and temperature-programmed desorption/reduction techniques. The results show that the Ce modification significantly enhances the high-temperature activity of the In/SSZ-13 catalysts for the NO X -SCR reaction, especially for the 5 wt% Ce-15 wt% In/SSZ-13 sample which has more than 75% NO X conversion at 390–700 °C. In addition, the Ce modification enhances the water vapor tolerance of the catalyst sample. The Ce modification increases not only the concentration of surface chemisorption oxygen species, but also the relative amount of InO + species which serve as the main active sites for CH 4 activation. Furthermore, the incorporation of Ce into In/SSZ-13 greatly promotes NO X adsorption on the catalyst surface. Most importantly, the Ce modification makes In species well-dispersed on the catalyst surface and thus suppresses the formation of bulk In 2 O 3 species which are more active for the CH 4 non-selective oxidation. The combination of all these effects results in the Ce-In/SSZ-13 samples with the superior catalytic activity .
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CHEMICAL ENGINEERING JOURNAL
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2022
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IF 16.744
Guobo Li,Shipeng Ding,Xueyan Hou,Kai Shen,Shule Zhang,Yaping Zhang
Controlling chlorobenzene (CB) and NO x emissions via catalytic oxidation and selective catalytic reduction necessitates high redox performance catalysts, and construction of active centers with multiple adsorption centers towards reactants is prerequisite for developing such catalysts. Herein, the electronic structure and active centers of the PdV/TiO 2 bimetallic catalyst were modulated by Sb modification. The neighboring antimony (Sb) promoted the charge transfer between V and Pd centers, and suppressed the adsorption of SO 2 on active sites, thus accelerating CB/NO x conversion and significantly avoiding the deposition of sulfur species on the active centers, especially the Pd species. The detailed plausible CB/NO x catalytic removal pathway (CB free → CB ads → C 6 H 5 ads + Cl ads + O species (O latt and O ads ) → C x H y O z + Cl ads + Brønsted → CO 2 + H 2 O + HCl on SbPdV/TiO 2 catalyst surface was further established. This research provided a strategy for the development of improved CB catalytic oxidation + selective catalytic reduction (CBCO + SCR) catalysts by tuning the electronic structure of active centers.
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高影响因子
PROCESS SAFETY AND ENVIRONMENTAL PROTECTION
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2022
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IF 7.926
Shuangli He,Jinghang Ren,Peng Cao
Low-temperature selective catalytic reduction (SCR) is effective and promising for converting NO x in flue gas into N 2 , with wide application prospects. However, low-temperature denitration (DeNO x ) catalysts are susceptible to SO 2 and H 2 O poisoning. Here, we prepared a monolithic Mn-Fe-Ce/Al 2 O 3 catalyst that exhibited excellent DeNO x performances at low temperatures. At 110 °C, the NO conversion rate of the catalyst was> 90%, exhibiting excellent resistances to H 2 O and SO 2 ·H 2 O and SO 2 are introduced at the same time, the efficiency is as high as 73%. Furthermore, The catalyst has a porous structure with abundant chemisorbed oxygen spices and exposed active, the reaction pathway on the catalyst proved to be the L-H mechanism based on in situ DRIFTS. This study also explored the mechanisms of low-temperature SCR catalyst poisoning by SO 2 and H 2 O, providing insights into the effects of SO 2 and H 2 O and theoretical support for the development of poisoning-resistant low-temperature SCR catalysts.
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CHEMOSPHERE
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2022
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IF 8.943
Junxiong Zhao,Qifeng Wei,Dongkui Bi,Lijuan Liu,Shanshan Wang,Xiulian Ren
Marine engine exhaust emissions are increasingly harmful to the natural environment and human health and must be controlled. A self-synthesized amide (BAD, C 12 H 25 NO) in the laboratory shows a strong absorption capacity of nitric acid and nitrous acid , which may solve the problem that only using chlorine-based oxidant as an absorbent cannot completely absorb or retain NO 2 produced by NO oxidation in previous studies. Based on Multiwfn and VMD (Visual Molecular Dynamics) program calculation, the formation mechanism of hydrogen bonds between BAD with nitric acid and nitrous acid was revealed by electrostatic potential (ESP) analysis and further confirmed by FT-IR (Fourier transform infrared spectroscopy) spectra research. Subsequently, simultaneous removal of SO 2 and NO X from simulated flue gas was carried out by using NaClO/BAD as a two-phase composite absorbent, and the maximum removal efficiencies of SO 2 and NO X were 98.9% and 86.6%, respectively. The recycling experiments and the engineering experiments showing that NaClO/BAD can solve the problem of absorption of NO 2 , and it can be a promising composite absorbent in wet desulfurization and denitrification of marine engine exhaust gas in practical applications.
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PubMed
高影响因子
CHEMICAL ENGINEERING JOURNAL
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2021
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IF 13.273
Liyuan Duan,Guoqiang Li,Shuting Zhang,Hongyu Wang,Yongle Zhao,Yongfa Zhang
In this study, graphitized carbon nitride photocatalysts were successfully prepared by using the desulfurized waste liquid extracting salt from coking plants. The NO x removal efficiency of g-C 3 N 4 synthesized using ammonium thiocyanate (NH 4 SCN), ammonium thiosulfate ((NH 4 ) 2 S 2 O 3 ) and ammonium sulfate ((NH 4 ) 2 SO 4 ) with different mass ratios were evaluated. The results showed that due to the addition of (NH 4 ) 2 S 2 O 3 and (NH 4 ) 2 SO 4 a large amount of sulfur-containing gas was released during pyrolysis, which significantly increased the specific surface area and pore volume of the photocatalysts. The release of sulfur-containing gas also resulted in the incorporation of sulfur, and due to this doping process the band gap of the photocatalyst was widened to 2.94 eV, thus enhancing its visible light response. C vacancies were formed in the hepazine ring, which increased the electron density around the N–(C) 3 bridge bond and formed an electron trapping center, thus inhibiting the recombination of charge carriers. The photocatalysts had increased O 2 adsorption capacity and increased number of amino groups on their surface. This facilitated the rapid generation and consumption of reactive oxygen species, inhibited the accumulation of NO 2 on the surface, reduced the production of NO 2 , thus improving the NO x removal efficiency of the photocatalysts. The principle of using “waste for waste control” was achieved, and a new method for nitrogen oxide removal was provided.
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APPLIED CATALYSIS B-ENVIRONMENTAL
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2020
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IF 16.683
Guobo Li,Kai Shen,Ling Wang,Yaping Zhang,Hongqiang Yang,Peng Wu,Bing Wang,Shule Zhang
Development of an efficient synergistic degradation technology to prevent the emission of chlorinated organics and NO x from industrial sources without forming harmful by–products, is a major challenge in environmental chemistry. The designed multi–active center catalyst (PdV/TiO 2 ) showed excellent CB/NO synergistic removal conversion efficiency and target product selectivity. Experimental and DFT calculation results indicated that Pd was the common center for adsorption of CB, O 2 , NH 3 and NO x molecules. The O vacancies (VO x –1 and TiO x –1 ) generated during the CB ring opening process was conducive to adsorption of reaction gas molecules, accelerating CBCO and NH 3 –SCR reaction. The adsorbed NH 3 species would dissociate H protons to provide Brønsted acidic sites necessary for Cl conversion. O vacancies structure was easier to be restored by reoxidation with the participation of NO 2 . Certain synergistic effect in the removal of CB and NO on the multi–active center catalyst surface was found.
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VACUUM
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2024
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IF 3.8
Hailin Zheng,Min Zheng,Xianxing Huang,Mingjie Liang,Kang Li
Chemical-looping combustion (CLC) technology is considered a promising combustion method with inherent CO 2 capture. In this study, the sol-gel method and combustion synthesis were employed to produce precursor materials (P) of CuO-based oxygen carriers (OCs). The effects of vacuum drying conditions on both NO x emissions from precursor combustion and oxygen carrier cycle reaction characteristics were investigated. Vacuum-dried precursors emitted less NO x during the precursor calcination process. At a heating rate of 1 °C/min, the vacuum-dried precursors exhibited an average reduction of 24.13 % in NO x emissions compared with those prepared through atmospheric pressure drying. An increased amount of Cu 2 (OH) 3 NO 3 in the precursor results in greater heat release during the self-propagating high-temperature combustion synthesis used to synthesize the oxygen carrier. Furthermore, the complete combustion of the nitrogen-containing precursor leads to a reduction in the emission of NO x . CuO-based OCs exhibited stable redox reactions over 10 cycles. Vacuum drying enhanced CH 4 conversion and CO 2 yield of OC1 by 14.04 % and 13.21 %, respectively, compared to atmospheric pressure drying. The results indicate that the CuO-based OCs obtained through vacuum-dried significantly enhance redox properties. This study shows that vacuum-dried reduces NO x emissions from nitrogen precursors and enhances the cyclic efficiency of OCs from precursor combustion.
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高影响因子
JOURNAL OF CATALYSIS
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2024
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IF 6.5
Ruoyuan Li,Aixia Li,Junhua Li,Yao Wang,Zhiming Liu
Selective catalytic reduction of NO x by CO (CO-SCR) in the presence of O 2 is challenging because in this process CO is prone to being oxidized by O 2 , thus inhibiting NO x reduction by CO. Furthermore, SO 2 typically leads to the deactivation of the CO-SCR catalyst. Herein, a significant promoting effect of SO 2 on Ir/SiO 2 catalyst for the CO-SCR of NO x in the presence of O 2 is reported. In-situ X-ray Absorption Fine Structure (XAFS) and X-ray photoelectron spectroscopy (XPS) analysis showed that SO 2 does not affect the chemical nature of Ir 0 under reaction conditions. However, SO 2 can be oxidized to sulfate and deposit on the catalyst surface. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) analysis demonstrated that the presence of SO 2 can inhibit the CO + O 2 reaction, thus leaving more CO available to reduce NO x over the active Ir 0 sites. As a result, the reduction of NO x is remarkably promoted even in the presence of O 2 and SO 2 .
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高影响因子
JOURNAL OF SOLID STATE CHEMISTRY
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2025
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IF 3.5
Fang-Ting Wang,Qing-Yun Xie,Huan Jiao,Ling Xu
The accumulation of nitrate/nitrite (NO x – ) in wastewater poses a threat on ecological safety. Electrocatalytic NO x – reduction to ammonia (NO x – RR) is feasible to realize green ammonia production. This work developed a 2D copper metal-organic framework of Cu-BDC (H 2 BDC = 1,4-benzene dicarboxylic acid) as an efficient electrocatalyst for NO x – RR, exhibiting high-performance with the NH 3 yield of 71.20 μmol‧h −1 ‧cm −2 and a Faraday efficiency of 80.9 % at −0.746 V ( vs. RHE) for NO 2 − RR, and the NH 3 yield of 130.16 μmol‧h −1 ‧cm −2 and a Faraday efficiency of 67.42 % at −0.946 V ( vs. RHE) for NO 3 − RR. Isotope labelled 14 NO 3 − and 15 NO 3 − produced 14 NH 4 + and 15 NH 4 + , supporting the formation of NH 3 comes from the NO 3 − RR. In three NO x – RR cycles, all NH 3 yields and Faraday efficiencies show a slight change, demonstrating an excellent electrocatalytic stability in NO x – RR. Our work provides a new material platform for the elimination of nitrate and nitrite through electrocatalytic reduction.
研究领域:
电化学
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环境科学
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催化
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材料科学
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化学工程
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高影响因子
CHEMICAL ENGINEERING JOURNAL
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2023
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IF 15.1
Beilong Lin,Ziyang Guo,Jianhan Li,Gaofei Xiao,Daiqi Ye,Yun Hu
It is a major challenge to achieve effective synergistic reduction of NO x and VOCs in coal-fired flue gas under complex working conditions. In this work, V-Cu bimetallic oxide catalysts with different supports were designed. V1-Cu5 bimetallic oxide supported on TiO 2 showed significantly higher activity for simultaneous toluene oxidation and NO x reduction than that supported on ZSM-5, SiO 2 and γ-Al 2 O 3 . Meanwhile, it exhibited excellent stability and anti-poisoning performance, and could block the formation of toxic polycyclic aromatic hydrocarbons in by-products. Compared with ZSM-5, SiO 2 and γ-Al 2 O 3 , TiO 2 as support was conducive to the formation of abundant acidic sites and oxygen vacancies. In addition, the strong interaction between the metal active sites and TiO 2 accelerated the electron transfer from Cu to adsorbed O 2 , thus promoting the formation of active O 2− . This work can provide guidance for the development of catalysts designed for the simultaneous catalytic removal of NO x and VOCs.
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MICROPOROUS AND MESOPOROUS MATERIALS
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2022
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IF 5.876
Yang Zhang,Baihe Sun,Lin Jiang,Jiahui Fan,Fangjie Qin,Zhuo Liu,Jue Wang,Kan Kan,Keying Shi
A facile polymer heat treatment and reflux method are used for developing growth of flower-like BiOCl (BiOCl NFs) on 3D honeycomb-like N-doped graphitic carbon (N-GC) to form BiOCl/N-GC composites. The N-GC hierarchical structure effectively heightened the dispersion of BiOCl NFs, which increased the contacted area for the NO x gas molecule. Benefiting from the hierarchical structure, the (102) plane of BiOCl has a suitable adsorption energy for NO x , synergistic effect of large specific surface area and mesopores of N-GC, the formation of p-p heterojunctions , Bi–C interfacial bond, N-doping and the role of chemisorbed oxygen. The BiOCl/N-GC composites have satisfactory response and selectivity for NO x gas at room temperature. It reveals an exceptionally excellent response and response time of 52.54 and 3.2 s for NO x gas. It also exhibits a low detection limit (10 ppb) and a long-stability of 12 weeks. Thus, the BiOCl/N-GC nanocomposites are one of the most potential materials in gas sensor.
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