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柴油机低温工况下SCR尿素喷射及nh分布特性研究

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农业装备与车辆工程 2024年

作者：和志高杨树启郭宇辰杨继孔杨辉内蒙古农业大学德宏职业学院滇西应用技术大学

在柴油机加装后处理系统DOC+CDPF+SCR的试验研究基础上，构建并开展SCR三维CFD数值模拟，研究了尿素喷射过程中液滴的生成扩散和水解蒸发，对比分析了不同低温工况下nh3分布特性和nh3分布均匀度对NOx转化效率的影响。结果表明，在低温... 详细信息

在柴油机加装后处理系统DOC+CDPF+SCR的试验研究基础上，构建并开展SCR三维CFD数值模拟，研究了尿素喷射过程中液滴的生成扩散和水解蒸发，对比分析了不同低温工况下nh3分布特性和nh3分布均匀度对NOx转化效率的影响。结果表明，在低温工况下随着尿素喷射量亦增大，混合器前后区域催化器内表面形成较多的尿素壁膜，持续尿素喷射易产生尿素结晶；低温工况混合器和整流器对气体流动有明显的扩散作用，但随着气流量增大nh3分布集中在载体外侧区域，导致外侧发生nh3逃逸量较高；在不同低温工况下，载体入口面nh3分布均匀度的增大，有效提高了NOx转化效率，减小了nh3逃逸量及低温下尿素结晶的可能性。

关键词：低温工况尿素壁膜 nh 分布均匀度尿素结晶

Single-atom catalysts for electrochemical N2 reduction to nh3

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Rare Metals 2023年第4期42卷 1075-1097页

作者： Muhammad Saqlain lqbal Zhi-Bo Yao Yu-Kun Ruan Ramsha Iftikhar Lei-Duan Hao Alex W.Robertson Syed Muhammad Imran Zhen-Yu Sun Department of Chemical Engineering COMSATS University Islamabad State Key Laboratory of Organic-Inorganic Composites College of Chemical EngineeringBeijing University of Chemical Technology Department of Chemistry Government College University Faisalabad Department of Physics University of Warwick

The increasing demand for clean energy and growing concerns regarding environmental sustainability have led to greater attention devoted toward the production of clean fuels via green chemistry.In this respect,ammonia is a green alternative to fossil fuels and can serve as a clean energy source.There is now great interest in realizing the electrochemical reduction in atmospheric nitrogen(N2) for cheap,environmentally friendly and reliable ammonia(nh3) production worldwide.However,the robustness of the triple bond in N2 and the low efficiency of candidate catalysts limit the utility of this conversion.Single atom catalysts have been found to be more effective than nanoparticles due to their unique properties,and thus have been studied extensively for the nitrogen reduction reaction.In this review,we have covered the recent advances in design and synthesis of noble metal and non-noble metal single atom catalysts for the electrochemical reduction in nitrogen during the years 2018-2022.The catalyst efficiencies,with reference to coordination preferences and theoretical studies have been discussed.Moreover,we also provide insights into the current challenges and some considerations for further future studies.

关键词： N 2 reduction Single atom catalyst (SAC) Electrocatalysis nh 3

Assessment of the crucial factors influencing the responses of ammonia and nitrous oxide emissions to controlled release nitrogen fertilizer: A meta-analysis

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Journal of Integrative Agriculture 2023年第11期22卷 3549-3559页

作者： Lü Hui-dan WANG Xi-ya PAN Zhao-long ZHAO Shi-cheng State Key Laboratory of Efficient Utilization of Arid and Semi-arid Arable Land in Northern China/Key Laboratory of Plant Nutrition and Fertilizer Ministry of Agriculture and Rural Affairs/Institute of Agricultural Resources and Regional PlanningChinese Academy of Agricultural SciencesBeijing 100081P.R.China

Reducing ammonia(nh3) and nitrous oxide(N2O) emissions have great effects on mitigating nitrogen(N) nutrient loss and greenhouse gas emissions. Controlled release urea(CRU) can control the N release rate, which reduces reactive N loss and increases nitrogen use efficiency relative to conventional urea(CU). However, the crucial factors influencing the responses of nh3and N2O emissions to CRU relative to CU are still unclear. In this study, we evaluated the responses of nh3and N2O emissions to CRU based on collected field data with a meta-analysis. CRU reduced the nh3and N2O emissions by 32.7 and 25.0% compared with CU, respectively. According to subgroup analysis, CRU presented better mitigation of nh3and N2O emissions in soils with pH 6.5–7.5(–47.9 and –23.7%) relative to either pH7.5(–29.3 and –17.3%), and in the rice season(–34.8 and –29.1%) relative to the wheat season(–19.8 and –22.8%). The responses of nh3and N2O emissions to CRU increased from rainfed(–30.5 and –17.0%) to irrigated(–32.5 and –22.9%), and then to paddy(–34.8 and –29.1%) systems. In addition, the response of N2O emission mitigation increased with increases in soil total nitrogen(TN);however, soil TN did not significantly affect the response of nh3volatilization. The reduction in nh3emission was greater in sandy-textured soil(–57.7%) relative to loam-textured(–32.9%) and clay-textured(–32.3%) soils, whereas soil texture did not affect N2O emission. Overall, CRU was a good option for reducing the nh3and N2O emissions relative to CU in agricultural production. This analysis improves our understanding of the crucial environmental and management factors influencing the mitigation of nh3and N2O emissions under CRU application, and these site-specific factors should be considered when applying CRU to reduce reactive N loss and increase NUE.

关键词： controlled release urea nh volatilization N O emission environmental factor management practice

Fluorination reaction of UO3 and electrochemical preparation of UO2

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Chinese Chemical Letters 2022年第7期33卷 3435-3438页

作者： Rugeng Liu Yangyang Meng Wenjing Ji Wei Han Mei Li Yang Sun Key Laboratory of Superlight Materials and Surface Technology Ministry of Education College of Material Science and Chemical Engineering Harbin Engineering University

In this work, a technique was proposed to prepare UO2from UO3by the two processes of fluorination reaction of UO3with nh4HF2and electrochemical reduction of UO22+for the recycle uranium. The feasibility of fluorination reaction was firstly confirmed using thermodynamic calculation; then, the products were analyzed using XRD, Raman and fluorescence to be UO2F2. The fluorination mechanism was inferred to be UO3（s） + nh4HF2→（nh4）3UO2F5→ nh4（UO2）2F5→ UO2F2. The redox behavior of UO22+on W electrode was investigated by cyclic voltammetry and square wave voltammetry, which indicated that UO22+was reduced to UO2via a two-step single electron transfer with diffusion-controlled. The diffusion coefficient of UO22+was calculated to be 6.22 × 10-5cm/s. The disproportionation reaction of UO2+was observed, and the relationship between the disproportionation reaction and scan rate was discussed.Moreover, the electrochemical fabrication of UO2was conducted by electrolysis at-0.8 V, and the product was analyzed by XRD, SEM and EDS to be UO2. ICP-AES results showed that the extraction efficiency of UO2could reach 98.53%.

关键词： UO 3 Fluorination reaction nh 4 HF 2 Electrochemical formation UO 2

氨煤混燃过程中nh/煤焦/O_(2)异相体系N氧化的分子机理

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煤炭学报 2023年第2期48卷 1037-1046页

作者：陈萍王莹汪辉春蒋博宇顾明言樊建人安徽工业大学能源与环境学院安徽马鞍山243002 浙江大学能源清洁利用国家重点实验室浙江杭州310000

为了实现双碳目标,降低煤电碳排放势在必行。无碳燃料氨与煤混烧被认为是降低火电碳排放的有效途径之一。而氨作为N源,增加了氨煤混燃NOx排放量升高的可能性,因此,深入研究氨煤混燃NO生成机理对实现氨煤混燃低碳低氮燃烧十分关键。采用... 详细信息

为了实现双碳目标,降低煤电碳排放势在必行。无碳燃料氨与煤混烧被认为是降低火电碳排放的有效途径之一。而氨作为N源,增加了氨煤混燃NOx排放量升高的可能性,因此,深入研究氨煤混燃NO生成机理对实现氨煤混燃低碳低氮燃烧十分关键。采用量子化学方法探究了当nh3以nh形式存在时氨煤混燃N的氧化机理,并采用波函数分析nh和O_(2)在煤表面的吸附行为。计算结果表明,nh在C5表面吸附形成中间体IM1的过程为放热过程,放热量高达754.79 kJ/mol,且C原子为电子供体而失电子,nh为电子受体而得电子,促进C—N键键合。进一步探究O_(2)以不同方式吸附时nh/煤焦/O_(2)体系的反应机理,得出nh/煤焦/O_(2)共燃体系首先发生nh在煤焦表面的氧化,随后煤焦表面残余氧或体系中O_(2)将煤焦-N进一步氧化。nh/煤/O_(2)异相体系中nh通过不同反应路径生成氧化产物NO、NO_(2)和HNO,对应决速步能垒分别为120.67、323.37和193.50 kJ/mol,说明氨-N/煤-N生成NO的过程更易进行。动力学结果表明,各温度下生成NO的决速步速率明显高于NO_(2),且随着温度升高,生成NO的决速步速率与HNO的逐渐接近。nh氧化产物释放后,残留在煤焦表面氧进一步与C结合成CO释放,实现了共燃体系氨燃料中N和煤粉中C的氧化。随后煤焦-N与体系中O_(2)发生异相氧化,实现煤焦-N向NO的转化。在微观层面揭示了氨燃烧生成NO过程中重要过渡产物HNO形成的分子机理,明晰了另一氧化产物NO_(2)的生成路径,为发展氨煤的混合燃烧机理提供理论支撑和数据参考。

关键词：氨煤混烧 nh 煤焦-N NO HNO

Intrinsic Instability of the Hybrid Halide Perovskite Semiconductor CH3nh3PbI3

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Chinese Physics Letters 2018年第3期35卷 52-57页

作者：张越宇陈时友许朋向红军龚新高 Aron Walsh 魏苏淮 Key Laboratory for Computational Physical Sciences(MOE) State Key Laboratory of Surface Physicsand Department of PhysicsFudan UniversityShanghai 200433 Key Laboratory of Polar Materials and Devices(MOE) East China Normal UniversityShanghai 200241 Center for Sustainable Chemical Technologies and Department of Chemistry University of BathBath BA2 7AYUK Beijing Computational Science Research Center Beijing 100094

The organic-inorganic hybrid perovskite CH3nh3PbI3 has attracted significant interest for its high performance in converting solar light into electrical power with an efficiency exceeding 20%. Unfortunately, chemical stability is one major challenge in the development of CH3nh3PbI3 solar cells. It was commonly assumed that moisture or oxygen in the environment causes the poor stability of hybrid halide perovskites, however, here we show from the first-principles calculations that the room-temperature tetragonal phase of CH3nh3PbI3 is thermodynamically unstable with respect to the phase separation into CH3nh3I ＋ PbI2, i.e., the disproportionation is exothermic, independent of the humidity or oxygen in the atmosphere. When the structure is distorted to the low-temperature orthorhombie phase, the energetic cost of separation increases, but remains small. Contributions from vibrational and configurational entropy at room temperature have been considered, but the instability of CH3nh3PbI3 is unchanged. When I is replaced by Br or CI, Pb by Sn, or the organic cation CH3nh3 by inorganic Cs, the perovskites become more stable and do not phase-separate spontaneously. Our study highlights that the poor chemical stability is intrinsic to CH3nh3PbI3 and suggests that element-substitution may solve the chemical stability problem in hybrid halide perovskite solar cells.

关键词： nh Pb CH Intrinsic Instability of the Hybrid Halide Perovskite Semiconductor CH3nh3PbI3

超低排放改造推广及nh_(3)减排对京津冀冬季环境效益研究

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环境科学学报 2022年第5期42卷 444-453页

作者：焦小淼任世华张伟刘潇煤炭科学研究总院有限公司科技支持中心北京100013 北京低碳清洁能源研究院北京102211 北京大学物理学院大气与海洋科学系北京100871 赛迪顾问股份有限公司北京100081

为量化京津冀(BTH)地区超低排放(ULE)改造推广应用潜在的环境效益,基于GEOS-Chem大气化学模型,设计了2个全国情景和6个区域情景,从区域大气输送、超低排放改造在燃煤电厂(CPPs)、工业燃煤(ICB)推广及控制nh;排放等方面进行研究.结果表明... 详细信息

为量化京津冀(BTH)地区超低排放(ULE)改造推广应用潜在的环境效益,基于GEOS-Chem大气化学模型,设计了2个全国情景和6个区域情景,从区域大气输送、超低排放改造在燃煤电厂(CPPs)、工业燃煤(ICB)推广及控制nh;排放等方面进行研究.结果表明:(1)全国燃煤电厂完成ULE改造,使得京津冀地区2015年1月PM_(2.5)浓度下降3.2%(2.4μg·m^(-3)),如只是京津冀地区燃煤电厂完成ULE改造,可使京津冀地区PM_(2.5)浓度降低1.1%(0.8μg·m^(-3)),可知区域联防联控对雾霾的治理具有重要意义;(2)在京津冀地区燃煤电厂完成ULE改造的基础上,工业燃煤完成ULE改造、nh;排放减少30%和50%,可使得京津冀地区PM_(2.5)浓度分别降低5.4%(3.5μg·m^(-3))、4.7%(4.0μg·m^(-3))和7.7%(5.7μg·m^(-3)),可知工业燃煤的ULE改造和nh;减排,均可显著降低PM_(2.5)的浓度;(3)在京津冀地区燃煤电厂和工业燃煤都完成ULE改造的基础上,nh;排放分别减少30%和50%,可使得PM_(2.5)浓度分别降低8.5%(6.3μg·m^(-3))和11.2%(8.3μg·m^(-3)),可知工业燃煤的ULE改造降低常规污染物或nh;减排控制均能显著降低PM_(2.5)浓度,为更好地降低京津冀地区PM_(2.5)的浓度应综合考虑工业燃煤的ULE改造、nh;减排及区域联防联控,可通过经济代价和环境效益分析确定最佳的雾霾治理方案.

关键词：超低排放(ULE) 雾霾污染 GEOS-Chem模拟 nh 减排燃煤电厂工业燃煤京津冀地区

A STUDY ON CONFIGURATION-ACTIVITY RELATIONSHIP OF DIAMMINEDICHLOROPLATINUM (Ⅱ) BY THE PSEUDOPOTENTIAL VALENCE ELECTRON-ONLY ab initio CALCULATION METHOD

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Science China Chemistry 1987年第9期30卷 922-930页

作者：陈凯先吴吉安嵇汝运 Shanghai Institute of Materia Medica Academia Sinica

We investigated the cis- and trans-isomers of Pt（nh）Cland [Pt（nh）]using a quantum chemical non-empirical calculation method, the pseudopotcntial valence electron only ah initio method. The electronic structure and electrostatic potential counter maps were in turn determined through the wave functions so obtained. There was a sharp difference between the dipole moments of the cis- and trans-isomers. The electrostatic counter maps of the isomers also had remarkably different features. Based on the interaction between the platinum （Ⅱ） coordination compound and the base pairs of nucleic acid, the difference in antitumour activity of the isomeric compounds was discussed, It is pointed out that the key factor for antitumour activity is that the platinum （Ⅱ） coordination compound must be mutually complementary with the target acceptor in both configuration and bonding activity. This mutualcomplementary requirement includes a bonding ability of the platinum complex with two negative centers i

关键词： STO A STUDY ON CONFIGURATION-ACTIVITY RELATIONSHIP OF DIAMMINEDICHLOROPLATINUM BY THE PSEUDOPOTENTIAL VALENCE ELECTRON-ONLY ab initio CALCULATION METHOD nh Pt

Fluorescence Enhancement of Metal-Capped Perovskite CH3nh3PbI3 Thin Films

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Chinese Physics Letters 2017年第9期34卷 78-81页

作者：孙鹏俞伟伟潘晓航魏威孙艳袁宁丁建宁赵文超陈鑫戴宁 School of Materials Science and Engineering Jiangsu Collaborative Innovation Center of Photovoltaic Science and Engineering Jiangsu Province Cultivation Base for State Key Laboratory of Photovoltaic Science and Technology Changzhou University Changzhou 213164 National Laboratory for Infrared Physics Shanghai Institute of Technical Physics Chinese Academy of Sciences Shanghai 200083

We fabricate nano-structural metal films to improve photoluminescence of perovskite films. When the perovskite film is placed on an ammonia-treated alumina film, stronger photoluminescence is found due to local field en- hancement effects. In addition, the oxide spacer layer between the metal （e.g., AI, Ag and Au） substrate and the perovskite film plays an important role. The simulations and experiments imply that the enhancement is related to surface plasmons of nano-structural metals.

关键词： In Al Fluorescence Enhancement of Metal-Capped Perovskite CH3nh3PbI3 Thin Films nh CH