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Catalytic urea hydrolysis by composite metal oxide catalyst towards efficient urea-based scr process:performance evaluation and mechanism investigation

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Frontiers of Environmental Science & Engineering 2023年第5期17卷 67-80页

作者： Yuchen Li Zhen Chen Xiangyu Zhang Kun Yang Lidong Wang Junhua Li MOE Key Laboratory of Resources and Environmental Systems Optimization Department of Environmental Science and EngineeringNorth China Electric Power UniversityBeijing 102206China State Key Joint Laboratory of Environment Simulation and Pollution Control School of EnvironmentTsinghua UniversityBeijing 100084China Xi’an Thermal Power Research Institute Co. Xi’an 710032China

As a promising option to provide gaseous NH_(3) for scr system,catalytic urea hydrolysis has aroused great attention,and improving surface area and activity of catalysis are the crucial issues to be solved for efficient urea ***,a composite metal oxide(TiO_(2)@Al_(2)O_(3))catalyst was prepared by a simple hydrothermal method,with mesoporous alumina(γ-Al_(2)O_(3))as *** results verify the mesoporous structure and submicron cluster of TiO_(2)@Al_(2)O_(3),with exposed crystal faces of(101)and(400)for TiO_(2)andγ-Al_(2)O_(3),*** electronegativity difference of Ti4+and Al3+changes the charge distribution scheme around the interface,which provides abundant acid/base sites to boost the urea ***,for an optimal proportioning with nano TiO_(2)content at 10 wt.%,the hydrolysis efficiency can reach up to 35.2%at 100℃ in 2 h,increasing by~7.1%than that of the blank experiment.^(13)C NMR spectrum measurements provide the impossible intermediate species during urea *** calculations are performed to clarify the efficient H_(2)O decomposition at the interface of TiO_(2)@Al_(2)O_(3).The result offers a favorable technology for energy-efficiency urea hydrolysis.

关键词： scr Urea hydrolysis Catalytic Water dissociation Electronegativity

NO reduction using low-temperature scr assisted by a DBD method

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Plasma Science and Technology 2018年第1期20卷 8-15页

作者：刘杨海超张仁熙侯惠奇陈善平张瑞娜 Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP~3) Institute of Environmental Science Fudan University Shanghai Institute for Design & Research on Environmental Engineering

This paper discusses the removal of nitric oxide （NO） with low-temperature selective catalytic reduction driven by a dielectric barrier discharge with ammonia （NH3） as a reductant. We explored the effects of NH3, O2, temperature and water under different applied voltage on NO removal at atmospheric pressure. The results showed that when the gas concentration ration of NH3/NO was 0.23-0.67, the NO removal efficiency and the energy consumption was acceptable. The NO removal efficiency reached 84% under an applied voltage of 7 kV, 400 ppm NO and 90 ppm NH3 at a temperature of 150 ℃. Water vapor had a negative effect because NO formation reactions were strengthened and NH3 was oxidized directly rather than reduced NO molecules. The outlet gas components were observed via Fourier transform infrared spectroscopy for revealing the decomposition process and mechanism.

关键词： dielectric barrier discharge NO NH3 scr

Frequency Domain Fatigue Evaluation on scr Girth-Weld Based on Structural Stress

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China Ocean Engineering 2024年第2期38卷 255-270页

作者： ZHANG Long ZHAO Tian-feng College of Safety and Ocean Engineering China University of Petroleum(Beijing)Beijing 102249China

The Steel Catenary Riser(scr)is a vital component for transporting oil and gas from the seabed to the floating *** harsh environmental conditions and complex platform motion make the scr’s girth-weld prone to fatigue *** structural stress fatigue theory and Master S-N curve method provide accurate predictions for the fatigue damage on the welded joints,which demonstrate significant potential and compatibility in multi-axial and random fatigue ***,we propose a new frequency fatigue model subjected to welded joints of scr under multiaxial stress,which fully integrates the mesh-insensitive structural stress and frequency domain random process and transforms the conventional welding fatigue technique of scr into a spectrum analysis technique utilizing structural ***,a full-scale FE model of scr with welds is established to obtain the modal structural stress of the girth weld and the frequency response function(FRF)of modal coordinate,and a biaxial fatigue evaluation about the girth weld of the scr can be achieved by taking the effects of multi-load correlation and pipe-soil interaction into *** research results indicate that the frequency-domain fatigue results are aligned with the time-domain results,meeting the fatigue evaluation requirements of the scr.

关键词： scr girth weld random vibration self(cross)power spectrum structural stress method biaxial fatigue damage

Modeling and simulation of urea-water-solution droplet evaporation and thermolysis processes for scr systems

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Chinese Journal of Chemical Engineering 2016年第8期24卷 1065-1073页

作者： Xubo Gan Dongwei Yao Feng Wu Jiawei Dai Lai Wei Xingwen Li Institute of Power Machinery and Vehicular Engineering Zhejiang University

A reliable mathematical model of urea-water-solution(UWS) droplet evaporation and thermolysis is *** well known Abramzon–Sirignano evaporation model is corrected by introducing an adjustment coefficient considering the different evaporation behaviors of UWS droplet at different ambient temperatures. A semidetailed kinetic scheme of urea thermolysis is developed based on Ebrahimian's work. Sequentially, the evaporation characteristics, decomposition efficiency of a single UWS droplet and deposit formation are simulated. As a result, the relation of evaporation time, relative velocity, exhaust temperature and droplet initial diameter is presented. Synchronously, it indicates that temperature is the decisive factor for urea thermolysis. Different temperatures result in different deposit components, and deposit yield is significantly influenced by temperature and decomposition time. The current work can provide guidance for designing urea injection strategy of scr systems.

关键词： scr UWS evaporation Urea thermolysis Semi-detailed kinetic Simulation

Promotion effect of H2 pretreatment on CeO2 catalyst for NH3-scr reaction

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Journal of Rare Earths 2018年第7期36卷 708-714页

作者： Hongbing Lv Xiaoyu Hua Weiyang Xie Qing Hu Jianbo Wu Ruitang Guo Zhejiang Energy Group Hangzhou 310007China Zhejiang Energy Group R&D Hangzhou 311121China School of Energy Source and Mechanical Engineering Shanghai University of Electric PowerShanghai 200090China

In this study, the promotion effect of H2 pretreatment on the scr performance of CeO2 catalyst was investigated based on the characterization results of XRD, H2-TPR, Raman and in situ DRIFT *** crystallinity, higher reducibility and surface acidity can be found on CeO2-H catalyst. The results of DRIFT study reveal that the pretreatment of CeO2 catalyst with H2 can facilitate the adsorption of NH3 and NOx species, while the adsorbed NOx is basically inactive in the NH3-scr reaction. Moreover, the reaction mechanism of the NH3-scr reaction over CeO2 catalyst is not changed by H2 pretreatment,which is mainly under the control of Eley-Rideal（E-R） mechanism, The enhanced scr performance of CeO2-H catalyst is mainly due to the promoted NH3 adsorption and the subsequent facilitation of scr reaction through E-R pathway.

关键词： CeO2 catalyst scr H2 pretreatment In situ DRIFT Mechanism Rare earths

A bifunctional MnO_x@PTFE catalytic membrane for efficient low temperature NO_x-scr and dust removal

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Chinese Journal of Chemical Engineering 2020年第5期28卷 1260-1267页

作者： Shasha Feng Mengdi Zhou Feng Han Zhaoxiang Zhong Weihong Xing State Key Laboratory of Materials-Oriented Chemical Engineering National Engineering Research Center for Special Separation MembraneNanjing Tech UniversityNanjing 210009China Nanjing Industrial Technology Research Institute of Membrane Material Co.Ltd. Nanjing 211100China

Low-temperature selective catalytic reduction of NOx combined with dust removal technique due to its energy conservation characteristic has been attracted much attention for fume *** this work,the MnOx wrapped PTFE membrane with efficient dust removal and low-temperature NH3-scr has been prepared with a facile *** different crystal structures was uniformly grown around the PTFE fibrils through water *** flower-sphere-like MnOx@PTFE(O-MnOx@PTFE)and lamellar-interlaced ripple-like MnOx@PTFE(W-MnOx@PTFE)have large specific surface area which is favorable for enhancing catalytic ***,the uniformly wrapped W-MnOxaround the PTFE fibrils optimized the pore structure for ultrafine dust *** membrane can almost 100%reject particles that are smaller than 1.0μm with a low filtration ***,W-MnOx@PTFE with more surface chemisorbed oxygen has the best NO conversion efficiency of 100%at a comparatively low and wide activity temperature window of 160–210°C,which is far to the thermal limitation of the ***,this efficient and energy conserving membrane has a bright application prospects for tail gas treatment compared to the original treatment process.

关键词： MnO_x PTFE Catalytic membrane Low-temperature scr

ESD robustness studies on the double snapback characteristics of an LDMOS with an embedded scr

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Journal of Semiconductors 2011年第9期32卷 34-37页

作者：蒋苓利张波樊航乔明李肇基 State Key Laboratory of Electronic Thin Films and Integrated Devices University of Electronic Science and Technology

Criterion for the second snapback of an LDMOS with an embedded scr is given based on parasitic parameter *** to this criterion,three typical structures are compared by numerical simulation and structural parameters which influence the second snapback are also analyzed to optimize the ESD characteristics. Experimental data showed that,as the second snapback voltage decreased from 25.4 to 8.1 V,the discharge ability of the optimized structure increased from 0.57 to 3.1 A.

关键词： ESD LDMOS scr double snapback

Novel silicon-controlled rectifier(scr) for digital and high-voltage ESD power supply clamp

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Science China(Information Sciences) 2014年第2期57卷 291-296页

作者： ZHANG Peng WANG Yuan ZHANG Xing MA XiaoHua HAO Yue Key Laboratory of Wide Band-Gap Semiconductor Materials and Devices School of MicroelectronicsXidian University Key Laboratory of Microelectronic Devices and Circuits Institute of MicroelectronicsPeking University

Due to latch-up issue,the main problem of silicon-controlled rectifier(scr)for power supply clamps in on-chip ESD protection is its inherent low holding voltage,especially in high-voltage *** this paper,we proposed a MOS-inside scr(MIscr)showing nearly no snapback character and good ESD robustness,which is qualified for on-chip power clamp ESD *** stacked device achieves a series of triggering and holding voltage by altering the stacking number,which can also be used for the high voltage ESD power supply clamp applications.

关键词： electrostatic discharge(ESD) scr latch-up immunity holding voltage power supply clamp high voltage

A compact scr model using advanced BJT models and standard SPICE elements

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Science China(Information Sciences) 2016年第10期59卷 248-250页

作者： Jian CAO Jingya XU Yuan WANG Guangyi LU Xing ZHANG Key Laboratory of Microelectronic Devices and Circuits (Ministry of Education) Institute of MicroelectronicsPeking University School of Software & Microelectronics Peking University

Dear editor,The Silicon controlled rectifiers(scr)are widely used to protect integrated circuits(ICs)from electrostatic discharge(ESD)and electrical overstress(EOS)damage[1].An accurate scr model is highly desirable in on-chip ESD protection *** studies modeled scrs by aggregating conventional bipolar junction transistor(BJT)models and adding extra physical models that conventional BJT models fail to support[2,3].However the auxiliary models are mostly complicated

关键词： SPICE scr A compact scr model using advanced BJT models and standard SPICE elements BJT