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Selective reduction of NO by photo-SCR with ammonia in an annular fixed-film photoreactor

YiangChen CHOU, Young KU

《环境科学与工程前沿(英文)》 2012年 第6卷 第2期   页码 149-155 doi: 10.1007/s11783-010-0296-9

摘要: Gaseous NO was photocatalytically reduced at room temperature by photo-assisted selective catalytic reduction (photo-SCR) with ammonia over TiO in this study. NO reduction efficiency and N selectivity were determined from gases composition at the outlet stream of photoreactor. Effect of operating conditions, e.g. light intensity and inlet concentrations of ammonia and oxygen, on the NO reduction efficiency and N selectivity were discussed to determine the feasible operating condition for photocatalytic reduction of NO. Experimental results showed that selective catalytic reduction of NO with ammonia over TiO in the presence of oxygen was a spontaneous reaction in dark. The photoirradiation on the TiO surface caused remarkable photocatalytic reduction of NO to form N , NO , and N O under 254 nm UV illuminations, while almost 90% of N selectivity was achieved in this study. The ammonia and oxygen molecules played the roles of reductant and oxidant for NO reduction and active sites regeneration, respectively. The reduction of NO was found to be increased with the increase of inlet ammonia and oxygen concentrations until specific concentrations because of the limited active sites on the surface of TiO . The kinetic model proposed in this study can be used to reasonably describe the reaction mechanism of photo-SCR.

关键词: photo-SCR     photocatalysis     NO reduction     Eley-Rideal model    

CeO doping boosted low-temperature NH-SCR activity of FeTiO catalyst: A microstructure analysis and reaction

《环境科学与工程前沿(英文)》 2022年 第16卷 第5期 doi: 10.1007/s11783-022-1539-2

摘要:

• CeO2 doping significantly improved low-temperature NH3-SCR activity on FeTiOx.

关键词: NH3-SCR     CeO2 doping     Low-temperature NOx removal     Improved redox property     In situ XAFS analysis    

Precise regulation of acid pretreatment for red mud SCR catalyst: Targeting on optimizing the acidity

《环境科学与工程前沿(英文)》 2022年 第16卷 第7期 doi: 10.1007/s11783-021-1447-x

摘要:

• The optimum SCR activity was realized by tuning the acid pretreatment.

关键词: Air pollution control     Nitrogen oxides     Selective catalytic reduction     Red mud     Solid waste utilization    

Numerical simulation and experimental verification of chemical reactions for SCR DeNO

Qiang ZHANG, Yonglin FAN, Wenyan LI

《化学科学与工程前沿(英文)》 2010年 第4卷 第4期   页码 523-528 doi: 10.1007/s11705-010-0520-y

摘要: Selective catalytic reduction (SCR) is a major commercial technology for NO removal in power plants. There are a lot of complex chemical reactions in SCR reactors, and it is of great significance to understand the internal process of chemical reactions for SCR DeNO and study the impact of various factors on NO removal efficiency. In this paper, the impact of reaction temperature, ammonia-nitrogen molar ratio and resident time in the catalyst bed layer on NO removal efficiency were studied by simulation of chemical reactions. Then calculated results were compared with catalyst activity test data in a power plant, which proved that the simulated results were accurate. As a result, the reaction conditions were optimized in order to get the best removal efficiency of NO, so that we can provide a reference for optimal running of SCR in power plants.

关键词: SCR     NOx     removal efficiency     chemical reactions     simulation    

Design guidelines for urea hydrolysers for ammonia demand of the SCR DENOX project in coal-fired power

Peng ZHENG, Xuan YAO, Wei ZHENG

《能源前沿(英文)》 2013年 第7卷 第1期   页码 127-132 doi: 10.1007/s11708-012-0225-7

摘要: Ammonia is highly volatile and will present substantial environmental and operation hazards when leaking into the air. However, ammonia is the most common reactant in the DENOX project to eliminate NO in the flue gas. The storage and transportation of liquid ammonia has always been a dilemma of the power plant. Urea is a perfect substitute source for ammonia in the plant. Urea hydrolysis technology can easily convert urea into ammonia with low expense. Presently, there is still no self-depended mature urea hydrolysis technology for the DENOX project in China; therefore, this paper proposes several guidelines to design the urea hydrolyser by theoretical analysis. Based on theoretical analysis, a simulation model is built to simulate the chemical reaction in the urea hydrolyser and is validated by the operational data of the commercial hydrolyser revealed in the literature. This paper endeavors to propose suggestions and guidelines to develop domestically urea hydrolysers in China.

关键词: urea     hydrolyser     ammonia     selective catalytic reduction (SCR)    

NiBO (B = Mn or Co) catalysts for NH-SCR of NO at low-temperature in microwave field

《环境科学与工程前沿(英文)》 2023年 第17卷 第8期 doi: 10.1007/s11783-023-1696-y

摘要:

● Microwave-assisted catalytic NH3-SCR reaction over spinel oxides is carried out.

关键词: Microwave field     Spinel oxides     NOx     Selective catalytic reduction    

Denitrification performance and sulfur resistance mechanism of Sm–Mn catalyst for low temperature NH-SCR

《化学科学与工程前沿(英文)》 2023年 第17卷 第5期   页码 617-633 doi: 10.1007/s11705-022-2258-8

摘要: MnOx and Sm–Mn catalysts were prepared with the coprecipitation method, and they showed excellent activities and sulfur resistances for the selective catalytic reduction of NOx by NH3 between 50 and 300 °C in the presence of excess oxygen. 0.10Sm–Mn catalyst indicated better catalytic activity and sulfur resistance. Additionally, the Sm doping led to multi-aspect impacts on the phases, morphology structures, gas adsorption, reactions process, and specific surface areas. Therefore, it significantly enhances the NO conversion, N2 selectivity, and sulfur resistance. Based on various experimental characterization results, the reaction mechanism of catalysts and the effect of SO2 on the reaction process about the catalysts were extensively explored. For 0.10Sm–Mn catalyst, manganese sulfate and sulfur ammonium cannot be generated broadly under the influence of SO2 and the amount of surface adsorbed oxygen. The Bronsted acid sites strengthen significantly due to the addition of SO2, enhancing the sulfur resistance of the 0.10Sm–Mn catalyst.

关键词: MnOx     Sm–Mn     catalyst     NH3-SCR     sulfur resistance    

Chemical poison and regeneration of SCR catalysts for NOx

Junhua LI,Yue PENG,Huazhen CHANG,Xiang LI,John C. CRITTENDEN,Jiming HAO

《环境科学与工程前沿(英文)》 2016年 第10卷 第3期   页码 413-427 doi: 10.1007/s11783-016-0832-3

摘要: Selective catalytic reduction (SCR) of NO with NH is an effective technique to remove NO from stationary sources, such as coal-fired power plant and industrial boilers. Some of elements in the fly ash deactivate the catalyst due to strong chemisorptions on the active sites. The poisons may act by simply blocking active sites or alter the adsorption behaviors of reactants and products by an electronic interaction. This review is mainly focused on the chemical poisoning on V O -based catalysts, environmental-benign catalysts and low temperature catalysts. Several common poisons including alkali/alkaline earth metals, SO and heavy metals etc. are referred and their poisoning mechanisms on catalysts are discussed. The regeneration methods of poisoned catalysts and the development of poison-resistance catalysts are also compared and analyzed. Finally, future research directions in developing poisoning resistance catalysts and facile efficient regeneration methods for SCR catalysts are proposed.

关键词: flue gas     DeNOx     SCR catalyst     poison and regeneration    

Selective catalytic reduction of NO

Pavlo I. Kyriienko

《化学科学与工程前沿(英文)》 2020年 第14卷 第4期   页码 471-491 doi: 10.1007/s11705-019-1847-7

摘要: Research results regarding selective catalytic reduction (SCR) of NO with ethanol and other C oxygenates as reductants over silver-alumina catalysts are summarized. The aspects of the process mechanism, nature of active sites, role of alumina and silver (especially in the formation of bifunctional active sites), effects of reductants and reaction conditions are discussed. It has been determined that key stages of the process include formation of reactive enolic species, their interaction with NO and formation of nitroorganic compounds which transform to NCO species and further to N . The results obtained over various silver-alumina catalysts demonstrate the perspectives of their application for reducing the level of nitrogen oxides in engine emissions, including in the presence of water vapor and sulfur oxides. Ways to improve the catalysts for the SCR of NO with C oxygenates are outlined.

关键词: SCR     nitrogen oxides     silver-alumina catalyst     silver species     ethanol     oxygenates    

Development of highly active coated monolith SCR catalyst with strong abrasion resistance for low-temperature

Lina GAN,Shan LEI,Jian YU,Hongtao MA,Yo YAMAMOTO,Yoshizo SUZUKI,Guangwen XU,Zhanguo ZHANG

《环境科学与工程前沿(英文)》 2015年 第9卷 第6期   页码 979-987 doi: 10.1007/s11783-015-0824-8

摘要: Monolith SCR catalysts coated with V O -WO /TiO were prepared by varying binder and coating thickness. Comparing with a monolith extruded with 100% V O -WO /TiO powder, a coated monolith with a catalyst-coating layer of 260 μm in thickness exhibited the similar initial NO reduction activity at 250°C. After 4 h abrasion (attrition) in an air stream containing 300 g·m fine sands (50–100 μm) at a superficial gas velocity of 10 m·s , the catalyst still has the activity as a 100% molded monolith does in a 24-h activity test and it retains about 92% of its initial activity at 250°C. Estimation of the equivalent durable hours at a fly ash concentration of 1.0 g·m in flue gas and a gas velocity of 5 m·s demonstrated that this coated monolith catalyst is capable of resisting abrasion for 13 months without losing more than 8% of its initial activity. The result suggests the great potential of the coated monolith for application to de-NO of flue gases with low fly ash concentrations from, such as glass and ceramics manufacturing processes.

关键词: coated monolith     low-temperature denitration     abrasion resistance     attrition    

NO oxidation over Co-La catalysts and NO

Tiejun Zhang,Jian Li,Hong He,Qianqian Song,Quanming Liang

《环境科学与工程前沿(英文)》 2017年 第11卷 第2期 doi: 10.1007/s11783-017-0906-x

摘要: The Co-La catalyst (pH= 1) exhibited maximum NO conversion of 43% at 180°C. Acid modified catalyst enhanced the resistance to SO . The formed sulfates may block the pore structure of the catalyst. The NO conversion of compact SCR was 91% at 180°C at the highest space velocity. A series of Co-La catalysts were prepared using the wet impregnation method and the synthesis of catalysts were modified by controlling pH with the addition of ammonium hydroxide or oxalic solution. All the catalysts were systematically investigated for NO oxidation and SO resistance in a fixed bed reactor and were characterized by Brunanuer–Emmett–Teller (BET) method, Fourier Transform infrared spectroscopy (FTIR), X–ray diffraction (XRD), Thermogravimetric (TG) and Ion Chromatography (IC). Among the catalysts, the one synthesized at pH= 1 exhibited the maximum NO conversion of 43% at 180°C. The activity of the catalyst was significantly suppressed by the existence of SO (300 ppm) at 220°C. Deactivation may have been associated with the generation of cobalt sulfate, and the SO adsorption quantity of the catalyst might also have effected sulfur resistance. In the case of the compact selective catalytic reduction (SCR), the activity increased from 74% to 91% at the highest gas hourly space velocity (GHSV) of 300000 h when the NO catalyst maintained the highest activity, in excess of 50% more than that of the standard SCR.

关键词: NO catalytic oxidation     pH effect     Low temperature     Sulfur dioxide     High space velocity     SCR    

Effects of SO

Quanming Liang, Jian Li, Hong He, Wenjun Liang, Tiejun Zhang, Xing Fan

《环境科学与工程前沿(英文)》 2017年 第11卷 第4期 doi: 10.1007/s11783-017-0926-6

摘要: The CeO -V O -WO /TiO (CeO -VWT) catalysts were prepared by one-step and two-step impregnation methods. The effects of different loading of CeO and different preparation methods on De-NO activity of catalysts had been investigated. CeO helped to improve the De-NO activity and sulfur resistance. The optimal loading of CeO was 3% with the De-NO efficiency reached 89.9% at 140°C. The results showed that the De-NO activity of 3% CeO -VWT catalysts by one-step method was the same as two-step method basically and reached the level of industrial applications, the N selectivity of catalysts was more than 99.2% between 110°C and 320°C. In addition, CeO promoted the oxidation of NO to NO , which adsorbed on the Lewis acid site (V ═O) to form V ═NO and inspired the fast SCR reaction. Not only the thermal stability but also the De-NO activity of catalysts decreased with excess CeO competed with V O . Characterizations of catalysts were carried out by XRF, BET, XRD, TG and FT-IR. BET showed that the specific surface area of catalysts decreased with the loading of CeO increased, the active components content and specific surface area of catalysts decreased slightly after entering SO . Ammonium sulfate species were formed in poisoned catalyst which had been investigated by XRF, BET, TG and FT-IR. The largest loss rate of weight fraction was 0.024%·°C at 380°C–390°C, which was in accordance with the decomposition temperature of NH HSO and (NH ) SO .

关键词: Low temperature SCR     De-NOx activity     Sulfur resistance     Ammonium sulfate    

Characterization and performance of V

Caiting LI, Qun LI, Pei LU, Huafei CUI, Guangming ZENG

《环境科学与工程前沿(英文)》 2012年 第6卷 第2期   页码 156-161 doi: 10.1007/s11783-010-0295-x

摘要: A series of CeO supported V O catalysts with various loadings were prepared with different calcination temperatures by the incipient impregnation. The catalysts were evaluated for low temperature selective catalytic reduction (SCR) of NO with ammonia (NH ). The effects of O and SO on catalytic activity were also studied. The catalysts were characterized by specific surface areas (S ) and X–ray diffraction (XRD) methods. The experimental results showed that NO conversion changed significantly with the different V O loading and calcination temperature. With the V O loading increasing from 0 to 10 wt%, NO conversion increased significantly, but decreased at higher loading. The optimum calcination temperature was 400°C. The best catalyst yielded above 80% NO conversion in the reaction temperature range of 160°C–300°C. The formation of CeVO on the surface of catalysts caused the decrease of redox ability.

关键词: V2O5/CeO2 catalysts     NH3-SCR (selective catalytic reduction)     the incipient impregnation     low temperatures    

Multi-stage ammonia production for sorption selective catalytic reduction of NO

Chen ZHANG, Guoliang AN, Liwei WANG, Shaofei WU

《能源前沿(英文)》 2022年 第16卷 第5期   页码 840-851 doi: 10.1007/s11708-021-0797-1

摘要: Sorption selective catalytic reduction of nitrogen oxides (NOx) (sorption-SCR) has ever been proposed for replacing commercial urea selective catalytic reduction of NOx (urea-SCR), while only the single-stage sorption cycle is hitherto adopted for sorption-SCR. Herein, various multi-stage ammonia production cycles is built to solve the problem of relative high starting temperature with ammonia transfer (AT) unit and help detect the remaining ammonia in ammonia storage and delivery system (ASDS) with ammonia warning (AW) unit. Except for the single-stage ammonia production cycle with MnCl2, other sorption-SCR strategies all present overwhelming advantages over urea-SCR considering the much higher NOx conversion driven by the heat source lower than 100°C and better matching characteristics with low-temperature catalysts. Furthermore, the required mass of sorbent for each type of sorption-SCR is less than half of the mass of AdBlue for urea-SCR. Therefore, the multifunctional multi-stage sorption-SCR can realize compact and renewable ammonia storage and delivery with low thermal energy consumption and high NOx conversion, which brings a bright potential for efficient commercial de-NOx technology.

关键词: selective catalytic reduction (SCR)     nitrogen oxides (NOx)     ammonia     composite sorbent     chemisorption    

Design and operational considerations for selective catalytic reduction technologies at coal-fired boilers

Jeremy J. SCHREIFELS, Shuxiao WANG, Jiming HAO

《能源前沿(英文)》 2012年 第6卷 第1期   页码 98-105 doi: 10.1007/s11708-012-0171-4

摘要: By the end of 2010, China had approximately 650 GW of coal-fired electric generating capacity producing almost 75% of the country’s total electricity generation. As a result of the heavy reliance on coal for electricity generation, emissions of air pollutants, such as nitrogen oxides (NO ), are increasing. To address these growing emissions, the Ministry of Environmental Protection (MEP) has introduced new NO emission control policies to encourage the installation of selective catalytic reduction (SCR) technologies on a large number of coal-fired electric power plants. There is, however, limited experience with SCR in China. It is therefore useful to explore the lessons from the use of SCR technologies in other countries. This paper provides an overview of SCR technology performance at coal-fired electric power plants demonstrating emission removal rates between 65% and 92%. It also reviews the design and operational challenges that, if not addressed, can reduce the reliability, performance, and cost-effectiveness of SCR technologies. These challenges include heterogeneous flue gas conditions, catalyst degradation, ammonia slip, sulfur trioxide (SO ) formation, and fouling and corrosion of plant equipment. As China and the rest of the world work to reduce greenhouse gas emissions, carbon dioxide (CO ) emissions from parasitic load and urea-to-ammonia conversion may also become more important. If these challenges are properly addressed, SCR can reliably and effectively remove up to 90% of NO emissions at coal-fired power plants.

关键词: nitrogen oxides (NOx)     coal     selective catalytic reduction (SCR)     air pollution control    

标题 作者 时间 类型 操作

Selective reduction of NO by photo-SCR with ammonia in an annular fixed-film photoreactor

YiangChen CHOU, Young KU

期刊论文

CeO doping boosted low-temperature NH-SCR activity of FeTiO catalyst: A microstructure analysis and reaction

期刊论文

Precise regulation of acid pretreatment for red mud SCR catalyst: Targeting on optimizing the acidity

期刊论文

Numerical simulation and experimental verification of chemical reactions for SCR DeNO

Qiang ZHANG, Yonglin FAN, Wenyan LI

期刊论文

Design guidelines for urea hydrolysers for ammonia demand of the SCR DENOX project in coal-fired power

Peng ZHENG, Xuan YAO, Wei ZHENG

期刊论文

NiBO (B = Mn or Co) catalysts for NH-SCR of NO at low-temperature in microwave field

期刊论文

Denitrification performance and sulfur resistance mechanism of Sm–Mn catalyst for low temperature NH-SCR

期刊论文

Chemical poison and regeneration of SCR catalysts for NOx

Junhua LI,Yue PENG,Huazhen CHANG,Xiang LI,John C. CRITTENDEN,Jiming HAO

期刊论文

Selective catalytic reduction of NO

Pavlo I. Kyriienko

期刊论文

Development of highly active coated monolith SCR catalyst with strong abrasion resistance for low-temperature

Lina GAN,Shan LEI,Jian YU,Hongtao MA,Yo YAMAMOTO,Yoshizo SUZUKI,Guangwen XU,Zhanguo ZHANG

期刊论文

NO oxidation over Co-La catalysts and NO

Tiejun Zhang,Jian Li,Hong He,Qianqian Song,Quanming Liang

期刊论文

Effects of SO

Quanming Liang, Jian Li, Hong He, Wenjun Liang, Tiejun Zhang, Xing Fan

期刊论文

Characterization and performance of V

Caiting LI, Qun LI, Pei LU, Huafei CUI, Guangming ZENG

期刊论文

Multi-stage ammonia production for sorption selective catalytic reduction of NO

Chen ZHANG, Guoliang AN, Liwei WANG, Shaofei WU

期刊论文

Design and operational considerations for selective catalytic reduction technologies at coal-fired boilers

Jeremy J. SCHREIFELS, Shuxiao WANG, Jiming HAO

期刊论文