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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    

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    

Effects of support acidity on the reaction mechanisms of selective catalytic reduction of NO by CH

Shicheng XU, Junhua LI, Dong YANG, Jiming HAO

《环境科学与工程前沿(英文)》 2009年 第3卷 第2期   页码 186-193 doi: 10.1007/s11783-009-0016-5

摘要: The reaction mechanisms of selective catalytic reduction (SCR) of nitric oxide (NO) by methane (CH ) over solid superacid-based catalysts were proposed and testified by DRIFTS studies on transient reaction as well as by kinetic models. Catalysts derived from different supports would lead to different reaction pathways, and the acidity of solid superacid played an important role in determining the reaction mechanisms and the catalytic activities. Higher ratios of Br?nsted acid sites to Lewis acid sites would lead to stronger oxidation of methane and then could facilitate the step of methane activation. Strong Br?nsted acid sites would not necessarily lead to better catalytic performance, however, since the active surface NO species and the corresponding reaction routes were determined by the overall acidity strength of the support. The reaction routes where NO moiety was engaged as an important intermediate involved moderate oxidation of methane, the rate of which could determine the overall activity. The reaction involving NO moiety was likely to be determined by the step of reduction of NO. Therefore, to enhance the SCR activity of solid superacid catalysts, reactions between appropriate couples of active NO species and activated hydrocarbon intermediates should be realized by modification of the support acidity.

关键词: selective catalytic reduction (SCR)     nitric oxide (NO)     methane     support acidity     Br?nsted acid sites     NOy species    

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    

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    

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    

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)    

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    

Effect of K and Ca on catalytic activity of Mn-CeO

Boxiong SHEN, Lidan DENG, Jianhong CHEN

《环境科学与工程前沿(英文)》 2013年 第7卷 第4期   页码 512-517 doi: 10.1007/s11783-013-0519-y

摘要: Mn-CeO /Ti-pillared clay (PILC) is an attractive catalyst for selective catalytic reduction of NO at low temperature because of its low cost. The poisoning of K and Ca on the catalyst of Mn-CeO /Ti-PILC is an important problem because K and Ca are always in presence in flue gas. To investigate the effect of K and Ca on the physicochemical characters of the catalysts, the techniques of NH -temperature programmed desorption (TPD), H -temperature programmed reduction (TPR), and X-ray photoelectron spectroscopy (XPS) were used to analyze the fresh and deactivated catalysts of Mn-CeO /Ti-PILC. (Ca)Mn-CeO /Ti-PILC and (K)Mn-CeO /Ti-PILC are denoted for the dopes of the catalyst of Mn-CeO /Ti-PILC with Ca and K, respectively. The activities of Mn-CeO /Ti-PILC, (Ca)Mn-CeO /Ti-PILC and (K)Mn-CeO /Ti-PILC for NH -selective catalytic reduction (SCR) reaction at low temperature were investigated. The results showed that with the dopes of K and Ca on the catalysts, the SCR activities of the catalysts decreased greatly, and K exhibited more poisoning effect than Ca. With the dopes of K and Ca, the acidity, the redox property and chemisorbed oxygen on the surfaces of the catalysts were decreased, which resulted in a decreasing in SCR activity.

关键词: Mn-CeOx/Ti-pillared clay (PILC)     low-temperature selective catalytic reduction (SCR)     K and Ca poisoning effect    

dispersion behavior of Co3O4 on HZSM-5 support: designing applicable catalysts for selectivecatalytic reduction of nitrogen oxides by ammonia

《化学科学与工程前沿(英文)》 2023年 第17卷 第11期   页码 1741-1754 doi: 10.1007/s11705-023-2332-x

摘要: Based on monolayer dispersion theory, Co3O4/ZSM-5 catalysts with different loadings have been prepared for selective catalytic reduction of nitrogen oxides by ammonia. Co3O4 can spontaneously disperse on HZSM-5 support with a monolayer dispersion threshold of 0.061 mmol 100 m–2, equaling to a weight percentage around 4.5%. It has been revealed that the quantities of surface active oxygen (O2) and acid sites are crucial for the reaction, which can adsorb and activate NOx and NH3 reactants effectively. Below the monolayer dispersion threshold, Co3O4 is finely dispersed as sub-monolayers or monolayers and in an amorphous state, which is favorable to generate the two kinds of active sites, hence promoting the performance of ammonia selective catalytic reduction of nitrogen oxide. However, the formation of crystalline Co3O4 above the capacity is harmful to the reaction performance. 4% Co3O4/ZSM-5, the catalyst close to the monolayer dispersion capacity, possesses the most abundant active O2 species and acidic sites, thereby demonstrating the best reaction performance in all the samples. It is proposed the optimal Co3O4/ZSM-5 catalyst can be prepared by loading the capacity amount of Co3O4 onto HZSM-5 support.

关键词: Co3O4/ZSM-5     NOx-SCR by NH3     monolayer dispersion threshold effect     surface acid sites     surface active O2 anions    

Insight into the promotion mechanism of activated carbon on the monolithic honeycomb red mud catalyst for selectivecatalytic reduction of NO

《环境科学与工程前沿(英文)》 2021年 第15卷 第5期 doi: 10.1007/s11783-020-1337-7

摘要:

• Activated carbon was proposed to be an efficient accelerant for molded red mud catalyst.

关键词: NOx     Selective catalytic reduction     Iron-based catalyst     Red mud     Monolithic catalyst     Activated carbon    

Effect of different acid anions on highly efficient Ce-based catalysts for selective catalytic reduction

《化学科学与工程前沿(英文)》 2023年 第17卷 第10期   页码 1399-1411 doi: 10.1007/s11705-023-2345-5

摘要: Three kinds of Ce-based catalysts (CePO4, CeVO4, Ce2(SO4)3) were synthesized and used for the selective catalytic reduction (SCR) of NO by NH3. NH3-SCR performances were conducted in the temperature range of 80 to 400 °C. The catalytic efficiencies of the three catalysts are as follow: CePO4 > CeVO4 > Ce2(SO4)3, which is in agreement with their abilities of NH3 adsorption capacities. The highest NO conversion rate of CePO4 could reach about 95%, and the catalyst had more than 90% NO conversion rate between 260 and 320 °C. The effect of PO43–, VO43– and SO42– on NH3-SCR performances of Ce-based catalysts was systematically investigated by the X-ray photoelectron spectroscopy analysis, NH3 temperature programmed desorption, H2 temperature programmed reduction and field emission scanning electron microscopy tests. The key factors that can enhance the SCR are the existence of Ce4+, large NH3 adsorption capacity, high and early H2 consumptions, and suitable microstructures for gas adsorption. Finally, CePO4 and CeVO4 catalysts also exhibited relatively strong tolerance of SO2, and the upward trend about 8% was detected due to the sulfation enhancement by SO2 for Ce2(SO4)3.

关键词: CePO4     CeVO4     Ce2(SO4)3     selective catalytic reduction     NO removal    

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    

Metal-organic framework loaded manganese oxides as efficient catalysts for low-temperature selectivecatalytic reduction of NO with NH

Minhua Zhang, Baojuan Huang, Haoxi Jiang, Yifei Chen

《化学科学与工程前沿(英文)》 2017年 第11卷 第4期   页码 594-602 doi: 10.1007/s11705-017-1668-5

摘要: A mild deposition method was used to fabricate Mn-based catalysts on a UiO-66 carrier for the selective catalytic reduction of NO by NH (NH -SCR). The catalyst with 8.5 wt-% MnO loading had the highest catalytic activity for NH -SCR with a wide temperature window (100–290 °C) for 90% NO conversion. Characterization of the prepared MnO /UiO-66 catalysts showed that the catalysts had the crystal structure and porosity of the UiO-66 carrier and that the manganese particles were well-distributed on the surface of the catalyst. X-ray photoelectron spectroscopy analysis showed that there are strong interactions between the MnO and the Zr oxide secondary building units of the UiO-66 which has a positive effect on the catalytic activity. The 8.5 wt-% MnO catalyst maintained excellent activity during a 24-h stability test and exhibited good resistance to SO poisoning.

关键词: metal-organic framework     selective catalytic reduction     manganese oxides     deNOx     SO2 resistance    

Low-temperature selective catalytic reduction of NO with NH based on MnO-CeO/ACFN

SHEN Boxiong, LIU Ting, SHI Zhanliang, SHI Jianwei, YANG Tingting, ZHAO Ning

《化学科学与工程前沿(英文)》 2008年 第2卷 第3期   页码 325-329 doi: 10.1007/s11705-008-0053-9

摘要: MnO-CeO/ACFN were prepared by the impregnation method and used as catalyst for selective catalytic reduction of NO with NH at 80°C–150°C. The catalyst was characterized by N-BET, scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). The fraction of the mesopore and the oxygen functional groups on the surface of activated carbon fiber (ACF) increased after the treatment with nitric acid, which was favorable to improve the catalytic activities of MnO-CeO/ACFN. The experimental results show that the conversion of NO is nearly 100% in the range 100°C–150°C under the optimal preparation conditions of MnO-CeO/ACFN. In addition, the effects of a series of performance parameters, including initial NH concentration, NO concentration and O concentration, on the conversion of NO were studied.

关键词: preparation     conversion     favorable     selective catalytic     MnO-CeO/ACFN    

标题 作者 时间 类型 操作

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

Chen ZHANG, Guoliang AN, Liwei WANG, Shaofei WU

期刊论文

Selective catalytic reduction of NO

Pavlo I. Kyriienko

期刊论文

Effects of support acidity on the reaction mechanisms of selective catalytic reduction of NO by CH

Shicheng XU, Junhua LI, Dong YANG, Jiming HAO

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

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

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

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

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

YiangChen CHOU, Young KU

期刊论文

Effect of K and Ca on catalytic activity of Mn-CeO

Boxiong SHEN, Lidan DENG, Jianhong CHEN

期刊论文

dispersion behavior of Co3O4 on HZSM-5 support: designing applicable catalysts for selectivecatalytic reduction of nitrogen oxides by ammonia

期刊论文

Insight into the promotion mechanism of activated carbon on the monolithic honeycomb red mud catalyst for selectivecatalytic reduction of NO

期刊论文

Effect of different acid anions on highly efficient Ce-based catalysts for selective catalytic reduction

期刊论文

Characterization and performance of V

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

期刊论文

Metal-organic framework loaded manganese oxides as efficient catalysts for low-temperature selectivecatalytic reduction of NO with NH

Minhua Zhang, Baojuan Huang, Haoxi Jiang, Yifei Chen

期刊论文

Low-temperature selective catalytic reduction of NO with NH based on MnO-CeO/ACFN

SHEN Boxiong, LIU Ting, SHI Zhanliang, SHI Jianwei, YANG Tingting, ZHAO Ning

期刊论文