Papers by Keyword: Selective Catalytic Reduction (SCR)

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Authors: Qiu Lin Zhang, Zhong Xian Song, Ping Ning, Jun Jie Gu
Abstract: A Ce-Zr-Mn-Ox (CZM) catalyst has been discovered for selective catalytic reduction of NOx with NH3 in the presence of O2. In this paper, The catalysts of CZM with 10~50 wt% MnO2 content and Ce-Zr-O2 (CZ) catalyst are prepared by hydrothermal synthesis method. The catalytic activity of CZM catalysts at different temperatures, different space velocities and different ratios of NH3/NO are studied. The results show that the catalyst of CZM with 40 wt% MnO2 content yields higher NO conversion at low temperature than others. This catalyst shows nearly 90% NOx conversion in a temperature range of 150°C~250 °C at a space velocity of 53000 h-1 .
Authors: Qian Wang, Ming Xing Zhou, Bao Yi Wang
Abstract: In order to fulfill future emission standards for middle and heavy-duty vehicles like state Ⅳ and Ⅴ, advanced measures on exhaust gas and engine functionality are required. Selective Catalytic Reduction (SCR) technology is the unique technology currently which can improve the emission and reduce fuel consumption simultaneously. Firstly the reductants and its chemical reactions, SCR system configurations and its working principle and urea dosing control strategy are introduced. Then tests are conducted on a diesel engine with SCR system at bench. The results of ESC cycle show that NOx emission is decreased by more than 67% with the open-loop control strategy. Additionally, the urea and fuel consumption and ammonia leakage have been compared and analyzed respectively, the experiment data indicates that the urea water solution consumption ratio is only 5.7% of fuel for this SCR system, while its average ammonia slip is below 5 ppm.
Authors: Guan Qiang Ruan, Zheng Dong Zhang, Qiang Wang
Abstract: Design principle of SCR control system for modern diesel engine is based on MAP which is obtained from experiments. The data of urea injection is obtained from MAP, the many experiments with different revolutions and loads are necessary. MAP from experiments is not accurate, cannot be used for all the range exactly in case of engine running conditions. Therefore, it is very difficult to design PID controller based on MAP. Moreover, the robust performance can not be achieved. To overcome these problems, the control scheme based on artificial neural network (ANN) is proposed. This controller has good robust performance and rapid adjustment. From experiments, the system using this controller can achieve good performance.
Authors: Chang Mao Hung
Abstract: The effect of treatment with different inorganic acids (HNO3, CH3COOH, and H3PO4) on the activity of CuO/γ-Al2O3 nanostructured catalysts selective catalytic reduction of NO by hydrocarbons (HC-SCR) using CH4 as a reducing agent in a tubular fixed-bed reactor (TFBR) at temperatures from 623-1023 K in the presence of oxygen was studied. A CuO/γ-Al2O3 nanostructured catalyst was prepared by incipient wetness impregnation approach of copper nitrate and γ-alumina support. The catalysts were characterized using AEM and XRD. The experimental results show that the support γ-alumina with a 6 N HNO3 solution at the calcinations temperature of 873 K obvious promoting effects on the higher activity due to greater acidity of the transforming NO reaction over a CuO/γ-Al2O3 nanostructured catalyst, because the acidic pretreatment provides the acidic sites for the catalyst surface and improved the dispersion of copper species and the reactivity over the catalyst reaction system with NO-CH4-O2. Further, cell cytotoxicity and the percentage cell survival was determined by using MTS assay on human fetal lung tissue cell (MRC-5). The experimental results show that the nanoscale CuO/γ-Al2O3 catalyst only minor cause cytotoxicity effect in cultured human cells.
Authors: Jian Yang, Qing Cai Liu, Mei Yang, Wen Chang Xi, Yan Hu
Abstract: TiO2 has been loaded on cordierite porous ceramic to prepare the SCR catalyst carrier by using both APCVD and sol-gel method. The physical properties, SEM and SEM-EDX of the TiO2-cordierite carrier have been analyzed. The results showed that TiO2 loaded by APCVD method were of graininess shape and accumulated evenly. The loading rate of TiO2 and the specific area of carrier sample were increased 114% and 21% respectively when using APCVD method. In the results of sol-gel method, the maximal difference of Ti content was 66.92%, while the result of APCVD method was 18.89%. It demonstrated that TiO2 was uniformly attached with the cordierite ceramic by using APCVD method. That would ensure the active ingredients well loaded on the TiO2-cordierite carrier in the next process.
Authors: Wen Huan Wang, Wei Guo Pan, Guo Xin Hu
Abstract: Life cycle analysis combined with technical economic evaluation method in the paper to control the cost of denitration. A simple model for denitration cost is developed. The influence of different flue gas concentration of NOx to the cost of unit denitration is analysed by life cycle analysis, includes construction, operation and decommissioning, which based on 600 MW coal-fired units. Preliminary calculations reveal that comparing with directly using the denitration technology of selective catalytic reduction (SCR), after using Air staged Low NOx Combustion Technology reduced NOx below 400mg/m3, using SCR denitration further decreased the concentration of NOx in flue gas to 100mg/m3 can save more than 44% of the general denitration cost. This can improve effectively the environmental protection and economy of the coal-fired unit.
Authors: Rong Liu, Zhi Qin Yang, Hao Guan
Abstract: A catalyst, 8%Fe-10%MnOx-CeO2/ZrO2, was prepared and applied for selective catalytic reduction of NO with NH3 at low temperature. The effects of SO2 and H2O on the catalyst were studied. The results showed that in the absence of SO2 and H2O, the catalyst 8%Fe-10%MnOx-CeO2/ZrO2 has good activity and stability. The presence of SO2 and H2O make the catalyst deactivate, and the activity can be recovered mostly by heating at 400°C. Properties of the catalyst on different reaction stages were characterized by FT-IR to study the inactivation mechanism of the catalyst. The results showed that the catalyst deactivation is due to the deposition of ammonium sulfate on the catalyst and the sulphation of the metal oxides of the catalyst.
Authors: Ning Zhao, Si Wei Pan, Zheng Le Wei
Abstract: With the wide application of SCR technology, the deactivation of SCR catalyst has caught attention in the coal-fired power plants. The activities of fresh and used SCR catalysts were compared and the deactivation reasons were analyzed by using scanning electron microscope (SEM), BET, X-ray diffraction (XRD), and X-ray fluorescence (XRF). The results showed that the specific surface area of the used catalyst decreased significantly, caused by the pore blockage of fly ash or sulfates on the surface of the used catalyst. The activity of the used catalyst decreased seriously, and the relative activity of the field sample had declined to 0.60. Moreover, according to the results of X-ray fluorescence, alkali poisoning was one of the main reasons for the decline in the activity of the catalyst.
Authors: Wen Chang Xi, Qing Cai Liu, De Liang Niu, Jian Yang, Qiang Yang, Yuan Peng, Xiao Yan Zhou, He Kun Zhang, Hong Yan
Abstract: The V2O5-WO3/TiO2 honeycomb catalysts with cordierite modified were prepared by solid-liquid mixing method. Its thermal stability, crystal structure, abrasion resistance and activity were studied by XRD, abrasion equipment and simulated flue gas analyzer,respectively. The results indicated that V2O5-WO3/Cordierite-TiO2 honeycomb catalyst possessed a better thermal stability, mechanical property and activity at the higher temperature comparing to commercial catalyst. There was no rutile phase present after the catalysts were calcined at 700°C, and the vanadia and tungsten trioxide phases could be apparently visible on TiO2. Key word:V2O5-WO3/ TiO2; Cordierite; flue gas denitrification; NOx; selective catalytic reduction (SCR)
Authors: Wei Li, Hong Yu Lu, Hong Song Guo
Abstract: The effects of fuel quality and pollution control devices on SOF and PAHs emissions in particle matter (PM) for China V heavy-duty (HD) diesel engine fueled with China III, China IV and China V diesel were studied by using soxhlet extraction technique and Gas Chromatography-Mass Spectroscopy (GC-MS) technique. Two engines used were equipped with Diesel Oxidation Convert (DOC)+Diesel Particulate Filter (DPF) and Select Catalytic Reduction (SCR) individually. It is found that the SOF mass fraction in PM rises remarkably and total PAHs concentration declines obviously with the improvement of diesel fuel from China III to China V. However, the 16 components of PAHs distribute similarly for three quality of diesel, the concentrationes of Flu、PA、Ant、FL、Pyr、BaA、CHR reduce obviously, especially Pyr decrease by 95.8%. Moreover, the pollution control device has important effects on SOF and PAHs emissions.
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