CHEMOSPHERE
·
2020
·
IF 5.778
Jiuhu Zhao,Gaige Zhang,Jiansheng He,Zhengzhong Wen,Zhi Li,Tingkun Gu,Ran Ding,Yongji Zhu,Rongshu Zhu
In/H-Beta catalyst was prepared by optimizing the support, concentration of ion exchange liquid and calcination temperature to investigate the effects of synthesis conditions on catalytic activity of selective catalytic reduction of NO x with CH 4 . The results showed that the In/H-Beta catalyst exhibited the superior activity when concentration of exchange liquid was 0.033 M and calcination temperature was 500 °C, the NO x removal ratio could reach 97.6%. In addition, reaction conditions could affect the catalytic performance. When O 2 concentration was 10%, CH 4 :NO ratio was no less than one, space velocity was lower than 23600 h −1 and NO initial concentration was no more than 700 ppm, In/H-Beta could exhibit superior catalytic activity. Moreover, the catalytic performances of In/H-Beta catalysts were discussed after enduring H 2 O or/and SO 2 . This novel strategy could open the door for selective catalytic reduction of NO x with CH 4 .
研究领域:
环境科学
·
催化化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CATALYSIS TODAY
·
2018
·
IF 4.667
Xianghui Li,Yingnan Zhao,Huawang Zhao,Mengke Liu,Yuhan Ma,Xin Yong,Hong Chen,Yongdan Li
Two kinds of Cu-SAPO-34 catalysts, prepared with a one-pot technique using Cu- tetraethylenepentamine as co-template and an ion-exchange method, were hydrothermally treated at 750 °C for at least 16 h. The migration of Cu species during hydrothermal treatment and the corresponding effect on the selective catalytic reduction (SCR) of NO x were examined and characterized. A certain amount of CuO exists outside and inner the crystallites in the as prepared ion-exchanged sample, whereas copper is mainly atomically dispersed in the one-pot sample existing as isolated Cu 2+ . After hydrothermal treatment for 16 h, the amount of the inner nanosized CuO in the ion-exchanged sample reduced and the copper disperses to form more isolated Cu 2+ . However, surface CuO particles increase at the sacrifice of isolated Cu 2+ with extending the hydrothermal treatment to 24 h. Aggregation of Cu 2+ species also happens during the aging treatment over the one-pot prepared sample where the initial Cu is atomically dispersed as isolated Cu 2+ . The increase of the amount of the isolated Cu 2+ enhances the low-temperature (< 350 °C) performance. However, the increase of the amount of surface CuO particles in the aged samples promotes the nonselective NH 3 oxidation reaction in the high temperature range and results in the lowering of the SCR activity by limiting NH 3 supply.
研究领域:
环境科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2019
·
IF 8.355
Zhi Liu,Chong Chen,Jinchong Zhao,Lingzhi Yang,Kaian Sun,Lingyou Zeng,Yuan Pan,Yunqi Liu,Chenguang Liu
Selective catalytic reduction of NO by NH 3 (SCR) at low temperature usually considered to be the combination of NO oxidation and “Fast SCR” process. However, the NO oxidation mechanism and the role of NO 2 over “Fast SCR” process are controversial. Focusing on these problems, the in-deep studies were performed over the typical MnO x /TiO 2 catalysts. Combining in-situ DRIFT, TPD-MS and DFT calculation results, an integrated NO oxidation mechanism was proposed based on an “Nitro-assisted oxygen activation” concept where the activation and transformation of O 2 is linked with the transformation of nitro species. The O O bond of O 2 can be weakened by generating a variation of bidentate nitrates, which can promote the break of O O bond and the formation of NO 2 . The formation of the variation of bidentate nitrates was the rate-determining step over NO oxidation. Additionally, we further reveal that the crucial role of NO 2 over “Fast SCR” process lies in participating the hydrogen abstraction from coordinated NH 3 and promoting the production of NH 2 active species which can direct react with NO to generate N 2 and H 2 O. The removability of NO 2 can coupling the MnO 2 (NO oxidation active component) and TiO 2 support (“Fast SCR” active component) together. Our findings provide insight into the design and improvement of catalysts or reaction pathways over the low-temperature SCR process.
研究领域:
环境科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
RSC Advances
·
2018
·Vol. 8
·期 5
·2586-2592
·
IF 2.936
Boyang Xu,Youlin Liu,Yuesong Shen,Shemin Zhu
A facile method is to prepare novel CeMoxOy-clay hybrid catalysts with layered structures by using organic cation modified clay as support. During the preparation process, cerium cations and molybdate anions are easily adsorbed and impregnated into the interlamellar space of the organoclay, and after calcination they undergo transformation to highly dispersed CeMoxOy nanoparticles within the interlamellar space of the clay. As expected, the prepared CeMo0.15Ox-OC-T catalysts with layered structures had high selective catalytic reduction (SCR) activity such as high NOx conversion of >90% in the wide temperature range of 220–420 °C. Meanwhile, they also exhibit high stability and tolerance to water vapor (5 vol%) and SO2 (200 ppm), demonstrating that these novel catalysts could serve as a good alternative for NH3-SCR in practical application.
研究领域:
催化化学
·
环境科学
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY
·
2013
·
IF 2.145
Rui-tang Guo,Wen-long Zhen,Wei-guo Pan,Yue Zhou,Jie-nan Hong,Hong-jian Xu,Qiang Jin,Cheng-gang Ding,Shi-yi Guo
CeO 2 –CuO catalyst prepared by citric acid method was investigated for selective catalytic reduction of NO with NH 3 . The activity of the CeO 2 catalyst was enhanced about 8–27% in the temperature range of 125–225 °C at a space velocity of 28,000 h −1 by the addition of Cu. It was found that the state of Cu species had great impact on the SCR performance of CeO 2 –CuO catalyst. Cu 2+ can enhance the low temperature activity of SCR reaction, while CuO would promote NH 3 oxidation before SCR reaction at high temperature, which would cause the decrease of its high temperature SCR activity.
研究领域:
化学工程
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF NANOPARTICLE RESEARCH
·
2019
·Vol. 21
·期 4
·1-7
·
IF 2.009
Xie Chong,Shi Jian-Wen,Yang Shenghui,Li Xifei
The MnO x -TiO 2 /MWCNTs nanocomposites were used as De-NO x catalysts to study the deep-rooted reason for the deactivation. Based on a series of characterization on as-prepared catalyst and poisoned catalyst, the results showed that the chief culprit for the deactivation is the micropores in the De-NO x catalyst. The formed ammonium (bi)sulfate in the micropores during the SCR reaction process could not be took away by the gas flow soon and then deposited on the catalyst surface gradually, and further covered the active sites. And the poisoned catalysts could be recovered partly rather than fully by heat treatment at 500 °C because of the decomposition of the ammonium (bi)sulfate and the phase transition of the TiO 2 .
研究领域:
环境催化
·
纳米材料科学
·
大气污染控制
✓ 已验证
DOI
高影响因子
ENVIRONMENTAL SCIENCE & TECHNOLOGY
·
2025
·
IF 11.3
Zhiqiang Zhang,Baiyun Zhu,Lu Xu,Yan Wang,Jiawei Ji,Wang Song,Meilin Tao,Changjin Tang,Lin Dong
Alkali metal poisoning represents a formidable challenge for the effective utilization of ammonia selective catalytic reduction (NH3–SCR) technology. Herein, we propose a versatile strategy to radically circumvent the deactivation effect from alkali metals via regulated activation of surface NOx species. Activity test showed that after physical mixing with a series of zeolites (ZSM-5, MOR, and SAPO-34), the activity of the K-poisoned CeO2–MnOx catalyst achieved complete recovery, and the observed NO conversion was found to be even superior to that of the fresh catalyst. Mechanism analysis from in situ DRIFTS and TPSR revealed that K deposition shut off the transformation of surface NOx from chelating bidentate nitrites to bidentate nitrates (both bridging and chelating bidentate nitrates), leading to catalyst deactivation. Zeolite coupling introduced labile NO+ species, which interacted facilely with the chelating bidentate nitrites to generate chemically reactive bidentate nitrates, enabling a thorough regeneration of NH3–SCR performance. In addition to CeO2–MnOx, this strategy was also found to be valid for a variety of NH3–SCR catalysts, demonstrating great potential in reversing alkali metal poisoning.
研究领域:
环境科学
·
催化化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Materials Research Express
·
2021
·Vol. 8
·期 4
·045509
·
IF 1.62
Ruian Wu,Jiang Jin,Kun Li,Lei Zhao,Hua Zhang
The FeaTibOx catalyst was loaded into the pores of porous ceramic using impregnation method for removing nitrogen oxides with selective catalytic reduction (SCR) technology. The catalytic performance over FeaTibOx catalyst was studied in detail. The Fe6Ti1Ox catalyst displayed more than 95% NOx conversion within the range of 280 °C–400 °C, and still maintained 97% NOx conversion when 300 ppm SO2 and 10 vol.% water vapor were introduced at the testing temperature of 300 °C. The influence factors (including filtration velocity, NH3/NO mole ratio and oxygen concentration) for NOx conversion over Fe6Ti1Ox catalyst were also studied. The suitable NH3/NO mole ratio and oxygen concentration was 0.9 and 6%, respectively. The XRD, N2-BET, H2-TPR, NH3-TPD and XPS were employed to investigate physicochemical property of the FeaTibOx catalyst. The results illustrated that Fe6Ti1Ox catalyst has hematite Fe2O3 and TiO2 structure, better redox properties and stronger surface acid.
研究领域:
环境科学
·
催化材料
✓ 已验证
DOI
高影响因子
CATALYSIS TODAY
·
2016
·
IF 4.312
Xuesong Liu,Xiaodong Wu,Duan Weng,Zhichun Si,Rui Ran
Cu-modified SAPO-34 molecular sieves with different Cu loading amounts were prepared by ion-exchange and impregnation methods. Both series of catalysts were hydrothermally treated at 750 °C in 10 vol% H 2 O/air for 24 h. The catalysts were characterized by inductively coupled plasma optical emission spectrometry (ICP-OES), electron paramagnetic resonance (EPR), X-ray photoelectron spectroscopy (XPS), H 2 temperature-programmed reduction (H 2 -TPR), NH 3 temperature-programmed desorption (NH 3 -TPD) and diffused reflectance infrared flourier transform spectroscopy (DRIFTS). All the fresh catalysts show high activity toward the selective catalytic reduction of NO x with NH 3 (NH 3 -SCR) at low temperatures regardless of preparation method. Generally, the hydrothermal aging shifts the operation window of the catalysts towards high temperatures. The improvement in high-temperatures activity is attributed to the migration of surface CuO clusters into the ion-exchanged sites as isolated Cu 2+ during ageing, which suppresses the competitive oxidation of NH 3 . The loss of low-temperatures activity is also related to the decrease in the amount of active surface CuO clusters, inhibiting the oxidation of NO to NO 2 and fast SCR reaction. Interestingly, the amount of Lewis acid sites increase linearly with the increasing isolated Cu 2+ , while the Brønsted acidity is weakened.
研究领域:
催化化学
·
环境科学
✓ 已验证
DOI
高影响因子
INTERNATIONAL JOURNAL OF COAL GEOLOGY
·
2016
·
IF 3.294
Hailong Li,Lei Zhu,Shaokang Wu,Yang Liu,Kaimin Shih
Synergy for low temperature Hg 0 oxidation under selective catalytic reduction (SCR) atmosphere was achieved when copper oxides and cerium oxides were combined in a CuO-CeO 2 /TiO 2 (CuCeTi) catalyst. Hg 0 oxidation efficiency as high as 99.0% was observed on the CuCeTi catalyst at 200 °C, even the gas hourly space velocity was extremely high. To analyze the synergistic effect , comparisons of catalyst performance in the presence of different SCR reaction gases were systematically conducted over CuO/TiO 2 (CuTi), CeO 2 /TiO 2 (CeTi) and CuCeTi catalysts prepared by sol-gel method. The interactions between copper oxides and cerium oxides in CuCeTi catalyst yielded more surface chemisorbed oxygen, and facilitated the conversion of gas-phase O 2 to surface oxygen, which are favorable for Hg 0 oxidation. Copper oxides in the combination interacted with NO forming more chemisorbed oxygen for Hg 0 oxidation in the absence of gas-phase O 2 . Cerium oxides in the combination promoted Hg 0 oxidation through enhancing the transformations of NO to NO 2 . In the absence of NO, NH 3 exhibited no inhibitive effect on Hg 0 oxidation, because enough Lewis acid sites due to the combination of copper oxides and cerium oxides scavenged the competitive adsorption between NH 3 and Hg 0 . In the presence of NO, although NH 3 lowered Hg 0 oxidation rate through inducing reduction of oxidized mercury, complete recovery of Hg 0 oxidation activity over the CuCeTi catalyst was quickly achieved after cutting off NH 3 . This study revealed the synergistic effect of the combination of copper oxides and cerium oxides on Hg 0 oxidation, and explored the involved mechanisms. Such knowledge would help obtaining maximum Hg 0 oxidation co-benefit from SCR units in coal-fired power plants.
研究领域:
环境科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
Inorganic and Nano-Metal Chemistry
·
2021
·
IF 1.716
Changsheng Qu,Hao Zhou,Dongyao Xu,Jiaojiao Guo,Danyang Zhao,Xuewei Guo,Luyuan Xing
In this study, the manganese was loaded on three different zirconia crystal types by ultrasonic impregnation method, and the performance of selective catalytic reduction (SCR) of NOx with NH3 was tested. The characteristics of the catalytic were tested by BET, XRD, SEM, and XPS. It was founded that the performances of unloaded different crystal zirconia was basically the same which were less than 40%. Compared with unloaded catalyst, the DeNOx performance of catalysts after loaded manganese was greatly improved, and the crystal type had obvious influence on the DeNOx performance of Mn/x-ZrO2. The Mn/m-ZrO2 had the highest DeNOx performance (90.97% at 240 °C) compared with the Mn/t-ZrO2 and Mn/c-ZrO2. The difference of crystal type made Mn/m-ZrO2 have lower surface Mn average valence states and more oxygen vacancy, which made it have best DeNOx performance. The effects of SO2, H2O, and alkali metal on DeNOx efficiency were also tested.
研究领域:
环境科学
·
催化材料科学
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2020
·
IF 10.652
Yiqing Zeng,Yanan Wang,Plaifa Hongmanorom,Zhigang Wang,Shule Zhang,Jiatang Chen,Qin Zhong,Sibudjing Kawi
Highly-efficient CeO 2 -TiO 2 -based catalyst is an attractive alternative to traditional V 2 O 5 -based catalysts for selective catalytic reduction of NO x by NH 3 (NH 3 -SCR). Herein, we construct an efficient and stable P-doped CeO 2 /TiO 2 ( y CeTi-P x ) catalyst by dispersing CeO 2 on strongly acidic and highly stable mesoporous P-doped TiO 2 (Ti-P x ). The characteristic structure of Ti-P x causes highly dispersed CeO 2 , strong active component-support interaction, and abundant surface active oxygen and acid sites on CeTi-P catalyst. Therefore, y CeTi-P x catalyst exhibits much higher catalytic activity than y CeTi catalyst at temperature of 200–450 °C. The y CeTi-P x catalysts show high activity in the presence of H 2 O and strong resistance to H 2 O + SO 2 at medium-high temperature, implying that they have great industrial application prospects. Different P/Ti ratio and CeO 2 loading content were investigated. Excessive P doping can block the Ce 4+ /Ce 3+ redox couple, and suppress redox sites on y CeTi-P x catalyst. Additionally, increasing CeO 2 content can reduce the NH 3 capacity of y CeTi-P x catalyst. By controlling the P/Ti ratio and CeO 2 loading content, surface acid sites and redox sites on y CeTi-P x catalyst can be balanced to obtain the best catalytic activity. This work demonstrates a feasible method in adjusting acid sites and redox sites on CeTi catalyst, which ultimately contributes to the new design of CeO 2 -TiO 2 -based catalyst.
研究领域:
环境科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）