Catalysts
·
2020
·Vol. 10
·期 11
·1329
·
IF 3.52
Shijie Hao,Yandi Cai,Chuanzhi Sun,Jingfang Sun,Changjin Tang,Lin Dong
Monolithic Mn-Fe-Ce-Al-O catalyst with honeycomb cordierite ceramic as a carrier was reported for the first time for low temperature deNOxapplication. In the reaction of selective catalytic reduction (SCR) of NO with NH3, a NO conversion of above 80% at 100 °C was obtained. Notably, the catalyst also showed excellent resistance against SO2and H2O. About 60% NO conversion was maintained after successive operation in the mixed stream of SO2and H2O for 168 h. The Brunner−Emmet−Teller (BET) measurement, SEM, EDS, thermogravimetric analysis (TG), FT-IR, and XPS results of the used catalysts indicated that certain amounts of ammonium sulfate was formed on the surface of the catalyst. XPS results revealed that partial of Fe2+was oxidized to Fe3+during the reaction process, and Fe2+species have strong redox ability, which can explain the decrease in activity after reaction. In addition, SO2and H2O induced a transformation of Ce from Ce4+to Ce3+on the surface of the catalyst, which increased the amount of chemisorbed oxygen. Owing to these factors, the addition of Ce and Fe species contributes to excellent resistance of the catalyst to SO2and H2O.Keywords:honeycomb catalyst;Mn-Fe-Ce-Al-O;low temperature denitration;water and sulfur resistance
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
RESEARCH ON CHEMICAL INTERMEDIATES
·
2018
·Vol. 44
·期 5
·3135-3150
·
IF 1.674
Wang Cheng-zhi,Zhao Yong-gang,Zhang Cheng,Yan Xin,Cao Peng
Honeycomb cordierite-based Mn–Ce/Al 2 O 3 (Mn–Ce/Al 2 O 3 –C) and Fe–Mn–Ce/Al 2 O 3 (Fe–Mn–Ce/Al 2 O 3 –C) catalysts were prepared by an impregnation method and investigated in low-temperature selective catalytic reduction (SCR) of NO with NH 3 at 100 °C. The Fe–Mn–Ce/Al 2 O 3 –C catalyst exhibited not only higher catalytic activity, but also much better SO 2 and H 2 O resistance in the presence of 30 ppm SO 2 and/or 5 vol% H 2 O than Mn–Ce/Al 2 O 3 –C. After doping Fe, the NO conversion of Mn–Ce/Al 2 O 3 –C catalyst displayed an increasing trend from 79 to 84% in the absence of SO 2 and H 2 O at 100 °C under a gas hour space velocity of 1667 h −1 . The results of characterization indicated that addition of Fe was advantageous to increase BET surface area, pore volume and inhibit loss of surface Mn and Ce species. Additionally, it was helpful for generating higher concentration of Mn 4+ , more chemisorbed oxygen and more uniform dispersion of amorphous Mn and Ce in the surface of catalyst, which were beneficial to interact with reactants. Furthermore, in contrast to Mn–Ce/Al 2 O 3 –C, the SCR activity of Fe–Mn–Ce/Al 2 O 3 –C catalyst in the presence of H 2 O, SO 2 and H 2 O and SO 2 were 79, 75 and 64%, with the increase of 14, 18 and 19%, respectively. It is indicated that the addition of Fe could inhibit sulfate formation and thus enhance SO 2 resistance. XPS results reveal that the doping of Fe into the ceria lattice led to some Ce 4+ transferred into Ce 3+ in order to maintain the electrical neutrality, thereby facilitating the reduction of Ce 4+ → Ce 3+ and the formation of oxygen vacancies. NH 3 temperature-programmed desorption (TPD) results imply that the doping of Fe onto Mn–Ce/Al 2 O 3 –C can remarkably improve the distribution and concentration of acid sites. All the above factors contributed to the improvement of overall NH 3 SCR performance of the Fe–Mn–Ce/Al 2 O 3 –C catalyst compared with that of the Mn–Ce/Al 2 O 3 –C 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
CHEMICAL ENGINEERING SCIENCE
·
2022
·
IF 4.889
Wuyuan Liu,Zihan Gao,Ming Sun,Jiajian Gao,Lifeng Wang,Xiangyun Zhao,Runnong Yang,Lin Yu
A series of Cr α Mn β CeTiO x catalysts were prepared using one-pot precipitation method and evaluated for the selective catalytic reduction (SCR) of NO with ammonia. Among the catalysts prepared, the Cr 0.006 Mn 0.05 CeTiO x catalyst exhibited the highest low-temperature activity and widest activity window (＞90% NO conversion at 160–425 °C) as well as outstanding sulfur resistance. The catalysts were characterized using XRD, NH 3 /NO/SO 2 + O 2 -TPD, XPS, in situ DRIFT, and so on. The amorphous Cr 0.006 Mn 0.05 CeTiO x catalyst had a larger specific surface area, high ammonia adsorption and strong acidity, resulting in an improved catalytic activity. A high ratio of surface adsorption oxygen and Ce 3+ promoted the formation of NO 2 , a key intermediate gas in the fast SCR reaction. Furthermore, in situ DRIFT showed that the SCR reaction followed the Eley Rideal and Langmuir Hinshelwood mechanisms. Moreover, the synergetic effect of Cr and Mn inhibited the accumulation of hydrogen sulfate or sulfate considerably.
研究领域:
催化化学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
PROCESS SAFETY AND ENVIRONMENTAL PROTECTION
·
2022
·
IF 7.926
Shuangli He,Jinghang Ren,Peng Cao
Low-temperature selective catalytic reduction (SCR) is effective and promising for converting NO x in flue gas into N 2 , with wide application prospects. However, low-temperature denitration (DeNO x ) catalysts are susceptible to SO 2 and H 2 O poisoning. Here, we prepared a monolithic Mn-Fe-Ce/Al 2 O 3 catalyst that exhibited excellent DeNO x performances at low temperatures. At 110 °C, the NO conversion rate of the catalyst was> 90%, exhibiting excellent resistances to H 2 O and SO 2 ·H 2 O and SO 2 are introduced at the same time, the efficiency is as high as 73%. Furthermore, The catalyst has a porous structure with abundant chemisorbed oxygen spices and exposed active, the reaction pathway on the catalyst proved to be the L-H mechanism based on in situ DRIFTS. This study also explored the mechanisms of low-temperature SCR catalyst poisoning by SO 2 and H 2 O, providing insights into the effects of SO 2 and H 2 O and theoretical support for the development of poisoning-resistant low-temperature SCR catalysts.
研究领域:
环境科学
·
催化材料
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2024
·
IF 6.7
Liang-Liang Zhang,Kai-Xuan Yang,Cai-Long Xue,Wan-Xi Li,Bo-Qiong Li,Yi-En Du,Yong-Qiang Chen,Ya-Jie Liu
The design of an active and sulfur-resistant catalyst for dibenzothiophene (DBT) hydrodesulfurization (HDS) in crude oil purification is highly desirable but remains a grand challenge. Here, two carbon-supported cobalt phosphide catalysts Co 2 P/C and CoP/C, and a reference sample Co/C are successfully synthesized using a metal–organic-frameworks (MOFs) precursor. A P/Co ratio dependence on crystal phases is found, leading to the formation of two pure-phase cobalt phosphide catalysts CoP/C and Co 2 P/C. Catalyst evaluation in HDS of DBT shows that the CoP/C catalyst exhibits a higher activity and stability than Co 2 P/C and Co/C, giving a 93.7 % DBT conversion with 100 h stability under 3 MPa and 380 ◦C. Moreover, a 67.4 % biphenyl yield characterizes the dominance of the direct desulfurization (DDS) pathway. The obtained catalytic performance over the CoP/C catalyst is also superior to the published cobalt phosphide catalysts. Multiple characterization techniques co-evidence that the copious specific surface area, efficient electron transport from Co to P, high thermal stability of Co nanoparticles (NPs), and strong sulfur resistance account for the enhanced catalytic performance of CoP/C. The findings of this report suggest that phosphorus-modified cobalt over the carbon support can act as a promising catalyst for the HDS of DBT.
研究领域:
催化化学
·
能源材料科学
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2020
·
IF 10.652
Zhicheng Xu,Yuran Li,Junxiang Guo,Jin Xiong,Yuting Lin,Tingyu Zhu
In this work and for the first time, an alkali metal potassium (K) as a promoter was loaded on an activated carbon (AC) to be used for selective catalytic reduction of NO from industrial flue gas. The denitrification activity of K-modified AC samples was investigated and compared with those of acid- and Cu-modified AC samples. The three modifications can enhance the denitrification activity of AC samples. To investigate the enhanced mechanisms of denitrification and SO 2 resistance, various AC samples were characterized by SEM, EDX, XRF, ICP, XRD, N 2 physisorption, H 2 -TPR, XPS, in situ DRIFTS and TPD. For the acid modification, the content of phenolic hydroxyl increases and then promotes the adsorption of NH 3 . For the loading of Cu, the appearance of Cu 2+ /Cu + sites with high catalytic activity promotes NH 3 and NO adsorption and changes the reaction pathway. For the loading of K, the adsorption capacity for NO increases nearly 12 times higher than that on Raw-AC, of which 85.0% is chemical adsorption. Moreover, three kinds of active nitrate species additionally forms, including nitro compounds, monodentate nitrate and nitrous oxide, which promote the denitrification reaction path. AC-Cu has poor sulfur resistance due to the sulfation of Cu, while AC-K show good sulfur resistance due to the enhanced adsorption of NO. The catalytic dissociation activity of N 2 O on AC-K makes the formation and decomposition of N 2 O into a dynamic equilibrium. As a result, AC-K has a high N 2 selectivity , while AC-Cu has poor N 2 selectivity.
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
RSC Advances
·
2023
·Vol. 13
·期 29
·19965-19974
·
IF 3.9
Lei Sun,Zhenzhen Wang,Mengxi Zang
In view of the characteristics of high temperature denitrification and low water and sulfur resistance of single manganese-based catalysts, a vanadium–manganese-based ceramic filter (VMA(14)-CCF) was prepared by the impregnation method modified with V. The results showed that the NO conversion of VMA(14)-CCF was more than 80% at 175–400 °C. At 225–300 °C, the conversion of NO can reach 100%. High NO conversion and low pressure drop can be maintained at all face velocities. The resistance of VMA(14)-CCF to water, sulfur and alkali metal poisoning is better than that of a single manganese-based ceramic filter. XRD, SEM, XPS and BET were further used for characterization analysis. The introduction of V protects the MnOx center, promotes the conversion of Mn3+ to Mn4+, and provides abundant surface adsorbed oxygen. The development of VMA(14)-CCF greatly broadens the application range of ceramic filters in denitrification.
研究领域:
环境科学
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
iScience
·
2022
·
IF 6.107
Meng Wang,Yan Zhang,Wenpo Shan,Yunbo Yu,Jingjing Liu,Hong He
The thermal stability of the catalysts is of particular importance but still a big challenge for working under harsh conditions at high temperature. In this study, we report a strategy to improve the thermal stability of the ceria-based catalyst via introducing Sn. XRD, Rietveld refinement, and other characterizations results indicated that the formation of Sn-Co solid solution plays a key role in the thermal stability of the catalyst. The developed ternary 3%Co/Ce 0.5 Sn 0.5 O 2 catalyst not only exhibits outstanding thermal stability and resistance to SO 2 and H 2 O for soot oxidation from diesel vehicle exhaust but also remains extraordinary thermal stability for CO oxidation. Remarkably, even after thermal aging at 1000°C, it still possessed high catalytic activity similar to that of the fresh catalyst.
研究领域:
催化材料
·
环境科学
·
化学工程
✓ 已验证
DOI
PubMed
高影响因子
Catalysis Science & Technology
·
2024
·
IF 4.4
Zhicheng Xu,Jin Xiong,Yuran Li,Junxiang Guo,Bin Wang,Tingyu Zhu
For industrial flue gas purification at medium and low temperatures, it is highly necessary to promote the denitrification activity of V-based catalysts in a SO2 atmosphere. Transition metals (Ce, Co, Fe, and Mn) are used to modify V/Ti catalysts to improve SO2 resistance with ammonium bisulfate deposition on the catalysts. Sulfation on Ce with less ammonium bisulfate deposition considerably improves the SO2 resistance of V1Ce5/Ti, and stable sulfation on TiO2 promoted by Co provides additional Brønsted acid sites for V1Co5/Ti to reduce the deactivation. Serious sulfation on V1Mn5/Ti with large ammonium bisulfate deposition on V1Fe5/Ti causes deeper deactivation. The formation mechanism of ammonium bisulfate on active metal sites and TiO2 carriers has been clarified. SO2 is adsorbed on V sites and transition metal sites followed by oxidation and ammoniation or adsorbed on TiO2 carriers followed by ammoniation and oxidation. The first pathway is more dominant than the second pathway in the presence of O2 with the co-oxidation of SO2 by O2 and lattice oxygen. The initial formation temperature and stable temperature of dominant intermediates were determined by in situ DRIFTS. SO2 adsorbed on TiO2 carriers is oxidized by V sites above 170 °C to form a tridentate sulfate, while SO2 adsorbed on transition metal sites is initially oxidized by transition metal sites above 50 °C to form monodentate and bidentate sulfates, as well as competitively oxidized by V sites above 170 °C to form tridentate sulfates. The selective adsorption of SO2 on transition metal sites or TiO2 carriers and the competitive oxidation of SO2 by transition metal sites and V sites provide a synergistic effect between V sites and transition metal sites to reduce ammonium sulfate deposition and release more active sites. These findings provide theoretical guidance to design and prepare V-based catalysts with high denitrification activity in the presence of SO2.
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
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2024
·
IF 20.2
Mengyuan Zhang,Xiaoyan Lu,Kongliang Luo,Jian Ye,Jia li Dong,Nana Lu,Xiaopeng Wang,Qiang Niu,Pengfei Zhang,Sheng Dai
Ubiquitous presence of SO 2 usually shows adverse effects on industrial catalysis. Herein, a concept of engineering entropy to design SO 2 resistance oxide catalysts is proposed. (Ni 0.2 Mg 0.2 Cu 0.2 Zn 0.2 Co 0.2 )Fe 2 O 4 showed excellent performance (the CO 2 conv. = 41.4%, CO selec. = 99.6% at 400°C) compared to the control samples in the reverse water–gas shift (RWGS). In addition, (Ni 0.2 Mg 0.2 Cu 0.2 Zn 0.2 Co 0.2 )Fe 2 O 4 had the SO 2 -tolerant ability (the CO 2 conv. = 38.5%, CO selec. = 99.2% at 400°C) after being poisoned with 1000 ppm SO 2 at 400°C for 1 h. In sharp contrast, the control samples NiFe 2 O 4, MgFe 2 O 4, CuFe 2 O 4 and CoFe 2 O 4 lost their activity. O 1S XPS indicated that (Ni 0.2 Mg 0.2 Cu 0.2 Zn 0.2 Co 0.2 )Fe 2 O 4 had higher oxygen vacancy concentrations. SO 2 resistance mechanism was studied by infrared spectroscopy, SO 2 -TPD, in situ S 2p XPS and the DFT results, confirming that the low SO 2 adsorption energy of (Ni 0.2 Mg 0.2 Cu 0.2 Zn 0.2 Co 0.2 )Fe 2 O 4 , which was attributed to the lower Gibbs free energy. This work may inspire the rational design of SO 2 -resistant catalysts.
研究领域:
催化化学
·
材料科学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
ACS Catalysis
·
2022
·
IF 13.7
Xiaoyan Liu,Yiqi Ren,Maodi Wang,Xiaomin Ren,Jian Liu,Qihua Yang
Selective hydrogenation of nitrobenzothiazole to aminobenzothiazole with metal catalysts is an economical process for the synthesis of pivotal intermediates for thiazole drugs, but it is still very difficult due to the easy deactivation of metal catalysts by sulfur-containing compounds. Herein, we report efficient nitrobenzothiazole hydrogenation using Pt/TiO2 as a catalyst. Pt/TiO2 with the strong metal–support interaction (SMSI) effect was found to be more active than Pt/TiO2 without the SMSI effect. Density functional theory (DFT) calculations and S-resistance experiments revealed that the −NO2 group is activated mainly by the oxygen vacancy (Ov) of TiOx in the presence of sulfur compounds and that H species dissociated on Pt spills over to reduce −NO2. The high nitrobenzothiazole hydrogenation activity of Pt/TiO2 can be attributed to a cooperative effect between Pt and TiOx. The generation of SMSI not only induces more Ov sites but also enhances the H-spillover capability. This study provides deep insight into the development of highly efficient platinum-S resistance hydrogenation catalysts.
研究领域:
催化化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2021
·
IF 8.128
Xiaolong Tang,Chengzhi Wang,Fengyu Gao,Runcao Zhang,Yiran Shi,Honghong Yi
Improving the SO 2 resistance of catalysts is crucial to driving commercial applications of Mn-based catalysts. In this work, the phosphotungstic acid (HPW) modification strategy was applied to improve the N 2 selectivity , SO 2 and H 2 O resistance of the Mn-Ce-Co catalyst, and further, the mechanism of HWP modification on enhanced catalytic performance was explored. The results showed that HPW-Mn-Ce-Co catalyst exhibits higher NO x conversion (~100% at 100–250 °C) and N 2 selectivity (exceed 80% at 50–350 °C) due to more oxygen vacancies , greater surface acidity , and lower redox capacity. In situ diffused reflectance infrared Fourier transform spectroscopy (in situ DRIFTS) reveal that HPW changed the reaction path of Mn-Ce-Co catalysts, promoted the adsorption and activation of NH 3 , and reduced the effect of SO 2 on the active bidentate nitrate species, and thereby exhibiting good SO 2 resistance. X-ray photoelectron spectrometer (XPS) and NH 3 temperature-programmed desorption of (NH 3 -TPD) results show that HPW can inhibit the formation of metal sulfate , and SO 2 can be combined with Ce species more easily. The generated Ce 2 (SO 3 ) 3 can not only protect Mn species but also increase the acid sites and weaken the poisoning effect of metal sulfate . This study provides a simple design strategy for the catalyst to improve the low-temperature catalytic performance and toxicity resistance.
研究领域:
催化化学
·
环境科学
✓ 已验证
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）