ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
·
2024
·
IF 0
You Mengyun,Wu Shufeng,Feng Xiaotong,Zhao Yong,Wang Yubin,Zhang Zhang
The enhancement effect of Ce modification on V 2 O 5 -WO 3 /TiO 2 catalysts at low temperatures was investigated for the selective catalytic reduction (SCR) of NO x with NH 3 (NH 3 -SCR). By adding 9% CeO 2 to 0.5%V 2 O 5 -3%WO 3 /TiO 2 catalyst, the low-temperature denitrification performance of Ce 9 V 0.5 W 3 Ti catalyst after Ce modification was significantly improved, achieving a NO conversion above 90% within a broad temperature range of 200–350℃, with catalytic activity comparable to that of 3% V 2 O 5 -3% WO 3 /TiO 2 . The catalysts were characterized by XPS, H 2 -TPR, NH 3 , and NO-TPD. The results indicated that the Ce additive could enhance the adsorption of NO x on Ce 9 V 0.5 W 3 Ti catalyst due to the synergetic interaction among the Ce and V, W species. The interaction between V and Ce also promoted the formation of V 5+ and Ce 3+ on the surface of the catalyst, which was conducive to enhancing the adsorption and oxidation capacity of the catalyst for NO. Additionally, the introduction of Ce led to a substantial deposition of nitrate species on the surface of the catalyst, especially the increase of nitrite species, which was beneficial to the NH 3 -SCR reaction process, resulting in a significant enhancement of the catalyst’s low-temperature catalytic activity.
研究领域:
环境科学
·
催化化学
✓ 已验证
产品关联
DOI
PubMed
PROCESS SAFETY AND ENVIRONMENTAL PROTECTION
·
2022
·
IF 7.926
Wei Li,Xuesen Du,Zhi Li,Yaqin Tao,Jingyu Xue,Yanrong Chen,Zhongqing Yang,Jingyu Ran,Vladislav Rac,Vesna Rakić
Vanadia-based catalysts are widely used in selective catalytic reduction (SCR) reaction for reducing nitrogen oxides emissions, however, they only exhibit sufficient DeNO x efficiency within a narrow temperature window. In this study, a catalyst embedded with electrothermal alloy was prepared. The catalyst surface temperature could be heated using the electrothermal alloy, in order to widen the operating temperature window of the V 2 O 5 -WO 3 /TiO 2 catalyst. Experimental results revealed that the electrothermal alloy embedded V 2 O 5 -WO 3 /TiO 2 catalyst can maintain superior NH 3 -SCR performance and high resistance to H 2 O in a wide gas temperature range of 100–400 °C by controlling the surface temperature. In the meantime, the NH 4 HSO 4 poisoned catalyst could be efficiently regenerated through electric heating, and NO x conversion can be restored to the level of fresh samples. Additionally, the effect of additives including methylcellulose and glass fiber , on the physicochemical properties of the plate-type catalyst was also investigated, and the catalyst samples were characterized by means of BET, XRD , NH 3 -TPD, H 2 -TPR, TG and SEM-EDS. This study proves the electric heating strategy is a promising way to enhance the performance of the V 2 O 5 -WO 3 /TiO 2 during wide temperature SCR applications.
研究领域:
环境科学
·
催化化学
✓ 已验证
DOI
高影响因子
FUEL
·
2022
·
IF 8.035
Yiqing Zeng,Weilong Rong,Shule Zhang,Yanan Wang,Qin Zhong
Ammonia selective catalytic reduction (NH 3 -SCR) technique for nitrogen oxide (NO x ) elimination of low temperature flue gas (<200 °C) requires huge energy consumption and operation costs. In this work, a CuO modified V 2 O 5 -WO 3 /TiO 2 (Cu/VWTi) catalyst are constructed to achieve the aim of enhancing the temperature of flue gas via using the heat released by CO oxidation, thereby promoting the NH 3 -SCR of NO x reaction. Benefiting from the synergistic effect between CuO and VWTi in the adsorption and activation of reactants, Cu/VWTi catalyst shows high NO x (>90%) and CO (>90%) removal efficiency at the temperature range of 225–270 °C and a GHSV of 40,000 h −1 . Moreover, it is found that the completely oxidation of 2000 ppm CO can increase the flue gas temperature by about 20 °C. Therefore, developing catalyst that can achieve simultaneously NH 3 -SCR of NO x and CO oxidation is a feasible method to deduce the energy consumption and operation costs of NH 3 -SCR of NO x system in low temperature flue gas. Finally, the reaction process and SO 2 deactivation effect over Cu/VWTi catalyst was studied via in-situ DRIFT. This work might provide some guidance for the design of catalysts to eliminate multiple pollutants.
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
SEPARATION AND PURIFICATION TECHNOLOGY
·
2023
·
IF 8.6
Xiangsen Xu,Fengye Lyu,Jiahao Chen,Yiqing Zeng,Zhaoxiang Zhong,Feng Zhang,Weihong Xing
In this work, TiO 2 nanocones grown on SiC membrane was used as the support of V 2 O 5 -WO 3 species to prepare V 2 O 5 -WO 3 /TiO 2 @SiC (VWTi(C-X)@SiC) catalytic membrane for dust filtration and NH 3 -SCR denitration. On account of the large specific surface area, abundant surface acid sites and prominent redox property, the optimized VWTi(C-550)@SiC catalytic membrane shows >90% NO removal efficiency at the temperature of 280–360 °C, which are much higher than VWTi(P-550)/SiC catalytic membrane (TiO 2 nanoparticles prepared by traditional vacuum coating titanium sol method was used as the support of V 2 O 5 -WO 3 species, NO conversion <80% at whole tested temperature). Additionally, VWTi(C-550)@SiC displays superior stability during the SO 2 + H 2 O resistance and 300 h long-term test at 300 °C, and exhibits an excellent dust filtration performance (2.5 μm SiO 2 particles interception rate exceeded 99.99%) under all test conditions. More importantly, the structure of nanocones decrease the influence of tensile stresses due to the different thermal expansion coefficients of TiO 2 and SiC membranes, which significantly suppress the fall of VWTi catalyst layer from the surface of SiC during pulse-jet cleaning. Among above results, it can be concluded that the optimized VWTi(C-550)@SiC catalytic membrane shows a prosperous application prospect for the simultaneously dust filtration and NH 3 -SCR denitration of medium–high temperature flue gas .
研究领域:
环境科学
·
催化材料
·
能源工程
✓ 已验证
产品关联
DOI
高影响因子
Asia-Pacific Journal of Chemical Engineering
·
2019
·Vol. 14
·期 3
·e2309
·
IF 1.396
Zulfiqar Ali,Qiang Lu,Tahir Iqbal,Zulqarnain Arain,Jian Han,Yang-wen Wu,Ding-jia Liu,Yong-ping Yang
Heavy metal Pb is an inevitable ingredient of coal-fired flue gas and has been proven to be a source of inhibiting effect on the selective catalytic reduction (SCR) catalyst. In this paper, two types of Pb-poisoned catalyst, prepared by the incipient wetness impregnation and solid diffusion methods, are studied to unveil the poisoning effects of lead species on the V 2 O 5 -WO 3 /TiO 2 catalyst. The activity test results showed that lead species loaded by the incipient wetness impregnation method exhibited a significant inhibiting effect on the denitrification efficiency of the catalyst although a negligible activity loss was observed on the samples from the solid diffusion method. Characterizations of fresh and Pb-poisoned catalysts from incipient wetness impregnation method were applied using comprehensive techniques such as X-Ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), X-ray fluorescence (XRF), NH 3 -temperature programmed desorption (NH 3 -TPD), X-Ray photoelectron spectroscopy (XPS), and so forth. The analytical results indicated that a phase transformation occurred in tungsten species and the amorphous WO 3 converted into PbWO 4 , causing the accumulation and valence imbalance of active vanadium phase, which further decreased the surface acidity and activity of the V 2 O 5 -WO 3 /TiO 2 catalyst.
研究领域:
环境科学
·
催化材料
✓ 已验证
DOI
高影响因子
FUEL
·
2023
·
IF 7.4
Chong Xia,Yuanqing Zhu,Song Zhou,Yongming Feng,Jie Shi
Besides catalyzing NOx reduction, the V 2 O 5 -WO 3 /TiO 2 catalyst can effectively suppress the formation of urea (CH 4 N 2 O) decomposition by-products in selective catalytic reduction (SCR). However, current research lacks a clear understanding of the impact of urea and its by-products on the catalyst' performance. Additionally, there is no available kinetic model to describe the decomposition process of urea and its by-products on the V 2 O 5 -WO 3 /TiO 2 catalyst. In this paper, the decomposition process of urea and its by-products on the catalyst was firstly investigated via thermogravimetric analysis (TGA). It was found that increasing the catalyst dosage can accelerate urea decomposition and block the transformation pathways from urea and biuret (C 2 H 5 N 3 O 2 ) to cyanuric acid (cya, C 3 H 3 N 3 O 3 ). However, as the decomposition temperature of the by-products increased, a larger amount of catalyst was also required. Secondly, the impact of urea and its by-products on the NOx reduction performance was investigated via the SCR test bench. The results showed that, at 200 ℃, the addition of 20 % urea, biuret, or cya decreased the NOx reduction rate by 7.2 %, 9.8 %, and 11.0 % respectively. Furthermore, the catalyst's performance was significantly improved at 400 ℃ dues to the decomposition of urea and its by-products. Then, various characterization techniques were used to analyze the morphology and chemical composition of the urea decomposition products on the catalyst at different temperatures. On this basis, a simplified urea non-catalytic and catalytic coupling mechanism model was developed, which included 7 species and 16 reactions. Finally, the kinetic parameters of the proposed urea catalytic decomposition model were optimized utilizing TGA test data, density functional theory (DFT), and genetic algorithms (GA). This study can provide guidance for the elimination of SCR urea deposits in engineering applications.
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
Journal of the Taiwan Institute of Chemical Engineers
·
2022
·
IF 5.477
Kaiwen Ni,Yuewang Peng,Geyu Dai,Huawang Zhao,Zhiwei Huang,Xiaomin Wu,Guohua Jing,Wei Feng,Ye Yuan
Background Ammonia bisulfate (ABS) deposition on the active sites of the catalyst surface is the main reason for SO 2 poisoning in low-temperature NH3-selective catalytic reduction (SCR). Accelerated ABS decomposition efficiently enhances the SO 2 resistance. Methods In this work, ceria was specifically chosen to decorate V 2 O 5 -WO 3 /TiO 2 catalyst (Ce-VW/Ti) to activate ABS decomposition in low-temperature NH 3 -SCR. Significant findings The optimal 7Ce-VW/Ti catalyst accelerated the decomposition of ABS and had superior SO 2 tolerance at 250°C. The additive CeO 2 improved the specific surface area and surface acidity, favoring the NH 3 -SCR catalytic activity. ABS was preferentially deposited on the additive CeO 2 on the surface of the 7Ce-VW/Ti catalyst and generated cerium sulfate, eventually protecting the active V 2 O 5 sites and TiO 2 support. Moreover, high quantity of V 5+ and charge transfer between active species V 2 O 5 and support TiO 2 could be maintained due to CeO 2 protection, subsequently maintaining the high NH 3 -SCR performance and enhancing the SO 2 tolerance.
研究领域:
催化
·
环境科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
Catalysts
·
2021
·Vol. 11
·期 4
·445
·
IF 4.146
Yangyang Guo,Xiaofei Xu,Hong Gao,Yang Zheng,Lei Luo,Tingyu Zhu
Ca poisoning behavior is inevitable for high-calcium content flue gas, so V2O5-WO3/TiO2(VWT) and V2O5-WO3-CeO2/TiO2(VWCeT) catalysts with different vanadium content have been prepared and the Ca-doped catalysts are compared in this manuscript. The result shows Ce addition can both promote the NO conversion and the alkali resistance. Lower Ca addition for 0.1VWCeT catalyst promotes its oxidability and Ce modification is more suitable for low vanadium catalysts. The total acidity and the reducibility of catalysts decline after Ca doping, and the reducibility of the active species on catalysts has been strengthened by Ce addition. CeO2based catalysts with lower Ca loading struggle to resist sulfur poisoning, while higher Ca loading favors SO2adsorption and also physically reduces the cerium acidification process. In the presence of SO2, additional Brønsted acid sites are formed in Ca rich catalyst. The dynamic NH3adsorption has been investigated, shows that Ca doping content on catalyst is critical for SCR reaction, and the catalyst is more susceptible to SO2initially in alkali flue gas during the actual application, but the sulfur resistance may increase with the alkali-poisoning effect aggravated by Ca doping.Keywords:Ca-poisoning;SCR reaction;NO reduction;V2O5-WO3/TiO2and V2O5-WO3-CeO2/TiO2catalysts;SO2and water;NO removal efficiency
研究领域:
环境科学
·
催化化学
✓ 已验证
DOI
高影响因子
Tungsten
·
2024
·
IF 5.6
Zhang Zhi-Qi,Yang Liu,Luo Wen,An Vladimir,Li Jing,Liu Bao-Dan
The design and synthesis of vanadium-based denitration catalysts with low-temperature activity pose significant challenges in the field of toxic gas catalysis. In this study, we have developed a novel approach to fabricate highly efficient V 2 O 5 -WO 3 /TiO 2 monolithic mesh catalysts for NO x reduction at low temperatures. First, TiO 2 nanosheets with strong adhesion and large surface area were grown on Ti mesh using plasma electrolytic oxidation technology and hydrothermal method. Then, super-small traces of WO 3 and V 2 O 5 active nano-species were subsequently deposited on TiO 2 nanosheets using the deposition–precipitation method. Compared to traditional ceramic-based V 2 O 5 -WO 3 /TiO 2 catalysts, our V 2 O 5 -WO 3 /TiO 2 monolithic mesh catalyst exhibits superior mechanical performance, excellent thermal conductivity, lower pressure drop, higher utilization of active components, and stronger synergistic effects. Significantly, the V 2 O 5 -WO 3 /TiO 2 monolithic mesh catalysts exhibited excellent low-temperature catalytic activity with 98% of NO x conversion at 220 ℃, and remarkable long-term SO 2 tolerance and water resistance in the selective catalytic reduction (SCR) of NO x with NH 3 . The SCR reaction of tiny V 2 O 5 and WO 3 active species supported on TiO 2 nanosheets directly demonstrated to follow the Eley–Rideal mechanism by in situ infrared spectra.
研究领域:
催化
·
环境科学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED SURFACE SCIENCE
·
2023
·
IF 6.7
Zhixiang Ren,Ao Li,Xinyu Lei,Zhengwei Yu,Guangying Wang,Hongliang Zhang,Huan Chen,Yin Wang,Hongming Long
As a mainstream moderate-high temperature (250–420 °C) particulate denitrification catalyst, V 2 O 5 -WO 3 /TiO 2 (VWT) is not applicable to low-temperature (60–150 °C) iron ore sintering flue gas after semi dry/wet desulfurization. In order to improve the NH 3 -deNO x performance of the VWT particle catalyst at low temperatures, a series of powder VWT denitrification catalysts doped with different content of RuO 2 (R-VWT) prepared by the wet co-impregnation method were researched, and found that the particulate catalyst service temperature (about 100 % NO conversion) is lowered from 225 °C (VWT) to below 175 °C by doping 0.5 % RuO 2 . In addition, a series of characterizations indicate that the doped RuO 2 enhances the redox performance of R-VWT and promotes the generation of more surface active intermediate monodentate nitrate, and accelerates the low-temperature surface SCR transient reaction rate.
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
Journal of Materials Chemistry A
·
2023
·Vol. 11
·期 45
·24644-24650
·
IF 11.9
Dongrun Xu,Weiye Qu,Junhong Liu,Junxiao Chen,Xue Fang,Liwei Chen,Zhen Ma,Xi Liu,Xingfu Tang,Yaxin Chen
Selective catalytic reduction (SCR) is the most effective technology to control NO emission using commercial V2O5–WO3/TiO2 catalysts, but the nature of active catalytic sites remains under debate. Here we provide evidence demonstrating that dinuclear vanadium–tungsten sites are the most active catalytic sites of conventional V2O5–WO3/TiO2 catalysts, inconsistent with a prevailing view that dimeric vanadium sites are the active sites. The dinuclear vanadium–tungsten sites have inherently stronger acidity than the dimeric vanadium sites, favoring NH3 adsorption. Meanwhile, the vanadium 3d electrons of the dinuclear vanadium–tungsten sites are richer than those of the dimeric vanadium sites, facilitating O2 activation in SCR. Hence, the dinuclear vanadium–tungsten sites have higher SCR activity than the dimeric vanadium sites under identical reaction conditions. This work settles a long dispute on the identification of active sites of conventional V2O5–WO3/TiO2 SCR catalysts, thus having implications for a unified explanation of disparate SCR reaction mechanisms and rational design of improved SCR catalysts.
研究领域:
催化化学
·
环境化学
·
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
HYDROMETALLURGY
·
2019
·
IF 3.465
Wenbo Lou,Yang Zhang,Shili Zheng,Ping Li,Ying Zhang,Yi Zhang,Bo Zhao,Zhefei Li,Wei Jin
China generates a large number of scrapped selective catalytic reduction (SCR) catalysts in the fossil fuel combustion plants every year. As a result, there is a giant quantity of 5 × 10 5 t scrapped V 2 O 5 -WO 3 /TiO 2 SCR catalyst annually worldwide, in which arsenic poisoning is a major cause of catalysts deactivation . In this study, a novel cleaner recovery process of alkaline-acid stepwise leaching was proposed for the high‑arsenic scrapped SCR catalysts to achieve excellent arsenic removal and structural reforming. It is found that arsenic can be completely removed from 1.92% to below the detection limit, and the surface area of regenerated catalysts is restored to 31 m 2 /g (similar to that of commercial catalysts). In the subsequent pickling and regeneration, Na + can be eliminated to obtain anatase-type TiO 2 for further activity recovery. Besides, valuable elements (W, V) have been successfully recycled by leaching the As-containing solid waste with ammonium salt. After replenishing active components, regenerated catalyst exhibits comparable activity with the commercial fresh catalyst, offering a promising method for scrapped catalyst recovery and further understanding of cleaner produces for waste management .
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
危险品化学品经营许可证（带存储）