Effects of S, P, Si Doping on the Evolution of Active Species and NH3⁃SCR Activity of a VOx/TiO2 Catalyst

doi:10.3969/j.issn.1006-396X.2021.05.003

Abstract

Abstract:

A series of S, P, Si?doped TiO₂ supports and the corresponding VO_x/TiO₂ catalysts were prepared by sol?gel method and impregnation method for the purpose of enhancing SCR performance.Among them,the S?doped VO_x/TiO₂ catalyst exhibited the best low and medium temperature SCR performance and the widest active temperature window.According to the results of various analyses,the doping greatly influenced the agglomeration of vanadium species.As a result, numerous active polymeric VO_xspecies were emerged on the surface of catalysts.Meanwhile,S and Si was doped into TiO₂ lattice via the replacement of Ti⁴⁺ by S⁴⁺ and Si⁴⁺ to generate Ti-O-S and Ti-O-Si bonds,along with producing more surface V⁴⁺+V³⁺ and more chemisorbed oxygen species.The synergistic effect of the two active species can promote the oxidation of NO to NO₂,which can participate in the fast?SCR reaction by accelerating the reoxidation of VO_x species in the Redox process,and then improve the SCR performance of VO_x/TiO₂ catalyst at low and medium temperature range.The redox ability and activity of P?doped VO_x/TiO₂ catalyst are relatively low,because more phosphate is produced in the catalyst.Although doping S,P and Si has a significant effect on the acidity of the catalyst,it is not the dominate factor to determine the SCR activity.

Key words: Doping, VO_x/TiO₂ catalyst, Vanadium species, Active oxygen species, NH₃?SCR

摘要：

依次采用溶胶?凝胶法和浸渍法制备了一系列S、P、Si掺杂的TiO₂载体和相应的VO_x/TiO₂催化剂，以提高催化剂的SCR性能。其中，S掺杂的VO_x/TiO₂催化剂具有最佳的中低温SCR性能和最宽的工作温度窗口。根据各种表征分析结果可知，掺杂元素通过促进VO_x团聚生成具有较高的SCR反应活性的聚合态VO_x；而S⁴⁺和Si⁴⁺取代TiO₂中的Ti⁴⁺生成了Ti-O-S和Ti-O-Si键，这使催化剂中产生了更多的低价态V(V⁴⁺+V³⁺)和表面化学吸附氧。两者协同作用可促进NO氧化生成NO₂，产生的NO₂可通过加速VO_x物种在Redox过程中的重氧化来参与快速SCR反应，进而提升VO_x/TiO₂催化剂的中低温脱硝性能。由于P掺杂的VO_x/TiO₂催化剂中产生了较多的磷酸盐，从而导致其氧化还原性能和中低温活性相对较低。S、P、Si掺杂虽然对催化剂的酸性性能产生了显著的影响，但这并不是影响催化剂SCR活性的决定性因素。

关键词: 掺杂, VO_x/TiO₂催化剂, 钒物种, 活性氧物种, NH₃?SCR

CLC Number:

O643.32

Bo Zhao, Zhiming Sui, Zhefei Li, Wanying Huo, Kuo Wang, Gangfeng Shen, Xuesong Liu. Effects of S, P, Si Doping on the Evolution of Active Species and NH₃⁃SCR Activity of a VO_x/TiO₂ Catalyst[J]. Journal of Petrochemical Universities, 2021, 34(5): 16-23.

赵博, 随志明, 李浙飞, 霍婉莹, 王阔, 沈刚峰, 刘雪松. S、P、Si掺杂对钒钛催化剂活性物种状态调控及脱硝性能影响[J]. 石油化工高等学校学报, 2021, 34(5): 16-23.

Figures/Tables 11

Fig. 1 NOx conversion and N2 selectivity and NO oxidation curves of the VOx/TiO2 catalysts

Fig. 2 XRD patterns of the supports and catalysts

Table 1 Crystallite size, SBET, average pore diameter and pore volume of the supports and catalysts

载体及催化剂	晶粒尺寸/nm	晶胞体积/nm³	比表面积/（ $m 2$ $⋅$ g^-1）	平均孔径/nm	孔容/（ $c m 3$ ·g^-1）
V/Ti	21.4	0.136 1	39.08	21.2	0.17
V/Ti⁃S	18.8	0.135 6	44.92	24.5	0.24
V/Ti⁃P	14.2	0.135 8	78.88	14.1	0.27
V/Ti⁃Si	20.1	0.135 7	59.14	17.9	0.25
TiO₂	19.9	0.136 2	41.33	19.6	0.18
TiO₂⁃S	18.4	0.135 7	54.03	18.1	0.26
TiO₂⁃P	13.6	0.135 9	93.48	12.8	0.30
TiO₂⁃Si	16.5	0.135 8	59.33	17.4	0.25

Table 1 Crystallite size, SBET, average pore diameter and pore volume of the supports and catalysts

载体及催化剂	晶粒尺寸/nm	晶胞体积/nm³	比表面积/（ $m 2$ $⋅$ g^-1）	平均孔径/nm	孔容/（ $c m 3$ ·g^-1）
V/Ti	21.4	0.136 1	39.08	21.2	0.17
V/Ti⁃S	18.8	0.135 6	44.92	24.5	0.24
V/Ti⁃P	14.2	0.135 8	78.88	14.1	0.27
V/Ti⁃Si	20.1	0.135 7	59.14	17.9	0.25
TiO₂	19.9	0.136 2	41.33	19.6	0.18
TiO₂⁃S	18.4	0.135 7	54.03	18.1	0.26
TiO₂⁃P	13.6	0.135 9	93.48	12.8	0.30
TiO₂⁃Si	16.5	0.135 8	59.33	17.4	0.25

Fig.3 SEM images of catalysts

Fig. 4 XPS spectra of catalysts: V 2p, Ti 2p , O 1s and S 2p

Table 2 Atomic ratios obtained by different characterization methods

催化剂	表面原子浓度比/%
催化剂	（V/Ti）^a	（V/Ti）^b	（Ad/Ti）^a	（Ad/Ti）^b
V/Ti	0.040	0.009	-	-
V/Ti⁃S	0.032	0.009	0.070	0.008
V/Ti⁃P	0.021	0.009	0.081	0.008
V/Ti⁃Si	0.033	0.009	0.074	0.008

Fig. 5 Raman spectra of the catalysts in the ranges of 925~1 090 cm-1

Fig. 6 H2?TPR profiles of the catalysts

Fig. 7 NH3?TPD profiles of the catalysts

Table 3 Amounts of H2 consumption and NH3?TPD on the catalysts from the H2?TPR and NH3?TPD curves

催化剂	H₂消耗量/（μmol $⋅$ g^-1）				NH₃脱附量/（μmol $⋅$ g^-1）
催化剂	低温峰	中温峰	高温峰	总量	低温峰	中温峰	高温峰	总量
V/Ti	201	-	-	201	6.11	20.37	26.22	52.70
V/Ti⁃S	242	257	97	596	7.76	28.11	28.46	64.33
V/Ti⁃P	359	103	167	629	26.69	28.55	21.58	76.82
V/Ti⁃Si	212	-	-	212	6.94	8.64	25.68	41.26

Table 3 Amounts of H2 consumption and NH3?TPD on the catalysts from the H2?TPR and NH3?TPD curves

催化剂	H₂消耗量/（μmol $⋅$ g^-1）				NH₃脱附量/（μmol $⋅$ g^-1）
催化剂	低温峰	中温峰	高温峰	总量	低温峰	中温峰	高温峰	总量
V/Ti	201	-	-	201	6.11	20.37	26.22	52.70
V/Ti⁃S	242	257	97	596	7.76	28.11	28.46	64.33
V/Ti⁃P	359	103	167	629	26.69	28.55	21.58	76.82
V/Ti⁃Si	212	-	-	212	6.94	8.64	25.68	41.26

Fig. 8 Mechanism of S, P and Si doping to improve SCR activity in V/Ti catalyst at low temperature

References 27

1	王铮. 商业钒钛基SCR脱硝催化剂的改性研究［J］.化工管理， 2020 （34）： 139⁃140.
	Wang Z.Research on modification of commercial vanadium titanium based SCR catalyst［J］.Chemical Enterprise Management， 2020 （34）： 139⁃140.
2	He G Z， Lian Z H， Yu Y B， et al. Polymeric vanadyl species determine the low⁃temperature activity of V⁃based catalysts for the SCR of NOx with NH₃［J］. Science Advances， 2018， 4： 4637.
3	Chen H F， Xia Y， Fang R Y， et al. The effects of tungsten and hydrothermal aging in promoting NH₃⁃SCR activity on V₂O₅/WO₃⁃TiO₂ catalysts［J］. Applied Surface Science， 2018， 459： 639⁃646.
4	Zhao W， Zhong Q， Pan Y X， et al. Defect structure and evolution mechanism of O₂ radical in F⁃doped V₂O₅/TiO₂ catalysts［J］. Colloids and Surfaces A： Physicochemical and Engineering Aspects， 2013， 436： 1013⁃1020.
5	Zhao W， Zhong Q， Pan Y X， et al. Systematic effects of S⁃doping on the activity of V₂O₅/TiO₂ catalyst for low⁃temperature NH₃⁃SCR［J］. Chemical Engineering Journal， 2013， 228： 815⁃823.
6	刘庆航，晏乃强，翟赞，等. 溴掺杂钒钛催化剂SCR反应动力学研究［J］. 高等化学工程学报， 2017， 31（5）： 1193⁃1200.
	Liu Q H， Yan N Q， Qu Z，et al.Kinetic study on selective catalytic reduction of NOx by Br⁃doped V₂O₅/TiO₂catalysts［J］.Journal of Chemical Engineering of Chinese Universities， 2017， 31（5）： 1193⁃1200.
7	Shi A J， Wang X Q， Yu T， et al. The effect of zirconia additive on the activity and structure stability of V₂O₅/WO₃⁃TiO₂ ammonia SCR catalysts［J］. Applied Catalysis B： Environmental， 2011， 106： 359⁃369.
8	Wang X M， Du X S， Yang G P， et al. Chemisorption of NO₂ on V⁃Based SCR Catalysts： A fundamental study toward the mechanism of "Fast SCR" reaction［J］. The Journal of Physical Chemistry C， 2019， 123： 20451⁃20458.
9	Marberger A， Ferri D， Rentsch D， et al. Effect of SiO₂ on co⁃impregnated V₂O₅/WO₃/TiO₂ catalysts for the selective catalytic reduction of NO with NH₃［J］. Catalysis Today， 2019， 320： 123⁃132.
10	Yang B， Zhou J B， Wang W W， et al. Extraction and separation of tungsten and vanadium from spent V₂O₅⁃WO₃/TiO₂ SCR catalysts and recovery of TiO₂ and sodium titanate nanorods as adsorbent for heavy metal ions［J］. Colloids and Surfaces A： Physicochemical and Engineering Aspects， 2020， 601： 124963.
11	Won J M， Kim M S， Hong S C. The cause of deactivation of VOx/TiO₂ catalyst by thermal effect and the role of tungsten addition［J］. Chemical Engineering Science， 2021， 229： 116068.
12	Zhang S L， Zhong Q. Promotional effect of WO₃ on O2- over V₂O₅/TiO₂ catalyst for selective catalytic reduction of NO with NH₃［J］. Journal of Molecular Catalysis A： Chemical， 2013， 373： 108⁃113.
13	Zhang S L， Zhong Q. Surface characterization studies on the interaction of V₂O₅⁃WO₃/TiO₂ catalyst for low temperature SCR of NO with NH₃［J］. Journal of Solid State Chemistry， 2015， 221： 49⁃56.
14	Li Q C， Chen S F， Liu Z Y， et al. Combined effect of KCl and SO₂ on the selective catalytic reduction of NO by NH₃ over V₂O₅/TiO₂ catalyst［J］. Applied Catalysis B： Environmental， 2015， 164： 475⁃482.
15	Qing M X， Su S， Qian K， et al. Insight into the catalytic performance and NH₃ adsorption under high concentration of CO₂ and/or H₂O conditions on selective catalytic reduction of NO by NH₃ over V₂O₅⁃WO₃/TiO₂ catalyst［J］. Fuel， 2021， 286： 119478.
16	Kwon D W， Lee S， Kim J， et al. Influence of support composition on enhancing the performance of Ce⁃V on TiO₂ comprised tungsten⁃silica for NH₃⁃SCR［J］. Catalysis Today， 2021， 359： 112⁃123.
17	Liu X S， Chen X Y. A visible light response TiO₂ photocatalyst realized by cationic S⁃doping and its application for phenol degradation［J］. Journal of Hazardous Materials， 2008， 152： 48⁃55.
18	Arfaoui J， Ghorbel A， Petitto C， et al. Novel V₂O₅⁃CeO₂⁃TiO₂⁃SO42- nanostructured aerogel catalyst for the low temperature selective catalytic reduction of NO by NH₃ in excess O₂［J］. Applied Catalysis B： Environmental， 2018， 224： 264⁃275.
19	Besselmann S， Loffler E， Muhler M， et al. On the role of monomeric vanadyl species in toluene adsorption and oxidation on V₂O₅/TiO₂ catalysts： A Raman and in situ DRIFTS study［J］. Journal of Molecular Catalysis A： Chemical， 2000， 162： 401⁃411.
20	Zhao W， Zhang K， Wu L C， et al. Ti³⁺ doped V₂O₅/TiO₂ catalyst for efficient selective catalytic reduction of NOx with NH₃［J］. Journal of Colloid and Interface Science， 2021， 581： 76⁃83.
21	Chen M Q， Hu J X， Wang Y S， et al. Hydrogen production from acetic acid steam reforming over Ti⁃modified Ni/Attapulgite catalysts［J］. International Journal of Hydrogen Energy， 2021， 46： 3651⁃3668.
22	Si W Z， Liu H Y， Yan T， et al. Sn⁃doped rutile TiO₂ for vanadyl catalysts： Improvements on activity and stability in SCR reaction［J］.Applied Catalysis B： Environmental， 2020， 269： 118797.
23	Cheng J， Song Y， Ye Q， et al. A mechanistic investigation on the selective catalytic reduction of NO with ammonia over the V⁃Ce/Ti⁃PILC catalysts［J］. Molecular Catalysis， 2018， 445： 111⁃123.
24	Li H L， Qiu L， Bharti B， et al. Efficient photocatalytic degradation of acrylonitrile by sulfur⁃bismuth co⁃doped F⁃TiO₂/SiO₂ nanopowder［J］. Chemosphere， 2020， 249： 126135.
25	Li H Y， Zhang S L， Zhong Q， et al. Effect of nitrogen doping on oxygen vacancies of titanium dioxide supported vanadium pentoxide for ammonia⁃SCR reaction at low temperature［J］. Journal of Colloid and Interface Science， 2013， 402： 190⁃195.
26	Li F K， Shen B X， Tian L H， et al. Enhancement of SCR activity and mechanical stability on cordierite supported V₂O₅⁃WO₃/TiO₂ catalyst by substrate acid pretreatment and addition of silica［J］. Powder Technology， 2016， 297： 384⁃391.
27	Wang X， Du X， Yang G， et al. Chemisorption of NO₂ on V⁃Based SCR catalysts： A fundamental study toward the mechanism of “Fast SCR” reaction［J］. The Journal of Physical Chemistry C，2019，123（33）：20451⁃20458.

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Effects of S, P, Si Doping on the Evolution of Active Species and NH₃⁃SCR Activity of a VO_x/TiO₂ Catalyst

S、P、Si掺杂对钒钛催化剂活性物种状态调控及脱硝性能影响

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References 27

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