The Regulation of MoO x State and Its Effect on the Denitration Performance and Thermal Stability of VO x /MoO x ⁃TiO2 Catalysts

doi:10.12422/j.issn.1006-396X.2024.04.006

Abstract

Abstract:

Ammonium heptamolybdate was dissolved in water or oxalic acid solution,and then compounded with TiO₂ to prepare MoO _x ?TiO₂ support,and the VO _x /MoO _x ?TiO₂ catalysts were obtained after loading vanadium by impregnation method.The structure and properties of the catalysts were characterized by XRD,SEM,BET,XPS,H₂?TPR and NH₃?TPD,and its denitration activity and high temperature aging performance were investigated.The results showed that the denitrification efficiency of VMoTiO?F prepared by oxalic acid?assisted dissolution of (NH₄)₆Mo₇O₂₄ was greater than 80.0% at 210 ~ 510 °C,which was better than that of VMoTiH?F prepared by water dissolution.Because there was more MoO _x on the surface of VMoTiO?F,the interaction with VO _x was enhanced,which promoted the production of more low?valence VO _x and surface chemisorbed oxygen (O_α) active species on the surface of the catalyst.At the same time,the interaction between VO _x and MoO _x could also improve the low?temperature redox performance and facilitate the electron transfer in the catalytic process.After high temperature aging,VMoTiH?F had more MoO _x into the TiO₂ lattice than VMoTiO?F,which was helpful to improve the thermal stability of TiO₂.However, anatase TiO₂ in VMoTiO?A was seriously sintered or even partially transformed into inert rutile crystal during high temperature aging,resulting in the loss of surface acid sites and the reduction of redox properties.Therefore,the denitrification performance of VMoTiH?A catalyst was significantly higher than that of VMoTiO?A.

Key words: VO _x /MoO _x ?TiO₂, NH₃?SCR, MoO _x ?TiO₂ composite support, Active component VO _x, Thermal stability

摘要：

将七钼酸铵分别用水和草酸溶液溶解后与TiO₂复合制备MoO _x ?TiO₂载体，通过浸渍法负载钒获得VO _x /MoO _x ?TiO₂催化剂；采用XRD、SEM、BET、XPS、H₂?TPR和NH₃?TPD表征手段研究催化剂的结构和性质，并考察了其脱硝活性和高温老化性能。结果表明，草酸助溶七钼酸铵制得的VMoTiO?F在210~510 ℃的脱硝效率大于80.0%，优于用水溶解制备的VMoTiH?F；VMoTiO?F表面存在较多的MoO _x，可增强与VO _x 的相互作用，促进催化剂表面产生更多的低价态VO _x 和表面化学吸附氧(O_α)活性物种；VMoTiO?F中的VO _x 和MoO _x 相互作用还能提高低温氧化还原性能，有利于催化过程中的电子传递；VMoTiH?F相比VMoTiO?F有更多的MoO _x 进入TiO₂晶格，提高TiO₂的热稳定性，而VMoTiO?A中的锐钛矿TiO₂在高温老化中被严重烧结甚至部分转变为惰性金红石晶型，导致表面酸性位损失和氧化还原性能降低，因此VMoTiH?A催化剂的脱硝性能明显优于VMoTiO?A。

关键词: VO _x /MoO _x ?TiO₂, 氨选择性催化还原, MoO _x ?TiO₂复合载体, 活性VO _x, 热稳定性

CLC Number:

TQ032.4

Ping FANG, Kangxin CHEN, Yuting LIN, Kaihao FAN, Chengyu SHAN, Xuesong LIU. The Regulation of MoO _x State and Its Effect on the Denitration Performance and Thermal Stability of VO _x /MoO _x ⁃TiO₂ Catalysts[J]. Journal of Petrochemical Universities, 2024, 37(4): 40-48.

方萍, 陈康欣, 林雨婷, 范楷浩, 单承宇, 刘雪松. MoO _x 状态调控及其对VO _x /MoO _x ⁃TiO₂催化剂脱硝性能和热稳定性的影响[J]. 石油化工高等学校学报, 2024, 37(4): 40-48.

Figures/Tables 11

Fig.1 NH3?SCR activity diagram of catalysts

Fig.2 XRD patterns of the catalysts

Table 1 Phase composition,particle size,cell volume and SBET of the catalyst

催化剂	w/%		晶粒尺寸^*/nm		晶胞体积/ nm³	粒径分布范围^**/nm	S_BET /（m² $⋅$ g^-1）
催化剂	锐钛矿型TiO₂	金红石TiO₂	锐钛矿TiO₂	金红石TiO₂	晶胞体积/ nm³	粒径分布范围^**/nm	S_BET /（m² $⋅$ g^-1）
VMoTiH⁃F	100.0	-	17.5	-	0.135 67	10~30	67.49
VMoTiO⁃F	100.0	-	26.4	-	0.136 17	20~45	49.32
VMoTiH⁃A	100.0	-	31.9	-	0.135 85	26~60	44.15
VMoTiO⁃A	95.0	5.0	103.1	160.4	0.136 12	80~170	10.25

Table 1 Phase composition,particle size,cell volume and SBET of the catalyst

催化剂	w/%		晶粒尺寸^*/nm		晶胞体积/ nm³	粒径分布范围^**/nm	S_BET /（m² $⋅$ g^-1）
催化剂	锐钛矿型TiO₂	金红石TiO₂	锐钛矿TiO₂	金红石TiO₂	晶胞体积/ nm³	粒径分布范围^**/nm	S_BET /（m² $⋅$ g^-1）
VMoTiH⁃F	100.0	-	17.5	-	0.135 67	10~30	67.49
VMoTiO⁃F	100.0	-	26.4	-	0.136 17	20~45	49.32
VMoTiH⁃A	100.0	-	31.9	-	0.135 85	26~60	44.15
VMoTiO⁃A	95.0	5.0	103.1	160.4	0.136 12	80~170	10.25

Fig.3 SEM images of the catalysts

Fig.4 The adsorption and desorption curves and pore size distribution of the catalysts

Fig.5 XPS spectra of the catalysts

Table 2 The relative concentration of each element on the catalyst surface and the proportion of atomic concentration of different valence states

催化剂	A(V³⁺+V⁴⁺)/ A(V_总)	A（Mo⁵⁺）/ A(Mo⁵⁺+Mo⁶⁺)	A（O_α）/A（O $α,$ +O_α+O_β）	A（V）/A（Ti）	A（Mo）/A（Ti）
VMoTiH⁃F	0.615 7	0.197 1	0.229 9	0.074 2	0.052 1
VMoTiO⁃F	0.796 3	0.142 7	0.323 3	0.064 6	0.062 5
VMoTiH⁃A	0.584 8	0.284 0	0.222 4	0.059 9	0.075 5
VMoTiO⁃A	0.466 6	0.325 8	0.175 7	0.014 0	0.015 0

Table 2 The relative concentration of each element on the catalyst surface and the proportion of atomic concentration of different valence states

催化剂	A(V³⁺+V⁴⁺)/ A(V_总)	A（Mo⁵⁺）/ A(Mo⁵⁺+Mo⁶⁺)	A（O_α）/A（O $α,$ +O_α+O_β）	A（V）/A（Ti）	A（Mo）/A（Ti）
VMoTiH⁃F	0.615 7	0.197 1	0.229 9	0.074 2	0.052 1
VMoTiO⁃F	0.796 3	0.142 7	0.323 3	0.064 6	0.062 5
VMoTiH⁃A	0.584 8	0.284 0	0.222 4	0.059 9	0.075 5
VMoTiO⁃A	0.466 6	0.325 8	0.175 7	0.014 0	0.015 0

Fig.6 The H2?TPR profiles of the catalysts

Table 3 Amounts of H2 consumption from the H2?TPR results

催化剂	还原峰温度/°C			H₂消耗量/（μmol $⋅$ g^-1）			H₂总消耗量/ （μmol $⋅$ g^-1）
催化剂	低温峰	中温峰	高温峰	低温峰	中温峰	高温峰	H₂总消耗量/ （μmol $⋅$ g^-1）
VMoTiH⁃F	542/587	—	813	353.5/297.6	—	2.9	654.0
VMoTiO⁃F	503/564	633	790	84.4/371.7	66.6	47.9	570.6
VMoTiH⁃A	546/596	—	—	101.9/141.4	—	—	243.3
VMoTiO⁃A	585	660	—	44.6	118.0	—	162.6

Table 3 Amounts of H2 consumption from the H2?TPR results

催化剂	还原峰温度/°C			H₂消耗量/（μmol $⋅$ g^-1）			H₂总消耗量/ （μmol $⋅$ g^-1）
催化剂	低温峰	中温峰	高温峰	低温峰	中温峰	高温峰	H₂总消耗量/ （μmol $⋅$ g^-1）
VMoTiH⁃F	542/587	—	813	353.5/297.6	—	2.9	654.0
VMoTiO⁃F	503/564	633	790	84.4/371.7	66.6	47.9	570.6
VMoTiH⁃A	546/596	—	—	101.9/141.4	—	—	243.3
VMoTiO⁃A	585	660	—	44.6	118.0	—	162.6

Fig.7 NH3?TPD profiles of the catalysts

Table 4 The NH3 desorption calculated from the NH3?TPD results

催化剂	还原峰温度/°C			NH₃脱附量/（μmol·g^-1）			NH₃脱附总量/ （μmol·g^-1）
催化剂	低温峰	中温峰	高温峰	低温峰	中温峰	高温峰	NH₃脱附总量/ （μmol·g^-1）
VMoTiH⁃F	133	221	356	22.99	67.57	45.20	135.76
VMoTiO⁃F	121	195	338	15.52	49.89	30.38	95.79
VMoTiH⁃A	101	156	232	8.91	15.48	17.71	42.10
VMoTiO⁃A	121	195	—	4.17	12.32	—	16.49

References 22

1	王献忠，吴彦霞，梁海龙，等.V₂O₅⁃MoO₃/TiO₂催化剂脱硝性能的研究［J］.石油炼制与化工，2021，52（1）：79⁃85.
	WANG X Z，WU Y X，LIANG H L，et al.Research of denitration performance of V₂O₅⁃MoO₃/TiO₂ catalyst［J］.Petroleum Processing and Petrochemicals，2021，52（1）：79⁃85.
2	宋坤，陈海平，张娜，等.选择性催化还原脱硝系统结构数值模拟与优化［J］.低碳化学与化工，2023，48（2）：105⁃112.
	SONG K，CHEN H P，ZHANG N，et al.Numerical simulation and optimization of structure of selective catalytic reduction denitriifcation system［J］.Low⁃Carbon Chemistry and Chemical Engineering，2023，48（2）：105⁃112.
3	LIU X S，WU X D，XU T F，et al.Effects of silica additive on the NH₃⁃SCR activity and thermal stability of a V₂O₅/WO₃⁃TiO₂ catalyst［J］.Chinese Journal of Catalysis，2016，37（8）：1340⁃1346.
4	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.
5	彭富昌.钒系脱硝催化剂的研究现状及发展趋势［J］.当代化工，2013，42（11）：1562⁃1564.
	PENG F C.Research status and prospect of vanadium catalysts for De⁃NOx［J］.Contemporary Chemical Industry，2013，42（11）：1562⁃1564.
6	赵博，随志明，李浙飞，等.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.
	ZHAO B，SUI Z M，LI Z F，et al.Effects of S，P，Si doping on the evolution of active species and NH₃⁃SCR activity of a VOx/TiO₂ catalyst［J］.Journal of Petrochemical Universities，2021，34（5）：16⁃23.
7	CASAGRANDE L，LIETTI L，NOVA I，et al.SCR of NO by NH₃ over TiO₂⁃supported V₂O₅⁃MoO₃ catalysts：Reactivity and redox behavior［J］.Applied Catalysis B：Environmental，1999，22（1）：63⁃77.
8	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.
9	ZHANG S L，ZHONG Q.Promotional effect of WO₃ on O 2 - over V₂O₅/TiO₂ catalyst for selective catalytic reduction of NO with NH₃［J］.Journal of Molecular Catalysis A：Chemical，2013，373：108⁃113.
10	JIA Y，ZHANG S，DAI B，et al.Preparation of low⁃temperature DeNOx catalyst of supported vanadium phosphate and its resistance to sulfur dioxide and water vapor［J］.Chinese Journal of Environmental Engineering，2019，13（1）：125⁃133.
11	WU Y X，LIANG H L，CHEN X，et al.Effect of preparation methods on denitration performance of V⁃Mo/TiO₂ catalyst［J］.Journal of Fuel Chemistry and Technology，2020，48（2）：189⁃196.
12	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.
13	GAO Y，WU X D，RAN R，et al.Effects of MoOx on dispersion of vanadia and low⁃temperature NH₃⁃SCR activity of titania supported catalysts：Liquid acidity and steric hindrance［J］.Applied Surface Science，2022，585：152710.
14	QING M X，SU S，WANG L L，et al.Getting insight into the oxidation of SO₂ to SO₃ over V₂O₅⁃WO₃/TiO₂ catalysts：Reaction mechanism and effects of NO and NH₃［J］.Chemical Engineering Journal，2019，361：1215⁃1224.
15	WU R，LI L C，ZHANG N Q，et al.Enhancement of low⁃temperature NH₃⁃SCR catalytic activity and H₂O & SO₂ resistance over commercial V₂O₅⁃MoO₃/TiO₂ catalyst by high shear⁃induced doping of expanded graphite［J］.Catalysis Today，2021，376：302⁃310.
16	JIANG Y，BAO C Z，LIU Q Y，et al.A novel CeO₂⁃MoO₃⁃WO₃/TiO₂ catalyst for selective catalytic reduction of NO with NH₃［J］.Catalysis Communications，2018，103：96⁃100.
17	黄力，王虎，纵宇浩，等.助剂Ga对V₂O₅⁃MoO₃/TiO₂催化剂脱硝性能的影响［J］.化工环保，2020，40（2）：198⁃202.
	HUANG L，WANG H，ZONG Y H，et al.Effect of gallium as additive on denitration capability of V₂O₅⁃MoO₃/TiO₂ catalyst［J］.Environmental Protection of Chemical Industry，2020，40（2）：198⁃202.
18	岳彦伟，黄力，王素芹，等.煅烧气氛对高V₂O₅含量V₂O₅⁃MoO₃/TiO₂脱硝催化剂性能的影响［J］.化工环保，2024，44（2）：257⁃264.
	YUE Y W，HUANG L，WANG S Q，et al.Effect of calcination atmosphere on performance of V₂O₅⁃MoO₃/TiO₂ denitration catalyst with high V₂O₅ content［J］.Environmental Protection of Chemical Industry，2024，44（2）：257⁃264.
19	GU HEO J，ULLAH M，CHUN M P，et al.Low⁃temperature shift DeNOx activity of nanoflake V₂O₅ loaded WO₃/TiO₂ as NH₃⁃SCR catalyst［J］.Inorganic Chemistry Communications，2022，137：109191.
20	沈伯雄，马娟.SiO₂改性的V₂O₅⁃MoO₃/TiO₂催化剂抗碱中毒性能研究［J］.燃料化学学报，2012，40（2）：247⁃251.
	SHEN B X，MA J.Alkali⁃resistant performance of V₂O₅⁃MoO₃/TiO₂ catalyst modified by SiO₂［J］.Journal of Fuel Chemistry and Technology，2012，40（2）：247⁃251.
21	HE S X，ZHAO R，PAN D M，et al.Low temperature reaction mechanism of NH₃⁃SCR reaction on MoOx modified CePO₄ catalyst：Combination study on experiments and DFT calculations［J］.Fuel，2024，360：130494.
22	蒋鹏，王阳慧，陈勇，等.CeO₂⁃WO₃/TiO₂催化剂中Ce⁃W相互作用对NH₃⁃SCR反应性能的影响［J］.中国稀土学报，2024，42（2）：226⁃235.
	JIANG P，WANG Y H，CHEN Y，et al.Synergistic effect of Ce⁃W in CeO₂⁃WO₃/TiO₂ catalyst on performance of NH₃⁃SCR reaction［J］.Journal of the Chinese Society of Rare Earths，2024，42（2）：226⁃235.

[1]	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.
[2]	Tian Sha,Li Huipeng,Zhao Hua,et al. Synthesis and Characterization of Y/MCM41 Composite Molecular Sieve [J]. Journal of Petrochemical Universities, 2015, 28(6): 20-24.
[3]	Hu Weiqing, Wu Libao, Huang Wanli, Luo Wangqun. Preparation and Application Evaluation of High Thermal Stability Insoluble Sulfur [J]. Journal of Petrochemical Universities, 2015, 28(4): 18-21.
[4]	JIANG Hai-ying, Lv Zhen-bo, LIU Dan, et al. The Study of H₃PO₄ and HZSM-5 by the Density Functional Theory [J]. Journal of Petrochemical Universities, 2011, 24(6): 54-58.

The Regulation of MoO _x State and Its Effect on the Denitration Performance and Thermal Stability of VO _x /MoO _x ⁃TiO₂ Catalysts

MoO _x 状态调控及其对VO _x /MoO _x ⁃TiO₂催化剂脱硝性能和热稳定性的影响

HTML

PDF

Knowledge

Abstract

Cite this article

share this article

Figures/Tables 11

References 22

Related Articles 4

Recommended Articles

Metrics