Denitration Performance of SnOx-CeOx/Pitch-Based Spherical Activated Carbon Catalysts for Selective Catalytic Reduction of NO
-
摘要: 以高软化点石油沥青原料制备的沥青基球形活性炭（PSAC）为载体，采用浸渍法负载锡、铈氧化物制备SnOx-CeOx/PSAC系列催化剂，考察催化剂在低温下的脱硝性能，并采用N2吸附/脱附、X射线衍射（XRD）、X射线光电子能谱（XPS）等方法对催化剂进行表征。结果表明，在CeOx/PSAC催化剂中添加SnOx后催化剂的脱硝活性显著增加，但随着金属担载量（质量分数）增加，脱硝活性呈现先升高后降低的趋势，Sn、Ce担载量分别为5%和13%的SnOx-CeOx/PSAC（以Sn(5%)Ce(13%)/PSAC表示）催化剂具有最高的脱硝活性，在该催化剂条件下，100~300 ℃时可得到最高的NO转化率（98%）。添加SnOx后，CeO2在载体表面的分散性得到提高，由于Sn4+替代Ce4+掺杂于立方相CeO2晶格中形成固溶体，因而催化剂的脱硝活性提高。此外，与单组分铈催化剂相比，Sn(5%)Ce(13%)/PSAC催化剂具有较好的抗SO2毒化性能。Abstract: Pitch-based spherical activated carbon (PSAC) is widely used in biomedicine, environmental protection and other practical fields because of its advantages of high specific surface area, high mechanical strength, high packing intensity and low fluid resistance. In this study, series of SnOx-CeOx/PSAC catalysts were prepared by the impregnation method using PSAC prepared from high softening point petroleum pitch as the support. Their catalytic performances were evaluated in the low-temperature selective catalytic reduction (SCR) of NO with NH3. The catalysts obtained were characterized by nitrogen adsorption/desorption, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The results show that SnOx-CeOx/PSAC catalyst exhibits higher SCR activity than CeOx/PSAC catalyst, and the NO conversion rate first increases and then decreases with the increase of metal loading. The Sn(5%)Ce(13%)/PSAC catalyst exhibits the highest NO removal activity, and the highest NO conversion rate reaches 98% in the temperature range of 100~300 ℃. This is mainly due to the improved dispersion of cerium oxide on the surface of PSAC in the presence of SnOx, and the formation of a solid solution between SnOx and CeOx with a fluorite-type structure probably caused by the incorporation of Sn4+ into the crystal lattice of CeO2. Furthermore, a certain amount of Ce3+ and a high percentage of chemisorbed oxygen exist on the catalyst surface because of the synergistic effect between tin and cerium oxides. These factors result in the excellent NH3-SCR performance of the Sn(5%)Ce(13%)/PSAC catalyst. Compared with CeOx/PSAC catalyst, SnOx-CeOx/PSAC catalyst exhibits a higher resistance to SO2 poisoning. The NO conversion rate of the Sn(5%)Ce(13%)/PSAC catalyst retains at 80% at 260 ℃ after the introduction of SO2 in the feed gas for 420 min.
-
图 2 PSAC的N2吸附/脱附等温线（a）和孔径分布曲线（b）
Figure 2. N2 adsorption/desorption isotherms (a) and corresponding pore size distribution curves (b) of PSAC
图 3 不同催化剂的脱硝活性比较
Figure 3. Comparison of denitration activities over various catalysts
图 4 不同金属担载量时SnOx-CeOx/PSAC催化剂的脱硝活性比较
Figure 4. Comparison of denitration activities over SnOx-CeOx/PSAC catalysts with different metal loadings
图 5 260 ℃下SO2对Sn(5%)Ce(13%)/PSAC和Ce/PSAC催化剂脱硝活性的影响
Figure 5. Effect of SO2 on denitration activities over Sn(5%)Ce(13%)/PSAC and Ce/PSAC catalysts at 260 ℃
图 6 不同金属担载量时SnOx-CeOx/PSAC催化剂的N2吸附/脱附等温线（a）和孔径分布曲线（b）
Figure 6. N2 adsorption/desorption isotherms (a) and corresponding pore size distribution curves (b) of SnOx-CeOx/PSAC catalysts with different metal loadings
图 8 Sn(5%)Ce(13%)/PSAC催化剂的XPS全谱图
Figure 8. XPS full spectrum of Sn(5%)Ce(13%)/PSAC catalyst
图 9 Sn(5%)Ce(13%)/PSAC催化剂的C 1s，O 1s，Ce 3d和Sn 3d的XPS分峰谱图
Figure 9. XPS spectra of C 1s, O 1s, Ce 3d and Sn 3d for Sn(5%)Ce(13%)/PSAC catalyst
表 1 PSAC的孔结构参数
Table 1. Pore structure parameters of PSAC
SBET/(m2·g−1) Smic/(m2·g−1) Vtotal/(cm3·g−1) Vmic/(cm3·g−1) 1522 1373 0.66 0.60 SBET—BET specific surface area; Smic—Micropore surface area; Vtotal—Total pore volume; Vmic—Micropore volume 
下载: 导出CSV
表 2 不同催化剂的BET比表面积和孔结构
Table 2. BET specific surface area and pore structure of various catalysts
Sample SBET/
(m2·g−1)Smic/
(m2·g−1)Vtotal/
(cm3·g−1)Vmic/
(cm3·g−1)Sn(1%)Ce(3%)/PSAC 926 861 0.36 0.35 Sn(3%)Ce(8%)/PSAC 754 668 0.35 0.28 Sn(5%)Ce(13%)/PSAC 684 624 0.31 0.26 Sn(7%)Ce(18%)/PSAC 513 452 0.24 0.19
下载: 导出CSV
表 3 Sn(5%)Ce(13%)/PSAC催化剂的表面原子摩尔分数
Table 3. Surface atomic mole fraction of Sn(5%)Ce(13%)/PSAC catalyst
Mole fraction/% Relative atomic ratio/%1) Sn C Ce O Oβ Oα 1.08 82.92 1.96 14.04 78.7 21.3 1) Calculated by the peak area
下载: 导出CSV
-
[1] BOSCH H, JANSSEN F. Formation and control of nitrogen oxides[J]. Catalysis Today, 1988, 2(4): 369-379. doi: 10.1016/0920-5861(88)80002-6 [2] BUSCA G, LIETTI L, RAMIS G, et al. Chemical and mechanistic aspects of the selective catalytic reduction of NOx by ammonia over oxide catalysts: A review[J]. Applied Catalysis B:Environmental, 1998, 18(1/2): 1-36. doi: 10.1016/S0926-3373(98)00040-X [3] YANG M, LIU Q C, XUE Q, et al. Preparation and characterization of V2O5-WO3/TiO2 catalyst by chemical vapor deposition[J]. Journal of Functional Materials, 2010, 41(4): 683-686. [4] KRISTENSEN S B, KUNOV-KRUSE A J, RIISAGER A, et al. High performance vanadia-anatase nanoparticle catalysts for the selective catalytic reduction of NO by ammonia[J]. Journal of Catalysis, 2011, 284(1): 60-67. doi: 10.1016/j.jcat.2011.08.017 [5] LIU Z M, ZHU J Z, LI J H, et al. Novel Mn-Ce-Ti mixed-oxide catalyst for the selective catalytic reduction of NOx with NH3[J]. ACS Applied Materials & Interfaces, 2014, 6(16): 14500-14508. [6] WANG Y L, HUANG Z G, LIU Z Y, et al. A novel activated carbon honeycomb catalyst for simultaneous SO2 and NO removal at low temperatures[J]. Carbon, 2004, 42(2): 445-448. doi: 10.1016/j.carbon.2003.11.006 [7] HUANG Z G, LIU Z Y, ZHANG X L, et al. Inhibition effect of H2O on V2O5/AC catalyst for catalytic reduction of NO with NH3 at low temperature[J]. Applied Catalysis B:Environmental, 2006, 63(3/4): 260-265. doi: 10.1016/j.apcatb.2005.10.011 [8] 王艳莉, 李翠, 詹亮, 等. 制备条件对蜂窝状MnOx/ACH催化剂低温脱硝性能的影响[J]. 华东理工大学学报(自然科学版), 2013, 39(5): 509-515. [9] WANG Y L, GE C Z, ZHAN L, et al. MnOx-CeO2/Activated carbon honeycomb catalyst for selective catalytic reduction of NO with NH3 at low temperature[J]. Industrial & Engineering Chemistry Research, 2012, 51(36): 11667-11673. [10] WANG X, ZHENG Y Y, Xu Z, et al. Low-temperature NO reduction with NH3 over Mn-CeOx/CNT catalysts prepared by a liquid-phase method[J]. Catalysis Science & Technology, 2014, 4(6): 1738-1741. [11] 唐晓龙, 郝吉明, 易红宏, 等. 活性炭改性整体催化剂上低温选择性还原NOx[J]. 中国环境科学, 2007, 27(6): 845-850. doi: 10.3321/j.issn:1000-6923.2007.06.026 [12] FANG C, SHI L Y, LI H R, et al. Creating hierarchically macro-/mesoporous Sn/CeO2 for the selective catalytic reduction of NO with NH3[J]. RSC Advances, 2016, 6(82): 78727-78736. doi: 10.1039/C6RA18339E [13] CHANG H Z, CHEN X Y, Li J H, et al. Improvement of activity and SO2 tolerance of Sn-modified CeO2-MnOx catalysts for NH3-SCR at low temperatures[J]. Environmental Science & Technology, 2013, 47(10): 5294-5301. [14] YU M, LI C T, ZENG G M, et al. The selective catalytic reduction of NO with NH3 over a novel Ce-Sn-Ti mixed oxides catalyst: Promotional effect of SnO2[J]. Applied Surface Science, 2015, 342: 174-182. doi: 10.1016/j.apsusc.2015.03.052 [15] WANG Y L, KANG Y, Ge M, et al. Cerium and tin oxides anchored onto reduced graphene oxide for selective catalytic reduction of NO with NH3 at low temperatures[J]. RSC Advances, 2018, 8(63): 36383-36391. doi: 10.1039/C8RA05151H [16] 刘朝军, 梁晓怿, 滕娜, 等. 气相氧化处理对沥青基球状活性炭表面化学及吸附性能的影响[J]. 新型炭材料, 2010, 25(6): 460-464. [17] WANG Z, WANG Y L, LONG D H, et al, Kinetics and mechanism study of low-temperature selective catalytic reduction of NO with urea supported on pitch-based spherical activated carbon[J]. Industrial & Engineering Chemistry Research, 2011, 50(10): 6017-6027. [18] 王际童, 刘小军, 李泽斯, 等. 沥青基球形活性炭对葡萄糖分子的吸附行为研究[J]. 离子交换与吸附, 2011, 27(3): 247-256. [19] LI X L, LI Y H, DENG S S, et al. A Ce-Sn-Ox catalyst for the selective catalytic reduction of NOx with NH3[J]. Catalysis Communications, 2013, 40: 47-50. doi: 10.1016/j.catcom.2013.05.024 [20] 王艳莉, 李晓晓, 詹亮, 等. 金属助剂对蜂窝状MnOx-CeO2/ACH催化剂低温脱硝行为的影响[J]. 燃料化学学报, 2014, 42(11): 1365-1371. doi: 10.3969/j.issn.0253-2409.2014.11.014 [21] WANG Y L, LI X X, ZHAN L, et al. Effect of SO2 on activated carbon honeycomb supported CeO2-MnOx catalyst for NO removal at low temperature[J]. Industrial & Engineering Chemistry Research, 2015, 54(8): 2274-2278. [22] 王艳莉, 何自国, 詹亮, 等. SnOx-CeO2-MnOx/球状活性炭催化剂低温选择性催化还原NO[J]. 新型炭材料, 2015, 30(6): 533-538. [23] CHEN Y Z, LIAW B J, HUANG C W. Selective oxidation of CO in excess hydrogen over CuO/CexSn1−xO2 catalysts[J]. Applied Catalysis A: General, 2006, 302(2): 168-176. doi: 10.1016/j.apcata.2005.12.032 [24] 纵宇浩, 沈岳松, 王玉云, 等. Ce-Sn-W-Ox催化剂的配伍优化及脱硝影响因素[J]. 环境工程学报, 2015, 9(3): 1329-1336. doi: 10.12030/j.cjee.20150357 [25] YAO W Q, CHEN J, ZHAN L, et al. Two-dimensional porous sandwich-like C/Si-graphene-Si/C nanosheets for superior lithium storage[J]. ACS Applied Materials & Interfaces, 2017, 9(45): 39371-39379. [26] TANG X, LI J, HAO J. Significant enhancement of catalytic activities of manganese oxide octahedral molecular sieve by marginal amount of doping vanadium[J]. Catalysis Communications, 2010, 11(10): 871-875. doi: 10.1016/j.catcom.2010.03.011 [27] LIU F, SHAN W, LIAN Z, et al. Novel MnWOx catalyst with remarkable performance for low temperature NH3-SCR of NOx[J]. Catalysis Science & Technology, 2013, 3(10): 2699-2707. [28] ZHANG G D, HAN W L, ZHAO H J, et al. Solvothermal synthesis of well-designed ceria-tin-titanium catalysts with enhanced catalytic performance for wide temperature NH3-SCR reaction[J]. Applied Catalysis B:Environmental, 2018, 226: 117-126. doi: 10.1016/j.apcatb.2017.12.030 [29] XU X L, ZHANG R B, ZENG X R, et al. Effects of La, Ce, and Y oxides on SnO2 catalysts for CO and CH4 oxidation[J]. ChemCatChem, 2013, 5(7): 2025-2036. [30] YAO X J, XIONG Y, ZOU W X, et al. Correlation between the physicochemical properties and catalytic performances of CexSn1−xO2 mixed oxides for NO reduction by CO[J]. Applied Catalysis B:Environmental, 2014, 144: 152-165. doi: 10.1016/j.apcatb.2013.06.020 [31] ZHANG L, LI L L, CAO Y, et al. Promotional effect of doping SnO2 into TiO2 over a CeO2/TiO2 catalyst for selective catalytic reduction of NO by NH3[J]. Catalysis Science& Technology, 2015, 5: 2188-2196. [32] 唐幸福, 李俊华, 魏丽斯, 等. 氧化还原沉淀法制备MnOx-SnO2催化剂及其对NO的NH3选择催化还原性能[J]. 催化学报, 2008, 29(6): 531-536. doi: 10.3321/j.issn:0253-9837.2008.06.007 -
点击查看大图
计量
- 文章访问数: 230
- HTML全文浏览量: 127
- PDF下载量: 134
- 被引次数: 0
