Preparation of different morphologies of Au/α-MnO2 catalyst for oxidation of carbon monoxide and toluene
-
摘要: 以高锰酸钾和(或)硫酸锰为锰源,分别采用水热法和PVA保护的硼氢化钠还原法,制备了一维纳米棒状、线状和管状xAu/MnO2(x为2%、4%、8%和10%)催化剂。一维棒状、线状和管状xAu/MnO2中的MnO2均为四方晶相α-MnO2,其α-MnO2样品的比表面积为48.4~114.0 m 2/g。棒状4%Au/α-MnO2的催化活性最好:在空速为20 000 mL/(g·h)的条件下,CO转化率达到50%和90%时的反应温度(T50%和T90%)分别为11.4和16.3 ℃;氧化甲苯的T50%和T90%分别为210和225 ℃。基于大量的表征结果和多组催化活性数据分析发现,棒状4%Au/α-MnO2催化剂催化活性最好的主要原因是其低温还原性能最好、吸附氧物种浓度较高、催化剂上的Au纳米粒子高度分散、Au纳米粒子与α-MnO2纳米棒之间有较强相互作用。
-
关键词:
- 不同形貌 /
- Au/α-MnO2催化剂; /
- 一氧化碳氧化 /
- 甲苯氧化
Abstract: 1-D nanosized rod-like, wire-like, and tubular α-MnO2 (xAu/α-MnO2,x=2%,4%,8%,10%) were prepared using the hydrothermal and PVA-protected NaBH4 reduction methods at different temperatures with KMnO4 and/or MnSO4 as Mn source, respectively. It is shown that the α-MnO2 in xAu/α-MnO2 was tetragonal in crystal structure, surface area of α-MnO2 nanorods, nanowires, and nanotubes was in the range of 48.4-114.0 m 2/g. The 4%Au/α-MnO2 sample possessed the highest adsorbed oxygen species concentration and the best low-temperature reducibility, thus showing the highest catalytic activity: the T50% and T90% (temperatures required for achieving reactant conversions of 50% and 90%) were 11.4 and 16.3 ℃ for CO oxidation, and 210 and 225 ℃ for toluene oxidation at a space velocity of 20 000 mL/(g ·h), respectively. Based on the characterization results and activity data, it is concluded that the better low-temperature reducibility, higher oxygen adspecies concentration, highly dispersed Au NPs, and stronger interaction between Au NPs and MnO2 nanorods were the main factors influencing the catalytic performance of 4%Au/α-MnO2. -
[1] BLASIN-AUBE V, BELKOUCH J, MONCEAUX L . General study of catalytic oxidation of various VOCs over La0.8Sr0.2MnO3+x perovskite catalyst:influence of mixture[J]. Applied Catalysis B:Environmental, 2003,43(2):175-186.
doi: 10.1016/S0926-3373(02)00302-8[2] ZHENG D S, SUN S X, FAN W L , et al. One-step preparation of single-crystalline β-MnO2 nanotubes[J]. Journal of Physical Chemistry B, 2005,109:16439-16443.
doi: 10.1021/jp052370l[3] YUAN C Z, GAO B, SU L H , et al. Interface synjournal of mesoporous MnO2 and its electrochemical capacitive behaviors[J]. Journal of Colloid and Interface Science, 2008,322:545-550.
doi: 10.1016/j.jcis.2008.02.055 pmid: 18417147[4] LIANG S H, TENG F, BULGAN G , et al. Effect of phase structure of MnO2 nanorod catalyst on the activity for CO oxidation[J]. Journal of Physical Chemistry C, 2008,112:5307-5315.
doi: 10.1021/jp0774995[5] HICKEY N, FORNASIERO P, KAPAR J , et al. Effects of the nature of the reducing agent on the transient redox behavior of NM/Ce0.68Zr0.32O2(NM=Pt,Pd,and Rh)[J]. Journal of Catalysis, 2001,200(1):181-193.
doi: 10.1006/jcat.2001.3201[6] FORNASIERO P, KAPAR J, SERGO V , et al. Redox behavior of high-surface-area Rh-,Pt-,and Pd-loaded Ce0.5Zr0.5O2 mixed oxide[J]. Journal of Catalysis, 2001,202(1):56-59.
doi: 10.1006/jcat.1998.2321[7] THORMÄHLEN L P, SKOGLUNDH M, FRIDELL E , et al. Low-temperature CO oxidation over platinum and cobalt oxide catalysts[J]. Journal of Catalysis, 1999,188(2):300-310.
doi: 10.1006/jcat.1999.2665[8] HOFLUND G B, GARDNER S D, SCHRYER D R , et al. Au/MnOx catalytic performance characteristics for low-temperature carbon monoxide[J]. Applied Catalysis B:Environmental, 1995,B6(2):117-126.
doi: 10.1016/0926-3373(95)00010-0[9] 周仁贤, 郑小明 . Pt/Al2O3,Pd/Al2O3催化剂上CO氧化与表面氧脱出-恢复性能[J]. 催化学报, 1995,16(4):324-327.ZHOU R X, ZHENG X M . Oxidation of CO and surface oxygen property on Pt/Al2O3 and Pd/Al2O3[J]. Chinese Journal of Catalysis, 1995,16(4):324-327. [10] SCHRYER D R, UPCHURCH B T, VAN NORMAN J D , et al. Effects of pretreatment conditions on a Pt/SnO2 catalyst for the oxidation of CO in CO2 lasers[J]. Journal of Catalysis, 1990,122(1):193-197.
doi: 10.1016/0021-9517(90)90270-T[11] SHEINTUCH M, SCHMIDT J, LECTHMAN Y , et al. Modelling catalyst-support interactions in carbon monoxide oxidation catalyzed by Pd/SnO2[J]. Applied Catalysis, 1989,49(1):55-65.
doi: 10.1016/S0166-9834(00)81421-9[12] DONG G L, WANG J G, GAO Y B , et al. Preparation and characterization of CeO2-TiO2 mixed oxides[J]. Journal of Inorganic Materials, 1999,14(6):873-880.
doi: 10.3321/j.issn:1000-324X.1999.06.007[13] ZHU H Q, QIN Z F, WANG J G , et al. Low temperature oxidation of CO over Pd/CeO2-TiO2 catalysts with different pretreatments[J]. Journal of Catalysis, 2005,233(1):41-50.
doi: 10.1016/j.jcat.2005.04.033[14] 叶青, 霍飞飞, 闫立娜 , 等. α-MnO2负载纳米Au催化剂低温催化氧化CO和苯的性能[J]. 物理化学学报, 2011,27(12):2872-2880.
doi: 10.3866/PKU.WHXB20112872YE Q, HUO F F, YAN L N , et al. Highly active Au/α-MnO2 catalysts for the low-temperature oxidation of carbon monoxide and benzene[J]. Acta Physico-Chimica Sinica, 2011,27(12):2872-2880. doi: 10.3866/PKU.WHXB20112872[15] 郝郑平, 安立敦, 王弘立 . 负载型金催化剂用于室温下CO的消除[J].环境污染与防治, 1996(4):4-5.HAO Z P, AN L D, WANG H L . Supported gold catalyst for removing carbon monoxide at room temperature[J].Environmental Pollution & Control, 1996(4):4-5. [16] 王芳 . 规整形貌MnOx的可控合成及其对甲苯氧化的催化性能研究[D]. 北京:北京工业大学, 2012. -
点击查看大图
计量
- 文章访问数: 703
- HTML全文浏览量: 97
- PDF下载量: 317
- 被引次数: 0
下载:
