负载型贵金属低温催化氧化甲醛催化剂的研究
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摘要
制备贵金属低温催化氧化甲醛催化剂,研究了催化剂结构特征及催化氧化甲醛机理,并考察了催化剂性能。采用沉积-沉淀法制备负载型贵金属低温催化氧化甲醛催化剂,优化组成及制备条件,采用XRD、FT-IR、H_2-TPR、拉曼等对催化剂进行表征分析。催化剂最佳制备条件:NaOH为沉淀剂,载体n(Cu)/n(Mn)摩尔比为1∶2,Pt负载量(质量分数)为1%,载体制备pH为9—10,贵金属负载pH为9.5。Pt_1/Cu_(0.5)Mn催化剂以非化学计量比Cu_(0.9)Mn_(1.8)O_4无定形态晶体特征峰存在,Pt金属在载体表面分布均匀,且贵金属与载体相互作用使催化剂表面氧缺位浓度增加,表面活性氧物种增多,催化剂在室温下表现出良好的稳定性和重复性。室温下甲醛和氧气在催化剂表面共吸附,甲醛首先被催化剂表面活性氧氧化为DOM,由于DOM很活跃,在催化剂上很快被表面氧氧化成甲酸根,甲酸根在催化剂表面氧和气相氧的共同作用下氧化生成CO,最终被完全氧化为CO_2。其中甲酸盐物种向CO转化步骤是整个反应的速控步骤。
A serious of noble metal catalysts for the oxidation of formaldehyde at low temperature was prepared. The structural characteristics and catalytic oxidation mechanism of formaldehyde of the catalysts were studied. The catalysts were prepared by a precipitation method and characterized by XRD, FT-IR, H_2-TPR, Raman spectroscopy. The results show that the Pt/CuMn catalysts exhibited high activity and the best preparation conditions are as follows: NaOH as precipitation agent, Cu/Mn ratio of carrier is 1 ∶2, Pt load(mass fraction) of 1%, carrier precipitation pH is 9-10, catalyst preparation pH is 9.5. The main phases of Pt1/Cu0.5 Mn catalyst were Cu_(0.9)Mn_(1.8)O_4 under the preparation conditions, Pt uniform distribution in the surface of carrier and the surface reactive oxygen species of the catalyst was promoted by the synergetic effect of Pt and carrier as well as the catalytic activity, the catalyst showed good stability and repeatability at room temperature. It was found that formaldehyde could be oxidized to DOM first by surface reactive oxygen species when formaldehyde and oxygen adsorption to the catalyst surface together, and then DOM will be oxidized to formate quickly, formate be oxidized to CO and CO_2 completely by surface reactive oxygen and gas phase finally, and the decomposition of formate was the key step in the whole reaction.
A serious of noble metal catalysts for the oxidation of formaldehyde at low temperature was prepared. The structural characteristics and catalytic oxidation mechanism of formaldehyde of the catalysts were studied. The catalysts were prepared by a precipitation method and characterized by XRD, FT-IR, H_2-TPR, Raman spectroscopy. The results show that the Pt/CuMn catalysts exhibited high activity and the best preparation conditions are as follows: NaOH as precipitation agent, Cu/Mn ratio of carrier is 1 ∶2, Pt load(mass fraction) of 1%, carrier precipitation pH is 9-10, catalyst preparation pH is 9.5. The main phases of Pt1/Cu0.5 Mn catalyst were Cu_(0.9)Mn_(1.8)O_4 under the preparation conditions, Pt uniform distribution in the surface of carrier and the surface reactive oxygen species of the catalyst was promoted by the synergetic effect of Pt and carrier as well as the catalytic activity, the catalyst showed good stability and repeatability at room temperature. It was found that formaldehyde could be oxidized to DOM first by surface reactive oxygen species when formaldehyde and oxygen adsorption to the catalyst surface together, and then DOM will be oxidized to formate quickly, formate be oxidized to CO and CO_2 completely by surface reactive oxygen and gas phase finally, and the decomposition of formate was the key step in the whole reaction.
引文
[1] 张长斌,贺泓,王莲,等. 负载型贵金属催化剂用于室温催化氧化甲醛和室内空气净化[J].科学通报,2009,54(3):278-286.
[2] WANG Renhu, LI Junhua. OMS-2 catalysts for formaldehyde oxidation: Effects of Ce and Pt on structure and performance of the catalysts[J]. Catalysis Letters, 2009, 131(3/4): 500-505.
[3] PENG Jiaxi, WANG Shudong. Performance and characterization of supported metalcatalysts for complete oxidation of formaldehyde at low temperatures[J]. Applied Catalysis B: Environmental, 2007, 73(3/4): 282-291.
[4] ZHANG Changbin, HE Hong, TANAKA Kenichi. Catalytic performance and mechanism of a Pt/TiO2 catalyst for the oxidation of formaldehyde at room temperature[J]. Appl Catal B, 2006, 65(1/2): 37.
[5] AVAREZ M C, DELA PENA O′SHEA V A, FIERRO J L G, et al. Alumina supported manganese and manganese palladium oxide catalysts for VOCs combustion[J]. Catalysis Communications, 2003, 4(5):223-228.
[6] SHEN Yuenian, YANG Xuzhang, WANG Yizheng, et al. The states of gold species in CeO2 supported gold ca-talyst for formaldehyde oxidation[J]. Appl Catal B, 2008, 79(2): 142-148.
[7] TANG Xingfu,CHEN Junli, LI Yonggang,et al. Complete oxidation of formaldehyde over Ag/MnOx-CeO2 ca-talysts[J]. Chem Eng J, 2006,118(1/2):119-125.
[8] ZHANG Changbin,SHI Xiaoyan,GAO Hongwei,et al.Elimination of formaldehyde over Cu-Al2O3 at room temperature[J]. J Environ Sci,2005,17(3):429-432.
[9] 李玮,黄丽丽,翟友存,等. 新型Cu-Mn/TiO2和Cu-Mn/γ-Al2O3甲醛催化氧化催化剂的研制及活性[J]. 化工进展,2015,34(1):127-132.
[10] 张娜,罗孟飞,鲁继青.CeO2分散度对Au/CeO2-SiO2催化剂上甲醛的催化氧化影响[J]. 中国稀土学报,2011,29(6):674-678.
[11] VICENTE M A, BELVER C, TRUJILLANO R, et al. Preparation and characterisation of Mn- and Co-supported catalysts derived from Al-pillared clays and Mn- and Co-complexes[J]. Applied Catalysis A: General, 2004, 267(1/2): 47-58.
[12] 黄海风,唐伟. CuMn复合氧化物及稀土助剂对VOCs催化燃烧性能的研究[J]. 浙江工业大学学报,2004,32(4):407-410.
[13] 李明. 空气净化用铜锰复合氧化物的研究[D]. 北京:北京化工大学,2007.
[14] 李俊. VOCs净化用铜锰复合氧化物催化剂的研究[D]. 广州:广东工业大学,2012.
[15] 何运兵,纪红兵. 温和条件下甲醛在Pt/TiO2上催化氧化反应的原位漫反射红外光谱研究[J]. 催化学报,2010,31(2):171-175.
[16] SENANAYAKE S D, CHONG S V, IDRISS H. The reactions of formaldehyde over the surfaces of uranium oxides. Acomparative study between polycrystalline and single crystal materials[J]. Catalysts Today, 2003,85(2/3/4): 311-320.
[2] WANG Renhu, LI Junhua. OMS-2 catalysts for formaldehyde oxidation: Effects of Ce and Pt on structure and performance of the catalysts[J]. Catalysis Letters, 2009, 131(3/4): 500-505.
[3] PENG Jiaxi, WANG Shudong. Performance and characterization of supported metalcatalysts for complete oxidation of formaldehyde at low temperatures[J]. Applied Catalysis B: Environmental, 2007, 73(3/4): 282-291.
[4] ZHANG Changbin, HE Hong, TANAKA Kenichi. Catalytic performance and mechanism of a Pt/TiO2 catalyst for the oxidation of formaldehyde at room temperature[J]. Appl Catal B, 2006, 65(1/2): 37.
[5] AVAREZ M C, DELA PENA O′SHEA V A, FIERRO J L G, et al. Alumina supported manganese and manganese palladium oxide catalysts for VOCs combustion[J]. Catalysis Communications, 2003, 4(5):223-228.
[6] SHEN Yuenian, YANG Xuzhang, WANG Yizheng, et al. The states of gold species in CeO2 supported gold ca-talyst for formaldehyde oxidation[J]. Appl Catal B, 2008, 79(2): 142-148.
[7] TANG Xingfu,CHEN Junli, LI Yonggang,et al. Complete oxidation of formaldehyde over Ag/MnOx-CeO2 ca-talysts[J]. Chem Eng J, 2006,118(1/2):119-125.
[8] ZHANG Changbin,SHI Xiaoyan,GAO Hongwei,et al.Elimination of formaldehyde over Cu-Al2O3 at room temperature[J]. J Environ Sci,2005,17(3):429-432.
[9] 李玮,黄丽丽,翟友存,等. 新型Cu-Mn/TiO2和Cu-Mn/γ-Al2O3甲醛催化氧化催化剂的研制及活性[J]. 化工进展,2015,34(1):127-132.
[10] 张娜,罗孟飞,鲁继青.CeO2分散度对Au/CeO2-SiO2催化剂上甲醛的催化氧化影响[J]. 中国稀土学报,2011,29(6):674-678.
[11] VICENTE M A, BELVER C, TRUJILLANO R, et al. Preparation and characterisation of Mn- and Co-supported catalysts derived from Al-pillared clays and Mn- and Co-complexes[J]. Applied Catalysis A: General, 2004, 267(1/2): 47-58.
[12] 黄海风,唐伟. CuMn复合氧化物及稀土助剂对VOCs催化燃烧性能的研究[J]. 浙江工业大学学报,2004,32(4):407-410.
[13] 李明. 空气净化用铜锰复合氧化物的研究[D]. 北京:北京化工大学,2007.
[14] 李俊. VOCs净化用铜锰复合氧化物催化剂的研究[D]. 广州:广东工业大学,2012.
[15] 何运兵,纪红兵. 温和条件下甲醛在Pt/TiO2上催化氧化反应的原位漫反射红外光谱研究[J]. 催化学报,2010,31(2):171-175.
[16] SENANAYAKE S D, CHONG S V, IDRISS H. The reactions of formaldehyde over the surfaces of uranium oxides. Acomparative study between polycrystalline and single crystal materials[J]. Catalysts Today, 2003,85(2/3/4): 311-320.