摘要
光催化技术具有反应条件温和、无污染、低能耗等特点，因而在环境保护、能源转换、新物质合成等多个方面具有广阔的应用前景。改善光催化活性以及提高太阳光利用率是将这一技术推向实际应用的重要环节。选择小分子有机污染物甲醛为目标降解物不仅具有重要的环保意义，也将对实现有机物的完全矿化提供有益的参考。本文利用XRD、TG－DSC、TEM、XPS等多种分析测试手段，在TiO2和ABO3两个体系进行甲醛的光催化降解，将甲醛的光催化降解从利用紫外光光源转向利用可见光光源，探索了光催化降解活性与光催化材料结构的关系。
首先，在紫外光光源下研究TiO2系列光催化剂对高浓度（50mg/L）甲醛溶液的降解，采用溶胶凝胶法制备出颗粒均匀的纳米TiO2光催化剂；探索出溶胶凝胶法的最佳制备条件；同时采用复合SiO2改性TiO2，适量SiO2的加入可以提高光催化降解甲醛的活性。
在模拟太阳光光源（高压汞灯）下探索钙钛矿型复合氧化物的光催化降解甲醛活性，发现：采用柠檬酸络合法制备的钙钛矿结构LaCoO3，颗粒小、粒径分散均匀、为纳米级；进行对比实验，发现其对低浓度（20mg/L）小分子污染物甲醛具有一定的光催化降解活性，反应3小时达到43.9%。
B位过渡金属的离子对LaBO3的光催化活性有很大影响。采用柠檬酸络合法制备的纳米级钙钛矿型LaBO3（B＝Cr、Mn、Fe、Co、Ni）光催化剂降解甲醛活性规律为：LaNiO3 >LaCoO3 >LaFeO3 >LaMnO3 >LaCrO3，这与B位离子半径、d电子结构以及B位原子的电负性有着密切的关系。由于B位过渡金属离子的不同，外层电子结合能不同、能隙的不同以及电子被激发和转移难易程度的不同，从而导致了光催化活性不同。
比较纳米级钙钛矿SrFeO3与LaFeO3的光催化降解甲醛活性与其结构、表面性能关系，通过XPS分析认为SrFeO3的光催化活性远远高于LaFeO3，主要取决于SrFeO3中表面吸附氧的含量远远大于LaFeO3中表明吸附氧的含量。
Photocatalysis is an attractive approach for environmental protection, energy transformation and functional group transformation because of its advantage such as low-temperature, non-energy intensity and non-pollution. Further improvement on photocatalysts’ activity and efficiency and improvement on the utilization ratio of sunlight are the essential step to apply this novel technology. Choosing little molecular pollution-formaldehyde as the degradation objective is not only significant on the environmental protection, but also provides useful reference for the organic pollutions’ completely decomposition. In this dissertation, both the TiO2 and perovskite ABO3 two systems are used in the photocatalytic degradation of formaldehyde and characterized by XRD、TG－DSC、TEM、XPS and so on. And we change the photocatalytic degradation from using UV light to using visible light, only to find the relationship between the photocatalytic activities and the photocatalysts.
First of all, we study the photocatalytic degradation of formaldehyde under UV light with TiO2 system photocatalysts. We used sol-gel method to prepare well-distributed nano TiO2, and found the best preparation condition of it. Also, we used SiO2 modify the TiO2 photocatalyst, and found that adding a certain amount of SiO2 can improve the activity of TiO2.
Secondly, under imitating sunlight we found nano perovskite LaCoO3 prepared by citric acid complex method has a certain activity of formaldehyde degradation.
And we further discussed the influence of the B site ion to LaBO3. With different B site ion, the LaBO3 showed very different activities for the reaction, the regularity is: LaNiO3>LaCoO3>LaFeO3>LaMnO3>LaCrO3, this regularity has great relation with B ion radius, electron configuration and eletronegativity. Because the difference of B site ion leads to the difference of binding energy, the difference of gap energy and the difference of stimulated degree, and thus lead to the difference of photocatalytic activities.
Finally, we discussed the photocatalytic activities of SrFeO3 and LaFeO3, and found that there exist two kinds of oxygen, crystal oxygen and
adsorbed oxygen, on the surface of both SrFeO3 and LaFeO3. According to the results of XPS analysis, content of adsorbed oxygen in SrFeO3 is higher than in LaFeO3, and this lead to photocatalytic oxidation activity of SrFeO3 is higher than LaFeO3.
引文
Fujishima A., Honda K. Electrochemical photolysis water at a semiconductor electrode. Nature, 1972, 238: 37-38
Bard A J. Photoelectrochemistry. Science, 1980, 207: 139
Rosenberg L, Brock J R, Heller A. Collection optics of TiO2 photocatalyst on hollow glass microbeads floating on oil slicks. J. Phys. Chem., 1992, 96: 3423
Word A. Chem. Mater., 1993, 5: 280
Jimmy C, et al. Bull Chem. Soc. Japan, 1974, 147: 1064
Tanabe K, et al. Ti1-xZrxO2 solid solution for the photocatalytic degradation of acetone in air. J. Phys. Chem., 1998, 102: 5094
陈士夫, 赵梦月, 陶跃武．玻璃纤维负载二氧化钛光催化降解有机磷农药．环境科学, 1996, 17(4): 33-35
颜秀茹, 宋宽秀, 霍明亮, TiO2/SiO2的制备及其降解敌敌畏．应用化学, 1999, 16(4): 94-96
邱建斌, 马亚安, 马颖．担载材料对TiO2薄膜光催化活性的影响．物理化学学报, 2000, 16(1)1-4
Aderson C, Bard A J. An improved photocatalyst of TiO2/siO2 prepared by a sol-gol synthesis. J. Phys. Chem., 1995, 99(24)9882-9885
Hidaka H, Asai Y, Zhao J, et al. Photoelectrochemical decomposition fo surfactants on a TiO2/PCO particles film electrode assembly. J. Phys. Chem., 1995, 99(20): 8244-8248
李田, 仇雁翎．水中六六六与四氯苯酚的光催化氧化．环境科学, 1996, 17(1): 24-26
Sclafani A, Palmisamo I, Schiavello M. Difference of the preparation methods of TiO2 on the photocatalytic degradation of phenol in aqueous dispersion. J. Phys. Chem., 1990, 94: 829-832
王怡中, 符雁, 汤鸿霄．甲基橙溶液多相光催化降解研究．环境科学, 1998, 19(1): 1-4
Kozlov K V, Pankshtis E A, savinov E N. The comparative studies of titanium dioxide in gas-phase ethanol photocatalytic oxidation by the FTIR in situ method. Appl. Cata. B: Environ, 24: 7-12
Obee, T.N, Brown, R.T. TiO2 photocatalysis for indoor air applications: Effects of humidity and trace contaminant levels on the oxidation rates of formaldehyde, toluene, and 1, 3-butadiene. Environ. Sci. Technol. 1995, 29 (5): 1223-31
Jongh PED, Vanmackelbergh D, Kelly JJ. Cu2O: a catalyst for the photochemical decomposition of water. Chem. Commun, 1999, 12: 1069-1070
Yue P L, Khan F, Rizzuti L, Chem. Eng. Sci., 1983, 38(11): 1893
Hoffman A J, Carraway ER, Hoffman MR. Environ. Sci. Technol., 1994, 28(5): 776
Tada H, Hyodo M, Kawahara H. Photoinduced polymerization of 1, 3, 5, 7-tetrmethylcyclotetrassloxane by TiO2 particles. J. Phys. Chem., 1991, 95: 10185
Becker W G, Truong M M, et al. Interfacial factors that affect the photoefficiency of semiconductor-sensitized oxidation in nonaqueous media. J. Phys. Chem., 1989, 93: 4882
Hoffman A J, Yet H, Hills G, et al, Photoinduced polymerization of methlmethacrylate using Q-sized ZnO collids. J. Phys. Chem., 1992, 96: 5540
Goren Z, et al. Selective photoreduction of CO2.HCO3- to fomate by aqueous suspensions and collids of Pd-TiO2, J. Phys. Chem., 1990, 94: 3784-390
徐用军, 陈福明等．载钯TiO2半导体悬浮催化体系中CO2的光还原．感光科学和光化学, 1999, 17(1): 61-65
付贤智, 李旦振．提高多相光催化氧化过程效率的新途径．福州大学学报(自科), 2000, 29(6): 104-115
Okte A N, Resat M S. Quantum yields and relative photonic efficiencies of substituted 1, 3-dihydroxybenzenes. J. Photochem. Photobiol. A: chemistry, 2000, 134: 59-70
Hsian V H, Chang C F, Chen Y H. Appl. Catal., B: Environ, 2001, 31: 241
Dijkstra M FJ, Michorius A, Buwalda H, Panneman H J, Et al, Comparison of the efficiency of immobilized and suspended systems in photocatalytic degradation. Catalysis Today. 2001, 66: 487-494
Hoffman M R, Martin S T, et al. Environmental Applications of Semiconductor photocatalysis. Chem. Rev., 1995, 95: 69-96
Linsebigler A L, et al. Photocatalysis on TiO2 surface: Principles, Mechanisms and Selected Results. Chem. Rev., 1995, 95: 735-738
Hoffman A J, Hills G, Yee H, et al. Q-sized CdS: synthesis, characterization, and efficience of photoinitiation of polymerization of several vinylic monomers. J. Phys. Chem., 1992, 96(13): 5546
Hava M, Konodo T, Komoda M, et a1.Cu 2O photocatalyst for overall water splittting under visible light irradiation．Chem. Commun(Cambridge), 1998(3): 357
陈金毅, 刘小玲等． 纳米氧化亚铜可见光催化分解亚甲基蓝．华中师范大学
学报(自然科学版), 2002, 36(2): 200-203
井立强, 孙晓君, 郑大方等．ZnO超微粒子的量子尺寸效应和光催化性能．哈尔滨工业大学学报, 2001, 33(3): 344-348
张虎勤, 陈开勋, 金振声．Pt/CdS光催化剂表面修饰和表面结构．应用化学, 1997, 14(1): 98—100
岳林海, 周永秋．Ag/ZnO光催化降解甲基对硫磷研究．环境污染与防治, 1998, 20(３): 5
陶跃武, 钟顺和．铋钼复合氧化物表面上激光促进异丁烷选择氧化制甲基丙烯酸．催化学报, 2001, 22(2): 129-132
崔高峰, 王伯勇, 王清等． TiO2在不同基质上光催化活性的比较．工业水处理, 2001, 21(7): 26—27
Zhang S G, Fujii Y, Yamashita H, Koyano K, Tatsumi T and Anpo M. Photocatalytic reduction of CO2 with H2O on Ti-MCM-41 and Ti-MCM-48 mesoporous Zeolites at 328K. Chem. Lett., 1997, 659.
Xin Jing, Chen Xi-hui, Suo Ji-shuan, Zhang Xiao-ming, Yan Liang, Li Shu-ben. Photocatalytic oxidation of methane over Nb-MCM-41 mesoporous molecular sieve catalyst under mild conditions. 分子催化, 2001, 15(3), 219
Woo-sung Ju, Masaya Matsuoka and Masakazu Anpo. The photocatalytic reduction of nitrous oxide with propane on lead (II)ion-exchanged ZSM-5 catalysts. Catal. Lett., 71(2001): 91
李越湘, 吕功煊, 李树本．半导体光催化分解水研究进展．分子催化, 2001, 15(1): 72
Yihang Guo, Danfeng Li, Changwen Hu, Yonghui Wang, Enbo Wang, Yongchun Zhou, Shouhua Feng. Photocatalytic degradation of aqueous organchlorine pesticide on the layered double hydroxide pillared by paratungstate A ion, Mg12Al6(OH)36(W7O24)·4H2O. Applied Catalysis B: Enviromental, 30(2001), 337—349
金星龙, 朱琨, 房彦军等．高分子金属卟啉光催化氧化处理废水．催化学报, 2001, 22(2), 189—192
Wang R M, Li Sh B, Wang Y P et al. Sheet polymer and its complexes II preparation and catalytic activity of polymeric tetrakisphenylporphyrin films crosslinked by 4, 4|-Biphenylene-Bisufoate. J. Appl. Polym. Sci., 1998, 67(12): 2027
管英福, 邓麦村, 金美芳等．微藻光生物水解制氢技术．中国生物工程杂志, 2003, 23(4): 8-13
Puma G L, Yue P L. A novel fountain photoctalytic reactor: model development
and experimental validation. Chemical Engineering Science, 2001, 56: 2733-2744
颜秀茹, 李晓红, 宋宽秀等．固定相二氧化钛光催化剂及其反应器研究进展．化工进展, 2002, (2): 12-16
谢翼飞, 李国欣, 李旭东．固定相二氧化钛光催化反应器处理废水的研究现状与进展．给水排水, 2002, 28(8): 63-67
范益群, 史载锋, 徐南平等．光催化膜反应器用于亚甲基蓝的降解．南京化工大学学报, 1999, 21(5): 49-52
Hisashi H, et al. Sonophotocatalytic decoposition of water using TiO2 photocatalyst. Ultrasonics sonochemistry, 2001, 8: 55-58
Vinodgopal K, et al. Enhanced rates of photocatalytic degradation of an AZO dye using SnO2/TiO2 coupled semiconductor thin films. Environmental Science ＆ Technology, 1995, 29(3): 841-845
王怡中．二氧化钛悬浆体系中八种染料的太阳光催化降解．催化学报, 2000, 23(1): 37
陶跃武, 赵梦月, 陈士夫等．空气中有害物质光催化去除．催化学报, 1997, 18(4): 345—347
S. Kakaoka, D. T. Tompkins, W. A. Zeltner, et al. Photocatalytic oxidation in the presence of microwave irradiation: observations with ethylene and water. Journal of photochemistry and photobiology A: Chemistry, 148(2002): 323-330
S. Horikoshi, H. Hidaka, N. Serpone. Enviromental remediation by an integrated microwave/UV-illumination method 1.microwave-assisted degradation of Rhodamine-B dye in aqueous TiO2 dispersions. Environ. Sci. Technol., 2002, 36: 1357-1366
刘淼, 董德明, 张白羽等． 光催化法处含铬(VI)废液．吉林大学自然科学学报, 1998(2): 99—101
Bhakta D, Shukla S S, Chandrasekharaiah M S and Margrave J L. A novel photocatalytic method for detoxification of cyanide wastes. Environ. Sci. Technol., 1992, 26(3): 625—626
井立强, 孙晓君, 徐自立等． ZnO超微粒子光催花氧化SO2的研究．催化学报, 2002, 23(1): 37
Sclafani A, Mozzanega M N, Herrmann J M. Influence of silver deposits on the photocatalytic activity of titania. J. Catal., 1997, 168(1): 117
Herrmann J M, Disdier J, Pichat P, et al. Titania-supported Bimetallic catalyst synthesis by photocatalytic codeposition at ambient temperature: preparation and characterization of Pt-Rh, Ag-Rh and Pt-Pd couples. J.Catal., 1991(132): 490
Tada H, Hyodo M, Kawahara H. Photoinduced polymerization of 1, 3, 5, 7-tetramethylcyclotetrasiloxane by TiO2 particles. J. Phys. Chem., 1991, 95(24): 10185
Karaktisou K E, Verykios X E. Definition of the intrinsic rate of photocatalytic cleavage of water over Pt-Ru/TiO2 catalysts. J. Catal., 1995, 152(2): 360
Yue P L, Khan F, Rizzuti L. Photocatalytic ammonia synthesis in a fluidized bed reactor. Chem. Eng. Sci., 1983, 38(11): 1893
Chatterjee, Debabrata; Mahata, Anima. Visible light induced photodegradation of organic pollutants on dye adsorbed TiO2 surface. Journal of Photochemistry and Photobiology A: Chemistry, 153(2002): 199-204
Cai R, Hashimoto K, Itoh K eral ; Photokilling of Malignant cells with Ultrafine TiO2 powder. Bull. Chem.. Soc. Jpn., 1991, 64 (4) : 1268
Cai R, Hashimoto K, Kubota Y. et al , Increment of. Photocatalytic . killing of Cancer cells Using .TiO2 with the Acid of superoxide Dismutase. Chem. Lett. 1992, 243(3), 427-430
Pena M A and Fierro J L G. Chem Rev. 2001, 0(7): 1981-2017
Parravano G, J Am Chem Soc., 1953, 75: 1497
Kawai T, Kunimori K, Kondow T et al, Phys Chem., NF 1973, 86: 268
Libby W F. Science , 1975, 171: 499
Kremenic G, Nieto J M L, Tascon J M D et al. Chem Soc, Faraday Trans.1, 1985, 81: 939
Gunasekaran N, Rajadurai S, Carberry J. J Catal Leet. 1995, 35: 373
Forni L, Oliva C, Barzetti T et al. Appl Catal B: Environ., 1997, 13: 35
Ward T R, Alemany P, Hoffmann, R. J Phys. Chem., 1993, 97: 7691
Watson P R, Somorijai G A. J. Catal, 1982, 74: 282
Ulla M A, Migone, R A, Petuchi J O et al. J. Catal., 1987, 105: 107
曹曼, 朱云杰, 王玉香等．水中活性艳红K-2BP光催化分解机理初探．环境科学研究, 1993, 6(1): 58-60
Thampi K R, Subba Rao M , Schwarz W et al. J. Chem. Soc. Faraday Trans 1 1988, 84: 1703
Mitsui C, Noshiguchi H, Fukamachi K et al. Chem. Lett., 1999, 1327
Kudo A, Kato H., Chem.Phys.Lett., 2000, 331: 373
白树林, 付希贤等．钙钛矿型复合氧化物的光催化活性变化趋势与分析．高等学校化学学报, 2001, 22(4): 663-665
杨秋华, 付希贤等．La1-xSrxFeO3光催化降解水溶性染料．应用化学, 2000, 17(6), 585-588
付希贤, 颜彩凡．LaFe1-xCuxO3光催化降解水溶性染料的活性．催化学报, 1999, 20(6): 623-627
Gu ZR, Chen AP, et al. Active carbon and nano-titanium dioxide photocatalyst web for air purifacation. J. East China Univ. Sci. Tech., 2000, 26 (4): 367-71
Gu ZR, Chen AP, et al. Mechanism of mutual enhancing ability of purification between photocatalysis agent and active carbon on air purification sieve. Chemistry and Industry of Forest Products. 2000, 20 (1): 6-10.
Zhang YH, Xiong GX, et al. Preparation of titania-based catalysts for formaldehyde photocatalytic oxidation from TiCl4 by the sol-gel method. Catalysis Today. 2001, 68 (1-3): 89-95
庚晋．甲醛污染的危害及其来源．质量监督与消费, 2003(1): 22-23
吴树新．改性纳米TiO2光催化氧化还原性能的研究．天津大学博士论文, 2003
卢里耶, 雷布尼科娃卢里耶著, 雷世寰等译．工业废水的化学分析方法．化学工业出版社, 1989: 157
黄惠中．纳米材料分析．化学工业出版社, 2003
杨秋华．纳米钙钛矿型ABO3复合氧化物的光催化氧化还原活性．天津大学博士论文, 2002
李薇, 王怡中．固定化催化剂光反应器降解有机物研究进展．环境污染治理技术与设备, 2003, 3(7): 91-94
余锡宾, 王桂华, 罗衍庆等．二氧化钛微粒的掺杂改性与光催化活性．上海师范大学学报(自科版), 2000, 20(1): 75-82
Sarma D.D., Santra A.K and Rao C. N. R., Electronic Structures of Pervoskite oxides of Transition Metals of the Type LaMO3(M=Ti~Ni) as Revealed by MSX α Investigations. Journal of Solid State Chemistry, 1994, 110: 393-396
Allred A.L., Rochow E. G., J. Inorg. A scale of electronegativity based on electrostatic force. Nucl. Chem., 1957, 5: 264-268
李玉敏. 工业催化原理. 天津大学出版社，1992: 258
Slater J. C.. Atomic shielding constants. Phys. Rev., 1930, 36: 57-64