PMoO/SiO_2非均相催化碘离子氧化研究
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摘要
以正硅酸乙酯(TEOS)为硅源,采用溶胶-凝胶法制备一系列非均相多钼氧簇催化剂(PMoO/SiO_2)。通过FT-IR、XRD、SEM等对其结构加以表征。以过氧化氢为氧化剂、PMoO/SiO_2为催化剂,研究PMoO/SiO_2的负载量、反应温度、pH对催化活性的影响,利用计算机模拟揭示多钼氧簇与二氧化硅之间的相互作用。研究表明:催化剂PMoO/SiO_2在负载量为25%、反应温度45℃、pH=1.4条件下碘离子的氧化反应速率为9.25×10~(-5)mol/(L*s),与未添加催化剂相比,PMoO/SiO_2的催化效果提高6.85×10~3倍。PMoO倾向于物理吸附在不定形SiO_2的富Si面,同时以形成O-H键和O-Si键的形式发生化学相互作用,使得电子从不定形SiO_2向PMoO表面转移,发生协同催化作用。催化剂在循环使用十次之后催化碘离子转化率仍高达86.5%,循环使用性好,无过氧化,具有较好的工业应用前景。
A series of heterogeneous polymolybdenum oxide cluster catalysts(PMoO/SiO_2)were prepared by sol-gel method using tetraethyl orthosilicate TEOS as silicon source.The structure was characterized by FT-IR,XRD,SEM,and the like.The effects of PMoO/SiO_2 loading,reaction temperature and pH on the catalytic activity were investigated by using hydrogen peroxide as oxidant and PMoO/SiO_2 as catalyst.and the interaction between molybdenum oxygen clusters and silica was revealed by theoretical simulation.The results show that there is not only physical adsorption but also chemical adsorption between polymolybdenum oxygen clusters and silicon dioxide to enhance their stability.The research shows that the catalyst PMoO/SiO_2 has an iodide ion oxidation rate of 9.25×10~(-5)mol/(L*s)under the conditions of 25%loading,reaction temperature 45℃ and pH=1.4,The catalytic effect of PMoO/SiO_2 was improved by 6.85×10~3 times compared with the catalyst without addition.PMoO tends to physically adsorb on Si rich surface of amorphous SiO_2,and at the same time,chemical interaction takes place in the form of O-H bond and O-Si bond,so that electrons transfer from amorphous SiO_2 to the surface of PMoO and synergistic catalysis takes place.he catalytic iodide ion conversion rate is still as high as 86.5%after the catalyst is used for 10 times.,which has good recycling performance and no peroxide,and has a good industrial application prospect.
A series of heterogeneous polymolybdenum oxide cluster catalysts(PMoO/SiO_2)were prepared by sol-gel method using tetraethyl orthosilicate TEOS as silicon source.The structure was characterized by FT-IR,XRD,SEM,and the like.The effects of PMoO/SiO_2 loading,reaction temperature and pH on the catalytic activity were investigated by using hydrogen peroxide as oxidant and PMoO/SiO_2 as catalyst.and the interaction between molybdenum oxygen clusters and silica was revealed by theoretical simulation.The results show that there is not only physical adsorption but also chemical adsorption between polymolybdenum oxygen clusters and silicon dioxide to enhance their stability.The research shows that the catalyst PMoO/SiO_2 has an iodide ion oxidation rate of 9.25×10~(-5)mol/(L*s)under the conditions of 25%loading,reaction temperature 45℃ and pH=1.4,The catalytic effect of PMoO/SiO_2 was improved by 6.85×10~3 times compared with the catalyst without addition.PMoO tends to physically adsorb on Si rich surface of amorphous SiO_2,and at the same time,chemical interaction takes place in the form of O-H bond and O-Si bond,so that electrons transfer from amorphous SiO_2 to the surface of PMoO and synergistic catalysis takes place.he catalytic iodide ion conversion rate is still as high as 86.5%after the catalyst is used for 10 times.,which has good recycling performance and no peroxide,and has a good industrial application prospect.
引文
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[21]徐明波,乐艳,侯倩,等.二氧化硅负载硅钨钼酸催化合成环己酮1,2-丙二醇缩酮[J].化学研究与应用,2012,24(9):1409-1412.
[22]Vollmayr K,Kob W,Binder K.Cooling-rate effects in amorphous silica:A computer-simulation study[J].Physical Review B Condensed Matter,1996,54(22):15808-15827.
[23]Yang J,Michael J,Janik,et al.Location,acid strength,and mobility of the acidic protons in Keggin 12-H3PW12O40:A combined solid-State NMR spectroscopy and DFT quantum chemical calculation study[J].Journal of the American Chemical Society,2005,51(127),18274-18280.
[2]张邦彦.工业射线胶片乳剂制备技术的新进展[J].影像技术,2004(2):40-42.
[3]Madhu S,Evans H A,Doan-Nguyen V V T,et al.Inside back cover:infinite polyiodide chains in the pyrroloperylene-iodine complex:insights into the starch–iodine and perylene-iodine complexes[J].Angewandte Chemie,2016,55(28):8135-8135.
[4]Schreiber M,Vivekanandhan S,Mohanty A K,et al.Iodine treatment of lignin–cellulose acetate electrospun fibers:enhancement of green fiber carbonization[J].Acs Sustainable Chemistry&Engineering,2015,3(1):33-41.
[5]Zhao Q,Lu Y,Zhu Z,et al.Rechargeable Lithium-iodine batteries with iodine/nanoporous carbon cathode[J].Nano Letters,2015,15(9):5982–5987.
[6]Copper C L,Koubek E.Kinetics of the molybdate and tungstate catalyzed oxidation of iodide by hydrogen peroxide[J].Inorganica Chimica Acta,1999,288(2):229-232.
[7]Karunakaran C,Muthukumaran B.Molybdenum(VI)catalysis of perborate or hydrogen peroxide oxidation of iodide ion[J].Transition Metal Chemistry,1995,20(5):460-462.
[8]Melicher■ík M,Olexová A,L′udovít T.Kinetics of the oxidation of iodine by hydrogen peroxide catalyzed by MoO42-,ions[J].Journal of Molecular Catalysis A Chemical,1997,127(1-3):43-47.
[9]Jin D,Yang X,Zhang M,et al.Fabricate hollow Ag–POMs microtubule by a simple process[J]Materials Letters,2015,141:128-131.
[10]周维珍.膨润土负载磷钼酸催化碘离子氧化反应的研究[J].无机盐工业,2017,49(10):62-66.
[11]Long D L,Cronin L.Towards polyoxometalate-integrated nanosystems[J].Chemistry-A European Journal,2010,12(14):3698-3706.
[12]Tang R,Chen T,Wang G.The immobilized methods and applications of heteropoly compound catalyst[J].Chemical Industry&Engineering Progress,2013,11(2):551-558.
[13]Gong S W,Wang X Y,Li K,et al.Nitration of benzene catalyzed by supported ammonium molybdophosphat catalyst[J].Chinese Journal of Applied Chemistry,2010,27(04):428-431.
[14]Zhi-Hong M,Jie W,Li G,et al.Synthesis of benzaldehyde cylic ethylic acetal by the H5PMo10V2O40 immobilized on silylated palygorskite[J].Journal of Molecular Catalysis,2011,25(5):393-399.
[15]周德志,肖彬,曹小华.MCM-41负载Dawson型磷钨酸的制备及其对乙酸与正丁醇酯化反应的催化性能研究[J].化学研究与应用,2018,30(05):773-778.
[16]陈霄榕,李永丹,康慧敏,等.SiO2与Keggin杂多酸相互作用的研究[J].分子催化,2002,16(1):60-64.
[17]王晓夏,徐华龙,沈伟,等.三元杂化TiO2-SiO2-POMs催化剂的合成及其在可见光降解罗丹明B中的应用[J].物理化学学报,2013,29(9):837-1841.
[18]张跃伟,宁波,陈峰.SiO2负载的杂多酸催化剂制备及其在合成异戊二烯反应中性能研究[J].应用化工,2017,46(10):1985-1987.
[19]Kendel S.Comprehensive study of isobutane selective oxidation over group I and II phosphomolybdates:structural and kinetic factors[J].Catalysis Letters,2011,141(12):1767-1785.
[20]Langpape M,Millet J M M,Ozkan U S,et al.Study of cesium or cesium-transition metal-substituted Keggin-type phosphomolybdic acid as isobutane oxidation catalysts:I.structural characterization[J].Journal of Catalysis,1999,181(1):80-90.
[21]徐明波,乐艳,侯倩,等.二氧化硅负载硅钨钼酸催化合成环己酮1,2-丙二醇缩酮[J].化学研究与应用,2012,24(9):1409-1412.
[22]Vollmayr K,Kob W,Binder K.Cooling-rate effects in amorphous silica:A computer-simulation study[J].Physical Review B Condensed Matter,1996,54(22):15808-15827.
[23]Yang J,Michael J,Janik,et al.Location,acid strength,and mobility of the acidic protons in Keggin 12-H3PW12O40:A combined solid-State NMR spectroscopy and DFT quantum chemical calculation study[J].Journal of the American Chemical Society,2005,51(127),18274-18280.