采用共沉淀法制备了一系列不同SiO2-3插层的Ni-Al类水滑石(Ni-Al LDH),在550℃下焙烧后评价其在乙醇氧化反应中的催化活性。并通过XRD、FT-IR、N2吸-脱附、H2-TPR和NH3-TPD等技术进行表征。结果表明,成功制备了SiO2-3插层Ni-Al水滑石;在反应温度为500℃时,Ni-Al-SiO2-3 LDH[n(Si/Al)=1.5]的焙烧产物作为催化剂表现出优异的乙醇转化率和二氧化碳选择性,分别为98%和97%。层间适量SiO2-3的引入可以改变前驱体中层板上的金属离子与层间阴离子的相互作用,使得焙烧产物中活性氧化性物种NiO的数量增多且易被还原,进而对氧化反应非常有利;而且使得催化剂显示出更高的比表面积,导致活性组分的分散度大大提高;以及更高含量的低温酸可以减少CO的吸附,进而有利于催化乙醇氧化的高活性和高选择性。
A series of Ni-Al hydrotalcite(LDH) with the intercalation of different SiO2-3 contents were prepared by coprecipitation method.Their catalytic activities in ethanol oxidation were investigated after calcination at 550℃.XRD,FT-IR,BET,H2-TPR and NH3-TPD techniques were used to characterize the prepared samples,and it indicated that Ni-Al LDH with the intercalation of SiO2-3 were successfully obtained.At the reacting temperature of 500℃,the calcined product of Ni-Al-SiO2-3 LDH[n(Si/Al)=1.5] exhibited excellent ethanol conversion(98%)and carbon dioxide selectivity(97%).The results showed that the interactive force between the metal ions on the layers and the interlayer anions in the precursor layer can be changed by the appropriate amount of SiO2-3 intercalating the Ni-Al LDH.Therefore the amount of NiO which was the active oxidizing species in the calcined product was increased,and the NiO was easily reduced.As a result,this was benefit to the oxidation reaction.The catalysts also shown higher specific surface area,resulting in a greatly increased dispersion of the active component.And higher contents of low temperature's acid can reduce the adsorption of CO,which was in turn useful for the high activity and the high selectivity in the ethanol oxidation.
[1] 李振宇,李顶杰,黄格省,等.燃料乙醇发展现状及思考[J].化工进展,2013,32(7):1457-1467.
[2] Rintramee K,Karin F,Rupprechter G,et al.Ethanol adsorption and oxidation on bimetallic catalysts containing platinum and base metal oxide supported on MCM-41[J].Applied Catalysis B:Environmental,2012,115/116:225-235.
[3] Li H J,Qi G S,Tana,et al.Low-temperature oxidation of ethanol over a Mn0.6Ce0.4O2 mixed oxide[J].Applied Catalysis B:Environmental,2011,103(1/2):54-61.
[4] 彭雨程,王恒,冯俊小,等.催化燃烧技术处理VOCs的研究进展[J].环境与可持续发展,2015,40(3):97-100.
[5] Guisnet M,Dégé P,Magnoux P,et al.Catalytic oxidation of volatile organic compounds:oxidation of methyl-isobutyl-ketone over Pt/zeolite catalysts[J].Applied Catalysis B:Environmental,2005,57(2):117-123.
[6] Garcia T,Agouram S,Sanchez-royo J F,et al.Deep oxidation of volatile organic compounds using ordered cobalt oxides prepared by a nanocasting route[J].Applied Catalysis A:General,2010,386(1/2):16-27.
[7] Zheng G,Hohn K L.Catalytic oxidation of methanol on nanoscale copper oxide and nickel oxide[J].Industrial & Engineering Chemistry Research,2004,43(1):30-35.
[8] Anna P,Petr B.High temperature x-ray powder diffraction as a t001 for characterization of smectites,layered double hydroxides,and their intercalates with porphyrins[J].Applied Clay Science,20l0,49(4):363-371.
[9] 杜以波,Evans D G,孙鹏,等.阴离子型层柱材料研究进展[J].化学通报,2000,5:20-24.
[10] 谢鲜梅,安霞,吴旭.无机层状化合物的制备及其应用基础研究[M].北京:化学工业出版社,2013.
[11] Arpentinier P,Basile P F,Gallo D,et al.New catalysts with low amounts of active phase for CPO processes[J].Today,2006,117(4):462-467.
[12] DelArco M,Gutiérrez S,Martín C,et al.Effect of the Mg:Al ratio on borate (or silicate)/nitrate exchange in hydrotalcite[J].Solid State Chem,2000,151(2):272-280.
[13] Dávila V,Lima E,Bulbulian S,et al.Mixed Mg(Al)O oxides synthesized by the combustion method and their recrystallization to hydrotalcites[J].Microporous Mesoporous Mater,2008,107(3):240-246.
[14] Yun S K,Constantino V R L,Pinnavaia T J.Synthesis and catalytic properties of silicate-intercalated layered double hyroxides foemed by intragallery hydrolysis of tetraethylorthosilicate[J].Clays Clay Miner,1995,43(4):503-510.
[15] Thangaraj B,Raju K,Jayaraj C,et al.Silicate anion-stabilized layered magnesium-aluminiumhydrotalcite[J].RSC Advances,2013,3(37):16392-16398.
[16] Thangaraj B,Jayaraj C,Ganesh V,et al.Silicate intercalated cobalt chromium-hydrotalcite (CoCr-HTSi):An environment-friendly recyclable catalyst for organic transformations[J].Catalysis Communications,2016,74:85-90.
[17] Albertazzi S,Basile F,Benito P.Effect of silicates on the structure of Ni-containing catalysts obtained from hydrotalcite-type precursors[J].2007,128(3):258-263.
[18] Kantam M L,Rahman A C.Venkat R,et al.The first example of activation of molecular oxygen by Nickel in Ni-Al Hydrotalcite:A novel protocol for the Selective oxidation of alcohols[J].Communications,2001,40(4):763-766.
[19] Zhang S,Guo Y Y.Effffects of large CuO contents on the performance of Pd/Al2O3-CuO catalysts in ethanol oxidation reaction[J].Chemical Physics Letters,2019,722:20-31.
