合成条件对磷钨酸负载的金属有机框架催化剂氧化脱硫性能的影响
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摘要
通过一步水热合成法制备了大比表面积、高脱硫活性的磷钨酸(HPW)负载的金属有机框架HPW@MIL-101(Cr)催化剂,对其进行了FT-IR、XRD和氮吸附等表征,并研究了合成时间、合成温度、酸碱度及HPW负载量等参数对催化剂脱硫性能的影响。结果表明,随着合成时间的延长、合成温度的提高,HPW@MIL-101(Cr)孔道有序度提高;合成温度低于等于140℃时,不能形成M IL-101(Cr)晶体结构;酸性合成条件合成的HPW@M IL-101(Cr)的孔道有序度降低;随着HPW负载量的增加,HPW@MIL-101(Cr)的催化性能呈现先升高后降低的趋势。在12 h、220℃和中性条件下制备得到的负载量为3.5 g的HPW@MIL-101(Cr)催化剂具有最佳脱硫活性;在模拟油20 mL、催化剂用量0.24 g、氧硫比为8和50℃条件下反应120 min,对苯并噻吩、二苯并噻吩和4,6-二甲基二苯并噻吩脱硫率分别为99%、100%和99%;与HPW相比,苯并噻吩脱硫率提高了2.4倍。
A series of phosphotungstic acid( HPW) encapsulated metal-organic HPW @ MIL-101( Cr)catalysts,with high surface area and high activity in the oxidative desulfurization( ODS),were synthesized by one-step hydrothermal method and characterized by FT-IR,XRD and nitrogen physisorption. The influences of synthesis time,temperature,HPW loading,and acidity/alkalinity on the catalytic performance of HPW @ MIL-101( Cr) in ODS were then investigated. The results indicated that the order degree of channels in HPW@ MIL-101( Cr) is improved with the increase of synthesis time and temperature. The crystal structure of MIL-101( Cr)cannot be formed at a synthetic temperature below140 ℃ and the channel order of HPW @ MIL-101( Cr)decreases under an acidic synthetic environment. The catalytic activity of HPW@ MIL-101( Cr) displays a trend of first increasing and then decreasing with the increase of HPW loading. The HPW@ MIL-101( Cr) catalyst with a HPW loading of 3.5 g,synthesized at 220 ℃ under neutral environment for 12 h,exhibits the highest activity in ODS. At 50 ℃,with a catalyst dosage of 0. 24 g,an model oil of 20 mL,and an O/S molar ratio of 8,the desulfurization rates over the HPW@ MIL-101( Cr) catalyst towards benzothiophene,dibenzothiophene,and 4,6-dimethyl dibenzothiophene after reaction for 120 min reach 99%,100% and 99%,respectively; in particular,the desulfurization rate for benzothiophene is 2.4 times higher than that obtained over HPW.
A series of phosphotungstic acid( HPW) encapsulated metal-organic HPW @ MIL-101( Cr)catalysts,with high surface area and high activity in the oxidative desulfurization( ODS),were synthesized by one-step hydrothermal method and characterized by FT-IR,XRD and nitrogen physisorption. The influences of synthesis time,temperature,HPW loading,and acidity/alkalinity on the catalytic performance of HPW @ MIL-101( Cr) in ODS were then investigated. The results indicated that the order degree of channels in HPW@ MIL-101( Cr) is improved with the increase of synthesis time and temperature. The crystal structure of MIL-101( Cr)cannot be formed at a synthetic temperature below140 ℃ and the channel order of HPW @ MIL-101( Cr)decreases under an acidic synthetic environment. The catalytic activity of HPW@ MIL-101( Cr) displays a trend of first increasing and then decreasing with the increase of HPW loading. The HPW@ MIL-101( Cr) catalyst with a HPW loading of 3.5 g,synthesized at 220 ℃ under neutral environment for 12 h,exhibits the highest activity in ODS. At 50 ℃,with a catalyst dosage of 0. 24 g,an model oil of 20 mL,and an O/S molar ratio of 8,the desulfurization rates over the HPW@ MIL-101( Cr) catalyst towards benzothiophene,dibenzothiophene,and 4,6-dimethyl dibenzothiophene after reaction for 120 min reach 99%,100% and 99%,respectively; in particular,the desulfurization rate for benzothiophene is 2.4 times higher than that obtained over HPW.
引文
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[9] DING J W,WANG R. A new green system of HPW@MOFs catalyzed desulfurization using O2as oxidant[J]. Chin Chem Lett,2016,27(5):655-658.
[10] CHEN M,YAN J Q,TAN Y,LI Y F,WU Z M,PAN L S,LIU Y J. Hydroxyalkylation of phenol with formaldehyde to bisphenol F catalyzed by Keggin phosphotungstic acid encapsulated in metal-organic framew orks M IL-100(Fe or Cr)and M IL-101(Fe or Cr)[J]. Ind Eng Chem Res,2015,54(47):11804-11813.
[11] ZHOU Z Y,CHENG B H,MA C,XU F,XIAO J,XIA Q B,LI Z. Flexible and mechanically-stable MIL-101(Cr)@PFs for efficient benzene vapor and CO2adsorption[J]. RSC Adv,2015,5(114):94276-94282.
[12] YANG X,LIU J,FAN K,RONG L. Hydrocracking of jatropha oil over non-sulfided PTA-NiMo/ZSM-5 catalyst[J]. Sci Rep,2017,7:41654.
[13] WAN H,CHEN C,WU Z W,QUE Y G,FENG Y,WANG W,WANG L,GUAN G F,LIU X Q. Encapsulation of heteropolyanion-based ionic liquid w ithin the metal-organic framew ork M IL-100(Fe)for biodiesel production[J]. ChemCatChem,2015,7(3):441-449.
[14] ZHU Y F,ZHU M Y,KANG L H,YU F,DAI B. Phosphotungstic acid supported on mesoporous graphitic carbon nitride as catalyst for oxidative desulfurization of fuel[J]. Ind Eng Chem Res,2015,54(7):2040-2047.
[2] HUANG D,WANG Y J,YANG L M,LUO G S. Chemical oxidation of dibenzothiophene with a directly combined amphiphilic catalyst for deep desulfurization[J]. Ind Eng Chem Res,2006,45:1880-1885.
[3] CAMPOS-MARTIN J M,CAPEL-SANCHEZ M C,PEREZ-PRESAS P,FIERRO J L G. Oxidative processes of desulfurization of liquid fuels[J]. J Chem Technol Biotechnol,2010,85:879-890.
[4] KOMINTARACHAT C,TRAKARNPRUK W. Oxidative desulfurization using polyoxometalates[J]. Ind Eng Chem Res,2006,45:1853-1856.
[5] YUAN D,SONG H,SONG H L,YOU M Y,WANG B H,LI F,HAO Y L,YU Q. Heterogeneous oxidative desulfurization for model fuels using novel PW-coupled polyionic liquids w ith carbon chains of different lengths[J]. J Taiw an Inst Chem E,2017,76:83-88.
[6] LI H M,HE L N,LU J D,ZHU W S,JIANG X,WANG Y,YOU Y S. Deep oxidative desulfurization of fuels catalyzed by phosphotungstic acid in ionic liquids at room temperature[J]. Energy Fuels,2009,23:1354-1357.
[7] HU X F,LU Y K,DAI F N,LIU C G,LIU Y Q. Host-guest synthesis and encapsulation of phosphotungstic acid in MIL-101 via“bottle around ship”:An effective catalyst for oxidative desulfurization[J]. M icroporous M esoporous M ater,2013,170:36-44.
[8] ZHENG J J,JIAO Z B. Modified Bi2WO6w ith metal-organic framew orks for enhanced photocatalytic activity under visible light[J]. J Colloid Interf Sci,2017,488:234-239.
[9] DING J W,WANG R. A new green system of HPW@MOFs catalyzed desulfurization using O2as oxidant[J]. Chin Chem Lett,2016,27(5):655-658.
[10] CHEN M,YAN J Q,TAN Y,LI Y F,WU Z M,PAN L S,LIU Y J. Hydroxyalkylation of phenol with formaldehyde to bisphenol F catalyzed by Keggin phosphotungstic acid encapsulated in metal-organic framew orks M IL-100(Fe or Cr)and M IL-101(Fe or Cr)[J]. Ind Eng Chem Res,2015,54(47):11804-11813.
[11] ZHOU Z Y,CHENG B H,MA C,XU F,XIAO J,XIA Q B,LI Z. Flexible and mechanically-stable MIL-101(Cr)@PFs for efficient benzene vapor and CO2adsorption[J]. RSC Adv,2015,5(114):94276-94282.
[12] YANG X,LIU J,FAN K,RONG L. Hydrocracking of jatropha oil over non-sulfided PTA-NiMo/ZSM-5 catalyst[J]. Sci Rep,2017,7:41654.
[13] WAN H,CHEN C,WU Z W,QUE Y G,FENG Y,WANG W,WANG L,GUAN G F,LIU X Q. Encapsulation of heteropolyanion-based ionic liquid w ithin the metal-organic framew ork M IL-100(Fe)for biodiesel production[J]. ChemCatChem,2015,7(3):441-449.
[14] ZHU Y F,ZHU M Y,KANG L H,YU F,DAI B. Phosphotungstic acid supported on mesoporous graphitic carbon nitride as catalyst for oxidative desulfurization of fuel[J]. Ind Eng Chem Res,2015,54(7):2040-2047.