丙烯直接气相环氧化反应中原料气组成优化的研究
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摘要
针对丙烯直接环氧化过程中原料气组成存在的问题,即大量稀释气以及O_2无法完全转化,通过计算无稀释气条件下O_2、 H_2和C_3H_6混合气体的爆炸限数据,得出O_2体积含量的安全范围(≤10%),移除了稀释气;通过考察了O_2体积含量及H_2/C_3H_6体积比对反应的影响,确定最优原料气组成为H_2/O_2/C_3H_6=62%/7%/31%,使O_2在反应过程中全部转化。并在此基础上研究了温度、压力和空速对反应的影响,探究了催化剂失活的原因。
Aiming at the problems existing in composition of feeding gas for the process of direct epoxidation of propene, namely, the big percentage of N_2 and incomplete conversion of O_2, by calculating the explosive limits of O_2, H_2 and C_3H_6, safety O_2 volumetric content(≤10%) has been found and the diluent gas has been removed. By investigating the influences exerted by O_2 content and H_2/C_3H_6 ratio on the process, the optimal composition of feeding gas has been acquired, i.e. H_2/O_2/C_3H_6=62%/7%/31%, so as to completely utilize O_2 during the process. The influences of reaction conditions and reasons that cause deactivation have also been investigated.
Aiming at the problems existing in composition of feeding gas for the process of direct epoxidation of propene, namely, the big percentage of N_2 and incomplete conversion of O_2, by calculating the explosive limits of O_2, H_2 and C_3H_6, safety O_2 volumetric content(≤10%) has been found and the diluent gas has been removed. By investigating the influences exerted by O_2 content and H_2/C_3H_6 ratio on the process, the optimal composition of feeding gas has been acquired, i.e. H_2/O_2/C_3H_6=62%/7%/31%, so as to completely utilize O_2 during the process. The influences of reaction conditions and reasons that cause deactivation have also been investigated.
引文
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[31] FENG X,DUAN X,QIAN G,et al.Au nanoparticles deposited on the external surfaces of TS-1:Enhanced stability and activity for direct propylene epoxidation with H-2 and O-2[J].Appl Catal B,2014,150:396-401.
[2] UPHADE B S,YAMADA Y,AKITA T,et al.Synthesis and characterization of Ti-MCM-41 and vapor-phase epoxidation of propylene using H-2 and O-2 over Au/Ti-MCM-41[J].Appl Catal,A,2001,215(1-2):137-148.
[3] JIN F,LIN T H,CHANG C C,et al.Gold supported on Ti incorporated MCM-36 as efficient catalysts in propylene epoxidation with H-2 and O-2[J].Rsc Advances,2015,5(76):61710-61718.
[4] UPHADE B S,AKITA T,NAKAMURA T,et al.Vapor-phase epoxidation of propene using H-2 and O-2 over Au/Ti-MCM-48[J].J Catal,2002,209(2):331-340.
[5] LIU C H,GUAN Y J,HENSEN E J M,et al.Au/TiO2@SBA-15 nanocomposites as catalysts for direct propylene epoxidation with O-2 and H-2 mixtures[J].J Catal,2011,282(1):94-102.
[6] LU J Q,ZHANG X M,BRAVO-SUAREZ J J,et al.Direct propylene epoxidation over/barium-promoted Au/Ti-TUD catalysts with H-2 and O-2:Effect of Au particle size[J].J Catal,2007,250(2):350-359.
[7] LEE W S,LAI L C,AKATAY M C,et al.Probing the gold active sites in Au/TS-1 for gas-phase epoxidation of propylene in the presence of hydrogen and oxygen[J].J Catal,2012,296:31-42.
[8] HUANG J H,TAKEI T,AKITA T,et al.Gold clusters supported on alkaline treated TS-1 for highly efficient propene epoxidation with O-2 and H-2[J].Appl Catal B,2010,95(3-4):430-438.
[9] FENG X,DUAN X,YANG J,et al.Au/uncalcined TS-1 catalysts for direct propene epoxidation with H-2 and O-2:Effects of Si/Ti molar ratio and Au loading[J].Chem Eng J,2015,278:234-239.
[10] FENG X,LIU Y,LI Y,et al.Au/TS-1 catalyst for propene epoxidation with H-2/O-2:A novel strategy to enhance stability by tuning charging sequence[J].AlChE J,2016,62(11):3963-3972.
[11] FENG X,SHENG N,LIU Y,et al.Simultaneously enhanced stability and selectivity for propene epoxidation with H-2 and O-2 on Au catalysts supported on nano-crystalline mesoporous TS-1[J].Acs Catalysis,2017,7(4):2668-2675.
[12] LI Z,WANG Y,ZHANG J,et al.Better performance for gas-phase epoxidation of propylene using H-2 and O-2 at lower temperature over Au/TS-1 catalyst[J].Catal Commun,2017,90:87-90.
[13] LEE W S,AKATAY M C,STACH E A,et al.Enhanced reaction rate for gas-phase epoxidation of propylene using H-2 and O-2 by Cs promotion of Au/TS-1[J].J Catal,2013,308:98-113.
[14] HUANG J H,LIMA E,AKITA T,et al.Propene epoxidation with O-2 and H-2:Identification of the most active gold clusters[J].J Catal,2011,278(1):8-15.
[15] GAUDET J,BANDO K K,SONG Z X,et al.Effect of gold oxidation state on the epoxidation and hydrogenation of propylene on Au/TS-1[J].J Catal,2011,280(1):40-49.
[16] QI C X,HUANG J H,BAO S Q,et al.Switching of reactions between hydrogenation and epoxidation of propene over Au/Ti-based oxides in the presence of H-2 and O-2[J].J Catal,2011,281(1):12-20.
[17] TAYLOR B,LAUTERBACH J,DELGASS W N.The effect of mesoporous scale defects on the activity of Au/TS-1 for the epoxidation of propylene[J].Catal Today,2007,123(1-4):50-58.
[18] FENG X,DUAN X,CHENG H,et al.Au/TS-1 catalyst prepared by deposition-precipitation method for propene epoxidation with H-2/O-2:Insights into the effects of slurry aging time and Si/Ti molar ratio[J].J Catal,2015,325:128-135.
[19] FENG X,CHEN D,ZHOU X G.Thermal stability of TPA template and size-dependent selectivity of uncalcined TS-1 supported Au catalyst for propene epoxidation with H-2 and O-2[J].Rsc Advances,2016,6(50):44050-44056.
[20] LIU Y W,ZHANG X M,SUO J S.Gold supported on nitrogen-incorporated TS-1 for gas-phase epoxidation of propylene[J].Chinese Journal of Catalysis,2013,34(2):336-340.
[21] STANGLAND E E,TAYLOR B,ANDRES R P,et al.Direct vapor phase propylene epoxidation over deposition-precipitation gold-titania catalysts in the presence of H-2/O-2:Effects of support,neutralizing agent,and pretreatment[J].J Phys Chem B,2005,109(6):2321-2330.
[22] YAP N,ANDRES R P,DELGASS W N.Reactivity and stability of Au in and on TS-1 for epoxidation of propylene with H-2 and O-2[J].J Catal,2004,226(1):156-170.
[23] XU L,REN Y J,WU H H,et al.Core/shell-structured TS-1@mesoporous silica-supported Au nanoparticles for selective epoxidation of propylene with H-2 and O-2[J].J Mater Chem,2011,21(29):10852-10858.
[24] SERRANO D P,SANZ R,PIZARRO P,et al.Hierarchical TS-1 zeolite as an efficient catalyst for oxidative desulphurization of hydrocarbon fractions[J].Appl Catal B,2014,146:36-42.
[25] WANG Z D,XU L,JIANG J G,et al.One-pot synthesis of catalytically active and mechanically robust mesoporous TS-1 microspheres with the aid of triblock copolymer[J].Microporous Mesoporous Mater,2012,156:106-114.
[26] DUPREY E,BEAUNIER P,SPRINGUELHUET M A,et al.Characterization of catalysts based on titanium silicalite,TS-1,by physicochemical techniques[J].J Catal,1997,165(1):22-32.
[27] CROWL D A,LOUVAR J F.Chemical Process Safety:Fundamentals with Applications[M].New Jersey,Prentice Hall,2007.
[28] Holtappels K,Schroeder V.Explosion characteristics of hydrogen-oxygen and hydrogen-air mixtures at elevated temperatures and pressures[C].Madrid:Proceedings of the 2nd European Hydrogen Energy Conference,November,2005.
[29] JOHN D,HANSEL J G,TOM P.Influence of temperature on flammability limits of heat treating atmosphere[J].Heat Treat Met,2011,36(10):106-108.
[30] SCHILDBERG H P,AKTIENGESELLSCHAFT B,GCT/S-L.Explosion characteristics of Propene/O2/N2 at 1,5,10 and 30 bar abs,25 ℃ and 200 ℃[C].Nurnberg:International ESMG Symposium,2005.
[31] FENG X,DUAN X,QIAN G,et al.Au nanoparticles deposited on the external surfaces of TS-1:Enhanced stability and activity for direct propylene epoxidation with H-2 and O-2[J].Appl Catal B,2014,150:396-401.