Al_2O_3晶型对K_2WO_4/Al_2O_3物化性质及催化合成甲硫醇的影响
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摘要
采用等体积浸渍法改性制备了K_2WO_4/Al_2O_3催化剂,研究了载体Al_2O_3晶型对K_2WO_4/Al_2O_3催化剂物化性质及催化合成甲硫醇的影响。借助XRD、SEM、EDS、BET及NH_3/CO_2-TPD等手段对不同催化剂的晶相组成、微观形貌、孔结构及表面酸碱性质进行了表征分析。结果表明,Al_2O_3晶型对K_2WO_4/Al_2O_3催化剂晶相组成及微观形貌影响较小,但对孔结构及表面酸碱性质影响较大。与K_2WO_4/η-Al_2O_3和K_2WO_4/θ-Al_2O_3催化剂相比,K_2WO_4/γ-Al_2O_3催化剂具有更大比表面积及孔容(介孔比表面积为226. 75 m~2·g~(-1),总孔容为0. 557 cm~3·g~(-1)),且表面仅有弱酸和弱碱中心(弱酸浓度为0. 42521 mmol·g~(-1),弱碱浓度为0. 44184 mmol·g~(-1))。在反应温度370℃,反应压力1. 0 MPa,H_2S流速4. 9 mL·min~(-1),CH_3OH流速0. 03 mL·min~(-1)反应条件下,K_2WO_4/γ-Al_2O_3催化剂表现出优良催化性能,甲醇转化率和甲硫醇选择性分别达81. 58%和87. 05%,与K_2WO_4/η-Al_2O_3和K_2WO_4/θ-Al_2O_3催化剂相比,甲醇转化率分别提高了4. 23%和19. 42%,甲硫醇选择性分别提高了14. 68%和7. 85%。
The effect of various of Al_2O_3 polymorphs as a support respectively on the physicochemical properties and catalytic performance of K_2WO_4/Al_2O_3 catalysts prepared via equal volume impregnation method was studied in this paper. The crystal phase composition,microstructure,pore structure,surface acidity and alkalinity of different catalysts were characterized by XRD,SEM,EDS,BET and NH_3/CO_2-TPD techniques. The results showed that various Al_2O_3 polymorphs had little effect on the crystal phase composition and morphology of K_2WO_4/Al_2O_3 catalyst,but posed great impact on the pore structure and surface acidity and alkalinity. Compared with K_2WO_4/η-Al_2O_3 and K_2WO_4/θ-Al_2O_3 catalysts,K_2WO_4/γ-Al_2O_3 catalyst had larger specific surface area and pore volume( medium specific surface area is 226. 75 m~2·g~(-1),total pore volume is 0. 557 cm~3·g~(-1)),and only weak acid and weak base centers existed on the surface( weak acid concentration is 0. 42521 mmol·g~(-1),weak base concentration is 0. 44184 mmol·g~(-1)). Accordingly,the methanol conversion and methanethiol selectivity were reach to 81. 58% and 87. 05% respectively under the condition of reaction temperature of 370 ℃,reaction pressure of 1.0 MPa,H_2S flow rate of 4. 9 mL·min~(-1),and CH_3OH flow rate of 0. 03 mL·min~(-1). Compared with K_2WO_4/η-Al_2O_3 and K_2WO_4/θ-Al_2O_3 catalysts,the methanol conversion increased by 4. 23% and 19. 42%,and the methanethiol selectivity increased by 14. 68% and 7. 85%,respectively.
The effect of various of Al_2O_3 polymorphs as a support respectively on the physicochemical properties and catalytic performance of K_2WO_4/Al_2O_3 catalysts prepared via equal volume impregnation method was studied in this paper. The crystal phase composition,microstructure,pore structure,surface acidity and alkalinity of different catalysts were characterized by XRD,SEM,EDS,BET and NH_3/CO_2-TPD techniques. The results showed that various Al_2O_3 polymorphs had little effect on the crystal phase composition and morphology of K_2WO_4/Al_2O_3 catalyst,but posed great impact on the pore structure and surface acidity and alkalinity. Compared with K_2WO_4/η-Al_2O_3 and K_2WO_4/θ-Al_2O_3 catalysts,K_2WO_4/γ-Al_2O_3 catalyst had larger specific surface area and pore volume( medium specific surface area is 226. 75 m~2·g~(-1),total pore volume is 0. 557 cm~3·g~(-1)),and only weak acid and weak base centers existed on the surface( weak acid concentration is 0. 42521 mmol·g~(-1),weak base concentration is 0. 44184 mmol·g~(-1)). Accordingly,the methanol conversion and methanethiol selectivity were reach to 81. 58% and 87. 05% respectively under the condition of reaction temperature of 370 ℃,reaction pressure of 1.0 MPa,H_2S flow rate of 4. 9 mL·min~(-1),and CH_3OH flow rate of 0. 03 mL·min~(-1). Compared with K_2WO_4/η-Al_2O_3 and K_2WO_4/θ-Al_2O_3 catalysts,the methanol conversion increased by 4. 23% and 19. 42%,and the methanethiol selectivity increased by 14. 68% and 7. 85%,respectively.
引文
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[17]杨意泉,王琪,戴深峻,等.高硫合成气制甲硫醇钼硫基催化剂的制备[J].应用化学,1999,7(4):47-51.
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[19] Mashkin V Y. Kinetic study of dimethylsulfide and methanethiol synthesis[J]. Applied Catalysis A General,1994,109(1):45-61.
[20] Ziolek M,Czyzniewska J,Lamotte J,et al. Reactions of alcohols with hydrogen sulfide on zeolites. Part 6:FT,i. r. spectroscopy investigation of the reaction between methanol and hydrogen sulfide on Na X and Na Y[J]. Zeolites,1996,16(1):42-49.
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[22] Anna V Mashkina. Heterogeneous catalytic synthesis of alkanethiols and dialkyl sulfides from alcohols and hydrogen sulfide[J]. Russian Chemical Reviews,1995,64(64):1131.
[23]张继光.催化剂制备过程技术[M].北京:中国石化出版社,2004:28-32.
[24]朱洪法.催化剂载体制备及应用技术[M].北京:石油工业出版社,2002:210-213.
[25] Ziolek M,Kujawa J,Saur O. Mental Oxides as Catalysts for the Reaction between Methanol and Hydrogen Sulfide[J]. Phys. Chem,1993,97,9761-9766.
[26]高洪宾主编.有机化学(第四版)[M].北京:高等教育出版社,2007:82-84.
[2]胡宝龙. 2010年蛋氨酸市场回顾及2011年市场展望[J].饲料广角,2011(3):15-17.
[3]徐子成,周荣才.农药灭多威和硫双威[J].上海化工,1994(1):6-8.
[4]常俊石,于海斌,姜雪丹,等.国内甲硫醇催化剂现状[J].工业催化,2005,13(6):32-36.
[5] Sauer J,Boeck W,Von Hippel L,et al. Catalyst,process for its preparation,and use for synthesis of methyl mercaptan:US,US5852219[P].1998.
[6]李培彬.甲硫醇的生产、应用与发展[J].精细与专用化学品,2005,13(12):5-6.
[7]孙玉泉,王亚宁.甲硫醇的应用与合成[J].天津化工,2002(3):23-24.
[8]陈振锋,卢军.含硫香料———硫代香茅醇,硫代芳樟醇的合成研究[J].化工技术与开发,1998(1):11-15.
[9] Takagi K. Synthesis of aromatic thiols from aryl iodides and thiourea by means of nickel catalyst[J]. Chemistry Letters,1985(9):1307-1308.
[10] A. H.勃拉特主编,南京大学化学系有机化学教研组译.有机合成(第二版)[M].北京:科学出版,1964:145-155.
[11]钱佐国,孙明昆,周曾昊,等.合成甲硫醇的一种改进方法[J].青岛海洋大学学报,1995,25(3):327-330.
[12] Gutiérrez O Y,Kaufmann C,Lercher J A. Synthesis of Methanethiol from Carbonyl Sulfide and Carbon Disulfide on(Co)K-Promoted Sulfide Mo/SiO2Catalysts[J]. Acs Catalysis,2011,1(11):1595.
[13] Chen A,Wang Q,Li Q,et al. Direct synthesis of methanethiol from H2S-rich syngas over sulfided Mo-based catalysts[J]. Journal of Molecular Catalysis A Chemical,2008,283(1):69-76.
[14] Zhang Y,Chen S,Wu M,et al. Promoting effect of SiO2,on the K2WO4/Al2O3,catalysts for methanethiol synthesis from methanol and H2S[J]. Catalysis Communications,2012,22(18):48-51.
[15] Baojian Zhang,Stuart H. Taylor,Graham J. Hutchings. Catalytic synthesis of methanethiol from CO/H2/H2S mixtures usingα-Al2O3[J]. New Journal of Chemistry,2004,28(4):471-476.
[16]张元华,袁成龙,陈世萍,等.磷助剂对K2WO4/Al2O3催化合成甲硫醇的影响[J].石油化工,2012,41(12):1357-1362.
[17]杨意泉,王琪,戴深峻,等.高硫合成气制甲硫醇钼硫基催化剂的制备[J].应用化学,1999,7(4):47-51.
[18] Mashkina A. V.,Heterogeneous Catalytic Synthesis of Alkanethiols and Dialkyl Sulfides from Alcohols and Hydrogen Sulfide,1995,64:1131-1147.
[19] Mashkin V Y. Kinetic study of dimethylsulfide and methanethiol synthesis[J]. Applied Catalysis A General,1994,109(1):45-61.
[20] Ziolek M,Czyzniewska J,Lamotte J,et al. Reactions of alcohols with hydrogen sulfide on zeolites. Part 6:FT,i. r. spectroscopy investigation of the reaction between methanol and hydrogen sulfide on Na X and Na Y[J]. Zeolites,1996,16(1):42-49.
[21] Ziolek M,Czyzniewska J,Kujawa J,et al. Reactions of alcohols with hydrogen sulphide on zeolites. Part 7:the effect of Brǒnsted acidity of faujasite type zeolites on methanol hydrosulphurisation[J]. Microporous&Mesoporous Materials,1998,23(1-2):45-54.
[22] Anna V Mashkina. Heterogeneous catalytic synthesis of alkanethiols and dialkyl sulfides from alcohols and hydrogen sulfide[J]. Russian Chemical Reviews,1995,64(64):1131.
[23]张继光.催化剂制备过程技术[M].北京:中国石化出版社,2004:28-32.
[24]朱洪法.催化剂载体制备及应用技术[M].北京:石油工业出版社,2002:210-213.
[25] Ziolek M,Kujawa J,Saur O. Mental Oxides as Catalysts for the Reaction between Methanol and Hydrogen Sulfide[J]. Phys. Chem,1993,97,9761-9766.
[26]高洪宾主编.有机化学(第四版)[M].北京:高等教育出版社,2007:82-84.