Journal of Industrial and Engineering Chemistry, Vol.16, No.6, 923-928, November, 2010
Effect of promoter in the oxidative coupling of methane over synthesized Mn/SiO2 nanocatalysts via incipient wetness impregnation
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The M-Na-Mn/SiO2 nanocatalysts (M =W, Mo, Nb, V, Cr) were synthesized with the size of 12-92 nm by incipient wetness impregnation method to study the effect of different promoters on the catalytic performance in the oxidative coupling of methane. The results at 1 atm, 1048 K, 2500 ml h^(-1) g^(-1), and CH4/O2/N2 = 2/2/1 revealed that C2 selectivity was significantly increased (31.6%) in the order of W> Mo > Nb > Cr > V whereas moderate enhancement (12.6%) was observed in the CH4 conversion in the order of W> Cr > Nb > Mo > V. The results of the characterization techniques (Raman, FT-IR, BET, TGA/DTA and XRD) demonstrated that Mn2O3 and a-cristobalite were the predominant species and active sites in the nanocatalyst surface and Na2MoO4, Na2WO4 and Mn2O3 crystalline phases contributed to achieving high selectivity of C2 products. The redox mechanism involving two metal sites such as Mn^(3+/2+) and W^(6+/5+) or Mn^(3+/2+) and Mo^(6+/5+) was found to be the most compatible route with the OCM reaction path in which CH4 and O2 adsorption was the controlling step.
Keywords:Oxidative coupling of methane (OCM);Incipient wetness impregnation;Nanocatalyst synthesis;Promoter;Active sites
- Kamali Shahri M, Alavi M, J. Nat. Gas Chem., 18, 25 (2009)
- Cho W, Kim YC, Kim SS, J. Ind. Eng. Chem., 16(1), 20 (2010)
- Talebizadeh A, Mortazavi Y, Khodadadi A, Fuel Process. Technol., 91, 503 (2009)
- Salehoun V, Khodadadi A, Mortazavi Y, Talebizadeh A, Chem. Eng. Sci., 63(20), 4910 (2008)
- Malekzadeh A, Dalai A, Khodadadi A, Mortazavi Y, Catal. Commun., 9, 960 (2008)
- Liu H, Yang D, Gao R, Chen L, Zhang S, Wang X, Catal. Commun., 9, 1302 (2008)
- Chua Y, Mohamed A, Bhatia S, Appl. Catal. A: Gen., 43, 3142 (2008)
- Wu JJ, Zhang HL, Qin S, Hu CW, Appl. Catal. A: Gen., 323, 126 (2007)
- Wu JJ, Qin S, Hu CW, Catal. Lett., 118(3-4), 285 (2007)
- Malekzadeh A, Khodadadi A, Dalai A, Abedini M, J. Nat. Gas Chem., 16, 121 (2007)
- Hou SC, Cao YA, Xiong W, Liu HC, Kou YA, Ind. Eng. Chem. Res., 45(21), 7077 (2006)
- Fang X, Li SL, Gu J, Yang JD, Chin. J. Mol. Catal., 6, 427 (1992)
- Ni Y, Peng W, Sun A, Mo W, Hu J, Li T, Li G, J. Ind. Eng. Chem., 16(4), 503 (2010)
- Kou YA, Wang HL, Zhang H, Yang XY, Catal. Today, 51(1), 47 (1999)
- Wang DJ, Rosynek MP, Lunsford JH, J. Catal., 155(2), 390 (1995)
- Ji SF, Xiao TC, Li SB, Xu CZ, Hou RL, Coleman KS, Green MLH, Appl. Catal. A: Gen., 225(1-2), 271 (2002)
- Palermo A, Vazquez JPH, Lee AF, Tikhov MS, Lambert RM, J. Catal., 177(2), 259 (1998)
- Utiyama M, Hattori H, Tanabe K, J. Catal., 53, 273 (1987)
- Ji SF, Xiao TC, Li SB, Chou LJ, Zhang B, Xu CZ, Hou RL, York APE, Green MLH, J. Catal., 220(1), 47 (2003)
- Buciuman F, Craciun R, Zahn D, Phys. Chem. Chem. Phys., 1, 185 (1999)
- Ziolek M, Sobczak I, Lewandowska A, Nowak I, Decyk P, Renn M, Jankowska B, Catal. Today, 70(1-3), 169 (2001)
- Resini C, Montanari T, Busca G, Jehng JM, Wachs IE, Catal. Today, 99(1-2), 105 (2005)
- Widjaja E, Sampanthar JT, Han XD, Goh E, Catal. Today, 131(1-4), 21 (2008)
- Klisinska A, Loridant S, Grzybowska B, Stoch J, Gressel I, Appl. Catal. A: Gen., 309(1), 17 (2006)
- Guerrero-Perez MO, Herrera MC, Malpartida I, Larrubia MA, Alemany LJ, Banares MA, Catal. Today, 126(1-2), 177 (2007)
- Yu ZQ, Yang XM, Lunsford JH, Rosynek MP, J. Catal., 154(1), 163 (1995)
- Lunsford J, PhD dissertation, Texas A&M University (1991)
- Hinson W, Bytyn W, Baerns M, Baerns M, Proc. 8th Int. Cong. Catal., vol. 3, Verlag Chemie, Weinheim, Germany (1984)
- Ito T, Wang J, Lin C, Lunsford J, J. Am. Chem. Soc., 107, 5062 (1985)