Comparative study of higher alcohols synthesis over alumina and activated carbon-supported alkali-modified MoS₂ catalysts promoted with group VIII metals

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• 作者：Venkateswara Rao Surisetty ; I. Eswaramoorthi ; A.K. Dalai ; ^{ajay.dalai@usask.ca}
• 关键词：AC ; activated carbon ; TPR ; temperature programmed reduction ; GHSV ; gas hourly space velocity ; ICP-MS ; inductively coupled plasma-mass spectroscopy ; XRD ; X-ray diffraction ; DRIFTS ; diffuse reflectance infrared Fourier transform spectroscopy ; STY ; space tim
• 刊名：Fuel
• 出版年：2012
• 期刊代码：33_00162361
• 类别：ce
• 出版时间：June, 2012
• 卷：96
• 期：Complete
• 页码：77-84
• 文件大小：1457 K

摘要

Potassium modified molybdenum sulfide catalysts promoted with nickel, cobalt, and rhodium were prepared using alumina or activated carbon as support to obtain highly dispersed MoS₂-based catalysts for higher alcohols synthesis. The N₂ adsorption study indicates a fall in textural characteristics of the catalysts compared to pure supports and this effect is more pronounced in activated carbon-based catalysts. The XRD phase analysis indicated the existence of promoted and un-promoted MoS₂ phases. The addition of rhodium resulted in an enhanced dispersion of smaller sized Mo particles. The TPR studies revealed that the addition of promoters such as, Ni, Co, and Rh improved the reducibility of the catalyst and shifts the reduction temperature of Mo⁺⁶ to lower temperature. Rh-promoted MoS₂ sites were revealed from DRIFT study of adsorbed CO over the Rh-promoted catalysts. Raman spectroscopy revealed the formation of Ni-Mo-S and Co-Mo-S phases in Ni and Co-promoted MoS₂ catalysts. The performance of these catalysts was tested for higher alcohols synthesis under similar conditions at 320 掳C, 8.3 MPa (1200 psi g) and 3.6 m³ (STP)/(kg of cat./h) and H₂ to CO molar ratio of 1. The Ni-promoted catalyst showed activity towards the formation of hydrocarbons over that of alcohols. The addition of Co to the Ni-Mo-K/Al₂O₃ catalyst improved the activity towards the formation of alcohols and hydrocarbons. The activity of Rh-promoted catalysts for higher alcohol synthesis was much higher than that obtained over the rhodium-free catalysts. The total alcohols space time yield and higher alcohols selectivities are significantly higher over the catalysts supported on activated carbon supported catalysts.