Carbon Monoxide Hydrogenation over Zirconia Supported Ni and Co-Ni Bimetallic Catalysts
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Catalysis Letters Vol. 98, Nos. 2–3, November 2004 (Ó 2004)
Carbon monoxide hydrogenation over zirconia supported Ni and Co–Ni bimetallic catalysts Paresh C. Das1, Naraan C. Pradhan1,2, Ajay K. Dalai1* and Narendra N. Bakshi1 1
Catalysis and Chemical Reaction Engineering Laboratories, Department of Chemical Engineering, University of askatchewan, Saskatoon SK S7N 5C5, Canada 2 Permanent address: Department of Chemical Engineering, Indian Institute of Technology, Kharagpur, 721 302, India
Received 22 April 2004; accepted 9 August 2004
Zirconia supported nickel and cobalt–nickel bimetallic catalysts were prepared and characterized for various physico-chemical properties. The hydrogenation of carbon monoxide was studied over these catalysts in the pressure range of 101.3–1654 kPa, temperature range of 513–533 K, weight hourly space velocity range of 8–14 h1 and H2/CO mole ratio of 2. Catalysts containing both Co and Ni were found to give higher C5þ hydrocarbons selectivity compared to that containing only Ni. A maximum C5þ hydrocarbons selectivity of 55 wt% was obtained at 655 kPa pressure, 523 K and 9.6 h1 of WHSV with catalyst containing 4.03 wt% Co and 2.64 wt% Ni. The C2 and C3 olefin contents of the products decreased with increase in pressure. Improved deactivation behavior of the catalysts was observed when operated at high pressure. KEY WORDS: Fisher–Tropsch synthesis; CO hydrogenation; bimetallic catalyst; nickel; cobalt; zirconia support.
1. Introduction Petroleum is the major source of gasoline and diesel, the most preferred fuels for the transportation industry. Gradual depletion of petroleum reserves has created interest in finding alternative sources of energy. With the present reserves, natural gas and coal will continue to play a dominating role in the future energy scenario of the world [1]. These materials are very useful for the production of transportation fuels such as gasoline and diesel by Fischer–Tropsch (FT) synthesis. The increasing importance of FT synthesis can also be realized since the legislative pressure on the maximum level of sulfur and nitrogen emissions from automotive engines is increasing at a faster rate. The diesel and gasoline produced through FT synthesis are of much better quality in terms of sulfur and nitrogen concentrations to meet the future environmental standards. Thus, the FT synthesis perhaps could be the most promising solution for converting non-petroleum based carbonaceous materials to cleaner transportation fuels. However, a major drawback of the process is the low selectivities for gasoline and diesel products. It has been reported that bimetallic catalysts containing Ni, Fe, Co and Ru are more active towards CO conversion, and exhibit markedly improved selectivity for olefins and heavier hydrocarbons as compared to single metal catalysts [2–7]. A large number of combinations of bimetallic catalysts are possible from the above four *To whom correspondence should be addressed. E-mail: [email protected]
metals by varying the supports such as silica, alumina,
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