Transport-enhanced. alpha. -olefin readsorption pathways in Ru-catalyzed hydrocarbon synthesis

Journal Article · Wed May 01 04:00:00 EDT 1991 · Journal of Catalysis; (USA)

DOI:https://doi.org/10.1016/0021-9517(91)90027-2· OSTI ID:5724914

Iglesia, E; Reyes, S C; Madon, R J ^[1]

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1. Exxon Research and Engineering Co., Annadale, NJ (USA)

Residence time and cofeed studies show that olefins and paraffins are primary products in Ru-catalyzed hydrocarbon synthesis. Olefins readsorb and initiate surface chains that are indistinguishable from those formed directly from CO/H{sub 2} and that continue to grow and ultimately desorb as high molecular weight hydrocarbons. Transport-enchanced {alpha}-olefin readsorption leads to an increase in chain growth probability ({alpha}) and in paraffin content with increasing pore and bed residence time. Deviations from conventional (Flory) polymerization kinetics and the increasing paraffinic content of higher hydrocarbons are quantitatively described by transport effects on the residence time of intermediate olefins, without requiring the presence of several types of chain growth sites. The transport-reaction model combines a description of diffusive and convective transport with a mechanistic kinetic model of olefin readsorption and of CO hydrogenation and chain growth. It quantitatively describes carbon number, site density, pellet size, and space velocity effects on hydrocarbon synthesis rate and product distribution. The model is consistant with the experimentally observed maximum C{sub 5+} selectivities at intermediate values of site density and pellet size. These intermediate values permit extensive readsorption of {alpha}-olefins without significant CO arrival transport limitations.

• OSTI ID: 5724914
• Journal Information: Journal of Catalysis; (USA), Journal Name: Journal of Catalysis; (USA) Vol. 129:1; ISSN 0021-9517; ISSN JCTLA
• Country of Publication: United States
• Language: English

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