274501 Co-Processing of Methane and Higher Alkanes in a Staged Autothermal Reactor

Wednesday, October 31, 2012: 10:10 AM
315 (Convention Center )
Samuel Blass, Aditya Bhan and Lanny D. Schmidt, Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN

Staged autothermal reactors have previously been shown to enable ethanol and methanol dehydration reactions to occur at 100 milliseconds or less without a need for external heat input [1-2]. We aim to extend the staged autothermal reactor concept to hydrocracking and hydroisomerization of higher hydrocarbons. A reactor was fabricated containing a 0.5 wt % Pt/γ-Al2O3 stage mixed with 10 g of either H-BEA, HZSM-5, or USY and situated downstream of a 1 wt % Rh - 1 wt % Ce /α-Al2O3 stage.  CH4, fed upstream to the Rh-Ce stage, formed oxidation products H2, CO, CO2, and H2O and released energy that heated the downstream zeolite stage. Hexane, decane, and 2-decanone were fed to the reactor between the two stages to avoid undesired oxidation reactions on the Rh-Ce stage.  Temperatures were changed by varying the separation distance between the stages.  Conversion of decane over USY and HBEA was approximately twice as high as the conversion over HZSM-5 from 300 °C to 460 °C.  The 12-member ring pore size of HBEA and USY reduces diffusion limitations of reactant molecules traveling through to an acid site leading to an increase in conversion [3]. The selectivity of aromatics formed from 2-decanone increased from 5% at 300 °C to 25% at 460 °C over HZSM-5.  Aromatic formation may be promoted by an increased initial propene selectivity formed by 2-decanone hydroprocessing.  At high conversions, more propene is consumed to form aromatics. Over all zeolites studied, selectivity of C5-6  compounds decreased with conversion while C2-3 compounds increased, indicating a series reaction was occurring. C5-6 products form first from decane and are then further decomposed.  The increase in yield of C5+ products and the presence of branched isomers indicates the feasibility of integrating a hydroprocessing catalyst with a partial oxidation catalyst in a single-pipe autothermal reactor.

1M.J. Skinner, E.L. Michor, W. Fan, M. Tsapatsis, A. Bhan, and L.D. Schmidt. ChemSusChem  4 (2011) 1151-1156.

2H. Sun and L.D. Schmidt. Applied Catalysis A, General 404 (2011) 81-86.

3Z. Wang, A. Kamo, T. Yoneda, T. Komatsu, T. Yashima. Applied Catalysis A, General 159 (1997) 119-132


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