Catalytic Conversion of Anisole: Evidence of Oxygen Removal in Reactions with Hydrogen
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Catalytic Conversion of Anisole: Evidence of Oxygen Removal in Reactions with Hydrogen Ron C. Runnebaum • Tarit Nimmanwudipong David E. Block • Bruce C. Gates
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Received: 23 September 2010 / Accepted: 18 November 2010 / Published online: 14 December 2010 Ó The Author(s) 2011. This article is published with open access at Springerlink.com
Abstract The conversion of anisole, a prototypical biooil compound, was catalyzed by Pt/Al2O3 in the presence of H2 at 573 K, with the selectivity for C–O bond breaking approximately matching that for ring hydrogenation; these reactions were accompanied by methyl group transfers matching those in the conversion catalyzed by HY zeolite. Keywords Anisole Zeolite Y Supported platinum Transalkylation Hydrodeoxygenation
and an aromatic ring. Reactions were catalyzed by a solid acid (HY zeolite, Zeolyst CBV 720) and separately by a catalyst consisting of a metal dispersed on an acidic support (Pt/Al2O3, Sigma–Aldrich, 1% wt Pt). The goal of the research was to develop detailed reaction networks, characterized by numerous connected pathways, for the conversion of anisole with catalysts representing these two important classes of catalysts.
2 Experimental 1 Introduction Plant biomass is a potentially valuable renewable source of fuels and chemicals. Lignocellulose can be rapidly transformed into liquids by pyrolysis, giving ‘‘bio-oil,’’ but the high oxygen content leads to immiscibility with fossil fuels, instability, and corrosion [1–3]. Bio-oils typically contain several hundred compounds [4, 5], and an understanding of the reaction networks in their catalytic upgrading is limited; even information characterizing the upgrading of individual bio-oil compounds is scarce [6– 10]. Our approach to begin unravelling this chemistry, and specifically to understand oxygen removal reactions, was to investigate the conversion of a bio-oil compound, anisole, chosen as a prototype because it has both an ether linkage R. C. Runnebaum T. Nimmanwudipong D. E. Block B. C. Gates (&) Department of Chemical Engineering and Materials Science, University of California, Davis, CA 95616, USA e-mail: [email protected] D. E. Block Department of Viticulture and Enology, University of California, Davis, CA 95616, USA
Catalytic reactions were carried out in a once-through packed-bed flow reactor under the following conditions, with liquid anisole (methoxybenzene, Sigma–Aldrich, 99.8%) vaporized into a flowing gas stream: catalyst mass 4.1–401.5 mg, temperature 573 K, pressure 140 kPa, anisole liquid flow rate 0.03 mL min-1, gas feed flow rate 100 mL min-1 (as pure N2 in experiments with HY zeolite and as 30% H2/70% N2 in experiments with Pt/Al2O3). Each catalyst powder was diluted with particles of inert, nonporous a-Al2O3. The product gas stream was condensed at 285–288 K. Uncondensed gases and condensate samples collected periodically were analyzed by gas chromatography and gas chromatography/mass spectrometry.
3 Results Dozens of products were observed in the conversions with each catalyst. S
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