Dissertation
Catalytic Conversion of Ethanol over Promoted Mixed Oxides
Washington State University
Doctor of Philosophy (PhD), Washington State University
12/2019
DOI:
https://doi.org/10.7273/000005552
Abstract
Developing renewable pathways to replace petroleum-derived chemicals and products has become increasingly urgent. With a diminishing role as a fuel additive, ethanol has instead greater value as a versatile platform chemical that can be derived from a wide range of carbon sources. One of the most promising ethanol transformations is the Guerbet reaction, a multi-step reaction that allows facile C-C coupling of shorter chain alcohols into longer chain alcohols such as 1-butanol and 2-ethylhexanol, which sees numerous usages as chemicals and fuels. Recent work has seen development of numerous multi-functional catalytic approaches, but the tendency toward side reactions and cross condensation of intermediate products means that achieving both high selectivity and conversion remains challenging and prevents commercial application of this process. In this dissertation, we present our development of an economically viable catalytic system based on copper promoted mixed oxide catalysts capable of transforming ethanol to higher alcohols in high yield.We report here a highly selective approach to producing 1-butanol and higher alcohols over low copper doped MgAl hydrotalcite catalyst. In-operando characterization demonstrates that at these low concentrations, copper remains atomically disperse and is stabilized as Cu+1 sites, in contrast to higher copper formulations that resulted in in-situ reduction to metallic Cu0 clusters. This change in copper speciation and dispersion corresponded to a stark change in the reaction data as well, where copper clustering was correlated to unselective formation of esters and ketones side products. This work demonstrated for the first time Guerbet condensation to higher alcohols with a selectivity over 80% at high conversions (>65%). Optimization of reaction conditions under high H2 partial pressures mitigated the primary deactivation mechanism, leading to extended catalyst lifetimes. Further improvements to catalytic performance were achieved by improving stability of the disperse copper sites through physical and chemical modifications of the support. Finally, the industrial viability of this catalytic system was demonstrated through a technoeconomic evaluation of an ethanol to 1-butanol process, with a minimum estimated butanol selling price that is cost competitive with the current 1-butanol market.
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Details
- Title
- Catalytic Conversion of Ethanol over Promoted Mixed Oxides
- Creators
- Mond F. Guo
- Contributors
- Xiao Zhang (Chair)Birgitte Ahring (Committee Member) - Washington State University, Chemical Engineering and Bioengineering, School ofSu Ha (Committee Member) - Washington State University, Chemical Engineering and Bioengineering, School ofKarthikeyan K Ramasamy (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Chemical Engineering and Bioengineering, School of
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Publisher
- Washington State University
- Number of pages
- 161
- Identifiers
- 99901054232901842
- Language
- English
- Resource Type
- Dissertation