Thesis
Direct conversion of ethanol to isobutene on Zn[subscript x]Zr[subscript y]O[subscript z] mixed oxides: identification of active sites
Washington State University
Master of Science (MS), Washington State University
2013
Handle:
https://hdl.handle.net/2376/102012
Abstract
With increased availability and reduced cost of bioethanol conversion of this particular bio-based feedstock to highly valuable fuels and chemicals has been an especially important research goal. We have recently reported a mixed ZnxZryOz oxide catalyst with balanced acid/base sites capable of converting ethanol to isobutene in one continuous process. While conversion of ethanol to acetone and its subsequent conversion to products such as isobutene have been investigated separately by other groups, ZnxZryOz possesses the unique capability of carrying out both reactions in tandem with reported yields as high as 83% coupled with improved stability. In this work, the role of strength of Brønsted acidity in the ZnxZryOz catalysts in selectivity towards isobutene and stability against coke formation were elucidated using IRpyridine. Additionally, reaction and process parameters such as temperature, ethanol partial pressure, and steam to carbon ratios were studied with the goal of increasing that amount of ethanol fed from 0.6 mol% to more industrially relevant conditions. XRD, TEM, TPO, IR analysis of adsorbed Py (IR-Py), and nitrogen BET were used to characterize the catalyst and correlate the physical/chemical properties with catalytic performances. It was found that weak Brønsted sites correlated most strongly with catalyst activity and yield towards Isobutene, while strong Brønsted sites correlated most strong with coke formation. Additionally, the partial pressure of ethanol fed was increased to 8.3 mol% by using Zn1Zr8Oz mixed oxide catalyst calcined at 550 oC for 20 hours and reacted at 475 oC with a steam to carbon ratio of 2.5 and a residence time of 1.92 s·g·STP mL-1 .
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Details
- Title
- Direct conversion of ethanol to isobutene on Zn[subscript x]Zr[subscript y]O[subscript z] mixed oxides
- Creators
- Colin D. Smith
- Contributors
- Yong Wang (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Chemical Engineering and Bioengineering, School of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; [Pullman, Washington] :
- Identifiers
- 99900525153301842
- Language
- English
- Resource Type
- Thesis