Thesis
Investigation into the catalytic H2 and CO2 reaction over potassium promoted cobalt-copper catalysts
Washington State University
Master of Science (MS), Washington State University
2018
Handle:
https://hdl.handle.net/2376/102281
Abstract
Recycling of anthropogenic CO2 emissions into transportation fuels and fuel additives has garnished increasing interest. As an additive, mixed alcohols boost the octane rating of gasoline and diesel in an environmentally friendly matter in comparison to other additives such as lead, aromatics and methyl tert-butyl ether. This thesis investigates the influence of a K-promoter on the activity and nature of CoCu catalysts aimed at facilitating the reaction of H2 and CO2 into higher alcohols. The findings demonstrate catalytic bimetallic CoCu particles contain partitioned metallic Co and Cu phases (both FCC crystal structure) co-existing within the same particle as determined via TEM/EDS measurements. A Co@Cu core-shell structure is not readily observed as originally hypothesized. XPS measurements further show that the surface of the bimetallic CoCu particles were cobalt rich with potassium readily present on the surface. Notably, the surface area of the CoCu particles decreased considerably with increasing K-loading. Increased presence of CoO was observed for K-containing CoCu particles prior to ("virgin") reaction as the loading of KNO3 increased in the parent CoCu oxalate precursor. This CoO phase was no longer present after the reaction. No cobalt carbide phase was observed via XRD measurements further debunking the original hypothesis that this phase was essential for chain lengthened products. Simple addition of a K-promoter to the CoCu system tuned selectivity from that of predominantly methane to linear hydrocarbons and alcohols as demonstrated using catalytic reactor tests. A clear trade-off between increasing K-loading and decreasing CO2 conversion (and TOF) was observed. In conclusion, I recommend that the interface of the Co and Cu phases in the presence of a K-promoter is necessary to obtain higher alcohols and hydrocarbons. Perhaps the presence of a CoO phase could also be interesting toward obtaining long hydrocarbons and alcohols. This work has developed an understanding of the influence of a K-promoter on the structure-activity relationship of CoCu catalysts. These findings are to be published in order to further advance scientific knowledge aimed at strategically designing future catalysts.
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Details
- Title
- Investigation into the catalytic H2 and CO2 reaction over potassium promoted cobalt-copper catalysts
- Creators
- Jenny Marie Voss
- Contributors
- Norbert Kruse (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
- 99900525149201842
- Language
- English
- Resource Type
- Thesis