Advanced search options

Advanced Search Options 🞨

Browse by author name (“Author name starts with…”).

Find ETDs with:

in
/  
in
/  
in
/  
in

Written in Published in Earliest date Latest date

Sorted by

Results per page:

Sorted by: relevance · author · university · dateNew search

You searched for subject:(ketonization). Showing records 1 – 3 of 3 total matches.

Search Limiters

Last 2 Years | English Only

No search limiters apply to these results.

▼ Search Limiters


University of Notre Dame

1. Gregory Thomas Neumann. Tailoring the Active Site and Mesostructure of ZSM-5 for Deoxygenation and C-C Bond Coupling Reactions</h1>.

Degree: PhD, Chemical Engineering, 2015, University of Notre Dame

Zeolites are a class of microporous, crystalline materials that have many applications as adsorbents, membranes, sensors, and catalysts. For use as a catalyst, zeolites can be synthesized with various acidities, micropore structures, bulk porosities, and heteroatom substitutions. Therefore zeolites can meet the demands for a wide variety of reactions, especially for reactions that use feed streams with varying compositions (e.g. biomass, petroleum, etc.). <pre><code> The use of lignocellulosic biomass as a source of renewable energy has gained traction in recent years due to the finite supply, environmental effects, geopolitics, and overall sustainability of fossil fuels. As the only source of renewable carbon on earth, biomass has been widely studied to meet the demands of a growing need for liquid renewable energy. Although non-catalytic, thermal conversion of solid lignocellulosic biomass to liquids can be achieved, the resulting product is often unstable, highly oxygenated, and subsequently a low quality fuel oil. With an appropriate catalyst, these products or reaction intermediates can be upgraded to valuable and stable fuels and chemicals mimicking those currently produced from petroleum resources. Thus, a catalyst is an essential part of the process of converting biomass to drop-in fuels and chemicals. This research addresses the innovative solutions to design and control zeolite catalyst properties to enhance the conversion of biomass feedstocks to value added chemicals and fuels. The results of altering the acidity, microporous structure, bulk porosity, and heteroatom substitution of ZSM-5 for biomass upgrading reactions are presented here. This first application of this work was the assessment of these various catalyst properties for the catalytic fast pyrolysis of lignin model compounds. It was determined that acidic, mesoporous, HZSM-5 was the most favorable catalyst for the production of aromatic liquid hydrocarbon fuels. The second application of this work was the synthesis of ZSM-5 with cerium incorporated within the framework. With detailed characterization and the use of well-studied model compound reactions, it was determined that cerium was indeed incorporated into the framework of the catalyst, yielding highly active sites to enhance the stability of oils derived from lignocellulosic biomass. </code></pre> Advisors/Committee Members: Dr. Prashant Kamat, Committee Member, Dr. Jason Hicks, Committee Chair, Dr. Ed Maginn, Committee Member, Dr. Paul McGinn, Committee Member.

Subjects/Keywords: zeolite; biomass; cerium; ketonization; catalytic fast pyrolysis

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Neumann, G. T. (2015). Tailoring the Active Site and Mesostructure of ZSM-5 for Deoxygenation and C-C Bond Coupling Reactions</h1>. (Doctoral Dissertation). University of Notre Dame. Retrieved from https://curate.nd.edu/show/qn59q239x0d

Chicago Manual of Style (16th Edition):

Neumann, Gregory Thomas. “Tailoring the Active Site and Mesostructure of ZSM-5 for Deoxygenation and C-C Bond Coupling Reactions</h1>.” 2015. Doctoral Dissertation, University of Notre Dame. Accessed December 16, 2018. https://curate.nd.edu/show/qn59q239x0d.

MLA Handbook (7th Edition):

Neumann, Gregory Thomas. “Tailoring the Active Site and Mesostructure of ZSM-5 for Deoxygenation and C-C Bond Coupling Reactions</h1>.” 2015. Web. 16 Dec 2018.

Vancouver:

Neumann GT. Tailoring the Active Site and Mesostructure of ZSM-5 for Deoxygenation and C-C Bond Coupling Reactions</h1>. [Internet] [Doctoral dissertation]. University of Notre Dame; 2015. [cited 2018 Dec 16]. Available from: https://curate.nd.edu/show/qn59q239x0d.

Council of Science Editors:

Neumann GT. Tailoring the Active Site and Mesostructure of ZSM-5 for Deoxygenation and C-C Bond Coupling Reactions</h1>. [Doctoral Dissertation]. University of Notre Dame; 2015. Available from: https://curate.nd.edu/show/qn59q239x0d


Iowa State University

2. Snell, Ryan William. Carbon-carbon bond forming reactions for bio-oil upgrading: heterogeneous catalyst and model compound studies.

Degree: 2012, Iowa State University

Development of a renewable liquid transportation fuel is likely to be one of the most important challenges faced by scientists during the 21st century. As biomass provides a renewable source of carbon it is ideally situated to supply this alternative to the traditional petroleum derived feedstocks. While there have been a number of different techniques used to convert biomass to liquid fuels, fast pyrolysis is particularly promising as it can quite efficiently break down biomass directly into a liquid. This resulting liquid, called bio-oil, is a very complex mixture containing a large number of oxygen functionalized compounds. Unfortunately, this oil has a number of issues that must be resolved before it can be effectively utilized as a liquid transportation fuel including acidity, reactivity, and low energy density. With this in mind, heterogeneously catalyzed C-C bond forming reactions potentially valuable for the upgrading of bio-oil were investigated. The aldol condensation is a well known reaction in organic chemistry usually promoted through the use of strong acid or bases. However, uses of these types of catalysts will likely cause undesirable side reactions. Ideally cooperative catalysis allows for weaker acids and bases to work in tandem to promote the reaction. Use of aluminum phosphate catalysts allowed for the tuning of the acidity and basicity of the materials through a nitridation process and hence probing of this cooperative catalysis. Through performing aldol condensations using model bio-oil compounds acetaldehyde, acetone, and MEK, it was found that acid and base sites were both needed to efficiently promote the cross condensation of the aldehyde and ketone. After reaction testing, a mechanism was proposed demonstrating the benefits of using heterogeneous catalysts as it allows for the coexistence of both acid and base sites. Ketonization of carboxylic acids is also an ideal reaction for bio-oil upgrading as it removes acidity and oxygen as well as creates C-C bonds. However, this reaction is almost always performed in the vapor phase due to the high temperatures necessary to achieve significant conversions. In order to try to engineer a more active catalyst able to perform the reaction at lower temperatures, more must be understood about ketonization. Condensed phase ketonization was examined using ceria catalysts calcined at different temperatures. It was found that the reaction proceeded either through the formation of carboxylates in the bulk or on the surface of the catalyst depending on the temperature of calcination. Moreover, through in-situ XRD, this trend was found to be true in the vapor phase as well. Kinetic studies found that the mechanism for both these routes was likely the same. As ketonization had been claimed to be sensitive to the surface structure of the ceria catalyst, shape selective ceria nanocrystals were synthesized and examined in acetic acid ketonization both in the vapor and condensed phases. It was found that in the condensed phase the catalysts underwent carboxylate…

Subjects/Keywords: Aldol condensation; Bio-oil; Cerium oxide; Ketonization; Chemical Engineering

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Snell, R. W. (2012). Carbon-carbon bond forming reactions for bio-oil upgrading: heterogeneous catalyst and model compound studies. (Thesis). Iowa State University. Retrieved from https://lib.dr.iastate.edu/etd/12467

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Snell, Ryan William. “Carbon-carbon bond forming reactions for bio-oil upgrading: heterogeneous catalyst and model compound studies.” 2012. Thesis, Iowa State University. Accessed December 16, 2018. https://lib.dr.iastate.edu/etd/12467.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Snell, Ryan William. “Carbon-carbon bond forming reactions for bio-oil upgrading: heterogeneous catalyst and model compound studies.” 2012. Web. 16 Dec 2018.

Vancouver:

Snell RW. Carbon-carbon bond forming reactions for bio-oil upgrading: heterogeneous catalyst and model compound studies. [Internet] [Thesis]. Iowa State University; 2012. [cited 2018 Dec 16]. Available from: https://lib.dr.iastate.edu/etd/12467.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Snell RW. Carbon-carbon bond forming reactions for bio-oil upgrading: heterogeneous catalyst and model compound studies. [Thesis]. Iowa State University; 2012. Available from: https://lib.dr.iastate.edu/etd/12467

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

3. Lopez-Ruiz, Juan A. Decarbonylation of Carboxylic Acids over Supported Metal Catalysts.

Degree: PhD, 2014, University of Virginia

Removal of oxygen from biomass-derived feedstocks such as carbohydrates and vegetable oil is often needed to produce chemicals and fuels. In this study, oxygen was removed from the model compounds heptanoic acid and propanoic acid by either decarboxylation, which yields carbon dioxide (CO2) and an alkane, and/or decarbonylation, which forms carbon monoxide (CO), water (H2O), and a linear alkene. Although decarbonylation produces an α-olefin as a primary product, the double bond can be isomerized to form an internal olefin or be hydrogenated to form an alkane. Recent work on decarboxylation/decarbonylation of carboxylic acids over transition metal catalysts is often performed in the presence of dihydrogen to inhibit catalyst deactivation, however, paraffins are the major product in those systems.

The effects of metal type, support composition, metal loading, reaction phase, acid concentration, and conversion on activity, selectivity, and stability are presented. We studied the liquid- and gas-phase decarbonylation of carboxylic acids on Pt, Pd, and Rh nanoparticles supported on carbon and silica supports in a continuous-flow fixed-bed reactor at temperatures ranging from 533 to 573 K. The liquid-phase turnover frequency (TOF) of heptanoic acid conversion over Pt at 573 K was fairly constant, 0.0050 s-1, as the catalyst dispersion and metal loading was varied. The liquid-phase TOF of Pd at 573 K was 0.00070 s-1 and was independent of support composition, weight loading, and acid concentration. A shift in product selectivity from decarboxylation products, paraffin and CO2, to decarbonylation products, olefins and CO, as previously discussed in the literature was most likely a result of changes in conversion. However, the decarboxylation products observed in the current study were likely formed in secondary side reactions such as water-gas shift (WGS) and hydrogenation.

Low conversion and high acid concentration experiments in liquid-phase and gas-phase operation suggest that the main reaction path for heptanoic acid and propanoic acid conversion is the decarbonylation reaction. Some direct decarboxylation was observed when operating in the gas-phase at very low concentrations of acid. The reaction was zero order in acid during the liquid-phase operation and high partial pressures during gas-phase operation, but was observed to be negative order in acid at very low partial pressures.

Characterization of catalysts after reaction revealed metal sintering, loss of surface area and loss of exposed metal during the liquid-phase operation. X-ray diffraction and electron microscopy revealed Pd sintering on a carbon support when operating in the liquid-phase at high acid concentration, but negligible Pd sintering when acid concentration was below 0.10 M. Palladium nanoparticles were more stable on the silica support during the liquid-phase operation. Furthermore, Pd sintering was negligible during the gas-phase experiments regardless of the support composition and acid concentration. Nevertheless, N2 physisorption…

Advisors/Committee Members: Davis, Robert J. (advisor).

Subjects/Keywords: Decarbonylation; Decarboxylation; Deoxygenation; Carboxylic Acid; Heptanoic Acid; Propanoic acid; Pt/C; Pd/C; Pt/SiO2; Rh/SiO2; Pd/SiO2; α-Olefin; Olefin; Paraffin; Ketonization; 1-Hexene; Hexane; 7-Tridecanone; Ethylene; Ethane; 3-Pentanone

…2 Scheme 1.3. Ketonization of heptanoic acid scheme 3 Scheme 2.1. Decarbonylation and… …Ketonization of heptanoic acid… …54 Scheme 3.2. Ketonization of heptanoic acid… …87 Scheme 4.2. Ketonization of propanoic acid… …ketonization, decarbonylation and decarboxylation [2]. This set of reactions is… 

Page 1 Page 2 Page 3 Page 4 Page 5 Page 6 Page 7

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Lopez-Ruiz, J. A. (2014). Decarbonylation of Carboxylic Acids over Supported Metal Catalysts. (Doctoral Dissertation). University of Virginia. Retrieved from http://libra.virginia.edu/catalog/libra-oa:7979

Chicago Manual of Style (16th Edition):

Lopez-Ruiz, Juan A. “Decarbonylation of Carboxylic Acids over Supported Metal Catalysts.” 2014. Doctoral Dissertation, University of Virginia. Accessed December 16, 2018. http://libra.virginia.edu/catalog/libra-oa:7979.

MLA Handbook (7th Edition):

Lopez-Ruiz, Juan A. “Decarbonylation of Carboxylic Acids over Supported Metal Catalysts.” 2014. Web. 16 Dec 2018.

Vancouver:

Lopez-Ruiz JA. Decarbonylation of Carboxylic Acids over Supported Metal Catalysts. [Internet] [Doctoral dissertation]. University of Virginia; 2014. [cited 2018 Dec 16]. Available from: http://libra.virginia.edu/catalog/libra-oa:7979.

Council of Science Editors:

Lopez-Ruiz JA. Decarbonylation of Carboxylic Acids over Supported Metal Catalysts. [Doctoral Dissertation]. University of Virginia; 2014. Available from: http://libra.virginia.edu/catalog/libra-oa:7979

.