Biomass Conversion over Heteropoly Acid Catalysts

dc.contributor.advisorHan, Yu
dc.contributor.authorZhang, Jizhe
dc.contributor.committeememberHuang, Kuo-Wei
dc.contributor.committeememberLai, Zhiping
dc.contributor.committeememberTakanabe, Kazuhiro
dc.contributor.departmentPhysical Science and Engineering (PSE) Division
dc.date.accessioned2015-05-13T11:57:30Z
dc.date.available2015-05-13T11:57:30Z
dc.date.issued2015-04
dc.description.abstractBiomass is a natural resource that is both abundant and sustainable. Its efficient utilization has long been the focus of research and development efforts with the aim to substitute it for fossil-based feedstock. In addition to the production of biofuels (e.g., ethanol) from biomass, which has been to some degree successful, its conversion to high value-added chemicals is equally important. Among various biomass conversion pathways, catalytic conversion is usually preferred, as it provides a cost-effective and eco-benign route to the desired products with high selectivities. The research of this thesis is focused on the conversion of biomass to various chemicals of commercial interest by selective catalytic oxidation. Molecular oxygen is chosen as the oxidant considering its low cost and environment friendly features in comparison with commonly used hydrogen peroxide. However, the activation of molecular oxygen usually requires high reaction temperatures, leading to over oxidation and thus lower selectivities. Therefore, it is highly desirable to develop effective catalysts for such conversion systems. We use kegging-type heteropoly acids (HPAs) as a platform for catalysts design because of their high catalytic activities and ease of medication. Using HPA catalysts allows the conversion taking place at relatively low temperature, which is beneficial to saving production cost as well as to improving the reaction selectivity. The strong acidity of HPA promotes the hydrolysis of biomass of giant molecules (e.g. cellulose), which is the first as well as the most difficult step in the conversion process. Under certain circumstances, a HPA combines the merits of homogeneous and heterogeneous catalysts, acting as an efficient homogeneous catalyst during the reaction while being easily separated as a heterogeneous catalyst after the reaction. We have successfully applied HPAs in several biomass conversion systems. Specially, we prepared a HPA-based bi-functional catalyst (Au/Cs2HPW12O40) that enabled the selective conversion of cellobiose to gluconic acid with a very high yield of 96.4% (Chapter II); we realized a direct oxidative conversion of cellulose to glycolic acid (yield of 49.3 %) in a water medium for the first time, by using a phosphomolybdic acid catalyst (chapter III); we found that a vanadium-substituted phosphomolybdic acid catalyst (H4PVMo11O40) is capable of converting various biomass-derived substrates to formic acid and acetic acid with high selectivity, and under optimized reaction conditions, high yield of formic acid (67.8%) can be obtained from cellulose (chapter IV); we discovered that the vanadium-substituted phosphomolybdic acids can also selectively oxidize glycerol, a low-cost by-product of biodiesel, to formic acid, and interestingly this conversion can be performed in highly concentration aqueous solution (glycerol: water = 50: 50), giving rise to exceptionally high conversion efficiency (chapter V). These results reveal that HPAs are useful and suitable catalysts for selective oxidation of biomass, and that the reaction pathway is largely determined by the type of addenda atom in the HPA catalyst. The optimization of the reaction conditions and processes in these systems are also discussed in this thesis.
dc.identifier.citationZhang, J. (2015). Biomass Conversion over Heteropoly Acid Catalysts. KAUST Research Repository. https://doi.org/10.25781/KAUST-1994J
dc.identifier.doi10.25781/KAUST-1994J
dc.identifier.urihttp://hdl.handle.net/10754/552692
dc.language.isoen
dc.person.id113364
dc.subjectbiomass conversion
dc.subjectheteropoly acid
dc.subjectoxidation
dc.titleBiomass Conversion over Heteropoly Acid Catalysts
dc.typeDissertation
display.details.left<span><h5>Type</h5>Dissertation<br><br><h5>Authors</h5><a href="https://repository.kaust.edu.sa/search?query=orcid.id:0000-0001-5567-8204&spc.sf=dc.date.issued&spc.sd=DESC">Zhang, Jizhe</a> <a href="https://orcid.org/0000-0001-5567-8204" target="_blank"><img src="https://repository.kaust.edu.sa/server/api/core/bitstreams/82a625b4-ed4b-40c8-865a-d6a5225a26a4/content" width="16" height="16"/></a><br><br><h5>Advisors</h5><a href="https://repository.kaust.edu.sa/search?query=orcid.id:0000-0003-1462-1118&spc.sf=dc.date.issued&spc.sd=DESC">Han, Yu</a> <a href="https://orcid.org/0000-0003-1462-1118" target="_blank"><img src="https://repository.kaust.edu.sa/server/api/core/bitstreams/82a625b4-ed4b-40c8-865a-d6a5225a26a4/content" width="16" height="16"/></a><br><br><h5>Committee Members</h5><a href="https://repository.kaust.edu.sa/search?query=orcid.id:0000-0003-1900-2658&spc.sf=dc.date.issued&spc.sd=DESC">Huang, Kuo-Wei</a> <a href="https://orcid.org/0000-0003-1900-2658" target="_blank"><img src="https://repository.kaust.edu.sa/server/api/core/bitstreams/82a625b4-ed4b-40c8-865a-d6a5225a26a4/content" width="16" height="16"/></a><br><a href="https://repository.kaust.edu.sa/search?query=orcid.id:0000-0001-9555-6009&spc.sf=dc.date.issued&spc.sd=DESC">Lai, Zhiping</a> <a href="https://orcid.org/0000-0001-9555-6009" target="_blank"><img src="https://repository.kaust.edu.sa/server/api/core/bitstreams/82a625b4-ed4b-40c8-865a-d6a5225a26a4/content" width="16" height="16"/></a><br><a href="https://repository.kaust.edu.sa/search?query=orcid.id:0000-0001-5374-9451&spc.sf=dc.date.issued&spc.sd=DESC">Takanabe, Kazuhiro</a> <a href="https://orcid.org/0000-0001-5374-9451" target="_blank"><img src="https://repository.kaust.edu.sa/server/api/core/bitstreams/82a625b4-ed4b-40c8-865a-d6a5225a26a4/content" width="16" height="16"/></a><br><br><h5>Program</h5><a href="https://repository.kaust.edu.sa/search?spc.sf=dc.date.issued&spc.sd=DESC&f.program=Chemical Science,equals">Chemical Science</a><br><br><h5>KAUST Department</h5><a href="https://repository.kaust.edu.sa/search?spc.sf=dc.date.issued&spc.sd=DESC&f.department=Physical Science and Engineering (PSE) Division,equals">Physical Science and Engineering (PSE) Division</a><br><br><h5>Date</h5>2015-04</span>
display.details.right<span><h5>Abstract</h5>Biomass is a natural resource that is both abundant and sustainable. Its efficient utilization has long been the focus of research and development efforts with the aim to substitute it for fossil-based feedstock. In addition to the production of biofuels (e.g., ethanol) from biomass, which has been to some degree successful, its conversion to high value-added chemicals is equally important. Among various biomass conversion pathways, catalytic conversion is usually preferred, as it provides a cost-effective and eco-benign route to the desired products with high selectivities. The research of this thesis is focused on the conversion of biomass to various chemicals of commercial interest by selective catalytic oxidation. Molecular oxygen is chosen as the oxidant considering its low cost and environment friendly features in comparison with commonly used hydrogen peroxide. However, the activation of molecular oxygen usually requires high reaction temperatures, leading to over oxidation and thus lower selectivities. Therefore, it is highly desirable to develop effective catalysts for such conversion systems. We use kegging-type heteropoly acids (HPAs) as a platform for catalysts design because of their high catalytic activities and ease of medication. Using HPA catalysts allows the conversion taking place at relatively low temperature, which is beneficial to saving production cost as well as to improving the reaction selectivity. The strong acidity of HPA promotes the hydrolysis of biomass of giant molecules (e.g. cellulose), which is the first as well as the most difficult step in the conversion process. Under certain circumstances, a HPA combines the merits of homogeneous and heterogeneous catalysts, acting as an efficient homogeneous catalyst during the reaction while being easily separated as a heterogeneous catalyst after the reaction. We have successfully applied HPAs in several biomass conversion systems. Specially, we prepared a HPA-based bi-functional catalyst (Au/Cs2HPW12O40) that enabled the selective conversion of cellobiose to gluconic acid with a very high yield of 96.4% (Chapter II); we realized a direct oxidative conversion of cellulose to glycolic acid (yield of 49.3 %) in a water medium for the first time, by using a phosphomolybdic acid catalyst (chapter III); we found that a vanadium-substituted phosphomolybdic acid catalyst (H4PVMo11O40) is capable of converting various biomass-derived substrates to formic acid and acetic acid with high selectivity, and under optimized reaction conditions, high yield of formic acid (67.8%) can be obtained from cellulose (chapter IV); we discovered that the vanadium-substituted phosphomolybdic acids can also selectively oxidize glycerol, a low-cost by-product of biodiesel, to formic acid, and interestingly this conversion can be performed in highly concentration aqueous solution (glycerol: water = 50: 50), giving rise to exceptionally high conversion efficiency (chapter V). These results reveal that HPAs are useful and suitable catalysts for selective oxidation of biomass, and that the reaction pathway is largely determined by the type of addenda atom in the HPA catalyst. The optimization of the reaction conditions and processes in these systems are also discussed in this thesis.<br><br><h5>Citation</h5>Zhang, J. (2015). Biomass Conversion over Heteropoly Acid Catalysts. KAUST Research Repository. https://doi.org/10.25781/KAUST-1994J<br><br><h5>DOI</h5><a href="https://doi.org/10.25781/KAUST-1994J">10.25781/KAUST-1994J</a></span>
orcid.id0000-0001-5374-9451
orcid.id0000-0001-9555-6009
orcid.id0000-0003-1900-2658
orcid.id0000-0003-1462-1118
orcid.id0000-0001-5567-8204
refterms.dateFOA2018-06-14T07:43:35Z
thesis.degree.disciplineChemical Science
thesis.degree.grantorKing Abdullah University of Science and Technology
thesis.degree.nameDoctor of Philosophy
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