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Catalytic conversion of CO2 and lignin into valuable chemicals

Jensen, Lucy LU (2024)
Abstract
Increasing concern regarding climate change and environmental sustainability have driven research regarding the development of innovative solutions for CO₂ mitigation and biomass utilization. This thesis explores the catalytic conversion of CO₂ and lignin into valuable chemicals, as a promising approach to achieving carbon neutrality and enhancing the circular economy. The study focused on two key processes: the catalytic hydrogenation of CO₂ via the reverse water-gas shift (RWGS) reaction, and the oxidative depolymerization of lignin for the production of aromatic compounds. The work started with CO2 hydrogenation, followed by oxidative depolymerization of lignin, then bioconversion of lignin-derived monomers to produce fine... (More)
Increasing concern regarding climate change and environmental sustainability have driven research regarding the development of innovative solutions for CO₂ mitigation and biomass utilization. This thesis explores the catalytic conversion of CO₂ and lignin into valuable chemicals, as a promising approach to achieving carbon neutrality and enhancing the circular economy. The study focused on two key processes: the catalytic hydrogenation of CO₂ via the reverse water-gas shift (RWGS) reaction, and the oxidative depolymerization of lignin for the production of aromatic compounds. The work started with CO2 hydrogenation, followed by oxidative depolymerization of lignin, then bioconversion of lignin-derived monomers to produce fine chemicals.

For the CO₂ conversion, an NiPdIr/CeZrO2 catalyst was used in the RWGS reaction to selectively convert CO₂ into CO, which is a key building block for various chemical processes such as syngas. In the study, the catalyst's performance was evaluated in terms of activity and selectivity under different reaction conditions. Multiple techniques were used to charactize the catalyst to study the effect of promoters on CO yield.

Lignin, a complex biopolymer that is difficult to work, was subjected to oxidative depolymerization to produce high-value aromatic chemicals. Central composite design (CCD) and Box-Behnken design (BBD) quadratic regression models were used to investigate optimization of the process conditions, including the lignin concentration, temperature, catalyst composition, oxygen pressure, and base concentration; these were systematically varied to maximize the yield of target aromatics such as vanillin and syringaldehyde.

The results demonstrate that the NiPdIr/CeZrO2 catalyst exhibited high CO selectivity and stability during the RWGS reaction, providing an efficient pathway for CO₂ conversion. For lignin conversion, the optimized oxidative depolymerization process achieved good yields of aromatic compounds, highlighting the potential of lignin as a renewable feedstock for chemical production.

Finally, bioconversion of vanillin was studied using an engineered strain of Pseudomonas putida CJ475. This strain has been modified for vanillin consumption and muconic-acid production, with the protocatechuate and catechol branches of the beta-ketoadipate pathway connected through the expression of a decarboxylase (aroY) and two helper proteins (ecdB and ecdD). Vanillin was converted into muconic acid, which is a promising precursor to industrial products such as adipic acid for nylon, terephthalic acid for PET plastics, and biodegradable polymers for sustainable packaging solutions.
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author
supervisor
opponent
  • Assoc. Prof. Kusar, Henrik, KTH Royal Institute of Technology, Sweden.
organization
publishing date
type
Thesis
publication status
published
subject
keywords
CO2 conversion, lignin, RWGS, biocoversion, catalyst, oxidative depolyemrization.
pages
100 pages
publisher
Chemical Engineering, Lund University
defense location
Lecture Hall KC:C, Kemicentrum, Naturvetarvägen 14, Faculty of Engineering LTH, Lund University, Lund.
defense date
2024-11-15 13:00:00
ISBN
978-91-8096-072-4
978-91-8096-073-1
language
English
LU publication?
yes
id
025ecc03-5ec6-4c1a-939a-a8a7e6cd245c
date added to LUP
2024-10-23 11:52:02
date last changed
2025-04-04 15:13:18
@phdthesis{025ecc03-5ec6-4c1a-939a-a8a7e6cd245c,
  abstract     = {{Increasing concern regarding climate change and environmental sustainability have driven research regarding the development of innovative solutions for CO₂ mitigation and biomass utilization. This thesis explores the catalytic conversion of CO₂ and lignin into valuable chemicals, as a promising approach to achieving carbon neutrality and enhancing the circular economy. The study focused on two key processes: the catalytic hydrogenation of CO₂ via the reverse water-gas shift (RWGS) reaction, and the oxidative depolymerization of lignin for the production of aromatic compounds. The work started with CO2 hydrogenation, followed by oxidative depolymerization of lignin, then bioconversion of lignin-derived monomers to produce fine chemicals.<br/><br/>For the CO₂ conversion, an NiPdIr/CeZrO2 catalyst was used in the RWGS reaction to selectively convert CO₂ into CO, which is a key building block for various chemical processes such as syngas. In the study, the catalyst's performance was evaluated in terms of activity and selectivity under different reaction conditions. Multiple techniques were used to charactize the catalyst to study the effect of promoters on CO yield. <br/><br/>Lignin, a complex biopolymer that is difficult to work, was subjected to oxidative depolymerization to produce high-value aromatic chemicals. Central composite design (CCD) and Box-Behnken design (BBD) quadratic regression models were used to investigate optimization of the process conditions, including the lignin concentration, temperature, catalyst composition, oxygen pressure, and base concentration; these were systematically varied to maximize the yield of target aromatics such as vanillin and syringaldehyde.<br/><br/>The results demonstrate that the NiPdIr/CeZrO2 catalyst exhibited high CO selectivity and stability during the RWGS reaction, providing an efficient pathway for CO₂ conversion. For lignin conversion, the optimized oxidative depolymerization process achieved good yields of aromatic compounds, highlighting the potential of lignin as a renewable feedstock for chemical production. <br/><br/>Finally, bioconversion of vanillin was studied using an engineered strain of Pseudomonas putida CJ475. This strain has been modified for vanillin consumption and muconic-acid production, with the protocatechuate and catechol branches of the beta-ketoadipate pathway connected through the expression of a decarboxylase (aroY) and two helper proteins (ecdB and ecdD). Vanillin was converted into muconic acid, which is a promising precursor to industrial products such as adipic acid for nylon, terephthalic acid for PET plastics, and biodegradable polymers for sustainable packaging solutions.<br/>}},
  author       = {{Jensen, Lucy}},
  isbn         = {{978-91-8096-072-4}},
  keywords     = {{CO2 conversion, lignin, RWGS, biocoversion, catalyst, oxidative depolyemrization.}},
  language     = {{eng}},
  month        = {{11}},
  publisher    = {{Chemical Engineering, Lund University}},
  school       = {{Lund University}},
  title        = {{Catalytic conversion of CO2 and lignin into valuable chemicals}},
  year         = {{2024}},
}