Sammanfattning
Non-renewable feedstock should be replaced with renewable resources in the production of energy, chemical commodities, and materials to increase sustainability. Biomass, especially 2nd generation biomass sources such as forest residues and agricultural waste are good renewable candidates for the production of biofuels, materials, and chemicals. Different compounds can be obtained from biomass, among which, some have been classified as platform molecules due to the versatile possibilities in their further transformation to values added products. Among these platform molecules, γ-valerolactone (GVL) is a valuable molecule that may be used as a precursor for high-value materials, as a combustible additive, and as a non-toxic non-polar solvent with good physical and chemical properties. This thesis is
focused on studying the production of γ-valerolactone from alkyl levulinates from a kinetic and thermodynamic perspective.
The production proceeds via a two-step reaction pathway, which comprises catalytic hydrogenation of alkyl levulinates followed by an internal cyclization to form GVL. A Ru/C solid catalyst was used to enhance the hydrogenation of levulinates with molecular hydrogen.
In the first part of the work, the influence of experimental parameters such as hydrogen pressure, temperature, and initial reactant concentration on the reaction rates and selectivity were investigated using butyl levulinate as a reference reactant. A mathematical model was proposed for the reaction kinetics using Bayesian inference. An autoclave was used to investigate experimentally the reaction kinetics in isothermal and isobaric conditions. The reactant and product concentrations were analyzed by GC-FID. It was observed that the cyclization was the rate limiting step in the GVL production.
In the second part, the hydrogenation of levulinic acid (LA) and butyl levulinate to GVL was investigated. The motivation comes from the fact that the solvolysis of glucose or fructose to butyl levulinate also leads to the production of LA as a side product. A sulfonic resin, Amberlite
IR120, was used to accelerate the internal cyclization reaction. A kinetic model considering the dual catalyst system, Ru/C and Amberlite IR120, was obtained via Bayesian inference. A cross-validation method, K-fold method, was used to evaluate the predictive ability of the models.
Risks related to the production of GVL can be understood and evaluated with the help of thermodynamics. Reaction enthalpy is a key thermodynamic factor in thermal risk assessment, as it contributes to the severity of risks involved. The values of the reaction enthalpies for both reaction steps considering five n-alkyl levulinates (from methyl to pentyl levulinates) were determined. Batch calorimeters operated under isothermal and isobaric conditions were utilized in the experiments. A Mettler Toledo RC1mx calorimeter was used for the hydrogenation reaction, while a Tian Calvet C80 microcalorimeter was used for the cyclization reaction. The influence of parameters such as temperature, alkyl substituent, solvent effect, and initial concentration on the reaction rates and selectivity was studied for the hydrogenation reaction.
The current work contributes to the production of biomass derived γ-valerolactone, a green platform molecule.
focused on studying the production of γ-valerolactone from alkyl levulinates from a kinetic and thermodynamic perspective.
The production proceeds via a two-step reaction pathway, which comprises catalytic hydrogenation of alkyl levulinates followed by an internal cyclization to form GVL. A Ru/C solid catalyst was used to enhance the hydrogenation of levulinates with molecular hydrogen.
In the first part of the work, the influence of experimental parameters such as hydrogen pressure, temperature, and initial reactant concentration on the reaction rates and selectivity were investigated using butyl levulinate as a reference reactant. A mathematical model was proposed for the reaction kinetics using Bayesian inference. An autoclave was used to investigate experimentally the reaction kinetics in isothermal and isobaric conditions. The reactant and product concentrations were analyzed by GC-FID. It was observed that the cyclization was the rate limiting step in the GVL production.
In the second part, the hydrogenation of levulinic acid (LA) and butyl levulinate to GVL was investigated. The motivation comes from the fact that the solvolysis of glucose or fructose to butyl levulinate also leads to the production of LA as a side product. A sulfonic resin, Amberlite
IR120, was used to accelerate the internal cyclization reaction. A kinetic model considering the dual catalyst system, Ru/C and Amberlite IR120, was obtained via Bayesian inference. A cross-validation method, K-fold method, was used to evaluate the predictive ability of the models.
Risks related to the production of GVL can be understood and evaluated with the help of thermodynamics. Reaction enthalpy is a key thermodynamic factor in thermal risk assessment, as it contributes to the severity of risks involved. The values of the reaction enthalpies for both reaction steps considering five n-alkyl levulinates (from methyl to pentyl levulinates) were determined. Batch calorimeters operated under isothermal and isobaric conditions were utilized in the experiments. A Mettler Toledo RC1mx calorimeter was used for the hydrogenation reaction, while a Tian Calvet C80 microcalorimeter was used for the cyclization reaction. The influence of parameters such as temperature, alkyl substituent, solvent effect, and initial concentration on the reaction rates and selectivity was studied for the hydrogenation reaction.
The current work contributes to the production of biomass derived γ-valerolactone, a green platform molecule.
| Originalspråk | Engelska |
|---|---|
| Handledare |
|
| Utgivningsort | Rouen - Turku |
| Förlag | |
| Tryckta ISBN | 978-952-12-4303-5 |
| Elektroniska ISBN | 978-952-12-4304-2 |
| Status | Publicerad - 2023 |
| MoE-publikationstyp | G5 Doktorsavhandling (artikel) |