| Summary: |
The main purpose of this work is the study of enzymatic transesterification reactions in supercritical solvents to produce high added value products for the fragrances industries. One product of great relevance is decyl acetate. Besides being listed on the Food and Drug Administration as a suitable flavouring agent, decyl acetate finds wide application in the fragrance industry where its floral odour is of great usefulness. Since it mainly appears in nature in expensive oils, enzyme catalysis in a green solvent can be a valuable process for production of natural decyl acetate.
For this reaction, several immobilized enzymes commercially available will be used. This project includes both experimental and modelling work for the different tasks:
- Kinetic studies in organic and supercritical media, in a batch reactor;
- Phase equilibria studies in supercritical media;
- Enzymatic synthesis studies in supercritical media in a continuous reactor;
- Batch and continuous reactor modelling.
Preliminary studies will be performed at low pressure in organic solvents. The influence of several parameters such as temperature, solvent, biocatalyst, water activity and pH on the reaction rate will be evaluated. Afterwards, these studies will also be carried out in supercritical media. For that, an experimental apparatus that includes a batch reactor will be used to obtain the kinetic data in the supercritical solvent. In this way, a comparison between organic and supercritical media enzymatic catalysis can be performed.
In order to establish the reactor operation conditions in one homogeneous phase, in the supercritical solvent, phase equilibria for the enzymatic reaction substrates and products will be measured. For that, the reactor will be used as an equilibrium cell and a sampling section is added to measure the composition of both the vapour and liquid phases. This experimental data will also be useful for the simulation and design of the subsequent separation stage  |
Summary
The main purpose of this work is the study of enzymatic transesterification reactions in supercritical solvents to produce high added value products for the fragrances industries. One product of great relevance is decyl acetate. Besides being listed on the Food and Drug Administration as a suitable flavouring agent, decyl acetate finds wide application in the fragrance industry where its floral odour is of great usefulness. Since it mainly appears in nature in expensive oils, enzyme catalysis in a green solvent can be a valuable process for production of natural decyl acetate.
For this reaction, several immobilized enzymes commercially available will be used. This project includes both experimental and modelling work for the different tasks:
- Kinetic studies in organic and supercritical media, in a batch reactor;
- Phase equilibria studies in supercritical media;
- Enzymatic synthesis studies in supercritical media in a continuous reactor;
- Batch and continuous reactor modelling.
Preliminary studies will be performed at low pressure in organic solvents. The influence of several parameters such as temperature, solvent, biocatalyst, water activity and pH on the reaction rate will be evaluated. Afterwards, these studies will also be carried out in supercritical media. For that, an experimental apparatus that includes a batch reactor will be used to obtain the kinetic data in the supercritical solvent. In this way, a comparison between organic and supercritical media enzymatic catalysis can be performed.
In order to establish the reactor operation conditions in one homogeneous phase, in the supercritical solvent, phase equilibria for the enzymatic reaction substrates and products will be measured. For that, the reactor will be used as an equilibrium cell and a sampling section is added to measure the composition of both the vapour and liquid phases. This experimental data will also be useful for the simulation and design of the subsequent separation stage to obtain the valuable product from the final reaction mixture. A group-contribution equation of state developed by the group will be applied to model the phase equilibria experimental data.
In the final step, the production in a continuous mode will be studied. For that, an experimental apparatus that includes a continuous reactor operating at high pressure will be set up. Several parameters will be considered, e.g., flow-rate, feeding stream, water content, temperature and pressure.
New mathematical models will be proposed to describe the production of decyl acetate in the batch and continuous reactors, by taking into account the enzymatic reaction with two-substrates and the mass transfer limitations.
The different tasks proposed in this project have as a final and broad main purpose to study the enzymatic production of decyl acetate in supercritical media, in a continuous mode. The methodologies and the technology to be developed in this project can also be extended to other valuable esters. |