Kinnaer, Marty
[UCL]
Debecker, Damien P.
[UCL]
With today’s increasing environmental concerns, the development of sustainable materials and energy are of utmost importance. Working on the replacement of petroleum-based chemicals by biomass-derived chemicals can help reduce the consumption of fossil energy sources and lower our dependence to petroleum. This master thesis aims to help develop a new sustainable, safe and efficient process for the production of γ-valerolactone from biomass-derived levulinic acid by creating an efficient catalyst for this reaction. Levulinic acid is a biomass-derived platform molecule that can be obtained from most plant-based resources, including lignocellulosic material. Lignocellulosic biomass is known for its hardiness as plants have evolved this tissue to resist microbial and enzymatic degradation. Finding ways to exploit this biomass fraction is important, as it is most often discarded, wasted. Gamma-valerolactone (GVL), can be used as the base chemical for a wide variety of applications, many of them being currently fulfilled by petroleum-based chemicals. It can be used as a solvent or fuel additive and even be transformed further to create synthetic fuels or polymers. In this work, we have focused on making postsynthetic Zr-β zeolites, by removing the aluminum of commercial zeolite Beta and subsequently incorporating zirconium in the defect sites formed by the removal of Al. This allows to make Zr-β zeolites with controlled morphology, contrarily to its direct synthesis. Direct, hydrothermal synthesis of Zr-β yields large crystals in the micrometer range, as it is 20 days long, and requires the use of hydrofluoric acid which is harmful for the both the environment and for the operators. Zr-β zeolites are microporous materials; only its external surface area is catalytically active, hence the need to improve their surface-to-volume ratio. We have proven that postsynthetic Zr-β zeolites can be used for the conversion of levulinic acid to γ-valerolactone under atmospheric pressure at 118°C by catalytic hydrogen transfer with 2-pentanol. The catalyzed reaction is the Meerwein-Ponndorf-Verley reduction of the ketone function of the substrate. When used with the ethyl ester of levulinic acid, ethyl levulinate, our catalysts have reached selectivities up to 96% for γ-valerolactone. We made highly active Zr-β zeolites with Si/Zr molar ratios down to 41 whereas hydrothermal synthesis does not work below a ratio of 75. We have also been able to prove that the zirconium was incorporated in the zeolitic framework, and not supported on its surface in the form of ZrO2. With the knowledge gained from this master thesis, we will be working in the future on the creation of hierarchal Zr-β zeolites from nanozeolites pre-made in our lab.
Bibliographic reference |
Kinnaer, Marty. Postsynthetic Zr-Beta zeolites for the conversion of levulinic feedstock to gamma-valerolactone. Faculté des bioingénieurs, Université catholique de Louvain, 2020. Prom. : Debecker, Damien P.. |
Permanent URL |
http://hdl.handle.net/2078.1/thesis:23013 |