Synthesis of sulfonated carbon metal catalysts and optimization of levulinic acid production from oil palm empty fruit bunch cellulose

Levulinic acid (LA) is an important building block chemical that can be produced from both monosaccharides and polysaccharides via hydrolysis reactions. Nowadays, biomass waste including oil palm empty fruit bunches (OPEFB) is an attractive source of LA due to their high cellulose content. Therefore, this study focuses on the production of LA from OPEFB-based cellulose utilizing sulfonated carbon metal catalysts. In the first part, a sulfonated carbon metal catalyst was synthesized and evaluated for its performance to produce LA. Among different ratios of iron (Fe) and nickel (Ni)-based catalysts, Fe.75Ni which referred to 25% Fe and 75% Ni, exhibited the most promising activity for LA production and yielded 10.51 % from cellulose at 180 ºC for 5 h using 0.15 g catalyst loading. Subsequent impregnation of different Fe.75Ni metal loadings into sulfonated carbon catalyst led to further improvement in LA synthesis. 15%FeNi/ACSO3H (15% Fe.75Ni impregnated into ACSO3H) catalyst achieved the highest LA which was 16.76%. based on theoretical yield from cellulose at 180 °C, 5 hours, and 0.15g catalyst loading. The synthesized catalyst can be reused for four reaction cycles. In the second part, the catalyst characterization was performed using X-ray diffraction (XRD), temperature-programmed desorption of ammonia (TPD-NH3), thermogravimetric analysis (TGA), N2 adsorption-desorption, X-ray fluorescence (XRF), field emission scanning electron microscope (FESEM), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Characterization studies confirmed successful metal incorporation in the ACSO3H catalyst. Furthermore, the 15%FeNi/ACSO3H catalyst demonstrated favorable properties such as a good surface area, high acidity value and good thermal stability which are advantageous to the synthesis of LA. However, from the results obtained using cellulose, the LA yield was relatively low indicating the necessity for cellulose modification. Subsequently, the study focused on enhancing the LA yield from cellulose. Since the main goal of the study is to explore the use of cellulose from OPEFB, the initial step focused on cellulose isolation from OPEFB. Successful isolation of cellulose was achieved using the dewaxing technique, followed by the treatment with sodium hydroxide and sodium chlorite solution, yielding 8.98% LA based on theoretical yield at 160 °C, 2 hours and 0.10 g catalyst loading. Molten salt hydrates (MSHs) pretreatment, particularly with lithium bromide (LiBr), significantly improved cellulose accessibility and hydrolysis efficiency and resulted in the highest LA yield of 24.3% compared to other MSHs. The optimization study focused on identifying the optimal conditions for LA synthesis from LiBr-pretreated OPEFB-based cellulose using Response Surface Methodology (RSM) revealed that the highest LA production (78.12%) was achieved at 200 °C, 4.5 hours and 10% catalyst loading. The kinetics model accurately predicted first-order irreversible reaction kinetics by combining experimental work and mathematical modeling. Its accuracy was confirmed by its correlation with experimental product distribution profiles, revealing important reaction parameters, such as the activation energy for the conversion into LA, which was 59.01 - 102.45 kJ/mol. In conclusion, the applied approach presents a novel technique for converting abundant and cost-effective cellulosic biomass into LA.

Text FK 2024 39 - Declaration Form.pdf Restricted to Repository staff only Available under License Creative Commons Attribution Non-commercial No Derivatives. Download (734kB) Text FK 2024 39 - Full Text.pdf Available under License Creative Commons Attribution Non-commercial No Derivatives. Download (7MB) Text FK 2024 39.pdf Restricted to Repository staff only Available under License Creative Commons Attribution Non-commercial No Derivatives. Download (7MB) Official URL or Download Paper: http://ethesis.upm.edu.my/id/eprint/19004

Actions (login required)

View Item