Despite the increasing interest in the global transition to renewable energy sources, as of today, there is no such energy source known that could fully replace the energy production from fossil fuels. The latter could be substituted by renewable energy sources, which significantly reduce the negative environmental impact. Renewable energy sources integrated into the energy grid bring about fluctuations, which can be addressed by storing energy during production peaks and releasing it back into the system during production shortages. Liquid Organic Hydrogen Carrier (LOHC) systems represent a form of hydrogen-based energy storage that enables safe storage and transport.
2-methylquinoline is an example of a nitrogen heterocyclic molecule that could potentially be used as a component of LOHC systems. In my master's thesis, I investigated the kinetics of the hydrogenation of 2-methylquinoline on a 5 wt. % Ru/Al2O3 catalyst. I examined the influence of reaction conditions such as temperature, pressure, catalyst mass, and initial concentration of 2-methylquinoline. Through (micro)kinetic modeling of the system, I studied the mechanism and rate of the chemical reaction, and calculated the reaction kinetic parameters.
The results demonstrated that the reaction within the temperature range of 100 – 180 °C is not strongly temperature-dependent. Pressure, and consequently hydrogen concentration within the range of 25 to 75 bar, greatly affects the reaction rate. Furthermore, increasing the catalyst mass from 0.05 g to 0.15 g and decreasing the initial concentration of 2-methylquinoline from 2.7 to 0.5 mol L–1 were found to accelerate the reaction rate. The model followed the trends of experimental data with calculated reaction rate constants for individual reaction steps on the catalyst surface: k1=1500 min–1, k2=578 min–1, k3=554 min–1, k4=60 min–1 and activation energies Ea1=23463 J mol–1, Ea2=16479 J mol–1, Ea3=8519 J mol–1 and Ea4=18079 J mol–1.
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