Thermodynamics and transport phenomena are essential for understanding and optimizing chemical processes, especially in catalytic reactions and reactor design. Thermodynamics helps predict reaction direction, establish equilibrium, and calculate state variables like enthalpy and Gibbs free energy. It also determines maximum conversion and optimal operating conditions in catalytic systems. Transport phenomena address the movement of fluids, energy, and species, influencing reactant interaction with catalyst surfaces and energy distribution in reactors. In fixed-bed reactors, mass and heat transfer rates affect reaction rates and catalyst stability. Combining thermodynamics and transport phenomena is crucial for scaling up laboratory processes to industrial applications, ensuring efficiency, cost-effectiveness, and sustainability in industries like petrochemicals, pharmaceuticals, and renewable energy.