"How does mass transfer influence chemical reactor design and performance? Discuss the fundamental principles of mass transfer in reactors, including diffusion and convection. Explain how factors such as reactor geometry, operating conditions, and fluid properties affect mass transfer rates. Consider the role of mass transfer limitations in controlling reaction kinetics and selectivity. Provide examples illustrating the significance of mass transfer phenomena in various chemical engineering processes, such as catalysis, polymerization, and distillation. Offer insights into optimizing reactor design for enhanced mass transfer efficiency."