We have used quasi-elastic neutron scattering to determine the concentration-dependent corrected and transport diffusivities for CF4 adsorbed in silicalite at 200 and 250 K. Equilibrium molecular dynamics simulations have also been used to compute the diffusivities under the same condition. We find quantitative agreement between our simulation and experimental results, which show that the corrected diffusivity of CF4 decreases as the molecular loading inside the zeolite is increased. Earlier simulations and experiments have examined self-diffusion of CF4 in silicalite, so for the first time data are now available to directly compare experimental and MD results for self-diffusion and collective diffusion simultaneously. The agreement between the simulation and experimental results provide strong support for the use of atomistic simulations to quantitatively explore the diffusion of small molecules in nanoporous materials.