Aromatic hydrocarbons such as the isomers of trimethylbenzene (TMB) are extracted from crude oil along with other aromatic hydrocarbon groups. The isomers of trimethylbenzene are mostly abundant as a mixture in the crude oil stream. These isomers are used as precursors in industries such as pharmaceutical, agriculture, plastics, dyes, textiles, food and so on. However, these are needed in their purest form in all the applications mentioned above. Efficient separation of these isomers from their mixtures is very critical to their application in the industry, however, the conventional separation techniques such as chromatography, crystallization, fractional distillation etc. face challenges due to close proximity of these isomers with respect to their physical properties such as mass, density, melting point, boiling point etc. and cost intensive. Separation of these isomers using membrane-based techniques is not only efficient but also cost-effective. In these techniques, the membranes are usually made up of porous materials such as zeolites. Zeolites are the microporous crystalline silicate materials, consisting of void networks in the shape of cages/channels of various topologies. These networks allow only molecules of certain shape and size, blocking the rest, and thus acting as molecular sieves. Known for their stability even at higher temperatures, the zeolites are particularly used as molecular sieves at the industry scale for the hydrocarbon separation. The choice of the zeolite is dependent on the hydrocarbons that are to be separated, usually the effective pore diameter of the zeolite should be close to the size of the hydrocarbon molecule. The design of the separation method is entirely based on the structure, energetics, and the dynamic properties of the hydrocarbon molecule under the confinement of the chosen zeolite framework. The present thesis investigates the structural, energetic, and dynamic properties of three isomers of trimethylbenzenes (TMB), namely, 1,2,3-TMB, 1,2,4-TMB and 1,3,5-TMB, under the confinement of two structurally contrasting zeolites, namely, zeolite-ꞵ (BEA) and zeolite-NaY (FAU) through molecular dynamics simulations at different temperatures. zeolite-ꞵ (BEA) is a channel type porous framework consisting IV of straight channels along x and y-axes, tortuous channels along z-axis, whereas zeolite-NaY (FAU) is a cage type framework, consisting of large super cages separated by 12MR ring (12 Oxygens) windows. The results from our molecular dynamics simulations indicate that the 1,2,4- TMB diffuses faster than the other two in both the zeolites, whereas 1,3,5-TMB is strongly confined particularly in zeolite-ꞵ at all temperatures. The activation energies calculated from Arrhenius relation indicate that the 1, 3, 5-TMB encounters a relatively large energy barrier for translation as compared to the other two, in both the zeolites, however, the absolute entropies calculated from two-phase thermodynamics (2PT) method indicates that the associated translational barrier is purely entropic in nature. Rotational dynamics of these isomers has been studied through the time decay of Legendre polynomials corresponding to the autocorrelation of two chosen unit vectors, namely, a vector on the plane of the phenyl ring and a vector perpendicular to the plane of the phenyl ring representing the in-plane and out-of-plane rotations, respectively. In-plane rotations of 1,2,3-TMB are more facile than those of 1,2,4-TMB in both the zeolites while the out-of-plane rotations are largely hindered in 1,2,3-TMB than in 1,2,4-TMB. The in-plane and out-of-plane rotations are severely hindered for 1,3,5- TMB in both the zeolites. Therefore, our results demonstrate that the three isomers of the trimethylbenzene are distinguishable in their structure, energetic and dynamic properties under the confinement of zeolite-ꞵ and zeolite-NaY. We are confident that these results will be helpful in designing a zeolite-based separation technique.