150nm pure silica ZSM-5 was synthesized and surface modified using a two step Grignard treatment. Mg(OH)2 Whisker was grown on the surface of ZSM-5 particles. Mixed matrix films were cast using a 6FDA-DAM polymer, with upto 35wt% GT-ZSM-5 loading. The permeability of n-Butane more than doubled and selectivity of butane isomers remained the same after adding 35wt% GT-ZSM-5, which means either too permeable ZSM-5 or bad interface. To find the cause, impermeable ZSM-5 particle with template inside pores was synthesized, GT modified and cast into composite membranes with upto 35wt% loading. The permeability of n-Butane decreased 30% at 35wt% loading, which agrees with Maxwell modeling with solid loading, thus proved the defect-free interface between ZSM-5 particles and Polymers. No polymer could match the high permeability of ZSM-5 to make promising composite membrane for butane isomers separation.