Novel polymer-MOF nanocomposite membranes are prepared via the incorporation of ZIF-8 nanocrystals into cardo polyetherketone (PEK-c) for pervaporation separation of water/methanol/MTBE ternary mixtures. The ZIF-8 nanocrystals with 20-40 nm size are synthesized for preparing membranes. The resulting membranes have ZIF-8 nanocrystals dispersed homogeneously and embedded in the membrane matrix with adjustable ZIF-8 loading of up to 20 wt%. Moreover, the membranes have homogeneous microstructure, good thermal and mechanical stabilities. They show favorable pervaporation performances for separation of the water/methanol/MTBE mixtures. The incorporation of ZIF-8 greatly enhances the permeation flux. At the low ZIF-8 loading, the water selectivity increases and the total separation factor is very high and greater than 1.97 x 10(4). Typically, the membrane with 4wt% ZIF-8 has the total flux of 1.48 kg mu m m(-2) h(-1), water and total separation factor of 181 and 1.97 x 10(4) respectively. The newly developed nanocomposite membranes have a great potential in high-efficient purification of MTBE. (C) 2016 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.