This invention establishes a novel post-synthetic route to make a new class of microporous materials with reduced diffusion limitations, referred to as "finned" zeolite crystals. Inspired by conventional fins which enhance interfacial heat transfer, finned zeolite crystals are comprised of a seed (with a characteristic size of �) and epitaxially grown protrusions (with a characteristic size of �, where � << �). The growth of protrusions is accomplished by a seeding method where zeolite crystals are placed in a growth solution that results in the formation of a roughened interface on the surfaces of the seeds. The growth solution and conditions of secondary synthesis were designed in such a way to minimize homogeneous nucleation of new crystals and preferentially grow fins on the crystal seeds. The conditions of secondary growth can be adjusted to vary the density (or coverage) and size of fins. This process is generalizable to a wide range of zeolite framework types. We have demonstrated the synthesis of finned zeolites on three different crystal structures: ZSM-5 (MFI), ZSM-11 (MEL), and ferrierite (FER). Both MEL and MFI frameworks are comprised of 3-dimensional intersecting medium-sized channels, whereas the FER framework is comprised of 2-dimensional intersecting small- and medium-sized channels. Reported methods in prior art to reduce diffusion limitations include the preparation of nano-sized (with sizes 10 – 100 nm) zeolites and 2-dimensional zeolites (with sizes of 2 -10 nm). Achieving such small sizes is often nontrivial and can involve multi-step processes that often involves the use of organic structure-directing agents (many of which are not commercially available). To this end, we have discovered the synthetic approach of finned zeolite crystals where catalytic tests reveal that the overall performance of these materials are similar to crystals with smaller sizes of approximately � (the finned protrusions). This indicates that the introduction of fins leads to improved catalyst properties and may also extend to other applications, such as separations or ion exchange, where internal diffusion can impact overall properties of the zeolite. The method of this disclosure relies on the post-synthesis modification of existing (seed) crystals. We have observed that fins can be generated via a one-pot process; however, the exact set of synthesis conditions is unpredictable, and is thus less generalizable to a broad set of crystal structures. The seeded growth approach is one that more reproducibly (and predictably) leads to finned materials. One of the difficulties of preparing finned zeolites is identifying growth mixtures that promote the nucleation and growth of protrusions on the surfaces of seed crystals. Systematic experiments in our lab have identified conditions that are optimal for finned zeolite formations. The conditions that can be manipulated to tailor finned zeolites include (but are not limited to) temperature, synthesis time, supersaturation (i.e. silica and/or alumina concentrations), the sources of silica and alumina, and alkalinity. For example, synthesis at high temperature may promote homogeneous nucleation of crystals that are isolated from the seed crystals, thus generating a biomodal distribution of crystal sizes (or aggregates of crystals). Conversely, synthesis at low temperature may be insufficient to nucleate new layers (i.e. protrusions) on the surfaces of zeolite seed crystals. It is well established that zeolite crystal size can improve catalyst lifetime (depending on reaction conditions), and can also influence product selectivity. Smaller dimensions lead to a reduction in the average residence time of reactants and products within the pores of the zeolite. This reduction in internal diffusion path length, for example, reduces the rate of coke formation (i.e. carbon deposits that block pores), thereby increasing the catalyst lifetime and potentially altering the number of secondary reactions taking place in the pores, which impacts selectivity. Our findings reveal that finned zeolites, despite having a net larger size than the seeds, behave as catalysts with sizes that are smaller than the seed. For these tests we selected the methanol to hydrocarbons (MTH) reaction and showed a nearly three-fold decrease in the rate of catalyst deactivation relative to conventional zeolite crystals. We also observed a shift in the mechanism for finned zeolites that resulted in product selectivities similar to smaller crystals. Collectively, our findings indicate that this novel modification method enhances catalyst performance (reported in this disclosure for both MFI and MEL catalysts), thus offering an efficient and versatile platform to synthesize optimal zeolite catalysts with reduced diffusion limitations for diverse applications in the (petro) chemical industry. This method also allows for the modification of existing commercial catalysts through a facile secondary growth procedure.