Bifunctional hierarchically-structured porous layered systems for efficient one-step conversion of synthesis gas to fuels in microstructured reactors

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Through the use of nanotechnology, hierarchically structured porous layered systems will be prepared from two different catalytic materials. The systems are meant to achieve a favorable implementation of two-step reaction sequences via utilization of synergies from the local neighborhood of the two different types of active sites, as well as from merging two process steps into one. Direct production of dimethyl ether from synthesis gas via methanol as an intermediate is in the focus. In this reaction sequence, immediate further reaction of methanol formed at site A to dimethyl ether at the neighboring site B yields higher conversion as for sole methanol formation at sites of type A. To achieve this, among other concepts, core-shell particles in the size range of 20 to 100 microns will be prepared by targeted approaches. The particles consist of a Cu/ZnO/Al2O3 core as methanol synthesis catalyst encapsulated by a polycrystalline shell with defined thickness made up from zeolite crystals of ZSM-5 type for performing methanol dehydration. Double layer structures attached to a flat wall as well as multicore-shell structures in the size range of microparticles having multiple Cu/ZnO/Al2O3 cores within a common spherical ZSM-5 matrix will be studied as alternative systems. The prepared materials will be characterized thoroughly by multiple methods to visualize their structure, morphology and chemical composition even with local resolution, and to probe their catalytic performance. The data obtained will be used to create detailed simulation models, which will be adopted to optimize the layered structures towards maximum product selectivity or yield. The predictions from the modeling will ultimately be judged by dedicated preparation and characterization. The concepts developed for preparation of the materials will also be used for synthesis of long chained hydrocarbons on Co/Al2O3 catalysts according to the Fischer-Tropsch process, followed by hydrocracking of the hydrocarbons on zeolite catalysts, e.g. ZSM-5, to produce gasoline, kerosine or diesel products in order to study the portability of the approach.