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

通过使用纳米技术，将从两种不同的催化材料制备分级结构的多孔层状系统。该系统旨在通过利用两种不同类型的活性位点的局部邻域的协同作用以及将两个工艺步骤合并为一个来实现两步反应序列的有利实施。以甲醇为中间体，由合成气直接生产二甲醚是目前研究的热点。在该反应顺序中，在位点A处形成的甲醇在相邻位点B处立即进一步反应为二甲醚，产生比在类型A的位点处单独形成甲醇更高的转化率。为了实现这一点，除其他概念外，将通过靶向方法制备尺寸范围为20至100微米的核-壳颗粒。所述颗粒由作为甲醇合成催化剂的Cu/ZnO/Al 2 O 3核组成，所述核被具有限定厚度的多晶壳包封，所述多晶壳由用于进行甲醇脱水的ZSM-5型沸石晶体制成。作为替代系统，将研究附着于平壁的双层结构以及在具有多个Cu/ZnO/Al 2 O3核的微粒尺寸范围内的多核-壳结构。所制备的材料将通过多种方法进行彻底表征，以可视化其结构，形态和化学组成，甚至具有局部分辨率，并探测其催化性能。获得的数据将用于创建详细的模拟模型，该模型将用于优化分层结构，以实现最大的产品选择性或产率。来自建模的预测最终将通过专门的准备和表征来判断。为制备材料而开发的概念也将用于根据费托法在Co/Al 2 O3催化剂上合成长链烃，然后在沸石催化剂例如ZSM-5上加氢裂化烃以生产汽油、煤油或柴油产品，以研究该方法的可移植性。

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.