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，将由两种不同的催化材料制备分级结构的多孔层状系统。这些系统旨在通过利用来自两种不同类型的活性中心的局部邻域的协同作用以及通过将两个工艺步骤合并为一个步骤来实现两步反应序列的良好实施。以甲醇为中间体，由合成气直接制取二甲醚是目前的研究热点。在该反应序列中，在A位置形成的甲醇立即进一步反应为在邻近位置B的二甲醚的转化率高于在A类型位置形成的唯一甲醇的转化率。为了实现这一点，除其他概念外，将通过定向方法制备尺寸在20至100微米范围内的核壳颗粒。这些颗粒由以铜/氧化锌/氧化铝为核心的甲醇合成催化剂组成，包裹在由ZSM-5型沸石晶体组成的规定厚度的多晶壳中，用于甲醇脱水。作为替代系统，将研究附着在平壁上的双层结构以及在公共球形ZSM-5基质中具有多个铜/氧化锌/氧化铝核心的微粒大小范围内的多核-壳结构。所制备的材料将通过多种方法进行全面的表征，以直观地显示其结构、形貌和化学组成，甚至在局部分辨率下，并探索其催化性能。获得的数据将被用于创建详细的模拟模型，这些模型将被用于优化分层结构，以实现最大的产品选择性或产量。模型中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还将用于根据费托工艺在Co/Al_2O_3催化剂上合成长链碳氢化合物，然后在沸石催化剂(如ZSM-5)上进行加氢裂解，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.