Safari Masoud, Haghtalab Ali, Roghabadi Farzaneh Arabpour
Faculty of Chemical Engineering, Department of Process, Tarbiat Modares University P.O. Box: 14115-143 Tehran Iran
RSC Adv. 2023 Aug 1;13(33):23223-23235. doi: 10.1039/d3ra04884e. eCollection 2023 Jul 26.
To enhance the catalyst performance of Fischer-Tropsch synthesis (FTS), removing the mass-transfer restriction in the catalysis synthesis is essential. Although the core-shell nanostructures can improve the activity and stability of the catalyst, they can restrict the reactants' diffusion towards the active sites and the transfer of the products from these sites in FTS. Creating an adequate porosity between the core and the outer shell of the catalyst structure can tackle this issue. In this work, the synthesized cobalt-based nano-catalyst is encapsulated with two shells and a middle porous shell. The first shell is a carbon shell at the core of the catalyst derived from ZIF-67, the second one is the outer shell of ceria, and the middle porous shell is formed by removing the sacrificial silica shell through the etching technique. The characterization and performance tests represent significant evidence of the etching treatment's impact on the FTS catalyst performance. Besides, molecular dynamics simulation is also utilized to clarify its effect. The FTS catalytic performance is enhanced more than 2 times with the etched catalyst the catalyst without it at 17.5 bar and a (H/CO) ratio of 1.2. In addition, not only does the etched catalyst with high porosity play the role of a nanoreactor and intensify its catalytic performance, but it also has higher stability.
为提高费托合成（FTS）的催化剂性能，消除催化合成中的传质限制至关重要。尽管核壳纳米结构可以提高催化剂的活性和稳定性，但在费托合成中，它们会限制反应物向活性位点的扩散以及产物从这些位点的转移。在催化剂结构的核与外壳之间创造足够的孔隙率可以解决这个问题。在这项工作中，合成的钴基纳米催化剂被包裹有两层壳和一个中间多孔壳。第一层壳是源自ZIF-67的位于催化剂核心的碳壳，第二层是二氧化铈外壳，中间多孔壳是通过蚀刻技术去除牺牲性二氧化硅壳形成的。表征和性能测试表明了蚀刻处理对费托合成催化剂性能影响的重要证据。此外，还利用分子动力学模拟来阐明其效果。在17.5巴和（H/CO）比为1.2的条件下，蚀刻后的催化剂的费托合成催化性能比未蚀刻的催化剂提高了2倍多。此外，具有高孔隙率的蚀刻催化剂不仅起到纳米反应器的作用并增强其催化性能，而且还具有更高的稳定性。
