Novel polyhedral@ <scp> SiO ₂ </scp> core–shell catalysts designed for Fischer–Tropsch synthesis

BACKGROUND Fischer-Tropsch synthesis (FTS) has attracted much more attention for converting syngas to liquid fuels. Enhanced catalytic stability and excellent product selectivity can be achieved by rational design of catalysts. However, the traditional SiO2-supported Fe-based catalysts displayed higher interaction between active metal and SiO2 support, thus resulting in a lower catalytic activity. Rational design of catalysts with lower Fe-Si interaction promise an excellent catalytic performances. RESULTS In this paper, novel polyhedral@SiO2 core-shell catalysts with adjustable shell thickness were prepared. The incorporation of SiO2 shell with suitable thickness can maintain the integrity of active structure, and thus promises an excellent C5+ productivity combined with a higher catalytic activity. On the other hand, the SiO2 layer can prolong the residence time of CnHm intermediates on the active surface of Fe particles that enhance the C-C coupling reaction, favoring chain growth for production of C5+ yield. However, excessive addition of TEOS cannot increase the shell thickness in the absence of ammonium hydroxide and can responsible for a poor CO conversion. Si-66 with shell thickness of 66 nm achieves an optimum C5+ yield of 2.23×10-3 gHCgFe-1s-1 and a higher FTY value of 31.5 μmolCOgFe-1s-1. Obviously, this C5+ yield is comparable to the Mn-promoted FeSiMn catalyst (2.22×10-3 gHCgFe-1s-1) in our previous work. CONCLUSION SUBHEADINGS It revealed that introduction of SiO2 as shell can improve the structural stability during FTS. Moreover, the novel polyhedral@SiO2 core-shell catalyst exhibits excellent C5+ yield, and which is 1.8 times higher than spindle@SiO2 core-shell catalyst in our previous work. This article is protected by copyright. All rights reserved.