Fischer-Tropsch synthesis (FTS) is a key technology for the production of liquid fuels from syngas. Enhanced liquid fuel production and catalytic stability can be achieved by rational design of catalysts Due to the metal-promoter interaction, conventional Mn-modified ion-based catalysts showed high C-2 through C-4 olefin selectivity and low activity. In this paper, Mn-containing SiO2-encapsulated ion based double-shell spindles were fabricated and employed as a FTS catalyst. For the proposed design, the SiO2 shell not only is employed as an interlayer to weaken the contact between Fe and the Mn promoter, but also acted as the anchoring site for Mn nanoparticles. The results showed that the Mn-modified FeSiMn catalyst presents higher catalytic activity (3.41 x 10(-5) mol(co) g(Fe)(-1) s(-1)) and superior C5+, production (20.8 x 10(-4) g(HC) g(Fe)(-1) s-1) compared to the unmodified FeSi catalyst. This can be ascribed to the Mn-improved spillover effect. Thus, design of double-shell catalysts provides important clues for understanding the sole effect of the promoter on catalytic performance and for improving the production of liquid fuels. (C) 2017 Elsevier Inc. All rights reserved.