Pt-core silica shell nanostructure: a robust catalyst for the highly corrosive sulfuric acid decomposition reaction in sulfur iodine cycle to produce hydrogen

Abstract

The platinum core silica shell catalyst has facilitated stable sulfuric acid decomposition at high-temperature which was not possible over bare Pt nanoparticles due to sintering and agglomeration. Helium (He) gas supplies the heat (550–900 °C) in a high temperature gas cooled reactor (VHTR). The major challenge is designing a stable catalyst for the variable heat efficiency of He. Pt catalysts loaded on different supports, such as SiC, Al₂O₃, SiC-Al₂O₃, BaSO₄, TiO₂, SBA-15, and SiO₂, have been extensively studied but they have not provided a simple method to form robust catalysts for sulfuric acid decomposition. The core–shell scheme, whereby nanoparticles are enclosed by protecting agents (CTAB) and are covered by a silica shell, delivered mesopores and exhibited higher activity and stability over testing for more than 100 h. TEM images confirmed that the Pt particles on the Pt@mSiO₂ catalyst are more stable during sulfuric acid decomposition, and no significant evidence of agglomeration or sintering of the Pt core particles was found, despite some broken shells and dislocated Pt nanoparticles from the silica core. ICP-OES analysis of the spent catalysts after 100 h showed minimal Pt loss (9.0%). These types of catalysts are highly desirable for practical applications.