Synthesis of Pt/mesoporous SiC-15 and its catalytic performance for sulfuric acid decomposition

Abstract

Sulfuric acid (SA) decomposition is one of the key reactions in the sulfur-iodine (SI) cycle to produce hydrogen. Catalysts for the SA decomposition should be active and stable in a wide temperature range of 550–850°C to absorb latent heat generated from a thermal solar heat or a very high temperature nuclear reactor. Here, mesoporous mSiC-15 is prepared using the SBA-15 template. TEM analysis shows that the morphology of the mSiC-15 has the replica structure of SBA-15. Pt/SBA-15 and Pt/mSiC-15 catalysts are prepared by impregnation and the catalytic activity is examined under the reaction condition of 650–850°C and a GHSV of 76,000mL/gcat/h. The Pt/mSiC-15 catalyst is relatively stable for 50h at 850°C, while the Pt/SBA-15 was severely deactivated. The Pt amounts on the Pt/SBA-15 and Pt/mSiC-15 catalysts decreased from 0.73 and 0.80wt% at initial reaction time to 0.39 and 0.68wt% after 12h reaction, respectively. The Pt loss during the SA reaction is main cause of deactivation, which is caused by the evaporation of Pt oxides under O2 environment produced during the SA decomposition. It is observed that the Pt particles are embedded in porous SiO2 (Pt/mSiO2), which is transformed from Pt/mSiC-15 during the SA decomposition for 6h. The Pt/mSiC-15 was relatively active and stable for the SA decomposition and the Pt loss was minimized by the structural change from Pt/mSiC-15 to Pt/mSiO2 after 6h.