Nanofibrous perovskite ceramics with in-situ exsolved Ni3Fe alloy nanoparticles for catalytic CO2 methanation

Exsolution is a promising method to prepare highly-dispersed and stable nanocatalysts, while exsolution efficiency is limited by the high temperature crystallization of parent perovskite ceramics, which leads to the low surface area of parent oxides for exsolution. The fibrous structure of ceramics shows highly-thermal stability, and this study employed the thermally-stable structure to realize the high efficiency of exsolved nanocatalysts from perovskites. Sr0.95Ti0.3Fe0.55Ni0.15O3-delta nanofibrous perovskites catalysts were prepared by electrospinning and subsequent calcination and reduction. The amount of exsolved Ni3Fe alloy nanoparticles increased with calcination temperature up to 1075 degrees C while the catalysts retained the nanofibrous structure. Further increasing calcination temperature to 1100 degrees C caused catalyst agglomeration. The Ni dissolution was also optimized by tuning the amount of Ni-doping to maximize catalyst activity. The nanofibrous catalysts demonstrated high and stable performance in CO2 methanation, and achieved the CO2 conversion and CH4 selectivity of 70.5% and 94.4% at 450 degrees C. Therefore, the merits of exsolution method have been realized over the nanofibrous perovskite catalysts.