New methods to prepare perovskite-type La_0.8Sr_0.2CoO₃ catalyst at low temperature

A pure phase perovskite-type composite oxide La_0.8Sr_0.2CoO₃ (LSCO) was prepared by three methods: sol-gel method using EDTA as ligand, environmentaly safe metal-EDTA-cellulose complexing method and metal-citric-cellulose complexing method. The formation processes of LSCO by those methods were investigated by TG-DTA, XRD and IR spectroscopy. The results indicated that when EDTA complexing method was used, at optimized condition, pure phase perovskite-type LSCO was acquired after the precursor was fired at 800°C for 2hr. In the process of forming perovskite LSCO, SrCO₃ was formed and calcination temperatures higher than 800°C was needed to get rid of it, similar to the citric complexing method reported. When cellulose was introduced, the minimum calcination temperature to acquire pure phase LSCO was significantly lowered to around 600°C for metal-EDTA-cellulose method and 540°C for metal-citric-cellulose method. Low calcination temperature led to relatively high BET area for 21m²/g and 22m²/g respectively. But the surface area were significantly reduced to 12.7m²/g and 12.1m₂/g respectively when they were further fired at 620°C for 2hr.