Easy precipitation method for preparation of cerium added La_2O_2SO_4 used for oxygen storage

摘要

The present work gives a simple precipitation method for preparation of lanthanum oxysulfate and cerium modified lanthanum oxysulfate by using lanthanum nitrate and ammonium sulfate as precursor in the presence of ammonia. The XRD, TEM, XPS, and N_2 sorption measurements have been adopted to characterize those materials. The present work demonstrates that cerium addition can promote the oxidation and reduction process between lanthanum oxysulfide(La_2O_2S) and lanthanum oxysulfate (La_2O_2SO_4). The cerium doped La_2O_2SO_4/La_2O_2S oxygen storage system showed the replacement of cerium for some La site to form a stable structure and no sulfur leakage took place in the process of redox cycle. The oxidation temperatures of Ln_2O_2S to Ln_2O_2SO_4 decrease more than 150 °C for cerium doping samples; and the reduction temperature of La_2O_2SO_4 to La_2O_2S in hydrogen decreases about 50 °C. The redox cycle between Ce~(3+) and Ce~(4+) has been considered response to the promotion of the redox cycle.