The Research Of La-Ni-O Catalysts On Partial Oxidation Of Methane To Syngas

The single-phase perovskite oxide, LaNiO3, had been prepared by decomposing of mixed nitrate with various content of chelating agent after being pre-calcined at air for 2 h and calcination under O₂ atmosphere at 750℃for 4 h, over which the application for partial oxidation of methane to syngas has been investigated. Various addition of citrate acid to the sol-gel system may affect the morphology and catalytic preformance of LaNiO3 catalysts as well obviously. BET and SEM studies showed that the specific surface area increase with increase of citrate acid amount, and the exterior morphology of the samples changed from network structure, via sheet, to accumulative structure. EDS analysis revealed that La:Ni:CA=1:1:3 sample has the relative low surface nickel content and lattice oxygen, which may favor the transportation of the lattice oxygen and foreign oxygen under high temperature and thus probably make a certain contribution to the well catalytic activity.The research on NiO/La₂O₃ revealed that the provskite structure of LaNiO3 can be formed after calcinations at high temperature. The influences of calcinations temperature, space velocities, molar ratio of feed gases, nickel content and also reaction temperature have been investigated. Compared to other samples with various nickel content, the 30%NL catalyst sample being calcined at 500℃for 4 h was proved to be the most active for the partial oxidation of methane to syngas with CH₄:O₂:N₂ = 2:1:4 (vol%) under atmospheric pressure. High activity with high resistance to coke of the 30%NL sample was confirmed by obtaining high CH4 conversion and CO selectivity over 6 h and 100 h reacions respectively. XPS and TG studies showed that the large amount of La2O₂CO3 formed during reaction probably a C-containing species, a kind of oxycarbonate, which may favor removal of excess carbon deposition and impart the catalyst its stability characteristics.Catalytic oxidation of methane to syngas is one of the most effective methods of utilization in recent years, according to which we designed and then prepared NiO/La₂O₃ and LaNiO₃ catalyst respectively in this paper. By the characterization of BET, XRD, TPR, TG/DTA, SEM, XPS, EDS and activity evaluation, the physico-chemical properties and catalytic performance of the catalysts were investigated systematically.