Experimental and Computational Studies of Perovskite Oxygen Carrier Materials for CO2 Separation

Abstract

This dissertation is dedicated to Experimental and Computational Studies of Perovskite Oxygen Carrier Materials for CO2 Separation.Energy is basic need of this hour. The combustion of natural sources like fossil fuels produce hazardous gases like CO2. The concentration of CO2 in air is the main cause of depletion of ozone layer and climate effects. To overcome this problem, Chemical looping combustion CLC is a very promising technique. In this project, we synthesize perovskite oxygen carrier materials for the separation of CO2.The proposed materials are Iron-based strontium manganese oxide (FeSrMnO3), where (x = 0.1, 0.3, 0.5 , 0.7 , 0.9 ) are prepared by using solid state reaction method. Different characteristics of perovskite oxygen carrier materials FexSr1-xMnO3 are studied in this project like X-ray’s diffraction (XRD), Raman spectroscopy, Fourier Transformation Infrared Spectroscopy (FTIR), Thermogravimetric analysis (TGA), Scanning electron microscopy (SEM) and some theoretical studies like Density Functional Theory (DFT). The XRD pattern of (FeSrMnO3), where (x = 0.1, 0.3, 0.5, 0.7, 0.9 ) represents the same pattern which is tetragonal with reference code JCPD NO: 00-051-1860. The average crystalline size is 946, 765, 780 ,550 and 642 respectively. Raman spectra of all samples FexSr1-xMnO3 show prominent bands at 132, 190, 432, 527, 648, 796, 895 and 980 cm-1 related to Fe-O vibration, symmetric stretching vibration of metal oxygen chain of Mn-O-Mn O, symmetric and asymmetric stretching vibration of Sr-O band, T2g mode, transverse, longitudinal and two phonons optical (2LO) modes. FTIR spectra of all samples of FexSr1-xMnO3 show the peaks at 608, 770 – 900, 968, 1078, 1173, 1365 , 1491 , 3500-4000 cm-1 vibrational modes of Sr O, Mn-O stretching vibrations , Fe-O nanoparticles , vibrations among O-O bonding and OH-functional group or the presence of adsorbed water molecules. Surface morphology of prepared composite materials is studied by Scanning Electron Microscopy (SEM) (homogenous and porous structure). The DFT calculations of FexSr1-xMnO3 tells about the structure which shows both cubic and hexagonal, DOS (Electronic Density of states) tells about the properties of metals and we can find xiii band gap of the material. The material shows metallic nature because no band gap is observed in prepared oxygen carrier material