Use of Perovskite-Type Lanthanum Nickelate Synthesized by the Polymeric Precursor Method in the Steam Reforming Reaction of Methane

Abstract

In the current work, LaNiO<sub>3</sub> perovskite was synthesized using the polymeric precursor method. The materials were thermally treated at 300°C for 2 hours, subsequently supported on alumina or zirconia and finally calcined at 800°C for 4 hours. The resulting samples were characterized by X-ray diffraction, thermogravimetry, BET surface area and thermo-programmed reduction. Steam reforming reactions were carried out at 750°C and 6 bar during 4 hours using a pilot reactor under a H<sub>2</sub>O:CH<sub>4</sub> ratio of 2.5. The mass of catalysts was about 5.7 g. X-ray diffraction patterns confirmed the formation of the perovskite structure in all samples prepared. The results also showed that lanthanum nickelate was more efficient when supported on alumina than zirconia. Finally, it was observed that the methane conversion was approximately 94% and the selectivity to hydrogen was about 70%. In all cases low selectivity to CO and CO<sub>2</sub> was verified

Effects of Concentration, Crystal Structure, Magnetism, and Electronic Structure Method on First-Principles Oxygen Vacancy Formation Energy Trends in Perovskites

“…Transition metal perovskite (ABO 3 ) oxides are used in applications that include gas sensors, 1,2 photovoltaics, 3 spintronics and other forms of magnetic coupling, 4,5 exhaust gas CO 6,7 and NO x 8−10 treatment, and steam reformation. 11,12 In the context of redox reactivity, these oxides are utilized in two primary fields of research, namely, clean energy and catalysis. With respect to clean energy, transition metal oxides function as cathode materials to improve the oxygen reduction reaction (ORR) kinetics of solid oxide fuel cells (SOFCs), 13,14 while they serve as oxygen carriers in chemical looping combustion (CLC) processes 15,16 intended for applications in power generation coupled with carbon capture and storage (CCS).…”

“…13 Furthermore, perovskites such as (La,Sr)MnO 3 (LSM) and (La,Sr)MnO 3 (LSF) are also chemically stable over a wide range of redox reaction conditions 21,30 and are compatible with multiple substrate support materials such as yttria-stabilized zirconia (YSZ) and alumina (Al 2 O 3 ). 16,18 LaBO 3 materials with B-site cations comprised of 3d transition metals with partially filled d-shells (B = Sc−Cu) have favorable structural, 9,24,31 electronic, 7,16 and catalytic 11,32,33 properties over the range of thermodynamic temperature 34,35 and pressure 36,37 conditions appropriate for redox reaction applications. 17,25,38,39 In redox applications, these LaBO 3 materials must observe not only favorable bulk and surface redox reactivity but also favorable ionic and electronic migration properties.…”

“…LaBO 3 materials with B-site cations comprised of 3d transition metals with partially filled d-shells (B = Sc–Cu) have favorable structural, ,, electronic, , and catalytic ,, properties over the range of thermodynamic temperature , and pressure , conditions appropriate for redox reaction applications. ,,, In redox applications, these LaBO 3 materials must observe not only favorable bulk and surface redox reactivity but also favorable ionic and electronic migration properties . The transport of oxygen anions and electrons from bulk to surface facilitates the transformation between energetically stable bulk and surface structures containing oxygen vacancies, allowing the mechanisms of surface and bulk oxygen vacancy formation to cooperatively contribute to redox reactivity. , In these mechanisms, the facile reduction and oxidation of 3d transition metal B-sites located on the perovskite surface is enabled by their multiple available valence states, allowing local conservation of charge in the presence of substantial surface oxygen vacancy concentrations. , Many LaBO 3 materials observe favorable oxygen transport properties, such as consistently low migration energies associated with oxygen diffusion from surface to bulk, , displacement of A- and B-site cations away from the diffusion paths of oxygen, the presence of several open diffusion paths between different oxygen crystallographic sites, and sufficient concentrations of mobile oxygen anions .…”

“…Transition metal perovskite (ABO 3 ) oxides are used in applications that include gas sensors, , photovoltaics, spintronics and other forms of magnetic coupling, , exhaust gas CO , and NO x − treatment, and steam reformation. , In the context of redox reactivity, these oxides are utilized in two primary fields of research, namely, clean energy and catalysis. With respect to clean energy, transition metal oxides function as cathode materials to improve the oxygen reduction reaction (ORR) kinetics of solid oxide fuel cells (SOFCs), , while they serve as oxygen carriers in chemical looping combustion (CLC) processes , intended for applications in power generation coupled with carbon capture and storage (CCS). − Particular to chemical looping processes, unmixed oxygen carriers possess strong thermodynamic properties, enabling effective redox reactivity in various physical implementations of such processes. ,, Though their oxygen transport properties are characteristically poor relative to this level of reactivity, the mixture of cations on several of the sites of these oxygen carriers has been demonstrated to improve oxygen transport properties significantly without significantly lowering redox reactivity. − With respect to catalysis, mixed-metal perovskite solutions are frequently used to tune and optimize operating parameters in hydrocarbon oxidation processes , including fuel conversion, ,, CO 2 selectivity, and specific surface area , relative to other reaction parameters.…”

Engineering the Solid Oxide Fuel Cell Through Infiltrating the Porous Electrodes

“…The cathode side helped to have a high oxygen reduction activity and the anode side helped with catalytic activity.The problem with using this material as an anode is that it is known to dissociate into Ni/La2O3 upon reduction. Martinelli impregnated LaNiO3 into alumina or zirconia and calcined at 900 C for 4 hours 33. They found the complete reduction of LaNiO3 to La2O3 to occur at around 520 C. When there was no support present in the form of either alumina or zirconia there was a rapid deactivation of the catalysts.…”