Perovskite LaNiO₃ Nanocrystals inside SBA‐15 Silica: High Stability and Anti‐Coking Performance in the Pre‐Reforming of Liquefied Petroleum Gas at a Low Steam‐to‐Carbon Molar Ratio

Abstract

Ah igh loading of LaNiO 3 perovskite nanocrystals (83 wt %) was successfully incorporated inside the orderedm esoporous framework of SBA-15s ilica by ac itric acid assisted impregnation method.T he obtained LaNiO 3 /SBA-15 material produced both La 2 O 3 nanoparticles andm etal Ni nanoparticles with intimate contact and highly dispersed in the mesoporousS BA-15 framework upon reduction with H 2 ,a nd it showed high activity,h igh stability,a nd good anti-coking ability for the low-temperatures team reforming of liquefied petroleumg as at al ow steam/carbon ratio of 1.0. The excellent performance of the LaNiO 3 /SBA-15 materialw as attributed to the formationo fs ynergistic active sites in the interfacial area, which consisted of metal Ni andL a 2 O 2 CO 3 species, and the confinement effect of the mesoporous structure on the Ni and La 2 O 3 species.Nickel-based catalysts have been widely investigated for the production of synthesis gas and hydrogen through various reforming processes of hydrocarbons because of their high intrinsic catalytic activity and low cost.[1-4] However,t raditionalN i catalysts suffer from severe deactivation resulting from coke deposition and sintering of the Ni particles and support. [5][6][7] Therefore, it remains an important challenge to develop novel Ni-based catalysts with improved stability to suppress coke deposition and thermalsintering. [8] It has been demonstrated that small Ni crystallites can reduce the rate of carbon deposition, and this resultsi nb etter catalytic stability for the reforming of hydrocarbons. [9][10][11][12] The preparation of stable nanosized Ni crystallites has been the key for developinge xcellent Ni catalysts. The so-called "solid-phase crystallization" method has recently attracteds peciali nterest as ap romising route to obtain good catalysts based on small metal particles dispersed on as upport. [13,14] Using this method, supported Ni nanocrystallites are obtained by in situ reduction of homogeneously distributed Ni ions in mineral-type crystalline solids, such as LaNiO 3 perovskites, [15] NiAl 2 O 4 spinels, [16] and Ni-Mg-O solids olutions.[17] The sintering of Ni crystallites can be efficiently suppressed by the presenceo fstrong metal-support interactions. Nevertheless, these supported Ni-based catalysts are frequently insufficient to meet the demands of the reaction because of low surfacea reas, which precludes dispersion of the active metals.S ome efforts have been devoted to introducing mineral-type nanocrystalsi nt he support with welldefined channels, as this offers not only ah igh surface area for the dispersion of active metals but also as patialr estriction on metal crystallites that hamper sintering.[18] However,t he controllable preparation of mineral-typen anocrystals in the support with an appropriate porous structure such as SBA-15s ilica remains challenging.Liquefied petroleum gas (LPG) is considered ap referred fuel for distributed hydrogen production for fuel-cella pplications owing to its easy storagea nd transportation and well...

Improving the Performance of BaMnO3 Perovskite as Soot Oxidation Catalyst Using Carbon Black during Sol-Gel Synthesis

“…SBA-15 mesoporous silica to be used as a hard template in the modified sol-gel synthesis method was synthesized by a soft-template route according to the literature [15,21,63]. Thus, silica is dispersed (1:10 ratio regarding deionized water) and added to the sol of the perovskite precursors (1:1 volume ratio) obtained by the route indicated in Table A1.…”

“…Among others, the nano casting technique allows the increase in the surface area using ordered mesoporous materials, as silica or carbon [9,18]. Interconnected structures facilitate the formation of a stable replica, and the pore structure and the particle morphology will depend on the selected material [10,14,15,[19][20][21][22].…”

Preparation of Highly Dispersed Ni-Ce-Zr Oxides over Mesoporous <i>γ</i>-Alumina and Their Catalytic Properties for CO₂ Methanation

“…In the case of the preparation process in the absence of CA, the molecules of metal nitrates without complexation could move freely in the host pores in the immobilized procedure because they had relatively lower melting points (56.7°C for Ni(NO3)2; 96°C for Ce(NO3)3). The metal nitrates moved towards the pore mouths and agglomerated at the pore mouths or on the exterior surface due to the capillary forces in the drying and heat-treating process, and finally produced larger metal oxide crystallites, blocking the pores of the support 20 .…”

“…Citric acid (CA) has frequently been chosen as a chelating agent of metal ions in the catalyst preparation because of its excellent ability to chelate metal ions [16][17][18][19] . The use of chelating agents has several implications in the material properties: morphology of active phase, dispersion of metal oxides in the support, and the promotion of highly active phases [20][21][22][23][24][25][26][27] .…”

Perovskite LaNiO3 Nanocrystals inside Mesostructured Cellular Foam Silica: High Catalytic Activity and Stability for CO2 Methanation

“…MCF‐supported perovskite LaNiO 3 nanocrystals (LaNiO 3 /MCF) were prepared by a citric acid–assisted impregnation method . The stoichiometric amount of citric acid, La(NO 3 ) 3 ·6H 2 O, and Ni(NO 3 ) 2 ·6H 2 O in a molar ratio of 3:1:1 was dissolved in deionized water (50 mL) at room temperature under stirring.…”