One-Step Synthesis and Characterization of La₂NiO_4+δ Mixed-Conductive Oxide for Oxygen Permeation

Abstract

A one-step process for the synthesis of La2NiO4+ δ (LNO) mixed-conductive oxide was reported. During the process, LNO powders were synthesized via the combustion of mixtures with the desired metal ions as cation precursors and glycine as fuel. X-ray diffraction (XRD), scanning electron microscopy (SEM), dilatometry, and specific surface area analysis were used to characterize the crystal structures, morphologies, sintering behavior, and surface area of the LNO powders. The effect of the fuel ratio (Φ) on the crystal structures of LNO oxide was studied to reveal the optimal synthesis conditions. It was determined that almost-pure LNO oxide with a K2NiF4-type phase could be achieved when Φ = 1.2 without calcination steps. The synthesized LNO powders had good sintering properties, and the membranes derived from the powders could become dense after sintering in air at 1423 K for 5 h. The LNO powders possessed more interstitial oxygen ions in the rock-salt layers of LNO lattice than those derived from the traditional solid-state reaction (SSR) method. The oxygen permeability of the LNO membrane was examined by a high-temperature oxygen permeation measurement. The oxygen permeation flux (at 1173 K and the oxygen partial pressure gradient is 0.21 × 105/1 × 102 Pa) of the LNO membrane originated from combustion process was 1.5 × 10-7 mol cm-2 s-1, which was 1.5 times greater than that of the SSR-derived membrane.

Oxidative Steam Reforming of Raw Bio-Oil over Supported and Bulk Ni Catalysts for Hydrogen Production

“…The X-ray diffractogram of the fresh NiAl2O4 catalyst shows diffraction peaks corresponding to two different Ni species, NiAl2O4 and NiO, in agreement with the TRP profile in Figure 2 The only phase observed in the X-ray diffractogram of the LaNiO 3 perovskite prior to reduction is LaNiO 3 (Figure 4), which evidences the efficiency of the auto-combustion method used for obtaining this catalyst. Nevertheless, in the X-ray diffractogram of the La 2 NiO 4 perovskite, the presence of La 2 O 3 species is observed, together with La 2 NiO 4 , which could be due to the need of a higher calcination temperature or to a defect in the amount of the fuel (glycine) in the synthesis by auto-combustion, which hampers the compete combustion reaction [56]. After the reduction of both perovskite-type catalysts, the only species observed are Ni 0 and La 2 O 3 .…”

A review of recent developments in carbon capture utilizing oxy-fuel combustion in conventional and ion transport membrane systems

“…The source of fast O 2 transport in the K 2 NiF 4 materials is via interstitial O 2 transport through the Ln 2 O 2 bilayers [79]. These perovskites can selectively separate O 2 from air at elevated temperatures typically higher than 7001C, as shown in Figure 9(c) [3,80,81].…”

“…The values for J O2 [81,89,91] and tracer O 2 diffusion coefficients (D Ã ) [92][93][94] are plotted in Figures 11(a) and (b), respectively for LSCF6428, BSCF5582 and LNO. J O2 values for these three materials are found to be in the order of BSCF55824LNO4LSCF6428 and follows the same trends for D Ã .…”

Electrochemical performance of Nd1.8Ce0.2CuO4±δ mixed-ionic–electronic conductor for intermediate solid oxide fuel cells

“…Consequently, the mixed-ionicelectronic conductors (MIECs) have currently attracted a great deal of attention. Many mixed oxides of the form A 2 BO 4 (A = rare earth, and alkaline earth; B = transition metal) crystallized with the tetragonal K 2 NiF 4 -type structure (space group I4/mmm) have received renewed interest due to adequate oxygen ion conduction, strong electrocatalytic activity towards the oxygen reduction and the compatible TECs with those of the conventional electrolytes [5,6]. Although the total conductivity and the TEC of La 2 − x Sr x CuO 4 ± δ have been fairly satisfactory, they exhibit rather high area-specific resistance (ASR) [7,8].…”