Showing papers by "Zongping Shao published in 2000"
TL;DR: In this article, a combined citrate-EDTA complexing method was used for the preparation of SCFO and Ba0.2O3-delta (BSCFO) oxides, and the results of O-2-TPD and XRD showed that the introduction of barium into SCFO could effectively suppress the oxidation of Co3+ and Fe3+ to higher valence states of Co4 and Fe4+ in the lattice and stabilize the perovskite structure under lower oxygen partial pressures.
978 citations
TL;DR: In this article, perovskite-type B-site Bi-doped BaBi x Co 0.2 Fe 0.5 O 3− δ membrane was investigated in a wide temperature range from 600°C to 950°C.
99 citations
TL;DR: In this article, the adsorption properties of cellulose were investigated in the preparation of nano-crystal LSCO oxide powder, and the results showed that cellulose could successfully reserve the homogeneity of the solution system to the solid precursor.
Abstract: La0.8Sr0.2CoO3 (LSCO) oxide powder was prepared using the adsorption properties of cellulose. The preparation process was studied by XRD, FTIR, TG-DTA and CO2-TPD techniques. The results of XRD, IR and TG-DTA testified that cellulose could successfully reserve the homogeneity of the solution system to the solid precursor. During the early stage of pyrolysis, cellulose was partially oxidized, and some COO− groups appeared in its texture, which were then complexed with the adsorbed metal ions, and effectively suppressed the aggregation of metal ions. Formation of a pure perovskite and the properties of the powder resulted were found to be significantly influenced by the cellulose to metal nitrate ratio. Also the properties of the resulting powder were greatly influenced by the calcination conditions. If the produced carbon dioxide could not be eluted in time, carbonate would be formed in the bulk. Hence, a high calcination temperature (>800°C) was needed to acquire a pure phase LSCO. At optimized conditions, nano-crystal LSCO could be obtained at as low as 500°C.
27 citations
TL;DR: In this article, a mixed-conducting membrane with high oxygen permeability and promising stability was developed for the partial oxidation of methane to syngas reaction using air as the oxygen source.
Abstract: Mixed-conducting oxygen permeable membranes represent a class of novel ceramic membranes, which exhibit mixed oxygen ionic and electronic conductivities. At high temperatures, oxygen can permeate through the membrane from the high to low oxygen pressure side under an oxygen concentration gradient. Theoretically, the permselectivity of oxygen is 100%. Recently, a novel mixed-conducting membrane—Ba0.5Sr0.5Co0.8Fe0.2O3−δ has been developed, which shows extremely high oxygen permeability and promising stability. Furthermore, the reactor made with such membranes was successfully applied to the partial oxidation of methane to syngas reaction using air as the oxygen source, which realized the coupling of the separation of oxygen from air and the partial oxidation of membrane reaction in one process. At 850°C, methane conversion > 88%, CO selectivity > 97% and oxygen permeation rate of about 7.8 mL/(cm2 · min) were obtained.
16 citations
TL;DR: In this paper, the oxygen permeation flux is determined mainly by the oxygen diffusion rate in bulk when 1-x⩽0.5 and by the concentration of oxygen vacancy when 1 −x ⩾ 0.5.
Abstract: SrxBi1-xFeO3-δ (SBF) series mixed conductors were synthesized using standard ceramic method. The properties of such materials were characterized by XRD, O2-TPD techniques. Abnormal crystal phenomena were found and explained and correlated with the oxygen permeation results. By analysis of the critical radius (rc), the degree of openness of the lattice (Fv) and the average metal-oxygen bonding energy of the perovskite lattice (ABE), it was proposed that the oxygen permeation flux is determined mainly by the oxygen diffusion rate in bulk when 1-x⩽0.5, and by the concentration of oxygen vacancy when 1-x ⩾ 0.5. The stability of Sr0.5Bi0.5FeO3-δ was also investigated, and the high stability of it was attributed to the stable BO6 octahedra.
13 citations
01 Jul 2000
TL;DR: In this paper, the authors used LiLaNiO/gamma-Al2O3 as a catalyst for CH4-CO2-O2 reforming to syngas.
Abstract: CH4-CO2-O-2 reforming to syngas in a never Ba0.5Sr0.5Co0.8Fe0.2O3.delta oxygen-permeable membrane reactor using LiLaNiO/gamma-Al2O3 as catalyst was successfully reported. Excellent reaction performance was achieved with around 92% methane conversion efficiency, 95% CO2 conversion rate, and nearly 8.5mL/min.cm(2) oxygen permeation flux. In contrast to the oxygen permeation model with the presence of large concentration of CO2 (under such condition the oxygen permeation flux deteriorates with time), the oxygen permeation flux is really stable under the CH4CO2-O-2 reforming condition.
4 citations
TL;DR: In this article, B-site Bi-doped perovskites were exploited and synthesized for mixed conducting oxides, and cubic structures were formed for BaBi0.22O0.5O3-δ membranes at 875°C, which exhibited considerable high oxygen permeability at high temperature.
Abstract: Novel mixed conducting oxides, B-site Bi-doped perovskites were exploited and synthesized. Cubic perovskite structures were formed for BaBi0.2CoyFe0.8-yO3-δ (y⩽S0.4) and BaBixCo0.2Fe0.8-xO3-δ(x=0.1-0.5). The materials exhibited considerable high oxygen permeability at high temperature. The oxygen permeation flux of BaBi0.2Co0.35Fe0.45O3-δ membrane reached about 0.77×10-6 mol/cm2 · s under an air/helium oxygen partial pressure gradient at 900°C, which was much higher than that of other bismuth-contained mixed conducting membranes. The permeation fluxes of the materials increased with the increase of cobalt content, but no apparent simple relationship was found with the bismuth content. The materials also demonstrated excellent reversibility of oxygen adsorption and desorption. Stable time-related oxygen permeation fluxes were found for BaBi0.22O0.35Co0.35Fe0.45O33-δ and BaBi0.3Co0.2Fe0.5O3-δ membranes at 875°C.
2 citations