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This study proposes a new dense membrane for selectively separating CO2 and O2 at high temperatures and simultaneously producing syngas. The membrane consists of a cermet-type material infiltrated with a ternary carbonate phase. Initially, the co-doped ceria of composition Ce0.9Zr0.05Y0.05O2−δ (CZY) was synthesized by using the conventional solid-state reaction method. Then, the ceramic was mixed with commercial silver powders using a ball milling process and subsequently uniaxially pressed and sintered to form the disk-shaped cermet. The dense membrane was finally formed via the infiltration of molten salts into the porous cermet supports. At high temperatures (700–850 °C), the membranes exhibit CO2/N2 and O2/N2 permselectivity and a high permeation flux under different CO2 concentrations in the feed and sweeping gas flow rates. The observed permeation properties make its use viable for CO2 valorization via the oxy-CO2 reforming of methane, wherein both CO2 and O2 permeated gases were effectively utilized to produce hydrogen-rich syngas (H2 + CO) through a catalytic membrane reactor arrangement at different temperatures ranging from 700 to 850 °C. The effect of the ceramic filler in the cermet is discussed, and continuous permeation testing, up to 115 h, demonstrated the membrane's superior chemical and thermal stability by confirming the absence of any chemical interaction between the material and the carbonates as well as the absence of significant sintering concerns with the pure silver. [ABSTRACT FROM AUTHOR]

Li2CuO2 and different iron-containing Li2CuO2 samples were synthesized by solid state reaction. On iron-containing samples, atomic sites of copper are substituted by iron ions in the lattice (XRD and Rietveld analyses). Iron addition induces copper release from Li2CuO2, which produce cationic vacancies and CuO, due to copper (Cu2+) and iron (Fe3+) valence differences. Two different physicochemical conditions were used for analyzing CO2 capture on these samples; (i) high temperature and (ii) low temperature in presence of water vapor. At high temperatures, iron addition increased CO2 chemisorption, due to structural and chemical variations on Li2CuO2. Kinetic analysis performed by first order reaction and Eyring models evidenced that iron addition on Li2CuO2 induced a faster CO2 chemisorption but a higher thermal dependence. Conversely, CO2 chemisorption at low temperature in water vapor presence practically did not vary by iron addition, although hydration and hydroxylation processes were enhanced. Moreover, under these physicochemical conditions the whole sorption process became slower on iron-containing samples, due to metal oxides presence. [ABSTRACT FROM AUTHOR]

To be considered a good CO2 capture material for industrial applications, alkaline ceramics have to present several properties such as fast sorption and desorption kinetics, large sorption capacities, regenerability and stability, and a wide operating temperature range. In this sense, Li4SiO4 fulfills some of these features, although it has some kinetic disadvantages at temperatures lower than 500 °C and under low CO2 partial pressures. Herein, we show an easy an efficient way to synthesize a Fe-containing Li4SiO4 solid solution (Li4+xSi1−xFexO4, with x≤ 0.5); by a dry ball milling synthesis, with high CO2 capture capacities. A synergic effect, between the microstructural features given by the proposed synthesis method and the iron content, improves the CO2 capture exhibited by the material in different ways: (1) Li4+xSi1−xFexO4 solid solution samples are able to trap large amounts of CO2 between 200 and 650 °C. At 200 °C, the solid solution chemisorbs 11 wt% of CO2, the largest amount of CO2 captured reported so far in the literature at this temperature; (2) iron containing samples diminish the CO2 capture dependence on temperature; (3) CO2 capture was considerably improved under low partial pressures of CO2 and (4) iron redox properties enhanced the CO2 capture, by using a low partial pressure of O2. [ABSTRACT FROM AUTHOR]

A synergetic system for the coupled CO oxidation and CO2 trapping was proposed and studied in the present work by using a ceria-based material and CaO as catalyst and absorbent, respectively. Specifically, Ce0.8Sm0.15Sr0.05O2 (CSSO) was synthesized by the EDTA--citrate complexing method and the resultant powders were characterized by XRD, SEM, and N2adsorption--desorption measurements. The structure was identified as a fluorite phase, and the BET analysis showed specific areas of 25.6 and 2.6 m²/g for the samples heat-treated at 650 and 1000 °C, respectively. Dynamic thermogravimetric analyses performed under CO2, CO, CO-O2, and O2 containing atmospheres showed the thermal stability and reactivity of the ceria-based catalyst. Then, the CO oxidation tests were evaluated in two stages: first, the dynamic and isothermal analyses for the CO oxidation by the CSSO treated at 650 and 1000 °C; then, the evaluation of the CO oxidation properties of the proposed catalyst with in situ CO2 capture by adding CaO to the system. The results for the CSSO1000--CaO system evidenced simultaneous double process produced by the synergetic CO oxidation at temperatures between 350 and 650 °C and the CO2 chemisorption on the CaO. Furthermore, the combined materials reduce the different temperature processes probably due to the CaO partial catalytic activity. [ABSTRACT FROM AUTHOR]

Layered double perovskites have the potential to further expand the vast space of optoelectronic properties and applications of halide perovskites. Among the ∼60 known members, to date only the ⟨111⟩-oriented layered double perovskites, Cs 4 Cd 1- x Mn x Bi 2 Cl 12 , have shown efficient photoluminescence (PL). The replacement of Bi with Sb in these materials was investigated, resulting in two new families of layered inorganic perovskite alloys with full solubility. The first, Cs 4 Cd 1- x Mn x Sb 2 Cl 12 , exhibits a PL emission at 605 nm ascribed to Mn 2+ centers, with a maximum quantum yield of 28.5%. The second, Cs 4 Cd 0.8 Mn 0.2 (Sb 1- y Bi y ) 2 Cl 12 , contains a fixed amount of Mn 2+ and Cd 2+ but variable Sb 3+ and Bi 3+ concentrations. We observed a decreased efficiency of the Cs 4 Cd 1- x Mn x Sb 2 Cl 12 family compared to that of Cs 4 Cd 1- x Mn x Bi 2 Cl 12 , which was attributed to a decreased spin-orbit and Jahn-Teller couplings in Sb and the subsequent increased electronic delocalization. The present work lays out a roadmap to achieve high photoluminescence efficiencies in layered double perovskites.