Acceptor-doped, redox-active perovskite oxides such as La_0.8Sr_0.2FeO₃ (LSF) are active for ethane oxidation to CO_x but show poor selectivity to ethylene. This article reports molten Li₂CO₃ as an effective “promoter” to modify LSF for chemical looping–oxidative dehydrogenation (CL-ODH) of ethane. Under the working state, the redox catalyst is composed of a molten Li₂CO₃ layer covering the solid LSF substrate. The molten layer facilitates the transport of active peroxide (O₂²⁻) species formed on LSF while blocking the nonselective sites. Spectroscopy measurements and density functional theory calculations indicate that Fe⁴⁺→Fe³⁺ transition is responsible for the peroxide formation, which results in both exothermic ODH and air reoxidation steps. With >90% ethylene selectivity, up to 59% ethylene yield, and favorable heat of reactions, the core-shell redox catalyst has an excellent potential to be effective for intensified ethane conversion. The mechanistic findings also provide a generalized approach for designing CL-ODH redox catalysts.

The oxidative coupling of methane to higher hydrocarbons offers a promising autothermal approach for direct methane conversion, but its progress has been hindered by yield limitations, high temperature requirements, and performance penalties at practical methane partial pressures (~1 atm). In this study, we report a class of Li₂CO₃-coated mixed rare earth oxides as highly effective redox catalysts for oxidative coupling of methane under a chemical looping scheme. This catalyst achieves a single-pass C₂₊ yield up to 30.6%, demonstrating stable performance at 700 °C and methane partial pressures up to 1.4 atm. In-situ characterizations and quantum chemistry calculations provide insights into the distinct roles of the mixed oxide core and Li₂CO₃ shell, as well as the interplay between the Pr oxidation state and active peroxide formation upon Li₂CO₃ coating. Furthermore, we establish a generalized correlation between Pr⁴⁺ content in the mixed lanthanide oxide and hydrocarbons yield, offering a valuable optimization strategy for this class of oxidative coupling of methane redox catalysts.

Oxidative dehydrogenation (ODH) of n -butane has the potential to efficiently produce butadiene without equilibrium limitation or coke formation. Despite extensive research efforts, single-pass butadiene yields are limited to <23% in conventional catalytic ODH with gaseous O ₂ . This article reports molten LiBr as an effective promoter to modify a redox-active perovskite oxide, i.e., La _0.8 Sr _0.2 FeO ₃ (LSF), for chemical looping–oxidative dehydrogenation of n -butane (CL-ODHB). Under the working state, the redox catalyst is composed of a molten LiBr layer covering the solid LSF substrate. Characterizations and ab initio molecular dynamics (AIMD) simulations indicate that peroxide species formed on LSF react with molten LiBr to form active atomic Br, which act as reaction intermediates for C─H bond activation. Meanwhile, molten LiBr layer inhibits unselective CO ₂ formation, leading to 42.5% butadiene yield. The redox catalyst design strategy can be extended to CL-ODH of other light alkanes such as iso -butane conversion to iso -butylene, providing a generalized approach for olefin production.

Compared to the Claus process, selective H₂S catalytic oxidation to sulfur is a promising reaction, as it is not subject to thermodynamic limitations and could theoretically achieve ~100% H₂S conversion to sulfur. In this study, we investigated the effects of Co and Fe co-doping in ABO₃ perovskite on H₂S selective catalytic oxidation. A series of LaFe_xCo_1−xO₃ (x = 0, 0.2, 0.4, 0.6, 0.8, 1.0) perovskites were synthesized by the sol-gel method. Compared to LaFeO₃ and LaCoO₃, co-doped LaFe_xCo_1−xO₃ significantly improved the H₂S conversion and sulfur selectivity at a lower reaction temperature. Nearly 100% sulfur yield was achieved on LaFe_0.4Co_0.6O₃ under 220 °C with exceptional catalyst stability (above 95% sulfur yield after 77 h). The catalysts were characterized by XRD, BET, FTIR, XPS, and H₂-TPR. The characterization results showed that the structure of LaFe_xCo_1−xO₃ changed from the rhombic phase of LaCoO₃ to the cubic phase of LaFeO₃ with Fe substitution. Doping with appropriate iron (x = 0.4) facilitates the reduction of Co ions in the catalyst, thereby promoting the H₂S selective oxidation. This study demonstrates a promising approach for low-temperature H₂S combustion with ~100% sulfur yield.

CO ₂ is reduced to methanol via the synergistic effect of expansion of the interlayer spacing and sulfur vacancies of MoS ₂ .