Highly Efficient NO Decomposition via Dual-Functional Catalytic Perovskite Hollow Fiber Membrane Reactor Coupled with Partial Oxidation of Methane at Medium-Low Temperature

Ion-Conducting Ceramic Membrane Reactors for the Conversion of Chemicals

Ion-conducting ceramic membranes, such as mixed oxygen ionic and electronic conducting (MIEC) membranes and mixed proton-electron conducting (MPEC) membranes, have the potential for absolute selectivity for specific gases at high temperatures. By utilizing these membranes in membrane reactors, it is possible to combine reaction and separation processes into one unit, leading to a reduction in by-product formation and enabling the use of thermal effects to achieve efficient and sustainable chemical production. As a result, membrane reactors show great promise in the production of various chemicals and fuels. This paper provides an overview of recent developments in dense ceramic catalytic membrane reactors and their potential for chemical production. This review covers different types of membrane reactors and their principles, advantages, disadvantages, and key issues. The paper also discusses the configuration and design of catalytic membrane reactors. Finally, the paper offers insights into the challenges of scaling up membrane reactors from experimental stages to practical applications.

Evaluation of Structural and Functional Properties of La0.6Sr0.4MnO3 Perovskite Prepared by the Fast Solution Combustion Approach

A series of La0.6Sr0.4MnO3 (LSM) perovskite was made using the rapid solution combustion method, which was calcined by varying the temperatures. In order to determine how the calcination temperature affected the nanopowders produced and calcined at various temperatures, their microstructural, morphological, compositional, optical, and electrical properties were analyzed using corresponding characterization tools. The XRD results showed the coexistence of the rhombohedral polymorphs R-3c and Pm-3m for the perovskite phase under a calcination temperature of 1400 °C, which were eliminated with increased calcination temperature. The average grain size was found to increase with increasing calcination temperature. The EDS analysis showed better agreement of the stoichiometry with the theoretical composition. The apparent porosity decreased with increasing temperature due to the coalescence of sintering pores. The sample obtained after calcination at 1500 °C showed 10.3% porosity. The hardness also improved with increasing calcination temperature and reached a maximum value of 0.4 GPa, which matched the bulk density. A similar trend was observed in the resistivity studies as a function of temperature, and all the samples exhibited a low resistivity of ~1.4 Ω·cm in the temperature range of 500–600 °C. The optical characterization showed broad absorption at 560–660 nm and bandwidth values between 3.70 and 3.95 eV, according to the applied heat treatment.

Direct Conversion of Methane to C2 Hydrocarbons in Solid-State Membrane Reactors at High Temperatures

Direct conversion of methane to C₂ compounds by oxidative and nonoxidative coupling reactions has been intensively studied in the past four decades; however, because these reactions have intrinsic severe thermodynamic constraints, they have not become viable industrially. Recently, with the increasing availability of inexpensive "green electrons" coming from renewable sources, electrochemical technologies are gaining momentum for reactions that have been challenging for more conventional catalysis. Using solid-state membranes to control the reacting species and separate products in a single step is a crucial advantage. Devices using ionic or mixed ionic-electronic conductors can be explored for methane coupling reactions with great potential to increase selectivity. Although these technologies are still in the early scaling stages, they offer a sustainable path for the utilization of methane and benefit from the advances in both solid oxide fuel cells and electrolyzers. This review identifies promising developments for solid-state methane conversion reactors by assessing multifunctional layers with microstructural control; combining solid electrolytes (proton and oxygen ion conductors) with active and selective electrodes/catalysts; applying more efficient reactor designs; understanding the reaction/degradation mechanisms; defining standards for performance evaluation; and carrying techno-economic analysis.

A Review on the Catalytic Decomposition of NO by Perovskite-Type Oxides

Direct catalytic decomposition of NO has the advantages of being a simple process, producing no secondary pollution, and being good for the economy, which has attracted extensive research in recent years. Perovskite-type mixed oxides, with an ABO3 or A2BO4 structure, are promising materials as catalysts for NO decomposition due to their low cost, high thermal stability, and, of course, their good catalytic performances. In this review, the influence factors, such as A-site substitution, B-site substitution and reaction conditions on the catalytic performance of catalysts have been expounded. The reaction mechanisms of direct NO decomposition are also discussed. Finally, major conclusions are drawn and some research challenges are highlighted.

Copper Phyllosilicates-Derived Catalysts in the Production of Alcohols from Hydrogenation of Carboxylates, Carboxylic Acids, Carbonates, Formyls, and CO2: A Review

Copper phyllosilicates-derived catalysts (CuPS-cats) have been intensively explored in the past two decades due to their promising activity in carbonyls hydrogenation. However, CuPS-cats have not been completely reviewed. This paper focuses on the aspects concerning CuPS-cats from synthesis methods, effects of preparation conditions, and dopant to catalytic applications of CuPS-cats. The applications of CuPS-cats include the hydrogenation of carboxylates, carboxylic acids, carbonates, formyls, and CO2 to their respective alcohols. Besides, important factors such as the Cu dispersion, Cu+ and Cu0 surface areas, particles size, interaction between Cu and supports and dopants, morphologies, and spatial effect on catalytic performance of CuPS-cats are discussed. The deactivation and remedial actions to improve the stability of CuPS-cats are summarized. It ends up with the challenges and prospective by using this type of catalyst.

NO direct decomposition: progress, challenges and opportunities

The progress in catalyst R&D, challenges, and opportunities for NO direct decomposition are summarized.

A mini-review on recent developments in SAPO-34 zeolite membranes and membrane reactors

Schematic diagram of a SAPO-34 membrane for various gas separation.

Catalytic mixed conducting ceramic membrane reactors for methane conversion

Schematic of catalytic mixed conducting ceramic membrane reactors for various reactions: (a) O₂ permeable ceramic membrane reactor; (b) H₂ permeable ceramic membrane reactor; (c) CO₂ permeable ceramic membrane reactor.