Novel molten phase route for composite CO2 separation membranes

Advances in Ceramic-Carbonate Dual-Phase Membrane Reactors for Direct CO2 Separation and Utilization

Excessive (carbon dioxide) CO2 emissions are a primary factor contributing to climate change. As one of the crucial technologies for alleviating CO2 emissions, carbon capture and utilization (CCU) technology has attracted considerable global attention. Technologies for capturing CO2 in extreme circumstances are indispensable for regulating CO2 levels in industrial processes. The unique separation characteristics of the ceramic-carbonate dual-phase (CCDP) membranes are increasingly employed for CO2 separation at high temperatures due to their outstanding chemical, thermal durability, and mechanical strength. This paper presents an overview of CO2 capture approaches and materials. It also elaborates on the research progress of three types of CCDP membranes with distinct permeation mechanisms, concentrating on their principles, materials, and structures. Additionally, several typical membrane reactors, such as the dry reforming of methane (DRM) and reverse water-gas shift (RWGS), are discussed to demonstrate how captured CO2 can function as a soft oxidant, converting feedstocks into valuable products through oxidation pathways designed within a single reactor. Finally, the future challenges and prospects of high-temperature CCDP membrane technologies and their related reactors are proposed.

Metallic sealants increase flux and change selectivity in supported molten-salt membranes

Metallic sealants are widely used with high-temperature membranes. Here we show that their use in supported molten-salt membranes results in order-of-magnitude differences in CO2 flux and introduces O2 co-permeation. The 'short-circuiting' effect they introduce has important implications for the design of future experiments, and the interpretation of past work.

Design and Validation of an Experimental Setup for Evaluation of Gas Permeation in Ceramic Membranes

An experimental setup for the evaluation of permeation of gaseous species with the possibility of simultaneously collecting electrochemical impedance spectroscopy data in disk-shaped ceramic membranes was designed and assembled. It consists of an alumina sample holder with thermocouple tips and platinum electrodes located close to both sides of the sample. Water-cooled inlet and outlet gas connections allowed for the insertion of the sample chamber into a programmable split tubular furnace. Gas permeation through a ceramic membrane can be monitored with mass flow controllers, a mass spectrometer, and an electrochemical impedance analyzer. For testing and data validation, ceramic composite membranes were prepared with the infiltration of molten eutectic compositions of alkali salts (lithium, sodium, and potassium carbonates) into porous gadolinia-doped ceria. Values of the alkali salt melting points and the permeation rates of carbon dioxide, in agreement with reported data, were successfully collected.

CO2/CH4 Separation via Carbon-Based Membrane: The Dynamic Role of Gas-Membrane Interface

Membrane separation is considered one of the most promising CO₂/CH₄ separation technologies currently available because it is a safe, environment-friendly, and economical method. However, the inability of membrane materials to reconcile the trade-off between permeability and permeation selectivity limits their further applications; moreover, the mechanism underlying this process is unclear, which is mainly determined by the performance of gas adsorption and diffusion. Therefore, this paper describes the effect of gas adsorption and diffusion on membrane separation by assessing the fundamental gas-membrane and gas-gas interactions. Combining molecular simulation methods (Monte Carlo and molecular dynamics simulation) and a thermodynamic model called "linearized nonequilibrium thermodynamic transfer model", we investigate the permeability and permeation selectivity for CO₂/CH₄ in five carbon-based membranes and propose a general method for screening membrane materials. The interaction-dominated mechanism derived in this work provides new insights into membrane separation and facilitates the screening of high-performance membrane materials.