Synthesis Gas Production from Methane with SrFeCo_0.5O_y Membrane Reactor

Abstract

Partial oxidation of methane to synthesis gas was investigated in a reactor consisting of an oxygen-permeable SrFeCo 0.5 O y membrane tube and a Ni/γ-Al 2 O 3 catalyst bed located after the membrane tube. In this reactor, part of methane reacted with oxygen that permeated through the membrane from air, and the resultants (H 2 O, CO 2 ) and the rest of methane were transported to the catalyst bed where they were converted to syngas. When a reactor of membrane surface area 4.6 cm 2 was run at 900 °C with a methane feeding rate of 26.8 mL/min, the throughput conversion of methane was ∼98%, the CO selectivity ∼98%, H 2 /CO ∼1.8, syngas generation rate 16 mL/min/cm 2 . Under the reactor conditions, the layered phase Sr 4 (Fe,Co) 6 O 13 in the membrane gradually decomposed to a perovskite phase SrFe 1-x Co x O 3-δ with high oxygen permeability and spinel phase [(CoFe)] 2 CoO 4 with catalytic activity toward the oxidation of methane. The Ni-based reforming catalyst exhibited desirable activity and stability in the membrane reactor, which may be attributed to the absence of the "hot spots" in the catalyst.

Mixed-conducting oxygen permeable ceramic membranes for the carbon dioxide reforming of methane

“…In all reaction tests, the CH 4 : CO 2 ratio was 1 : 1 and the CH 4 and CO 2 comprised 80% of the feed. During the SFC membrane experiments, the remaining 20% of the feed was pure argon while specific percentages of O 2 in Ar were used for experiments with the stainless steel blank membrane.…”

“…[1][2][3][4] Because of the high economic, environmental, and safety costs associated with pure oxygen, oxygen-permeable ceramic membranes have been explored as an alternative oxygen source for hydrocarbon conversion reactors. [1][2][3][4][5][6][7][8][9][10] These non-porous ceramic materials allow the conduction of oxygen ions through the lattice of the solid material resulting in a 100% selectivity for oxygen regardless of the source gas. The mixed-conducting materials of interest for membrane reactor applications conduct electrons as well as oxygen ions, so they require only high temperature (typically 700 uC or higher) and an imposed oxygen potential gradient to transmit oxygen.…”

Chemical expansion of La0.8Sr0.2Fe0.7Ga0.3O3–δ

“…Such type of membranes could replace Air Separation Unit (ASU) for production of oxygen in the Partial Oxidation of Methane (POM) to syngas (H 2 /CO) process. Energy-savings are expected compare to ASU based process [1,2,3]. The semi-permeability of oxygen through MIECs occurs at high temperature (873 -1173 K) under a gradient of chemical potential between oxidizing and reducing side.…”

“…Oxygen diffusion is possible due to the presence of oxygen vacancies (Schottky defects) and electron holes. Mixed conducting oxides having a ABO 3 δ , referred to as LSFG later in the text. This material presents a good compromise between oxygen permeation fluxes and mechanical stability [4,5,6].…”

Evidence for oxygen vacancy manipulation in La1/3Sr2/3FeO3−𝜹 thin films via voltage controlled solid-state ionic gating

“…These redox effects have traditionally attracted interest in the solid oxide fuel cell (SOFC) and oxygen permeable membrane communities, where the temperatures of operation are typically well beyond the temperature range of traditional electronic devices. 13,14 In thin films, manipulation of oxygen vacancy concentrations can occur at lower temperatures due to the reduced material volume, the greater importance of surface effects as the material thickness is reduced, and the increased electric field magnitude associated with a given bias applied over nanoscale dimensions. 15,16 Recent work examining the chemical expansion in La 1-x Sr x CoO 3 films has demonstrated reversible bias-induced oxygen manipulation at 200 • C, inducing chemical strains up to 2.7% with an applied bias of 400 V. 17 This voltage-induced response was found to be similar to annealing the films under flowing oxygen, indicating that oxygen stoichiometry can be manipulated in multiple ways with external fields without damaging the overall crystal structure.…”