Review of proton conductors for hydrogen separation

Abstract

There is a global push to develop a range of hydrogen technologies for timely adoption of the hydrogen economy. This is critical in view of the depleting oil reserves and looming transport fuel shortage, global warming, and increasing pollution. Molecular hydrogen (H 2 ) can be generated by a number of renewable and fossil-fuel-based resources. However, given the high cost of H 2 generation by renewable energy at this stage, fossil or carbon fuels are likely to meet the short-to medium-term demand for hydrogen. In view of this, effective technologies are required for the separation of H 2 from a gas feed (by-products of coal or bio-mass gasification plants, or gases from fossil fuel partial oxidation or reforming) consisting mainly of H 2 and CO 2 with small quantities of other gases such as CH 4 , CO, H 2 O, and traces of sulphur compounds. Several technologies are under development for hydrogen separation. One such technology is based on ion transport membranes, which conduct protons or both protons and electrons. Although these materials have been considered for other applications, such as gas sensors, fuel cells and water electrolysis, the interest in their use as gas separation membranes has developed only recently. In this paper, various classes of proton-conducting materials have been reviewed with specific emphasis on their potential use as H 2 separation membranes in the industrial processes of coal gasification, natural gas reforming, methanol reforming and the watergas shift (WGS) reaction. Key material requirements for their use in these applications have been discussed.

Properties and applications of perovskite proton conductors

“…In general, a high temperature in the range from 800 to 950 °C [28] is necessary for an appropriate conversion of the natural gas in H 2 . The study of ceramic membranes of perovskite structure has received great attention, mainly due to the possibility of reducing that temperature regime (500-700 °C) and also due to the low cost in relation to the commonly used palladium membranes 29 . Other great advantage in using the protonic conductor membranes such as barium zirconate is the possibility to perform, in the same electrochemical device, both processes of reforming and gas separation, simultaneously.…”

Review—Solid Electrolytes in Rechargeable Electrochemical Cells

“…Those with a low melting temperature T m and/or glass-transition temperature T g can be molded to a desired shape, even to providing a contact to the entire surface area of smallparticle cathodes, which can allow an all-solid-state battery provided the volume change of the cathode particles on cycling is small ( V ≤ 1%). The ionic conductivities of glasses have been studied since the early 1970s; sulfides [22][23][24] 26 however, they lose their water of crystallization under conditions of low humidity and partially under the pressure of pelletization. 27 Sossina Haile 28,29 has investigated crystalline water-soluble acids such as CsHSO 4 and CsH 2 PO 4 as low-temperature hydrogen-air fuel-cell electrolytes; the cells operate in water vapor in the narrow temperature interval 150-250…”

Optimizing the Manufacturing Method of Half-Cell Fuel Cell Based on Solid Electrolyte with Hydrogen Ion Conductivity

“…A proposed solution that is taken by the result of extensive research of a group of researchers including Badwal, is using mixed solid solutions of perovskite structures to achieve a compromise between the properties of both materials [13]. Since both compounds, barium zirconate and barium cerate, are soluble in any proportion, replacement of appropriate amount of Zr into barium cerate could make a compound with suitable chemical stability and high proton conductivity.…”