In the current global energy context, alternatives to natural gas of fossil origin, in particular biogas, are highly coveted. Like methane of fossil origin, these bio-resources, generated by the methanation of organic waste, must be purified to obtain a gas that can be used in domestic or industrial installations. This purification step, which aims in particular to extract as selectively as possible contaminants such as carbon dioxide or hydrogen sulphide naturally present in methane, represents a significant economic and energy cost in the exploitation of this source of energy. . It operates on an industrial scale using in particular polymer membranes which are more or less selective.
As part of a collaboration with Saudi Arabia and China, chemists from the Charles Gerardt Montpellier Institute (CNRS/Ecole Nationale Supérieure de Chimie de Montpellier/Montpellier University) have just described in Science a completely new family of hybrid MOF/polymer membranes capable of separating carbon dioxide and hydrogen sulphide from methane with unparalleled selectivity, permeability and ease of processing. Their feat consists in dispersing MOFs presenting perfectly aligned microporous channels in the form of nano-layers in an already commercial polymer membrane. These MOFS create continuous, highly selective gas paths that achieve exceptional separations of carbon dioxide and hydrogen sulfide from methane under real-world operating conditions. Applicable to other gas mixtures, these new membranes might well revolutionize molecular purification, one of the major challenges in the field of energy and the environment (air purification, hydrogen purification, etc.)
*Metal-organic frameworks networks (MOFs) are hybrid materials (inorganic and organic) “cages or channels” with exceptional porosity which make it possible to store and/or separate large quantities of gases such as CO2or to act as a nano-catalyst to accelerate certain chemical reactions.
