Novel materials for utilization of natural gas and hydrogen

Separation of gas molecules is one of the most important areas in production of fuels, chemicals and many other industries. Normally the overall cost of the final gas or chemical is impacted in more than 30% by the cost of separation, so improving the separation stages will have a final impact in the cost of products. There are diverse techniques that can be used for separation of gas molecules. Adsorption of targeted molecules on specific surfaces is one of them: even our body is able to selectively adsorb oxygen from air every time we breathe. The secret for a good and efficient separation is to have the right material and a right way of using it (our brain is telling the lungs to breathe faster or deeper when we need more oxygen). So a good collaboration between material developers and process engineers is necessary. This project has dealt with all the development stages of a new class of porous materials, metal-organic frameworks (MOFs). These materials are known by having an enormous surface area (in one gram of MOF you can have more area than in the field of Ullevål Stadium). Previous collaboration between SINTEF and UiO resulted in the development of a MOF family of material CPO, abbreviating Coordination Polymer Oslo. The most well-known of this family is CPO-27 which is actually among the most cited materials in scientific literature and when is synthesized with magnesium, is in the top-five of porous material with the higher ability to retain CO2 among all the porous solids discovered so far. In the current project, the work of UiO was mostly oriented to increase the family of CPO MOF materials. They have reported four new structures (CPO-58, CPO-59, CPO-71 and CPO-72). Some of these materials present interest properties that needed to be further tested to fully explore their capabilities in the separation processes. In order to realize the potential of MOF materials, we have tested the potential of several of these porous structures for gas separation. This role was taken by SINTEF Materials and Chemistry. Another MOF developed in Norway and very well recognized in literature is the UiO family. In this project, we have tested different members of the UiO family to separate carbon dioxide from natural gas. Indeed, one of the materials has shown some interest properties in this field (UiO-67) and will be further explored in the near future. Another MOF material (UTSA-16) was also tested for the possibility of removing contaminants normally found in hydrogen production. The material has shown very good properties for this application, able to perform better than existing materials (activated carbon and zeolites). When a MOF is made, is in powder form. To be used in separation processes, particles bigger than powder are required and thus the MOF material has to be shaped. All the technology developed to form ceramic materials involves the utilization of extensive amount of heat that will severely damage or destroy the MOFs. For this reason, new technology for shaping these materials is required and this has been one of the main limitations to commercialization of MOF materials. Within this project we have successfully prepared more than 150 grams of shaped (extruded) UTSA-16 material able to keep the adsorption properties. This work was published in 2014 and to date is the only work dealing with MOF extrusion resulting in surface area reduction of less than 10% reported in literature.

Metal-organic frameworks, also known as coordination polymers, have eminently promising properties regarding application as gas storage systems, sensors, magnetic materials, in ion exchange or catalysis. Recent results indicate that microporous metal-orga nic frameworks can be highly selective in which type of gas they adsorb, a property which will be highly useful to exploit in gas separation technology. The principal objective of this project is to develop MOF materials with favorable properties in stora ge and separation of natural gas (e.g. methane) and the components of synthesis gas, specifically hydrogen, and carbon monoxide. Hydrogen produced from synthesis gas is a typical source used in fuel cell technology, and the remaining CO must be removed to prevent poisoning of the fuel cell' catalyst. Natural gas is a cleaner fuel than currently used gasoline, but storage and purification processes must be developed. MOFs can be used to store large amounts of methane per volume and purify these. MOFs with catalytic ability towards natural gas or its follow up products are structurally related to those used in separation, and they will also be explored in the project.