Life-cycle assessment as a tool for eco-design of metal-organic frameworks (MOFs)

Metal-organic framework (MOF) materials are porous materials with high surface area that offer enormous flexibility of design and tailoring of its surface properties to be used in diverse chemical processes. Most of the reported properties of MOF materials were evaluated in powder materials produced in small scale where the synthesis has been optimized to obtain crystalline powders. Ideally, the industrialization of these materials will also be associated to efficient scalable synthesis protocols. Moreover, for these materials to be used as environmental-benign materials, their synthesis has to be sustainable. We present a cradle-to-gate life-cycle assessment of four different synthesis protocols to produce a MOF material (CPO-27-Ni also termed as MOF-74 and DOBDC) which is one suitable novel adsorbent material for carbon capture and storage (CCS) technologies. We have demonstrated that using a LCA is possible to idealize a methodology for eco-design of MOF materials. With our analysis we have determined that the impact of using solvents in the synthesis is considerable. Moreover, surprisingly, the LCA analysis helped us identifying that the utilization of solvents for the cleaning and purification steps has an equally (or even larger) impact in the environmental indicators. Utilization of solvents should be avoided if possible or reutilization strategies should be envisaged if is not possible to eliminate them.