MOFs for use in adsorption heat pump processes

Thermally driven heat pumps can significantly help to minimize primary energy consumption and greenhouse gas emissions generated by industrial or domestic heating and cooling processes. This is achieved by using solar or waste heat as the operating energy rather than electricity or fossil fuels. One of the most promising technologies in this context is based on the evaporation and consecutive adsorption of coolant liquids, preferably water, under specific conditions. The efficiency of this process is first and foremost governed by the microporosity, hydrophilicity, and hydrothermal stability of the sorption material employed. Traditionally, inorganic porous substances like silica gel, aluminophosphates, or zeolites have been investigated for this purpose. However, metal-organic frameworks (MOFs) are emerging as the newest and by far the most capable class of microporous materials in terms of internal surface area and micropore volume as well as structural and chemical variability. With further exploration of hydrothermally stable MOFs, a large step forward in the field of sorption heat pumps is anticipated. In this work, an overview of the current investigations, developments, and possibilities of MOFs for use in heat pumps is given.