Cleaner production of polyurethane (PU) foams through use of hydrodesulfurization (HDS) spent catalyst.

Due to the increased population in the urbanized areas, considerable attention is being paid on the development of energy-efficient buildings. In construction, the use of insulating foams has grabbed considerable attention in recent decades due to their porous structure that can reduce thermo-acoustic conductivity leading to higher energy efficiency. Nonetheless, the production of certain foams (e.g., polymer foams) is based on harmful chemical substances, such as isocyanate, as well as having difficulty being recycled. In this regard, this study adopted the use of hydrodesulfurization (HDS) spent catalyst, which is a byproduct of petroleum industry and is known to be a hazardous solid waste material, to produce a more environmentally friendly composite foam with lower thermal conductivity. In this sense, a series of material property tests, as well as thermal conductivity test, have been conducted. In addition, to further confirm the impact of HDS inclusion in the produced foams, energy cost savings and CO 2 emission reduction based on their actual application in four different environments and four different fuel types for heating have been evaluated. The results are found to be highly promising and point to the great potential of utilizing HDS spent catalyst as a hazardous waste to enhance the efficiency of foams leading to CO 2 emission and energy use reduction by up to 68.79 kg/m 2 and 8.6 kWh/m 2 , respectively. Finally, this would reduce the heating cost, up to 0.69 $/m 2  in an idealized building. In the end, suggestions for future studies in this area are also provided.