DEPOLYMERIZATION OF RIGID POLYURETHANE WASTE VIA CATALYTIC GLYCOLYSIS IN THE PRESENCE OF K, Na, AND Ca COMPOUNDS
DOI:
https://doi.org/10.15421/jchemtech.v34i1.349449Keywords:
polyurethane, depolymerization, catalysis, glycolysis, waste, recyclingAbstract
The process of chemical recycling of rigid polyurethane waste via catalytic glycolysis with diethylene glycol (DEG) was investigated. The purpose of this work was to study the influence of the nature of some alkaline earth compounds as homogeneous catalysts on the depolymerization of PU into a so-called recycled polyol with properties suitable for further application. The glycolysis process was carried out at a temperature of 220 °C for 40 min. with a mass ratio of polyurethane (PU) waste to DEG of 1 : 2.5. The K-, Na-, and Ca acetates and K carbonate, as homogeneous catalysts at constant mass concentrations (0.2 %, 0.4 %, and 0.6 %), were used. The effectiveness of depolymerization was evaluated by the physical and chemical properties of the obtained liquid products (i.e., recycled polyol), namely by hydroxyl-, acid-, and amine-number as well as by dynamic viscosity. It was found that the studied catalysts significantly intensify the depolymerization process compared to the non-catalytic reaction. Potassium carbonate at a concentration of 0.4 % allowed to obtain recycled polyol with a high hydroxyl number. The obtained results confirm the feasibility of K and Na acetates and carbonates for controlled depolymerization of solid PU waste.
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