Optimization of the Neutralization Process for Cesium Catalyst Removal after Polyol Production

Abstract

The aim of this study was the optimization of the neutralization process to remove the catalyst cesium hydroxide from crude polyether polyols. Sulfuric acid was chosen as the neutralization agent. First of all, the water content in the neutralization agent solution was optimized. An optimum particle size was obtained for water content between 2 and 3 wt %, and even the cesium content fell within the specifications. Higher water contents cause the solubilization of the cesium sulfate crystals. An increase in the temperature decreased the cesium sulfate particle size, not being retained by the filter and increasing the final polyol cesium content. Acidity was not within specifications whatever the temperature, varying between 0.18 and 0.22 mg of KOH/g. To obtain both parameters (cesium content and acidity) within specification, temperature and time of the dehydration step were modified. An excess of H2SO4 allowed us to obtain a suitable particle size for filtration; however, the acidity value was out of specification, suggesting the necessity to find a new process to remove the catalyst in the polyether polyol production.