Equilibrium steps for adsorption of nitrogen compounds : examining the potential of silica application as adsorbent

Abstract

The hydrotreating (HDT) process currently used to reduce the sulphur content in fuels requires high energy consumption and hydrogen. Furthermore, the presence of nitrogen compounds makes them more severe. This work studies the removal of nitrogen compounds present in a sample of heavy diesel using a commercial silica sample. Adsorption tests were performed in a stirring bath to generate the equilibrium data. Three test conditions were used at temperatures of 40, 80 and 100 °C. In adsorption studies in a fixed bed, the influence of temperature and liquid hourly space velocity (LHSV) was observed . In the regeneration test of the adsorbent, adsorption was achieved at 80 °C and desorption at 60 °C. Ethanol was used as the solvent and fourteen adsorption tests and thirteen desorption tests were performed. The removal of sulphur compounds in the stirring bath tests were checked. From a comparative perspective, the silica adsorbent used showed a higher affinity to the removal of nitrogen compounds than those related to sulphur in the stirring bath tests. The recovery test showed a reduction of approximately 20% in adsorption capacity of the adsorbent treated after the adsorption cycle in relation to the fresh adsorbent. This result indicates that the silica sample can be reused.