Industrial Evaluation of Activated Navbahor and Nurota Bentonites as Locally Sourced Media for the Finishing Stage of Kerosene Demercaptanization

Abstract

This study evaluated activated bentonites from the Navbahor and Nurota deposits in Navoiy Province, Uzbekistan, as locally sourced media for the finishing stage of kerosene demercaptanization. The materials were assessed as alternatives to imported ATTA PULGUS clay in the clay-filter section of a MERICAT II fibre-film demercaptanization unit. The investigation comprised chemical characterisation, bulk-density measurement before and after thermal pretreatment, and assessment of fuel-quality parameters against OʻzDSt 1117:2007 using prescribed standard methods. Compared with the imported reference, activated Navbahor bentonite was silica–alumina dominated but contained less silica and alumina and more calcium, iron, and sulphate. Calcination at 500 °C for 6 h reduced the bulk density of Navbahor bentonite from 0.850 to 0.812 g/cm³ and that of Nurota bentonite from 0.940 to 0.890 g/cm³. In a 100 kg pilot loading, activated Navbahor bentonite improved Saybolt colour from +15 to +22 points, reduced specific electrical conductivity from 6 to 1 pS/m, and lowered mercaptan sulfur from 0.0018 to 0.001 wt.%, while copper-strip corrosion remained at Class 1. In the comparative industrial trial, kerosene treated with both activated local bentonites showed conductivity of 1 pS/m, mercaptan sulfur of 0.0017 wt.%, copper-strip corrosion of Class 1, and Saybolt colour of +15 points. The results indicate that activated Navbahor and Nurota bentonites provided technically acceptable polishing performance under the studied operating conditions.