Production and Characterization of Carbon Molecular Sieves from Bituminous Lafia-Obi Nasarawa Coal by Pore Size Modification with Spent Engine Oil

Abstract

In this work, a carbon molecular sieve (CMS) was produced from a  bituminous Lafia-Obi Nasarawa coal. An initial activated carbon (AC) sample was prepared via chemical activation from the coal, from which the CMS samples were then produced through heat treatment processes and carbon deposition fromspent engine oil. Spent engine oil was pyrolyzed in order to deposit carbon at the pore mouth of coal-based AC to yield CMS. The effect of reaction temperature and holding time variation on the surface area, micropore pore volume and pore size of CMS was studied. Reaction  temperature was varied at 400, 550 and 700 °C while holding time was varied at 30 and 60 min. The Brunauer–Emmett–Teller (BET) method was used to calculate the surface areas, while the Dubinin–Radushkevich (DR) and Horváth-Kawazoe (HK) methods were used to determine the micropore
volumes and pore sizes of the AC and CMS, respectively. The CMS sample with the largest BET surface area (5.824 m2 g–1), DR micropore volume (0.172 cm3 g–1) and HK pore size (6.317 Å) were obtained at 700 °C reaction temperature and 60 min holding time. In addition to this, a molecular sieving ability test to separate benzene from a mixture of benzene and o-xylene in solution was carried out on the AC and CMS, with the CMS having a selective benzene percentage uptake of 61.36 %.

Keywords: Activated carbon (AC), carbon molecular sieves (CMS), carbon deposition, reaction temperature, holding time.