Mercury removal from heavy naphtha by various adsorbents

Abstract

Previous research has shown the feasibility of using Beta zeolite for mercury removal from n-heptane (90% and 15% adsorption were achieved for diphenyl mercury and metallic mercury, respectively). In this work, the adsorption capacity for metallic mercury (Hg) on Beta zeolite impregnated with copper sulfide was studied in an attempt to increase the adsorption efficiency for a removal of metallic mercury. For comparison, various adsorbents - alumina (Al2O3), Beta zeolite (BEA), activated carbon (AC), CuS on alumina, CuS on Beta zeolite, and CMG273 - were tested. Heavy naphtha spiked with metallic mercury was used for kinetics of adsorption and adsorption isotherm studies in a batch system at 50C. The results from kinetics studies showed that for unimpregnated adsorbents, the adsorption efficiencies were low. The significant improvement was observed on CuS impregnated adsorbents. The adsorption kinetics followed the pseudo second order rate expression and the equilibrium data fitted reasonably well to Langmuir isotherm. All the adsorption parameters derived from the experimental data reflect the feasibility of metallic mercury removal by using CuS adsorbents. The breakthrough curves from a continuous system showed that CuS/BEA exhibited longer breakthrough time and shorter mass transfer zone than CuS/Al2O3.