Investigation of adsorption-enhanced reaction process of mercury removal from simulated natural gas by mathematical modeling

Hydroxyapatites modified with copper sulfide were studied as sorbents for mercury removal from gaseous streams containing low mercury concentration. A mathematical model was proposed to take into account adsorption, diffusion into the sorbent particle and chemical reaction inside the solid matrix. The chemical reaction mechanism for mercury fixation into the solid matrix is supported by XRD analysis results. The unknown parameters are estimated from experimental data by minimization of the unweighted least-squares function, using a hybrid of Newton-like and Particle Swarm Optimization methods. Results are shown for two hydroxyapatite sorbents developed in our lab. The model, with its optimized parameters, was used to study the dynamic behavior of a fixed bed adsorption process at different operational conditions. Simulation results show that the chemical fixation of mercury inside the solid matrix leads to an increase of mercury removal capacity and it provides insights about operational plant conditions.