Molecular Dynamics Simulation of the Interactions Between Carbon Dioxide and a Natural-based Carbonaceous Microporous Material

Abstract

Oil palm plantation has drastically changed the scenario of Malaysian agriculture and economy since the second half of the 20th century. World palm oil production in 1980 was around 5.0 million tonnes, doubled to 11.0 million tonnes in 1990, reaching at the beginning of the 21^th century approximatively 21.8 million tonnes per year. Malaysia is responsible of about half of the world palm oil production (10.8 million tonnes), thus becoming the world’s largest producer and exporter of palm oil. Oil palm industries also generate large amounts of lignocellulosic biomass waste as a sub-product, which currently has no economic market value other than feedstock for energy valorisation in some limited cases. The utilization and reformulation of this biomass as new materials with added value, would reduce accumulation of waste, mitigating the environmental impact of such intensive industry sector, and would simultaneously generate further economic revenue. In this work, we have studied the interactions of CO₂/N₂ streams with one slit-like graphite layers, using Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) molecular dynamics simulations, to simulate new carbon-based adsorbents from empty fruit bunches (EFB). Simulations were conducted using the high-performance computing (HPC) service provided by the University of Aberdeen (Scotland, UK), following accuracy tests to yield minimum operational costs. The simulations provided density profiles of CO₂ and N₂ molecules as a function of temperature (300/400/500 K), pressure (1/5/10 atm) and micro-meso porosity (12/20/30 Å). The results showed that the number of CO₂ molecules retained in the graphite framework decreases at higher temperatures and lower pressures, in accordance with the exothermicity of the process, and smaller pore sizes promote CO₂ adsorption at the tested pressures, due to the superposition of the Van der Waals force given by two adjacent walls of slit pores. Our findings exhibit the potential of lignocellusic materials from palm oil tree as materials for CO₂ capture.