Application of carbon nanotubes prepared from CH4/CO2 over Ni/MgO catalysts in CO2 capture using a BEA–AMP bi-solvent blend

Abstract

Abstract Carbon nanotubes (CNTs) were synthesized by the chemical vapour deposition of methane and carbon dioxide over a Ni/MgO catalyst. The synthesized CNTs were then mixed with K/MgO catalyst at different ratios and used as the catalyst for CO2 absorption in butylethanolamine-2-amino-2-methyl-l-propanol bi-solvent blend. The catalysts were characterized using X-ray diffraction, scanning electron microscopy, butylethanolamine, thermal gravimetric analysis and temperature-programmed desorption of carbon dioxide in order to determine the characteristics responsible for good CO2-absorption performance. The results showed that, with the addition of a catalyst into the amine solution, the amine reached equilibrium CO2 loading faster than without a catalyst. Also, the increase in the CNT content of the KMgO/CNTs catalyst made the CO2 absorption reach equilibrium much more quickly compared with just KMgO alone and without a catalyst. The KMgO/CNTs at a ratio of 1:4 yielded the fastest time to reach CO2-loading equilibrium at 240 min, which was mainly due to the increase in strong basic sites as well as the highest total basic sites with an increase in CNT content. In addition, because of the extremely large specific surface area and pore volume generated due to the CNT, the number of exposed active centres per unit mass increased tremendously, leading to a corresponding tremendous increase in CO2 absorption.