Impacts of Calcination Temperature on Preparation of a Solid Acid Catalyst by Sulfonation of Single-Walled Carbon Nanohorns Dispersed with Iron Nanoparticles

Abstract

The present study investigates a solid acid catalyst synthesized using single walled-carbon nanohorns dispersed with Fe nanoparticles. It was found that this catalyst exhibited a high acid site concentration of 3.6 mmol/g, which was about twice that of the largest record of nanotube-based solid acid catalyst. A two-step process was employed in the catalyst preparation, comprising an acid impregnation step using sulfuric acid, followed by a calcination step in air was performed. This work focused on investigating the in uence of the temperature in the calcination step, which could affect the morphology, the activity, and the magnetic property of the catalyst. X-Ray di raction analysis suggested that the catalysts prepared here with the high acid site concentration included nanoparticles of Fe and Fe 3 O 4 because the Fe nanoparticles in the catalyst could be partially oxidized in the calcination step, while the carbonaceous part of the catalyst became porous to increase the speci c surface area. Although this oxidation caused an obvious reduction in the magnetic susceptibility of the catalyst, the catalyst was able to be magnetically recovered. It was found that the above mentioned high acid site concentration could be achieved by employing the optimum calcination temperature (400°C).