Syngas to Green Fuel Conversion: Nanocatalysis Approach

Abstract

Pretreating a carbon nanotube (CNT) support by refluxing it in 35 vol % nitric acid and then heating it at temperatures of 600–900 °C was found to result in the formation of defects on the CNTs. Increasing the temperature of the pretreatment of the CNTs from 600 to 900 °C enhanced the fraction of cobalt oxide nanoparticles encapsulated in the channels of the CNTs from 31% to 70%. The performance of Co/CNTs in Fischer–Tropsch synthesis (FTS) was evaluated in a fixed-bed microreactor at a temperature of 240 °C and a pressure of 2.0 MPa. The highest CO conversion obtained over Co/CNTs pretreated at 900 °C was 59%, which dropped by ~3% after 130 h of time on stream. In contrast, the maximum CO conversion obtained using Co/CNTs pretreated at 600 °C catalysts was 28%, which decreased rapidly by about 54% after 130 h of time on stream. These findings show that the combined acid and thermal pretreatment of the CNT support at 900 °C improved the stability and activity of the Co/CNTs catalyst in FTS.