Effect of High-Temperature Treatment on the Properties of Carbon Nanotube-Based Petroleum Coke Composite

Abstract

The study involved a series of experiments on the coking of vacuum residue (VR) and of a mixture of carbon nanotubes (CNTs) and VR in an autoclave at 400-550°C. Using XRD, TEM, and electrical resistivity measurements, the properties of petroleum coke (petcoke) and CNT/petcoke composite were investigated and compared with those after calcination in an inert atmosphere at 1000-1100°C. It was found that the coking of a 2.5% CNT/VR mixture reinforces the petcoke with the CNTs. The CNT/petcoke composite exhibits a slightly higher crystallinity than the petcoke. However, the resistivity of the CNT/petcoke composite was found to be more than an order of magnitude lower than that of the petcoke. After high-temperature (1000-1100°C) calcination, the difference in resistivity between the petcoke and the 2.5% CNT/petcoke composite becomes substantially lower. This is associated with a resistivity drop in the petcoke itself, which approximates the resistivity of the carbon nanotubes. It was also identified that the high-temperature calcination reduces the sulfur content in the CNT/petcoke composite, and this reduction is more dramatic than that for the petroleum coke.