Carbon nanotubes and hydrogen production from the reforming of toluene

Abstract

Catalytic steam reforming of liquid hydrocarbons is one of the promising alternatives for hydrogen production. However, coke deposition on the reacted catalyst results in catalyst deactivation and also CO2 emission during reforming are among the main challenges in the process. In this work, the production of high-value carbon nanotubes (CNTs) during hydrogen production from catalytic reforming of toluene has been investigated. Thus, less carbon emission and higher product values can be expected from the process. A two-stage fixed bed pyrolysis-reforming reactor was used in this work. The results showed that the addition of a Ni–Mg–Al catalyst, with an additional downstream stainless steel mesh, increased hydrogen production from 24.8 to 54.8 (mmol H2 g−1 toluene), when water (steam) was injected at a rate of 0.01 g min−1. CNTs were also produced in the process in the presence of the Ni–Mg–Al catalyst and with a water injection rate of 0.01 g min−1 had the highest band ratio of G′/G when analyzed by Raman spectrometry, indicating the highest purity of CNTs. In addition, Raman spectra of the generated CNTs showed that the purity of CNTs was reduced with the addition of water for reforming without the Ni–Mg–Al catalyst. The presence of the Ni–Mg–Al catalyst significantly increased the yield of CNTs formed on the surface of the stainless steel mesh and also improved the quality of the CNTs in relation to the distribution of diameters and their length.