Evaluation of catalysts supported on carbon nanotubes and kinetic modeling of the process for the Water-Gas-Shift reaction (WGS)

Abstract

The Water-Gas Shift (WGS) reaction is one of the most important routes for hydrogen production and for controlling H2/CO ratios in methane reforming reactions. It has received great importance due to the use of H2 in the main chemical industries (fertilizers, oil refining, etc.) and fuel cells. In addition, the H2/CO ratio control becomes relevant, for example, in the production of liquid hydrocarbons through Fischer-Tropsch synthesis, enhancing the use of natural gas over petroleum. For optimizing the WGS reaction, reversible and exothermic, consecutive stages in high (HTS) and low temperature (LTS) are used, in which catalysts of Fe2O3-Cr2O3 and Cu-ZnO-Al2O3 are generally employed, respectively. However, for portable fuel cell applications, catalysts based on noble metals at nanoscale and supported on oxides have been used due to their more resistant and suitable characteristics for this type of employment. In this context, the use of carbon nanotubes as catalysts support has shown to be advantageous due to their high surface area and the low availability of some oxides for this purpose. Moreover, determining the kinetic model and understanding the reaction mechanisms are fundamental for the reactor design and the development of new catalysts for the WGS reaction. The kinetic models most widely used to describe the process are those of Langmuir-Hinshelwood and power laws, while the two most widely verified mechanisms in the literature are the redox and the associative. The aim of this research project is to evaluate new catalysts supported on carbon nanotubes and to propose a kinetic model that best describes the WGS reaction to find innovative solutions for improving the process. (AU)