A Process Integration Approach to the Optimization of CO2 Utilization via Tri-Reforming of Methane

Abstract

Abstract Dry reforming of methane (DRM) utilizes two greenhouse gases; carbon dioxide (CO2) and methane (CH4) to produce a syngas mixture of carbon monoxide (CO) and hydrogen (H2), which is a very important precursor for the production of a variety of valuable chemicals and liquid fuels. Although DRM offers important advantages for sequestering CO2, its utilization is challenged by certain critical process limitations such as carbon deposition, high energy requirements and low quality of H2:CO ratio. Due to these limitations, DRM process has always been a grey area demanding more research for its successful implementation at an industrial scale. Much of the work recently reported in the literature suggests the utilization of the combination of the conventional reforming technologies like steam reforming (SRM) and partial oxidation (POX) to tackle these limitations. The objective of this work is to develop a process integration approach to the optimization of a process involving DRM, SRM, and POX. As an extension to our previous work involving the optimization of the various operating parameter’s involved in Tri-Reforming (Challiwala et al. 2017), this work is aimed at mass and heat integration of the overall process to determine important benchmarks and to couple the reforming system with the rest of the process. Detailed kinetic and thermodynamic aspects are used to provide a high-fidelity model of the reforming system. The results from the thermodynamic study have been validated by using different combinations of the Langmuir-Hinshelwood-Hougen-Watson (LHHW) based kinetic models pertaining to DRM, POX and SRM processes individually. In particular, the major advancement in this work shows that the combination of individual kinetic models of different systems could be compatible to each other to predict the behaviour of the combined DRM/SRM/POX system and to exploit synergism with mass and energy from the rest of the industrial process. Validation of the results shows excellent agreement between thermodynamic and kinetic product profiles. In addition to this, the combined kinetic model was used to simulate a pseudo-homogeneous fixed bed reformer reactor in MATLAB® and further extended in COMSOL® simulation package to investigate the effect of the transport resistances present in the system under localized conditions of the catalyst bed. The proposed work is carried out at different scales and is conducive to multi-scale system integration and optimization.