Kinetic and Thermodynamic Aspects for CO2 Conversion to Methanol via Trireforming

Long term viability of the petroleum refinery sector must include a sustainable infrastructure whereby the triple bottom line – profit, people, and planet – is sought.  One such avenue is development of alternate strategies of CO₂ conversion technologies, such as tri-reforming.  Tri-reforming is a combination of methane steam reforming, CO₂ reforming, and methane oxidation that utilizes the steam and CO₂ released from flue stack gases and converts to syngas (CO and H₂).  Unlike typical sequestration technologies that require CO2 to be separated from steam before being pumped underground, tri-reforming avoids this expense by using the mixed CO2 and steam.  Conversion of carbon dioxide, if economically viable, extents our carbon resources and reduces our carbon footprint. 

            A thermodynamic analysis, along with a process simulation and optimization analysis, was conducted using Aspen simulation coupled to a General Algebraic Modeling System (GAMS), for the combined tri-reforming/methanol synthesis paradigm.  Model parameters for the tri-reformer included temperature (400 – 1,200°C), pressure (1 – 5 atm), and CH4/Flue gas ratio (0.4 – 1.0).  Results showed that high temperatures and low pressures favored high CO2 conversions with an optimum H₂/CO = 2. Furthermore, an economic analysis demonstrated substantial profits when the endothermic tri-reforming process was coupled to the highly exothermic methanol synthesis process. 

            In an additional study, a novel catalyst has been developed for the tri-reforming reaction that uses reverse micelles to create nano-sized Transition metal reactive sites onto the surface of TiO₂ anatase.  The anatase, which has oxygen vacancies within its lattice structure, was found to be not just a surface area providing support but an active component within the overall operability of the catalyst.  A kinetic evaluation and a time on stream analysis have shown to have better performance than a traditional steam methane reforming catalyst.  The overall study demonstrates a viable, sustainable method that has the potential of economically reducing pinpoint CO₂ emissions. The complete catalyst development and kinetic evaluation, along with the Aspen simulation study, will be shown.