Carbon dioxide capture and utilization is becoming the key concern for investment in the energy and industrial sector due to ever increasing carbon emissions and growing concerns about climate change among public and government agencies around the world. While significant time and effort has been spent on finding new and innovative methods of capturing CO2 from the atmosphere and industrial emissions, methods of utilizing this CO2 remain to be fully developed. As Carbon Capture and Storage (CCS) technologies have advanced in recent years, the concept of CO2 utilization has attracted more interest due to the potential of CO2 as a useful chemical commodity to produce value-added chemicals, such as methane and methanol. The utilization of CO2 to produce methane via the Sabatier reaction is one potential solution to this challenge. This process produces methane and water by reacting CO2 with hydrogen. The methane generated can be used directly as a fuel or it can be converted into higher molecular weight hydrocarbons which can be transported or stored in liquid form.
Precision Combustion, Inc. (PCI), with support from NASA Small Business Innovation Research (SBIR) awards, has developed a novel efficient and compact Sabatier (i.e., CO2 methanation) reactor based on its Microlith® catalytic technology to convert the captured CO2 to produce methane. Our approach demonstrated the capability to achieve high CO2 conversion and CH4 selectivity (i.e., ≥90% of the thermodynamic equilibrium values) at high space velocities, low operating temperatures, and low H2 requirements. The ability to achieve high CH4 yield was made possible through the use of high-heat-transfer and high-surface-area Microlith catalytic substrates. PCI’s novel approach permits reactor operation under exothermic conditions with efficient heat recuperation for high catalyst performance at high space velocities and extended catalyst lifetime. A key advantage is the ability of the reactor to efficiently sustain its temperature during the CO2 methanation reaction via an efficient heat recuperator and heat exchanger, thus eliminating the need for an external heat source, resulting in minimal power usage during steady state operation.
Using this Sabatier reactor, PCI designed, developed, and demonstrated a stand-alone CO2 methanation test system for demonstration and performance validation. The Sabatier reactor was integrated with the necessary balance-of-plant (BOP) components and control system, allowing an automated, single “push–button” start-up and shutdown. All of the BOP components were commercial off-the-shelf and the control system was developed in-house using National Instrument hardware and LabView software. The versatility of the test system prototype was demonstrated by operating it under H2-rich (H2/CO2 of >4), stoichiometric (ratio of 4), and CO2-rich conditions (ratio of <4) without affecting its performance and meeting the equilibrium-predicted CH4 yield and throughput. In this presentation, the development of the Microlith-based CO2 methanation reactor and the test system assembly for demonstration and performance validation will be discussed. Additionally, the performance results from testing the system for converting CO2 to methane at various operating conditions and the results from the 1000-hr durability testing will be presented.