The objective of this project is to develop a cost effective, process intensified modular technology for the conversion of flare gas (methane, ethane and C3+ alkanes) to carbon nanotubes (CNTs) and carbon fibers (CNFs). This will be accomplished through the exploitation of microwave-specific effects on the catalytic pyrolysis of natural gas. The use of microwaves to drive this reaction has been clearly demonstrated to make the conversion of natural gas by this process both kinetically and energetically favorable at lower temperatures. The technology development is focused on single-step conversion of methane to crystalline CNTs and fibers to demonstrate great scalability of production and recovery of the valuable solid carbon.  Specifically, this approach integrates microwave reaction chemistry into the modular reactor design with the goal to achieve energy and capital efficiency comparable or better than large commercial unit operation. Major focus will be on the application of process intensification at modular component scales with the objective of deployment at flare gas locations, particularly, at a pilot demonstration unit.  A modular component having a large turndown ratio which can operate under varying feed rate and composition will be demonstrated. It is anticipated that the technology readiness level (TRL) will be increased from TRL 4 to 5.

West Virginia University Research Corporation – Morgantown, WV 26506
North Carolina State University – Raleigh, NC 27695
H Quest Vanguard – Pittsburgh, PA 15238
Pacific northwest National Laboratory – Richland, WA 99352
C4-MCP LLC – Santa Monica, CA 90404
 

Over 200 billion ft³/year of natural gas at remote production sites is rejected via flaring in the U.S due primarily to the limitations in pipeline transportation capacities or fluctuation in the well production rate. This is a significant waste of valuable resources and unrealized profit. A process intensified modular unit appears to be promising in converting flared gas to value-added solid carbon and hydrogen. The modular equipment will be able to be deployed and transported between remote locations.

The technology is based on microwave-enhanced, multifunctional catalytic system to directly convert the light components of stranded natural gas. Specifically, the approach integrates microwave plasma reaction chemistry into the modular reactor design with the goal to achieve energy and capital efficiency comparable or better than large commercial unit operation. Microwave plasmas are non-homogeneous in spatial and temporal dimensions. In the excitation region, the microwave electromagnetic field couples and transfers its energy to the free electrons in the gas.  Major focus will be on the application of process intensification at modular component scales with the objective of deployment at flare gas location. Particularly, the project will demonstrate the modular component having a large turndown ratio which can operate under varying feed rate and composition at stranded natural gas locations.

Successful completion of this project will provide a scientific basis and methodology to produce carbon nanotubes and carbon nanofibers from stranded natural gas. The carbon nanotubes and fibers can be used in polymers, plastics, batteries and electrodes for electric arc steel making. This process, if successfully developed and deployed, will reduce the volume of natural gas being flared to the atmosphere, thereby having a positive effect on the environment.

The technology will open a new way for converting stranded natural gas to value added solid carbons. The development of natural gas conversion to CNTs and CNFs, will boost the economic infrastructure of the regions which is vital to the future economy. The produced carbon can be sold as a co-product, thus providing an economic credit that reduces the delivered net cost of hydrogen. The CNTs and CNFs are high-value products used in polymers, plastics, batteries, carbon composites and electrodes, having attractive properties such as electrical conductivity, high tensile strength, high thermal stability, and chemical stability.

Electromagnetic sensitive catalysts were synthesized and tested in methane pyrolysis reaction under microwave irradiation.  Dielectric heating properties and conductive heating properties of these catalysts were analyzed and correlated with the catalytic performance. 

Three different catalyst formulations and synthesis protocol have been developed. The formulation strategy is focused on catalysts having strong metal-support interaction that facilitates recovery of carbon nanomaterials. 
A kinetic model has been built and validated with microwave reactor data. In addition, process simulation and technoeconomic analysis (TEA) models have been built. 

Microwave plasma reactor design, installation and commissioning activities have been completed. Cold flow test and hot reactor test with Ni/Pd/CNT catalyst were performed. The pilot reactor design was further improved to test another process scenario-micro plasma. A new process concept based on single-stage two process zones were developed and tested in pilot plant.

WVU has filed a full utility patent based on the provisional patent (background IP). Two journal articles were published in Industrial & Engineering Chemical Research: https://pubs.acs.org/action/showCitFormats?doi=10.1021/acs.iecr.1c05082&ref=pdf and Chemical Engineering Journal: https://doi.org/10.1016/j.cej.2022.140115

The Principal Investigator (PI) made several invited presentations including DOE Hydrogen Energy EarthShot Summit.

Catalytic performance tests in both a fixed frequency and a variable frequency microwave reactors will be conducted. A mixture of methane and ethane that simulates wellhead flaring gas composition was tested in microwave pyrolysis reactor. The conversion of ethane is proved to be much easier than methane, i.e., near 100%. The results are encouraging because the condensate (C2+) can be preferentially converted to hydrogen can CNT. If the catalyst and process are optimized, this is a way to clean up shale gas to pipeline grade without installing gas separation units. Several proof-of-concept configurations of pilot-scale fluidized bed microwave system were implemented and evaluated with catalyst stand-ins such as carbon blacks and NiPd/CNT catalysts. Reactor configurations include fluidized and spouted catalyst entrainment, as well as direct flow entrainment were explored.  Fluidization characteristics were evaluated with both catalyst stand-ins and CNT supports first in cold, and then in hot (microwave plasma) tests. Commission tests with CNT supports and Pd/Ni/CNT catalysts test were completed with methane microwave plasma. Microwave plasma catalytic pyrolysis was carried out. A new reactor configuration was tested by placing catalyst at the end of plasma zone to control the pyrolysis reaction temperature. The results will be used to compare with single plasma reaction zone approach. Base-growth catalysts continue to be designed and tested. TEA models continue to be updated throughout the entire project duration. Base growth TEA analyses currently show that with reasonable carbon selling price, a hydrogen price of $1/kg H2 will be able to be achieved without factoring in carbon tax or credit. The team is continuing to scale up catalyst synthesis protocol to make catalyst for the microwave plasma pilot reactor at H-Quest. Laboratory reactor data are used to guide pilot operation. The team is focusing on translating fixed-bed reactor operation to fluidized-bed pilot operation, targeting production rate of ~5 kg/day CNTs.

$2,999,991.00

$791,221.00

NETL – Gary Covatch (Gary.Covatch@netl.doe.gov or 304-285-4589)
West Virginia University Research Corporation – Jianli (John) Hu (John.Hu@mail.wvu.edu or 304-293-5067)