Low-Temperature Oxidation/ Reduction Catalysts
materials and coatings
Low-Temperature Oxidation/
Reduction Catalysts (LAR-TOPS-124)
Catalytic oxidation of carbon monoxide,
formaldehyde, and other hydrocarbons, and NOx
reduction, in air and process gas streams
Overview
NASA Langley researchers, in work spanning more than a decade, have developed a portfolio of technologies for low-temperature gas catalysis. Originally developed to support space-based CO2 lasers, the technology has evolved into an array of performance capabilities and processing approaches, with potential applications ranging from indoor air filtration to automotive catalytic converters and industrial smokestack applications. The technology has been used commercially in systems that provide clean air to racecar drivers, as well as incorporated into commercially available filtration system for diesel mining equipment. Backed with extensive research on these technologies, NASA welcomes interest in the portfolio for other commercial and industrial applications.
The Technology
The low-temperature oxidation catalyst technology employs a novel catalyst formulation, termed platinized tin oxide (Pt/SnOx). The catalysts can be used on silica gel and cordierite catalyst supports, and the latest developments provide sprayable formulations for use on a range of support types and shapes. Originally developed for removal of CO, the catalyst has also proven effective for removal of formaldehyde and other lightweight hydrocarbons.
NASA researchers have also extended the capability to include reduction of NOx as well as developed advanced chemistries that stabilized the catalyst for automotive catalytic converters via the engineered addition of other functional components. These catalyst formulations operate at elevated temperatures and have performed above the EPA exhaust standards for well beyond 25,000 miles. In addition, the catalyst can be used in diesel engines because of its ability to operate over an increased temperature range.
For use as a gas sensor, the technology takes advantage of the exothermic nature of the catalytic reaction to detect formaldehyde, CO, or hydrocarbons, with the heat being produced proportional to the amount of analyte present.
Benefits
- Temperature range: room temperature to several hundred degrees Celsius
- Oxidation removal of CO, formaldehyde, and other lightweight hydrocarbons
- Can be formulated for reduction of NOx
- Standard treatment available for silica and cordierite ceramic substrates
- Sprayable formulations available for catalyst treatment onto a variety of other substrates and substrate forms
- No external heating or energy input required for operation
- Readily available materials and manufacturing methods
- Extensive history and experience at NASA for applications development and performance characterization
Applications
- Automotive exhaust catalytic converters
- Industrial process control
- Smokestack emission remediation
- Indoor air treatment
- Cabin air treatment
- Contained breathing systems
- Diesel operated machinery
Similar Results
Advanced Hydrogen and Hydrocarbon Gas Sensors
In conjunction with academia and industry, NASA's Glenn Research Center has developed a range of microelectromechanical systems (MEMS)-based and Silicon Carbide (SiC)-based microsensor technologies that are well-suited for many applications. The suite of technologies includes hydrogen and hydrocarbon leak detection sensors; emissions sensor arrays; and high-temperature contact pads for wire bond connections.
Currently used to protect astronauts on the International Space Station, the hydrogen and leak detection sensors have many Earth-based applications as well. They can function as a single-sensor unit or as part of a complete smart sensor system that includes multiple sensors, signal conditioning, power, and telemetry. The system can comprise sensors for hydrogen, hydrocarbons, oxygen, temperature, and pressure. The emissions sensor array features a gas-sensing structure that detects various combustion emission species (carbon monoxide, carbon dioxide, oxygen, hydrocarbons, and nitrogen oxides) over a wide range of concentrations. In addition, the emissions sensor array remains highly sensitive and stable while providing gas detection at temperatures ranging from 450 to 600°C. These new sensors provide a combination of responsiveness and durability that offers great value for a wide range of applications and industries.
Carbonated Cement for Production of Concrete with Improved Properties
The NASA cement innovation describes a method to make solid carbon material from CO2 captured during the cement-making process, and for using that carbon material in the mixture to improve cement properties. Doing so provides a direct use for the captured CO2, eliminating any CO2 storage/disposal issues and providing an improved cement product.
The innovation employs a chemical reaction, known as the Bosch process, which uses hydrogen gas and catalysis to reduce the CO2 to solid carbon and water. Cement manufacturing is uniquely suited to the use of the Bosch process. Cement manufacturing requires high temperatures, and harnessing this excess heat limits the total energy required to maintain a Bosch process at a cement plant. Also, cement contains iron, a metal shown to be an exceptional catalyst for the Bosch process. Thus, the cement product itself can be used as the catalyst for the reaction, also serving as a carbon sink. This eliminates any requirements for the storage or disposal of the waste carbon captured from CO2 emissions.
Test evaluations at the bench scale have provided encouraging indications of enhanced mechanical properties for the carbon-containing cement materials. In particular, the findings suggest that the carbon in the concrete might delay the environmental breakdown of concrete due to the blocking effect of the carbon on harmful ions (e.g., chlorine).
Advanced Supercritical Water Oxidation Reactor
NASA's Supercritical Water Oxidation - Flame Piloted Vortex (SCWO-FPV) Reactor implements a unique design where heating is primarily supplied by the energetics of the waste stream through the control of a hydrothermal flame in the core of the reactor with the injection of fuel and oxidizer. Once the hydrothermal flame is initiated and stabilized, an outer-core "wash" stream, consisting primarily of water, is injected near the walls at the base of the reactor. This "wash" stream maintains subcritical conditions at the reactor walls, while also dissolving and/or flushing from the reactor any precipitate and non-soluble inorganic materials generated from the supercritical reactor core. Mixing between the core region and the outer subcritical flow region is largely eliminated due to the great differences in density and viscosity. The flow configuration is further stabilized by the generation of a vortex using internal structures on the inside of the reactor wall. An aspirator assembly is positioned at the top of the supercritical core region to extract treated water and un-extracted material is recirculated through the reactor. The rate and amount of aspiration will be determined by product monitoring and will depend on waste stream content and overall operating conditions. Key aspects of the technology have been demonstrated and a prototype reactor is under development.
Carbon Dioxide Gas Sensors
Current bulk or thick film solid electrolyte CO2 sensors are expensive, difficult to batch fabricate, and large in size. In contrast, this new amperometric, solid-state, oxide-based electrolyte CO2 microsensor is affordable, easy to fabricate, and is so small that it could easily be integrated onto a substrate the size of a postage stamp.
The basic composition of the sensor is identical to a previously designed NASA Glenn technology in which a solid electrolyte of Na3Zr2Si2PO12 is deposited between interdigitated electrodes on an alumina substrate and is covered by Na2CO3/BaCO3. Unlike its predecessor, however, this innovation includes an additional layer of nanocrystalline SnO2 sol gel, an electron donor type (N-type) semiconductor, on top of the Na2CO3/BaCO3 . This new layer provides a greater number of electrons for reduction reaction at the working electrode to detect CO2. As a result, overall performance is enhanced, and this new state-of-the-art sensor has the ability to operate at temperatures as low as 375°C. This low temperature capability significantly decreases the amount of power required to operate the sensor, opening the door to a multitude of new applications that were previously unattainable.
Solar Powered Carbon Dioxide (CO2) Conversion
This technology consists of a photoelectrochemical cell composed of thin metal oxide films. It uses sunlight (primarily the ultraviolet (UV), visible and Infrared (IR) portions)) and inexpensive titanium dioxide composites to perform the reaction. The device can be used to capture carbon dioxide produced in industrial processes before it is emitted to the atmosphere and convert it to a useful fuel such as methane. These devices can be deployed to the commercial market with low manufacturing and materials costs. They can be made extremely compact and efficient and used in sensor and detector applications.