Tag Archives: carbon

A Robust High-Temperature Semiconducting Carbon Monoxide (CO) Sensor

Posted on by

Summary:

In many combustion-related industries, monitoring CO levels is critical for estimating the efficiency of the combustion process. With the ideal balance of oxygen to fuel, pollution is also minimized. Existing gas sensors based on metal oxide materials typically operate at 200-300 degrees C. Researchers at The Ohio State University have developed a CO sensor for hostile industrial environments (450-800 degrees C) that responds to CO at concentrations approaching one part per million. These sensors can be miniaturized with minimal electrical power requirements, and exhibit stable baseline resistance and good response and recovery times. To the best of our knowledge, we know of no existing solid state sensors that equal the performance of these sensors.

Potential Applications:

  • Combustion control
  • Heat treating
  • Metal processing and casting
  • Glass and ceramics manufacturing
  • Food processing
  • Power plant operations
  • Automotive applications

Advantages:

  • Responds to CO at ppm levels
  • Can be used in high-temperature, hostile environments (450-800 degrees C)
  • Minimal drift
  • Quick recovery times
  • More economical than existing high-temperature sensor technologies

Low Temperature Synthesis of Carbon Clusters Enriched with 13C and 14C Isotopes

Posted on by

Summary:

The need of carbon clusters, mainly multi-walled and single-walled carbon nanotubes as well as fullerenes, has be increasing exponentially over the past decade as such materials are finding their way out of the research lab and into commercial products. These fascinating materials have received a great deal of interest because of their useful properties such as extreme hardness, low density, and variable conductivity. Particularly, single-walled carbon nanotubes (CNTs) have many unique and potentially useful physical and chemical properties. Conventional process techniques generally used for the creation of these CNTs require production temperatures around 1000 Celsius thereby resulting in large energy consumption. These high temperatures also preclude the synthesis of complex carbon structures (including ones containing metal catalysts) as such structures would be unstable and would dissociate at elevated temperatures. Furthermore, conventional production methods result in isotope 12C-enriched CNTs and not the more enticing 13C and 14C isotopes. As a reaction to this demand for low temperature, low energy consumption carbon clusters that are 13C- and 14C-enriched, researchers at The Ohio State University have patented a novel technique for CNT production at or below 100 Celsius which also leads to the formation of more advanced CNT materials with a highly aligned structure.

Potential Applications:

  • Electronics
  • Field emission devices
  • Composites
  • Building structures
  • Energy storage (fuel cells and batteries)
  • Sporting equipment, body armor and consumer clothing
  • Aerospace
  • Automotive

Advantages:

  • Allows for the efficient production of 12C-enriched single-walled CNTs, multi-walled CNTs and fullerenes as well as carbon clusters significantly enriched in heavy carbon isotopes (13C, 14C)
  • Minimizes energy consumption by requiring process temperatures of 100 Celsius instead of the conventional processes that require 1000 Celsius
  • Allows for the synthesis of complex carbon structures (including ones containing metal catalysts) at temperatures where these products remain stable
  • Production levels comparable to conventional high temperature processes

One-Step Chemical Looping Process for Producing Hydrogen or Syngas directly from Solid Fuels

Posted on by

Summary:

Researchers at The Ohio State University have developed a one-step, highly efficient Chemical Looping Reforming (CLR) process to produce H2, CO or a mixture thereof (syngas) directly from solid carbonaceous fuels like coal and biomass, eliminating the need for a gasifier. The novel process utilizes cyclic redox reactions of metal oxide (MO) particles.

Fe2O3 is used as the metal oxide for this process. This approach resolves the problems that are conventionally encountered due to the introduction of coal (tar formation, char conversion, caking of coals, sulfur handling, and ash handling). The reactions of coal and Fe2O3 have been demonstrated on a bench scale reactor with significant success. Detailed ASPEN studies have shown that hydrogen production efficiencies (high heating value – HHV basis) ranging between 80-90% are possible. Preliminary cost analysis suggests a significant reduction in the cost of hydrogen as compared to the SMR (steam methane reforming) process for natural gas.

The process introduces coal directly into the first reactor that allows complete conversion of Fe2O33 to Fe, and forms a ready to sequester CO2 stream after condensation of water. The CLR process can also be used instead of a gasifier to produce syngas. The process can provide any H2/CO ratio desired in the syngas stream with limited CO2 concentration. Additionally, optimizing iron oxide particles has led to the development of strong particles durable at high temperatures, demonstrated to maintain full oxygen transfer capacity over a 100 cycles of reduction and oxidation.

Potential Applications:

  • Centralized large scale hydrogen production: Uses in oil refining, ammonia manufacture
  • Coal gasification to produce syngas for liquid fuels or electricity production
  • Suitable for making Fe particles which can be used for hydrogen storage and producing electricity via fuel cells

Advantages:

  • Elimination of gasifier and air separation unit
  • Integrated CO2 separation design with no costly separation techniques offering several environmental benefits
  • Fuel flexibility allowing for all kinds of solid carbonaceous fuels such as coal, wood, biomass, pet coke, tar sand, and shale rock
  • Can help tailor H2/CO ratio of syngas to any desired level
  • High hydrogen production efficiency (80-90%)
  • Over 30% costs savings over traditional processes
  • Smaller plant footprint due to lesser number of reaction vessels, resulting in a simpler process control
  • Produces low cost Fe2O3 composite particles, shown to undergo more that 100 redox cycles without loss in activity

Carbon Monoxide (CO) Detector Operating at Room Temperature

Posted on by

Summary:

Existing CO sensors are usually of either the electrochemical or optical variety. Inexpensive optical sensors, usually battery powered, are limited in their precision and lack displays to determine exact levels of CO concentration. Electrochemical devices offer higher precision and offer a display for CO concentration, but must operate at elevated temperatures and thus must be plugged in to a wall outlet. Researchers at The Ohio State University have developed an electrochemical CO sensor that operates and senses CO at room temperature, thus eliminating the need for a heating device. Therefore, energy demands are far lower when plugged in to a wall outlet, and a battery-powered electrochemical CO sensor can be achieved. This sensor can monitor CO in the ppm range and can be readily fabricated by screen printing techniques with deposition on polymer substrates. Sensors are miniaturizable.

Potential Applications:

  • Home, office, and industrial CO monitoring for occupant safety and fire detection
  • CO sensors can be incorporated into mobile devices, such as cell phones

Advantages:

  • Increased safety and sensor longevity as no heating device is needed
  • For the first time, battery-powered electrochemical CO sensors are possible
  • A portable, battery-powered CO sensor with a display becomes possible
  • Great reduction in energy consumption
  • Low-cost and easy to manufacture

Humidity-Interference Free, High-Temperature CO2 Sensor

Posted on by

Summary:

Carbon dioxide sensors are becoming increasingly important in many applications including monitoring air quality, CO2 sequestration, measuring metabolic activity in animals, and controlling combustion. While commercial sensors for such applications exist, there is nothing currently on the market designed for reliability and effectiveness in high temperature and high humidity environments. Researchers at The Ohio State University have developed a reliable, high-performance carbon dioxide electrochemical sensor that works across a wide range of temperatures, is insensitive to humidity, and detects CO2 across a wide range of concentrations. These sensors can be manufactured by thin and thick film processing techniques, and can therefore be miniaturized resulting in a sensor with milliwatt power requirements for operation.

Potential Applications:

  • Combustion control
  • Monitoring of metabolic activity
  • CO2 monitoring in harsh environments
  • Power plant and industrial emissions monitoring
  • Automotive and aerospace emissions monitoring
  • CO2 sequestration applications

Advantages:

  • Humidity-interference free
  • Fast response and recovery
  • Long-term sensor stability in humid conditions over a wide range of temperature
  • Solid-state device

Graphene Composites as the Cathode Material of High-Power Lithium Ion Batteries

Posted on by

Summary:

Lithium ion batteries, commonly found in today’s mobile devices, are poised to play a major role in serving our future energy needs. While current batteries are suitable for mobile phones and laptops, their energies and power densities are insufficient for more demanding applications such as transportation and mass energy storage. The major limiting factor in lithium ion battery performance is in the cathode material, and various materials have been identified that offer large capacity, low cost, chemical stability, and environmental friendliness. Unfortunately, these materials also suffer from very poor electrical conductivity. Much research has focused on forming composites of these materials with different kinds of carbons, conductive polymers, metals, and oxides in order to alleviate this issue, with little success. Researchers at The Ohio State University have developed composites of these materials with graphene (planar atomic sheets of graphite) that exhibit excellent electrical conductivity while maintaining the beneficial properties noted above. The researchers have developed one type of graphene composite that boosted the electrical conductivity (compared to the material alone) by eight orders of magnitude. Amazingly, in this case graphene only makes up 3.6% of the composite by weight! Other material systems and methods of manufacture have been developed, and continue to be investigated, that could yield even more impressive results.

Potential Applications:

  • High density energy storage for alternative energy sources
  • Transportation (e.g. hybrid and plug-in electric vehicles)
  • Mobile devices (enables much longer life and better performance with a smaller battery)

Advantages:

  • A major breakthrough in the quest for high performance lithium ion batteries with large energy densities
  • Enables an environmentally friendly cathode material that exhibits large capacity, low cost, chemical stability, and high electrical conductivity
  • In one test, adding as little as 3.6% graphene by weight boosted the electrical conductivity of a material by eight orders of magnitude
  • Low carbon content in electrodes due to the use of graphene (3.6% by weight) results in enhanced overall gravimetric and volumetric capacities
  • Exhibits superior rate capability, maintaining ~70% capacity at 20 C

High-Performance, Economically-Viable Membranes for Carbon Dioxide (CO2) Separation

Posted on by

Summary:

Economically viable removal of CO2 from sources such as coal plant flue gas and gasification mixtures requires affordable separation membranes that have high selectivity combined with high flux. State of the art membranes do not meet these requirements. Researchers at The Ohio State University have developed a new ultrathin inorganic membrane that exhibits high selectivity and a potentially high permeance for the separation of CO2 with respect to other gases. The membrane exhibits long-term stability, and operations over a wide range of temperatures.

Potential Applications:

  • Fuel Cells
  • Power Plants
  • CO2 recovery from fossil fuel combustion sources

Advantages:

  • Achieves both high CO2 selectivity and high flux
  • Can be easily manufactured

Low Temperature Working Carbon Monoxide (CO) Sensor Based on Au/SnO2 Core-Shell Nanoparticles

Posted on by

Summary:

SnO2-based CO sensors are widely used in domestic and industrial applications and belong to the class of metal-oxide semiconductor (MOS) sensors. This class of sensor is easy to manufacture and miniaturize, and sensitivity and selectivity are both tunable. Also, electrochemical measurements are easily realized, require simple electronics, and integration into electronic devices is straightforward. However, since sufficient oxygen vacancies are needed for conduction, MOS sensors typically operate at elevated temperatures, which requires energy consumption and reduces sensor lifetimes. Researchers at The Ohio State University have developed a MOS CO sensor based on Au/SnO2 core-shell nanoparticles that is operable in the 25 to 150 deg. C range. Sensor response is highly reproducible and recovery is fast in this temperature range, and high sensitivity was exhibited.

Potential Applications:

  • Home, office, and industrial CO monitoring for occupant and fire safety
  • Low temperature and low power requirement makes it compatible with mobile devices

Advantages:

  • A MOS electrochemical CO sensor that operates in the 25 to 150 deg. C range!
  • Increased safety and sensor longevity as no heating device is needed
  • Greatly reduced energy consumption
  • Extremely low cost and easy manufacturing
  • Simple electronics for easy device integration

A High-Efficiency Chemical Looping Process to Produce Low-Cost Hydrogen from Gaseous Fuels

Posted on by

Summary:

Researchers at The Ohio State University have developed a highly efficient chemical looping process that utilizes cyclic redox reactions of metal oxide (MO) particles with gaseous fuels (like syngas and natural gas) and steam to produce hydrogen. Named as SynGas Redox (SGR), the process as developed is a marked improvement over the conventional Steam-Iron process to produce hydrogen.

MO + CO/H2/CH4 <-> M + CO2 + H2O
M + H2O <-> MO + H2

The primary metal oxide in SGR is Fe2O3 which is converted to Fe on reaction with syngas. The reactor design allows for a complete conversion of syngas to a mixture of carbon dioxide and water, exiting the reactor using the same high pressure of the gasifier. Upon condensation of water, a relatively pure stream of carbon dioxide is produced which is ready for sequestration. The iron oxide is regenerated in a second reactor, the design of which is also optimized for maximum conversion of steam to hydrogen.

The process has been demonstrated on a bench scale reactor with significant success, including detailed ASPEN simulations. The process has also been optimized (and integrated) for syngas derived from a commercially available dry feed bituminous coal gasifier. Close to 75% of the coal HHV (high heating value) can be converted to hydrogen HHV, suggesting a much higher efficiency than the conventional coal gasification-water gas shift route to hydrogen. Preliminary cost analysis suggests a significant reduction in the cost of hydrogen as compared to the SMR (steam methane reforming) process for natural gas. The process can be further adapted to Coal-To-Liquids(CTL) plants to utilize by-products from the Fischer-Tropsch reactor, resulting in a higher (over 10%) yield of liquid fuels and a significant reduction in operational costs by handling carbon dioxide separation more efficiently. Additionally, optimizing iron oxide particles has led to the development of strong particles durable at high temperatures, demonstrated to maintain full oxygen transfer capacity over a 100 cycles of reduction and oxidation.

Potential Applications:

  • Centralized large scale hydrogen production: Uses in oil refining, ammonia manufacture
  • Coal to Liquid (CTL) plants
  • Suitable for making Fe particles which can be used for hydrogen storage and producing electricity via fuel cells

Advantages:

  • Integrated CO2 separation, with no costly separation techniques. Provides ready to sequester CO2 stream by design, offering several environmental benefits
  • Fuel flexibility, allowing for all kinds of gaseous carbonaceous fuels such as syngas, producer gas, natural gas, and fuel cell exhaust
  • Can help tailor H2/CO ratio of syngas to any desired level
  • High hydrogen production efficiency (80-90%)
  • Over 15% costs savings over traditional processes
  • Easily adaptable for integration with CTL plants, resulting in cost reductions
  • Produces low cost Fe2O3 composite particles, shown to undergo more that 100 redox cycles without loss in activity