Grantee Research Project Results
2004 Progress Report: Improved Combustion Catalysts for NOx Emission Reduction
EPA Grant Number: R831276C015Subproject: this is subproject number 015 , established and managed by the Center Director under grant CR831276
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
Center: Texas - Indiana Virtual STAR Center
Center Director: Gustafsson , Jan-Ake
Title: Improved Combustion Catalysts for NOx Emission Reduction
Investigators: Richardson, James T.
Institution: University of Houston - University Park
EPA Project Officer: Aja, Hayley
Project Period: December 1, 2003 through November 30, 2004
Project Period Covered by this Report: December 1, 2003 through November 30, 2004
Project Amount: Refer to main center abstract for funding details.
RFA: Gulf Coast Hazardous Substance Research Center (Lamar University) (1996) RFA Text | Recipients Lists
Research Category: Hazardous Waste/Remediation , Targeted Research
Objective:
The objective of this research project is to reduce emissions of NOx from natural gas combustion processes by using catalysts supported on ceramic foams rather than monoliths as usually practiced. The rational is that more turbulent flow in ceramics foams creates better mixing in the combustion zone and avoids the creation of hot spots that produce excessive NOx.
Progress Summary:
Ceramic foams tested were 30-pores per inch (ppi) samples of α-Al2O3, ZrO2, and cordierite, but α-Al2O3 gave the best overall performance, in terms of activity, stability, and mechanical strength. The combustion catalyst used was BaMn hexa-aluminate (BaMnxAl11-xO19), because it is both a washcoat and active component and displays excellent adherence to α-Al2O3 at elevated temperatures.
A standard preparation method was used in which a mixed hydrogel is coprecipitated from nitrate solutions using ammonium carbonates, the slurry aged, filtered, washed and dried, and then calcined at an optimum temperature of 1200°C giving 95 percent BaMnxAl11-xO19 with a surface area of 25 m2g-1.
A less time-consuming procedure was developed in which BaO2, MnO2, Al metal, and α-Al2O3 were combusted internally to generate temperatures necessary to drive the solid state reaction forming a well crystalline phase of 99 percent BaMnxAl11-xO19 (12.6 m2g-1).
It was found that catalytic activity for combustion increased with x in BaMnxAl11-xO19 but the surface areas decreased above x = 1, showing that the optimum composition was BaMnAlxO19.
A procedure was developed for washcoating the foams by dipcoating from a slurry of BaMnxAl11-xO19. A semiquantitative ultrasound vibration measure of adherence showed that α-Al2O3, ZrO2, and cordierite foams produced strong washcoats.
Catalytic tests during repeated temperature cycles using an automated unit gave conversion curves, kinetic rate constants, and were a measure of thermal stability. The original activity of the powder is retained when washcoated onto the foam, but the foam is much more stable. Low amounts of NOx (2-3 ppm) were recorded, and first-order kinetics for CH4 with an activation energy of 112 kJ mol-1 were indicated over the complete conversion range, implying that chemical kinetics prevailed with little or no transport resistance.
Comparison of a washcoated cordierite monolith with an equivalent foam showed a dramatic differences. The monolith ignited at 725°C, rapidly reaching full conversion, with evidence of multiplicity, hysteresis, and increased NOx formation, indicative of hot spot formation. The foam, however, displayed no hysteresis or NOx formation.
This research confirms that BaMn hexa-aluminate can be washcoated onto ceramic foams that are thermally more stable than monoliths under the same test conditions for catalytic combustion.
Future Activities:
Long-term (> 1000 hours) activity tests will be conducted at operational temperatures to assess stability. Kinetic and other properties resulting from this research will be incorporated into a mathematical model to be used for comparisons under real conditions (i.e., at space velocities much higher than possible with the laboratory apparatus). This will then lead to commercial-scale designs with which economic and engineering feasibility studies can be pursued.
Journal Articles:
No journal articles submitted with this report: View all 1 publications for this subprojectSupplemental Keywords:
waste, ecological risk assessment, environmental engineering, hazardous waste, advanced treatment technologies, bioremediation, contaminated waste sites, groundwater contamination, petroleum contaminants, hydrocarbon,, RFA, Scientific Discipline, Air, Toxics, Waste, INDUSTRY, POLLUTANTS/TOXICS, Chemical Engineering, air toxics, Environmental Chemistry, Chemicals, Chemistry, HAPS, Industrial Processes, Incineration/Combustion, Engineering, Engineering, Chemistry, & Physics, Environmental Engineering, Nitrogen Oxides, NOx reduction, Nox, combustion byproducts, VOC removal, air pollution control, combustion emissions, combustion technology, combustion, VOC emission controls, nitrogen oxides (Nox), exhaust, catalytic combustion, VOC treatment, Volatile Organic Compounds (VOCs), air qualityRelevant Websites:
http://dept.lamar.edu/gchsrc/ Exit
Progress and Final Reports:
Original AbstractMain Center Abstract and Reports:
CR831276 Texas - Indiana Virtual STAR Center Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
R831276C001 DNAPL Source Control by Reductive Dechlorination with Fe(II)
R831276C002 Arsenic Removal and Stabilization with Synthesized Pyrite
R831276C003 A Large-Scale Experimental Investigation of the Impact of Ethanol on Groundwater Contamination
R831276C004 Visible-Light-Responsive Titania Modified with Aerogel/Ferroelectric Optical Materials for VOC Oxidation
R831276C005 Development of a Microwave-Induced On-Site Regeneration Technology for Advancing the Control of Mercury and VOC Emissions Employing Activated Carbon
R831276C006 Pollution Prevention through Functionality Tracking and Property Integration
R831276C007 Compact Nephelometer System for On-Line Monitoring of Particulate Matter Emissions
R831276C008 Effect of Pitting Corrosion Promoters on the Treatment of Waters Contaminated with a Nitroaromatic Compounds Using Integrated Reductive/Oxidative Processes
R831276C009 Linear Polymer Chain and Bioengineered Chelators for Metals Remediation
R831276C010 Treatment of Perchlorate Contaminated Water Using a Combined Biotic/Abiotic Process
R831276C011 Rapid Determination of Microbial Pathways for Pollutant Degradation
R831276C012 Simulations of the Emission, Transport, Chemistry and Deposition of Atmospheric Mercury in the Upper Gulf Coast Region
R831276C013 Reduction of Environmental Impact and Improvement of Intrinsic Security in Unsteady-state
R831276C014 Integrated Chemical Complex and Cogeneration Analysis System: Greenhouse Gas Management and Pollution Prevention Solutions
R831276C015 Improved Combustion Catalysts for NOx Emission Reduction
R831276C016 A Large-Scale Experimental Investigation of the Impact of Ethanol on Groundwater Contamination
R831276C017 Minimization of Hazardous Ion-Exchange Brine Waste by Biological Treatment of Perchlorate and Nitrate to Allow Brine Recycle
R831276C018 Integrated Chemical Complex and Cogeneration Analysis System: Greenhouse Gas Management and Pollution Prevention Solutions
The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.
Project Research Results
Main Center: CR831276
64 publications for this center
18 journal articles for this center