Grantee Research Project Results
Final Report: Novel Membrane Systems for Off-Road Diesel Engine NOx Reduction
EPA Contract Number: EPD04009Title: Novel Membrane Systems for Off-Road Diesel Engine NOx Reduction
Investigators: Stookey, Donald
Small Business: Compact Membrane Systems Inc.
EPA Contact: Richards, April
Phase: I
Project Period: March 1, 2004 through August 31, 2004
Project Amount: $70,000
RFA: Small Business Innovation Research (SBIR) - Phase I (2004) RFA Text | Recipients Lists
Research Category: Safer Chemicals , SBIR - Emission Reductions and Biofuels , Small Business Innovation Research (SBIR)
Description:
Compact Membrane Systems, Inc. (CMS) and its partners have been developing air separation membrane products that reduce diesel engine NOx emissions. Enriching engine air from 79 percent nitrogen to 81 percent nitrogen has reduced NOx emissions on diesel engines by as much as 50 percent. The durability of the nitrogen-enriched air (NEA) membranes has been quantified in field trials on five Caterpillar highway truck engines, and commercialization target applications have been proposed in the nonroad diesel engine market. Current NEA membranes are expected to have application in constant load, in constant speed engines such as those found in hybrids, gensets, locomotives, and in marine markets.
The goal of this research project was to develop and demonstrate NEA membranes having twice the improvement in productivity on off-road diesel engines. This improvement will be realized through higher flux membranes, improved membrane packaging, and optimized air separation. Good progress already has been made toward this target. A 30 percent improvement was demonstrated in recently manufactured products by CMS’ partner, Innovative Membrane Systems, Inc. (IMS), through higher flux fibers and increased membrane area packing in the cartridge.
Introduction of nanoparticles in the CMS membrane-separating layer on the hollow fibers has been targeted as a method for substantially improving the membrane’s flux. Research during Phase I has confirmed that selected nanoparticles have potential for twice the improvement. Incorporating either silicon dioxide or titanium dioxide nanoparticles in the 8 to 21 nanometer size as a filler in the CMS-3 polymer proved effective in increasing the permeation flux of cast flat sheet membranes used in the screening research. As little as 20 percent by volume of these fillers doubled the improvement in membrane permeability. Translation of this to the coating on the hollow fiber will be carried out in Phase II.
Conclusions:
The hydraulic and separation efficiency of the current membrane cartridge was investigated extensively during this research project in an effort to explain why air separation in the cartridges has an oxygen-nitrogen selectivity of 2.3 versus 2.6 for the polymer. Studies of fiber packing, shell-side residence time distributions, and the profile of NEA composition across the NEA product tubesheet all indicate substantial departures from plug flow on the shell side of the device. Premature breakthrough in the residence time distribution provides evidence that low-resistance paths exist on the shell side. These detract from the air separation efficiency and suggest that much of the expected benefit of air-swept membranes (one method being considered for flux improvement) will be lost unless the design is improved. As a result of this work, CMS now has proven tools for evaluating alternative cartridge designs.
Praxair, Inc., and their subsidiary IMS of Norwood, MA, have been collaborators with CMS and Caterpillar in the NEA membrane area since 2001. In July 2004, Membrane Systems DuPont Air Liquide (MEDAL), the membrane arm of Air Liquide, acquired the assets and technology of IMS. MEDAL has expressed interest in supplying the NEA membranes to the program, but has declined acquisition of IMS’ license with Caterpillar and the global, exclusive agreement with CMS. The transition of IMS to MEDAL during this Phase I research project necessitated numerous changes from the proposed program, resulting in a major setback in CMS’ commercialization plans and progress on this research project. CMS is actively researching its options for developing MEDAL or other organizations as partners, collaborators, and product suppliers in this market.
Supplemental Keywords:
membrane, off-road diesel engine, NOx, emissions, nitrogen-enriched air, NEA, flux fibers, silicon dioxide, titanium dioxide, polymer, SBIR,, Scientific Discipline, Air, TREATMENT/CONTROL, POLLUTANTS/TOXICS, Chemical Engineering, air toxics, Air Pollutants, Pollution Control, Chemistry, mobile sources, Engineering, Chemistry, & Physics, exhaust gas recirculation, criteria air pollutants, Nitrogen Oxides, Nox, electrochemical technology, Nitrogen dioxide, emission control technologies, vehicle emissions, pollution control technologies, trucks and buses, automotive exhaust, automobiles, carbon monoxide, Nitric oxide, diesel, nitrogen oxides (Nox), cost effectiveThe 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.