Laboratory Analysis Of Catalytic Converters Leads To Better - Inece

LABORATORY ANALYSIS OF CATALYTIC CONVERTERS LEADS TO BETTER
ENFORCEMENT RESULTS
SMITH, DON 1 , SUGGS, JENNIFER 2 , ISIN, AMELIE 3
1 Chemist, National Enforcement Investigations Center, Office of Criminal Enforcement,
Forensics and Training, Office of Enforcement and Compliance Assurance, U.S. Environmental
Protection Agency, smith.donj@epa.gov
2 Chemist, National Enforcement Investigations Center, Office of Criminal Enforcement,
Forensics and Training, Office of Enforcement and Compliance Assurance, U.S. Environmental
Protection Agency, suggs.jennifer@epa.gov
3 Program Analyst, Air Enforcement Division, Office of Enforcement and Compliance
Assurance, U.S. Environmental Protection Agency, isin.amelie@epa.gov
SUMMARY
EPA’s National Enforcement Investigations Center (NEIC) is a forensic laboratory that
also analyzes catalytic converters to determine the compliance of recreational vehicle and
motorcycle manufacturers with the Clean Air Act. NEIC has developed some innovative
techniques for the measurement of catalyst washcoat loading on motorcycle and recreational
vehicle catalytic converters. The catalytic converters present a challenge because the washcoat is
tightly bound to a metallic substrate and is physically inaccessible. Physical removal of the
washcoat followed by analysis by X-ray fluorescence spectrometry has shown the vast majority
of the sampled catalytic converters to be noncompliant, leading to successful EPA enforcement
actions against recreational vehicle and motorcycle manufacturers and importers.
1 INTRODUCTION AND BACKGROUND
The U.S. Environmental Protection Agency (EPA)’s mission is to protect human health
and the environment, and this includes responsibilities for air emissions from imported vehicles
and engines. The Clean Air Act (CAA) requires imported engines and vehicles to be covered by
an EPA certificate of conformity (COC), demonstrating that they meet emission standards. EPA
takes action when imported goods are not in compliance with the Clean Air Act.
Many of the imported vehicles that have been inspected by EPA are not covered by their
COCs because the catalytic converters have been found to be materially different from the design
specified in the application for the COC. For this reason, EPA concludes that the source vehicles
are uncertified and have been imported in violation of the Clean Air Act. EPA’s Mobile Source
Enforcement Branch has recently been particularly focused on recreational vehicle and
motorcycle cases, given the high rate of noncompliance with CAA requirements in this sector.
Laboratory analysis of catalytic converters is critical for EPA enforcement and helps the
EPA focus its limited resources on the products that cause the most environmental harm.
Vehicles and engines with noncompliant catalytic converters emit higher levels of carbon
monoxide, hydrocarbons, and nitrogen oxides that contribute to the formation of ground-level
ozone, or smog. Exposure to even low levels of ozone can cause respiratory problems, and
repeated exposure can aggravate pre-existing respiratory diseases. In addition, air toxics such as
hydrocarbons are known or suspected human carcinogens.
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Motorcycle and recreational vehicle catalytic converter specifications include the volume
of the catalytic converter, the amount of each catalytic metal present, and the number of pores in
the converter. The most common catalysts used for pollution control contain metals or metal
oxides such as platinum (Pt), palladium (Pd), rhodium (Rh) and vanadium pentoxide (V 2 O 5 ).
These catalysts increase the rate at which the incomplete combustion products of carbon
monoxide, hydrocarbons, and nitrogen oxides are converted to carbon dioxide, water vapor, and
nitrogen. Catalysts provide a reaction site for the molecules and decrease the reaction energy
needed to convert the molecules. These metals are mixed with a carrier, such as aluminum
oxide, and then deposited on a support that can be either ceramic (automotive catalytic
converters) or metal (recreational vehicle or motorcycle catalytic converters). A typical
recreational vehicle or motorcycle exhaust catalytic converter consists of a metallic substrate that
is coated with an active layer of the carrier, or washcoat. In production, washcoat loading is
normally determined by a weight gain procedure.
When EPA began its laboratory analysis of catalytic converters in 2008, the agency
lacked an established procedure for analysis of recreational vehicle or motorcycle exhaust
catalytic converters. EPA refined its sample preparation and X-ray fluorescence spectrometry
(XRF) analysis methodology through trial and error. Refinements simultaneously improved the
accuracy of results and reduced the time necessary to obtain results, improving the effectiveness
of EPA’s enforcement response. This paper provides a detailed description of the laboratory
techniques EPA is using and the enforcement results EPA has achieved for recreational vehicles
and motorcycles based on its catalytic converter analysis work.
2 SAMPLING
EPA has, to date, examined catalytic converters from vehicles and engines that were built
by more than 18 different manufacturers. Samples are obtained through inspections conducted at
retail locations and at U.S. ports. The U.S. Department of Homeland Security’s Bureau of
Customs and Border Protection (CBP) conducts the portside inspections. Officers identify
shipments with particular focus on companies that have previously violated the Clean Air Act,
and put them on hold for inspection. EPA investigators, working closely with a special team of
CBP officers, then inspect the vehicles and engines. If the vehicles or engines are certified with
a catalytic converter, EPA removes the muffler. The catalytic converter samples are then
removed from the vehicle muffler, but are left uncut in their original sleeve for mailing to EPA’s
National Enforcement Investigations Center (NEIC) under chain of custody for analysis.
3 SAMPLE PREPARATION AND PHYSICAL MEASUREMENTS
NEIC initially assumed that the internal structure of the motorcycle and recreational
vehicle catalytic converters would contain ceramic substrates similar to that of automotive
catalytic converters.
However, examination of the actual mufflers from motorcycle and recreational vehicles
showed they contained a stainless steel honeycomb mesh coated with the washcoat.
Manufacturers produce the honeycomb from corrugated stainless steel rolled into a cylinder and
encased in a steel tube (Figure 1).
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FIGURE 1. End View of a Recreational Vehicle or Motorcycle Catalytic Converter
Because of this unique configuration, NEIC developed two different strategies to remove
the washcoat. NEIC developed the first strategy from a catalytic converter manufacturer that
employed a wash procedure using acid and hydrogen peroxide. In this procedure, large volumes
of solution containing nitric acid and hydrogen peroxide removed the washcoat containing the
precious metals platinum, palladium, and rhodium. The resulting solution was then treated with
hydrochloric acid and evaporated to dryness. After several cycles of treatment, the residue was
heated to 540 degrees Celsius (°C) in a muffle furnace, then ground. NEIC analyzed the ground
material for the precious metal concentrations.
NEIC’s examination of the stainless steel mesh after the acid and peroxide extractions
revealed that a residue of washcoat remained on the honeycomb mesh. Physical manipulation of
this mesh yielded additional material, indicating incomplete removal of the washcoat. This led
NEIC to develop a procedure to physically remove the washcoat from the catalytic converters.
Physical measurements, photographs, and weights were required to ascertain the
specifications for the catalytic converters. Metric calipers and rulers were used to measure the
height and diameter of the stainless steel mesh and outer pipe. These measurements were used to
calculate the area of the mesh monolith and determine the volume of the cylinder. Photographs
of the ends of the mesh were taken for pore count measurement. Initial, periodic, and final
weights of the samples and separate parts of the samples (outer casing, honeycomb mesh, and
washcoat recovered) were recorded during disassembly.
After the initial weight was recorded, NEIC used an angle grinder with a metal cutting
wheel to cut through the outer casing of the catalytic converter (Figure 2).
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FIGURE 2. Analyst Cutting the Outer Steel Casing of a Catalytic Converter
After the initial cut, NEIC removed the outer pipe to expose the stainless steel mesh that
contained the aluminum oxide based washcoat. In many samples, the stainless steel mesh was
manually unwound to remove the washcoat. Unwinding the mesh removed a significant amount
of washcoat material, which was collected, weighed, and stored. The physical removal was
continued until no additional washcoat could be removed.
In some other samples, the fabrication of the honeycomb mesh prevented the mesh from
unwinding. These samples required disassembly with additional force and also additional care to
ensure minimal loss of washcoat.
To disassemble these more challenging samples, NEIC placed the tip of an awl into a
mesh hole and tapped it with a rubber mallet to break the mesh and release the washcoat. Using
these tools, the mesh was reduced to small metal pieces. Both washcoat and metal pieces were
collected in weigh boats beneath the samples. A magnet was used to remove metallic fragments
from the powder (Figure 3).
NEIC investigated a coarse disassembly method that separated the mesh into large
chunks instead of small strips. If successful, a coarse disassembly could provide a faster method
of disassembly with the same or similar washcoat removal results. After this coarse method was
applied, weights were obtained, then the large chunks were reduced further using the fine
disassembly method. After the samples were completely reduced using the fine disassembly,
weights for the mesh pieces and for the washcoat were taken. A comparison of the weights
indicated that a significant amount of washcoat still remained in the mesh after the coarse
disassembly method. The more intensive and time-consuming fine disassembly proved to be the
better method for removal of the washcoat.
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FIGURE 3. Removal of Metallic Debris Using a Magnet
4 XRF ANALYSIS
NEIC selected XRF to analyze the precious metal content of the catalytic converter
washcoat. This technique uses an X-ray source to remove inner shell electrons of the atoms in a
sample which in turn are replaced by outer shell electrons. The resulting change in energy
causes the atoms to emit X-rays that are characteristic of that element. The emitted X-rays are
measured quantitatively by calibrating the instrument with standards containing known
concentrations of the elements of interest. XRF was chosen because it is relatively fast, has very
high precision, and does not require dissolution of the sample. However, since XRF is a direct
measurement analytical tool, sample preparation is critical. The success of the technique
depends on how similar the samples are to the calibration standards, both in physical form and in
chemical makeup.
Washcoat removal frequently yields masses that are too low to utilize standard XRF
pressed powder sample preparation techniques. To provide a consistent, stable sample for XRF
analysis, the samples are diluted in reagent grade aluminum oxide and a cellulose binder. This
mixture of washcoat, aluminum oxide, and cellulose binder is ground with an agate mortar and
pestle or using a ball mill and then pressed into a pellet that can be analyzed by XRF. The XRF
spectrometer is calibrated using a combination of National Institute of Standards and Technology
(NIST) standard reference materials (SRMs) and synthetically prepared standards containing
platinum, palladium, and rhodium. Variations in the sample matrix are partially corrected
through the use of a Compton scattering correction.
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5 RESULTS
EPA’s enforcement efforts are constantly evolving to keep pace with the changing
compliance landscape. Currently, EPA is addressing the growing number of recreational vehicle
and motorcycle imports from China. To date, almost all of the catalytic converters sampled from
these vehicles and sent to the laboratory for analysis have been found to be noncompliant. This
may, in part, be due to the rising costs of the precious metals which are critical to catalytic
converter efficacy.
In 2010, EPA and CBP stopped a total of about 14,000 recreational vehicles, small
gasoline-powered engines, and motorcycles at the port because they were not built to the correct
certified design. In almost all instances, these vehicles and engines bore labels stating they were
certified. EPA inspections, however, found that approximately 80% of the vehicles and engines
differed from the certified design in ways that could affect emissions, with about half of the
uncertified vehicles and engines having nonconforming catalytic converters.
In addition to seizures at the ports, EPA’s inspections and analysis work has culminated
in several case settlements, the largest of which was against The Pep Boys – Manny, Moe & Jack
(Pep Boys) and Baja, Inc. (Baja) in May 2010. Pep Boys is a national automotive aftermarket
and service chain that operates more than 580 stores in 35 states and Puerto Rico. Baja contracts
with manufacturers in the People’s Republic of China to supply recreational vehicles and
motorcycles to Pep Boys and other U.S. companies. Baja also handles all after-sale functions,
such as warranty claims and replacement parts. This case was the largest vehicle and engine
importation case brought under the CAA by the U.S. by number of vehicles and engines affected
and penalty paid. The case involved the importation of at least 241,000 illegal vehicles and
engines over a six year period, and resulted in a $5 million civil penalty. At its peak, Pep Boys
was the third largest importer of Chinese-made all-terrain vehicles in the U.S. All of the
catalytic converters analyzed in support of the Pep Boys case were found to be noncompliant.
In June 2010, EPA settled another imports case against Taotao USA, Inc. (Taotao)
involving noncompliant catalytic converters. Taotao and its predecessor, AIMX Industry, Inc.,
d.b.a./a.k.a. AIM-EX Industry, Inc., or Vicoo Industry, Inc, imported thousands of illegal
recreational vehicles into the U.S. between 2008 and 2010. In addition, Taotao was the largest
importer last year of Chinese-made all-terrain vehicles in the U.S. The settlement required
Taotao to pay a $260,000 penalty and implement a rigorous corporate compliance plan,
including regular catalytic converter testing.
On-road and off-road vehicles and engines emit roughly half of the U.S. air pollution.
Importing vehicles and engines without proper emission controls is not only detrimental to
human health and the environment; it also provides an unfair competitive advantage to the
manufacturers of noncompliant products. To address the myriad and expanding number of ways
in which vehicles and engines can be noncompliant, EPA will continue to innovate and explore
new laboratory procedures in support of enforcement cases to ensure that products imported and
sold in the U.S. comply with the Clean Air Act.
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6 BIBLIOGRAPHY
EPA FACTSHEET: Air Toxics from Motor Vehicles, U.S. Environmental Protection Agency,
available at http://www.epa.gov/oms/f02004.pdf.
Heck, R. M., Farrauto, R. J., and Gulati, S. T., Catalytic Air Pollution Control: Commercial
Technology, 2 nd ed., 2002, pp. 3-24, 69-73.
The Pep Boys Manny, Moe & Jack and Baja, Inc. Settlement, U.S. Environmental Protection
Agency, available at http://epa.gov/compliance/resources/cases/civil/caa/pepboys.html.
US EPA Clean Air Act Mobile Source Importation Settlement Information, U.S. Environmental
Protection Agency, available at http://cfpub.epa.gov/compliance/civil/programs/caa/importation/.
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