Method for using hydroxyl radical to reduce pollutants in the exhaust gases from the combustion of a fuel

A method and apparatus are provided for reducing pollutants in the exhaust gases produced from the combustion of a fuel by introducing hydroxyl and associated radicals and oxidizers into at least one of the precombustion and postcombustion gas stream of the combustion engine upstream of the catalytic converter and treating the exhaust gases with the catalytic converter.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention generally relates to a method and apparatus for 
reducing pollutants in the exhaust gases produced by the combustion of 
fuels. More particularly, the invention relates to such a method and 
apparatus wherein the reduction in pollutants is achieved by introducing 
hydroxyl radicals "OH" and other free radical intermediaries and oxidizers 
such as O, H, HO.sub.2 and H.sub.2 O.sub.2 into the precombustion or 
postcombustion gas stream of a combustion engine. 
2. Background 
As is well-known in the art, an internal combustion engine draws in ambient 
air which is mixed with fuel for combustion in a combustion chamber or 
cylinder and the resulting exhaust gases are expelled. Ignition of the 
air/fuel mixture in the cylinder is typically achieved by an ignition 
device, such as, for example, a spark plug or the like, or adiabatic 
compression to a temperature above the fuel's ignition point. 
In certain internal combustion engines, such as for example, gasoline 
engines commonly in use today, air is inducted via an air intake duct or 
port which conveys the ambient air to a carburetor or a fuel injection 
arrangement where the air is mixed with fuel to create an air/fuel 
mixture. The air/fuel mixture is then conveyed via an intake manifold to 
the combustion chamber or cylinder of the engine. In diesel-type engines 
and engines using fuel-injection arrangements, the air and fuel are 
conveyed separately to the combustion chamber or cylinder of the engine 
where they are mixed. 
After the air/fuel mixture has been burnt, the resulting exhaust gases are 
expelled from the combustion chamber to an exhaust manifold. The exhaust 
gases then may be conveyed by an exhaust pipe to the catalytic converter 
where pollutants are removed. 
The flow of air to the combustion chamber, including the flow of the 
air/fuel mixture if applicable, as used herein is referred to as the 
precombustion gas stream, and the resulting flow of exhaust therefrom is 
hereinafter referred to as the postcombustion or exhaust gas stream. As 
used herein, the precombustion and postcombustion gas streams are 
collectively referred to as the combustion gas stream. 
Internal combustion engines which operate by the controlled combustion of 
fuels produce exhaust gases containing complete combustion products of 
carbon dioxide (CO.sub.2) and water (H.sub.2 O) and also pollutants from 
incomplete combustion such as carbon monoxide (CO), which is a direct 
poison to human life, as well as unburnt hydrocarbons (HC). Further, due 
to the very high temperatures produced by the burning of the hydrocarbon 
fuels followed by rapid cooling, thermal fixation of nitrogen in the air 
results in the detrimental formation of Nitrogen Oxides (NO.sub.x), an 
additional pollutant. 
The quantity of pollutants varies with many operating conditions of the 
engine but is influenced predominantly by the air-to-fuel ratio in the 
combustion cylinder such that conditions conducive to reducing carbon 
monoxide and unburnt hydrocarbons (a fuel mixture just lean of 
stoichiometric and high combustion temperatures) cause an increased 
formation of NO.sub.x, and conditions conducive to reducing the formation 
of NO.sub.x (fuel rich or fuel lean mixtures and low combustion 
temperatures) cause an increase in carbon monoxide and unburnt 
hydrocarbons in the exhaust gases of the engine. Because in modern day 
catalytic converters NO.sub.x reduction is most effective in the absence 
of oxygen, while the abatement of CO and HC requires oxygen, preventing 
the production of these emissions requires that the engine be operated 
close to the stoichiometric air-to-fuel ratio because under these 
conditions the use of three-way catalysts (TWC) are possible, i.e., all 
three pollutants can be reduced simultaneously. Nevertheless, during 
operation of the internal combustion engine, an environmentally 
significant amount of CO, HC and NO.sub.x is emitted into the atmosphere. 
Although the presence of pollutants in the exhaust gases of internal 
combustion engines has been recognized since 1901, the need to control 
internal combustion engine emissions in the United States came with the 
passage of the Clean Air Act in 1970. Engine manufacturers have explored a 
wide variety of technologies to meet the requirements of this Act. 
Catalysis has proven to be the most effective passive system. 
Automotive manufacturers have generally employed catalytic converters to 
perform catalysis. The purpose is to oxidize CO and HC to CO.sub.2 and 
H.sub.2 O and reduce NO/NO.sub.2 to N.sub.2. Auto emission catalytic 
converters are typically located at the underbody of the automobile and 
are situated in the exhaust gas stream of the engine, just before the 
muffler, which is an extremely hostile environment due to the extremes of 
temperature as well as the structural and vibrational loads encountered 
under driving conditions. 
Nearly all auto emission catalytic converters are housed in honeycomb 
monolithic structures with excellent strength and crack-resistance under 
thermal shock. The honeycomb construction and the geometries chosen 
provide a relatively low pressure drop and a high geometric surface area 
which enhances the mass transfer controlled reactions. The honeycomb is 
set in a steel container and protected from vibration by a resilient 
matting. 
An adherent washcoat, generally made of stabilized gamma alumina into which 
the catalytic components are incorporated, is deposited on the walls of 
the honeycomb. TWC technology for simultaneously converting all three 
pollutants comprises the use of precious or noble metals Pt and Rh, with 
Rh being most responsible for the reduction of NO.sub.x, although it also 
contributes to CO oxidation along with Pt. Recently less expensive Pd has 
been substituted for or used in combination with Pt and Rh. The active 
catalyst is generally about 0.1 to 0.15% precious or noble metals, 
primarily platinum (Pt), palladium (Pd) or rhodium (Rh). 
Because the exhaust gases of the combustion engine oscillate from slightly 
rich to slightly lean, an oxygen storage medium is added to the washcoat 
which adsorbs (stores) oxygen during any lean portion of the cycle and 
releases it to react with excess CO and HC during any rich portion. Cerium 
Oxide (CeO.sub.2) is most frequently used for this purpose due to its 
desirable reduction-oxidation response. 
The recent passage of the 1990 amendment to the Clean Air Act requires 
further significant reductions in the amount of pollutants being released 
into the atmosphere by internal combustion engines. In order to comply 
with these requirements, restrictions on the use of automobiles and trucks 
have been proposed, such as, employer-compelled car pooling, HOV lanes, 
increased use of mass transit as well as rail lines and similar actions 
limiting automobile and truck usage at considerable cost and 
inconvenience. 
An alternative to diminished automobile and truck usage is decreasing 
emissions by increasing the efficiency of the internal combustion engine. 
This approach will have limited impact since studies show that most of 
automobile-originated pollution is contributed by only a small fraction of 
the vehicles on the road, these vehicles typically being older models 
having relatively inefficient engines and aging catalytic converters which 
inherently produce a lot of pollution. Any technological improvements to 
the total combustion process will not be implemented on these older 
vehicles if they require extensive or expensive modification to the engine 
or vehicle. 
In addition, while considerable gains have been made in recent years to 
reduce the amount of pollutants in the exhaust gases of the internal 
combustion engine of vehicles such as automobiles and trucks, it is a 
considerable technological challenge and expensive to further reduce the 
amount of pollutants in the exhaust gases of the internal combustion, even 
though exhaust emissions of automobiles and trucks currently being 
manufactured do not meet proposed Environmental Protection Agency 
standards. 
In lieu of decreasing exhaust emissions by increasing the efficiency of the 
internal combustion engine or decreasing the use of automobiles, a further 
alternative would be to increase the efficiency of the catalytic converter 
or catalysis. The conversion efficiency of a catalytic converter is 
measured by the ratio of the rate of mass removal of the particular 
constituent of interest to the mass flow rate of that constituent into the 
catalytic converter. The conversion efficiency of a catalytic converter is 
a function of many parameters including aging, temperature, stoichiometry, 
the presence of any catalyst poisons (such as lead, sulfur, carbon and 
phosphorous), the type of catalyst and the amount of time the exhaust 
gases reside in the catalytic converter. 
Attempts to increase the efficiency of catalytic converters has not been 
sufficiently successful. Modern TWC catalytic converters help, but they 
are expensive, may have difficulty in meeting the future emission 
requirements, and have limitations in their performance lifetime. 
Catalytic converters also suffer from the disadvantage that their 
conversion efficiency is low until the system reaches operating 
temperature. 
SUMMARY OF THE INVENTION 
One object of the present invention is to provide a method and apparatus 
for reducing pollutants in the exhaust gases of an internal combustion 
engine without the need for major modifications to the internal combustion 
engine or the catalytic converter. 
Another object of the invention is to provide a method and apparatus, which 
are inexpensive to employ and manufacture, and simple in structure and 
operation, for reducing pollutants of incomplete combustion in the exhaust 
gases of a combustion engine. 
In accordance with the invention, it is believed that hydroxyl radical "OH" 
and other free radicals and oxidizers such as O, H, HO and H.sub.2 O.sub.2 
can be introduced into the combustion gas stream of a combustion engine to 
reduce pollutants and contaminants such as CO and HC. It has been observed 
that OH in the presence of oxygen can react rapidly with CO to produce 
CO.sub.2. It has also been observed that OH in the presence of oxygen can 
react rapidly with hydrocarbons (HC) to produce formaldehyde or other 
similar intermediary products which then further react with OH to form 
H.sub.2 O, CO.sub.2, and OH. Moreover, there is evidence that the series 
of reactions does not consume, but rather regenerates OH. 
In the case of CO, the following reaction steps convert CO to CO.sub.2 and 
regenerate OH: 
CO + OH .fwdarw. CO.sub.2 + H 
H + O.sub.2 .fwdarw. HO.sub.2 
HO.sub.2 + h.nu. .fwdarw. OH + O The latter process of dissociation of 
hydroperoxyl to hydroxyl can take place either via the absorption of 
ultraviolet ("UV") photon or by thermal decomposition. 
In the case of HC, a typical reaction set may involve the following steps: 
HC + OH .fwdarw. HCHO 
HCHO + OH .fwdarw. H.sub.2 O + HCO 
HCO + O.sub.2 .fwdarw. CO.sub.2 + HO Depending upon the HC species, there 
may be branching reactions and other free radical intermediaries and 
oxidizers such as O, H, HO.sub.2 and H.sub.2 O.sub.2 may be produced and 
either enter into the reactions directly or through the products of other 
reactions such as: 
O + O.sub.2 .fwdarw. O.sub.3, or 
H.sub.2 O.sub.2 + h.nu. .fwdarw. 2OH 
Particularly important in the present invention is that OH is believed to 
be regenerated in the course of the reactions, i.e., it acts as a 
catalyst, and that the reaction sequence proceeds rapidly due to the 
strong nature of the free radical reactions. 
It is believed that the presence of OH, and other free radical 
intermediates and oxidizers such as O, H, H.sub.2 O.sub.2 and HO.sub.2, in 
the exhaust gases of a combustion engine leads, in the presence of 
requisite oxygen, to a very effective catalytic destruction of CO and 
hydrocarbons to non-polluting gas species CO.sub.2 and water vapor. The OH 
and other related free radicals and oxidizers created in the reactions can 
act as a catalyst independent of or in conjunction with the normal 
catalytic function of the precious metal particles (Pt, Pd, Rh and 
combinations thereof) in the catalytic converter. 
It is believed that the injection of OH into the combustion gas stream 
results in rapid catalyzing of CO and HC reactions in the exhaust gas 
stream. The reactivity of OH is believed to cause much of the catalytic 
activity associated with the conversion of CO to CO.sub.2 and hydrocarbon 
to CO.sub.2 and H.sub.2 O to take place in the gas phase and on the large 
surface area of the washcoat surface of the catalytic converter. Thus, 
within a small region near the entrance of the catalytic converter, the 
bulk of the reactions converting CO and HC to CO.sub.2 and H.sub.2 O 
occurs. Because CO and the HC are oxidized in the gas phase and in the 
washcoat of the catalytic converter, with resulting substantial completion 
of the oxidation of CO and HC near the entrance to the catalytic 
converter, the bulk of the precious metal catalytic surface is freed from 
participating in these competing reactions. For example, the converter's 
precious metal sites no longer need to catalyze the less reactive 
hydrocarbon species such as methane, ethane, ethene, benzene and 
formaldehyde. As a result, more effective catalytic activity at the 
precious metal sites can be directed toward reduction of nitrogen oxides 
to nitrogen and other non-polluting gas species. 
It is believed that the action of the hydroxyl can take place over the 
volume of the exhaust gas and the entire surface area of the catalytic 
converter, i.e., over the entire, large area of the washcoat. This makes 
for a much larger, effective pollutant reduction action over the catalytic 
converter operating in the conventional manner. Under this new mode of 
catalytic conversion operation, nitrogen oxide reduction can diminish 
below conventional baselines. Alternatively, less precious metal content, 
or the use of less costly metals or their oxides can be used to reduce the 
nitrogen oxide compounds below allowable emission limits. 
Several different modes of operation and devices may be utilized to carry 
out the invention. In one embodiment, OH is produced in a generator using 
mercury (Hg) vapor lamp radiation and atmospheric air intake which is 
conditioned to be of sufficiently high water vapor content, and preferably 
to about 100% saturation. It is believed that in air of high water vapor 
content there are two alternative competing reaction branches for creating 
OH. In the first case, there is direct photodissociation of the water into 
OH and H by the absorption of 185 nanometer ("nm") photons. To achieve 
such high humidity, the water vapor can come from a heated water source or 
it can be supplied from the exhaust gas stream of the engine. The other 
reaction, which is favored at a lower, but still sufficiently high, water 
vapor content, is that the 185 nm ultraviolet ("UV") radiation from the 
lamp acts on the air to produce atomic oxygen (O) and ozone (O.sub.3). The 
ozone is created by a three-body reaction involving atomic oxygen, 
molecular oxygen and any other molecular constituent of air, such as, for 
example, Nitrogen (N.sub.2), Oxygen (O.sub.2), Water (H.sub.2 O) or Argon. 
The 253.7 nm UV radiation breaks down the ozone by photodissociation into 
molecular oxygen O.sub.2 and a metastable oxygen atom (O). If the air 
stream entering the generator has sufficient water vapor content, then it 
is believed the metastable atomic oxygen (O) combines with water molecules 
to form hydrogen peroxide: 
O + H.sub.2 O .fwdarw. H.sub.2 O.sub.2 Further, the 253.7 nm UV radiation 
photodissociates the hydrogen peroxide into two hydroxyl molecules. 
The generator thus injects ozone, atomic oxygen, hydrogen peroxide, and 
hydroxyl into the engine via for example, the intake manifold. It is 
believed that any hydrogen peroxide so injected will dissociate into 
hydroxyl under the high engine temperature. The hydroxyl which resides in 
the crevice regions of the combustion chamber should survive the 
combustion process in the engine and act upon the CO and HC remaining in 
the exhaust stream to produce CO.sub.2 and H.sub.2 O according to the 
reactions described above. 
A further embodiment of hydroxyl generation is to feed a water vapor-rich 
input air stream into a glow discharge generator (a generator in which a 
glow discharge occurs in water vapor primarily or only). Another approach 
is an overvoltage electrolysis cell to generate ozone in addition to 
oxygen and water vapor, followed by 200-300 nm UV exposure to create 
atomic oxygen by photodecomposition which in the presence of a water 
vapor-rich input air stream initiates hydrogen peroxide creation, followed 
by hydroxyl generation via UV dissociation of the hydrogen peroxide. This 
latter device can be very compact using a mercury vapor lamp as the UV 
source due to the high efficiency of the output at 253.7 nm and the high 
absorbability of ozone and hydrogen peroxide for UV light of this 
wavelength. 
The foregoing embodiments principally involve generators injecting their 
streams of output gases into the intake manifold region of the engines. A 
natural advantage of such methods is that the low pressure condition in 
regions of the intake manifold provides a natural pumping mechanism. 
However, a drawback of these methods is that most of the highly chemically 
active species, including the free radicals such as hydroxyl, are 
destroyed in the combustion process and only those active species in the 
crevice regions and at the walls of the combustion chamber can effectively 
survive and enter into the exhaust gas stream where they are useful in 
oxidizing CO and HC. In contrast, generators which inject hydroxyl radical 
directly into or which create hydroxyl in the exhaust (postcombustion) gas 
stream can more effectively deliver the active species into the exhaust 
stream where CO and HC need to be oxidized. Thus, less chemically active 
species source strength would be required for equivalent emission 
reduction. This should translate directly into proportionally lower 
electrical input demands for the hydroxyl generator. 
However, because of the higher pressures in the exhaust system, pumping is 
required to accomplish direct injection of the generator output into the 
exhaust gas stream. The use of a venturi will assist this process. 
Alternatively, because of the high vapor pressure of water at temperatures 
above approximately 120.degree. C., using a water vapor discharge source 
in the hydroxyl generator can also provide effective injection. Such water 
vapor can be collected by condensation or equivalent means from the 
exhaust system. 
An embodiment creating hydroxyl in the exhaust gas stream is the 
irradiation of the exhaust gas stream with UV radiation in the 120 to 185 
nm wavelength range which in the presence of sufficient water vapor 
produces catalytically active OH by direct photodissociation. A still 
further embodiment is the use of UV radiation in the 120 to 185 nm 
wavelength in an external generator using atmospheric air intake and water 
vapor collected from the exhaust gas stream and injecting water vapor, OH 
and H into the exhaust gas stream prior to or in the catalytic converter. 
The means described above for creation of these free radical species and 
oxidizers include ultraviolet light-based generators, glow discharge 
generators, and overvoltage electrolytic cells plus UV radiation. 
Generator inputs can include electricity, water, air, oxygen, water vapor, 
water vapor plus air and water vapor plus oxygen. 
Modes of possible introduction of the above species into the engine system 
include into the precombustion gas stream, such as the intake manifold, 
into the exhaust gas stream such as the exhaust manifold, and into the 
catalytic converter. The generators can be external or internal to these 
areas. A particularly advantageous feature of the external generator is 
that it provides the flexibility of installing the generator at a 
convenient location in the engine compartment or elsewhere on the vehicle. 
Another advantageous feature of the external generator embodiment is that 
the hydroxyl could be introduced at almost any desirable point in the 
intake or exhaust gas streams of the engine. A further advantageous 
feature of this embodiment is that the flow rate of hydroxyl from the 
hydroxyl generator is independent of engine speed, i.e., flow of air to 
the combustion chamber or flow of exhaust gases from the combustion 
chamber. Thus, at low engine speeds, the mass flow rate of hydroxyl will 
not be affected by low air mass flow through the combustion chamber. For 
external sources, means of pumping of the generator gas products can 
include natural low pressure areas in the engine, introduction of ventri 
regions, external pumps, or natural generator pressurization as with 
higher temperatures and water vapor sources. 
Thus, the invention employs hydroxyl and its associated reaction species, 
O, H, H.sub.2 O.sub.2 and HO.sub.2 to provide a catalytic cycle with OH 
playing the central role in reducing the CO and HC outputs of engines to 
meet present and future Ultra Low Emissions Vehicle "ULEV" and Low 
Emissions Vehicle "LEV" standards. Because the OH acts as a catalyst, 
relatively small amounts of OH need to be injected for orders of magnitude 
more CO and hydrocarbons to be reduced to CO.sub.2 and H.sub.2 O in the 
presence of oxygen in the exhaust gas stream. 
An advantageous feature of the invention is that reduced emissions are 
achieved by adding hydroxyl radicals and other free radical intermediaries 
and oxidizers such as O, H, HO.sub.2 and H.sub.2 O.sub.2 to modify the 
composition of the exhaust gases without the need to store special 
chemical additives onboard. 
Yet another advantageous feature of the invention is that it can be applied 
to a variety of different types of engines including gas turbine and 
internal combustion engines, including, but not limited to, automobiles, 
trucks, stationary power generators, motorboats, motorcycles, motorbikes, 
lawn mowers, chain saws or leaf blowers which may use a variety of 
different fuels such as gasoline, gasoline-based formulations, diesel 
fuel, alcohol, natural gas and any other fuel where it is desired to 
reduce CO or HC. 
It is believed that a further advantageous feature of the present invention 
is that due to the introduction of gas-phase catalyst species, whose 
activities occur over the whole catalytic converter surface, and the 
inherent reactivity of these species, much earlier catalytic conversion of 
CO and unburned HC will occur after engine start. In other words, the 
effective light-off delay time after engine start will be reduced as 
compared to the use of a typical catalytic converter. 
In the case of combustion and other residential, commercial and industrial 
systems which have exhaust gas streams which contain volatile organic 
compounds (VOCs), but contain minimal or no nitrogen oxides such as from 
some industrial processes, there would be no need for the typical 
catalytic converter and certainly no need for a precious metal catalytic 
converter. This invention would provide for very low cost catalytic 
converter systems. In those situations where only CO or HC and other VOC's 
are required to be oxidized, it is contemplated that a typical catalytic 
converter would not be required. However, it is contemplated that adequate 
time and/or a large surface area similar to that provided by the honeycomb 
structure of the typical catalytic converter would be necessary to allow 
the CO, HC and VOC oxidation reactions to take place. 
These and other objects, advantages and features of the invention are 
achieved, according to one embodiment, by an apparatus comprising: 1) a 
combustion gas stream of an engine, 2) a catalytic converter for treating 
the exhaust gases in the combustion gas stream to reduce further the 
amount of at least one pollutant from incomplete combustion of fuel and/or 
oxides of nitrogen, and 3) a device for adding OH and associated free 
radicals and oxidizers to the combustion gas stream upstream from or at 
the catalytic converter to reduce further the amount of at least one 
pollutant in exhaust gases treated by the catalytic converter. 
In accordance with the invention, a method is provided for treating exhaust 
gases to reduce at least one pollutant from incomplete combustion of a 
fuel having a precombustion gas stream of at least ambient air to the 
combustion chamber and a postcombustion gas stream of exhaust gases from 
the combustion chamber, the method comprising the steps of: adding 
hydroxyl and associated free radicals and oxidizers to at least one of the 
precombustion and the postcombustion gas streams and providing sufficient 
surface area in the postcombustion gas stream to allow the hydroxyl to 
treat the exhaust gases produced from the combustion of the fuel to at 
least reduce one pollutant from combustion.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S) 
Referring to FIG. 1, a known configuration of an automobile engine 11 
having a catalytic converter 13 is illustrated. The catalytic converter 13 
is positioned at the underbody of the automobile (not shown) and is 
situated in the exhaust gas stream A from the engine, downstream from the 
exhaust manifold 15 and just before the muffler 17. 
The catalytic converter 13, as contemplated for use in the present 
invention, includes any device which is provided for treating exhaust 
gases from the combustion of a fuel, such as, for example, gasoline, 
gasoline-based formulations, diesel fuel, alcohol, natural gas and any 
other fuel where a catalytic converter can be used to reduce at least one 
pollutant from combustion, such as, for example, CO, and unburnt HC, 
and/or NO.sub.x, including, but not limited to, a three way catalyst 
typically used in today's modern automobile engines. 
The catalytic converter 13 therefore comprises any device that 
catalytically removes or participants in the removal of at least one 
pollutant from an exhaust stream generated by burning a fuel, including, 
but not limited to, those with monolithic or granular ceramic substrates, 
metallic substrates, or substrates of any kind, and devices with noble 
metals or any other type of catalytic material. It would also include, 
without limitation, devices having semiconductor catalysts such as oxides 
or sulphides of transition elements, and devices having ceramic-type 
catalysts, such as alumina, silica-alumina, and zeolites individually, in 
combination with each other and oxygen storage media such as cerium oxide 
or in combination with metal catalysts. 
Referring to FIG. 2, one embodiment of an apparatus of the invention is 
illustrated generally at 19. The apparatus 19 comprises a generator 20 for 
generating hydroxyl. In one embodiment, generator 20 has an UV 
light-emitting lamp 21, for example, a mercury vapor arc lamp emitting at 
about 185 and about 254 nanometers. The lamp has a light-transmitting 
envelope for transmitting UV light having wavelengths of about 100-300 nm, 
because this emission, in the presence of sufficient water vapor content, 
is capable of producing hydroxyl from air. The light transmitting envelope 
may be fused silica, or its equivalent synthetic quartz, supersil, 
sapphire or any other material capable of transmitting ultraviolet light 
having a wavelength down to about 100 nanometers, and preferably to at 
least 185 nanometers. Other UV generating lamps such as those containing 
Neon, Argon and combinations of these and other gases may be used. 
The lamp 21 is excited by a power supply 23 capable of providing an initial 
electric break down of the gas within the lamp and further providing a 
sustaining voltage for the lamp radiant output. The lamp radiant output 
can be further controlled as needed by varying the lamp current. The power 
supply 23 is directly connected to the electrical system 25 of the 
automobile by splicing into the hot wire (not shown) of the system, for 
example, as original equipment on a new vehicle. Alternatively, the power 
supply 23 is connected to the electrical system 25 by using a plug adapted 
to be inserted into a cigarette lighter receptacle in the passenger 
compartment of the vehicle. 
It is important in this embodiment for effective generation of hydroxyl 
that sufficient water vapor, and preferably about 100% saturated air, be 
present in the hydroxyl generator 20 utilizing the UV lamp 21 as the means 
to generate the hydroxyl. This water vapor may be delivered to the 
generator 20 via water vapor inlet passage 65. Water vapor may be supplied 
to inlet passage 65 by any number of alternative or combination of methods 
including heating water supplied from a stored bottle of water as 
described and illustrated with reference to FIG. 5. Alternatively, water 
vapor may be separated from the exhaust gas stream A as illustrated in 
FIG. 4 at an exhaust gas separator 43 and either directly supplied to 
inlet passage 65 without being collected in a water storage container, or 
alternatively through a storage container. Alternatively, water vapor from 
the exhaust gas stream can be condensed and stored in a container, and 
thereafter heated to form water vapor. In yet an additional alternative 
embodiment the exhaust gases may be supplied directly to the hydroxyl 
generator. As an additional alternative embodiment, the air introduced 
into the hydroxyl generator can be bubbled through water as described and 
illustrated with reference to FIG. 5. This water can be supplied from an 
external source or may be condensed from the water vapor present in the 
exhaust gas stream. 
It is contemplated that air of sufficiently high water vapor content, and 
preferable about 100% saturated, passing through the generator 20 as 
provided by the embodiment of FIG. 2 will result in direct 
photodisassociation of the water into OH and H by the adsorption of 
approximately 100-185 nm photons. Alternatively, the 100-185 nm UV 
radiation from lamp 21 acts on the air to produce ozone and atomic oxygen. 
The 253.7 nm UV radiation breaks down the ozone by photodissociation into 
molecular oxygen and a metastable oxygen atom. The metastable oxygen 
combines with the water molecules present to form hydrogen peroxide which 
photodissociates in the presence of the 253.7 nm UV radiation into two 
hydroxyl molecules. 
In the apparatus 19 as illustrated by FIG. 2, the lamp 21 is positioned 
upstream from the engine's carburetor or fuel injection system, generally 
indicated at 31 in FIG. 1, for example, between an air filter 27 and air 
intake duct 29. However, the present invention additionally contemplates 
positioning the generator 20 anywhere along the precombustion gas stream. 
In order to increase the effective absorption coefficient of the oxygen in 
the air being inducted into the engine 11, the walls adjacent to the lamp 
21 are provided with a surface highly reflective to ultraviolet light in 
the required wavelength range, for example, made of aluminum, in order to 
increase the mean free path of the ultraviolet light, since aluminum 
maintains its reflectance to ultraviolet light down to at least 185 nm. 
According to the teaching of the present invention, it is possible to also 
place the hydroxyl generator 20 downstream from the engine's carburetor or 
fuel injection system 31 and prior to the combustion chamber, for example, 
in the intake manifold 35 as best seen in FIG. 3. 
Referring to FIG. 4, a further embodiment of the invention is illustrated 
wherein the generator 20 is positioned remotely from the precombustion and 
postcombustion gas streams, and hydroxyl-enriched air, with other free 
radical intermediaries and oxidizers, is piped into the combustion gas 
stream. In this embodiment, hydroxyl generator 20 for generating hydroxyl 
from air, draws in ambient air independently of the operation of the 
engine, for example, using a pumping mechanism 39. The ambient air is 
mixed with water vapor in the generator 20 or water vapor is added to the 
ambient air before entering the generator and the high water vapor content 
air, preferably 100% saturated, is converted to hydroxyl-enriched air by 
exposure, for example, to UV light or by means of a corona or glow 
discharge device, and added to at least one of the precombustion or 
postcombustion gas streams in accordance with the teachings of the 
invention. 
Water vapor container 50 delivers water vapor to generator 20 to insure 
that the ambient air has sufficient water vapor content, and preferably 
100% saturated. The water vapor container 50 may be a storage bottle which 
contains water in any physical form, i.e., as a solid, liquid, gas or as 
water vapor. The water can be collected from the exhaust gases of the 
engine which produces water vapor as a result of combustion or it can be 
stored from an external source. If water vapor container 50 is liquid 
water, it can be converted to water vapor using any of the well-known 
methods such as heating in the presence of a gas such as air, or air can 
be bubbled through the water to achieve the water vapor input. The water 
vapor and air supplied to the generator 20 can be a single input into the 
generator wherein water or water vapor is added to the air input supplied 
to the generator, this embodiment being illustrated by dashed line 51 in 
FIG. 4. It should be noted that water container 50 is not necessary and 
that water vapor can be separated from the exhaust gas stream in a water 
vapor separator 43 and added directly to the generator or the air inlet. 
Alternatively, exhaust gas can be added directly to either the generator 
or the air and/or gas supplied to the generator. 
A mixing device 41 can be used to enhance mixing of the hydroxyl-enriched 
air with the combustion gas stream. It should be noted that in lieu of 
pumping mechanism 39, ambient air can be drawn in using the vacuum 
generated by the engine 11. Where the hydroxyl enriched air is introduced 
into the exhaust gas stream, a venturi 55 may be necessary. 
FIG. 5 illustrates a hydroxyl generator 20 which may be utilized in the 
system shown in FIG. 4. Hydroxyl generator 20' has a mercury vapor lamp 21 
which is connected to a power supply 60. The mercury vapor lamp 21 
transmits ultraviolet light having a wavelength of 100-300 nm because this 
emission in the presence of sufficient water vapor content is capable of 
producing the needed amount of hydroxyl from air. 
Air inlet canister 62 has a screen and an air filter (not shown) and 
supplies air to hydroxyl generator 20'. Air inlet passageway or pipe 64 
delivers the air from the inlet canister 62 to the generator 20'. Air 
inlet passageway 64 may contain a pump (not shown) to facilitate the 
delivery of air to hydroxyl generator 20. It is important for effective 
generation of hydroxyl that sufficient water vapor, and preferably 100% 
saturated air, be present in the hydroxyl generator utilizing the UV lamp 
21 as the means to generate the hydroxyl. This water vapor may be 
delivered to the generator 20' via water vapor inlet passage 65'. Water 
vapor inlet passage 65' can collect the water vapor from the exhaust gas 
stream A via passageway E utilizing water vapor separator 43 as shown in 
FIG. 4, or any of the other alternative methods described herein. In FIG. 
5, the water vapor is supplied by heated water source 68. Heated water 
source 68 is an external supply of water which is circulated through the 
engine via circulation pipes 69 in order to heat the water supply. The 
water is preferably heated to or maintained at a temperature that is equal 
to or less than the temperature within the hydroxyl generator. Water vapor 
is drawn from heated water source 68 and delivered via water vapor inlet 
passage 65' into the hydroxyl generator 20'. 
Alternatively, water vapor inlet 65 can connect to air inlet pipe 64 and 
both the air and water vapor can be mixed and then delivered to the 
hydroxyl generator 20'. Water vapor can be collected from the exhaust gas 
stream or the heated water source system 68, 69 can be used to supply the 
water vapor to water vapor inlet 65 or the alternative methods described 
herein can be utilized. 
A further alternative embodiment for delivering sufficient water vapor to 
the hydroxyl generator 20' also is shown in FIG. 5. In this embodiment, 
water is delivered to and collected in a storage container 63 via water 
inlet 65. Air from air inlet canister 62 is bubbled through the water to 
achieve sufficient water content or humidity. The water collected in 
storage container 63 can be from an external source or water vapor or 
water from the exhaust gas stream can be condensed. 
The inside surface of the hydroxyl generator 20' is provided with a surface 
highly reflective to ultraviolet light in the required range such as 
aluminum which maintains its reflectance to ultraviolet light down to at 
least 185 nm. 
It is believed that air of sufficient water vapor content, as supplied by 
the embodiment of FIG. 5, passing through the generator 20 will result in 
direct photodisassociation of the water into OH and H by the adsorption of 
185 nm photons. Alternatively, the 185 nm UV radiation from lamp 21 acts 
on the air to produce ozone and atomic oxygen. The 253.7 nm UV radiation 
breaks down the ozone by photodissociation into molecular oxygen and a 
metastable oxygen atom. The metastable oxygen combines with the water 
molecules present to form hydrogen peroxide which photodissociates in the 
presence of the 253.7 nm UV radiation into two hydroxyl molecules. 
The hydroxyl, as well as any of the free radicals and oxidizers H, O, 
HO.sub.2, H.sub.2 O.sub.2, generated by the hydroxyl generator 20' is 
delivered via the generator outlet 70 to the combustion gas stream. The 
generator output may be added to the precombustion or postcombustion gas 
streams. If the generator output is delivered to the postcombustion gas 
stream, it is anticipated that less hydroxyl output would be required for 
the same level of performance than if it was added to the precombustion 
gas stream because much of the hydroxyl, and the other free radicals and 
oxidizers, added to the precombustion gas stream would not survive the 
combustion process. The hydroxyl which survives combustion or which is 
delivered to the postcombustion gas stream acts upon the CO and HC in the 
exhaust stream to produce non-polluting CO.sub.2 and H.sub.2 O. 
A further hydroxyl generator 20" is shown in FIG. 6. Air having sufficient 
water vapor is delivered to corona or glow discharge generator 20" and may 
be accomplished in the same manner and according to the same alternative 
or combination of embodiments described herein and especially when 
referring to FIGS. 2, 4 and 5. Generator 20" has an outer electrode 81 
with an inner electrode 83. A dielectric coating or material 82 is 
inserted between outer electrode 81 and inner electrode 83. One lead from 
a high voltage, high frequency power supply is connected to the inner 
electrode 83 while the other lead is connected to the outer electrode 81. 
The hydroxyl and other products of the glow discharge generator 20" are 
delivered via outlet 70 to the combustion gas stream. 
FIG. 7 illustrates a different embodiment of a hydroxyl generator 20'". 
Hydroxyl generator 20'" contains an ozone generator 90 for ozone 
generation and an ultraviolet container 95 for ozone dissociation and 
hydroxyl creation. The ozone generator 90 has an electrolytic cell 91 
which receives water via water inlet 92. Water for the electrolytic cell 
91 can be supplied from an external source which is stored or it may be 
condensed and collected from the water vapor in the exhaust gas stream and 
produced from combustion. The electrolytic cell is connected to an 
overvoltage power supply 93. An overvoltage electrolytic cell operates at 
a few tenths of a volt above the voltage condition required for the 
voltage threshold required for electrolysis. The electrolytic cell 91 
generates ozone, oxygen and water vapor which is retained by container 94. 
Container 94 has an ozone, oxygen and water vapor outlet 96 which provides 
a passage to the ultraviolet container 95. 
Ultraviolet container 95 has an ultraviolet lamp 21' which produces 253.7 
nm radiation in order to dissociate the ozone into hydroxyl pursuant to 
the sequence of reactions described earlier in connection with FIG. 5. The 
ultraviolet lamp 21' is connected to a power supply 60. Unlike the 
ultraviolet lamp 21 in FIG. 5, lamp 21' only needs to generate UV 
radiation having a wavelength of above 200 nm and preferably approximately 
254 nm. The inside surface of ultraviolet container 95 is provided with a 
surface which is highly reflective of UV radiation having a wavelength 
above 200 nm and preferably approximately 254 nm. 
In a further alternative, lamp 21 can be mounted downstream from the 
engine's combustion chamber, for example, in the exhaust manifold 15 as 
best seen in FIG. 3. By irradiating the exhaust stream with UV radiation 
in the 100 to 200 nm wavelength range, in the presence of sufficient water 
vapor, hydroxyl will be produced by direct photodissociation. 
In addition, hydroxyl generators 20, 20', 20" and 20'" can inject hydroxyl 
both upstream and downstream of the combustion chamber. 
It should be noted that the embodiments discussed above are illustrative 
examples. In this regard, while the use of radiant energy to produce 
hydroxyl is described above, the present invention is not so limited and 
other devices well-known in the art which produce hydroxyl are envisioned 
as sources for adding hydroxyl to the combustion gas stream in accordance 
with the teachings of the present invention. 
In addition, it should be noted that the only requirement of the present 
invention is that the hydroxyl is added to the combustion gas stream at a 
point upstream of or at the catalytic converter, for example, the air 
intake duct to the carburetor or fuel-injection systems of the combustion 
chamber, the air/fuel intake manifold to the combustion chamber, the 
combustion chamber directly or the exhaust manifold of the combustion 
chamber, or the exhaust pipe 12 as shown in FIG. 1. 
Moreover, while the present invention has been described with reference to 
a catalytic converter, it is contemplated that only the high surface area 
provided by the converter in conjunction with the introduction of hydroxyl 
would be required to reduce the pollutants in the exhaust gases of a 
combustion engine. 
A control arrangement can be employed according to a further embodiment of 
the present invention as shown in FIG. 8, wherein an engine sensor 16 is 
installed in the system. The sensor 16 is connected to a controller 18 
which can be an electronic system which is controlled by the output of 
engine sensor 16 or as complex as an engine control computer which 
analyzes the output of the sensor 16 in conjunction with other engine 
parameters such as load, temperature, throttle position, rpm and the like, 
and which can modulate the output of the hydroxyl generator 20. 
Alternatively, the controller 18 can vary the amount of hydroxyl generated 
by the hydroxyl generator 20 by varying either the voltage or current 
applied to the hydroxyl generator 20 by the voltage converter 24 based on 
inputs received from the engine sensor 16. 
In an alternative embodiment a single hydroxyl generator may contain more 
than one ultraviolet lamp 21a, 21b, 21c which each convert air to hydroxyl 
at a level that is less than required for complete elimination of 
pollutants produced by combustion of a fuel. One lamp 21a is operated when 
determined necessary, such as when the engine is operating, and the other 
lamp 21b is modulated depending upon operating parameters as measured by 
the engine sensor 16. 
In this embodiment, a controller 18 is connected to an engine sensor 16 to 
receive an input indicative of the current engine operating parameters or 
conditions. When the controller 18 senses an engine condition or 
parameter, such as engine speed or engine load at or above a predetermined 
level, the controller 18 modulates lamp 21b and the output of the hydroxyl 
generator. In addition to a two generator or two lamp configuration, a 
plurality of generators or lamps can be used such that one generator or 
lamp is continuously operated when the engine is operating and each 
additional generator or lamp is turned on in succession as different and 
increasing levels of engine operating conditions or parameters, such as 
rotation of the engine or engine load, are sensed by the controller 18 so 
that all the generators or lamps are operating when the engine parameter 
or condition, such as speed or engine load, is at the highest 
predetermined level and sufficient hydroxyl is generated to assure no 
excess pollutants are generated. 
In a similar arrangement, instead of a plurality of lamps 21, a plurality 
of sets of inner electrodes 83 and outer electrodes 81, or a plurality of 
ozone generators 90 and ultraviolet light containers 95, or a plurality of 
lamps 21' can be utilized. 
Alternatively, a single lamp 21 can be employed and the controller 18 can 
vary the amount of hydroxyl generated by the lamp 21 by varying either the 
voltage or current applied to the lamp 21 by the voltage converter 24 
based on inputs received from the controller 18. 
Referring to FIG. 9, the method of the present invention is illustrated and 
comprises the steps of: 1) adding hydroxyl to the combustion gas stream at 
a point upstream from a high surface area receptacle, and 2) passing the 
exhaust gases through a high surface area receptacle such as, for example, 
a typical automotive catalytic converter. 
Although the present invention has been described with particular reference 
to its preferred embodiments, it should be understood that many variations 
and modifications will now be obvious to those skilled in that art and, 
therefore, the scope of the invention should not be limited, by the 
specific disclosure herein, but only by the appended claims.