Gm Global Technolgoy Operations, Inc.

Pohang University of Science and Technology Foundation

Byong Kwon Cho

Steven Jeffrey Schmieg

Se Hyuck Oh

Jong-Hwan Lee

Richard J Blint

Joon Hyun Baik

Ayyappan Subbiah

Thomas J Chapaton

In-Sik Nam

Jong H Lee

Kenneth B Gross

Daniel Dziedzic

Jerome P Ortmann

Christopher J Stock

Joon-Hyun Baik

Keith L Olson

Sung Dae Yim

Joo-Hyun Baik

A method for reducing nitrogen oxides including NO and NOin an exhaust stream also including oxygen, carbon monoxide and hydrocarbons at a temperature above about 150&#xb0; C. includes oxidizing NO in the exhaust stream to NO, adding diesel fuel hydrocarbons and their oxygenates to the exhaust stream for the reduction of nitrogen oxides, and flowing the exhaust stream through a dual bed catalyst system including a first bed and a second bed, wherein the first bed is a single layer catalyst bed and the second bed is a double layer catalyst bed including a first layer and a second layer to reduce the nitrogen oxides to N.

Dual bed catalyst system for NOx reduction in lean-burn engine exhaust

A catalyst made by the introduction of copper ions and cobalt ions into a Y-type zeolite to produce a CuCoY zeolite improves the reduction of NOx in exhaust from a lean burn engine, such as a diesel engine. A dual bed selective reduction reactor in the exhaust stream comprising a first bed of BaY or of Ag/alumina and a second bed of CuCoY is particularly effective in reduction of NOx. In one embodiment, the exhaust stream is suitably treated with an oxidant, such as ozone, and a reductant, such as a diesel hydrocarbon or oxygenated diesel hydrocarbon, before the exhaust passes in contact with the dual bed catalyst.

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A method for reducing nitrogen oxides including NO and NO2 in an exhaust stream also comprising oxygen, carbon monoxide and hydrocarbons at a temperature above about 150&#xb0; C., the method including in embodiments oxidizing NO in the exhaust stream to NO2; reforming raw diesel fuel to produce OHC's from the fuel; adding diesel fuel hydrocarbons and their oxygenates to the exhaust stream for the reduction of nitrogen oxides; and contacting the exhaust stream with a reduction hybrid catalyst comprising BaY&#x2014;Ag/Al2O3 to reduce the nitrogen oxides to N2. The method reduces NOx initially through the (HC+OHC)/SCR process producing N2, while also producing NH3 as a byproduct over Ag/Al2O3. The NH3 subsequently reduces NOx over the BaY&#x2014;Ag/Al2O3 hybrid catalyst through the NH3/SCR process, producing more N2 and thereby enhancing the NOx reduction efficiency of the hybrid catalyst system.

Hybrid catalyst for NOx reduction using fuel hydrocarbons as reductant

A method of reducing NOin a lean burn engine exhaust stream from a hydrocarbon burning engine may be first passing the exhaust stream over a thrifted diesel oxidation catalyst that substantially completes the oxidation of carbon monoxide to carbon dioxide and the oxidation of hydrocarbons (HC) to carbon dioxide and water. Next, separate additions of ozone and ammonia or urea may be introduced to the exhaust gas stream upstream of the catalytic reduction reactor at temperatures below 250 degrees Celsius. The additions of ozone and ammonia or urea modify the exhaust gas composition to improve the performance of NOreduction catalysts in the catalytic reduction reactor. At temperatures above 250 degrees, the ozone addition may be reduced or eliminated, while the ammonia addition can be controlled as a function of the amount of NOx in the exhaust stream and the temperature of the catalytic reduction reactor.

Raw diesel fuel is reformed to produce partially oxygenated hydrocarbons in the liquid fuel by use of a nonthermal plasma reactor. The reformed diesel fuel is formed by passing a stream of air plasma bubbles through a liquid volume of diesel fuel to strip low molecular weight hydrocarbons from the fuel, while partially oxygenating an abundance of them as a reformate for addition to the exhaust. This reformed diesel fuel is introduced as a sidestream into the exhaust of a diesel engine or other lean-burn power plants as reactants for selective catalytic reduction of nitrogen oxides in the exhaust. Fresh fuel is added to the liquid volume as diesel reformate is stripped from it, and a portion of the stripped fuel is withdrawn from the liquid volume.

Continuous reforming of diesel fuel for NOx reduction

Ozone, preferably produced in an ambient air stream passed through a non-thermal hyperplasma reactor, is added to the hot exhaust gas stream from a lean-burn (oxygen-rich) combustion source. The ozone converts much of the NO in the NOcontaining exhaust stream to NO. The resulting NO/NOratio can be controlled by the input energy density to the plasma reactor. Ammonia and/or urea is added to the ozone treated exhaust in proportion to the NOcontent, and the stream passed into contact with a reduction catalyst, such as a base metal-exchanged zeolite, to convert the NOto nitrogen.

The nitric oxide (NO) and nitrogen dioxide (NO) content of lean-burn engine exhaust is beneficially prepared for selective catalytic reduction (SCR) of these oxides to nitrogen by two sidestream additions to the exhaust. An ozone-containing air stream is added to the exhaust to affect oxidation of NO to NO. And a hydrocarbon(s) fuel constituent is added to a second humidified ozone-containing air stream and that mixture subjected to UV radiation. Strongly oxidizing hydroxyl radicals are formed by interaction of ozone, water, and UV radiation for reaction with the hydrocarbon. The resulting partially oxidized hydrocarbons (Pox) are added to the exhaust, providing effective reduction materials for the SCR of NOto nitrogen and water.

The selective catalytic reduction of nitrogen oxides (especially NO and NO) in exhaust from diesel and other lean burn engines is improved by use of a compact hyperplasma reactor for generating ozone and other highly oxidizing species in a stream of air. A portion of the ozone containing air stream is blown directly into the exhaust for oxidizing NO to NO. The other portion of plasma treated air is used to fractionate and reform a volume of diesel fuel to produce low molecular weight hydrocarbons and oxidized hydrocarbons to be added to the exhaust as NOreductants in the catalytic reduction.

Reforming diesel fuel for NOx reduction

This invention provides a method of reducing nitrogen oxides in an oxygen containing exhaust stream using ethanol as a reductant for plasma-assisted selective catalytic reduction. The exhaust gas, generated from a diesel engine or other lean-burn power source, comprises nitrogen oxides, especially NO. Ozone generated from a plasma reactor is injected into the exhaust stream to convert NO to NOand the plasma injection is followed by the addition of ethanol. The NOis then reduced by contacting the exhaust stream with a dual-bed catalytic reactor comprising BaY (or NaY) and CuY zeolite catalysts in the presence of ethanol as the reductant. The plasma power density and the molar ratio of ethanol to NOx fed to the catalytic reactor are controlled as a function of the catalyst temperature for the best performance of the plasma-catalyst system. An average conversion of NOto Nof at least 90% is achieved over the temperature range of 200&#x2013;400&#xb0; C.

Method of reducing NOx in diesel engine exhaust

A plasma reactor for automotive exhaust gas applications which efficiently promotes diffusion, mass transfer and chemical reaction processes of atoms, ions and radicals, in that the ground (outer) electrode has an axially discrete pattern which provides alternating regions of active and passive electric field along the axial direction of the plasma reactor. As the exhaust gas passes axially along the plasma reactor, each active region produces plasma atoms, ions and radicals, which then have time to react with the NOover the course of the adjacent passive region. In this manner, successive active regions produce copious atoms, radicals and ions, and the adjacent passive regions provide time for these radicals and ions to react with the NOand hydrocarbons before the next active region is encountered by the moving stream of exhaust gas, thereby enhancing the performance of the plasma reactor.

Plasma reactor having regions of active and passive electric field

A zeolite catalyst and a process for preparing a zeolite catalyst which is both capable of catalyzing the removal of nitrogen oxides from a gaseous medium across a broad temperature range and is operationally and hydrothermally stable at high reaction temperatures. The zeolite catalyst includes a zeolite carrier having a mole ratio of typically from about 14 to about 95 and copper ions supported on the zeolite carrier. The zeolite catalyst is prepared by providing a zeolite carrier, reacting copper with the zeolite carrier by carrying out an ion exchange reaction in a cupric salt aqueous solution at a temperature of between about 4&#xb0; C. and room temperature (25&#xb0; C.), and then drying and calcining the catalyst.

A sidestream located hyper-plasma reactor having an axially discrete pattern of alternating regions of active and passive electric field along the axial direction. The hyper-plasma reactor has great efficacy in terms of ultra low power consumption and copious production of NOconverting aldehydes in the absence of NO by applying plasma power only to an air and hydrocarbon mix sidestream gas flow. Only a small fraction (1% to 2%) of plasma power is required as compared to that for a conventional plasma reactor to treat the full exhaust gas stream. The hyper-plasma reactor produces ozone which reacts subsequently with hydrocarbons to produce aldehydes ('ozonolysis'). The sidestream location of the hyper-plasma reactor allows for the full exhaust stream to bypass it, without significantly affecting the overall NOconversion performance in the catalytic converter.

Ultra low power plasma reactor system for automotive NOx emission control

The reduction of NOin diesel engine exhaust gas, typically at about 200&#xb0; C. to 400&#xb0; C., is accomplished using a dual bed NaY&#x2014;CuY zeolite reduction catalyst. The effectiveness of the catalyst in reducing the nitrogen oxides is markedly increased by the separate and sequential additions of plasma reformed diesel fuel and ozone to the exhaust before it contacts the powdered catalyst. Reformed diesel fuel is obtained by withdrawing fuel from on-board storage, heating the withdrawn volume and stripping a more volatile fraction with air and passing the air/volatile diesel fuel fraction through a non-thermal plasma reactor. Ozone is obtained by blowing ambient air through a second non-thermal plasma reactor.

No reduction with diesel fuel reformed by nonthermal hyperplasma

Certain metal-exchanged SUZ-4 zeolites have been prepared that have catalytic activity for the reduction of NOx in the exhaust of a hydrocarbon or alcohol fueled engine operated under fuel lean conditions. Initially the SUZ-4 zeolite contains alkali metal cations such as Li, Na, Kand/or Cs. These alkali metal cation-containing zeolites are partially exchanged with at least one of copper (II), silver (I), iron (III) or cobalt (II) ions. The resulting partially exchanged SUZ-4 zeolites display such activity and are stable under extreme hydrothermal aging conditions.

Hydrothermally stable catalyst for improved lean NOx reduction

Certain metal-exchanged SUZ-4 zeolites have been prepared that have catalytic activity for the reduction of NOx in the exhaust of a hydrocarbon or alcohol fueled engine operated under fuel lean conditions. Initially the SUZ-4 zeolite contains alkali metal cations such as Li , Na , K and/or Cs . These alkali metal cation-containing zeolites are partially exchanged with at least one of copper (II), silver (I), iron (III) or cobalt (II) ions. The resulting partially exchanged SUZ-4 zeolites display such activity and are stable under extreme hydrothermal aging conditions.

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Rochester Hills, MI, United States of America

Byong Kwon Cho