CA1076959A - Exhaust system - Google Patents
Exhaust systemInfo
- Publication number
- CA1076959A CA1076959A CA290,096A CA290096A CA1076959A CA 1076959 A CA1076959 A CA 1076959A CA 290096 A CA290096 A CA 290096A CA 1076959 A CA1076959 A CA 1076959A
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- Canada
- Prior art keywords
- catalyst
- exhaust
- inlet
- baffles
- exhaust gas
- Prior art date
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Abstract
EXHAUST SYSTEMS
ABSTRACT OF THE DISCLOSURE
The useful life of a catalyst being used in an engine exhaust system to lower the undesirable constituents in the exhaust gas of an engine being operated on gasoline containing a cyclopentadienyl manganese antiknock is greatly prolonged by providing an exhaust system having a plurality of baffles in the exhaust flow path upstream from the catalyst forming a tortuous flow path.
ABSTRACT OF THE DISCLOSURE
The useful life of a catalyst being used in an engine exhaust system to lower the undesirable constituents in the exhaust gas of an engine being operated on gasoline containing a cyclopentadienyl manganese antiknock is greatly prolonged by providing an exhaust system having a plurality of baffles in the exhaust flow path upstream from the catalyst forming a tortuous flow path.
Description
10~;'6959 BACKGROUND
... . . _ Cyclopentadienyl maganese compounds are excellent antiknocks in gasoline used to operate spark ignited internal combustion engines. Use of such compounds as antiknocks is described in U.S. 2,818,417 (Brown et al) issued December 31, 1957; U.S. 2,839,552 (Shapiro et al) issued June 17, 1958 and U.S. 3,127,351 (Brown et al~issued March 31, 1964. Not only are these compounds effective antiknock agents, but it has also been found that they do not adversely affect the activity of ;~ 10 catalysts used to decrease the amount of undesirable constituents in engine exhaust gas. Under some operating conditions it has been found that, although the manganese antiknocks do not lessen the activity of the exhaust gas catalyst, they can inter-act in some manner at the surface of the catalyst bed leading to a reduction in the size of the openings into the bed thereby causing an increase in exhaust back pressure. The present invention provides a simple effective means of alleviating this problem.
SUMMARY
.
,~ 20 Broadly speaking, the present invention provides a method of preventing the early plugging of an exhaust gas ~, catalyst being used in an exhaust system of an internal combustion engine at a location where the temperature of the exhaust gas initially contacting the catalyst exceeds about ` 1000F. during normal engine cruise conditions, the catalyst being used to lower the amount of undesirable constituents in the exhaust gas from an internal combustion engine operating on a liquid hydrocarbon fuel containing a cyclopentadienyl manganese antiknock compound, the method comprising passing the exhaust gas through a conduit section containing a sexies of .
baffles, each of the baffles having at least one large opening through which exhaust gas can pass, the openings being arranged .,: -- 1 --., ~, ~ .
.. . . . .
. . ~ . . ~
~ 7~i9S9 such that the openings in one baffle are not substantially in.axial alignment with the openings in an adjacent baffle, the space between each baffle being empty, the baffles forming an unimpeded tortuous flow path, and then passing the exhaust gas into a catalytic reactor containing the catalyst whereby the exhaust gas passes through the catalyst, the baffles functioning to inhibit the plugging of the catalyst by manganese compounds in the exhaust gas.
The above method may be carried out in an exhaust system for an internal combustion engine, the exhaust system including a catalytic reactor at a location where inlet exhaust temperature exceeds about 1000F. during normal engine cruise conditions, the catalytic reactor being defined by a reactor ' housing having an inlet and an outlet and having a catalyst . bed disposed between the inlet and the outlet, the space ;: between the inlet and the entry face of the catalyst form.ing an expansion zone wherein the exhaust flow cross-section e.xpands .. ... .
from the cross-sectional area of the inlet to the surface area of the entry face, the inlet being operatively connected by exhaust conduit means to the exhaust outlet of the engine, the catalyst comprising a catalytic metal supported on a honey-. comb monolithic ceramic support which is prone to plugging when '~ the engine is operated on gasoline containing a cyclopentadienyl manganese antiknock, the improvement comprising a plurality of transverse baffles located in the exhaust conduit means upstream ~.
from and proximate to the inlet, each of the baffles having at least one large opening through.which exhaust gas can pass, the openings being arxanged such that the openings in one baffle are not substantially in axial alignment with the openings 30 in an adjacent baffle, the space between the baffles being empty,the baffles forming an unimpeded tortuous flow path and function-: ing to inhibit the plugging of the catalyst by manganese
... . . _ Cyclopentadienyl maganese compounds are excellent antiknocks in gasoline used to operate spark ignited internal combustion engines. Use of such compounds as antiknocks is described in U.S. 2,818,417 (Brown et al) issued December 31, 1957; U.S. 2,839,552 (Shapiro et al) issued June 17, 1958 and U.S. 3,127,351 (Brown et al~issued March 31, 1964. Not only are these compounds effective antiknock agents, but it has also been found that they do not adversely affect the activity of ;~ 10 catalysts used to decrease the amount of undesirable constituents in engine exhaust gas. Under some operating conditions it has been found that, although the manganese antiknocks do not lessen the activity of the exhaust gas catalyst, they can inter-act in some manner at the surface of the catalyst bed leading to a reduction in the size of the openings into the bed thereby causing an increase in exhaust back pressure. The present invention provides a simple effective means of alleviating this problem.
SUMMARY
.
,~ 20 Broadly speaking, the present invention provides a method of preventing the early plugging of an exhaust gas ~, catalyst being used in an exhaust system of an internal combustion engine at a location where the temperature of the exhaust gas initially contacting the catalyst exceeds about ` 1000F. during normal engine cruise conditions, the catalyst being used to lower the amount of undesirable constituents in the exhaust gas from an internal combustion engine operating on a liquid hydrocarbon fuel containing a cyclopentadienyl manganese antiknock compound, the method comprising passing the exhaust gas through a conduit section containing a sexies of .
baffles, each of the baffles having at least one large opening through which exhaust gas can pass, the openings being arranged .,: -- 1 --., ~, ~ .
.. . . . .
. . ~ . . ~
~ 7~i9S9 such that the openings in one baffle are not substantially in.axial alignment with the openings in an adjacent baffle, the space between each baffle being empty, the baffles forming an unimpeded tortuous flow path, and then passing the exhaust gas into a catalytic reactor containing the catalyst whereby the exhaust gas passes through the catalyst, the baffles functioning to inhibit the plugging of the catalyst by manganese compounds in the exhaust gas.
The above method may be carried out in an exhaust system for an internal combustion engine, the exhaust system including a catalytic reactor at a location where inlet exhaust temperature exceeds about 1000F. during normal engine cruise conditions, the catalytic reactor being defined by a reactor ' housing having an inlet and an outlet and having a catalyst . bed disposed between the inlet and the outlet, the space ;: between the inlet and the entry face of the catalyst form.ing an expansion zone wherein the exhaust flow cross-section e.xpands .. ... .
from the cross-sectional area of the inlet to the surface area of the entry face, the inlet being operatively connected by exhaust conduit means to the exhaust outlet of the engine, the catalyst comprising a catalytic metal supported on a honey-. comb monolithic ceramic support which is prone to plugging when '~ the engine is operated on gasoline containing a cyclopentadienyl manganese antiknock, the improvement comprising a plurality of transverse baffles located in the exhaust conduit means upstream ~.
from and proximate to the inlet, each of the baffles having at least one large opening through.which exhaust gas can pass, the openings being arxanged such that the openings in one baffle are not substantially in axial alignment with the openings 30 in an adjacent baffle, the space between the baffles being empty,the baffles forming an unimpeded tortuous flow path and function-: ing to inhibit the plugging of the catalyst by manganese
- 2 -, ~ -'` 107~959 :
compounds in the exhaust gas.
Furthermore, the present invention provides a catalytic reactor resistant to plu~ging when used in the exhaust system of an internal combustion engine operating on gasoline containing a cyclopentadienyl manganese antiknock ; compound, the catalytic reactor comprising a reactor housing having an inlet and an outlet and containing a catalyst bed between the inlet and the outlet such that the exhaust gas passes through the catalyst bed in passing from the inlet to the outlet, the inlet having a cross-sectional area substantially less than the area of the entry face of the catalyst, the housing having an expansion zone between the inlet and the entry face, the reactor including a conduit section connected to the inlet extending away from the expansion zone, the conduit section containing a plurality of transverse baffles, each of the baffles having at least one large opening "
~ through which exhaust gas can pass, the openings being arranged .. . .
such that the openings in one baffle are not substantially in axial alignment with the openings in an adjacent baffle, the space between each baffle being empty, the baffles forming an ; unimpeded tortuous flow path through the conduit section, the ~; baffles functioning to inhibit the plugging of the catalyst bed by manganese compounds in the exhaust gas.
: DESCRIPTION OF l~HE DRAWINGS
Figure 1 is a longitudinal cross-section of a catalytic exhaust reactor having a baffle unit connected to its inlet.
Figure 2 is a plan view of each of the baffle disks taken from the baffle unit of Figure 1.
Figure 3 is a plan vie~ of an optional set of baffle disks suitable for use in the baffle unit of Figure 1.
Figure 4 is a plan view of another optional set of ."' ~ ' :
` - 2a -`~ ~
, . , ~-- 107t;~59 baffle disks suitable for use in the baffle unit of Figure 1.
: Figure 5 is a longitudinal cross-section of a catalytic exhaust reactor having baffle disks located in its inlet plenum.
Figure 6 is a plan view of the baffle disks taken from the inlet plenum of Figure 5.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
j: A preferred embodiment of the invention is an exhaust 1 system for a spark ignited internal combustion engine comprising ; 10 a ca-talytic exhaust reactor connected to the exhaust outlet of ; the engine and including a plurality of baffles in the exhaust ~, flow path between the catalyst bed and the engine. The baffles are arranged transverse to the direction of exhaust flow and ~' form a tortuous flow path.
The essential elements of such a system are shown ;. in Figure 1. Catalytic reactor 1 is formed by enlarged ~,' cylindrical-frustoconical housing 2 having inlet 3 and outlet , 4. Located within housing 2 is catalyst bed 5 which, in this embodiment, is ~ ;. .
i' .
.
,, .
.
., ~ .
~ ~ .
....
.
. - 2b -: .
~ ~07~959 a honeycomb alumina-magnesia-silica monolithic ceramic supported platinum catalyst as described in U.S. Patent 3,441,381.
Connected to inlet 3 is baffle unit 6 comprising tubular housing 7 containing baffle disks 9, 10, 11 and 12.
These disks can be welded to the inside of housing 7 or held in place by any equivalent means. They are preferably but not necessarily spaced about 1/4" - 2" apart, and more preferably about 1/4" - 1/2" apart. Each baffle disk can be seen to have openings of various shapes which when installed in housing 7 are not in substantial alignment with the openings in an adjacent disk and thus form a tortuous flow path through -housing 7. In other words, when the exhaust gas passes through an opening in the first element it encounters a sur-face on the second element, causing it to abruptly change lS directions and flow to openings in the second element. After passing through openings in the second element, it again en-counters a surface of the third element, again causing it to change directions to seek the openings in the third ~ element, etc. As shown, disks 9, 10, 11 and 12 also contain - 20 small perforations in their "non-opening" surface, which has ~. . .
been found to give good results.
Disk baffles 9A, lOA, llA and 12A of Figure 3, or - 9B, lOB, llB and 12B of Figure 4, can optionally be substituted for disks 9, 10, 11 and 12.
Baffle unit 6 is connected by pipe 15 to the ex-haust outlet of an internal combustion engine (not shown) and is adapted to conduct hot exhaust gas from the engine to baffle unit 6 from which it proceeds directly into catalytic reactor 1.
In order to obtain rapid warm-up required for catalyst activation, the catalytic reactor is preferably located proximate , ' :
:~
-' 10'76959 to the engine exhaust outlet. In some embodiments catalytic ; reactor 1 is connected through baffle unit 6 directly to the !~; engine exhaust manifold outlet. In fact, baffle unit 6 can be constructed as part of the internal structure of the exhaust ~ manifold thereby permitting direct connection of catalytic : reactor 1 to the manifold outlet.
; ` As mentioned above, the catalytic reactor is ,!, ~ preferably, but not necessarily, proximate to the engine.
~: .
~- By "proximate" is meant that it is close enough such that - 10 the catalyst bed is rapidly heated to "light-off" or activation temperature. The exhaust gas temperature required ~ to accomplish this is dependent upon the nature of the ; catalyst. Noble metal catalysts or those containing at leasi some noble metal light-off at much lower exhaust temperatures, e.g., 350-500F. However, in order to insure early light-off, the catalytic reactor is preferably located such that the .;~ , , S, inlet exhaust temperature is above about 1000F., and more ;~ preferably above about 1400F., during normal engine cruise `,;.
~, conditions. It is also under these conditions that the ; ., ` 20 cyclopentadienyl manganese antiknocks are most likely to plug the catalyst and, hence, it is under these preferred conditions that the present invention is most useful.
- The exhaust system of this invention is useful in both chemical oxidation and reduction applications of :- catalytic exhaust reactors. When reduction of nitrogen oxides is desired the engine is operated slightly rich ~e,g., below 14/1 air/fuel ratio) without employing air injection. When oxidation of hydrocarbons and carbon monoxide is desired the oxygen content of the exhaust gas is increased by either - 30 operating lean (e.g., above 15/1 air/fuel ratio) or by , . .. .
injecting air into the exhaust gas, or both. The present : ':
` invention is most useful when used in exhaust gas oxidation.,`. , .
bm ~
.
-- 10~7ti9S9 applications,although it is by no means limited to this, As stated above, the embodiment being discussed uses a honeycomb monolithic ceramic supported platinum catalyst as described in U.S. 3,441,381. These are made by coating a corrugated ceramic structure such as described in U.S.
compounds in the exhaust gas.
Furthermore, the present invention provides a catalytic reactor resistant to plu~ging when used in the exhaust system of an internal combustion engine operating on gasoline containing a cyclopentadienyl manganese antiknock ; compound, the catalytic reactor comprising a reactor housing having an inlet and an outlet and containing a catalyst bed between the inlet and the outlet such that the exhaust gas passes through the catalyst bed in passing from the inlet to the outlet, the inlet having a cross-sectional area substantially less than the area of the entry face of the catalyst, the housing having an expansion zone between the inlet and the entry face, the reactor including a conduit section connected to the inlet extending away from the expansion zone, the conduit section containing a plurality of transverse baffles, each of the baffles having at least one large opening "
~ through which exhaust gas can pass, the openings being arranged .. . .
such that the openings in one baffle are not substantially in axial alignment with the openings in an adjacent baffle, the space between each baffle being empty, the baffles forming an ; unimpeded tortuous flow path through the conduit section, the ~; baffles functioning to inhibit the plugging of the catalyst bed by manganese compounds in the exhaust gas.
: DESCRIPTION OF l~HE DRAWINGS
Figure 1 is a longitudinal cross-section of a catalytic exhaust reactor having a baffle unit connected to its inlet.
Figure 2 is a plan view of each of the baffle disks taken from the baffle unit of Figure 1.
Figure 3 is a plan vie~ of an optional set of baffle disks suitable for use in the baffle unit of Figure 1.
Figure 4 is a plan view of another optional set of ."' ~ ' :
` - 2a -`~ ~
, . , ~-- 107t;~59 baffle disks suitable for use in the baffle unit of Figure 1.
: Figure 5 is a longitudinal cross-section of a catalytic exhaust reactor having baffle disks located in its inlet plenum.
Figure 6 is a plan view of the baffle disks taken from the inlet plenum of Figure 5.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
j: A preferred embodiment of the invention is an exhaust 1 system for a spark ignited internal combustion engine comprising ; 10 a ca-talytic exhaust reactor connected to the exhaust outlet of ; the engine and including a plurality of baffles in the exhaust ~, flow path between the catalyst bed and the engine. The baffles are arranged transverse to the direction of exhaust flow and ~' form a tortuous flow path.
The essential elements of such a system are shown ;. in Figure 1. Catalytic reactor 1 is formed by enlarged ~,' cylindrical-frustoconical housing 2 having inlet 3 and outlet , 4. Located within housing 2 is catalyst bed 5 which, in this embodiment, is ~ ;. .
i' .
.
,, .
.
., ~ .
~ ~ .
....
.
. - 2b -: .
~ ~07~959 a honeycomb alumina-magnesia-silica monolithic ceramic supported platinum catalyst as described in U.S. Patent 3,441,381.
Connected to inlet 3 is baffle unit 6 comprising tubular housing 7 containing baffle disks 9, 10, 11 and 12.
These disks can be welded to the inside of housing 7 or held in place by any equivalent means. They are preferably but not necessarily spaced about 1/4" - 2" apart, and more preferably about 1/4" - 1/2" apart. Each baffle disk can be seen to have openings of various shapes which when installed in housing 7 are not in substantial alignment with the openings in an adjacent disk and thus form a tortuous flow path through -housing 7. In other words, when the exhaust gas passes through an opening in the first element it encounters a sur-face on the second element, causing it to abruptly change lS directions and flow to openings in the second element. After passing through openings in the second element, it again en-counters a surface of the third element, again causing it to change directions to seek the openings in the third ~ element, etc. As shown, disks 9, 10, 11 and 12 also contain - 20 small perforations in their "non-opening" surface, which has ~. . .
been found to give good results.
Disk baffles 9A, lOA, llA and 12A of Figure 3, or - 9B, lOB, llB and 12B of Figure 4, can optionally be substituted for disks 9, 10, 11 and 12.
Baffle unit 6 is connected by pipe 15 to the ex-haust outlet of an internal combustion engine (not shown) and is adapted to conduct hot exhaust gas from the engine to baffle unit 6 from which it proceeds directly into catalytic reactor 1.
In order to obtain rapid warm-up required for catalyst activation, the catalytic reactor is preferably located proximate , ' :
:~
-' 10'76959 to the engine exhaust outlet. In some embodiments catalytic ; reactor 1 is connected through baffle unit 6 directly to the !~; engine exhaust manifold outlet. In fact, baffle unit 6 can be constructed as part of the internal structure of the exhaust ~ manifold thereby permitting direct connection of catalytic : reactor 1 to the manifold outlet.
; ` As mentioned above, the catalytic reactor is ,!, ~ preferably, but not necessarily, proximate to the engine.
~: .
~- By "proximate" is meant that it is close enough such that - 10 the catalyst bed is rapidly heated to "light-off" or activation temperature. The exhaust gas temperature required ~ to accomplish this is dependent upon the nature of the ; catalyst. Noble metal catalysts or those containing at leasi some noble metal light-off at much lower exhaust temperatures, e.g., 350-500F. However, in order to insure early light-off, the catalytic reactor is preferably located such that the .;~ , , S, inlet exhaust temperature is above about 1000F., and more ;~ preferably above about 1400F., during normal engine cruise `,;.
~, conditions. It is also under these conditions that the ; ., ` 20 cyclopentadienyl manganese antiknocks are most likely to plug the catalyst and, hence, it is under these preferred conditions that the present invention is most useful.
- The exhaust system of this invention is useful in both chemical oxidation and reduction applications of :- catalytic exhaust reactors. When reduction of nitrogen oxides is desired the engine is operated slightly rich ~e,g., below 14/1 air/fuel ratio) without employing air injection. When oxidation of hydrocarbons and carbon monoxide is desired the oxygen content of the exhaust gas is increased by either - 30 operating lean (e.g., above 15/1 air/fuel ratio) or by , . .. .
injecting air into the exhaust gas, or both. The present : ':
` invention is most useful when used in exhaust gas oxidation.,`. , .
bm ~
.
-- 10~7ti9S9 applications,although it is by no means limited to this, As stated above, the embodiment being discussed uses a honeycomb monolithic ceramic supported platinum catalyst as described in U.S. 3,441,381. These are made by coating a corrugated ceramic structure such as described in U.S.
3,444,925 with a~ activated alumina (e g., gamma-alumina) and ;
a platlnum compound. The preferred ceramics are made accord-ing to U.S. 3,444,925 using alumina-silica (e.g., mullite, 3Al203 2SiO2), magnesia-alumina-silica (e.g., cordierite, 2MgO 2A12O3-5SiO2), or mixtures thereof. Palladium can be used in place of platinum, and since these elements generally occur in nature together, it is sometimes preferred to use mixtures of platinum and palladium.
The invention is not limited to honeycomb monolithic ceramic supported platinum or palladium catalysts, Examples of other catalytic metals include V, Cr, Mn, Fe, Co, Ni, Cu, zn, Zr, Nb, I~, Ru~ Rh, Ag~ W~ Re, Os~ Ir~ Pb, Ba( and the like~
These are generally used in an oxide form. They may be used individually or in various combinations such as Cu-Cr, Cu-Cr-V, Cu-Pd, Mn-Pd, Ni-Cr, and the like. They may be supported on the above monolithic ceramic support or on any other of numerous well-known catalyst supports such as granular, pelletized or extruded alumina, silica, silica-alumina, ` zirconia, magnesia, alumina-magnesia, and the like. Such catalysts are disclosed in U,S. 3,540,838; 3,524,721;
3,447,893; 3,433,581; 3,428,573; 3,425,792; 3,374,183;
3,271,324; 3,224,981; 3,224,831 and 3,207,704.
In operation, exhaust gas from the engine is conducted by pipe 15 to baffle unit 6 On passing through housing 7 the exhaust gas encounters baffle disks 9, 10, ll and 12. Openings in these disks are arranged such that .~
bm ~
.
.: , --` 10~7~9S9 -the exhaust gas after passing through the openings in one disk is forced to abruptly change direction prior to passing th:rough an opening in a subsequent disk -- in other words, the openings in the disks are arranged to form a tortuous path through the baffle unit.
Other disks such as 9A-12A or 9B-12B can be used in , ~ baffle unit 6 to form the tortuous path. The invention is not limited to the precise shape of the disks as long as they are arranged to form the required tortuous path.
: 10 . After passing through baffle unit 6, the exhaust ~ gas enters catalytic reactor 1 at inlet 3 and then enters .- catalyst bed 5. After traversing catalyst bed 5 wherein the amount of undesirable constituents are lowered, the exhaust : gas leaves catalyst reactor 1 at outlet 4 and is conducted ; by exhaust pipe 8 to a suitable exhaust location, In the embodiment of Figure 5 the baffle disks are , located within the catalytic reactor. Catalytic reactor 20 is formed by reactor housing 21 having inlet 22 and outlet 23, Located within housing 21 is catalyst bed 24 forming frusto-~ 20 conical inlet plenum 25 between catalyst bed 24 and inlet 22, . Baffle disks 26, 27, 28, 29 and 30 are positioned in plenum .,:
~:: 25 transverse to its longitudinal axis and are attached to the ~:- inside of housing 21 by any suitable means such as welding, Baffle disks 27-30 have a multitude of small perforations, Disks 26-30 have openings arranged such that the openings in : one disk are for the most part not axially in line with the : openings in the subsequent disk, Inlet 22 is connected by :~ pipe 31 to the exhaust outlet of the engine (not shown) and i :
~:. outlet 23 connects through pipe 32 to a suitable exhaust area~
: . ~
. ~ .
. .
. --6--i~ bm: ~
. .
` 1076959 -In operation, hot exhaust gas from the engine passes through pipe 31 to inlet 22 and enters inlet plenum 25 where it encounters baffle disks 26-30. The great majority of the exhaust gas passes through the large openings in the baffle disks and is thus forced to follow a tortuous path prior to reaching catalyst bed 24, The exhaust gas then passes through cataly~t bed 24 and leaves catalytic reactor 20 at outlet 23 from where it is conducted by pipe 32 to an exhaust area.
As stated previously, it is generally desirable to have the catalytic reactor close to the engine to insure early light-off. In one embodiment inlet 22 of catalytic reactor ' 20 is connected directly to the outlet of the engine exhaust manifold It is not clear exactly how the invention functions to reduce catalyst plugging by cyclopentadienyl manganese antiknocks, but tests have been conducted which show that it is highly effective in accomplishing this objective These tests were made using a single cylinder 36 CID engine operating on gasoline containing one gram of manganese per gallon as methylcyclopentadienyl manganese tricarbonyl, Air/fuel ratio was adjusted to approximately 16/1 to obtain 1.8 per cent oxygen in the exhaust. The engine was continuously operated at wide open throttle and the exhaust ..:
gas conducted to a catalytic reactor of the type shown in Figure 1 containing a honeycomb monolithic ceramic supported platinum catalyst (Engelhard Industries, Inc., PTX-313) The exhaust temperature at the catalyst inlet was about 1500F. in all tests. Exhaust back pressure was measured to ~` 30 determine degree of catalyst plugging. Initial back pressure , .
bm~
' - ' : . ' - ' was about 0.3 psig. An increase to 2 psig was considered a plugged catalyst bed. Results obtained compared to a no baffle control are shown in the following table.
Hours to Plu~ging control 45 3 baffles in inlet plenuml 174 3 baffles ahead of inlet2 360 l. Similar to Figure 5 2. As in Figure l As the results show, the present invention is highly effective in alleviating the catalyst plugging problem associated with use of exhaust gas catalysts in engines operating on fuel containing a manganese antiknock.
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.
.,~ . .
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., .
a platlnum compound. The preferred ceramics are made accord-ing to U.S. 3,444,925 using alumina-silica (e.g., mullite, 3Al203 2SiO2), magnesia-alumina-silica (e.g., cordierite, 2MgO 2A12O3-5SiO2), or mixtures thereof. Palladium can be used in place of platinum, and since these elements generally occur in nature together, it is sometimes preferred to use mixtures of platinum and palladium.
The invention is not limited to honeycomb monolithic ceramic supported platinum or palladium catalysts, Examples of other catalytic metals include V, Cr, Mn, Fe, Co, Ni, Cu, zn, Zr, Nb, I~, Ru~ Rh, Ag~ W~ Re, Os~ Ir~ Pb, Ba( and the like~
These are generally used in an oxide form. They may be used individually or in various combinations such as Cu-Cr, Cu-Cr-V, Cu-Pd, Mn-Pd, Ni-Cr, and the like. They may be supported on the above monolithic ceramic support or on any other of numerous well-known catalyst supports such as granular, pelletized or extruded alumina, silica, silica-alumina, ` zirconia, magnesia, alumina-magnesia, and the like. Such catalysts are disclosed in U,S. 3,540,838; 3,524,721;
3,447,893; 3,433,581; 3,428,573; 3,425,792; 3,374,183;
3,271,324; 3,224,981; 3,224,831 and 3,207,704.
In operation, exhaust gas from the engine is conducted by pipe 15 to baffle unit 6 On passing through housing 7 the exhaust gas encounters baffle disks 9, 10, ll and 12. Openings in these disks are arranged such that .~
bm ~
.
.: , --` 10~7~9S9 -the exhaust gas after passing through the openings in one disk is forced to abruptly change direction prior to passing th:rough an opening in a subsequent disk -- in other words, the openings in the disks are arranged to form a tortuous path through the baffle unit.
Other disks such as 9A-12A or 9B-12B can be used in , ~ baffle unit 6 to form the tortuous path. The invention is not limited to the precise shape of the disks as long as they are arranged to form the required tortuous path.
: 10 . After passing through baffle unit 6, the exhaust ~ gas enters catalytic reactor 1 at inlet 3 and then enters .- catalyst bed 5. After traversing catalyst bed 5 wherein the amount of undesirable constituents are lowered, the exhaust : gas leaves catalyst reactor 1 at outlet 4 and is conducted ; by exhaust pipe 8 to a suitable exhaust location, In the embodiment of Figure 5 the baffle disks are , located within the catalytic reactor. Catalytic reactor 20 is formed by reactor housing 21 having inlet 22 and outlet 23, Located within housing 21 is catalyst bed 24 forming frusto-~ 20 conical inlet plenum 25 between catalyst bed 24 and inlet 22, . Baffle disks 26, 27, 28, 29 and 30 are positioned in plenum .,:
~:: 25 transverse to its longitudinal axis and are attached to the ~:- inside of housing 21 by any suitable means such as welding, Baffle disks 27-30 have a multitude of small perforations, Disks 26-30 have openings arranged such that the openings in : one disk are for the most part not axially in line with the : openings in the subsequent disk, Inlet 22 is connected by :~ pipe 31 to the exhaust outlet of the engine (not shown) and i :
~:. outlet 23 connects through pipe 32 to a suitable exhaust area~
: . ~
. ~ .
. .
. --6--i~ bm: ~
. .
` 1076959 -In operation, hot exhaust gas from the engine passes through pipe 31 to inlet 22 and enters inlet plenum 25 where it encounters baffle disks 26-30. The great majority of the exhaust gas passes through the large openings in the baffle disks and is thus forced to follow a tortuous path prior to reaching catalyst bed 24, The exhaust gas then passes through cataly~t bed 24 and leaves catalytic reactor 20 at outlet 23 from where it is conducted by pipe 32 to an exhaust area.
As stated previously, it is generally desirable to have the catalytic reactor close to the engine to insure early light-off. In one embodiment inlet 22 of catalytic reactor ' 20 is connected directly to the outlet of the engine exhaust manifold It is not clear exactly how the invention functions to reduce catalyst plugging by cyclopentadienyl manganese antiknocks, but tests have been conducted which show that it is highly effective in accomplishing this objective These tests were made using a single cylinder 36 CID engine operating on gasoline containing one gram of manganese per gallon as methylcyclopentadienyl manganese tricarbonyl, Air/fuel ratio was adjusted to approximately 16/1 to obtain 1.8 per cent oxygen in the exhaust. The engine was continuously operated at wide open throttle and the exhaust ..:
gas conducted to a catalytic reactor of the type shown in Figure 1 containing a honeycomb monolithic ceramic supported platinum catalyst (Engelhard Industries, Inc., PTX-313) The exhaust temperature at the catalyst inlet was about 1500F. in all tests. Exhaust back pressure was measured to ~` 30 determine degree of catalyst plugging. Initial back pressure , .
bm~
' - ' : . ' - ' was about 0.3 psig. An increase to 2 psig was considered a plugged catalyst bed. Results obtained compared to a no baffle control are shown in the following table.
Hours to Plu~ging control 45 3 baffles in inlet plenuml 174 3 baffles ahead of inlet2 360 l. Similar to Figure 5 2. As in Figure l As the results show, the present invention is highly effective in alleviating the catalyst plugging problem associated with use of exhaust gas catalysts in engines operating on fuel containing a manganese antiknock.
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Claims (16)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In an exhaust system for an internal combustion engine, said exhaust system including a catalytic reactor at a location where inlet exhaust temperature exceeds about 1000° F. during normal engine cruise conditions, said catalytic reactor being defined by a reactor housing having an inlet and an outlet and having a catalyst bed disposed between said inlet and said outlet, the space between said inlet and the entry face of said catalyst forming an expansion zone wherein the exhaust flow cross-section expands from the cross-sectional area of said inlet to the surface area of said entry face, said inlet being operatively connected by exhaust conduit means to the exhaust outlet of said engine, said catalyst comprising a catalytic metal supported on a honeycomb monolithic ceramic support which is prone to plugging when said engine is operated on gasoline containing a cyclopentadienyl manganese antiknock, the improvement comprising a plurality of transverse baffles located in said exhaust conduit means upstream from and proximate to said inlet, each of said baffles having at least one large opening through which exhaust gas can pass, said openings being arranged such that the openings in one baffle are not substantially in axial alignment with the openings in an adjacent baffle, the space between said baffles being empty, said baffles forming an unimpeded tortuous flow path and functioning to inhibit the plugging of said catalyst by manganese compounds in said exhaust gas.
2. An exhaust system of Claim 1 wherein said exhaust after transversing said tortuous path passes directly into said catalyst bed.
3. An exhaust system of Claim 1 wherein said support is selected from the group consisting of alumina-silica, alumina-magnesia-silica, and mixtures thereof.
4. An exhaust system of Claim 3 wherein said support is selected from the group consisting of mullite, cordierite, and mixtures thereof.
5. An exhaust system of Claim 3 wherein said catalytic metal is selected from the group consisting of platinum, palladium, and mixtures thereof.
6. An exhaust system of Claim 1 wherein said baffles have a plurality of small perforations.
7. A catalytic reactor resistant to plugging when used in the exhaust system of an internal combustion engine operating on gasoline containing a cyclopentadienyl manganese antiknock compound, said catalytic reactor comprising a reactor housing having an inlet and an outlet and containing a catalyst bed between said inlet and said outlet such that said exhaust gas passes through said catalyst bed in passing from said inlet to said outlet, said inlet having a cross-sectional area substantially less than the area of the entry face of said catalyst, said housing having an expansion zone between said inlet and said entry face, said reactor including a conduit section connected to said inlet extending away from said expansion zone, said conduit section containing a plurality of transverse baffles, each of said baffles having at least one large opening through which exhaust gas can pass, said openings being arranged such that the openings in one baffle are not substantially in axial alignment with the openings in an adjacent baffle, the space between each baffle being empty, said baffles forming an unimpeded tortuous flow path through said conduit section, said baffles functioning to inhibit the plugging of said catalyst bed by manganese compounds in said exhaust gas.
8. A catalyst reactor of Claim 7 wherein said catalyst bed comprises a catalytic metal supported on a honeycomb monolithic ceramic support.
9. A catalytic reactor of Claim 8 wherein said support is selected from the group consisting of alumina-silica, alumina-magnesia-silica, and mixtures thereof.
10. A catalytic reactor of Claim 9 wherein said support is selected from the group consisting of mullite, cordierite, and mixtures thereof.
11. A catalytic reactor of Claim 9 wherein said catalyst metal is selected from the group consisting of platinum, palladium, and mixtures thereof.
12. A catalytic reactor of Claim 7 wherein said baffles have a plurality of small perforations.
13. A method of preventing the early plugging of an exhaust gas catalyst being used in an exhaust system of an internal combustion engine at a location where the temperature of the exhaust gas initially contacting said catalyst exceeds about 1000° F. during normal engine cruise conditions, said catalyst being used to lower the amount of undesirable constituents in the exhaust gas from an internal combustion engine operating on a liquid hydrocarbon fuel containing a cyclopentadienyl manganese antiknock compound, said method comprising passing said exhaust gas through a conduit section containing a series of baffles, each of said baffles having at least one large opening through which exhaust gas can pass, said openings being arranged such that the openings in one baffle are not substantially in axial alignment with the openings in an adjacent baffle, the space between each baffle being empty, said baffles forming an unimpeded tortuous flow path, and then passing said exhaust gas into a catalytic reactor containing said catalyst whereby said exhaust gas passes through said catalyst, said baffles functioning to inhibit the plugging of said catalyst by manganese compounds in said exhaust gas.
14. A method of Claim 13 wherein said catalyst comprises a catalytic metal supported on a honeycomb monolithic ceramic support.
15. A method of Claim 14 wherein said support is selected from the group consisting of alumina-silica, alumina-magnesia-silica, and mixtures thereof.
16. A method of Claim 15 wherein said catalytic metal is selected from the group consisting of platinum, palladium, and mixtures thereof.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA290,096A CA1076959A (en) | 1977-11-02 | 1977-11-02 | Exhaust system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA290,096A CA1076959A (en) | 1977-11-02 | 1977-11-02 | Exhaust system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1076959A true CA1076959A (en) | 1980-05-06 |
Family
ID=4109933
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA290,096A Expired CA1076959A (en) | 1977-11-02 | 1977-11-02 | Exhaust system |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1076959A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114382591A (en) * | 2022-01-24 | 2022-04-22 | 中国民用航空飞行学院 | Method for inhibiting deposition of antiknock product in cylinder of aviation piston engine |
-
1977
- 1977-11-02 CA CA290,096A patent/CA1076959A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114382591A (en) * | 2022-01-24 | 2022-04-22 | 中国民用航空飞行学院 | Method for inhibiting deposition of antiknock product in cylinder of aviation piston engine |
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