CA1045342A - Process for removing hydrocarbons - Google Patents

Abstract

PROCESS FOR REMOVING HYDROCARBONS

ABSTRACT OF THE DISCLOSURE:

Off-gas of internal combustion engines is freed from hydrocarbons. To this end, the hydrocarbons are reacted with oxygen-containing gas at temperatures within the range 200 and 800°C in contact with an inert carrier-supported catalyst having catalytically active copper, manganese and nickel oxides on the carrier, whereby the hydrocarbons are transformed to carbon monoxide and hydrogen.

Description

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. The presen-t invention relates to a process for removing h~drocarbons from -the o~f-gas of in~ternal combustion engines.
A process for removing hydrocarbons from the off-gas ~ of internal combustion engines has been described in I German published Specificati.on "Offe~Ale$ungsschriPt"
¦ 2 157 624, wherein the o~f-gas is treated with oxygen-¦ 10 containing gas at temperatures within -the range 100 and ¦ 700C in contact with a car-rier-supported ca-talyst containing barlum aluminate as the carrier and oxides of copper, manganese and nickel and, if desired, cobalt as the catalytically active ingredien-ts.
This process is not fully satisfactory, however, in using an oxidiæing atmosphere which does not promote the decon-tamination of the off-gas of internal combustion engines from nitrogen oxides oeing equally contained therein. To ensure an effective ca-talytic removal of ni-trogen oxldes from o.~-gas, i-t is necessary for -the catalyst -to be contacted with a gas stream which has ~ reducing properties or is at least neutral (U.S.Paten-t ¦: 2 924 504) The present invention now provides a process for removlng hydrocarbons.from the off-gas of internal combustion engines, under non-oxidizing conditions. The process of -the present invention comprises more particul~rly reacting the hydrocarbons with steam and/or carbon dioxide a-t temperatures within the range 200 and 800~ in con~act with an inert carrier-supporte~ catalyst . , .

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having catalytically ac-tive o:~lles of copper, manganese and nickel applied to the carrier, and thereby transiorming -the hydrocarbons to carboYl monoxide and hydrogen. ;~
Further PL e~erred ~eatures 3f the pl~esent process provide:
a) for th~ hydrocarbons -to be reacted at temperatures within the range 300 and 600C;
'~J~ for th~ of~-gas to be cont~cted -~tith the catalyst at a spatial velocity within -the range 5000 and 200 000 l per hour per l o~ catalyst;
c) for the catalyst carrier to have -the individual oxides o~ copper, manganese and nickel applied thereto in a ratio by weight within the ranse 0.1 and 1;
d) for the individual elements to be applied to the carrier in a ratio by weight o~ 1:1:1, e~ ~or the inert carrier to consist of alumina, splnel t~ , or cordierite;
f) ~or the carri.er to be a honey~comb carrier;
g) for the ca~rier to consist o~ pellets having a diameter ~ 20 within the range 2 and 5 mm;
h) ~or the use of` a catalyst made by heating the carrier to temperatures within the range ~00 and 400C;
impregnating the carrier by dipping it for a period withirl the range 20 and 40 minutes in a hot aqueous solution of copper, manganese and nickel nitrates;
; removing liquid adhering super~icially to the carrier by shaking; drying the carrier so impregnated with -;
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the nitrates o~ the catalytically active elements for a period within the range 1 and 2 hours at temperatures wit~in the range 105 and 130~C;
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decompocia~ -t~i~ nitrates to oxides by gladually heat.ing t}le carr:ie-r to -t~ pera-tures within the range 350 arld 4~0 C; calcining the carrier so co~r~red wi.th . the o~ides lor a perlod ~ithin the range 5 and 15 ho~rs to temperat-lres w.i-thin -the range 700 and gooc;
and ac-tivating the carrier for a period ~,~itnin the ran~e 1 and 3 hours at temperatures within the range 300 and 500C by means o a hydrog-n/nitrog~n-mixture;
i) for the use of a catalyst made by first dipping the carrier for a period within the range 20 and 40 minu-tes in an aluminum salt solution and tn~n impregnating it with the copper, .nanganese and nickel nltrate solution; removing liquid adhering superficially to the carrier by shaking; drying the carrier having the aluminum salt applied thereto for a period withi~
the range 1 an~ 2 hours -to tempera~ures within -the range 105 and 120C and gradually heating it -to temperatures within the range 350 and 500C; and calcining the carrier having aluminum o~ide applled thereto for a period within the range 3 and 10 hours ... . . ...
at temperatures ~ithin -the range 500 and 800C;
j) for aluminum nitrate to be used as -the aluminum salt;
k) for alumin~m hydroxychloride to be used as the aluminum salt;
l~ for the use of a catalyst made by ~irst dippin~ the `~
carrier for a period within the range 20 and 40 minutes in an aqueous suspension of finely divided ~ alumina and then impregnating it ~ith the copper, ; manganese and nickel nitrate solutlonj remo~ing liquid adherinO~ super~icially to the carrier by shaking;
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drying the carrier having t.le alu.-nina applied thereto for a period within the ran~e 1 and 2 hours at tem~eratures within the range 105 and 120C; gradually heating the carrier to tempera-tures w.ithin the range ~:
350 and 50GC and maintaining it within that ~.
remperature range for a period with~.n the range 3 . and 10 hours. .
The process o~ the present inven~icn, wher ein advantage is taken of those reactions which occur between .
hydrocarbons and steam and/or carbon dioxi~e in contact .~ .
with mixed oxide catalysts of copper~ manganese and nickel, enables hydrocarbons to be removed from off-gas ~:
being free or substantially free frorn oxygen. Resulting carbon monoxide and hydrogen are delivered to an oxidation ~-.
catalyst placed downstream of the mixed oxide cat~lyst, admixed wit'n a.r and burnt. Needless to say it is .necessary for a do~mstream catalyst to be used to ensure . the oxidatlon of carbon monoxide contained from the onset - - -in the off-gas of internal combustion èngines. ..:
. The catalysts used in the process of the present ~inve.ntion also enable nitrogen oxides to be removed catalytically from the off-gas of internal combustion .
engines, under reducing conditions... . . . -~ . In each cf the following Examples~ a-gas containlng ::~ .O.1 % by volume of n-hexane, .
10 % by volume of H20, :
10 % by volume of C02, - . . .

2 % by volume of C0, - .
0.2 % by volume of 2~
0.3 % by volume of N0, . ... -: 5 :.

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the balance being N2 was reac-ted as described herein i.n contact Wit}l a catalyst con~aining the catalytically active incredients Cu:Mn:Ni in the atomlc ratio of 1:1:1. The gas was heated in each particular case to the lest temperature and contacted with the catalyst at a spatial velocity of 24 000 liter per hour per liter of catalystc The residual con~entratlon of ~0 and n-hecane, res~ectively, in the reacted gas was identiYied and the conversion in % of ~-these two substances was calculated therefrom .
The temperatures referred to in the Examples are those at which 50 and 90 %, respectively, of NO and n-hexane, respectively, were found to have been converted (U50 hex; UgO hex; U50 NO; UgO NO) The gas composition indicated hereinàbove is 'ypical ; of an exhaust gas of an internal combustion engine, with an appropriate ratio of fuel to air.
EXAMpLE 1: (Comparative Example) .. . ..
Preparation of_catal~st 20~ A~ equimolar blend of copper, manganese and nickel nitrabes was kneaded at 100C to give a viscous homogeneous mass, which ~as dried for 1 hour at 110C. Following -this, .
the mass was heated to 400C to decompose the nitrates.
The resultin~ mass was pulverized and -triturated lJIith a ~ 1 % solution of meth71cellulose (TYLOS ~ to obtain ; ~ material suitable for treatment in an extruder. The : , ; extruded strands were calcined for 15 hours at 800C and finally ~ctivated for 2 hours at 450C with 5 % by volume of hydrogen, in a hydrogen-nitrogen atmosphere.
Cata~st proPerties: Specific surface area (~ET):

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1 7 m2/g vol~le of ~ores~ 0.3 cm~/~
Convi~y~-:Lo-rl U5G hex 7 U50 N0 3~0 C rJc~o N0 410 C
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EX~IPLE 2: (Comparative Example) Pre~aration of catal~rst ~ = =
An equimoIar blend Gf co~per, m~ngane~e a-nd nicl~el nitrates and an iden-tical quantity of ~-aluminum hy~roxide . .
(particle size less th~ m) were kneaded under vacuum ``
hile water was added toobtainaviscous paste, which was dried for 2 hours at 110C. The dry paste was heated to 400C to decompose the nitrates. The resulting mass ~ra~
pulverized aIld a sieve fraction thereof, consisting of particles with a size of less -than 200 ~m, was made into a paste with the use of a 1 % TYLOS~solution, and -the paste was del vered to an extruder. The e~truded strands ere heated to 1250C while the temperature was increased h; ' ' at a rate o~ 100C per hour, and maintained at that 20~ temperature for 15 hours. Following thii~, the catalyst t~as activated fo~ 2 hours at 450C with 5 % by volume o~
hydrogen, i~ a hydrogen-nitrogen atmosphere.
Catalyst pro~erties: Specific surface area (BET): 1.0 m2/g Volume of pores: O.Z9 cm3/g ConVersl-n-- U50 hex 7 U ~2~ir U 7~;or 50 NO ' ~ ' `' 90 NO (~ v .

EXAMPLE 3: (Comparative~Example)

3~ SPERALITHER (a product of Pechiney-St.Gobain), i.e. .~

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loosely agC~regated carrier mate~rial was heated to ~50 dipped in Q hot consen-trated equinlolar aqueous solution of ccpper, manganese and nickel rîitrates and allowed -to remain therein for 30 mlnutes.Liquid which adhered superficially to the loosely aggregated material was removed by shaking~ ~he impregnated material was dried for 1 hour at 110C and heated to 400C while increasing the temperature at iniervals o~ 50C/hour. The-carrier material so covered with the metal oxides was calcined for 10 hours at 800C and the resulting catalyst was finally activated for 90 minutes at 450C by means of 5 % by vol~e of hydrogen, in a hydrogen/nitrogen atmosphereO
Catal st pro~erties: Specific surface area (BET): 10.0 m2/g Volume of pores: 0.41 cm3/g Conve s r- U50 hex 520 C UgO hex 700 C
- ~U50 N0 2~C U : 330C
: ~ ' . ' . '' , ExAr~PLE 4: (Invention) Pre~aration of catal~st ,: , .
Honey comb material ~ased on aluminum oxide (a .
p~oduct o~ FeldmUhle AG, Plochingen) was heated to 350C, dipped in a solution of aluminum hydroxychloride (170 g Al203/kg solution) and allowed to remain therein for 40 minutes. Solution which ad~ered superficially to the honey conlb material was removed therefrom by shaking, the carrier was dried ~or 2 hours at 110C and~heated to 450~ hile increasing the temperature at intervals of ; i 50C per hour. Following this, the honey comb carrier was calcined for 6 hours at 700C. It~ wèight w~s ~ound to :

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have been increased by 7.~ %.
The honey comb carrier so treated was heated to 30VC 5 dipped in an equimolar hot concentra-ted aqueous solution of copper~ manganese and nickel nitrates and allowe~ to remain therein for 40 minutes Liquid contained ln the passageways of the honey-comb oarrier was removed by snaking and the impregnated carrier was dried for 1.5 hours a-t 115C. Following this, it was gradually heated to 400C, while increasing the temperature at intervals of 50C/hour, to decompose the nitra-tes. The honey comb carrier so covered with the metal oxides was finally calcined for 6 hours at 800C and ac~ivated for 2 hours at 400C with 5 % by volume of hydrogen, in a hydrogen nitrogen-atmosphere.
_talyst pro~verties: Content of copper, manganese and nickel oxides: 13.5 weight %
Specific surface area (BET): 7.3 m2/g Volume of pores: 0.17 cm3/g ConverSin: U50 hex U 580C
~50 N0 : 215 C Ugo NO : 320 C

EXAMPLE 5: (Invention) Preparation of catalys-t ; Honey comb material based on cordierite (Corning Glass, New York) w~s heated to 400C, dipped in a 50 % aqueous solution of Al2(0H)5Cl and allowed to remain therein for 30 minutes. Liquid which adhered superficially to the honey ., .
comb material was removed therefrom by shaking, the carrier was dried for 1 hour at 120C, and heated to 500C while increasing the temperatu!~e a~ intervals of 100C/~our, .. ..
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wh?r~y the aluminu?. hydro-~Yychlorid~ -was decompo~e~ to alumin~lm oxi~e. Follcl.~ing this, the honey oomb material was calcirled ~or 5 hours at 800C.
The honey comb material so treated was heated to 400C, dipped in an equimolar hot concentrated aqueous solution of copper, manganese and nickel nitrates and allowed to remain therein for 30 minutes. Liquid contained in +he passaOe~rays of the 'noney comb carrier w~s removed by shaking and the impregnated carrier was dried for 1 hour at 130C. The nitrates were decomposed by gradual heating to 450C, whlle increasing the temperature at intervals of 60C/hour. The honey comb carrier so covered with metal oxides was calcined for 10 hours at 750C and finally activated for 3 hours at 300C with 5 /0 by volu~e of hydrogen, in a hydrogen/
nitrogen-atmosphere.
Catalyst pro~ert_es: Content of copper, manganese and nickel oxid~s: 17. 5 waight %
Specific surfac:e area (BET): 5.4 m2/g Volume of pores: 0.22 cm3/g - ConverSln: U50 hex 3 90 hex : 520~C
U50 N0 255 C UgO N0 : 370C

E~AMPLE 6 (Invention) Prepara-tion of catalyst: ~ - - i Honey comb material the same as that used in Example 5 was heated to 350C, dipped in an aqueous suspension of -~
finely dispersed alumina (6.9 g Al203/100 g suspension) ;~
and allowed to remain therein for 30 minutes. Suspenslon ; 30 which adhered superfieially to the honey com~b carr.ier was .~ .

~P' ~ ' ' ' : ~ . ,.' :. , removed therefrom by shaking and the carrier was dried f`or 1 . 5 h at 110C. The dry honey comb carrier was heated.:
to 400C, while the -temperature was :increased at interv~ils~: .
of 80C/h~ and main-tained a-t th2t temperature for 5 hours~
. The carrier was impregnated wi-th copper, manganese and nickel oxides and the ca-talyst was activated i.n the :
manner described in Example 5. . .~:
, Ca~al~st properties: Content of copper, manganese and nickel . oxides: 18.4 weight % - : ;
10~ . Specific surface area (BET): 5.9 m2/g Volume of pores: 0.21 cm3/g ..
ConverSi~n: Ur~o hex U90 hex : 570 C . -U50 N0 : 230C U90 N0 : 280 C -' E~AMPI.E 7: (Inven~tion) ~ Preparation of catalyst : Honey comb material based on cordierite ~Amsricanl ; :
Lava, Tennessee) wa3 covered wi-th an alumina layer in the manner described in Example 5. The cataIytically ac-tive ..
ingredients were applied to the carrier and -the cata].yst ~: was activated in the manner described in Example 5.
Catalyst proDertiss: Content of copper, manganese and nickel oxides: 14.0 weight % :.
Spec~.~ic surface area (BET): 6.6 m2/g '.;
Volume of pores: 0.18 cm3/~
Con~ersion: U o h : 4~0C U90 h~ : 520C ;~
- 5 ex ~x -50 N0 255 C U90 N0 3 ~ ;

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~ EXAMPLE 8:~(Invention) ' Prep~ration of catal~st - ;. .

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H~ney comb material the same as that used in Example

4 was heated to 400C, dipped in an aqueous solution of aluminum nitra-te (68 g Al203/kg solution) and allowed to remain therein for 20 minu-tes. Solutlon which adhered superficially to -the honey comb ma-terial was removed -there~rom by shaking, the carrier was dried ~or 2 hours at 120C, then heated -to 500C, while the temperature was ' increased at intervals of 60C/h, and maintained at that -~' temperature for 5 hours. The weight of the honey comb material so treated was found to have increased by 10.8 weight %. ,' The catalytically active ingredients were applied to the carrier and the catalyst was activated in the "
manner described in Example 4. , , '~ Catalyst ~oper-ties: Content of copper, manganese and nickel oxides: 23.0 weight % , Specific surface area (BET): 5.2 m2/g `, Volume of pores: 0.17 cm3/g '' ConverSin: U50 hex UgO hex : 580C
U50 N0 215 C UgO N0 3 ;',~ ' EXAMPLE 9: (Invention) Prepara-tion of cata~st ~ -' ~ a-aluminum hydroxide was rapidly blended with 5 weight,% of ben-tonite, the blend was admixed with a 1 %
TYL05 ~ solution and the whole was made into pellets on ` a granulating plate. A frac-tion consis-ting of pellets ; having a diameter within the range 4 and 5 mm was heated irst to 400C, while the temperature was increased at ~- 30 in-tervals of 50C/h, then to 1450C, while the temperature 1 ~ ~
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was increased a-t intervals of 100C/h, and maintained at -- -that higher temperature for 17 hours. The pellets so treated had a diameter of 2.5 mmand a s-trength of 5 kg/
pellet.
A-t a temperature o~ 350 C, the pellets were dipped in a hot (90C) concentrated aqueous solution of an equimolar blend of copper, manganese and nickel nitrates and allowed to remain -therein for 30 minutes. Solution in excess was poured off, the pelle-ts were heated to 400C, 10 ~ while the temperature was increased at lntervals of 100C/
h, to decompose the nitrates. Following this, the tempera-ture was increased to 800C and maintained for 15 hours.
The impregnated pellets were finally activated for 2 ~ - hours a-t 450C with 5 % by volume of hydrogen7 in a~
" hydrogen/nitrogen-atmosphere.

Catal~st properties: Specific surface area (BET): 5.3 m /g Volume of pores: 0.31 cm3/g Conversion: U50 hex 480 C UgO hex 610 C
50 MO : 275 C UgO I~O 390C

EXAMPLE 10- (Inventior~) ~ : . ...... ........ . .
'g~ Preparation of catalyst 199 parts o~ ~-aluminum hydroxide (99.7 weight %
Al(OH)3; 80 ~O particles with a size of less than 0,5 ~m;
specific surface area 7 m2/g) and 1 part of aluminum oxide (99.5 weight % Al203; mean particle size: 0.6 ~m;
speciflc surface area: 8.5 m2/g) were intimately blended by thorough agitation in an aqueous suspensior.. The :;:, suspension Was dried at 110C, the resulting pulverulent mass was made into a pas~;e with a 1 % TYLOS ~ sol~tion 1~: , . . .

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and extruded into strand.s having a diameter of 5 mm. The strands were out while moist to s-trand sections 5 mm long, which were dried at 100C and -then hea-ted -to 400C
while increasing the temperature a-t intervals of 100C/h.
The temperature was finally increased to 1400C and the strand sec-tions were maintained at that temperature for 17 hours, whereby their diameter was reduced to 3.2 mm.
The strand sections so treated had a strength of 2.3 kg mm.
The catalytically active ingredients were applied to the carrier and the catalyst was activated in the manner described in Example 9.
Catalyst properties: Speci~ic surface area (BET): 4.8 m2/g Volume o~ pores: 0.24 cm3/g ;-Conversion: U50 hex 470C UgO hex 500 C
50 N0 : 220 CUgO N0 : 280C.
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Claims (9)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for removing hydrocarbons from the off-gas of internal combustion engines, which comprises reacting the hydrocarbons with a gaseous compound containing oxygen chemically bonded therewith and being selected from the group consisting of steam and carbon dioxide at temperatures within the range 200 to 800°C in contact with a carrier-supported catalyst comprising an inert oxide selected from the group consisting of alumina, spinel or cordierite as its carrier, and a mixture of oxides of copper, manganese and nickel as its active ingredients, said individual elements being applied to the carrier in a ratio by weight in the range of 0.1 to 1; and contacting said off-gas with said catalyst at a spatial velocity within the range 5000 to 200 000 liter per hour per liter of catalyst so as to transform the hydrocarbons to carbon monoxide and hydrogen.

2, The process as claimed in claim 1, wherein the individual elements are applied to the carrier in a ratio by weight of 1 : 1 : 1.

3. The process as claimed in claim 1, wherein the carrier is a honey comb carrier.

4. The process as claimed in claim 1, wherein the carrier consists of pellets having a diameter within the range 2 to 5 mm.

5. The process as claimed in claim 1, carried out in contact with a carrier-supported catalyst having been produced by heating the inert oxide selected from the group consisting of alumina, spinel or cordierite to temperatures within the range 300 to 400°C, impregnating the inert oxide by dipping it for a period within the range 20 to 40 minutes in a hot aqueous solution of copper, manganese and nickel nitrates; removing liquid adhering superficially to the inert oxide by shaking; drying the inert oxide so im-pregnated with the nitrates of the active elements for a period within the range 1 to 2 hours at temperatures within the range 105 to 130°C; decomposing the nitrates to oxides by gradually heating the impregnated inert oxide to temperatures within the range 350 to 450°C; calcining the inert oxide so covered with said oxides for a period within the range 5 to 15 hours to temperatures within the range 700 to 900°C; and activating the calcined inert oxide covered with said oxides for a period within the range 1 to 3 hours at temperatures within the range 300 to 500°C by means of a mixture of hydro-gen and nitrogen.

6. The process as claimed in claim 5, carried out in contact with a carrier-supported catalyst, which is produced by dipping said inert oxide, prior to its impregnation with the copper, manganese and nickel nitrates, in aqueous suspension of finely divided alumina for a period within the range 20 to 40 minutes; removing liquid adhering superficially to the inert oxide by shaking; drying the inert oxide having the alumina applied thereto for a period within the range 1 to 2 hours at temperatures within the range 105 to 120°C; gradually heating the inert oxide so covered with said alumina to temperatures within the range 350 to 500°C and maintaining it within that temperature range for a period within the range 3 to 10 hours.

7. The process as claimed in claim 5, carried out in contact with a carrier-supported catalyst, which is produced by dipping said inert oxide, prior to its impregnation with the copper, manganese and nickel nitrates, in an aluminum salt solution for a period within the range 20 to 40 minutes; re-moving liquid adhering superficially to the inert oxide by shaking, drying the inert oxide having the aluminum salt applied thereto for a period within the range 1 to 2 hours at temperatures within the range 105 to 120°C and gradually heating it to temperatures within the range 350 to 500°C; and calcining the inert oxide having aluminum oxide applied thereto for a period within the range 3 to 10 hours at temperatures within the range 500 to 800°C.

8. The process as claimed in claim 7, wherein the aluminum salt used is aluminum nitrate.

9. The process as claimed in claim 7, wherein the aluminum salt used is aluminum hydroxichloride.