Catalysts for Low-Temperature Oxidation of Ethene - American

Chapter 25

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Catalysts for Low-Temperature Oxidation of Ethene Linda M. Parker and John E . Patterson The New Zealand Institute for Industrial Research and Development (Industrial Research Limited), P.O. Box 31-310, Lower Hutt, New Zealand

The focus of this work was to develop a catalyst for complete oxidation of volatile organic contaminants at temperatures less than 100°C, one application being the removal of ethenefromfruitstorage areas. A wide range of catalysts were surveyed using a mini-reactor coupled to a mass spectrometer and a total hydrocarbon detector. For 300 ppm ethene, 0.6% O in N with a volume space velocity of 60000 h , all the oxide materials tested reacted at >300°C. Pt asbestos and Pd alumina gave 50% conversion at 145°C, but for Pt and Pd on zeolites this was ~100°C. HZSM-5 also behaved as an oxidation catalyst with 100% conversion of ethene at 200°C. Reactivity of PtCsNaY(T) remained constant after conversion of 5 g ethene/ g catalyst. 2

2

-1

This work describes the initial development o f a l o w temperature oxidation catalyst for the removal of ethene from fruit storage areas. Ethene is a gaseous plant hormone that causes fruit ripening, and removal to less than 0.03 p p m is important to preserve fruit i n an unripened state. The catalysts must also function with reduced oxygen concentrations and i n the presence of water. F o r example, i n kiwifruit cool stores the atmosphere is controlled at 2% oxygen and 5% carbon dioxide with 100% humidity at 0 ° C . For catalytic oxidation of volatile organic contaminants ( V O C s ) , large volumes of air must be heated to the reaction temperature of the catalyst. T o improve efficiency heat exchangers can be used to heat the incoming air to the catalyst reaction temperature. Commercial units are available for ethene removal from fruit coolstores which use this method with a supported platinum catalyst held at ~ 2 7 0 ° C (7). The contaminant could also be removed by sorption at room temperature followed by desorption and catalytic oxidation of the concentrate (2) at a higher temperature. A third alternative is to develop a catalyst which reacts at as l o w a temperature as possible. Development of a low temperature oxidation catalyst would

0097-6156/94/0552-0301$08.00/0 © 1994 American Chemical Society

ENVIRONMENTAL CATALYSIS


302

enable a simpler and less expensive reactor system that could be used i n transportation containers and shop storage areas. Other applications are envisaged for low temperature oxidation catalysts, such as improvement o f quality of air inside buildings by removal o f organics, such as formaldehyde, released by synthetic materials. The "ultimate" goal is a catalyst which w i l l completely oxidize all V O C s i n a gas stream at its inlet temperature (3). F o r this highly active, non specific catalysts are required. The temperature at which oxidation occurs depends upon both the reactant and the catalyst, with most reactions recurring above 2 0 0 ° C , well above the "ultimate" goal (3). Only a few heterogenous oxidation reactions have been reported to occur below 5 0 ° C (eg 3,4*5). Both metal oxides and supported noble metals are useful oxidation catalysts. M e t a l oxides i n which the metal can assume more than one valence state, are p-type semi-conductors, and produce a surface on which oxygen w i l l readily chemisorb. Oxides o f V , C r , M n , Fe, C o , N i and C u are typical examples. M e t a l oxides have a lower activity than noble metal catalysts but they have greater resistance to some poisons, especially halogens, A s , P b and P . The noble metals remain i n their reduced, metallic state under most conditions and provide surface sites for dissociative adsorption of oxygen. Only Pt and P d are used i n practical systems because o f their stability and cost. Reaction occurs either between adsorbed oxygen and a gas phase reactant, or with both oxygen and the reactant sorbed on the surface. In most noble metal oxidation catalysts the metal is deposited on a high surface area support such as alumina (6,7,8,9), silica (5) and zirconia (10). Zeolites are also suitable supports, but have not been widely used for practical oxidation catalysts. Their main applications are i n synthesis reactions such as the conversion of alkanes to aromatics (11,12,13). The use of zeolites as substrates for oxidation catalysts would give the following advantages over simpler substrates: 1.

2. 3.

There are a wide range of zeolite structures available with variable aluminium concentrations, enabling zeolites with specific properties to be selected as catalyst supports. They have high internal surface areas and can preferentially sorb reactants. They enable much greater control over metal particle size distribution than do other supports (14,15) because the restricted dimensions i n zeolites isolate encaged metal particles from each other and stabilise small metal clusters. Addition o f cations such as C a , M g * , C u , N i , C r * and M n alter the mechanism of noble metal particle formation during catalyst preparation by blocking the small cages of the zeolite (16) or impeding the migration and coalescence o f primary particles. This also assists i n retaining a greater dispersion o f noble metal i n the product (17). Additional cations (including H ) can be incorporated to alter catalyst reactivity. F o r example, the presence of protons (Bronsted acid sites) gives additional reactions characteristic of zeolite acid sites (18). F o r palladium zeolites it is suggested that complexes of the type [ P d H ] are formed which greatly increases the rate o f some reactions (1920). 2+

4.

2

2 +

2 +

2 +

+

z+

n

z

25.

PARKER & PATTERSON

Low-Temperature

303

Oxidation of Ethene

Oxidation catalysts for ethene have been developed for partial oxidation to ethene oxide. These are silver sponge (22) or silver on a support such as γ Α 1 0 (22), and they are typically operated at >230°C. A zeolite impregnated with silver (30% A g ° C a A ) was reported to give an ethene conversion and yield of ethene oxide comparable to other catalysts (23). Complete oxidation of ethene was reported over vanadium oxide catalysts between 440 to 500°C (24) but no other references to l o w temperature, complete oxidation of ethene have been found. In this work a wide range of possible catalysts for ethene oxidation have been surveyed. A mini-reactor coupled to a mass spectrometer and a total hydrocarbon detector enabled the oxidation temperature o f ethene for each catalyst to be determined. The most promising catalysts appeared to be noble metal supported on zeolites. These were then tested under constant reaction conditions. The effects o f reduced oxygen concentration and increased humidity were determined to obtain an indication o f catalyst reactivity i n fruit coolstore atmospheres. 2

3


2+

Experimental P r e p a r a t i o n of Catalyst Samples. Zeolites Used. H Z S M - 5 (prep #816) was synthesised as described i n a patent application (25) and contained 1.48 wt % A l . Silicalite (prep 3, 7/4/86) was synthesised as described by Parker et al. (26) with 0.14 wt % A l . Zeolite Y (Linde Y , S K 4 0 , lot no. 9680801014) (8.5 wt % A l ) and zeolite 5 A (Linde batch #1457220) were obtained from U n i o n Carbide, U S A . Zeolite Y Got #ST1192) was obtained as pellets containing 25 parts alumina to 100 parts zeolite from Tosoh, Japan and contained 15.8 wt% A l (including the binder). Nomenclature of Ion E x c h a n g e d Zeolite samples. The sample names are given with the metal then the cations preceding the zeolite name. F o r example, P t C a N a Y ( L ) " represents a sample for which C a then P t were exchanged into N a Y zeolite. The P t was then reduced to the metal before catalysis. The " L " designates a sample of Linde Y and a " T " designates a sample o f zeolite Y from Tosoh. M

2 +

+

2+

2+

I o n E x c h a n g e of Zeolites. The zeolites were first exchanged i n a 0.5 M of the appropriate salt solution, then filtered and washed. This was followed by exchanging two times i n saturated solutions of either P t ( N H ) C l or P d ( N H 3 ) C l solutions containing excess ammonia. The zeolite Y samples were heated on a steam bath to increase the degree of exchange. The samples were filtered, washed and dried. 3

4

2

4

2

Analysis o f Zeolites. Analysis for Pt was carried out by digestion i n hot aqua regia followed by A A spectroscopy. The other cations were analysed by H F / H C 1 0 digestion followed by A A or A E spectrosopy.

4


304

O t h e r Catalysts. AlINi Hydrotalcite: was prepared by heating 0.01 mole A 1 ( N 0 ) . 9 H 0 , 0.02 mole N i ( N 0 ) . 6 H 0 , 0.05 mole N a O H and 0.15 mole Ν 3 ^ 0 i n 35 m l H 0 at 80°C i n a sealed container for 2 days. Mixed iron oxide: was prepared by heating 0.01 mole A 1 ( S 0 ) . 1 8 H 0 , 0.02 mole F e S 0 . 7 H 0 and 0.1 mole N a O H i n 35 m l H 0 at 80°C i n a sealed container for 2 days. The crystalline product was identified by X r a y Diffraction as F e ^ and F e ^ . Cerium oxide: was a laboratory grade reagent. Unsupported P-V-0 salt: A mixture of phosphorus and vanadium salts were prepared following the method of Centi et al.(27). The solution was evaporated then calcined at 4 0 0 ° C . P-V-0 on zeolite Y: This was prepared following the method o f Centi et al.(27). This was filtered without washing and dried at 5 0 ° C for 1 h i n air. Platinum and Palladium on Iron Sand Ceramics: Porous iron sand ceramic (28) was ground then: A . 0.01 g P d ( N H ) C l dissolved i n 1 m l water was added to 0.20 g ground ceramic, mixed then dried overnight under vacuum. B . ~0.2 g of bright platinum (Matthey P B V 1 5 8 ) was mixed with 0.23 g ground ceramic. Pt asbestos: contained 5% Pt and was supplied by Hopkin and Williams. Pd on activated alumina: contained 10% P d and was supplied by F l u k a A G Buchs SG. Pd on charcoal: contained 10% P d on activated charcoal and was supplied by M e n u A G Darmstadt Silver sand: was prepared i n this laboratory with silver deposited on silica sand using a method for preparation of mirrors by silver deposition. 3

3

2

3

2

2

3

2

4


4

2

3

2

2

3

4

2

Catalyst pretreatment. The metal ion exchanged zeolites were pretreated before testing to obtain the reduced metal. The sample was reduced by heating from r o o m temperature at 10°C/min. to 300°C i n a 1% i y A r gas stream and holding for 1 hour. The sample of liquid bright Pt on iron sand was reduced by gently heating over a flame. Catalyst testing M e t h o d . The mini-reactor system for catalyst testing is shown i n figure 1. The catalyst (-10 mg) was held i n a glass tube by silica w o o l to give a bed 1.3 m m diameter and ~7 m m deep placed i n a temperature controlled furnace. The sample tubes could be readily interchanged and the packed sample retained for further study. F o r initial experiments the gas flow rate was controlled at 10 ml/min by a needle valve. In later experiments, the gas flow rate was more precisely controlled by a fixed capillary leak at - 1 ml/min. The reacted gas was analyzed by a D y c o r M A 1 0 0 M mass spectrometer and/or a total hydrocarbon detector (29) which was very sensitive for traces of ethene. Sample temperature, output from the total hydrocarbon detector and mass spectra were recorded against time using speciality software (30). Experiments were carried out by heating the sample to 3 0 0 ° C then cooling at 12°C/min, to reduce effects of sorbed ethene. F o r catalysts that reacted at less than 100°C ethene was also sorbed during cooling, obscuring the minimum reaction temperature. T o determine reaction temperatures, stepping experiments were carried out i n which the catalyst was held at constant temperature until a steady state was reached.

25. PARKER & PATTERSON

Low-Temperature

305

Oxidation of Ethene

Results a n d Discussion Tables I, Π and ΙΠ show the results of the catalyst survey under three different sets of conditions. The results from the cooling experiments can be used to rank the catalysts i n order of activity. Lowering the mass flow rate of ethene reduces the observed reaction temperatures, with the lowest temperatures observed for 140 ppm ethene at 6000 h" (Table ΙΠ). This results i n physisorption of ethene on the zeolites partially obscuring most reaction temperatures i n the cooling experiments. Therefore stepping experiments were also carried out. Although differences i n measured temperatures were observed, both the cooling and stepping (steady state) experiments ranked the catalysts i n the same order of activity. The only exceptions were the copper exchanged zeolites which sorbed ethene very strongly. Cerium oxide was the only oxide that reacted with ethene below 3 0 0 ° C (Table I). Figure 2 shows the results obtained with a sample of ground iron sand ceramic where no reaction was observed. This is effectively a "blank run" and shows that no measurable reaction occurs on the reactor surfaces under the experimental conditions. The silver catalysts tested showed low reactivity, with silver on silica sand reacting above 300°C. Silver deposited on zeolite 5 A ( A g C a A ) strongly sorbed ethene giving a low T of ~60°C. However, the carbon dioxide ion signal showed that the oxidation reaction started at ~ 1 5 0 ° C but was not complete by 300°C. For Pt on asbestos (figure 3), reaction of ethene is clearly shown by a drop i n ethene and oxygen concentrations and the total hydrocarbon detector signal. A corresponding increase i n carbon dioxide concentration occurred, with no other products observed. Increasing the oxygen concentration i n the gas stream decreased the reaction temperature, with T dropping from 145°C to 105°C (compare Table I and Table Π). The P d on charcoal catalyst was not effective above 2 0 0 ° C because the charcoal oxidised before oxidation of ethene occurred. P d on alumina (figure 4) was slightly more reactive than Pt on asbestos, but decreased i n activity with increasing oxygen content ( T rose from 155 to 165°C and T rose from 156 to 190°C). The carbon dioxide signal increased slowly with temperature after the ethene and T H D signals declined, suggesting that partial oxidation products may have also formed. Some Pt and P d zeolite samples showed greater reactivity than Pt on asbestos and P d on alumina. Distinct differences were also observed between zeolites loaded with Pt and those with P d . For example, for P d on zeolite Y , addition o f C a cations increased the ethene reaction temperature but for Pt on zeolite Y the reverse occurred For P d C a N a Y ( L ) increasing oxygen and decreasing ethene concentrations i n the gas stream also increased the reaction temperature, similar to the effect observed for P d on alumina (see figures 5 A and B ) . F o r P t C a N a Y increasing the oxygen concentration greatly decreased the reaction temperature i n a similar manner to Pt asbestos (see figures 6 A and B ) . These differences imply different ethene reaction mechanisms for Pt and P d catalysts, with perhaps only partial oxidation occurring over P d catalysts. Therefore the Pt catalysts were investigated i n more detail as catalysts for complete oxidation are required.


1

1 0 %

5 0 %

5 0 %

1 0 0 %

2 +

A series of catalysts were prepared with different cations i n a similar manner and tested under the same conditions. The ethene oxidation results, ranked i n order


306


TOTAL H Y D R O C A R B O N DETECTOR

CATALYST THERMOCOUPLE

CAPILLARY R E A G E N T GAS MASS

SPECTROMETER

Figure 1. A schematic diagram of the mini-reactor system used for catalyst testing.

50

100 150 200 temperature (°C)

250

Figure 2. Results for 300 ppm ethene and 0.6% oxygen i n nitrogen over i r o n sand ceramic at 60000 h* . The total hydrocarbon detector signal ( ) and the mass spectrometer ion signals of ethene ( ) and carbon dioxide ( ) are shown versus the iron sand ceramic temperature. 1



Table I:

307

Low-Temperature Oxidation of Ethene

Summary of catalyst tests for 300 p p m ethene and 0.6% 0 i n N at a volume space velocity of 60000 h" . The catalysts were cooled at 12°C/min from 300°C. 2

2

1

Catalyst A l / N i hydrotalcite iron sand ceramic liquid bright Pt on iron sand ceramic P d on iron sand ceramic M i x e d iron oxides unsupported P / V salt P - V - 0 on Y silver sand treated with H Q cerium oxide AgCaA P d on charcoal CuNaY(L) PdCuHZSM-5 HZSM-5 PtNH4NaY(L) P d on alumina Pt on asbestos PdCaNaY(L) PdHZSM-5 PdNaY(L) CuZSM-5 PdCaZSM-5 PtCaNaY(L)

1"w% (THD)

1*5»% (THD)

>300 >300 >300 >300 >300 >300 >300 >300 -300 -60 >200 30?

>300 >300 >300 >300 >300 >300 >300 >300 >300 280 >200 45?, 150 180 176 150 146 145 136 106 103 47 105 100

140 166 27? 120 92 83 62 36 29 28? 40

(THD)

Two* (CO^

>300 >300 >300 >300 >300 >300 >300 >300 >300 >300 >200 >300

>300 >300 >300 >300 >300 >300 >300 >300 >300 >300 >200 >300

225 200 214 156 174 230 254 176 161 158 160

>300

235 200 200 230 235 >300 >300 216 215

Tio%» T and T are the temperatures, i n ° C , at which the given percentage o f ethene has reacted, as measured by the total hydrocarbon detector ( T H D ) . Tioo% ( C O ^ is the temperature above which the C 0 evolution is constant. 5 0 %

1 0 0 %

2

308


Table Π:

Summary of catalyst tests with 130 ppm ethene i n air at a volume space velocity of 60000 h" . The catalysts were cooled at 12°C/min from 3 0 0 ° C


1

Catalyst

PdCaNaY(L) Pt silicalite PdCuHZSM5 P d on alumina PtHNaY(L) PtCsNaY(T) Pt on asbestos PtCaNaY(L) PtCuNaY(L) τ

T

(THD)

^50% (THD)

(THD)

(CO,)

174 138 126 124 30 85 76 51 46

235 169 165 165 150 113 105 66 58

310 220 209 190 190 150 131 92 77

>300 -200 >300 >300 180 150 188 -100 115

τ

ιο%» 5o% and ιοο% the temperatures, i n ° C , at which the given percentage of ethene has reacted, as measured by the total hydrocarbon detector ( T H D ) . T ( C O ^ is the temperature above which the C 0 evolution is constant. m%

2

0

50

100

150

200

250

3θ8

temperature (°C) Figure 3. Results for 300 ppm ethene and 0.6% oxygen i n nitrogen over P t on asbestos at 60000 h" . The total hydrocarbon detector signal ( ) and the mass spectrometer ion signals of ethene ( ), oxygen ( ) and carbon dioxide ( ) are shown versus catalyst temperature. 1


25.

PARKER & PATTERSON

Table ΙΠ:

309


Summary o f catalyst tests with 140 ppm ethene i n N with 0.3% oxygen at a volume space velocity o f 6000 h" 2

1

Catalyst

Pt wt%

Na wt%

other cation wt

test type

% HZSM-5

0

-

0

CuZSM-5

0

-

-

P t H Z S M - 5 #2

0.25

0.06

0

Pt silicalite

0.08

0.07

0

PtBaNaY(L)

3.84

0.11

1.14 (Ba)

PtHNaY(L)

2.80

1.41

0

PtCuZSM-5

1.76

0.08

0.05 (Cu)

PtMgNaY(L)

2.93

1.32

0.45 ( M g )

PtCaNaY(L)

1.00

0.47

4.14 (Ca)

PtCsNaY(T)

3.17

1.11

0.01 (Cs)

P t H Z S M - 5 #1 cool: step:

0.71

0.10

0

step cool step cool step cool step cool step cool step cool step cool step cool step cool step cool step

(°Q (THD) >180 -20 >70 90 130 46 95 30 >100 55 90 20 >80 20

-

22 75 20

20

-

1"s»% (°Q (THD)

Two* (°Q (THD)

190 -20

200 -30 150 120 140 150 130 100 110 90 110 33 100 65 100 60 105 45 70 27 60

100 135 89 105 85 105 70 105 28 95 40 83 30 85 35 60 22

-

the catalyst was cooled from 300°C at 12°C/min the catalyst was held at a constant temperature until a constant ethene concentration was obtained



310

0


50

250

300

Figure 4. Results for 300 ppm ethene and 0.6% oxygen i n nitrogen over P d on a l u m i n a at 60000 h ' . The total hydrocarbon detector signal ( ) and the mass spectrometer ion signals o f ethene ( ) and carbon dioxide ( ) are shown versus catalyst temperature. 1

100 150 200 temperature (°C) Figure 5 A . Results for 300 ppm ethene and 0.6% oxygen i n nitrogen over P d C a N a Y ( L ) at 60000 h" . The total hydrocarbon detector signal ( ) and the mass spectrometer i o n signals of ethene ( ) and carbon dioxide ( ) are shown versus catalyst temperature. 1


25.

PARKER & PATTERSON

Low-Temperature

311

Oxidation of Ethene

temperature (°C) 1

Figure 5 B . Results for 130 ppm ethene in air at 60000 h* over P d C a N a Y ( L ) at 60000 h" . The total hydrocarbon detector signal ( ) and the mass spectrometer ion signals o f ethene ( ) and carbon dioxide ( ) are shown versus catalyst temperature. 1

0

50


250

30(9

Figure 6 A . Results for 300 ppm ethene and 0.6% oxygen i n nitrogen over P t C a N a Y ( L ) at 60000 h ' . The total hydrocarbon detector signal ( ) and the mass spectrometer i o n signals of ethene ( ) and carbon dioxide ( ) are shown versus catalyst temperature. 1


312


0

50

100

150

200

250

30(9

temperature (°C) Figure 6 B . Results for 30 ppm ethene in air at 60000 h" over PtCaNaY(L) at 60000 h ' . The total hydrocarbon detector signal ( ) and the mass spectrometer ion signals of ethene ( ) and carbon dioxide ( ) are shown versus catalyst temperature. 1

1

0

50

100

150

200

250

30(9

temperature (°C) Figure 7. Shows the effect of adding water vapour to 140 p p m ethene and 0.3% oxygen i n nitrogen reacting over PtCaNaY(L) at 6000 h" . The total hydrocarbon detector signal with out water vapour ( ) and with water vapour( ), and the mass spectrometer i o n signal of carbon dioxide without water vapour ( ) and with water vapour( ) are plotted versus catalyst temperature. 1


Low-Temperature

313

Oxidation of Ethene


of increasing reactivity, are shown i n Table ΙΠ along with the Pt and cation concentrations. The Pt concentration varied with different cations for the same zeolite. This may be an effect of the additional cation. The Pt concentration is also greater for zeolites with higher aluminium concentration as they have a greater cation exchange capacity. The lowest Pt concentration is recorded for silicalite, a l o w aluminium form of Z S M - 5 . The bulk Pt concentration was not the most important criteria for reactivity. F o r zeolite Y , there was no correlation of Pt concentration with reactivity. F o r Z S M 5, the best catalyst was produced with a Pt content of 0.71%. However, i n the silicalite sample with only 0.08% Pt a high proportion o f Pt must be held i n reactive sites as it was more reactive than a Z S M - 5 sample containing 0.25% Pt. H Z S M - 5 with zero Pt also functioned as an oxidation catalyst above 180°C. F o r this catalyst there was a very narrow temperature range between no reaction and compete reaction. A t less than 180°C no reaction occurred but above 2 0 0 ° C complete reaction occurred. E v o l v e d carbon dioxide increased as ethene decreased and no other products were observed. Catalyst reactivity appears to be influenced by the zeolite structure with Z S M 5 producing more reactive catalysts at lower bulk Pt concentrations than zeolite Y . For zeolite Y , the presence of an additional cation influences reactivity and perhaps dictates Pt uptake. However, there is no obvious correlation between cation charge or ionic radii of the additional cation and catalyst reactivity. M o r e detailed catalyst characterisation is required to determine how the cations have effected the nature of the reactive Pt particles. The C u exchanged zeolites had a very high sorption capacity for ethene, resulting i n low results for T and T i n the experiments where the sample was cooled at 10°C/min. A temperature stepping experiment for C u Z S M - 5 showed that no reaction occurred at 7 0 ° C , but complete reaction occurred from 150°C. Addition of Pt to this catalyst increased reactivity with 100% reaction occurring from 100°C. In fruit cool stores atmospheric conditions include l o w oxygen concentrations and - 1 0 0 % humidity at 0 ° C . Tables I and ΙΠ show that the catalysts function well at a low oxygen concentration with the reaction temperature depending upon the ethene mass flow rate. Water vapour has little effect on the reaction temperature as shown i n figure 7, where no significant difference was observed when water vapour was added into the gas stream by a bubbler at 20°C. Catalyst lifetimes for two catalysts were tested. P t H Z S M - 5 was held at 6 0 ° C i n a flow of 130 ppm ethene i n air at 10 ml/min for 3V4 days. Constant reactivity was observed over that period. F o r P t C s N a Y ( T ) , a gas stream of 1% ethene i n air was passed over the catalyst held at 100°C. After 66 h, 100% conversion was still occurring. The catalyst had converted 5 g ethene/ g catalyst with no loss of activity. 2 +

1 0 %

5 0 %

Conclusions W e have produced a range of ethene oxidation catalysts that are effective below 100°C i n the l o w oxygen and high humidity conditions typically found i n cool store atmospheres. These catalysts are the zeolites Z S M - 5 and Y , with Pt incorporated. Additional cations have a marked effect on the activity of zeolite Y with P t C s N a Y and P t C a N a Y being the best catalysts. However, no correlation with cation charge

314



or ionic radii was noted. More detailed study o f the catalysts is required to understand these effects and to prepare improved catalysts. W e have also shown that H Z S M - 5 , without Pt, functions as an oxidation catalyst for ethene. Copper exchange of both Z S M - 5 and zeolite Y results i n a zeolite that has a very high sorption capacity for ethene. C u H Z S M - 5 reacted with ethene at temperatures ~ 5 0 ° C lower than H Z S M - 5 .

Literature Cited 1. Catalytic ethene scrubbers are produced by ISOLCELL ITALIA SPA.39055 Laives (BZ) - Zona Industriale - Via Meucci, 7 2. Note in App. Catal.1991, 73, N4. 3. Spivey J.J.; Ind. Eng. Chem. Res., 1987, 26, 2165. 4. McCabe R.W.; Mitchell P.J. Appl. Catal. 1986, 27, 83. 5. Gonzalez R.D.; Nagai M. Appl Catal., 1985, 18, 57. 6. Skoglundh M.; Lowendahl L.O.; Ottersted J.-E. App. Catal. 1991, 77, 9. 7. Oh S.H.; Mitchell P.J.; Siewert R.M. J. Catal. 1991, 132, 287. 8. Loof P.; Kasemo B.; Andersson S.; and Frestad A. J. Catal. 1991, 130, 181. 9. Jackson S.D; Willis J.; McLellan G.D.; Webb G.; Keegan M.B.T.; Moyes R.B.; Simpson S.; Wells P.B.; Whyman R. J. Catal. 1993, 139, 191. 10. Hubbard C.P.; Otto K.; Gandhi H.S.; Ng K.Y.S. J. Catal. 1993, 139, 268. 11. Mielczarski E.; Bong Hong S.; Davis R.J.; Davis M.E. J. Catal. 1992, 134, 359. 12. McVicker G.B.; Kao J.L.; Ziemiak J.J.; Gates W.E.; Robbins J.L.; Treacy M.M.J.; Rice S.B.; Vanderspurt T.H.; Cross V.R.; Ghosh A. K. J. Catal. 1993, 139, 48. 13. Shipiro E.S.; Joyner R.W.; Khabib M.M.; Pudney P.D. J. Catal. 1991, 127, 366. 14. Jaeger N.I.; Jourdan Α.; Schulz-Ekloff G.; Kleine Α.; Ryder P.L. In Innovation in Zeolite MaterialsScience;Grobet P.J. et al. Editors, Elsevier, The Netherlands, 1988, p191. 15. Jaeger N.I; Jourdan A.L.; Schulz-Ekloff G. J. Chem. Soc. Faraday Trans. 1991, 87, 1251. 16. Feeley J.S.; Sachtler W.H.M. Catal. Lett. 1991, 9, 377. 17. Homeyer S.T.; Sachtler W.M.H. In Zeolites: Facts, Figures, Future, Jacobs P.A; van Santen R.A. Editors, Elsevier, The Netherlands, 1989, p975. 18. Chow M.; Park S.H.; Sachtler W.M.H, Appl. Catal., 1985, 19, 349. 19. Sachtler W.H.M.; Calcanti F.A.P.; Zhang Z. Catal. Lett., 1991, 9, 261. 20. Homeyer S.T.; Karpinski Z.; Sachtler W.M.H., J. Catal.,1990, 123, 60. 21. Yong Y.S.; Cant N.W., J. Catal.,1990, 122, 22. 22. Johnson D.L.; Verykios X.E. J. Catal.,1983, 79, 156. 23. Minachev and Isakov, In Zeolite Chemistry and Catalysis, J.A. Rabo Ed.; ACS Monograph 171, 1976, p585. 24. Mori K.; Miyamoto; Murakami Y. J. Phys. Chem. 1984, 88, 2741. 25. European Patent Application 0028516. 26. Parker L.M.; Bibby D.M.; Meinhold R.H. Zeolites, 1985, 5, 384. 27. Centi G.C.; Tvaruzkova Z.; Trifiro F.;JiruP.; Kubelkova L.Appl.Catal.,1984, 13, 69.



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28. MacKenzie KJ.D.; Brown I.W.M.; Ranchod P.; Meinhold R.H.;J.Materials Science, 1991, 26, 769. 29. Figaro Engineering INC., 1-5-3 Senbanishi Inc, Mino, Oska 562, Japan. 30. Patterson J.E., Programs for the Dycor Portable Mass Spectrometer, DS Chemistry Internal Report: Petone, New Zealand, 1991.


RECEIVED September 30, 1993

Catalysts for Low-Temperature Oxidation of Ethene - American

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