As a generalization, the catalytic action of active charcoal is concluded to be based O n the holding of hydrogen chloride formed through Reaction 1 near the palladium, the stabilizati011 of t,he reduced palladium compound to prevent aggregation, and the rapid reoxidation of the reduced palladium compound by the activation of oxygen. Literature Cited
Bjerrum, J., MeReynold, J. P., “Inorganic Synthesis,” Vol 2, p 216, 3IcGraw-Hill, Xew York, KY, 1946. Dozono, T., Shiba, T., Bull. Jap. Petrol. Inst., 5 , 8 (1963). Fujimoto, K., Kunugi, T., Kogyo Kagaku Zasshi, 72, 1760 (1969).
Olefin Oxidation-Mercuric Charcoal Catalysis
Fujimoto, K., Negami, Y., Kunugi, T., ibid., 73, 1822 (1970). J . Amer. Chem. Sac., 86, 3246 (1964). Henry, P. M., ~ iR., ~sedlrneier, ~ , J , , srnidt, J., Chem,, 693, 99 (1966). Larsen, E. C., Walton, J. H., J . Phys. Chem., 44,70 (1940). lloiseev, I. I., Vargaftik, 11. S., Syrkin, Ya. K., Dokl. Akad. A-auk, USSR,130, 820 (1960a). 1\loiseev, 1, I,, vargaftik, 11,x., syrkin, ya,K,, ibid,,133, 377 (1960b). Posner, A. AI.,Trans. Faraday Soc., 49, 389 (1953). Smidt, J., Hafner, W., Jira, R., Sedlmeier, J., Sieber, R., Ruttinger, R., Kojer, H., Angew. Chem., 71, 176 (1959). Yasui, A , , Kogyo Kagaku Zasshi, 72, 528 (1969). Tamura, M,, RECEIVED for review November 15, 1971 ACCEPTEDSlay 22, 1972
Salt-Active
Hiromichi Arai, Katsuya Uehara, Shin-ichi Kinoshita, and Taiseki Kunugil Department of Synthetic Chemistry, Faculty of Engineering, Cniuersity of Tokyo, Hongo, Bunkyo-ku, Tokyo, J a p a n
Catalytic reaction of isobutene with mercuric chloride supported on active charcoal in the vapor phase yielded metacrolein as a major product. The kinetics of the oxidation were determined in a fixed-bed reactor. The rate of metacrolein formation was R = k [ 0 2 ][iso-CaHs], where the value of k was 0.1 48 mol/hr,atm2, g-cat (at 140°C, Hg: 5 wt %). Reaction rates of other olefins were measured. Propylene, 1 -butene, and 2butene underwent an analogous reaction more slowly.
O r g a n i c compounds have been subjected to a number of reactions with mercuric salt’s. The addition, substitution, and oxidation reactions in the liquid phase have been reported (Kitching, 1968). The addition of oxy salts of mercury to olefins to give p-oxy organomereuric compounds is wellknown (Hoffmann and Sand, 1900). The so-called hydroxymercuration reaction is expressed as Hgz+
+ CH2=CHR + H20
+
[HgCHzCHROH]+
+ H+
where R is H, alkyl, or allyl. Stoichiometric, stereochemical, and kinetic studies in the aqueous or organic solvents for the formation of the u-mercury complex have been made extensively (Kitching, 1968; Chatt, 1951; Halpern and Tinker, 1967). Further reaction of the u-complex x i t h mercuric ion gave oxidized olefinic compounds as major products. For example, propylene gave acrolein (Fielding and Roberts, 1966). CH3CH(OH)CH*Hg+
+ 3Hgz+
+
CH,=CHCHO
+ 3H+
Although the stoichiometric reactions of mercuric ions with olefins in the liquid phase are known, no study has been reported on the catalytic reoxidation process b y use of mercurous ion or mercury. In this paper the catalytic oxidation of olefins with mercuric salts supported 011 active charcoal catalysts in the vapor phase, by use of a fixed-bed reactor, is reported. To whom correspondence should be addressed.
308
Ind. Eng. Chem. Prod. Res. Develop., Vol. 1 1 , No. 3, 1972
Ethylene is catalytically oxidized by molecular oxygen and water to give acetaldehyde over palladium salt-active charcoal catalysts without the use of redox substances such as cupric chloride (Fujimoto et al., 1972). Mercuric salts supported on active charcoal also had the catalytic activity to oxidize propylene or isobutene to acrolein or metacrolein, respectively, a t the reaction temperature of 140-200°C. Bismuth molybdate is an excellent catalyst for the oxidation of propylene and isobutene a t higher temperatures, Le., 460°C (Adams, 1965). Experimental
Materials. Ethylene, propylene, 1-butene, cis-2-butene, trans-2-butene, and isobutene were 99.9% pure. Preparation of Catalysts. Active charcoal (made from coconut; surface area, 952 m2/g, 10-20 mesh) was boiled with 10% aqueous nitric acid for 3 hr and washed with boiling water repeatedly until the final p H of rinsed water became 4. Mercuric chloride-active charcoal catalyst was prepared by dipping active charcoal in the prescribed solution of mercuric chloride in 0.LV aqueous hydrogen chloride. After adsorption the catalyst was water-washed to a p H of 4 and dried over calcium chloride. The mercuric chloride supported on active charcoal is usually 5 wt yo as metallic mercury. Prior to use, the catalyst was evacuated a t 150°C for 4 hr. Other mercuric salt-active charcoal catalysts were prepared in the same way with the acid solution corresponding to the anion of each salt. Apparatus. T h e reactor IS made from a glass tube 20 m m in diameter with a concentric thermowell. F i r e grams of
Table 1. Oxidation Products of lsobutene over Active Charcoal Without Mercuric Salts and Effect of pretreatment. Rate of formation, 1 0-6mol/hr.g-cat Pretreatment
Metacrolein
terf-Butanol
Acetone
Acrolein
Acetaldehyde
Carbon dioxide
Washed with water 1.3 4.0 0.6 0.0 0.1 2.4 0.7 1.5 0.6 0.0 0.0 3.9 Boiled wit,h nitric acid Adsorbed hydrogen chl.oride after nitric acid treatment, 0.4 14.0 0.7 0.2 0.0 1.6 OTotal pressure, 1 atm; mole ratio, isobutene:oxygen:water = 1.0: 1.0: 10.0; TV/F, 18-19 g-cat.hr/mol; temperature, 140°C. ~
~~~~~
~~~~~~
~
~
Talble II. Reactivity of Olefins over Mercuric Chloride-Active Charcoal Catalyst. Product distribution, Conversion,
%
Olefin
Unsaturated ketone or aldehyde
Saturated ketone
Croton aldehyde
Acetaldehyde
%b Saturated alcohol
Unsaturated alcohol
Carbon dioxide
0.0 0.0 100.0 0.0 0.0 0.0 0,049 0.0 Ethylene Propylene 0.62 61,2c 2.5d 0.0 2.7 13.48 0.0 20.4 0.0 16.cih 4.3 0.8O 5.9 0.3 67.5' 1-Butene 2.27 4.4 4.9 25,6i 8.2h 7.7 4.Y0 0.68 41. 3' cis-2-Butene t rans-2-Butene 0.48 37.9' 4.00 10.3 4.8 19. j i 4.8h 14.5 0.0 0.1 7.Y'i 0.0 2.5 4.9d 80.3f Isobutene 20.9 a Temperature, 14OoC!;o1efin:oxygen:water = 1.0: 1.0: 10.0; total pressure, 1 atm; W l F = 18-19 g-cat.hr/mol. "Based on olefin fed. 'Acrolein. dAcetone. eIsopropanol. /Methyl vinyl ketone. Qllethylethyl ketone. hhIethyl vinyl carbinol. "ec-Butanol. jhletacrolein. ktertButanol.
catalyst' was charged t o a bed length of 10 em. Catalyst particle size was 10-20 mizsh. The glass particles of about' 2 mm in diameter were charged above the catalyst bed to preheat the mixture of reactants. Procedure. A11 t.lie experiments were made under atmospheric pressure. Each component gas was measured separately and mixed wit,h the others prior to feeding into the reactor. JV/F !vat; between 10 and 20, where W is the catalyst weight (grams), and F is t'he total gas flow rat'e (mol/ hr). The exit' gas from the react'or was cooled in a water colidenser, through which continuous sampling of the products could be made for gas chromatography. Sampling of the product gas was always made under steady-state conditions. Alcohols, aldehydes, and ketones were analyzed by gas chromatography with a polyethylene glycol 400 column a t 60°C.
IO0
Results and Discussion
Effect of
180
Temperature ("C)
Catalyst Preparation o n Reactivity. T h e
behavior of isobutene oxidat,ion over active charcoal is highly dependent upon pretreatment of the active charcoal. As shown in Table I, the treatment' of charcoal with 0.5N nitric acid for 3 hr a t 100°C produces much carbon dioxide. I n several pretreatments of active clnarcoal, boiling with diluted iiit'ric acid gives the best, result' in the oxidation of olefins by mercuric salt-active charcoal catalysts. The rate of metacrolein formation increases linearly n-ith the supported amount of mercuric chloride on active charcoal up to 5.0 wt yo and has a maximum between 5-10 n t yo.h larger amount of mercuric salt reduces the activity for metacrolein, and in such a case: small particles of metallic mercury were often found on the catalyst surface after reaction. Effect of Temperature. T h e osidat,ioii of isobut,ene gives metacrolein as a main product, and in addition, tert-butanol, acrolein, acetone, carbon dioxide, and a trace of acetaldehyde are produced. The relat'ionship between the rates of formation of these products and the reaction temperature is shown in Figure 1. The rate of metacrolein formation increases up to 150°C and then decreases, whereas that of carbon dioxide
I40
Figure 1. Oxidation of isobutene with mercuric chloride. Effect of temperature. W / F , 1 1-1 2 g-cat.hr/mol; total pressure, 1 atm; mole ratio, isobutene :oxygen :water = 1 .O : 1 .O: 10.0; HgC12, 9.53 wt yo as mercury melal; V , rate of formation of each product
0 Metocrolein
terf-Butanol 0 Carbon dioxide
0Acrolein A Acetone
increases rapidly above 160OC. *it the lower temperature where the formation of carbon dioxide is substantially negligible, the activation energy for t,he metacrolein formation was 7 . 3 kcal/mol. Tert-butanol seems to be formed by the hydration of isobutene on the acid sites, and it increases over the active charcoal which was treated wit'h hydrogen chloride. Reactivity of Olefins. Oxidation products from various olefins are shon-11 in Table 11. Ethylene produces only carbon dioxide. As a main product, 1-butene gives methyl vinyl ketone, and isobutene gives metacrolein. The conversion of olefins under the same experimental conditions is in the order: isobutene > 1-butene > cis-2Ind. Eng. Chem. Prod. Res. Develop., Vol. 1 1 , No. 3, 1972
309
Table 111. Oxidation Temp, OC
Salt
of lsobutene over Various Mercuric Salts-Active Charcoal Catalysts. Product distribution, % Conversion,
%
Metocrolein
HgClz 140 28.3 77.7 Hg(CH3COOj z 98 10.3 79.1 72.2 Hg(CF3COOj2 100 13.7 140 9.4 68.4 HgBrz 140 5.6 63.0 HgI2 HgSOd 140 5.5 16.4 aTotal pressure, 1 atm; mole ratio of isobutene:oxygen:water are 5.0 wt % as metallic mercury.
1001
tert-Butanol
Acetone
Acrolein
Carbondioxide
Acetaldehyde
6.0 6.3 18.7 24.6 22.0 15.8
=
7.5 3.3 0.5 3.3 0.0 0.5 3.2 0.0 0.1 3 6 0.0 0.1 7.3 0.0 1.1 43.2 0.0 0.3 1.0: 1.0: 10.0; W / F , 18-20 g-cat.hr/mol; mercuric salts
5.0 10.9 5.7 3.3 6.6 24.4 supported
f00
I
t
0 0 I
a
L:
E
-
\
0
E t
-0x
2
4
8
10 12 Stream hours( hr) 6
14
Y
16 '0 t7i
Figure 2.
Conversion and selectivity vs. hours on stream. W/F, 19.0 g-cat.hr/mol; total pressure, 1 atm; mole ratio, isobutene :oxygen :water = 1 .O : 9.4 : 52.0; HgCI2, 5.07 wt % as mercury metal; temperature, 140°C
>
0 -a
-0 I
I -0.1 0.0I
log pU+(
0 Conversion 0 Metocrolein A C a r b o n dioxide
butene > propylene > trans-2-butene > ethylene. These results agree with the order of rate constants for olefin oxidation in mercuric trifluoro acetate solution (Fielding and Roberts, 1966), and this suggests that our gas-phase reaction proceeds in the same way as in the liquid-phase reaction. Reaction with Other Mercuric Salts. T h e effect of anioiis of mercuric salts on the rate of oxidation of isobutene was studied, and the results are listed in Table 111. It is difficult to compare the effect under the same reaction temperature because of the different stability of the supported mercuric salts. Mercuric acetate gives almost the same selectivity of metacrolein as mercuric chloride, whereas mercuric iodide produces more tert-butanol, and mercuric bromide and sulfate produce more acetone. Rate Expressions and Reaction Scheme. About 18 moles of metacrolein per 1 mole of mercuric chloride was formed in 16 hr, and the catalytic activity became nearly constant after 10 hr, as shown in Figure 2. Therefore, this oxidation reaction is a catalytic reaction, undoubtedly. I n Figures 3-5, the reaction rates were measured a t 140°C over mercuric chloride catalysts (HgCl?: 5 w t yoas metallic mercury) with varying partial pressures of oxygen, isobutene, and water, with nitrogen as the diluent. The reactions were first order with respect to oxygen and isobutene. The rate expression is d [metacrolein] dt
=
k , [02) [isobutene]
where k , = 0.148 mol/hr.atm2.g-cat. The reaction kinetics of the formation of carbon dioxide and tert-butanol obey the following forms: 3 10
Ind. Eng. Chem. Prod. Res. Develop., Vol. 1 1, No. 3, 1972
at m 1
0.I
Figure 3. Effect of partial pressure of isobutene. W/F, 18.0 g-cat.hr/mol; total pressure, 1 atm; mole ratio, isobutene nitrogen :oxygen :water = 1 .O : 1 .O : 10.0; HgCI2, 5.0 wt yo as mercury metal; temperature, 140°C; V, rate of formation of each product
+
0 Metacrolein
fert-Butanol 0 Carbon dioxide
d [tert-butanol] dt = kh[isobutene] [H20]
where rate constants a t 14OOC are k,
=
kh =
0.0022 mol/hr.atm.g-cat 0.0010 mol/hr.atm2.g-cat
Xercuric chloride seems to be reduced to mercurous chloride and metallic mercury during the reaction. However, metallic mercury easily reacts with mercuric chloride to give mercurous chloride (Hassler, 1963). Therefore, mercurous chloride is suggested substantially as the main reduction product on the catalyst, and it is necessary to oxidize mercurous chloride to mercuric chloride for the catalytic reaction. It is reasonable to assume the catalytic reoxidation of mercurous chloride by active charcoal, since the air oxidation of Fe2+, Sa2+,Co2+, and P d is known (Larsen and Walton, 1940; Bjerrum and McReynolds, 1946; Posner, 1953; Fujimoto et al., 1972). Young and Kood (1946) reported that mercuric and mercurous chloride were formed by treating active charcoal saturated with mercury vapor, with hydrogen chloride and
t
I -
n t
I::
0
7 10-
m
t
-
t
--
X
x
Y
t
Y
>
>
'9
a
-
0
L
-
b, 0
(atm)
+
H tert-Butanol
0
'
10.1 I
tog PhD (atm)
0.1
0.I
Figure 4. Effect of partial pressure of oxygen. W/F, 18.0 g-cat.hr/mol; total pressure, 1 atm; mole ratio, isonitrogen :water = 1 .O : 1 .O : 10.0; butene :oxygen HgCI?, 5.0 wt % as mercury metal; temperature, 140°C; V, rate of formation of each product
0 Metacrolein
a
0.I
I 0.01
log Poz
' I
Figure 5. Effect of partial pressure of water. g-cat.hr/mol; total pressure, 1 atm; mole ratio, nitrogen = 1 .O : 1 .O : 10.0; oxygen :water wt % as mercury metal; temperature, 140°C; formation of each product
+
0 Metacrolein
H terf-Butanol
W/F, 18.0 isobutene: HgC12, 5.0 V, rate of
0 Carbon dioxide
Carbon dioxide
methyl vinyl ketone seems to be produced via the intermediate (111)from 1-butene and 2-butene. oxygen. Therefore, the route for mercuric chloride from metallic mercury is also powble in the catalytic reaction. The kinetics of the hydrouymercuration of olefins was studied in aqueous perchloric acid solution (Halpern and Tinker, 1967). The rate eupression for the o-mercury complel was rate = k[Hgz+] Iolefin]. The formation of acrolein from the a-mercury complex is first order with respect to 2-hydrouy prop! 1 mercuric trifluoro acetate and mercuric ion (Fielding and Roberts, 1966). These results suggest that the a-mercury complex reacts with mercuric ion to produce acrolein. Oxidation of propylene by mercuric acetate gives nmr spectra 1%ith the AX, proton pattern for rapidly equilibrating a-allyl species (I) and (11) (Rapport et al., 1965).
H
H
I
H
H
H I
H
CH,
/
'\
HgX (1)
\
/
H
HgX (11)
Strini and 1Ietzger 1966) reported that CH3-CH=13CH2 reacted with mercuric ion in perchlorlc acid solution to produce equal amounts of both 13CH2=CHCH0 and CH2= CH13CH0and that both terminal carbon atoms in propylene submitted to the acrolein formation by mercuric ion prove the symmetrical nature of the intermediate after dehydration of the a-mercury complex occurs. As shown in T a b k 11. a e obtained mainly acrolein from propylene, metacrolein from isobutene, and methyl vinyl ketone from 1-butene and 2-butene over mercuric chlorideactive charcoal catall st in the presence of steam. Based on the above discussion about acrolein formation from propylene,
H
\
/
H
HgC1
seen in Table 111, over mercuric chloride, acetate, and trifluoro acetate catalysts, metacrolein is the main product, whereas fert-butanol and metacrolein are the main products over mercuric iodide catalyst. The bond strength of the carbon-mercury bond in methyl mercury compounds (CH3HgX) is in the following order (Scheffold, 1969) :
CF3COO-
H
H 'I
> C1- > CH3COO- > Br- > I-
When the carbon-mercury bond is weak, the o-complex is decomposed a t the carbon-mercury bond to produce the carbanion, which reacts with protonic acid to give terf-butanol.
OH HgX
OH HgX
When the carbon-mercury bond is strong, the u-complex is dehydrated to produce the o-allyl comples, which reacts with mercuric salt, water, and os\ geii to give metacrolein. Ind. Eng. Chem. Prod. Res. Develop., Vol. 1 1 , No. 3, 1972
31 1
literature Cited
CHO-C=CH,
+H20
HgXz
+ HgZXz
+ 2HX +
‘/202
+2HgXz
+ HzO
The oxidation of propylene and the four butenes over bismuth molybdate is first order in olefin and independent of oxygen and products a t 450-55OOC (Voge and Adams, 1967). An allylic species is most probably the first catalytic-adsorbed intermediate by isotopic labeling carbon atoms, and it demonstrates that the second step of the attack may occur a t both ends of this species. The oxidation by mercuric ion catalyst proceeds a t a lower temperature than that by bismuth molybdate catalyst. This catalysis system suggests that many chemical reactions in solution can be applied to the heterogeneous catalytic reaction. Acknowledgment
The authors are indebted to Yasukazu Saito for his helpful discussions.
Adams, C. R., Proc. 3rd Int. Congr. Catal., Amsterdam, 1964, Vol 1, p 240, North-Holland, Amsterdam, Xetherlands, 1963. Bjerrum, J., JIcReynolds, J. P., Inorganic Synthesis,” Vo1 2, p 216, McGraw-Hill, S e w York, NY, 1946. Chatt, J., Chem. Rev., 48,7 (1951). Fielding, B. C., Roberts, H. L., J . Chem. SOC.,1966, p 1627. Fujimoto, K., Negami, Y., Takahashi, T., Kunugi, T., I n d . Eng. Chem. Prod. Res. Develop., 11 (3), 303 (1972). Halpern, J., Tinky, H. B., J . Amer. Chem. SOC.,89, 6427 (1967). Hassler, J. W., Activated Carbon,” p 286, Chemical Publ., New York, XY, 1963. Hoffmann, K., Sand, J., Chem. Ber., 33, 1340,2692 (1900). Kitching, W., Organometal. Chem. Rev., 3,61, 134 (1968). Larsen, E. C., Kalton, J. H., J . Phys. Chem., 44, 70 (1940). Posner, A. AI., Trans. Faraday Soc., 49, 389 (1933). Rapport, Z., Sleezer, P. D., Winstein, S., Young, W. G., Tetrahedron Lett., 42, 3719 (1965). SchelTold, R., Helv. Chzm. Acta, 52, fase 1, 56 (1969). Strini, J. C., Metzger, J., Bull. @c. Chim. Fr., 1966, pp 3145, 3150. Voge, H. H., Adams, C. It., Advances in Catalysis,” Vol 17, p 151, Academic Press, New York, NY, London, England, 1967. Young, K. R., Wood, W.C., BIOS Final Report So. 104 through Chem. Trade J., September 6, 1946. RECEIVED for review December 13, 1971 ACCEPTEDMay 22, 1972 Hiromichi Arai acknowledges the aid of the Bakkokai Research Foundation.
Plasticizing Effect of Methane Permeation in Polyolefinic Films Edward S. Matuleviciusl and Norman N. Li Corporate Research Laboratories, Esso Research and Engineering Co., Linden, N J 07036
A method is described which combines a maihematical solution of the diffusion equation wiih a pressure desorption experiment that permits rapid evaluation of the solubility, diffusion coefficient, and the extent of plasticization. The diffusion coefficient is calculated by use of this technique for methane in polyethylene and polypropylene. Also, certain precauiions must be used to prevent gas-phase mass transfer from influencing the results.
T h e permeability of vapors and gases at high pressure shows a complicated dependence on pressure by virtue of strong interaction between solute and membrane. Exponential equations can be used to relate the permeability to the vapor activity (Friedlander and Rickles, 1965). Similarly, a similar plasticizing effect occurred with hydrocarbon gases a t high pressures (Li and Long, 1971). For many studies Li and Long found that permeability could be expressed as
c =
(1)
Also, methane iya-meability in imlyethylene and l)olyl)ro13ylene obeyed Henry’s Law up to 55 a t m (Li, 1969) :
To whom correspondence should be addressed. 312
Ind. Eng. Chem. Prod. Res. Develop:, Vol. 11, No. 3, 1972
(2)
Since permeability is the product of the solubility and i.e.~ diffusion
F’
=
DH
(3)
the diffusion coefficient can be expressed as
D = Po’eAP
HP
=
Doeac
(4)
I n this study a method was developed which combines a mathematical solutioii of the diffusion equation with simple experiments to determine the diffusion coefficient and plasticizing effect, a, a t high pressure for methane in polyolefinic films. This technique permits rapid determination of the solubility and diffusion coefficient with a simple test.
