CA1076321A - Process for manufacturing chlorine dioxide - Google Patents

Abstract

PROCESS FOR MANUFACTURING CHLORINE DIOXIDE
Abstract of the Disclosure:
Chlorine dioxide is generated very efficiently and safely by reducing a chlorate in a strong acid in the presence of a complex catalyst consisting of palladium (II) and a .beta.-diketone derivative.

Description

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1. Fi~ld o:E the In~ention This invention relat~ a process for maml~acturing chlorine dioxide by r~duci~ a ohlorate ln a ~t~ong acid S in t~e presence o~ a cataly~t,.
20 De~cription of Prior Art Chlorine dioxide i 8 a commercially ~mporta~t ma~erl~l ~n 8uch fields as pulp bleachlng, wat~r tr~at~en~ ~nd fat d~coloring, and also ha~ recen~ly been u~ed in the fields of dQnitration of industrial waste gases and removal o~ !
phenols from tndustrial ~wage. Thus tt i~ highly desira-ble to have a process by which chlorine dloxide can be manufactured econo~ically~ Further it ls deslrable to hav~ a safe process in which the gen~ration o~ chlorine dioxide can be ea~ily co~trolled withou~ any danger o~
explosion~
One o~ the methods for ge~eratiDg chlori~e dloxide i~ to reduce a chlorate wlth a reducing agent in a strong acid. Th~ r~act~ons which occur are ex~mpli~ied b~low~
wherein, for th~ sake o~ illustration9 ~he chloratQ u~ed i8 sodium chlorate and the reduc~ng agen~ is hydroohloric acid.
NaC103 + ZHCl >C102 + 1/2C12 ~ NaCl ~ H20 (1) NaC103 ~ ~HCl >3C12 ~ NaCl ~ 3H20 (2) Chlorine dioxide is formed by reaction ~1), but not ~ormed by reaction (23 ~hich competes with reaction (1).
Accordi~gly~ reactlon (1) mu~t be accelerated in order to generate chlorine dioxide e~icientlyO A u~e~ul method to achieve this puxpo~e i~ to u~e a oatalyst whlch accelerates reaction (1) in pre~erence to reaction (2~

~.b 107~3'h~

Palladium was described in Japanese Paten~ Publica~
tion No. 2,645/1970 as a catalyst ~or chlorine dioxide production. Vanadium pentoxide, ~ilver ion, mang~nese ion, dichromate ion ~nd arsenic ion were de~cribed ln U,S~ Pat., ~9563,702 for ~he same u~age. Further, ~or the same purpose Ja~anese Patent Publication No~. 4~119/~9609 7,301/1962, 14,958/1964, 17,047/1966 disclose manganese compounds; silver ion or a combi~ation of ~ilver ion and manganese ion; manganese (II) chelate compounds alone or combination o~ mangane~e chelate compounds and metal ~equester~ng agents; lead lon or a co~bination o~ lead ~on, msnganese ion and ~ilver ion; respectively~ It is well known in the ~ield o~ thi~ invention that the ratlo o~ the rate of reaction (1) to ~hat o~ reaction (2) decreases at lower value~ o~ the chlorate-~o-reduclng agen~ molar ratio and at lower acid concentratio~s of the reaction medium, although the generatlon of chlorine dioxide ~ der suoh co~dition~ oan be con~rolled ~ore ~a~ily, How~ver, tho~e catalyst~ do not have satlsfactory actlviti~
under the co~d~tions d~scrlbed above. E~en with palladium which shows the highest activity among them, the ratio o~
~he rate o~ reaction (1) to that of reaction (2) ~ound under th8 ~ollowing condition~ ~carcely exc~ed~ a value of 17: an acid conc~ntration of 0~4 moles per liter o~
th~ reaction medium, a chlorate-to-reducing age~t molar ratio o~ 0.27 and a pall~dium (II) concentration of O~OQl mole per liter of the reaction mediu~.
Recentlyg a proces~ ~or manu~acturi~g chlorine dioxide at lower acld concentr~tlon~ ~nd at r~mark bly high co~centrations of a reduc~ng agent ~e~g., Brltlsh 3 ~

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Pat. 1, 347, 740~ has been developed. Under such reactlon <~onditions even ~s)re active catalysts ar~ r~quired in ord0r to K~n~rata ~hlori~ d$oxid~ withou~ lo~s OI
efficiency.
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It i~ an ob,~ect of th~ s invention, thereforeg tn provide an exc~llent catalyst ~r efficiently mallu~actur-ing chlorine dio~c~d~9 ~ald catalys~ h~ing a high catalytic activity ev~ d~r th~ e~ily s~on~rollabl~ eonditions o~
10 low ac~d concentra~ion~; and low chlorate-to-r~duci~ a~ent molar ratios of the reaction medium.
It ls another ob~ect of th~s inYention to provide a process for e~icien~1y ~nanu~ctur~g chlorine dio~cida by u lng an exc~11ent cataly~t which ha~ a high catalytic 15 acti~rity e~en und~r ~ ~a~i1y con~rollabl~ G~nditio~
of low acid concen~raltio~ and low chlorat~to-r~ducing agent mo1ar ratios of` th8 re~ctio~ ~edium.
Other ob~ect~ and advanta~e~ o~ the pre~e~ vell-tion may become apparent to tho~e skilled irl the ark ~rom 20 the following de~cription ~d di~closure.

Figure 1 ~how~ the relatio~ e~?erimental1y found between the ratio of a NaC103 consuD~ption rate in the reaction (1) to another rate i~ the react10n (2) and the 25 ooncen~ration of ca~lysts iXl the reaction medium.
Figures 2 through 5 show the infrared spe¢tra correspond~ng to the ~ollowing ~ystems: palladll~ (II) -

2~4-pentanedione comp1ex, 294-pen~nedione, ph1ladium (II) -1-phenyl~ butanedlone complex and 1-pheny1-1,3-butane-~0 dione, respectively.

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This in~ention relates to a proces~ for manufactur-~n~ chlorine dioxide by reducing a chlorate in a ~trong acid in the pr~sence of a complex catalyst ~on~isting of 5 palladium (II) and a ,3~diketone d~rivatlve ha~ g a general formula Rl 11 7 ~ R2 wherein Rl and R2 are selected ~ro~ the gr~up consisting of hydrogen~ an alkyl radical having from 1 to 10 carbon atoms, and an aryl radical; arld R5 aIld R4 are s~lected from the group consi3ting of hydrogen of a methyl rad~cal.
The strong acld used in the process of this in~en-tion is selected from the group consi~ting of sul~uric acid, hydrochloric acid and a mixture thereof. me con-centration of the sul~uric acid may be ~rom 0.5 to 6 moles per liter o~ the raaction medium. The concentration o~
the hydrochloric acld may be ~rom 0.01 to 4 moles per liter of the reaction medium. But if the concentration of sul~uric acid is below 095 or that of hydrochloric acid below 0.01 mole per liter, the rate o~ chlori~e dioxlde generatio~ becomes too slow. On the other handg if the concentration o~ ~ulfuric acid exceeds 6 or that o~ hydrochloric acid 4 moles per liter9 the rate o~ reac-tion becomes too ~a~t to as~ure ~a~ety.
Said chlorate is generally ~elected ~rom the group consisting o~ sodium chlorate, potass~um chlorate9 calcium chlorate and magnesium chlorateg The concentrat~on of the chlorate may be .~rom 0.01 to 5 moles per liter o~ the 107G32:1 reaction medium. If ~t is below 0.01 mole per liter9 the rate o~ chlorine dioxide generation becomes too slow. On ~he other hand9 i~ it exceed~ 5 mole~ per liter o~ the reaction medium, it becomes too fast to a~sure sa~ety in op~ration and the 10~3 0~ the expensive chlorate increa~es.
A~ said reducing agent~ ~ulfur dioxide, methanol, sodium chloride9 calcium chloride, pota~sium chlor~de or hydrochloric acid is co~monly u~ed~
Said complex cat lyst consisting of palladium (II) and a ~-diketone derivative i~ read$1y prepared by di~olv-ing a palladium (II) salt and a ~-diketone der~vativa i~to water. It can be obtained in a crystalline ~orm by neutral~
izing an aqueou~ solution containing palladium (II) and a ~-diketone derivative with an alkal~e ~olution and by filterin~.
Said ~-dik~ton~ derivative i~cludes 2~4-p~ntanedione;
2~4-hexanedione; 2,4-heptanedione; 5 methyl-2p4-hexanedione;
2-ethyl-2,4-pen~an~dione; 2~4~octanedione; 3,5-octa~edi~ne;
5-methyl-2,4-heptanedione; 3-methyl-2,4-heptanedione; 4-methyl-3,5-hepta~edion~; 5,5-d~methyl ~;~29 4~hexanedlone 9 2,4nonanedione; 496-no~a~edione; 6-methyl-2,4-oct~nedione;

3-m~hyl-2,4-octanedio~e; 2-~ethyl-3,5-octa~ed~ona; 4-meth~l-3,5-octan~dione; 5-ethyl-2,4-h~ptanedlo~e; 6t6-dimethyl-2,4-hepta~edione; 2~2-dimethyl 3,5-h~pta~d~one;
2,4-dlmethyl-3,5 heptan0diQna; 2,4-d~canedio~; 3,5-decan~dio~; 2 ~thyl-3D5~no~an~i4ne; 5~ethyl~4~6 no~anedion~; 8~ethyl~406-non~nedion~; 797-d~ethyl-2v4D
octa~dio~e; 2,7-dl~thyl-3~5-oct~nedione; 3~i50propyl-29 4-heptanedlone; 2~2,b_trim~thyl-~5-heptanedione; 3-butyl-2,4~hexanedione~ 2,4~undecanedlone; 4,6~und~canedion~;

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5,7-undecanedione; 2,~-dode~ ione; 597-dodecanedione9 2~4~tridecanedione~ 6,8 tridecanedione; 2j4~tetradec~ne~
dione; ~,8-~etradecanedione; 1-phenyl-1,3~buta~edione;
l-phenyl-1,3-pentanedione; 1-phenyl-2,4-hexdnedione; 1-phenyl-1,3-hexanedione; 1-phen~1-3,5-hexanedione; l-phe~yl-

4-methyl-1,3-pe~ta~edlo~e; l~ph~ 1,3-heptan~dlo~
phenyl-4~ethyl-1,3-hexan~dione; 1-phenyl-2,4-nonanedio~e~
1,3-diphenyl-1,3-propaned~o~e; 1-fluoro-2,4-p~n~anedione;
l-chloro-2,4-pentanedione; 1,5-difluoro-2~4-pentanedione;
1,1-difluoro-1-chloro-2,4-pentanedio~e; 13 19 l-tri~luoro-2,4-p~ntan~dione; 19191~5,5,5-hexa~luoro 2~4~pe~anediane 1,1-difluoro-1-chloro-2,4-hexanedione and the like.
The concentration of said complex cataly~t may be from O~OOOOl to O.l mole per liter o~ the reactlon mcdiumO
I~ it ls below O.OOOOl mol~ per liter9 the rate of chlor~ne dloxide generation is not accelerated by a measurable amount. On the other hand, when it is abov~ O.l mole per liter of the re~ction medium, there i~ no particular advantage and the production cost b~¢om~s higherO
The preferred concsIltratioll OI said complex cataly~t is from O~OOOO~ to 0.005 mole~ per liter o~ the reactio~
medium~ The complex cataly~t cons~tlng o~ palladium (II~
and a ~-diketone derivat~re of the pre~ent in~ention ac-celerates the rate of reactio~ (1)~ but does not accelerate that o~ reaction (2). Accordi~gly, the catalyst lncreases the convers~on from the chlorate to chlorine dioxlde re~
markably. The ratio of reaction (1) rat~ to reactlon (2) rate in hydrochloric acld was ~ound to b~ les~ than 30 with any one of the conventional cataly~ts ~entioned above~
whereas a value of as high a5 78 was obtained with a complex ~7~32~L

c~talyst of this inYention.
Advantages obtained with the present i~ention are as follows: The rate of reaction (1) is remarkably ac-celera~ed by adding a complex oatalyst consl~ting o~ pal-ladium (II) and a ~diketone derivatlve to the reaction medium even at low acid concentrations or low chlorate-to-reducing age~t molar ratio. Accordingly, the volume of the reaction vessel requlred for generating chlori~e dioxide at a given rate can be reduced remarkably from those most frequently used in the prior art. The concen-trations of the chlorate and the strong ~cid in ~he reac-tion medium can be reduced by adding thereto a complex ca~alyst consisting o~ palladium (II) and a ~-diketonQ
derivative. As a result, the generation of chlorine dioxide is co~trolled more easily and becomes more e~
ficien~. Further more, abnormal generation or explosion of chlorine dioxide can be avoidedg since lower reaction temperatures can be u~edO While the complex catalyst consisting of palladium ~II) and a ~-dlketone derlYative alone has a remarkable catalytic a~tivity, it can be used to~ether with conventional catalyst~ resulting in ~urther increa3ed activity. As ~uch cat~lysts, palladi~m ion, vanadium pentoxide, ~ilver lon, mang~nese ion9 dichromate io~, arsenic lon, lead ion, and thallium ion are used.
The followiDg examples are giv~n tG further illustrate thls inven~lon, but it should be u~derstood that the inve~-tion is by no means limited th~reto. On the contrary, they are given only to clari~y so~e o~ the essential work-ing modes of the pre~ent in~ention~

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One hundred and ~i~ty ml of an a~ueous solution conta~ning NaCl and ~aC103 were charged in a four-necked ~la~k and tha ~olution was k~pt at 70C. One hundred and fi~ty ml o~ another ~ueous 501ution con~a~n~ng ~Cl, NaCl and palladium (II) ~ 2~4-pentanedione complex (It i8 a yellow cry~tal. Its melting poin~ iB 180 - 181C~ Its infrared spectru~ ls shown in Figure 2.) were heated up to 70C and was added to ths ~irst solution. Thus, chlorine dioxide was generat~d. The compo~ltion of the reaction medium was 0.4 mol/l HCl, 100 g/1 NaC103, 200 g/l NaCl and 0.01 mol/l palladium (II) - 2,4-p~ntanedione complexO
The react~on medium was agitated by introducing air thereto at about 500 ml/min and then the reaction medium and the gas phase ~ere analyzed every 5 m~nutes.
The rate at which NaC103 consumed 1~ reaction (1)9 Rl was 9~17 m mol/l-min and that in reactio~ (2), R2 wa~
0.12 m mol/l~min w~ile the concentration ~f HCl decrea~ed to 0.3 mol/l, Accordi~gly, th~ ratio of Rl to R2 was 77.7, E~ s 2 - 6 The procedure de~cribed ln Exampl~ 1 wa~ repea~ed except that the concentratlon o~ palladium (II) 2~4-pentanedione complex was varied.

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Table 1 Concentrati4n o~ Rate at which NaC103 was con~umed Pd (II) 2,4- By reactlon (1) By reaction (2) R /R
complex Rl R2 (mol/l) ~m mol/l-min) (m mol/l~min) 2 0.005 ?.05 0.11 64 ~ 0.001 3.7~ 0.12 31 4 O.Q005 20 55 0012 21 OoO001 lo 09 0~ 11 9~ 9 6 0.00005 0~83 0.12 6.9 The procedure described in Example 1 wa~ repeated except that PdC12 alon~ was used as the catalyst.
The results obtained are give~ in Table 2 below.

Table 2 Co~centrat$on of Rate at which NaC10. was consumed Ref~rence PdC12 By reaction (1) By reaction (2) R /R
Example Rl R2 1 2 (mol/l)(m mol/1min) (m mol/l.min) 1 0.~1 3.91 0.13 30 2 0.001 1,91 0.11 17 3 0.0001 0.71 0.12 6 4 none 0.24 OolZ 2 The relation between the ratio o~ the rate at w~ich NaC103 was consumed by reaction (1) to that by r~action (2) and the concentration o~ palladium (II~ in the r~action medium in Examples 1 - 6 and Re~erenoe Exampleæ 1 - 4 ~763~

described hereinbefore are illustrated in Figure lc ~ample Z
The procedure described in Exa~le 1 was repeated e~cept that palladium ( II ) ~ l~phe~yl~ butanedione

5 compl~x (It i~ a brown crystal" Its melting point 1~
158 - 160C. Its infrared ~pectrum i~ shown in Figure 4c ) was used as the catalyst.
The result~ ob~ained are g~ven in Table 3 below.
T~le 3 Concen- Rate at which NaC103 wa~ consumed tr~t onBy reaction (13 By react Rl/R~

(at lyst (m mol/ltmin) (m mol/l-min) 7 Pd (II) -- 0.01 9.01 01.12 75 l-phenyl-1, 3-buta~e-d~ one E~amples 8 - 12 The procedure de~cribed ~ Example 1 was repeated except that the catalyst wa~ cha~gcd., The r~sults obtained are gi~e~ in Table 4 belo~r,.

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P~ ~ 0 CD
~ ~ ~
~ _, ~
g ~ ~i rl O
~, ~ pcu~ ,, ,, ~ ,, ~
O D ~ O O O O O

S': ~1 ~ _~
~ g ~
~1 00 ~ ~D
~ rl~ C~
D h Ei 1!- ~ CD 1 ~ r: ~
O
0 ~
~J
P~ ~1 ~I rl ~1 a) Or O
~ ~3 C~ O V O O
o q~ ta ~) O Cl tO i I
~ ,~ ... ~
,~ ~ o ~1 f~
~1 0 ~d ~ ~ ; ~ O
O I I ~ I ~ q `~
r~ 1~ ~.
X H ~ X H ~ ~ H ~ X
~1 H a) H H 11~ ~H O ~I H h 1--l H :~ ~1 ~ `-~oP~
O q~ ~ ~ O ~ ~ ^ O~ ~ O ~ ~ O
a~
~ 0 ~ o ~ ~

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One hundl~ed and ~i~ty ml o~ an aqueou~ solution containing NaC103 and NaCl were charged in a four-necked ~lask and the solution was kept at 70C. One hundred and ~ifty ml of ~nother aqueous solution con~ain~ng H2SO~ and palladium (II) - 2,4-pentanedione complex were heated up to 70C and added to ~he first ~olution~ Thu~, chlori~e dioxide was generated. The composition o~ the rea~tion medium was 2 mol/l H2S04, 100 g/l NaC103, 50 g/l Nacl and 0.001 mol/l palladium (II) - 2,4-pentanedlone complex.
The reaction medium was agitated by introducing air there into at about 1500 ml/min and th~n the reaction medium and the gas phase were analyzed ~very 5 minutes.
The rat~ at which NaC103 consumed in reaction (1~, Rl was 25.0 m mol/l-min and that ~n reaction (2~, R~ wa~
0.27 m moltl-min when the conc~tration o~ H2SO~ dQore~sed to 1.75 mol/l. Accordingly~ the ratio o~ Rl to R2 was 93.
Reference Ex~m~le ~
The proced~re described in Example 13 wa~ repeated except that palladiu~ (II) was u~ed as the cataly3t.
The rate at which NaC103 consumed in reaction ~1)9 Rl wa~ 13 m mol/loDin and that ln reaction (2), R2 wa~
0,26. Accordingly, the ratio o~ Rl to R2 was 500 Exampl~s 14 - 1~
The procedure described in Example 1 was repeated except that a combination of a complex cat~lyst and a conventional c~taly~t ~as used a~ a catalyst.
The re~ults obtained are gi~en in T~ble 5 bel~w.

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Concen~ration o~ catalysts Rate at which NaC103 was con~3umed Example Pd(II)-2,4- Con~ventlonal By r~action (1) By reaction ~2) Rl/R2 .
pe~tanedion~ c~*aly~t ~ R2 ~mPol/l) (mol/l) (m mol/1-1nin3(m Dlc~l/lolain) 14 10-3 Pd(II) 10 3 6~02 0.12 50 10-3 Mn(II) 10 3 4.62 0.11 42 16 10-3 Pb(II) 10 2 4.42 Ooll 40 17 10~3 Tl(II) 10 2 5.35 0.12 45 The procedure described in Ex~mp~es 15 - 17 was repaated except that the c~n~entional ~atalyst alon~ wa~
u~ed a~ a oatalyst~
The result~ obta~ned are given in Table 6 below, Table 6 ~`
Rat~ at which ~aC10~ was con~umed Conc~ntration ce conventional ~Y reac~Q~ (1) By reactio~ (2~ Rl~R2 Example catalysts Rl R2 (mol/l) (m mol/l-min) ~m mol/l.m~n)

6 Mn 10-3 1~00 0~11 9

7 Pb 10 2 0.55 0.10 6

8 Tl 10 2 0.22 0.10 2 ~ea~
m e procedure described in Example 13 wa~ r~peated except that palladium(II)--2~pent~nedio~e a~d silv~r (II) ~ 7 ~ 3~
ion were used as a catalyst.
The ooncentrations of palladium(II)~2,4 pentaIledione and silver (I) in the reactio~ m~dium were 10 3 and 10 4 mol/l, respectively. The rate at whlch NaC103 consumed in reaction (1)~ Rl was 32~5 m mol/l-mi~ and that ~n reac-tion (2), R2 was 0.25~ Accordingly, the ratio of Rl to R?
was 128.
Ref rence Example ~
The procedure descri~ed i~ Example 18 was repeated except that silver ~I) wa~ used as a catalyst.
The concentration of silv~r (I) i~ the reactlon mediu~ was 10 4 mol/l. The rate at which NaC103 co~sumed in reaction (1), Rl was 7.98 m mol/lomin and that i~ reac-tion (2), R2 was 0.25. Accordi~gly, the ratio of Rl to R2 was 32.

Claims (17)

The embodiments of the invention in which an exclusive property or privilege are claimed axe defined as follows:

1. A process for manufacturing chlorine dioxide by reducing a chlorate selected from the group consisting of sodium chlorate, potassium chlorate, calcium chlorate and magnesium chlorate, in a strong acid selected from the group consisting of sulfuric acid present in a concentration of from about 0.5 to about 6 moles per liter of reaction medium, hydrochloric acid in a concentration of from about 0.01 to about 4 moles per liter of reaction medium and a mixture thereof, in the presence of a complex catalyst consisting of palladium (II) and a .beta.-diketone of the formula wherein R1 and R2 are selected from the group consisting of hydrogen, an alkyl radical having from 1 to 10 carbon atoms and an aryl radical; and R3 and R4 are selected from the group consisting of hydrogen and a methyl radical.

2. The process of Claim 1 in which said .beta.-diketone derivative is 2,4-pentanedione.

3. The process of Claim 1 in which said .beta.-diketone dervative is 1-phenyl-1,3-butanedione.

4. The process of Claim 1 in which said .beta.-diketone derivative is 1,3-diphenyl-1,3-propanedione.

5. The process of Claim 1 in which said .beta.-diketone derivative is 1,1,1,5,5,5-hexafluoro-2,4-pentanedione.

6. The process of Claim 1 in which said .beta.-diketone derivative is 1-chloro-2,4-pentanedione.

7. The process of Claim 1 in which said .beta.-diketone derivative is 3-methyl-2,4-pentandione.

8. The process of Claim 1 in which said .beta.-diketone derivative is 4,6-undecanedione.

9. The process of Claim 1 in which said complex catalyst is present at a concentration of from about 0.00001 to about 0.1 mole per liter of the reaction medium.

10. The process of Claim 1 in which said complex catalyst is present at a concentration of from about 0.00005 to about 0.005 mole per liter of the reaction medium.

11. The process of Claim 1 in which said strong acid is sulfuric acid.

12. The process of Claim 1 in which said strong acid is hydrochloric acid.

13. The process of Claim 1 in which a combination of the complex catalyst and palladium ion is used as a catalyst.

14. The process of Claim 1 in which a combination of the complex catalyst and silver ion is used as a catalyst.

15. The process of Claim 1 in which a combination of the complex catalyst and manganese ion is used as a catalyst.

16. The process of Claim 1 in which a combination of the complex catalyst and lead ion is used as a catalyst.

17. The process of Claim 1 in which a combination of the complex catalyst and thallium ion is used as a catalyst.