Copper-catalyzed chlorination and condensation of acetylene and dichloroacetylene

Article abstract of DOI:10.1016/S0045-6535(99)00272-6

The chlorination and condensation of acetylene at low temperatures is demonstrated using copper chlorides as chlorinated agents coated to model borosilicate surfaces. Experiments with and without both a chlorine source and borosilicate surfaces indicate the absence of gas-phase and gas-surface reactions. Chlorination and condensation occur only in the presence of the copper catalyst. C₂ through C₈ organic products were observed in the effluent; PCDD/F were only observed from extraction of the borosilicate surfaces. A global reaction model is proposed that is consistent with the observed product distributions. Similar experiments with dichloroacetylene indicate greater reactivity in the absence of the copper catalyst. Reaction is observed in the gas-phase and in the presence of borosilicate surfaces at low temperatures. The formation of hexachlorobenzene is only observed in the presence of a copper catalyst. PCDD/F were only observed from extraction of the borosilicate surfaces. A global reaction model is proposed for the formation of hexachlorobenzene from dichloroacetylene. (C) 2000 Elsevier Science Ltd.

Full text of DOI:10.1016/S0045-6535(99)00272-6

Chemosphere 40 (2000) 1297±1303
Copper-catalyzed chlorination and condensation of acetylene
and dichloroacetylene
a,
Philip H. Taylor , Andreas Wehrmeier , Sukh S. Sidhu , Dieter Lenoir
b
a
b,*
*
,
b
K.-W. Schramm , A. Kettrup
b
a
Environmental Sciences and Engineering Group, University of Dayton Research Institute, 300 College Park, Dayton, OH 45469-0132,
USA
b
GSF ± National Research Center for Environment and Health, Institute for Ecological Chemistry, Ingolst a dter Landstr. 1, D-85764
Neuherberg, Germany
Received 30 March 1999; accepted 7 June 1999
Abstract
The chlorination and condensation of acetylene at low temperatures is demonstrated using copper chlorides as
chlorinated agents coated to model borosilicate surfaces. Experiments with and without both a chlorine source and
borosilicate surfaces indicate the absence of gas-phase and gas-surface reactions. Chlorination and condensation occur
2 8
only in the presence of the copper catalyst. C through C organic products were observed in the e‚uent; PCDD/F were
only observed from extraction of the borosilicate surfaces. A global reaction model is proposed that is consistent with
the observed product distributions. Similar experiments with dichloroacetylene indicate greater reactivity in the absence
of the copper catalyst. Reaction is observed in the gas-phase and in the presence of borosilicate surfaces at low tem-
peratures. The formation of hexachlorobenzene is only observed in the presence of a copper catalyst. PCDD/F were
only observed from extraction of the borosilicate surfaces. A global reaction model is proposed for the formation of
hexachlorobenzene from dichloroacetylene. Ó 2000 Elsevier Science Ltd. All rights reserved.
Keywords: Acetylene; Dichloroacetylene; Chlorination; Condensation; Hexachlorobenzene; PCDD/F
1
. Introduction
nation reactions. In the Deacon reaction, HCl is oxi-
dized in the presence of copper salts to molecular
Recent studies indicate that copper species play an
2
chlorine (Cl ). Chlorine reacts with acetylene at tem-
important role in the thermal formation of chlorinated
combustion by-products and in thermal condensation
reactions of aliphatic compounds (Froese and Hutzin-
ger, 1994, 1996a,b). Copper chlorides have been shown
to play a predominant role in surface-catalyzed chlori-
peratures above 450°C to yield tetrachloroethylene
(Chloberag, 1950; Fruhwirth and Walla, 1940). Cupric
2
chloride (CuCl ) can act directly as a chlorinating agent
by a ligand-transfer-oxidation mechanism (Nonhebel,
1970). In gas-surface reactions copper species are con-
sidered among the most e€ective catalysts in thermal
formation of chlorinated combustion by-products, e.g.,
polychlorinated dibenzo-p-dioxins (PCDD) and -furans
*
Corresponding authors. Tel.: +1-937-229-3604; fax: +1-
(
PCDF) (Addink and Olie, 1995 and references therein).
9
8
37-229-2503 (P.H. Taylor), Tel.: +49-89-3187-2960; fax: +49-
9-3187-3371 (D. Lenoir).
E-mail addresses: taylorp@udri.udayton.edu (P.H.
Froese and Hutzinger (1996b) have shown that acetylene
in the presence of cupric oxide (CuO) and HCl forms
chlorinated benzenes, phenols and PCDD/F at 600°C.
Taylor), lenoir@gsf.de (D. Lenoir).
0045-6535/00/$ - see front matter Ó 2000 Elsevier Science Ltd. All rights reserved.
PII: S 0 0 4 5 - 6 5 3 5 ( 9 9 ) 0 0 2 7 2 - 6

1
298
P.H. Taylor et al. / Chemosphere 40 (2000) 1297±1303
The objectives of this study were investigations of the
role of CuCl and CuO in molecular growth reactions of
2 8
PCDD/F. The procedures for the analysis of the C ±C
2
organics in the reactor e‚uent have been described in
detail in a prior publication (Wehrmeier et al., 1998).
For PCDD/F analysis (Schramm et al., 1995), the
acetylene and dichloroacetylene using model borosilicate
surfaces. It is shown that these surfaces reduce the
temperature required for chlorination and/or conden-
sation from 700°C (gas-phase) to temperatures as low as
1
3
borosilicate foam was removed and then spiked with
C
internal standards prior to 24 h soxhlet extraction in
toluene. High resolution open column chromatography
was used to separate the compounds of interest from
interferences. A small quantity of the sample, between 1
and 3 ll, was injected into a high resolution GC-MS
(Finnigan MAT 95, resolution ˆ 10 000). The injector
was programmed as follows: 120°C, 12°C/s to 280°C
1
50°C. The formation of PCDD/F from both C
Cl is also indicated from HRGC/MS analyses of
surface extracts. Global reaction mechanisms for both
acetylene and dichloroacetylene involving CuCl and
cuprous chloride (CuCl) intermediates are presented.
2 2
H and
C
2
2
2
(
10 min hold), then heat at 12°C/s to 300°C (10 min
2
. Experimental
hold). The transfer line temperature was 260°C. The
following GC column was used: Rtx 2330 (60 m, 0.25 mm
ID, 0.1 l ®lm thickness). The GC temperature program
was as follows: 90°C (hold 15 min), 25°C/min ± 180°C,
then 2°C/min to 260°C (30 min hold). The column head
pressure was 24 psi. Analysis of PCDD/F was conducted
in the SIM mode. The MSD scanned for the parent ion
(M) and the parent ion plus 2 ꢁM ‡ 2† of the compounds
of interest. Assumptions for quanti®cation of PCDD/F
All experiments were conducted using an isothermal,
fused silica gas±solid ¯ow reactor equipped with an in-
line GC±MS analytical system for analysis of stable re-
action products. The experimental approach has been
described previously (Wehrmeier et al., 1998). A brief
summary is presented here.
A cylindrical borosilicate foam (1.5±2.0% Na
.5% K O, 9.5±10.0% B , 9.0±9.5% Al , 77±80%
SiO
2
O, 1.0±
1
2
1
2
2
O
3
2
O
3
include that: (i) response factors and recoveries of
C
1
3
2
†, with a length of 5 cm, a diameter of 7 mm, and a
and C-labeled congeners are equal; (ii) response factors
and recoveries within a certain isomer group are equal;
(iii) response factors and recoveries of mixed PCDD/Fs
are equal to those of their fully chlorinated analogs.
pore size of 200 lm was used as the catalyst support.
Studies were performed with two di€erent copper cata-
2 2
lysts, CuCl and CuO. CuCl was applied to the support
by impregnation with a 20% aqueous solution of CuCl
followed by drying at 120°C for 1 h (Bond et al., 1991).
The CuO-coated foam was prepared by calcining an
2
3. Results
3 2
impregnated Cu(NO ) foam at 480°C for 16 h in air.
Cupric chloride was thermally treated at 250°C for four
days in a ¯ow of oxygen-free helium to remove sub-
stantial amounts of chlorinated compounds, especially
hexachlorobenzene. Technical grade acetylene was ob-
tained from a local compressed gas supplier (Air Prod-
ucts). Acetylene was withdrawn from the cylinder under
sub-ambient temperatures to minimize the amount of
acetone impurity (ꢀ1%). Dichloroacetylene was syn-
thesized using methods reported in the literature (Pieli-
chowski and Popielarz, 1984).
2
Reactions of acetylene on CuCl -impregnated
borosilicate foams produced a variety for chlorinated
organic compounds. This system was able to chlorinate
acetylene to form chlorinated C
carbon numbered condensed products up to C
2
compounds. Even
were
8
observed in the gas-phase (Fig. 1). The most striking
feature in the distribution of reaction products was the
high degree of chlorination. A majority of products were
perchlorinated. A surprising observation was the lack of
unchlorinated acetylene polymerization products, e.g.,
vinylacetylene, benzene, ethynylbenzene and naphtha-
lene. Furthermore, cracking products and compounds
with an odd number of carbon atoms were not detected.
CuO was also tested for its catalytic activity towards
acetylene condensation and chlorination in the acety-
lene±CuO/BS and acetylene/HCl±CuO/BS system, re-
spectively. Gas-phase reaction products formed in the
acetylene/HCl±CuO/BS system were observed in similar
In separate experiments, acetylene or dichloroacety-
lene (1100 Æ 200 ppm in 4% O
2
in helium, 167 micro-
moles total) was ¯owed over borosilicate (BS)
impregnated with 300 Æ 75 lmol of CuO or
3
2 2 2
50 Æ 80 lmol of CuCl . In the C H CuO experiments,
the reaction gas also contained 1100 Æ 200 ppm HCl to
provide a chlorine source. Fuel-lean conditions were
maintained to prevent soot formation which was re-
ported to be problematic in previous studies (Froese and
Hutzinger, 1996a,b). Experiments were conducted over a
temperature range of 150±500°C, with a gas-phase resi-
dence time over the support of 1±10 s and a total reac-
tion time of 60 min. Gas-phase products were analyzed
using both in-line and o€-line GC-MS; the catalyst foam
was subjected to o€-line HRGC-MS analysis for trace
amounts as in the acetylene±CuCl
parable temperatures at and above 300°C. In contrast to
the acetylene±CuCl /BS system, no reaction products
2
/BS system at com-
2
were detected at temperatures below 300°C. The two
systems investigated without adding copper species,
acetylene±BS and acetylene/HCl±BS, did not result in
any reaction products at temperatures up to 500°C.

P.H. Taylor et al. / Chemosphere 40 (2000) 1297±1303
1299
BS system increased the total product yield. The same
reaction products were formed, but the distribution was
shifted towards higher chlorinated compounds, i.e., tri-
chloroethylene was not detected. A few minor reaction
products were not quanti®ed; these products are not
included in summation of product yields. These prod-
ucts included tetrachloromethane, pentachloroethane,
and mono- through pentachlorobenzene.
Changes in product yields for the two systems cor-
responded to changes of the surface. The color of dry
CuCl
was loaded onto the borosilicate. Heating this system to
00°C did not show any changes in color, but CuCl
2
is yellow±brown and it did not change when it
3
2
started to sublime from the foam above 300°C and the
loaded borosilicate reverted back to its original white
color when it was heated to 500°C. This e€ect indicated
Fig. 1. Major gas-phase products (mol%) for the reaction of
acetylene on CuCl /BS at di€erent residence times.
total ˆ 167 lmol; ‰HClŠ
2
a loss of CuCl from the borosilicate at elevated tem-
2
peratures. The CuO-mediated borosilicate was black.
This appearance did not change upon heating to 500°C.
However, upon addition of HCl, the color of the foam
turned yellow±brown at temperatures above 300°C, in-
dicating that CuO started to react with HCl at 300°C,
[
C
2
H
2
]
ˆ 167 lmol; ‰CuCl
2
Š ˆ
total
0
3
44 Æ 80 lmol; [C
2
Cl
2
]
total ˆ 167 lmol; T ˆ 300°C; t ˆ 2:0 s.
r
Reactor gas: 4% O
2
in He.
Acetylene was unreactive in the gas phase at tempera-
tures between 200°C and 500°C.
The total yield of reaction products was a function
2
which resulted in formation of CuCl .
Cu (I) and Cu (II) species were identi®ed from post-
experiment XPS analysis of the borosilicate surfaces.
The fraction of Cu (I) species increased from 30% at
150°C to 40% at 350°C. Cu (I) and Cu (II) species
containing chlorine were identi®ed from XPS analysis of
the acetylene/HCl-CuO/BS experiments, lending credi-
of both temperature and residence time. For the acet-
2
ylene±CuCl /BS system, reaction started at tempera-
tures below 150°C and rose to maximum yields at
about 300°C (Wehrmeier et al., 1998). Yields decreased
at higher temperatures. No reaction products were
produced at 500°C. Reaction products for the acety-
lene/HCl±CuO/BS system were only found at and
above 300°C with maximum yields at 400°C. In con-
2
bility to the hypothesis that CuCl/CuCl is the dominant
chlorinating system in these experiments.
A series of experiments with dichloroacetylene were
conducted to determine if the major reaction products
trast to the acetylene±CuCl
2
/BS system, signi®cant
were similar to the acetylene±CuCl
lustrated in Fig. 3, a distinct similarity was observed.
Gas-phase experiments with C Cl
at 300°C indicated
signi®cant dimerization of the starting material
Cl conversion) with tetrachlorovinyl-
2
/BS system. As il-
amounts of reaction products were formed at 500°C.
Approximately 9 mol% of acetylene was transformed
to chlorinated and condensed reaction products in the
2
2
presence of a CuCl
00°C. In the presence of 1100 ppm HCl, yields rose to
just over 10 mol%.
2
-impregnated borosilicate foam at
(ꢀ8 mol% C
2
2
3
acetylene the major product. In the presence of the
catalyst support, signi®cant changes in reactivity were
observed with tetrachloroethylene, tetrachlorovinyl-
acetylene, and hexachlorobutadiene the major products
The time-dependent studies indicated that chlorina-
tion and condensation reactions are fast processes,
which readily occur at t
maximum rate at t
ˆ 1:5±2:0 s. Product yields for C
and C species generally decreased for residence times
greater than 2 s. Yields of C species achieved a steady-
r
ˆ 1:0 s and achieve their
(ꢀ15 mol% C
2 2
Cl conversion). Addition of CuO to the
r
2
surface resulted in further changes in reactivity with
tetrachloroethylene, tetrachlorovinylacetylene, hexa-
chlorobutadiene, and hexachlorobenzene as the major
4
6
state or decreased with increasing reaction time. The
expected shift in molecular weight distribution of reac-
tion products with increasing residence time was not
observed.
products (ꢀ9 mol% C
2 2
Cl conversion). The presence of
CuO resulted in increased yields of hexachlorobenzene
at the expense of the other products. These experiments
demonstrate that condensation of dichloroacetylene
(beyond dimerization) does not readily occur in the
absence of the copper catalyst. The acetylene and di-
chloroacetylene experiments clearly indicate that chlo-
The main reaction products formed in the acetylene±
CuCl /BS system at 300°C are illustrated in Fig. 2. Re-
2
action products with a lower degree of chlorination (e.g.,
trichloroethylene) were predominantly formed at higher
temperatures. Maximum product yields were typically
6
rination and formation of C and other chlorinated
aromatic compounds at these low temperatures
requires the copper catalyst.
2
produced at 300°C. Adding HCl to the acetylene-CuCl /

1
300
P.H. Taylor et al. / Chemosphere 40 (2000) 1297±1303
Fig. 2. Major gas-phase products (mol%) for the reaction of acetylene on CuCl
total ˆ 167 lmol; ‰CuCl Š0 ˆ 344 Æ 80 lmol; t ˆ 2:0 s. Reactor gas: 4% O in He. Error bars represent relative standard devi-
ations in the product measurements.
2
/BS at 150°C, 300°C and 400°C, respectively.
[
C
2
H
2
]
2
r
2
extraction of the catalyst surface as illustrated in Figs. 4
and 5 for acetylene and dichloroacetylene, respectively.
The high yields of PCDD/F extracted from the surface
suggests that signi®cant levels, i.e., ꢀ10%, should have
been observed in the gas-phase. This expectation is de-
rived from results of municipal waste incinerators. The
ratio of PCDD/F remaining on ¯y ash and further
transferred by the ¯ue gas at the ESP unit at 300°C is
estimated in the range of 10:1 (Hutzinger and Fiedler,
1
993). The lack of gas-phase detection of PCDD/F
suggests that copper-coated borosilicate surfaces may
not be a good model for ¯y ash-mediated formation of
PCDD/F from the perspective of gas±solid partitioning.
The lack of gas-phase detection of chlorophenols is also
consistent with this observation.
For the acetylene experiments, the pattern of isomers
of tetra- to heptachloro dibenzo-p-dioxins, the PCDD/
PCDF ratio (<1), and the temperature of maximum
yields (300±400°C) are consistent with published data
from various full-scale combustors (Lenoir et al., 1998;
Wehrmeier et al., 1998). The data for the tetrachlo-
rodibenzo-p-dioxin isomers obtained at a factor of 9
higher initial acetylene concentration is shown in Fig. 6.
This result demonstrates the relevance of these experi-
ments to full-scale incineration systems. It should also be
mentioned that the residence times examined in our
experiments are in the same range as observed by
Fig. 3. Major gas-phase products (mol%) for the reaction of
dichloroacetylene on CuO/BS at 300°C. [C Cl
2
2
]
total ˆ 167 lmol;
in He.
‰
CuOŠ ˆ 300 Æ 75 lmol; t
r
ˆ 2:0 s. Reactor gas: 4% O
2
0
Error bars represent relative standard deviations in the product
measurements.
Chlorophenols and PCDD/F were not observed in
the reactor e‚uent. However, signi®cant levels of many
PCDD/F congeners were observed from subsequent

P.H. Taylor et al. / Chemosphere 40 (2000) 1297±1303
1301
°
°
°
Fig. 4. Homologue pro®le for surface-bound PCDD/F following acetylene experiments at 200 C, 300 C, and 400 C. Also shown is the
result for a blank borosilicate surface. [C
2
H
2
]
total ˆ 167 lmol; ‰CuCl
2
Š0 ˆ 344 Æ 80 lmol; t
r
ˆ 2:0 s. Reactor gas: 4% O
2
in He.
Fig. 5. Homologue pro®le for surface-bound PCDD/F following dichloroacetylene experiments at 300°C. [C
2
Cl
2
]
total ˆ 167 lmol;
‰
CuOŠ ˆ 300 Æ 75 lmol; t
r
ˆ 2:0 s. Reactor gas: 4% O
2
in He.
0
Faengmark et al. (1994) for PCDD/F formation in a
pilot-plant burning municipal waste.
PCDD/F occurs on the surface, based on surface
retention times of up to 60 min. In fact, one can ratio-
nalize the larger yields of less chlorinated PCDD/F from
acetylene with the observation of partially chlorinated
aromatic intermediates, e.g., mono- through pentachlo-
robenzene. This may be followed by the dissociative
adsorption of these compounds with the formation of
surface-bound partially chlorinated phenols.
Comparison of the acetylene and dichloroacetylene-
derived PCDD/F homologue pro®les, cf. Fig. 7, indicates
substantial di€erences. Dichloroacetylene preferentially
forms OCDF. Yields of OCDF were more than a factor
of 2±3 larger for dichloroacetylene than acetylene and
acetylene/HCl. However, as the level of chlorination
decreased, relative PCDD/F yields become increasingly
larger from acetylene. PCDD/F dechlorination reactions
have been o€ered as an important mechanism in ratio-
nalizing PCDD/F homologue pro®les from both labo-
ratory experiments using actual ¯y ashes and full-scale
data. The results presented here appear inconsistent with
this mechanism. The dichloroacetylene data do not
support the contention that signi®cant dechlorination of
4. Discussion
The following experimental observations indicate
that acetylene is chlorinated prior to surface-catalyzed
condensation:

1
302
P.H. Taylor et al. / Chemosphere 40 (2000) 1297±1303
Fig. 6. Concentrations of tetrachlorodibenzo-p-dioxin isomers following acetylene experiments at 300°C. [C
CuCl ˆ 2:0 s. Reactor gas: 4% O in He.
Š0 ˆ 344 Æ 80 lmol; t
2
H
2
]
total ˆ 1510 lmol;
‰
2
r
2
Consistent with our experimental results and by anal-
ogy with mechanisms found in solution chemistry, we
proposed the following global reaction mechanism for
the gas-surface chlorination/condensation reaction of
acetylene on copper species (Wehrmeier et al., 1998).
Acetylene is chlorinated by CuCl
oxidation mechanism to mono- and dichloroacetylene
and other less unsaturated chlorinated C compounds.
2
in a ligand transfer
2
Chlorinated acetylenes then form oligomers in a sur-
face-catalyzed reaction. Stahl et al. (1986) have shown
that reactive dichloroacetylene is stabilized in metal
complexes. These metal-dichloroacetylene complexes
react with additional dichloroacetylene to form chlori-
nated metallacylopentadienes (S u nkel, 1990, 1991),
known intermediates in dichloroacetylene condensation
reaction. According to the Glaser and Cadiot±Cho-
Fig. 7. Surface concentrations of Cl
lowing acetylene, acetylene + HCl, and dichloroacetylene ex-
periments at 300°C. [C
lmol; [C Cl
CuOŠ ˆ 300 Æ 75 lmol; t
4 8
DD/F to Cl DD/F fol-
2
H
2
]
total ˆ 167 lmol; [HCl]total ˆ 167
‡
dikiewicz reaction, Cu complexes are possible catalysts
2
2
]
total ˆ 167 lmol; ‰CuCl
2
Š ˆ 344 Æ 80 lmol;
0
(
Chodikiewicz, 1957). Chlorinated metallacylopentadi-
ene then forms chlorinated butadienes in oxidative
chlorination reaction with CuCl or reacts with
‰
r
ˆ 2:0 s. Reactor gas: 4% O
2
in He.
0
2
·
·
·
·
·
No acetylene polymerization products were found
with either catalyst investigated.
dichloroacetylene in an insertion or Diels±Alder type
reaction to form chlorinated benzenes (S u nkel, 1990,
1991).
Condensed reaction products were only found with a
chlorine source present.
A similar mechanism involving CuCl can be envi-
sioned for formation of hexachlorobenzene from
dichloroacetylene, cf., Fig. 8. Interactions between the
d orbitals of the Cu and the p electrons of the dichlo-
roacetylene result in the formation of chlorovinyl radical
intermediates stabilized by the adjacent copper (see
Scheme 1).
Yields of reaction products increased with additional
chlorine.
Reaction products were predominantly perchlorinat-
ed.
Major products from dichloroacetylene/BS/CuO
2
were similar to those for acetylene/BS/CuCl .

P.H. Taylor et al. / Chemosphere 40 (2000) 1297±1303
1303
combustion by-products from forming is an important
step in reaching these goals.
Scheme 1.
Acknowledgements
This work was partially supported by the National
Science Foundation, Grant No. CTS-9525783. The au-
thors like to thank Harald Bartl for his help in the
laboratory and additional computer work and Rich
Striebich for the quali®cation of the volatile reaction
products.
References
Addink, R., Olie, K., 1995. Environ. Sci. Technol. 29, 1425±
1435.
Bond, G.C., Namijo, S.N., Wakeman, J.S., 1991. J. Molec.
Catal. 64, 305±319.
Chloberag, 1950. Chlorbetrieb Reinfelden, DBP. 868294.
Chodikiewicz, W., 1957. Ann. Chim. (Paris) 13, 819±869.
Faengmark, I., Stroemberg, B., Berge, N., Rappe, C., 1994.
Environ. Sci. Technol. 28, 624±632.
Fig. 8. Catalytic cycle for formation of hexachlorobenzene
from dichloroacetylene via copper-stabilized chlorovinyl
radicals.
Froese, K.L., Hutzinger, O., 1994. Chemosphere 28, 1977±
1
987.
Froese, K.L., Hutzinger, O., 1996a. Environ. Sci. Technol. 30,
98±1008.
9
A stable desorbed product, hexachlorobenzene, is
formed by ring closure. The formation of hexachloro-
benzene as the only C product from dichloroacetylene
Froese, K.L., Hutzinger, O., 1996b. Environ. Sci. Technol. 30,
1009±1013.
Fruhwirth, O., Walla, H. 1940. Donau Chemie AG., Erf., DBP.
6
7
34024.
reactions in the presence of the copper catalyst is ex-
perimental support for this mechanism.
Hutzinger, O., Fiedler, H., 1993. Chemosphere 27, 121±129.
Lenoir, D., Wehrmeier, A., Kaune, A., Zimmermann, R.,
Taylor, P.H., Sidhu, S., 1998. Environ. Eng. Sci. 15, 37±48.
Nonhebel, D.C., 1970. J. Chem. Soc. (Special Publication.) 24,
5
. Summary
409±437.
Pielichowski, J., Popielarz, R., 1984. Synthesis 5, 433±434.
Schramm, K.-W., Merk, M., Henkelmann, B., Kettrup, A.,
1995. Chemosphere 30, 2249±2257.
Copper is mostly present in waste streams as CuO.
Our results demonstrate that temperatures in the post-
combustion zones should be quenched immediately be-
Stahl, K., Weller, F., Dehnicke, K.Z., 1986. Anorg. All. Chem.
533, 73±82.
2
low 300°C to prevent CuCl/CuCl formation, an active
S u nkel, K., 1990. J. Organomet. Chem. 391, 247±257.
S u nkel, K., 1991. Chem. Ber. 124, 2449±2451.
Wehrmeier, A., Lenoir, D., Sidhu, S.S., Taylor, P.H., Rubey,
W.A., Kettrup, A., Dellinger, B., 1998. Environ. Sci.
Technol. 32, 2741±2748.
catalyst system that may be in part responsible for the
formation of these toxic combustion by-products. The
mechanisms of chlorination and condensation discussed
herein provide a tool towards minimization of these
compounds in the e‚uents of incinerators. With gov-
ernment regulations constantly seeking lower emissions
for these compounds, this method of preventing toxic
Wehrmeier, A., Lenoir, D., Schramm, K.-W., Zimmermann,
R., Hahn, K., Henkelmann, B., Kettrup, A., 1998. Chemo-
sphere 36, 2775±2801.