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I
WILLIAM W. WINSHIP
The Thermal Syndicate, Ltd., New York, N. Y
Vitreous s i l i c a has been used and specified
by many workers in the field of organic
(chlorination) and inorganic (chloridizing)
reactions with chlorine.
Indifference to severe temperature condi-
tions, to chlorine even in its nascent condi-
tion, and to chlorinated organic compounds
and most metallic chlorides, together with
noncatalytic properties and, in the trans-
HEMICAL reactions utilizing chlorine and its com-
pounds
on
the production scale entail somewhat unusual
problems, often involving considerations of photo-
chemistry and catalysis in addition to the more frequent fac-
tors of temperature and chemical resistance.
Inmany of these operations metals and alloys lack the re-
quired resistance to wet chlorine and hydrochloric acid at high
temperatures, and most ceramics are deficient with respect
to homogeneity, purity,
or
resistance to thermal shock.
Phosgene is a useful source of chlorine for both chlorina
tion and chloridizing reactions and
has
been found especially
efficient in the la tter field. The chloridizing of mineral
materials in admixture with carbon probably involves the
reversible reaction
CO +
Clg
= COCL.
The reducing ac-
tion of carbon monoxide liberated during the decomposition
may serve a useful purpose in such chloridizing technique
~~~~~~~~~~~~~
ob
~~~~~~~~
Silica
Judged by the criteria of chemical, thermal, catalytic, and
optical requirements, vitreous silica combines the desired
properties in
an
unusual degree. The transparent variety
(quartz glass) and the translucent and opaque grades (fused
silica) are identical in homogeneity and chemical properties
and similar in thermal, catalytic, and most other physical
characteristics.
The clear variety is unusually transparent to ultraviolet
light
(a
characteristic lacking in the translucent and opaque
grades), transmitting down to about 2000
A It
is also
highly transparent in the visible and infrared ranges.
CHEMICALRESISTANCE.In chlorination and chloridizing
practice, chlorine and
its
compounds generally have
no
effect
on vitreous silica up to its useful temperature limit (1000-
llOOo C.). Some alkali metal chlorides are an exception;
for example, Maier (60) reported that fused lithium chloride
is rather active in dissolving silica.
Fink
and de Marchi
(28)
investigated the effect of certain
chloridizing reactions
on
fused silica
at
about 900' C. and
found it apparently due to the presence of sulfur compounds,
parent variety, high transmission of actinic
light, provide a chemical engineering ma-
terial valuable for reactor construction and
for equipment required in hydrogen chlo-
ride, hydrochloric acid, and chloride re-
covery.
A n
extension
of
the use of fused
silica and quartz glass
on an
ndustrial scale
is suggested
along
ines of application
which
have already proved their value.
since the maximum was reached a t the temperature where the
latter dissociated.
Von Ktigelgen and Seward
48)
stated that when silica is
mixed with carbon, a 2-hour treatment
at
900 C. chlorinates
only 1 per cent of the silica present.
The surface resistance
of fused silica apparatus under similar circumstances will
greatly exceed the resistance to chemical attack of finely
powdered material; furthermore, reaction
on
powdered
materials may be due to the presence of impurities.
Nascent chlorine as liberated during the decomposition of
phosgene is the most reactive form of this element. The
complete indifference of silica to chlorine is strikingly demon-
strated in the following table by Chauvenet reproduced
by
Dyson (18) which shows the reaction temperatures of car-
bonyl chloride with various metallic oxides and indicates the
resulting anhydrous chlorides:
Temp.,
Oxide O C. Chloride
Tungstio
Vanadio
Iron
Tantalic
Titanio
Ziroonia
Tin
A u
m
n
a
Magnesia,
Zinc
Beryllia
Tzmp.,
Oxide C. Chloride
Manganese
Uranium
Barium
Nickel
Chromium
Cerium
Yttria
Lanthanum
Thoria
Silioa
460 MnClr
450 UC14
600
BaCln
560 NiClr
600 CrClr
600 CeCL
600
YC4
600 LsCL
650 ThCh
Nore-
....
aotion
While investigating the thermal decomposition of phosgene,
Ingelson
(86)
found that glass was attacked by the chlorine
set free; therefore, vitreous silica had to be used
as
a container
for the gas.
THERMALESISTANCE.Vitreous silica apparatus can be
used continuously without loss of strength at temperatures
up to its crystallization point, 1000-1100' C. The upper
limit is favored by the absence of strongly reducing gases,
while the lower limit may be depressed by certain substances
(for example, sodium tungstate, vanadic acid, or sodium and
potassium chlorides) which tend to accelerate
this
so-called
devitrification.
On the other hand, in a favorable chemical environment
143
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144 I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y Vol.
33,
No. 2
vitreous silica equipment will withstand operating tem-
peratures up to 1400 C. if i t is not allowed to fall below the
low-temperature transition point at 300 C.
FIGURE
.
FUSED
ILICA HLORINATORSSEMBLY
OPTICALCHARACTERISTICS.n appearance similar to a
high-quality colorless glass, quartz glass analyzing (like all
vitreous silica products of high quality) about 99.8 per cent
SiOz possesses high optical transmission up to its crystalliza-
tion point, from the long infrared range through the short
ultraviolet.
It is therefore particularly useful where actinic
light is employed to accelerate reactions or to supply visi-
bility under temperature conditions impossible with glass.
On account
of
its high electrical resistance at elevated tem-
peratures, vitreous silica offers special advantages for insulat-
ing current leads, arcs, and other elements in processes
utilizing electrical forces in the conversion of hydrocarbon
compounds by chlorination. The low expansion of vitreous
silica, which is much less than that of metals or alloys,
demands special care when assembling silica apparatus with
other chemical plant details.
Lacy (46) showed a chlorinator comprising cylindrical iron
shells with cylindrical silica linings, the spaces between being
filled with finely ground flint (Figure
1 .
Ground fused silica
might be substituted for the flint to give the low expansion
characteristic
of
fused silica equipment.
Groll and Hearne
29)
mentioned four methods of accelerat-
ing hydrocarbon chlorination reactions: radiation by actinic
light, presence of a catalyst , induction by simultaneous
chlorine addition, and heat . The reacting gases may be pre-
heated before mixing, or the mixed gas may be passed through
a heated tube.
Egloff said that actinic light, heat, and catalysts have
been extensively used to accelerate the chlorination of the
paraffin hydrocarbons (19) but posed
a
question as to the ac-
tual wave lengths of Iight which are effective. He calls atten-
tion t o the zero catalytic effect of fused silica in these reactions.
The thermal conductivity of vitreous silica (0.0035 calorie/
second/cm./sq. cm./ C. for the transparent grade and
0.0025 for the nontransparent) is excellent and, in general,
increases with rising temperature. But the thermal property
of outstanding technical importance is its exceptionally low
expansion and contraction with temperature change, which
ensures immunity to thermal shock in a degree possessed by
no other ceramic material.
Not only is the linear coefficient of 0.00000054 per C.
smaller than that of any other manufactured product, but it
is
practically constant and gives a straight-line curve up
t o
about 1100 C. Vitreous silica can accordingly be employed
over this entire temperature range without thermal strains
due to critical temperature zones.
CATALYTICHARACTERISTICS.Vitreous silica is chemically
inert and homogeneous and lacks the property of
a
practical
adsorbent owing to its low retentivity 56). While various
porous forms of silica have been recommended as catalysts
in Chlorination processes, especially when preheated to high
temperatures
48),
the value of vitreous silica in such opera-
tions is rather a s a catalyst carrier, because of its catalytic,
chemical, and thermal inertness. The essentially noncata-
lytic character of vitreous silica apparatus, combined with its
resistance
t o
chemical attack, is of the highest importance in
safeguarding against secondary reactions involved in organic
chemical operations generally.
-
I
I
FIGURE .
FUSEDSILICAS-BENDREACTIONYSTEYOR
COUNTERCURRENTIQUID-PHASEHLORINATIONS
Chlorination reactions are often highly exothermic (5 4)
and require reactors capable of resisting sudden cooling;
or
the chlorinating vessels may have to be heated in order
t o
bring about the reaction (19, 46). Vitreous silica re-
action vessels may be air- or water-cooled, or may be heated
externally by fuel gases; and tubular reactors may be wound
with resistance wire for electrical heating in continuous
flow
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February, 1941
145
operations, temperature gradients being maintained by vary-
ing the winding on the same tubular vessel.
Chlorination processes may require that the chlorine gas
be preheated and mixed with the hydrocarbon vapor, and that
the mixed vapors be passed through a heated zone where
their temperature is gradually increased (21).
Fused silica
tubes with separate windings of resistance wire offer obvious
advantages for such operations, and vitreous silica equip-
ment will also provide for collecting and absorbing the
separated hydrogen chloride.
Wiezevich and Vesterdal (71) suggested the use of glass
vessels in the absence of iron to obtain the best yields in
chlorinating various petroleum products.
Obviously the use
of fused silica would permit the employment of larger indi-
vidual units, under more severe temperature conditions.
In countercurrent chlorinations of organic liquids, vitreous
silica packed towers may be water-cooled to remove reaction
heat. A more efficient type of apparatus for such operations
is the flattened S-bend absorber (Figure
2).
Organic chlorinations may utilize the direct action
of
chlo-
rine gas, or use hydrogen chloride or phosgene as the chlorin-
ating agent. Groggins and Newton noted that vapor-phase
reactions, especially those employing light
as
an accelerant,
require equipment very different from that used for liquid-
phase chlorinations (28) and mentioned fused silica as a suit-
able material of construction for the former.
Wet hydrochloric acid gas has always presented
a
difficult
engineering problem in developing vapor-phase chlorination
processes. Roka
(61)
pointed out that silica vessels enable
the chlorination of methane to be
effected a t high temperatures with
moist reaction gases. Moisture was
also claimed by Lacy to be advan-
tageous in manufacturing methyl
chloride (@), and he mentions the
use of vitreous silica equipment.
Vapor-phase reactions calling for
accurate temperature control in con-
tinuous operations may well be con-
ducted in vitreous silica tubeswound
with electrical resistance wire for
direct heating. A f l ing of ground
fused silica between tubing of the
same material and metal enclosing
cylinders offers possibilities of an
assembly for high-pressure high-
temperature endothermic reactions.
Carter and Coxe
12)
mentioned
the use of tubular chlorinators,
which may be made
of
fused silica
and maintained at 400-650 C. by
any suitable means, for producing
chloro derivatives of methane. In
the production of chlorinated hy-
drocarbon derivatives, Jackson,
Wainwright, and Hailes
(37)
speci-
fied an electrically heated silica
tube through which the reacting
vapors pass at 700 C. Heated
vitreous silica reaction vessels were
FIGURE. VITREOUS
SILICALECTRIC
M-
MERSION HEATER
also suggested by Lacy for manufacturing organic halogen
products
(46),
ncluding ethyl chloride (44).
The reaction of hydrocarbon gases with chlorine may be
promoted by passing the hot mixed gases through porous
plates
of
sintered fused silica
(16).
Such plates have recently
been offered for commercial use. Vitreous silica electric im-
mersion heaters (Figure 3) are particularly convenient for in-
ternally heating chlorination equipment in either gas- or
liquid-phase reactions.
In certain chlorination processes, notably the manufacture
of rubber hydrochloride
65),
pure dry hydrogen chloride
rather than chlorine is used as the halogenating agent. Satu-
rated hydrocarbons
(42)
may be chlorinated by reaction with
hydrochloric acid and oxygen a t temperatures up to
650
C.
Hydrogen chloride is
also
the reacting agent, with oxygen,
in producing chlorobenzene from benzene
(67);
and in some
modifications of the Friedel and Crafts reaction go ) , alumi-
FIGURE . FUSED
SILICABURNER OR
COMBUSTION OF
CHLORINE
N
HYDRO-
GEN
num chloride, reacting with hy-
drocarbons, yields hydrogen chlo-
ride which takes part in further
reactions. The presence of the
latter
also
appears to be essential
to the reaction of certain hydro-
carbons with aluminum chloride.
Hydrogen chloride hydrolysis
may be applied to organic com-
pounds and hydrogen chloride
as
a
hydrolyzer, and as
a
by-product
of hydrolysis may present a con-
siderable engineering problem
(2 ).
With larger sizes
of
vitreous
silica equipment now available i t
should be possible to extend the
use
of
this material on the plant
scale.
Hydrogen chloride for the pro-
duction of lower alkyl chlorides
must be of extreme purity, and
special precautions are necessary
to obtain the gas as free as pos-
sible from admixture with chlorine
and other permanent gases. A
patent describes the production of
such gas and its use with a suit-
able catalytic agent
39).
One
of the most important require-
ments in chlorinating rubber is
a supply of anhydrous hydrogen
chloride, which may be dried over
sulfuric acid or anhydrous calcium chloride (63). About
5
per cent of hydrogen chloride contained in the spent acid is
usually recoverable.
Large volumes of hydrogen chloride gas are evolved in in-
dustrial Friedel and Crafts reactions, and the corrosion prob-
lem is always present 41). In rubber chlorination, boiling
vessels must be employed
(69)
to remove hydrogen chloride
and free chlorine.
Egloff
20)
stated: In many of the reac-
tions of pure hydrocarbons in the presence of aluminum chlo-
ride, hydrogen chloride is
a
highly important component of th e
system. It may be added to the reaction or may be present
as a result of hydrolysis of the aluminum chloride by water,
or may arise
as
a product of the hydrocarbon reaction.
Hydrocarbon halides in the presence of steam and catalysts
may decompose to give hydrochloric acid and water vapors
48).
Hydrochloric acid may be formed in the thermal
purification
of
chlorinated hydrocarbons containing similar
compounds, in the presence of suitable dehydrogenation
catalysts (8). Methane will produce hydrogen chloride (IO)
by a highly endothermic reaction with sodium chloride, and
calcium, lithium, and potassium chlorides can be used simi-
larly. A tubular reactor with excess of water vapor should be
employed at 700-800 C.
(64)
n the synthesis of hydrochloric
acid by reaction of methane, water vapor, and chlorine.
Conditions of economy as well as sound engineering practice
require tha t the loss of chlorine as hydrogen chloride from
hydrocarbon halogenations be kept t o the minimum, and hy-
drochloric recovery systems are standard features of most halo-
genation processes. Hydrogen chloride liberated in hydro-
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carbon halogenations might profitably be decomposed and
the chlorine recirculated for further use. Patents 49,
66) cover methods for effecting this recovery. Here the con-
ditions of corrosion are severe, and proper choice of equip-
ment material is essential.
4i
FIGURE
.
FUSEDILICA ROTATINGURNACDOR ANEIYDROUS
METALLIC HLORIDERODUCTION
High-quality hydrochloric acid of 20 BB. strength suitable
for marketing is usually obtainable from the chlorination of
hydrocarbons. In some chlorination processes the liberated
hydrogen chloride may be recirculated with the gaseous mix-
ture through the reaction chamber 66); where hydrogen
chloride is the original reacting agent, this is especially prac-
ticable (67). A patent issued t o Ayres ( 2 ) illustrates a typical
vitreous silica absorption system used in recovering hydrogen
chloride from chlorinated solvent manufacture.
Water is particularly suitable as an absorbent for recover-
ing hydrogen chloride from chlorination processes, not only on
account of the high solubility of hydrogen chloride in it, but
because of i ts substantial immiscibility with most halogenated
organic products ( 2 2 ) . It s high heat capacity and latent heat
make it an effective cooling agent when used in small quanti-
ties to avoid excessive dilution of the hydrochloric acid
formed.
Methods have been devised for preventing the formation
of organic films on the absorbent
I ) ,
and for rectifying the
liquid mixture
of
chlorinated products and hydrochloric
acid to produce anhydrous hydrogen chloride 16). Fused
silica condensers arranged on the reflux principle enable
water cooling to be employed at temperatures impossible
with glass or stoneware equipment.
Hydrochloric acid separated in chlorination processes is
often obtained free from arsenic and sulfur compounds
(9)
and may be anhydrous (63). In gas-phase reactions, washing
with water is often sufficient to separate the hydrogen chloride
from residual organic gases 44). Hydrogen chloride produced
in liquid-phase reactions may be scrubbed with the make-up
hydrocarbon compound entering the process before absorption
in water
14).
Baxter suggested the separation of by-product hydrogen
chloride from admixed organic vapors by scrubbing in a tower
containing boiling water , the heat of reaction maintaining
the scrubbing solution a t about 110
C.
6). He claimed tha t
20 per cent hydrochloric acid can be
so
obtained. Thomas
(68) described the separation of hydrochloric acid from the
chlorination of pentane and i ts absorption in a countercurrent
fused-silica system, giving hydrochloric acid of 20 BB.
strength for sale.
In he production of hydrogen chloride for chlorination and
chloridizing processes, the combination of chlorine and hy-
drogen by combustion gives gas of high purity and high
strength. With gas supplies adjusted in proper ratio and ade-
quate cooling, a plant of this typ e will operate continuously
with the minimum of supervision.
Figure 4 shows a standard fused silica burner employed for
the combustion of chlorine in hydrogen, an excess of the la tter
gas
flowing through the outer tube. A vertical combustion
chamber and cooling equipment of the same material are
followed by absorbers if liquid hydrochloric acid is required.
~~~~~~~~~~~~~~~~
g raor[ynEliu:)
JpqPlreraricPera
Apparatus for chloridizing must ordinarily withstand tem-
peratures considerably higher than those encountered in or-
ganic chlorinations; the production of aluminum chloride,
for example, necessitates resistance to chlorine a t
1000
C.
41), tha t of beryllium chloride involves a temperature of
800
C.
( 7 2 ) ,
while zinc chloride can be formed from its ele-
ments a t 600-700
C.
(60).
Selective separation of metal chlorides by heating ores and
similar materials in the presence of chlorine has been carried
out at 1100 C. in separating chromium, nickel, and iron
values
(SI),
t 1050" for separating niobium and tantalum
64),a t
900
in the case of chromite (87), a t
900
for obtain-
ing aluminum chloride from clay or bauxite
(@),
a t
700-900
for separating iron and nickel
(SO),
and at
400
for lead
vanadates 6). Such processes may be made continuous, em-
ploying fused silica apparatus.
FIGURE
.
VITRE-
OUS SILICARDAC-
TION
CHAMBERND
CONDENSER
FOR
CONTINUOUS o r n -
TIRCURREINT
CHLO-
RIDIZATION
It
may be advantageous in
chloridizing operations to intro-
duce the chlorine through a small
fused silica tube directly into the
boat containing the charge in a
larger tube of vitreous silica 3) .
Electrically heated vitreous silica
retorts are suitable for preparing
beryllium chloride from beryl and
carbon in
a
stream of carbon tetra-
chloride and
chlorine at 800
C.
(7B). Phosgene undergoes exten-
sive decomposition at tempera-
tures above 300' (18) and is also
decomposed in radiation of wave
length 2750-3050 b. On the
other hand, it may be formed by
the photochemical union of its
elements
(36).
In producing anhydrous alumi-
num chloride from either alumi-
num oxide
or
metallic aluminum
and chlorine gas, the apparatus
must be capable of withstanding
chlorine at 1000 C. Intimate
contact of the reacting materials
is required for efficient results 41).
In preparing aluminum chloride, it
should be kept in mind tha t molten
aluminum readily attacks vit-
reous silica equipment. The lat-
ter has, however, been success-
fully used for purifying aluminum
chloride bv admixture with alumi-
num powder and resubliming 68).
Carl
11)
described in detail an electrically heated fused
silica rotary furnace for making anhydrous aluminum chlo-
ride, and Wohlers (73) applied similar equipment to the
production of anhydrous metallic chlorides in general (Figure
5 ) . Baughman 6) used
a
rotating fused silica cylinder,
13
inches
(33
cm.) in diameter,
60
inches
(152
cm.) long, heated
by an electrical resistance coil, in the chloride volatilization
of Black Butte ores and in separating the mixed oxides by
volatilization. Baskerville
3)
recommended vitreous silica
tubing for chloridizing thorium oxide mixed with carbon.
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~ CHLaRINATidN
,147
used silica equipment
is
very suitable for
u88
as con-
densers or mbliming chamber8 in chloridizing operatiom
where sudden cooling under severe cbemical conditions is re-
quired. Such condenser chambers, like the chloridizenr, may
be provided with eeveral independent electrical windings
for murate temperature control
(60).
Maier 61) specised
a
vitrabu. silica reaction chamber
and
condenser for the
continuous
countercurrent chloridisa-
tion of ores. As Figme 6 shows, the temperature conditions
here
are
unusually wvere, the pteheating and chlorination
mes
being maintained at about 900' C by electrioal re-
siatom
while water cooling isemployed at the lower end of both
mwtion
chamher
and condenser. The d u e n t gsses may con-
tain hydrochloric acid and water vapor.
Richsrdson (SO) claimed that s h u n assist materially in
chloridizing metals or metallic compounds, and recommended
a
tubular
silica
furnaoe maintainedat
3GtMooOo
C. for prc-
duaing
anhydrous
chlorides. In chloridbing operations a
mixture
of gwous hydrogen chloride and steam (70)wae
recommendedfor tr e ti ngoxide o m
aontsiningsmall
amounta
of
nickel
and
large
amounta of iron, and amixtureof hydrogen
chloride gas and chlorine may be employed
(17)
in refining
mixtures
of the platinum group metals. Chlorides may
also
be formed by renetion between the oxide and a mixture of
hydrogen chloride
gas, hydrogen,
and
steam; a
rotmy siliaa
tube furnaca is conveniently employed
(86).
Carrying chloridixing resctions further, metallic chlorides
tre ted
with hydrogen and
steam
at
a
high temperature are
in aome
c a w
converted into the
corresponding
oxides and
hydrogen chloride 86). Hydrogen chloride is also a frequent
by-product of inorganic chloridiaing
processes (69)
and may
besepsratedfromthemixedgasesandrecoveredforre-use
70).
Phosgene (26) escta readily with most metallic oxides to
giw
the chloride of the metal and carbon dioxide. Resistance-
wire-wound
fused
silica tubes are a convenient form of re-
actor. Bsskerville 4) e m p h w i d the simplicity of the prc-
oedure-merely heating the pulverised
material
in
a silica
tube
in
a stream
of
&aseous
phmgene. Hulett
(33)
mployed
this
reaction or purifying inorganic
m a t e d
contsiningiron,
including silica ssnd intended for optical
glass
manufacture.
Metallic anhides treated with phosgene give the ohloride of
the metal and carbon oxysulfide (36). By hydrolpi8 p h w
gene yields hydrogen chloride and carbon dioxide.
The preparation of very pure metallic chlorides often
in-
volves ae a 6nal step the fusion or dehydration of the d t n
a
current of hydrogen chloride, the material being contained
in a vitreous &ca boat inside a heated tube of the same ma-
t ri l
(60).
Photoehemioal A p p l i ~ a t i o ~
Actinic light
has
long been employed to promote chlorina-
tion processes.
It
ha
been claimed that under t he influence
of
ultraviolet light
a
molecular
rearrangement
d t a
uring
the
ohlorination of hydrocarbons, very liMe hydrogen
do
rids
being
liberated (67). Payne and Montgomery (66)
demiba a procam involving the expoeure of gaseous hydro-
oarbons
to
ultraviolet light after treatment with chlorine in
amtact with
a
catalyst formed by the chlorination of
a
liquid
hydmcarbon.
In
chlorinating rubber, ultraviolet rays may
be
used
in preparing the ubber solution in order to increasa
ita cancenhtion,
to
p m o t a halogemtion, and
to
s t a b
the f i ni shed product (13,84). Ultraviolet rays are also
olsimed
to
he valuable in promoting
the reaction
of chlo-
rinatedhydroosrbons with
sulfur
dioxide and chlorine for tho
production of organic haIogen4onic acid chlorides (38).
The exact reqnirementa in
this
field
are
not definitely
known, and
it
has
been
suggested
that
various parta of the
ultraviolet range below
3132
A
may
have
specifio
action
re-
sulting in ditrerent products from the same raw materiala
86). Where light of extremely
short
wave length
s
required,
the low-pressure mercury vapor lamp
in
quarts (operating
mostly in the
2536
A. region) may er advantagen in same
c ~ s e 8 n account of
ita
low temperature. On
the
other hand,
the heat contributed by the high-pressure quartz mewury-
vapor lamp may in some instance be advantageous in pro-
moting
an
endothermic reaction
68).
While glass equipment
is
photOchemicaUy suitable for
chlorinations employing tho longer rays
of
the ultraviolet
spectrum,
used quarts is
necessary as an
apparatus
material
whem the full actinic power of quarts mercury-vapor l a m p is
desired. In d d e quipment tubular
reaction
ahamhem
of nontransparent f d ilica may have inteersuJr fused-in
sectionsof transparent quarts glass where required for ultra-
violet irradiation. Large -ade equipment may be provided
with quarts
glass
details for internal irradiation and reaction
v d f other materials may be fitted with windows of
quarts glass in suitable packing glands.
The least expensive type of quartz glass apparatus for
carrsing out photochemical
chlorinations s
an arrangement
of Btrsight quartz tu& through which the gam or liquids
paes
while expoeed
to
the actinic light
source.
A coil
of
quarts glass tubing surrounding the ultraviolet light is more
&cient.
Various
forms of quartz glsss equipmenthave
been
deviaed
for bringing reacting m a t e d into
intimate
contact with
the actinic rays in continuous photochemical chlorinations in
the liquid or vapor phase. Typical arrmgement.9 of thiskind
are
shown in
Various patents
(7,30,40,47,74).
Literature Cited
(1)
An-,
E. E..
r.
(to B.
A.
8. Co.). U. 8. Patent
1,631,474 Nov.
(2) Avrea. E.E.. Jr.
(to
Shamlea 8olvents Co.).IM ,836,201
10,
1931).
. . .
(Deo. 8,
1931).
(3)
Btwkerville.C., . Am.C h . oc.. 28,92242
(ISM).
(4)B.skemiUe. C., eianca. 50,
443
(1919).
(6)
Bsulrhman.
W..
TmM.
Am.
Ek em.
Scc..
43,
281-316
.
(lG23).
Barter. J. P. (to
Imperial Chemioal Industden, Ltd.). U.
8.
Britton. E.
C..
Coleman.0 .H.. nd Hadler. B. C.. U. 8. Patent
Patent
2,047,611
(July
14, 1986).
>an,G. H., nd Zemba, J. W.
C h e m i d Co.). Ibid.. 2,084,937
June
22,1937).
Brook. B.
T.,
nd Pndmtt, F. W.. U. 8. Patent
(March 21. l917L
,
C&&,
C.,'Ma.~ rc ?mMioirr 9, 1139 (July 16,1
.Carl.
B.E., U.8. Patent 1,862,298
June
7. 1932).
Carter.
C.B.. and Coxe. A.E.,IW..
,572,613
Feb
9
chcrmiaohe
Fabrik BuOLSu. Frenoh Patent
788.167
(to
Don
1,320,831
LW .
1
1926).
(Aur.
1.
1934).
Patent 2,174.737 Oot. 3, 1939).
1,4aa&38 Juk 18.1922).
Ibid.,
2,156,039
April
ab. 1939).
Fnmch Patent
841.W
(May
18,1939).
C o w , G. H.. andMoore. GI.V.
to
DonChemicalCo.).U. .
h e .
.
O.,
Jr. (to Carbide
&
Carbon
chemi& Co.).Ibid.,
Daohlsuar,
IC.,
end
89hnitalsr.
E.
(to
I.
0 .
Farbrmindlutrie).
Deutwhe Gold-
und
8ililbemcJcheidesmtalt VORD. Rneedler,
Dyson, Q. M.,
C h .
n 4, G343 (1927).
Ed . Gu~tav,Sohand, R. E.,
end Lowry, C.
D., Jr.. Ibid..
8, 1-80 (1931).
IW.
0,346411 1937).
(ZO) E S,
Quatav, W h n ,
E.,HUUS.
0.. Van A d 4
P. M..
(21)
EUio, C.
(to Cbsdsloid Chemical
Co.), U.
8. Patent 1,aOZprO
(22) Enpa,W.. nd Redmond,
A. (to
Shell Development
Co.).
IW
(28) Fink, C.
0.. e
Marehi. V. 8.. Tmtu Ebdmrbn. &e., 74
(Oot.
24, 1916).
2,077,882 ApdI20, 1937).
(lueprint) (1W).
1917).
(24) Flaresoo, W.. Frenoh Pstsnt 788,632
Aug.
10,1934).
(ab)
Gibbs. H.D.
(to ssldsn Co,).
Brit. Patent
123,341
(Oat.
2
(26)Gibb.. W.
E., Rept. Tin and
Tungaten B o d
(Brit.),
1922.
8/10/2019 Enamel for Chlorination Process
6/6
148
I N D U S T R I A L A N D E N G I N E E R I N G
C H E M I S T R Y vol. 33,NO. a
(27)
Great
Western
Electroohemiad Co.. Brit. Patent 609.368
(28) Gro-a, P.
H.,
Unit
Pmeessas
in
Or-c
Byntheaia". andd.
(July 14, 1939).
1938.
h l l . E.
P.. and Heme,G..ID. ENQ.Carnu.. 31,1684-7 (1939).
Hart.
C..
U.
8.
Patent 2,030,867 (Feb. 18.1936).
Ibid., 2.030.868
(Feb. 18,
1038).
Bolt.
L.
C.. and
Daudt.
E. W.
(to
E.
I.
du Pont de Nemoun
6.
Co.. ho. ) . lb id . . 2.091.986 ( b t .
.
1937).
Hi&. G.'A.. U.8.'Pat&t 1;3&,38e
we b .
16. 1921).
1.
G. Farbenindukie,Brit. Patent 283.106 (Dea. 6,1928).
I n g e h ,
H.
J..
J .
Chem. 800.. 1927.2244-64.
Jackmu.
K.
.,J .
C h .
ducation.
10,622-6 (1838).
J a b . .
8..
Waioaripht. 0 E.. and
Hail-.
E.R.
(to Im-
wrid chermiod
Indun&.
Ltd.).
Brit. Psterk
438,Wk
(Oot.
?.
1936).
(38)
Johnmn,
G. W.
(to I.
0 FarbenindustriB).
IW..
616,214 (July
z 1.a3'1.662 (A U~ .1,1917).
Elipstein,E.
E.,
C h . Mark , 25.6936 1029).
Kmw %oh,
and
R6b, K. (to
Hohverkohlwm
Kgelgen
F. von, and w d , 0 .
0
(to VirSinia
bid.,
1.147.83a (J* 27,1916).
Lacy. B.
8..U. .
Patent 1,242,208 (Oot.9.1917).
L w .
B. 8. (to
Roesaler &
Edsoher
Chemical
i.iii,84a (&pt. ag. 1914).
Ibid.,
1,263,wW (April 23,1918).
U.
8.Patent 1,664,821 (Jan.3.1928).
,
F..
U. 8.
Pateut 1,459,777
r-hdmtrie)
Lsb.
Co.).
CO.),
Ibid..
(June
26.
1933).
(48) loyd,~~. J.,
and
Kennedy,
A. M., IW., 1,849,844 (March 16,
1932).
2
m h .
1. 18Ml).
(40)
Low. F.
8.
(&
Wedtvaco
Chlorine Fmducta
Co.),
Ibid.,
1,746,-
-- .- -_..__
(4) Maim. C.
G.,U. 8. Bur. Mined.
T d . aper 360
1826).
(61)
Maier.
C. G..
U.
8.Patent 2,183,987
(Oot.
as. 1938).
(62)
Msier, C.
G.
(to
Glad Weatem Eleotroohemioal
Ca.), Ibid..
2.14a.e~J-.
a
1 ~ 9 ) .
(63)
Moffett,
E. W., Winkelmann,
H . A.
and Willisma.
F. E. (to
(64)
Padrovmi,
C.. D e Bartholomasis, E., snd 8inirsmed. C., Ani
(66)
Palmer. W. . . and
Clark.
R. E. D..
ploe. Rar. 800.
(London).
~ a r b o u OW.).IW ,138,ma (Deo. 6, i9as).
X cam.
dem
Aim.,
41,6143 (1939).
. .
..
Al49,'3& (1984).
.
(Id.)]. U. 8. Patent 1,463,766 (May
I .
192.3).
2,Oa6,917
(March
31, 1936).
66)
Payne.
E. E.,
and Montgomery,
8.
A.
[to
Standard Oil
Co.
(67l
Prshl. W.,
and Mathen, W.
(to
F.
Raaohig.
Q.m.b.H.),
W
68) Ralaton, 0. C.. U. 8. Bur. Mines,
T d .
apa 321 (1923).
(69)
Raalin
Corp.,
Brit. Patent 489,964 (Aug. 6 . 1938).
(60)
Riohsrdmn,
H.
A.,
Ibid..
621,976
(June 6 .
1940).
631) Rob. K. (to EohverLohI-Indwtriatrie Akt. .).
IW..
14, 1921).
Patent 1,383,366
(Dee.
14. 1920).
68) Bsunders, H . F., and Butherland. L. T.
(to
Glyain Corn.).
U. .
(64)
8 o a Y t 6
Sen&& m6tallur(pque de
Eobokeu,
Brit.
Patent 47.124
I1.321pI
(66)8ooi66
intemationds
des
industried
ohimiques
et d6riv&a,
8.
A.
Holding. h o b
atent 834,124 (Nov. 14, 1938).
(66) &ell,
J.,
and Runkel, C (to I. Q. Farbenindustrie),
U.
8
Patent 1.880.167 (Nov. 28,1932).
(67) Teichmaoo. C. F.. Klein, H., and Rathemsaher.
0.
P.. U.8.
Patent 2,016,044 (8ept. 17. 1936).
(68)
Thomaa.C.A.. Scienoeof
Petmleum",Vbl.4.pp.a7862801.Ox-
ford univ. Praaa. 1938.
69) W-uht, R..
C h . &.
1923.121-2.
(70) Wesoott. E. W., U. 8. Patent 2,036,684 CApd 7, 1936).
(71)
Wiwevich.
P.
J.,
and
Vederdel. H. Q., C h . ea..
19, 101-17
and
Yntema,
L. F.. Tram. Am. I .
EQUIPMENT
M.
A. KNIGHT, J R ~
Maurice
A. Knight,h hio
TRICTLY
speaking, chlorination involves
the
substi-
tution of chlorine atoms for other atoms in molwules of
S
substance.
In
a
broader
sema
it
may
be
conaidered
ea
any pmoeas or chemical
d o n
nvolving chlorine itself
or one of ita compounds in whioh substitution or addition
of chlorine atoms occura. The aotivity of chlorine with nearly
every metal in the presence of water, the temperatures
reached
in
some meas, the organic solvent nature of many
of the compounds p r o d , and the frequent praeenoe of
hydrochloric acid rule out all forms of equipment except
ceramicwareor
glm.
Definition
of
Chemical Stoneware
Bow
is chemicsl
stoneware Mer en t from pottery,
porce-
lab, clay
building tile,
or
m e r pipe since they are
all
made
from day?' Brielly, the above forms are essentially alumi-
num silicates plus minor amounts of other materials. Chins
and
poroelain
are white, dense, often translucent ceramic
bcdies
that
are
fuUy
vitrified and
acidpmf.
Highly
p u m
raw
m~terials
re
used
to
en unr
whiteness, and the body
s
highly fluxed to
obtain
maximum denaity. This last ohar-
aoteristio pub definite Dse
limitations on
true
porcelain
articles. Pottery such as flower v ~ se s nd mme d i m a r e
is
not alwap v i W and depends
on
an applied glase
for
service. Elementa added for coloring and for manufacturing
eaee would lesoh out in acid Service.
Mechanical
strength
is
comparatively low.
Building
brick and sewer tile generally
take raw clay from local
murcea,
and
it
is formed
m d
i red
without puriscation
to mske
a earviceable prcduot.
The
premnce of
iron permits lower firing
t emperah snd im-
parts the familiar red color. The raw clays are too impure
to be used for other
ceramic
purposes. Chemical stoneware,
in addition to
being
acidpmof, must meet phyeical requh-
menta ea to stmngth,
tempersture,'pamsify,
snd dimen-
Dona
in
a variety
of
&apes which am much
larger than
