EIR-TM-HL-235.txt

C;%é\é{\\»cie~

= | l—' Technische Mitteilung TM-HL-235
Abte"ung: HL Bearbeiter: A . Dfindal" * /Skh Visum: j m
Betrifft: Datum: 20.8.74
" Synthesis and Gas Chromatography of Selected
Metal Chlorides. 45 Seiten
Zeichnungen
Contents
page
1. Synthesis of Molybdenum Chlorides 2
1.1. Aim of Work 2
1.2. Introduction 2
1.3. Experimental 5
1.4 Results and Discussion 8
2. Gas Chromatography of Volatile Metal Chlorides
at High Temperature 11
2.1, Aim of Work 11
2.2. Introduction 3.1
2.3. Experimental 20
2.4, Conclusions 27
5. References 29
* Privab: Arif Diindar, Anittepe, Ata Sokak 2-4
ANKARA - Turkey
* Univ.: Middle East Technical University,
ANKARA - Turkey
Verteiier| Abteltung | Name Expl. | Abteilung Name Expl.
GL Direktion 3 DO |Bibliothek 3
HL |Dr. J. Peter 1 Beserye 15
alle Gruppenleiter je 1
A. Dindar 2
W. Eberhard 1
Dr. M. Furrer 1
Frau Dr. Ianovici 1
Dr. K. Tunaboylu 1
CH R. Keil 1
ME G. Ullrich 3

-Dieses Dokument ist Eigentum des Eidg. Institutes fir Reaktorforschung-

TM=HL=235

page 2
1. Synthesis of Molybdenum Chlorides
1.1. Aim of Work
In the project of a Molten Salt Fast Breeder Reactor(l) the

chloride of plutonium-239 (15%) diluted by sodium chloride is
the molten fuel. Molten fertile material is UC1l_-238 (65%) plus

3

sodium chloride besides newly bred PuCl, and fission products

which acts also as blanket material andsas coolant. Molybdenum
is one of the fission products and forms low volatile chlorides
with chlorides present. It is also one of the most important
construction materials and will probably be used in this type

of reactor.

Therefore, our aim was to synthesize molybdenum (V,ITII,II)
chloride-samples which could be used in the experiments for

the project.

1.2. Introduction

Experiments were done to synthesize molybdenum penta- and tri-

chlorides.

—— — —— — — — ———————————— — — ————— —————— ————————— —

The method used was the reaction of molybdenum(VI)oxide with

boiling hexachloropropene.

MoO_, + 3 C

3 Cl6 + MoCl_. + 3 C

5 CluO + 1/2 C1

2

2 3

Porterfield and Tyree, Jr(z) showed that the method used by
Herman and Suttle for the preparation of uranium(IV)chloride(B)

from uranium(IV)oxide and hexachloropropene can be conveniently

extended to other polyvalent metal chlorides.
TM-HL-235
page 3

M2On + nCSCl6 +* 2 MCln + nCBCluO
They added: "These chlorides are well characterized and have
long been prepared by satisfactory means. However, the method
described has the advantages of greater convenience and
rapidity, indifference to small amounts of water on the oxides
(the water is converted to hydrogenchloride and trichloro-
acrylic acid)

03016 + 2 H20 - 0301302H + 3 HC1
relatively complete conversion of the oxide to the chloride,

and products which are easy to separate and purify."

Two methods were used for the synthesis of molybdenum trichloride.

1.2.2.1. Reduction of Molybdenum pentachloride with hydrogen:

This reduction is carried out by passing a current of pure and
dry hydrogen over molybdenum pentachloride.

MoCl5 + H2 > MoCl3 + 2HC1
The purification of hydrogen is very important, because the
formation of oxychloride must be avoided. It is also necessary
to Keep the reaction temperature under 194°C in order to avoid
the formation of a cake in the molybdenum pentachloride mass
(see table 1).
TM-HL-235
page U4

ASubstance mp , °c color
MoCl5 194 black
MoClu 317 brown
MoCl3 1027 dark red
MoCl2 decomp. yellow
MoOCl3 green
MoOClu green

Table 1 Physical properties of molybdenum chlorides

(4)

and oxychlorides

1.2.2.2. Reaction of Molybdenum(VI)oxide with Hexachloropropene

The analysis of molybdenum chloride which had been synthesized
by the method (1.2.1.) showed that the stoichiometric ratio of
chlorine to molybdenum was close to 3 (see 1.4.1.) that shows

another possibility.to synthesize molybdenum trichloride by the
same method but for a longer time as to complete the reduction.

(5)

Besides this Larson and Moore reported that in preparation of
molybdenum tetrachloride by the reaction of molybdenum penta-
chloride with refluxed chlorobenzene, substantial formation of
molybdenum trichloride occured after extended reflux periods
(greater than 10 hours). It is possible that hexachloropropene
can be used instead of chlorobenzene in excess, due to its resem-
blance also being unsaturated, and able to reduce molybdenum

pentachloride to -trichloride.
TM-HL-235
page 5

1.3. Experimental

200 ml of hexachloropropene (1.41 mole) and 20 g of molybdenum(VI)
oxide (0.14 mole) were put in a 250 ml round-bottomed flask with
a reflux condenser. The upper end of the condenser terminated in
a drying tube. The flask was filled with argon. The reaction
mixture was brought to the boiling temperature by means of a
heating mantle and refluxed for 15 minutes, until reaction was
complete shown by a color change from yellow to dark red. Argon
was continuously flushed through the system. The more slowly the
cooling process is performed, the larger is the size of the indi-
vidual crystals obtained. Therefore, the flask was well insulated
and allowed to cool to room temperature for 3 hours. The crystals
were very dark-colored under a dark red solution. The flask was
removed from the reflux condenser and closed immediately with

a sintered glass filter tube. The upper end of the tube terminated

in a round-bottomed flask in which the filtrate can be collected.

Then the whole system was inverted and the metal chloride was
separated from the solution by filtration. During this time, argon
was still in charge into the reaction flask. The filtering opera-
tion was completed slowly in about 3 hours. Before the filtration
was completed, the crystals were washed three times with previously
dried CClu which was added by opening the system when the crystals

were still covered by solution.

After the filtration process, the round-bottomed flasks at both

ends of the filter tube were replaced by dry argon filled flasks.
The molybdenum pentachloride crystals were then sucked and dried
under vacuum. Finally, the system was transported into the glove-

box and opened.
TM-HL-235
page 6

———————— —————— T ————— ———————————————————— -

1.3.2.1. Reduction of molybdenum pentachloride with hydrogen

The reaction vessel was made of quartz glass. It was equipped
with a porous glass try on which the molybdenum pentachloride

crystals were put.

After molybdenum pentachloride had been put inside the vessel,
in the glove-box, the vessel was placed in a vertical electri-
cal oven (Fig. 1). The vessel had a spiral tube in its lower
part so that the entering gas (hydrogen/argon 1l:1) was preheated
before coming into contact with molybdenum pentachloride. At its
upper end the vessel terminated in a drying tube. The leaving
gas was passed through water in order to absorb hydrochloric
acid to be determined afterwards. The vessel was insulated with
glass wool and the reaction was carried out at 167-175°C for

11 hours. The hydrogen and argon mixture was passed through the
molybdenum pentachloride mass in order to prevent back sucking
in a possible stop of the hydrogen current. During the reaction

the vessel was vibrated continuously to prevent cake formation.

1.3.2.2. Reaction of Molybdenum(VI)oxide with Hexachloropropene

90 ml of hexachloropropene (0.63 mole) and 6 g of molybdenum(VI)-
oxide (0.042 mole) were put in a 250 ml round-bottomed flask and

the same procedure as for the synthesis of molybdenum pentachlo-

ride was followed with the only exception that the mixture was

refluxed for 20 hours.
Pig. 1

vibrator

Reduction of MoCl

dryer

=

5 to MoCl3

water

TM-HL-235
page 7

thermoelement

temperature
controller

TM-HL-2 35
page 8

1.4, Results and Discussion

Molybdenum pentachloride produced by the method 1.3.1. was analy-
zed colorimetrically for molybdenum and by a potentiometric
method for chlorine ). It was found that the ratio in moles of
chlorine to molybdenum was 3.64 and the mass balance of molyb-

denum and chlorine gave 100.8 percent.

An analysis was also carried out for the chlorine content of molyb-

(6)

denum pentachloride samples by the gravimetric method . The

results are shown in table 2 (assuming the absence of impurities)

chlorine molybdenum Cl/Mo
no |sample weight |wt. g moles |wt. g | moles . .| in moles
1. ] 0.0766 g 10.0405 | 0.00114 | 0.0361 |0.00038 . 3,02
2 .. .4 0:X2TT & 0.0691 ] 0.00195 |0.0586 |0.00060 5.25
Table 2 Analysis of molybdenum pentachloride samples

From the results of these analyses, the sequence of the following
reactions seems reasonable and possible.

C Cl6 C Cl6

5 MoCl, 2 0. Moc1

MoO., + C Cl6 + MoCl

3 3 B 3

On the other hand, because the water content in our glove-box was
very high (39 ppm) the hydrolization and oxidation of molybdenum

pentachloride could cause deviations in the results.

*) Performed by R. Keil, EIR-CH
TM-HL-23%5
page 9

1.4.2.1. Reduction of Molybdenum Pentachloride with Hydrogen

This experiment was done two times with (a) the so called molyb-
denum pentachloride synthesized in 1.3.1. and (b) the commercial

molybdenum pentachloride.

The first one was abondoned afterwards because the results of
analysis of molybdenum pentachloride showed the stated composi-
tion M0013—4‘ Therefore, it was tried to reduce the commercial
molybdenum pentachloride to -trichloride. But during the prepa-
ration of the reaction vessel, high water content in the glove-
box (80 ppm) caused some amount of molybdenum pentachloride to
hydrolize and as a result of this hydrolization, the green

crystals of molybdenum oxychlorides were observed (see table 1).

The eluted HCl was titrated with sodium hydroxide after 11 hours

of reaction time. Table 3 shows the results.

N HC1 «|N HC1/N HC1
No | N NoOH | VHC1, ml |V NaOH, ml | N HC1l |.(expected) .|(expected) .
— e — -
1 0.20 25 10.86 0.0869] 0.4654 18.7 %
2 0.25 ho 16.19 0.1012] 0.4654 21..T ‘S

Table 3 Determination of the degree of reduction of MoCl_ to

5
MoClB.

* MoCl5 input

7 g (0.0256 mole)

HC1l expected 2 x 0.0256 = 0.0512 mole
water 110 ml

HCl1l expected: 0.0512 (1000/110) = 0.4654 N

However, it seems possible to us to perform this reaction under

anhydrous conditions.
TM-HL-235
page 10

1.4.2.2. Reaction of Molybdenum(VI)Oxide with Hexachloropropene

Molybdenum trichloride produced by this method was analyzed again
by the colorimetric method for molybdenum and by the potentio-
metric method for chlorine* and it was found that the chlorine:
molybdenum ratio, in moles, was 3.30 whereas the mass balance of

molybdenum plus chlorine gives 100 %.

A gravimetric analysis was as before, carried out for chlorine
content of our molybdenum trichloride. Table 4 shows the results

(assuming the absence of impurities).

sample chlorine molybdenum Cl/Mo
No |weight, g wt, g moles wt, g | moles in moles
1 0.2359 0.1284 0.00362 | 0.1075 | 0.00112 3.23
2 0.1887 0.1026 0.00289 } 0.0861 | 0.00090 dvel

Table 4 Analysis of molybdenum trichloride samples

From the mass balance of molybdenum and chlorine, which is 100 %,
it is clear that our product contains no impurity, ie oxides,
oxychlorides. In this case the molar ratio of chlorine to molyb-
denum makes us to think about the incomplete reduction of molyb-
denum pentachloride to -trichloride. In this case molybdenum
trichloride can be separated from the other by means of an appre-
ciable organic solvent in which only it is soluble (ie, alcohol,
ether).

* Performed by R. Keil, EIR-CH
TM-HL-235
page 11

2. Gas Chromatography of Volatile Metal Chlorides at High Temperature

2.1. Aim of Work

Our work is a part of the project of a Molten Salt Fast Breeder
Reactor. How are the volatile metal chlorides formed? As already
mentioned, the molten fuel, the molten fertile material, the
coolant and the blanket material contain chlorides. From the
fission products, germanium, arsenic, tin and antimony form vola-
tile chlorides while zinc, gallium, rubidium, zirconium, niobium,
molybdenum, cadmium, indium and cesium form low volatile chlo-

(7)

rides . Therefore it is possible to collect information about

the formation of these volatile metal chlorides by gas chromato-

graphy.

2.2. Introduction

Gas chromatography is a technique for separating volatile sub-
stances by percolating a gas stream over a stationary phase. It
is in analytical application widely. Its greatest advantages are
its speed, resolution, qualitative and quantitative analysis and

its very great sensitivity.

In general, gas chromatography has largely been concerned with the
separation of volatile organic compounds and not too much has been
done with metal chlorides. Three trends are apparent in the re-
sults reported so far. They involve the use of fused salts,
slightly volatile liquids and solid materials as the stationary
phase. Fused salts, while useful at very high temperatures, are
difficult to prepare on the support, especially in anhydrous form
and are subject to reaction with the solutes. The slightly volatile
liquids are lost from the column, redistribute on the support,

may be thermally unstable, and are capable of reactions with the

(8)

solutes
TM-HL~2 35
page 12

The main problem in the qualitative and quantitative application
of gas chromatography in determination of inorganic volatile
chlorides is the choice of an appropriate liquid phase which
does not react with these compounds. In general, reactivity may

(9)

be a question of

a) interaction between solute and the liquid phase (sometimes due
to the metallic tubing of the columns) resulting in the crea-

tion of interaction products
b) sorption of the solute on the solid support, or

¢) the way by which the solutes are dissolved in the liquid phase.

The reactivity of inorganic volatile chlorides with respect to

packing materials and occasionally the difficulty in determining
the magnitude of this effect has often led to different opinions
on the stability of various substances that might be used as |

packing materials for the separation of inorganic chlorides.

Conclusions regarding the reactivity may be drawn from (a) obser-
vation of the chromatograms obtained, (b) the possible changes
occuring in the packing material after the experiments, (¢) the
ratio of logarithms of specific retention volume to vapor pressure

of liquid phase.

The stability of the baseline and its deviation from zero, the
presence or absence of artefact peaks or the non-appearance of
expected peaks, the symmetry of the peaks looking for tailing and
skewing are the points to be examined so as to draw conclusions
regarding the reactivity. Possible retention of some of the solutes
in the column can be ascertained by checking whether there is any

difference . in the weight or color of the column packing material
TM-HL-2 35
page 13

before and after any series of experiments. Finally one can
obtain indications as to whether or not the solutes are ideally
dissolved in the liquid phase, without any change of their mole-
cular structure, by examining the plot of logarithm of specific
retention volume vs logarithm of vapor pressure which should be a

straight line with a slope equal to unity.

Since in analytical gas chromatography, mg or sub mg amounts of
sample are brought into contact with at least a thousand-fold
amount of column material, it is evident that when reactive sub-
stances are involved, the inertness of column materials has to
meet severe demands. When quantitative results are aimed at, the
use of metals and organic liquids except completely halogenated

products, and diatomaceous supports is not allowed.

The lack of inertness of metals such as copper and stainless

steel is perhaps best illustrated by the ready attack of these

by chlorinating agents. Further proof of the unsuitability of,

for example, copper is the violent reaction observed between it
and antimony (V) chloride, both in liquid and in gas phase.
Diatomaceous supports are unsuitable for the present purpose
because of their adsorptive properties. For example, large

amounts of HC1l are almost irreversibly adsorbed by Sil-O0-Cel

C 22 (chromosorb R or P). These supports also have the great ad-
sorption affinity for metal halides. Even the white diatomaceous
supports, which are usually regarded as being less adsorptive than
the red ones, are unsuitable, because of the numerous metallic
impurities which may react. It was proved that even rigorous

acid treatment failed to remove these impurities completely(lo).
Some of the chlorides, like SbCls, are active chlorinating agents,
or moreover, free chlorine may be present in the sample. The
stationary liquid should therefore be at least resistant to

chlorination. This condition is not met by most organic stationary
TM-HL-235
page 14

(10)

phases. Sie et al. reported that a considerable amount of
HC1 was formed when chlorine was contacted with silicone grease,

even at temperatures as low as room temperature.

(11)

Freiser has reported the separation of tetrachlorides of tin
and titanium at 102° by using n-hexadecane (31%) coated chromo-
sorb. Both tin(IV) and titanium(IV) chlorides gave well defined,
symmetrical bands. The ratio of vapor pressure of these two
compounds was about the same as the inverse ratio of their reten-
tion times, showing the absence of reactions with the stationary

phase.

ke ) by including

This study was extended by Keller and Freiser
niobium(V) and tantalum(V) chlorides and use of somewhat less

volatile stationary phases (n-octadecane and squalane) at tempera-
tures of 150 to 200°. Keller(s)

apiezon T and silicon o0il as stationary liquids on red chromo-

separately reported the use of

sorb as a support in copper columns at temperatures of 100 to

2007 . The separation of the four chlorides by these authors is
more of a qualitative nature. Studying the chromatograms shown by
Keller, it is concluded from the presence of shoulders,tails and
artefact peaks that decomposition of solutes have occurred to

a large extent within the column and both apiezon grease and sili-
con oil reacted with chlorides. Tin(IV)chloride on apiezon grease
and titanium(IV)chloride on silicon oil at 100° did not appear.
Keller concluded that the normal alkanes appear more satisfactory

than branched chain compounds.

Wachi(ls)

at 125o using a stainless steel column packed with silicon grease

was unable to elute tin(IV) and titanium(IV) chlorides

or apiezon M on ground Sil-0-Cel C 22 insulating brick. Failure

to obtain peaks was attributed to complete reaction of the chlorides
TM-HL-235
page 15

with the greases and the walls of the column. Wachi then turned
to fused inorganic eutectics in glass columns and reported the
5 and SnClu-Tlclu. Poor

results with the latter pair were attributed to the insolu-

separation of the pairs SnClu-SbCI

bility of titanium(IV)chloride in eutectics. Wachi also
reported the failure of nitrate eutectics to separate the tran-
sition metal chlorides due to the oxidizing properties of the
nitrates. He attempted the gas-solid chromatography of tin

and titanium tetrachlorides by using C-22 firebrick as stationa-

ry phase, but resolution was very poor.

(14) used a eutectic mixture of BiCl3 and PbCl2

on Sil-0-Cel C-22 firebrick for a separation of titanium(IV)

Juvet and Wachi

and antimony(V) chlorides at 240°. A pronounced baseline in-
stability was observed. Their work was not of quantitative

nature.

(15) reported interaction between the silicon products

Tadmor
and metal halides. He obtained well defined peaks attributable
to reaction products when analyzing germanium(IV), tin(IV) and

arsenic(III) chlorides with silicon grease as stationary phase.

(16)

In a later paper' ', Tadmor reported the separation of germa-
nium(IV), tin(IV) and arsenic(III) chlorides and their inter-
action on a column packed with Sil-0-Cel - C-22 insulating brick,
by an isotopic exchange technique (hydrochloric acid labeled
with Cl1-36). The chromatograms obtained with the uncoated support
showed irregular peaks and imperfect separations. The incomplete
recovery of the chlorides (65% for GeClu, 78% for AsClB) at the
column's outlet was attributed to losses due to hydrolysis
occurring within the column. Better separation was obtained by
coating the support with 1 percent nitrobenzene. The chromato-

grams shown exhibit peak shapes which are considerably distorted.
TM~-HL~-235
page 16

(17)

chloride and germanium(IV) chloride on 17 different stationary

Tadmor also studied the separation of arsenic(III)

liquids on Sil-0-Cel brick and reported the changes in weight
of these immobile phases as a function of temperature, and the
maximum temperatures at which no change in weight had been
detected. The chromatogram of germanium(V) and arsenic(III)
chlorides on uncoated Sil-0-Cel brick exhibits during 110 minu-
tes only one peak for them. The ratio of the retention times

of these chlorides is approximately the inverse of their vapor
pressure ratio at 100°. This indicates the absence of reaction

with support.

Wilke et al.(l8)

the tetrachlorides of silicon, tin and titanium by gas-liquid

reported the determination of the purity of

chromatography. They used nitrobenzene, silicon oil and apiezon
N as stationary phases at about 100° on diatomaceous firebrick
supports (sterchamol, diaphorit). They found that well resolved
individual peaks for silicon (IV) and titanium(IV) chlorides
could only be obtained by preinjecting a sufficient quantity

of titatium(IV) chloride. Although a complete separation is
reported with a column thus treated, the peaks still exhibit
considerable tailing, as is evident from the chromatograms
shown. No proof is given of complete recovery of solutes from

the column.

Dennison and Freund(lg)

reported the separation of arsenic(III),
tin(IV), germanium(IV) and titanium(IV) chlorides on halocarbon
6-00 coated (24.5% W/W) chromosorb W at 107° and 126°. They used
new all-glass apparatus with a specially developed sampling
chamber. Elutions were in the order of their boiling points.

They also tried quantitative determination of arsenic(III) and
tin(IV) chlorides. Maximum error was 6 percent which was believed
to result primarily from the premature vaporization of the sam-

ples as they were being injected.
TM-HL-235
page 17

(20)

Brazhnikov and Sakodynski reported certain regularities in
the retention of chlorine-containing inorganic and organometallic
compounds. They separated germanium(IV), silicon(IV), tin(IV) and
titanium(IV) chlorides on the solid support polychrom, a type of
teflon, which was coated with siloxane elastomer E-301, apiezon N,
n-octadecane, polyorganosiloxane liquid VKZh-94, liquid polytri-
fluoromonochloroethylene of the Kel F-10 type, Kel F-3 or AlBrS.
From the chromatograms shown, the results are of only qualitative

nature.

(21)

transition metal chlorides including arsenic(III), tin(IV), anti-

Zado and Juvet reported the elution characteristics of 11

mony (III), molybdenum(V), niobium(V), zirconium(IV) chlorides on
12 inorganic fused salt mixtures, by using acid-washed chromosorb
P, porous vycor, glass beads as solid support. They discussed that
most of the solutes studied are capable of forming chloro-complexes
with available chloride in the liquid phase melt, and the ratio of
the dissociation pressures of two chlorocomplexes is, in general
different from the relative volatility ratio of the uncomplexed
solutes and finally concluded that the separation of solutes based
on this difference in complex stability would be particularly
desirable for situations in which solutes have similar boiling

points.

(10) studied 19 substances including germanium(IV),

Sie et al.
arsenic(III), tin(IV), antimony(III, V), gallium(III) chlorides

on Kel F-40 as stationary phase which was coated (15% W/W) on
haloport F as solid support. Except for the unstable tetra-
chloride of vanadium and pentachloride of antimony, all inorganic
chlorides examined have been found sufficiently stable to permit
a.gas chromatographic separation. Besides small peaks attributable

to HCl, no artefact peaks were observed at all. With proper choice
TM~-HL~-235
page 18

of column materials and some adaption of apparatus and injection
technique to the reactivity of these compounds, quantitative
analyses are possible with an accuracy equal to that normally

obtained in gas-liquid chromatography.

(22)

Stumpp reported that graphite was a suitable stationary phase
for separating metal chlorides by the technique of gas-solid
chromatography. A special construction permitted the injection of
the solid metal chlorides. The chromatograms obtained exhibit
tailing to a large extent and are far from being of quantitative

nature.

(9)

Parissakis et al. investigated the interaction of some chlorides
including tin(IV), germanium(IV), arsenic(III), antimony(V) chlori-
des upon the stationary phases Kel F-10, Kel F wax, silicon oil
DC-550, silicon rubber, apiezon L, phasepack P and graphite. They
reported that with the exception of antimony (V) and vanadium(IV)
chlorides, the chlorides tested had shown no interaction with the
above mentioned phases. Kel F wax on celite gave the most symme-
trical peaks with negligible tailing. Titanium(IV) chloride

caused darkening of apiezon L.

(23)

In another paper , Parissakis et al. also demonstrated the
appropriate operation conditions for good qualitative and quanti-
tative separation of mixtures of five inorganic volatile chlorides

on the same stationary phases mentioned in the previous paragraph.

By gas chromatography, it is also possible to calculate some physico-

chemical properties, ie heat of solution
TM-HL-235
page 19

For any given solute, the retention values are related to the

column temperature by the following relationship(eu).
. J Fc(tR-tA) 273
& W, Te
where Vg = specific retention volume
J = pressure drop correction factor
Fec = volumetric flow rate of the carrier gas measured
at the outlet pressure and column temperature
trR = retention time of substance
tp = retention time of air

tRl = t'R - tA
Wr, = weight of liquid phase

Tc = column temperature, %

Through the experiments and temperatures, it can be assumed without
any serious error that J and Wy, remain constant. On the other

hand, correction for the gas flow rate is

Te

Fc=Fmi,a-

where Fm and Td are the flow rate observed and the detector tem-
perature, respectively. Substituting into the main equation
gives
Vg = IFB g0 273 | gop o
wl "R T4 R
where K is the new constant term defining (JFm 273/W1l Td).
Taking logarithms

InVg = LnK + Lntg'
™-HL,~235

page 20

(25)

As known

Vg & = === 4+

where AHs is the heat of solution of the substance in the liquid

phase. Equating the last two equations

Ln tg' = - === + C!

where C' is equal to (C-Lnk)

Rearranging
AHs
Log tR' = - + C"
2.303 RT

The heat of solution may be determined directly from the slope
of the straight line which will be obtained by plotting log tg'

vs reciprocal of the column temperature.

2.3. Experimental

The chromatograph used was a VARIAN 2100 equipped with a Ni-63
electron capture detector. Nitrogen was used as carrier gas at
flow rates of 24-48 ml per minute. The flow rates were measured
by the soap bubble method. The pressure regulator was used to
assure a uniform pressure to the column inlet and thereby a con-

stant rate of gas flow.
TM-HL-235
page 21

Columns used were U-shaped glass tubes (to avoid reactions of
the highly corrosive chlorides) 2 mm ID, 1/4 inch OD, 170-180 cm
long.

The recorder was A-25 VARIAN with different suitable chart speeds

and mV ranges.

All columns were packed, under anhydrous conditions when neces-
sary, by adding the packing material to the column by tapping

the side of the tube gently with a spatula until the column
packing material did not settle any further. In the case of gas-
liquid chromatography with n-hexadecane as the stationary phase
and carbopack A as the solid support, 16 g of carbopack A was
suspended in a solution of 2 g of n-hexadecane in 10 ml of toluene.

The solvent was removed on the water bath under vigorous stirring
(26)

The columns were conditioned each time overnight (or 48 hours in
the case of carbopack B) at the maximum recommended temperature.
The effluent end of the column was not connected to the detector

during the conditioning period.

Column oven temperatures varied depending on the packing material
and the elution characteristics of the substances. In the injec-
tions, the temperature of the injection port was 30-50o higher
than that of the column oven. The detector temperature was either

50o higher than that of the column oven or constant at 3000.

The elution characteristics of the volatile metal chlorides,
arsenic(III), titanium(IV), tin(IV) and antimony(V) chlorides
were studied. They were obtained from commercial sources. As it
is known they are highly corrosive, volatile and very easily
hydrolized to insoluble hydroxides and basic salts even in the
presence of traces of moisture. To avoid this, the samples were
prepared under nitrogen atmosphere in the glove-box and stored

in glass-stoppered flasks.
TM-HL-235
page 22

Because of the very high sensitivity of the detector even for the
smallest amounts of pure chlorides (for CCly, it is 19 - g
our chlorides were introduced as their solutions in n-hexane.

The metal chlorides used had satisfactory solubilities in n-hexane.

The samples were introduced by means of Hamilton 701 or S.E.G.

lo A-FN-GP syringes.

Repetitive retention measurements were made for each solute at

each temperature.

Packing materials:

. SE-30 (methyl silicon), 3% W/W on varaport 30, 100/200 mesh
Carbopack A

Carbopack A, hydrogen treated

. n-hexadecane, 12.5% W/W on carbopack A

Ui & W -
L .

. Carbopack B, hydrogen treated (commercially)

Besides the metal chlorides, air, chlorine, hydrochloric acid and
some hydrocarbon injections were carried out independently to
compare them with the metal chloride chromatograms under the same

conditions.

For each of the metal chlorides, three solutions with different

concentrations were prepared.

AsCly: 1. 2.84 x 107° g/ml SnCl,: 1. 2.94 x 107° g/ml
2. 3.74 x 107" g/ml 3, 3.86 £ 1077 g/ml

3. 0.97 x 10 ° g/ml 3. 1.00 x 10°° g/ml

TiCl,: 1. 2.28 x 1072 g/ml sbCl; 1. 3.10 x 1072 g/ml
3.00 x 107" g/ml 2. 4.08 x 107" g/ml

0.78 x 10°° g/ml 3. 1.06 x 10™° g/ml
TM-HL-235
page 23

The packing material used first was SE-30 as the stationary phase
on varaport as the solid support. This column had already been in

use at the beginning of the present work.

The retention time of air in this column was determined as 0.40
min. n-Hexane exhibited many unexpected peaks (Fig. 2). As shown
having nearly the same area, two big peaks do not permit us to
think about any impurity in the sample as the reason. The peaks
show considerable tailing. The reaction of n-hexane with the
packing material is probably the reason for these findings. Since
no oxysorb was being used at that time, the impurities in the

carrier gas might cause the small peaks to appear.

Free chlorine and hydrochloric acid gases can play an important
role in the molten salts reactions which take place in the reactor.
This is the reason for examining them besides the metal chlorides
as solutions in n-hexane. When chlorine was injected, three shoul-
ders, one of which was Cl2, were obtained on the first peak of
n-hexane (Fig. 3). The other shoulders may be attributed to
possible reaction products. With HCl, no special peak resulted.

It is quite possible that HC1l is hidden in one of the n-hexane
peaks. When chlorine and HCl were injected as gases, they exhi-

bited many peaks, showing interaction inside the column (Fig. 4).

Arsenic(III) chloride solution was injected at temperature inter-
vals from 90O to 200°. Two peaks besides those for n-hexane were
obtained at 125, 130, 150, 175 and 200°. Figures 5-8 represents
small peaks, shoulders and tailing to a large extent. However,
the second peak disappeared at lower temperatures (90, 100, 1100)
(Fig. 9-11). This could be explained in two ways, (a) since these
temperatures are lower than the boiling point of arsenic(III)
chloride (1300) it might be retained inside the column, (b) as

a result of repetitive injections, the solution might oxidize

and hydrolize completely and arsenic trichloride might disappear.
as a result of both, the first peak is attributed to the reaction

product.
TM-HL-235

page 24
¢, 9K 1/Te trs min tp-tp=tg', min Log tgr'
398 0.00251 11,30 10.90 1.04
403 0.00248 9«33 8.93 0.95
423 0.00236 4.45 .05 0.61
Lu8 0.00223 2.+20 1.80 0.26
h73 0.00211 Y2 0.85 -0.09

The logarithm of adjusted retention time was plotted vs. the
reciprocal of absolute column temperature for arsenic trichlo-

ride (Fig. 12). The slope of the straight line is 2815. Then

AHs = -(2815)(2.303)(1.987)

The heat of solution of arsenic(III) chloride in methyl silicon

is -12.8 kecal per mol.

When the most diluted solution of titanium tetrachloride was in-
jected (0.78 x 10-8 g) at 130, 150, 175 and 2000, one big and
two small peaks were obtained (Fig. 13). The retention time of
the biggest peak is identical to the unexpected peak of the ar-
senic(III) chloride chromatogram. When the more concentrated so-
78) at

the same temperatures as above, too many peaks resulted, showing

lution of titanium(IV) chloride was injected (3.00 x 10

the interactions inside the column with increasing concentration

of chlorine (Fig. 14).
TM-HL-2 35

page 25

When tin(IV) chloride was injected at 200 and 2250, a shoulder
on the first peak of n-hexane was obtained with a retention time
equal to those of the unexpected peaks of arsenic(III) and ti-
tanium(IV) chloride chromatograms. Two more peaks resulted, the

second one probably being the tin tetrachloride peak (Fig. 15).

The case with antimony (V) chloride is similar to titanium(IV)
chloride. When the least concentrated solution of antimony penta-
chloride was injected (1.06 x 1078 g) at 130 and 150°, a big

peak with a retention time again equal to those of the unexpected
peaks were obtained (Fig. 16). When the more concentrated solution
of antimony pentachloride was injected (4.08 x 1077 g) including
the temperatures 100 and 115O too many peaks were obtained (Fig. 17).

After the failure to determine and separate the metal chlorides
with this column we turned to gas-solid chromatography and used

carbopack A as the solid packing material.

When n-hexane was injected into this column a lot of unexpected
peaks, also including a negative peak, were obtained (Fig. 18).
HC1l in gas form gave only one peak with considerable tailing.
However, repetitive injections created new extra peaks. With chlo-
rine injection in gas form four peaks resulted. Tin tetrachloride

(1.0 x 1078 g) gave a small peak (Fig. 19).

The column created two peaks itself when the baseline was drawn
without any injection, by programmed temperature method (Fig. 20a).
The number of the peaks was five when n-hexane was chromato-
graphed by the same method (Fig. 20b). Then many organic solvents
namely cyclohexane, heptane, iso-octane, toluol, benzol and

decane were tested by both programmed temperature and constant
temperature methods. But none of them exhibited chromatograms bet-
ter than those of n-hexane. n-Hexanes from different commercial

sources were also tried and with that from FLUKA three peaks
TM-HL-2 35
page 26

including the negative one were eliminated (Fig. 21). With injec-
tion of chlorine and HCl separately in n-hexane, many peaks were

obtained. At 60°, HC1l and chlorine have the same retention time.

(27) reported that the use of gas-solid

Di Corcia and Bruner
chromatography was extended to the elution of polar compounds
by treating graphon, MT and FT with hydrogen at 1000°. "In com-
paring the adsorption isotherms before and after treatment, it
appears,that chemisorbed oxygen, always present in these adsor-
bents, is removed. Peak tailing is eliminated or strongly redu-

ced."

Upon this, we treated carbopack A with hydrogen at 800°C for
seven hours (we couldn't manage to reach 10000). After this
treatment, we still couldn't eliminate the extra peaks for

n-hexane, the number being 2 this time.

Then we again turned to gas-liquid chromatography and used n-
nexadecane coated on carbopack A. We injected different organic
solvents into this column and obtained only one peak at 40° for
all of them, that of n-hexane being the most ideal one. The nega-
tive dip after this peak was attributed to detector contamination
(Fleg: 22).

When chlorine and HCl were injected separately in gas form, they
gave only one peak with tailing to a large extent (Fig. 23, 24).
Arsenic(III) chloride did not appear at 100° and the baseline
exhibited pronounced instability. That was attributed to the
column bleeding at this temperature which is quite higher than the

maximum temperature allowed for n-hexadecane (500).

Carbopack B treated with hydrogen at 1000O (commercial) was the

last packing material we worked with. n-Hexane exhibited again two
peaks with negative dips after them (Fig. 25). Arsenic(III) chloride
did not appear at 140° in 80 minutes.
TM-HL-2 35
page 27

2.4. Conclusions

The major difficulty in the separation of metal halides is in
finding a non-reactive packing material capable of use at the
elevated temperatures required. At the end of our literature
survey we have concluded that nobody had complete success about

this subject quantitatively.

Qualitative separations would not be sufficient for our work
and quantitative results were aimed at without any further help

of the literature.

There is a close relationship between column packing material and
the substances investigated by gas chromatography. Having a very
sensitive detector for chlorides and the necessity to decrease
the concentration of metal chlorides caused us to use an organic
solvent and eventually created another class besides metal chlorides
HC1l and chlorine. That was really our major difficulty and we had
extra peaks for n-hexane when chromatographed on the packing ma-
terials used except n-hexadecane. Since chlorine, HCl and some
metal chloride peaks had retention times equal to those of extra
peaks and quantitative results were aimed at, we insisted on
eliminating these unexpected peaks by trying different packing

materials and were able to do it with n-hexadecane only.

With all our packing materials, four metal chlorides which were
tried either did not appear or gave extra peaks. From the presence
of these peaks, unstable baselines and tailings we conclude that
there are interactions between the packing materials and the
samples. Those peaks of the metal chlorides with the same reten-
tion time on SE-30 make us to think that it is a common reaction
product. The extra peaks were the results of not only these reac-
tions but also of the reactions between packing materials and
hydrolization and oxidation products of metal chlorides. With the
introduction of chlorine and HCl, too many peaks were obtained.
TM-HL~-235
page 28

When the concentration of chlorine was increased, the number of
unexpected peaks also increased. The metal chlorides are highly
corrosive, volatile and very easily hydrolized. To avoid this, we
prepared the samples under nitrogen atmosphere. However, because
the amounts of moisture and oxygen were quite high in the glove-
box, hydrolization and oxidation of the metal chlorides could

not be avoided. Opening the small bottles, to take metal chloride
samples for injections naturally increased the degree of oxidation
and hydrolization. This was observed easily from the precipita-
tion of metal hydroxides in the bottles. In further working, the
samples should be prepared under complete anhydrous conditions
and bottles with penetrable septums should be used instead of

those with stoppers used up to now to store metal chlorides.

(10)

In the results reported so far, Sie et al. -and Parissakis et

al.(g) had success to a degree in separating metal chlorides quan-
titatively. The packing materials which were used by them, namely
Kel F-40, Kel F-iO, Kel F wax, silicon oil DC-550, silicon rubber,
apiezon L, phasepack P should be tried. Although some of them had
been ordered by us more than 2 months ago, to try, they still
haven't arrived even after the completion of this report. One
important point is that some reporters had completely failed with
some of the above mentioned materials. Carbopack B (commercially

hydrogen treated) should be continued trying.

In the case of failure with all these packing materials, capillary

colums may be given trial.
3. References

(1)

(2)

(3)

(4)

(5)

(6)

(7)

(8)
(9)

(10)

(11)

(12)

(13)

Taube M.,
Ligou J.

Poterfield W.W.,
Tyree S.Y. Jdr.

Hermann J.A.,
Suttle J.F.

Fergusson J.E.,

Larson M.L.,
Moore F.W.

Strouts C.R.N.,
Wilson H.N.
Parry-Jones R.T.

Taube M.

Keller R.A.

Parissakis G.,
Vranti-Piscou D.
Kontoyannakos J.

Sie S.T.,
Blumer J.P.A.,
Rijnders G.W.A.
Freiser H.

Keller R.A.,
Freiser H.F.

Keller R.A.

TM-HL-2 35
page 29

Molten Chlorides Fast Breeder Reactor,
Problems and Possibilities.

EIR-Bericht Nr. 215, Eidg. Institut fir
Reaktorforschung, Wirenlingen, 1972

Inorganic Synthesis,
Vol. 9, P 135

Inorganic Synthesis,
Yol: 5, p. 143

in V. Gutman (ed),
Halogen Chemistry, Academic Press,
London and New York, 1967, p. 249

Inorganic Chemistry, 3(1964) 285

Chemical Analysis

Clarendon.Press, Oxford, 1962, p. 117
The Possibility. of Continuous in-core
Gaseous Extraction of Volatile Fission

Products in a Molten Fuel Reactor.
EIR-Bericht Nr. 257, 1974, p. 5

J. Chromatog., 5 (1961) 225

J. Chromatog., 52 (1970) 461

Separation Sci., 1 (1966) 41

Anal. Chem., 31 (1959) 1440
in R.P.W. Scott (ed)

(1960), Butterworth,

Gas Chromatography
London, 1960,

J. Chromatog., 5 (1961) 226

p. 301
TM-HL-235

page 30

(14) Juvet R.S., Anal. Chem., 32 (1960) 290

Wachi F.M,
(15) Tadmor J J. Inorg. Nucl. Chem., 23 (1962) 158
(16) Tadmor J. Anal. Chem., 36 (1964) 1565
(17) Tadmor J. J. of Gas Chrom., 2 (1964) 385
(18) Wilke J., J. Chromatog., 18 (1965) U482

Losse A.,

Sackmann H.

(19) Dennison J.E., Anal. Chem., 37 (1965) 1766
Freund H.

(20) Brazhnikov V., J. Chromatog., 38 (1968) 244
Sakodynski K.

(21) Zado F.M, in A.B. Littlewood (ed), Gas Chromatography
Juvet R.S. 1966, Elsevier, London, 1967, p.283

(22) Stumpp E. z. Anal. Chem., 242 (1968) 225

(23) Parissakis G., Chromatographia, 3 (1970) 541

Vranti-Piscou D.,
Kontoyannakos J.

(24) Tranchant J. Practical Manual of Gas Chromatography
Elsevier, London, 1969, p. 5
(25) Coates V.J., Gas Chromatography,
Noebels H.J., Academic Press, New York, 1958, p. 20
Fagerson I.S.
(26) Ambrose D., Gas Chromatography
Ambrose B.A. George Newnes, London, 1961, p. 16
(27) Di Corcia A., Anal. Chem., 43 (1972) 1634

Bruner F.
\

-

’ min mia

Fig. 2 n-Hexane

Packing mat.
Te = 150°C

I. _
3

SE-30

Fe: 24 ml/min.

TM-HL-235
page 31

J

4%\:4 S ma

Fig. 3 012 in n-Hexane
Packing mat. SE-30
Te = 150°C
Fe: 24 ml/min
Fig. 4

b—

TM-HL-235
page 32

. _— e — T

012 in gas form

Packing material = SE-30
Te = 150°¢C

Fe: 24 ml/min.

TM-HL-235

Cl2 in gas form

Packing material = SE-30
Te = 150°¢C

Fe: 24 ml/min.

page 32

o)

= ==t
|
Gg) o s
hD ~ ¢
{

e
i S
e T
{ 1 i - ':! imf\ ‘Lw—\ m}; F_ 5% ‘“ 1

TM-HL-235

page 33

— ——]

A
sCl3

Packing material = SE-30
Te = 125°C
Fe: 24 ml/min.

TM-HL-235

page 34
o
-
=y
\ : \ * =
\ F\ l
- —
I -
‘101-)‘ a.mh pbin by Bmor Ban Fax *.«-4 !
Fig. 6 AsCl3
Packing material = SE-30
Te = 150°¢C Fe: 24 ml/min.
- -
I =
J ~
!
-
NF\
q
| &
; [ 2 min S G- £
Fig. T ASCl3
Packing material SE-30
Te = 175°C Fe: 24 ml/min.

TM-HL-235
page 35

Fig. 8

AsCl3

Packing material:

Te = 200°¢
Fe: 24 ml/min

SE-30

TM-HL-235

page 36
| B X
|
|
o | N |
- W |
|
f
|
o t K
|
‘n % % ]
=}
{ !
|
) : - o
|
~J
-nh #

Fig. 9 AsCl, ‘Fig. 10 AsCly
Packing material: SE-30 Packing material:
Te = 90°C ot
Fc: 24 ml/min i 18

Fe: 24 ml/min
L°‘3 (“ R LA\

Q.10

Fig. 12

200 249 o 30 Cho S0 6o
VTG_ x \_Q" . —

-1

Log (tg-t,) vs T = for

AsClB on SE-30

TM-HL-235

page 37

o

A
sCl3

Packing material
SE-30

Te-110°C
Fe: 24 ml/min.
H- P 4'0\.}; 3:&5\.-

Fig. 13 T:'LCl,4

Packing material:
SE-30

Tec = 150°C Fe = 24 ml/min.

b

: .n‘\h\ an z j mia ~Min ?m.‘«,

Fig. 14 AsCl3 (more concentrated)
Packing material: SE-30
Te = 150°C  Fe: 24 ml/min

e

Q¢ o3ed
G¢e-TH-NWL

£ ? o ’ ~
o — e : =
o — . -
~ W e

- N
2 min n men $ ”";’1 " )
“ \\
) . im}; 2’»»‘«. 3 —— e,
Packing material = SE-3%0
Te = 200°C

Fig. 16 SbCl5
Packing material = SE-30
Te = 150°C Fe: 24 ml/min.

Fe: 24 ml/min

6¢ o3ed
G¢2-TH-IL

TM-HL-235

page 40

v W
W i T
TS )
,m,4 m
S
w
| —
\ - Qo ?‘ o
Rig. 17 SbCl5
Packing material = SE-30
Te = 150°C

Fe = 24 ml/min.
Fig. 18

n-Hexane

Packing mat.: Carbopack A

Te

200°¢C
24 ml/min.

o L e

Pig. 19

n-Hexane
Packing mat.:
Te = 200°C

Fe 24 ml/min.

Carbopack A

Th @3ed

G¢2-TH-NWL
TM-HL-235

page 43
S & i |
!
: | o o ;
N -
=
& |
* | |
§ ~ w |
|
| o
b o N
. .--—n—yu-u-T—J &—-stLi!'F l . =

Fig. 21 n-Hexane
Packing mat.: Carbopack A
Te = 60°C
Fc = 24 ml/min.
Fig. 22

# i
LR

n-Hexane
Packing mat.:
Te = 40%C

n-Hexadecane

U

36

tty o3ed
G¢2-TH-IWL

TM-HL-235
page 45

L EE———

\\“h-..
min 2 . 4 : | C
Fig. 23 012 gas Fig. 24 HC1 gas
Packing mat.: Packing mat.:
n-Hexadecane n-Hexadecane

Te = 40°C Te = 40°C

n-Hexane

Packing mat.: Carbopack B-HT
Te = 100°C

Fc = 48 ml/min.

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—--——:~fc == : ‘mt*lM[Nl*
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