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Патент USA US3086942

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Patented Apr. 23, 1963
and increases of the proportion of higher polyphenyls
is an undesirable tendency.
This is true as well for other
Robert 0. Bolt, San Rafael, and William W. West, El
Cerrito, Cali?, assignors, by mesne assignments, to the
hydrocarbons, e.g., partially hydrogenated or alkylated
United States of America as represented by the United
produces a marked reversion or conversion of higher
The present invention is predicated on the discovery
that catalytic hydrogenolysis of ?di?erent polyphenyls
States Atomic Energy Commission
molecular weight constituents of aromatic and especially
No Drawing. Filed Nov. 3%, 1959, Ser. No. 856,321
polyphenyl mixtures having undesirable characteristics
3 Claims. (Cl. Zita-493.2)
10 into lower molecular weight mixtures of more useful and
desirable coolant-moderator types. Most unexpectedly
The present invention relates, in general, to the pro
hydrogenolysis, i.e., ring cleavage occurs with little ring
duction and recovery of polyphenyl coolants from in
hydrogenation which might have been expected. Thus,
tractable polyphenyl tars or residues and, more particu
highly damaged reactor coolant-moderator materials may
larly, to the treatment of intractable, insoluble tarry resi
dues obtained from coolants or moderators employed in 15 be reconditioned or various component fractions thereof
separated and treated to provide a material which is
nuclear reactors for conversion into useful moderator
highly satisfactory for reuse in the reactor.
coolant products.
Accordingly, it is an object of the present invention
Varieties of aromatic hydrocarbons have been utilized
to provide a method for reconditioning coolant-moderator
or have been proposed or investigated for use as coolants
materials for use in a nuclear reactor.
or moderators in nuclear reactors including polyphenyls,
aromatic condensed ring compounds, aromatic ethers and
alkylated aromatic hydrocarbons. Polyphenyl hydro
Another object of the invention is to employ a catalytic
hydrogenolysis treatment for converting higher molecular
weight reactor coolant-moderators into more desirable
Still another object of the invention is to provide a
lytic and pyrolytic resistance and other requisite proper 25
carbons, especially biphenyl, the terphenyls and the qua
terphenyls are suitable for such use due to superior radio
ties as disclosed in the ?copending application of Rep
pino J. Fontana et al., S.N. 599,352, ?led July 23, 1956,
method of converting high molecular weight intractable
tarry components of aromatic hydrocarbon coolant
now abandoned. Ordinarily, mixtures of a ?uid nature
or low melting point solids corresponding to lower aver
age molecular weights or eutectic mixtures are preferred.
moderators into coolant types suitable for use in a nuclear
Upon long continued use in the high temperature intense
radiation environment of the reactor the organic mixtures
alytic hydrogenolysis treatment for reconditioning poly
show increases in viscosity with higher molecular weight
materials being formed therein. Eventually, insoluble
A further object of the invention is to employ a cat
phenyl moderator-coolants for use in a nuclear reactor.
Other objects and features of the invention will be
come apparent by consideration of the following de
tailed description.
The present invention contemplates the treatment of
aromatic hydrocarbon mixtures employed as coolants and
moderators or higher molecular weight fractions obtained
high molecular weight materials may form which materials precipitate to plug reactor passages and create a
hazard to further operation of the reactor. Accordingly,
in conventional practice the mixture employed in the re
actor is periodically replaced or reconditioned by sep 40 therefrom by distillation, extraction, selective precipita
tion, etc. The process is especially applicable to the
arating the tarry constituents by distillation, precipitation,
treatment of polyphenyl mixtures such as the damaged
extraction, etc. The tarry residues obtained in such re
conditioning operations represent an expensive loss of the
biphenyl-terphenyl coolant-moderator employed, e.g., in
the OMRE and to other mixtures including, initially, bi
coolant or moderator material and the indicated changes
of composition of the coolant lead to greater pumping 45 phenyl, terphenyls and quaterphenyls. Usually such in
itial mixtures are ?uid or have a low melting point and
cost, lower heat transfer as well as other higher oper
may comprise a considerable proportion of biphenyl with
ating costs for such a reactor.
terphenyl and quaterphenyls or eutectic mixtures. Alkyl
Nuclear reactors employing organic moderators and
ated biphenyl, terphenyls and minor amounts of quater
coolants are well known in the art. A reactor employing
biphenyl as a moderator is disclosed in vU.S. Patent No. 50 phenyls may likewise be employed. For the purposes of
the invention, a radiation ?damaged mixture is one that
2,708,656, issued May 17, 1955, to E. Fermi et al. The
has a higher average molecular Weight or undesirable
use of organic liquids as coolants is also disclosed in
amounts of high molecular compounds and evidencing
variously higher insoluble tar content, higher viscosity,
ing,? Glasstone, Van Nostrand Co., Inc., 1955. A bibli~
ography of publications relating to such reactors is pre 55 melting point, etc. Certain polyphenyl synthesis meth
Chapter 8 of ?Principles of Nuclear Reactor Engineer- _
ods may produce mixtures of too high a molecular weight
which mixture may likewise be treated. A damaged re?
actor or coolant material of the character described may
.R. W. Bowring, AERE Report inf/Bib 105. Moreover,
comprise discarded material, a bypass stream obtained
biphenyl-terphenyl mixtures have successfully been uti
lized in the OMRE (organic moderated reactor experi 60 from a reactor coolant system, residues obtained by selec
tive separation from a reactor coolant circuit, or the like.
ment). C.f. ?Details of OMRE? Nucleonics, vol. 14,
In accordance with the invention such a material is
No. 5, page 22, May 1956.
subjected to a hydrogenolysis treatment wherein a sub
The reactions which occur upon radiolytic pyrolysis of V
stantial portion of the higher molecular weight compo
the initial coolant-moderator mixtures are complex but
nents are converted into lower molecular weight com
generally tend to increase molecular weight, e.g., by con
ponents such as biphenyl, terphenyl and alkylated deriva
verting lower polyphenyls to higher, polymerizing or com
tives thereof which constitute superior reactor coolant
bining unsaturated radiolysis products, etc., to progres
moderator types. With source materials not originally
sively produce a less desirable coolant and tinally a
too severely damaged the reaction product, after ?ltering
material which is not suitable for further use and which
70 and ?being separated from gaseous or low-boiling compo
must be replaced. Any substantial change such as re
nents, is reintroduced into the operating reactor as recon
sented in ?Selected Abstracts on the Use of Organic Ma
terials as Reactor Moderator-Coolants,? G. Naish and
duction of the proportion of lower molecular polyphenyls
ditioned material. With highly damaged materials, such
cate ring cleavage which eitectively divides high molecu
as the insoluble, intractable tarry residues the reaction
lar piolyphenyls to provide the desired lower molecular
product may be fractionated, e.g., in distillation or
coolant-moderator compounds. It will be understood
vacuum distillation apparatus and the recovered lower
molecular weight, components may be used as makeup
from the foregoing that if the original mixture includes
moderator-coolant or otherwise admixed with other com- 5 polyphenyls of a higher molecular Weight than terphenyl,
ponents to provide moderator-coolants as in conventional
e.g., quaterphenyls, et seq., a general lowering of molecu
la-r weight will be obtained with substantial amounts of
In the hydrogenolysis treatment the damaged coolant-
biphenyl and ter-phenyl being produced. Such mixtures
moderator mixture is contacted with hydrogen in the
would correspond or could be easily blended to corre
presence of a hydrogenolysis catalyst under high pres- 10 spond to the superior coolant-moderators disclosed in
sure and at elevated temperatures in appropriate batch
the aforesaid copending application of Fontana et a1.
or continuous flow high pressure equipment of convenand publications supra. Hydrogenated polyphenyls
tional design. Generally speaking, it is contemplated that
which are produced under indicated conditions are less
so-ca,11ed ?acid? cracking and mild hydnogenation catadesirable compounds since radiation damage resistance is
lysts are effective in producing hydrogenolysis of higher 15 lower.
polyphenyls. More speci?cally A1203 (alumina) and
Further details will be presented in the following
certain mixtures of A1203 with CuO have been so em?
speci?c example illustrating the manner of operating the
ployed. Suitable operating conditions are presented in
process ?of the invention:
Table I, infra.
Standardized amounts of terphenyl representative of
higher molecular weight polyphenyls were reacted with
Bmad range
Preferred range
hydrogen under high pressure ?and at an elevated tem
perature with various combinations of cracking and hy
Timerhmns-?o-------------- -- 01-8-0 ------------- -- 4-181)-
drogenation catalysts.
_______ __'_'_' Egg-�81
Ram 0? ?mpwnd: A1103? FY2�_%,825=�-25=� 't� 112333651211 to
' ' '
The reagents comprised Mon
25 Same m-terphenyl recrystallized from ethyl alcohol;
aluminum oxide powder (Baker, reagent grade) as crack
' ' '
ing catalyst; and copper oxide powder (Mallincrodt GP.)
as hydrogenation catalyst. The reagents were charged
General comments as to the effects of the speci?c
into a hydrogenation bomb and the bomb pressurized se
catalyst type are summarized in the following chart:
30 'quentially to 500' and 250 p.s.i.g. with H2 to eliminate
Effect on biphenyl formation
Hydrogenation (OuO) _ _
Increasing amounts decrease biphenyl
Cracking (A1203) ...... ..
Increasing amounts probably increase
biphenyl formation.
E?eet on ring hydrogenation
E?ect on higher polyphenyl formation
Increasing amounts increase ring hydro
Increasing amounts probably reduce
h?gher polyphenyl formation.
Increasing amounts probably increase
No ring hydrogenation obtained with
cracking catalysts alone.
higher polyphenyl formation.
Norm-General comments: (1) Both ring-hydrogenation and hydrogenolysis reactions are strongly a?ected by temperature and reaction time.
(2) It is likely that the catalyst for optimum operation (low conversions to higher polyphenyls and hydrogenated polyphcnyls and high conversions to
biphenyl) will be primarily a cracking catalyst, with a small amount of a mild hydrogenation catalyst.
Poly-phenyls can be represented by the formula
air and ?nally the ?desired hydrogen pressure was intro
duced. The bomb was then placed in a rocking hydro
50 genation furnace ?and heated to the desired temperature
wherein It may be zero or a larger integer, i.e., 1, 2, 3
with reagent proportions and other conditions as sum
Presumably, polyphenyl tars contain substantial
marized for several runs in the following Table II:
Summary of Conditions for Terphenyl
Hydrogenolysis Runs
Time, hours _________________________________ ._
4 ____________ __
Temperature, � F__.
_ 800
Initial pressure, D.S.i.g_
1,500 ________ __
5G0 __________ -_
. _ _ . _ __
2 __
Terphenyl . _ _ _ _ _ _ _ _ . .
Terphenyl charge, g.
_____________________________________ __
____ __
Catalyst charge, g.:
______ ..
500 ____ __
A1203 _______ __
CuO _____________________________________ _.
Ratio of compound: AhOyCuO charges ..... ._
amounts of materials in which n is 2, 3 or larger while
in desirable moderator-coolants n is 0, 1 with at most
minor amounts of quaterphenyls (11:2). The term
?hydrogenolysis? as employed herein is intended to indi
Following hydrogenolysis the reaction products were
removed from the bomb whereupon it was noted that the
CuO in each instance was reduced to the metallic state.
Catalyst was separated from the mixture and the mix
ture analyzed by means of a mass spectrograph with
results presented below in Table III:
containing higher polyphenyls, the steps comprising with
drawing said damaged moderator-coolant from the
Summary of Mass Spectrometer Analysis of Terphenyl
Hydrogenolysis Runs
Probable identi?cation
6064-392 6064-422
Benzene ___________________ __
?l52____ Biphenylene
154--? Biphenyl
?ijiinieiiizi-Ec'e't?ii'e this}
cene phenanthrene_
'I?erphenyl ________________ __
234-___ Tetrahydro-terphenyl
Hexahydro-terphenyl _____ __
242.-? Dodeeahydro-terphenyl
276"? ____________________________ __
278____ ______________ __
306..-- Quaterphenyl___
Hexap?nenyl _______________ __
535-___ Heptap?nenyl
1 In calculating the components in 6064-35, certain assumptions concerning sensitivities
had to be made. These assumptions are listed on 6205-15.
1? Polyphenyl values for 6064-39, ?42, and ?45 are normalized to 100%. These poly
phenyls comprise approximately 96% of the total product for these three runs.
3 x denotes peak presence in small but undetermined amounts.
NOTE.-?Figures in table refer to liquid volume percent concentration.
nuclear reactor, contacting an admixture of said damaged
reactor coolant-moderator and hydrogen simultaneously
the e?ectiveness of the mixtures as coolant-moderators, 35 with a catalyst including an alumina acid cracking catalyst
and Q10 mild hydrogenation catalyst present in the ratio
particularly when the mixtures are employed for makeup.
range of 25:2:1 to 25:4:0, respectively, at a temperature
The lower boiling materials ?could, of course, be sepa
in the range of about 800 to 1000" F. and a pressure in
rated, e.g., as by distillation and employed as coolants
the range of 500 to 1000 p.s.i.g. to cause hydrogenolysis
and the higher boiling material reprocessed.
While there has been described in the foregoing what 40 of said higher polyphenyls to produce lower molecular
Weight polyphenyls and alkylated derivatives thereof in
may be considered to be preferred embodiments of the
the reaction mixture, and then returning said coolant
invention, modi?cation may be made therein without
moderator mixture to the reactor.
departing from the spirit of the invention and it is intended
in practice the small proportions of polyphenyls above
quaterphenyls shown would not seriously detract from
to cover all such as fall within the scope of the appended
vWhat is claimed is:
1. In a process for producing a polyphenyl moderator
coolant from a mixture including higher polyphenyls, the
steps comprising contacting an admixture of said higher
3. The process as de?ned in claim 2 wherein there is
included the operation of fractionating said reaction mix
ture prior to return to said reactor.
References Cited in the ?le of this patent
polyphenyl mixture and hydrogen simultaneously with a 50
catalyst including an alumina acid cracking catalyst
Burk ______________ __ Mar. 10, 1936
Ipatieff et al. __________ __ Oct. 6, 1942
together with a lesser proportion of CuO as a mild
Miles ______________ __ Mar. 14, 1944
hydrogenation catalyst in the ratio range of 25 :2:1 to
25:4:(), respectively, at a temperature in the range of
Ipatieff et al. ________ __ Aug. 8, 1944
Jenkins ____________ __ Dec. 12, 1944
about 800 to 1000� F. and a pressure in the range of
Pitzer ______________ __ July 23, 1957
500 to 1,000 p.s.i.g. to cause hydrogenolysis of said higher
Colichman ____________ __ Jan. 9, 1960
polyphenyls to produce lower molecular ?weight poly
phenyls and alkylated derivatives thereof in the reaction
mixture, and fractionating said lower molecular weight
polyphenyls from said reaction mixture.
2. In a process for reconditioning a radiation damaged
polyphenyl nuclear reactor coolant-moderator mixture
Atomic Energy Commission Document: ANL?5121,
Engineering Properties of Diphenyl, Anderson, Aug. 11,
1953, pp- 14 and 15.
Catalysis, Sophia Berkman et al., pp. 629 and 847.
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