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Pmmd Nov. 5,- i946
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webbma'rammn. we, mean.
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Universal 0!! Products Com
‘ pany,¢hlcago,lll._,acorporatlon of Delaware _.
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Noni-swine; AppllcationMa-eh 12, 1943,
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{(01. 2514-250)
The prés'entainvenuon. is ‘comma time; "sad. i a about 16
percent‘ by weight of the
" provements in processes ‘for, vthe, manufacture - or ' " anhydr'ous‘alumina; will serve to assist the dis
catalysts ‘adaptedfor use inv'arious processes in- { . persion of the alumina’lto form the. hydrosol. In
- volving' the treatment or" conversion ofrorgiamc 1
substances,
and pa 4icularlylprocesses involving
‘
a large number of instances satisfactory disper
sion may be‘ obtained with amounts of ammonium
conversion'reaction‘s amonguhydrocarbo'ns.
1
chloride of the order of from about 2 to about 3
‘ Catalysts prepared: by the‘ present improved , percent by weight of the alumina. Other ammo
process have been found to ‘exhibit superior activ
ity in such processes as the reforming ‘of m.
' antiknock value ‘gasolines and naphthas, to in
crease antiknock characteristics;
_
_
In accordance with the broad concepts of the
present invention-a precipitated and v'puri?ed
hydratedaluminum oxide is composlted with a
'_ relatively small am‘ountjof an agentwhich is
, effective in dispersing orypeptizing the hydrated
aluminum oxide. "I'he1Jmixture of alumina and
peptizing agent'is added" to‘ water to form a sol
of alumina, and compounds are added to the sol
nium salts, such vas ammonium'sulfate, ammo
nium nitrate, and'th'efother halidesalts of am
10
.
..monium maybe used alternatively in different
proportions;
-
The function of the. ammonium compounds in
promoting the- dispersion of hydrated aluminas
in aqueous mediais evidently to peptize the
alumina. This e?ect has‘. not been previously
noted in connection with volatile ammonium
compounds, particularly when they are used in
the small amounts which we have found to be
su?lcient for promoting the dispersion of the
which are soluble in ;the ‘aqueous medium and 20 alumina. The desired dispersion'may be further
which are capable of yielding a catalytically ac
assisted by adding the mixture of alumina and
‘ tive substance. ' Subsequently the liquid is evap
the ammonium salt to a mildly acid aqueous
orated and the catalyst developed by controllably
medium. Thus acids, or other solutions having
" heating the residual solid materials.
a pH value as low as 2, may be used as the con
In one speci?c'embodirnent the present inven 26 tinuous phase in the formation of the desired
tion comprises a process for the manufacture of
alumina hydrosol. -' The compound or compounds
catalyst composites» consisting essentially of
which serve as the source of the other catalyti
‘aluminum oxide and'other'catalytically active
cally active substance may be added to the sol
oxides by adding to a puri?ed hydrated aluminum
after it has been formed or, in some instances,
oxide a minor proportion ofQan ammonium salt, 80 the compound may be present in the aqueous
thoroughly mixing the alumina and the ammo
medium in which the hydrosol is developed.
nium salt, forming an alumina hydrosol by add
_The process of the invention is particularly
ing the mixture to an aqueous medium, adding
applicable to the production of catalysts in which
a compound capable of yielding a catalytically , alumina is a major constituent and oxides such.
active substance, thereafter evaporating the solu
as molybdic oxide-are relatively‘minor constitu
tion‘to. substantial dryness and further heating
ents. Such catalysts are particularly useful in
the residual material thus obtained to develop
various hydrocarbon conversion reactions includ
the catalytic composite. 7'
‘
'
'
‘
ing hydrocarbon hydrogenation reactions in
The improvement, which characterizes the: which hydrogen is simply added to saturate un
present invention and differentiates it from pre— 40 saturated hydrocarbons; in the so-called destruc
viously known-processes in the manufacture of ,
tive hydrogenation processes in which decompo
catalysts is'in the use of minor proportions of
sition and recomposition reactions occur in the
ammonium salts with hydrated aluminum oxides
presence of hydrogen in the dehydrogenation of
whereby hydrosolsare, readily formed in which
organic compounds such as hydrocarbons; in the
the alumina exists ‘in a'very ?ne state of sub 45 reforming of gasolines to improve antiknock
division so that whensubstances are added which
properties, etc. Alumina-molybdena catalysts
are capable of yielding other catalytically active
are particularly useful in the so-called "hydro
oxides, there is an intimate contacting of ‘the
forming” process in which gasolines inferior in
alumina and the added substances prior to and
antiknock value are heated in contact with cata
during the evaporation of the aqueous medium 50 lysts in the presence of hydrogen to increase
and the production of the catalyst composite in
their antiknock properties by reactions which
the ?nal heating step; ' :Ammonium chloride has
may involve cracking, cyclization and isomeriza
been found to be particularly suitable for'addl
tion, the hydrogen in?uencing the reactions in
tion to hydrated alumina, to assist the hydrosol
the direction of increased antiknock value with
‘formation and amountsof this salt. varying from 65 out. material consumption thereof and in gen
2,410,658
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.
3
w
'
.
eral lowering carbon deposits on the catalysts.
Other catalysts which may be made by the
process of the present invention include those
comprising alumina and the oxides of chromium
_
4
dration of the alumina. The best proportions of
alumina and peptizing agents can be determined
by small scale laboratory tests prior to the use
and/or tungsten, which metals are listed in the
of the process on _a commercial scale.
In accordance with the present process a com
left-hand column in group _VI of the periodic
pound which is capable of yielding a cataiyticaliy
table along with molybdenum; or catalysts com
. active material may be added to the aqueous
prising alumina plus metals or oxides of metals
medium prior to the formation of the alumina
of the iron group including iron, nickel and co
sci or after the sol has been formed. After thor- '
balt. Other catalysts which may he made in ac 10 ough mixingto insure intimate contacting of the
cordance with the process of the present inven
alumina particles and the solution of the dis
tion include those consisting‘ of alumina and
the oxides of the elements in the left-hand col
umn of group IV comprising‘ cerium, thorium,
‘zirconium and titanium; and the left-hand col 15
solved compound, the total mixture is heated
to evaporate the water. After the water has
been vaporized the residual solid material is
dried at sometemperature within the range of
umn of group V comprising vanadium, colum
hium and tantalum. These various catalysts
may be used in different hydrocarbon conver
sions such as cracking, hydrogenation, reform
from about 250 to 500° F. After the volatile con
tent of the residue from this step is reduced to
' about 10 percent, the residue may be further
heated to develop catalytic properties. During
ing, dehydrogenation, dehydrocyclization, and 20 this ?nal heating, hydrates of alumina, break
isomerization of paraffin and naphthene hydro
down to form lower hydrates and eventually all
carbons.
‘
.
,
As a basis for the present invention we have
found that certain de?nite types of hydrated
aluminas may be dispersed in ‘aqueous media
to ‘form hydrosols when mixed with minor
amounts of ammonium salts. The dispersion
may be effected most readily in the case of hy
drated aluminas which have been precipitated
of the water of hydration may be removed and
substantially anhydrous gamma alumina pro
duced. If the heating is continued at too high
a temperature, there will be some formation of
the alpha modi?cation of alumina, and the cata
lytic properties of the composite will diminish
generally in proportion to the amount of alpha
alumina formed.
'
from solution and puri?ed by washing to remove 80 As previously indicated, the catalyst composite
a substantial proportion of the soluble compound
comprises one or more substances in addition
present. One class of hydrated aluminas which
to alumina. The choice of the non-aluminifer
can be satisfactorily utilized includes aluminas
ous substances added will depend to a large ex
which have been precipitated by adding volatile
tent upon the process in which the catalyst is
basic precipitants such as ammonium hydroxide, 35 to be employed. Catalysts produced by our
amonium carbonate, etc., to aqueous solutions
method are not necessarily equivalent in all proc
of aluminum salts such as aluminum chloride,
esses nor are those which are useful in the same
aluminum bromide, aluminum iodide, aluminum
process necessarily exactly equivalent to each
other. However, for whatever purpose they may
aluminas as originally obtained are usually gam 40 be useful the catalysts prepared by our method
‘ sulfate and aluminum nitrate. These precipitated
ma alumina mono-hydrates which change over
are superior to those prepared by the conven
into gamma alumina tri-hydrates on prolonged
tional forms of manufacture involving the im
standing in an alkaline medium. Such precipi
pregnatlon of alumina.
tated aluminas may be washed with’ water vor
The compounds of the added substance which
weakly acidic solvents to substantially complete 45 may be used in manufacturing catalysts by our
ly remove any excess of precipitant and of am
method may vary somewhat depending upon
monium salts formed by the interaction of the
their properties and also upon the particular
alkaline precipitant and the aluminum salt. It
substance which is to be added ‘to the hydrated
is essential to the success of the present types
alumina. In the case of molybdena-containing
of operations that the soluble materials be 50 catalysts and catalysts containing certain other
washed out so ‘that the amount of added am
components which are useful for hydroforming
monium salt can be regulated to permit, the best
gasolines and naphthas, the metal should be in
dispersion of the alumina.
.
the acid radical. For example, ammonium-mm
Other types of hydrated aluminas which may
lybdate should be used in the manufacture of
be utilized as starting material in the present 55 alumina-molybdena catalysts according to our
process are those which ‘have been formed by
improved process.
treating solutions of alkaline metal aluminates
The compounds which are‘to be added to the
with carbon dioxide. Such precipitated aluminas
wet hydrogel should be soluble in substantial
are commonly washed to remove alkaline metal
quantities, preferably in water, and should be of
carbonates and bicarbonates and then partially 60 a type which is readily decomposable in the ?nal
dehydrated to form the so called “activated”
calcining treatment to which the composite is
aluminas of commerce which are used as ab
subjected. The compounds should preferably be
sorbent materials for the puri?cation of various
of such a nature that the decomposition product
liquid media and as bases for catalytic com
thereof consists of the oxide of the metal contain
posites made by impregnating the granular solids
with decomposable substances capable of yield
ing no undesirable residues as a constituent of
the catalyst. The. products of decomposition
other than the metal oxide should be readily vol
We have found that aluminas varying consid
atilizable under the conditions of subsequent heat
erably in their combined and-total water con
tents can be dispersed in aqueous media by using 70 ing. Thus, for example, the composite of the
wet alumina hydrogel with ammonium-molybdate
varying amounts of volatile ammonium salts in
solution after evaporation and subsequent heat
admixture with them. The choice of ammonium
ing would yield a composite containing oxides
salt and the optimum amount for insuring satis
of aluminum and molybdenum, but without any
factory sol formation will vary with the method
of manufacture and the degree‘and type of hy 75 undesirable residue, which is a catalyst poison,
ing catalytic oxides.
'
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:41
2,410,668
6
from the compound which was the source of the
molybdena.
The one possible exception to this might be in
including those of a batch and of a continuous
character and they may be used in the form of a
powder or as granules, pellets or extrudates. In
one type of continuous operation prepared .par
ticles are placed in reaction chambers through
which various hydrocarbon reactants may be
posites may desirably contain magnesium oxide
passed at controlled temperatures, pressures and
in relatively minor amounts; usually less than
rates of ?ow. In powdered form the catalysts
about 5 per cent. The compound added to the
may be used in ?nely divided condition so that
wet alumina gel may comprise such materials as’,
for example, magnesium chromate when the cat 10 the so-called “?uid” type operation may be em
ployed wherein the vapors of hydrocarbon react
alyst is to contain chromia, magnesia and alu
ants are caused to carry relatively large weight
mina. Alkali metal molybdates, chromates, etc.,
proportions of the powdered catalyst through a
are to be avoided where alkali metal compounds
reaction zone, after which the catalyst is sepa
exert a poisonous effect on the ?nal composite,
as they do in composites of this kind useful for 15 rated by settling or centrifuging and recycled to
cases in which a stabilizing compound is desired
as a component of the catalyst; thus certain com
further use as long as its catalytic activity is suf
?cient or wherein the vapors of hydrocarbon re
actants pass through a mass of powdered cata
lytic material and cause its circulation in the re
radical, the remaining part of the compound 20 actor without substantial carry-over of the cat
alyst. comprising a component which is either a desir
We claim as our invention:
able constituent of the catalyst because of the
1. A process for producing catalysts which com
stabilizing eifect, or the catalytic effect which it
prises mixing a precipitated and puri?ed hy
lends to the composite; or else it should be vola
tilizable at the decomposition temperature of said 25 drated alumina, with from about 1% to about
dehydrogenation, reforming, etc.
Thus the added compound which is to be the
source of the catalytic component may comprise
a compound in which the metal is in the acid
added compound.
,
10% by weight of an ammonium salt, dispersing
the resultant mixture in an aqueous medium to
form an alumina hydrosol, adding to said hydro
the catalyst in relation to the alumina in the
sol a metal compound soluble in said aqueous me
?nal composite may vary over a considerable '
range, the alumina being the major constituent. 30 dium and capable of yielding a catalytically ac
The amount of non-aluminiferous component of
In the case of alumina-molybdena composites,
catalysts of maximum activity, as shown by the
increase in octane number obtained when gaso
lines or naphthas are hydroformed, will usually
contain molybdena in amounts of the order of
from about 6 to about 12 percent, although larg
tive metal oxide upon heating, evaporating the
resultant mixture to substantial dryness, and
heating the resultant residual material to con
vert said compound to the metal oxide.
er or smaller quantities may be used.
chloride.
In the
2. The process as de?ned in claim 1 further
characterized in that said salt is ammonium
3. The process as de?ned in claim 1 further
case of other added catalyticaliy active compo
characterized in that said aqueous medium is
nents, the percentage of the compound associ
ated with the alumina may vary over a consid 40 acidulated Water.
4. The process as de?ned in claim 1 further
erably wider range. For example, effective de
hydrogenation and dehydrocyclization catalysts
characterized in that the metal of said com
pound is an element from the left-hand column
containing chromia, include those in which the
of group VI of the periodic table.
amount of chromium sesquioxide in the alumina
5. The process as de?ned in claim 1 further
chromia composites varies from as low as 2 to as 45
characterized in that the metal of said compound
high as 30 percent.
is molybdenum.
The catalysts made by the present process have
6. The process as de?ned in claim 1 further
numerous advantages when compared with cat
characterized in that the metal of said com
alysts of the same chemical composition made by
conventional processes such as by impregnating 50 pound is chromium. '
7. The process as de?ned in claim 1 further
dried alumina particles with solutions of com
characterized in that said compound is ammonium
pounds capable of yielding catalytic oxides or by
co-precipitation methods wherein the catalytic
compounds are precipitated in the form of hy
molybdate.
8. A process for producing catalysts which
drated oxides along with the primary precipitate
of hydrated alumina. Apparently, the alumina
comprises mixing a precipitated and puri?ed hy
and the added catalytically active compounds are
thoroughly dispersed in each other in the cata
lysts made by our process, which may account
by weight of ammonium chloride, dispersing the
drated alumina with from about 1% to about 10%
resultant mixture in an aqueous medium to form
an alumina hydrosol, adding ammonium molyb
for the higher initial activities, higher stability 60 date to said hydrosol, evaporating the mixture of
in respect to loss of structure and catalytic prop
ammonium molybdate and alumina hydrosol to
erties on accidental overheating or continued use
substantial dryness, and heating the resultant
at high temperatures, better life after repeated
residual material to convert the ammonium
molybdate to molybdenum oxide.
use and reactivation, and lower carbon deposits
for a given conversion and easier regeneration. 65
The composites prepared by the present pro
cedure are utilizable in various types of processes
GLENN M. WEBB.
MARVIN A. SMITH.
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