Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
1~92~';7
The invention relates to a process for
catalytically oxidizing cyclic hydrocarbons using
catalytically-active metallic glasses.
Gertain amorphous metal alloys catalyze
6 hydrogenation reactions, for ex~mple, those of cyGlohexene
derivatives rG.V. Smith et al., J. of Catalysis 83 (1~83)
23~ or of carbon monoxide ti.e.~ Fisher-TrcpsGh ~eaction)
[A. YokoYama et al., Chemistry Letters ~1988), 195]. The
catalytic action is based on the amorphous state of the
metals. However, it has also been described that, in the
case of the system Pd80Si20, no significant differences
exist concerning the selectivity in the case of
hydrogenation reactions between the amorphous state and
the crystalline state ~B. Giessen et al., Mater Res. Soc.
Symp. Proc., Vol. 1~ (1982), 255].
For the most part, the surfaces and the state of
order of catalysts consisting of amorphou~ metals have not
been investigated sufflclently, ~o that the ~ompari~on
be~ween amorphou~ and cry~talline ~yB~em~ i8 not of any
significant meaning. It turned out, for example, that the
catalytical effectivene~s could n~t be deduce~ because of
a lack of knowledge of the connections between amorphous
and crystalline systems.
An object of the invention is to provide an
improved process for the oxidation of cyclic hydrocarbons.
A further object of the invention i8 to provide
catalytically-active metallic glasses for use in such
process.
It is to be noted that the term "metallic
glasses" as used herein is intended to have the same
meaning as the term "amorphous metals".
Accordingly, one aspect of the invention
provides a process for the oxidation of a cyclic
hydrocarbon, which comprises oxidizing said hydrocar~on in
~5 the presence of an activated, vitreou~ly-rigidif~ed,
metallic glass containing of ~i) titanium or zirconium and
(ii) vanadium, ~aid metalllc ~lass bein~ activated by
~k
~IZ~29~77
being subjected to an oxidative treatment prior to the
oxidation step or in situ during said oxidation.
Another aspect of the invention provides an
oxidation catalyst for use in the oxidation of cyclic
5 hydrocarbons, compri.sing an aGtivated, vitreously-
rigidified, metallic glass containing titanium or
zirconium and vanadium.
This application is a divisional of our
copending Application Serial No. 4~,421, filed ~uly 24,
1985, which describes and claims a process for
catalytically synthesizing ammonia from nitrogen and
hydrogen, which comprises using a vitreously-rigidified
metallic glass consisting of (i) Fe and Zr or (ii) Fe, Zr
and Mo, as the catalyst, as well as a process for the
production of an activated, vitreously-rigidified metallic
glass consisting of ~i) Fe and Zr or ~ii) Fe, Zr and Mo,
which comprises: ~a) producing the metalliç glass from
(i) Fe and Zr or ~il) Fe, Zr and Mo; and ~) without any
preactlvation treatment, activating ~he metallic glass in
situ using the ammonia-synthesis stream of hydrogen and
nitrogen, thereby providing the activated, vitreously-
rigidified metallic glass catalyst.
The metallic glasses change in such a way that
the transformation products, the nature of which has not
yet been exactly determined, show unexpected catalytic
effectiveness. Possibly, amorphous and crystalline
regions lie side by side in highly dispersed forms. It is
further noteworthy that the composition of the surface in
many cases is not the same as that of the catalyst body.
Starting out from amorphous alloys, cataly~ts
according to the invention can be produced which are not
obtainable according to hitherto known method~ for the
production of catalysts or from the corresponding
crystalline alloys.
The advantage of using amorpholls metals a~
starting materials for the production of çatalysts for use
in the invention lies, among other thin~s, ln the fact
that the metals in their am~rphou~ state are distri~uted
lZ9Z977
in an extraordinarily highly-dispersed manner; they may be
aggregations of only a few atoms. In the case of the
processes used hitherto for the production of catalysts,
.it i8 true that with regard to the degree of dispersion
c3reat advance~ have been achieved. However, none of the
industrially used processes leads to a similarly high
degree of dispersion as that achieved for the catalysts
u~ed in the invention.
The catalytically-active metallic glasses
contain at least one element from a subgroup of the
periodic system and at least one element from a main group
of the periodic system. In the invention, the elements of
Group VA are also counted as being in a main group.
The metallic glasses preferably contain an
16 element from Group IVA of the periodic system and at least
one element of Group IB, Group VA or Group VIII of the
periodic system. From group IV, ~he elements Ti and
especially Zr are preferred, while from Group IB the
element ~u, from Crollp VA, the element V ~vanadlum), and
from ~roup VIII, the elements Co, Ni, Pd and especially
Fe, are preferred.
The deslgnation of the groups of the psriodic
system utilized herein is based on the table of "The
Periodic System of the Elements" from "Roempps Chemical
Dictionary," Vol. 4, 7th Ed., (1974), page 25.~7.
Examples of suitable metallic glasses may ~e
chosen from those containing Zr and Fe, Ti and Fe, Zr and
Cu, Ti and Cu, Zr and V, Ti and V, Zr and Ni, or Ti and
Ni. Preferred examples are alloys with the formula
Feg1Zr9, FeglTi9~ Fe24Zr76, Fe24Ti76~ Ni24Zr76~ Ni24Ti76~
cu70zr30, Cu70Ti30, V36Zr64~ V36Ti64~ Ni64Zr~6 and
Ni64 Ti36
The so-called metallic ~lasses, amorphous
metals, glassy metal~ or vitreou~ly-ri~idified metals are
amorphous metal alloys with a non-arranged ~tr~çture which
are not in thermodynamic equilibrium. Metallic gla~es
are inclined to recrystallization whenever the reaotion
temperature of the catalytic ~onver~ion lies a~ove the
1'~929~7
vitreous conversion temperature. A~ a result of
component.s of the alloy, with up to 5 atom percent, for
example, of molybdenum or tungsten, the glas~ conVersiQn
temperature can be raised sufficiently so that a
~tabillzation of the actual catalyst is achieved without
significantly influencin~ its activity. Stabilized
metallic glasses consist, for example, of Zr or Ti, Fe and
Mo, preferably with the formula (Fe~lTig)~5Mo5 or
~ FP9 1zr~)gsMo5
The catalytically-active, metallic glasses Gan
be used as such as catalysts since they often activate
themselves, partly with an enlargement of the surface.
Examples of such alloys have the formula FeglZr~ and
FeglTig.
It can, however, also be effective for various
metallic glAsses, for example Ni64Zr36 or Ni64Ti36, to
conduct catalyst activation. Catalyst activation
comprises processe~ such AS treatment with acid,
effectively dllute ac~d, pre~er~ly aqueous HN03, :In ord~r
to remove layer~ of oxide, ~hen ~ubsequent treatmçnt with
oxygen and after that treatment with hydrogen.
Consequently, the activation consists of treatment in an
oxidizing atmosphere and subsequently treatment in a
reducing atmosphere. Corresponding to the intended
purpose of use, the treatment can also be reversed.
The metallic glasses are also ~uitable as
starting product.s for catalysts without carriers. For
example, one of the phases can be converted by chemical
conversion in such a way that it açts like a carrier in
the conventional sense. As a possible di.sadvantage, there
is a smaller specific surface which results from the
various production processes.
The metallic gla~se.s can he produced in known
manner, for example, by the melt spinning process, as flat
or separated lamellae, and by the splat-cooling process,
It turned out, however, that the ribbons
obtained according to the melt-spinning process are also
easily reduced to powder at low temperAture and so can
1;29Z977
also be u~ed in powdery form. Metallis glasses or
amorphous metals, however, can also be produced directly
a.s a powder. From ribbons or foils of metallic glass or
amorphous metal, molded bodies, for example, filles of
columns, can also be produced and then activated to a
catalyst state, being used as such.
In a series of cases, for example, with Cu70Zr30
or Cu70Ti30, the catalysts from metallic glasses show
activity already at temperatures lower than the
corresponding catalysts based on crystalline starting
material. It is important that the reaction temperature
be sufficiently lower than the glass conversion
temperature of the metallic glass.
The metallic glasses of the formula ~u70Zr30 can
be ac~ivated in a hydrogen stream and then are suitable as
hydration catalysts, for example, for the hydration of
1,3-butadiene. For this reaction, it is ~dvantageous to
reduce the metallic glaffse~ wlth the formula Cu70Zr30 for
ab~lAt 2 to 8 hou~ in a hydrogen stream at 160 to 240C.
Durin~ the hydration a ratio of butadiçne to hydrogen of
2:1 to 1:1 and a temperature of 90 to 200C, preferably
9.~ to 130C, i8 maintained.
The catalytically active metallic glasses are
su~table for hydrogenation reactions, for example, the
synthesis of ammonia from hydrogçn and nitrogen, or
hydrocarbons from olefins or the hydrogenation from
nitroaromatics, for the oxidation of cyclic hydrocarbons,
such as ~oluene, and for the isomerization of
hydrocarbons, for example, methylcyclopentane.
~y way of summary, the invention involves
catalytically-active metallic glasses composed of at least
one element from Group IVA of the periodic system, for
example, Zr or Ti, and at lea~t one elçment from Group IB,
for Example, Cu, or Group VA, for example, V, or Grol~p
VIII, for example, Co, Ni, Pd or Fe. Thç mçtallic glassçs
have been self-activated or activated by an oxidative
and/or reductlve treatment. The metalllc ~lasse~ Gan bç
l~Z~7
used as catalysts, for example, for hydrogenation,
oxidation or isomerization.
The following Examples illustrate the invention
or are included for reference purposes. As used herein,
all ratios, proportions, parts and percentages are on a
weight basis unless otherwise stated herein or otherwise
obvious to one skilled in the art.
EXAMPLE 1
Synthesis of ammonia from nitrogen and hydrogen
10For the conversion, a gas of 75 percent of
hydrogen and 25 percent of nitrogen was used. The gas
mixture was free of carbon monoxide. The pressure was 9
bar. In a microcontinuous reactor, 2 g of catalyst was
inserted. The length of the catalyst bed was 20 mm, and
15the through-flow quantity was between 20 and 200 micromole
--1
sec
TABLE 1
~quilibrium turnover
nanomol~ sec~l
Startina Material .380C. 400C. 420C. Remarks
Conventional Halder- 250 450 ~00 after 2000
Top~oe catalyst hrs. not
stable
FeglZrg-crystalline 800 1400 2000 stable
after 2000
hrs .
FeglZrg-crystalline 140 260 400 stable
after 2000
hrs.
~Fegl Zr9 )gsMs
glass 180 330 S00 stable
Ni64Zr36 glass 190 340 600
A nickel-zircon catalyst produced in the
conventional manner showed no effectiveness under these
conditions. Under equilibrium turnover, the turnover is
given per contact time standardized on the surface of the
starting materials (equals average duratlon of stay of a
gas molecule in the contact volume). The Halder-Top~oe
l~Z9~77
catalyst i~ more ~ensitive vis-a-vi~ oxygen than the
Feg1Zr9 glass.
EXAMPLE 2
Synthesis of ammonia
6 The conversion was carried out in an integral
reactor made of stainless steel (40 cm long, 1.5 cm
diameter) with purified gases. Analysis of the reaction
products was done by means of an IR-gas analyzer. The
pressure was 4 bar. The total through-flow of gas was 30
to 40 mlN.min 1 with a catalyst quantity of 8 to 10 g.
The ribbons of metalliç glass or amorphous metal were
degreased and cut into piecçs of a length of 1 to 2 cm.
TABLE II
Conversion grade ~ =
~N~ 1
Starting Material Temp., C tNH3] (e q)
Feg1Zr9, amorphou6 350 0.001704
Fe91Zr9, crystalline 350 0.001309
Fe, pur~ crystalline .330 0.000144
20 Fe91Zr9, amorphous 330 0.0050~9
Fe91Zr9, crystalline 380 0.004~01
Fe, pure crystalline 450 0.00835
Fe91Zrg, crystalline 450 0.0326~
Fe24Zr7fi, amorphous 450o 0.08170
25 Fe24Zr76, amorphous 380 0.002830
Note: Ratio N2:H2 = 1:2
That alternating effects exist between the
metals in the actual effective catalyst is shown in the
comparison of the conversion figures for the ammonium
synthesis in the case of the system iron-zirconium.
Whereas pure iron does not result in an active çatalyst ~t
350C., Fe9Zr91 and Fe24Zr76 glasses form active
catalysts. Whereas Fe91Zr9 i8 more active at 400C than
35 Fe24Zr76, Fe24Zr7fi surpasses the activity of Fe~1Zr~ at
higher tem~eratures. Many highly active catalytic systems
can be obtained by way of amorphous metals.
~XAMPL~ 3
lZ~Z977
Hydrogenation of ethylene
The investigation was carried out in a
circulatory reactor, and the products were analyzed by
means of ga.s chromatography. The metallic glasses or
amorphous metals were used as strips of about 1 cm length
after they had been degreased. The reaction mixture
consisted of ethylene and hydrogen. Amorphous Ni64Zr~6
was first treated with diluted nitric acid, then treated
with oxygen and subsequently treated with hydrogen. After
this pretreatment, the material showed catalytic activity.
Feg1Zrg glass showed no activity even after the
pretreatment. Cu70Zr30 glass showed a clear enlargement
of its surface and extraordinary catalytic activity by
means of treatment with hydrogen.
TABLE III
CatalYst Reduction ActivitY
Cu70Zr30 200C very active
amorphous H~, 4 hrs. even a~ ~0C
~0 CU70zr3 200C
cry~tal~ine H2, 4 hr~
H2, 8 hrs, ---
Cu 200C.
H2, 4 hrs. ---
With amorphous Cu70Zr30, after activation at
200C, a parallel quantitative conversion was measured in
24 minutes. In the same period of time, the conversion
already was 40 percent at 80C. The difference between
amorphous and crystalline starting material showed itself
very clearly in the case of hydrogenation of ethylene by
means of Cu70Zr30. Only the amorphous starting material
resulted in an active catalyst.
EXAMPLE 4
Oxidation of toluene
The conversion was carried out with a mlcropul~e
reactor at 300C. The reactor was coated with 2 g of
amorphous V36Zr64, which previou~ly had been tr~ated with
diluted HN03. A stream of air was saturated with toluene
and was pa~ed through the micropulse reactor. After 2
lZ~Z~77
hours, the catalyst had açtivated itself; per passage,
12.5 perçent of the toluene quantity used was oxidized
into benzoic acid.
Under identical conditions, a V205 catalyst on
6 .Sio2 resulted in a conver~ion of 8.~ percent.
EXAMPLE 5
Hydrogenation of 1,3-butadiene
The reactions were carried out in a batsh-
circulation reactor and the products consisting of 1-
butene, cis-2-butene, trans-2-butene and butane were
analyzed by means of gas chromatography. Amorphous and
crystalline samples of the composltion Cu70Zr30 were
reduced at 200C for 4 hours in a stream of hydrogen.
This pretreatment caused an enlargement of the surface of
0.015 m2/g on 0.56 m2/~ with the amorphous sample, while
the 6urface of the crystalline sample remained unchanged
at O.OOB m2/g.
In order to be able to çompare the activity of
the~e sample~, catalyst ~uantitie~ were ~elected 6uch that
e~ually large curface~ were pre~en~ ln the reactor. TJnder
identical conditisn~ (T = 130C., p = 0.8 bar,
butadiene:H2 = 1:1), thece experiments clearly showed that
amorphous Cu70Zr30 was much more active than the
corresponding cry6talline sample.
TABLE IV
0.12 g of amorphous 8.0 ~ of crystalline
t(min)conversion, ~ercent conversion, ~ercent
4.59 0.0
13.04 o,o
~o 16.76 0.0
130 23.00 o.g
130 2~.00 1.1
The selectlvlty a~ to butene wa~ more closely
investigated with the amorphous sample. In the ca~e of 90
percent conversion, the selectivity w~s 75 percent at
130C and 96 percent at 95C.
lZ9Z977
EXAMPLE ~
';elective hydrogenation of butadiene
Dienes, especially 1,3-butadiene, cause
cleactivation of the catalyst in the case of
hydroformylation and form polymers in cracking operations.
Therefore, they should be removed from olefins.
According to Example 5, 4 g of amorphous
Cu70Zr30 was used as catalyst. The hydrogenation of the
mixture with the composition: ~3 percent of 1-butene, 24
percent of cis-2-butene and 3 percent of 1~3-butadiene,
was examined at various temperatures. At temperatures
higher than 90C, olefins were hydrated and large
quantities of ~utane developed. At 75C butadiene was
hydrated selectively and the product distribution
15 consisted of~ 1.63 percent of butane, 1.35 percent of
trans-2-butene, 22.6 percent of cis-2-butene, 74.41
percent of 1-butene and 0.0 percent of butadlene, after a
reaction time of ~0 minutes. The hydro~en concentration
at the ~ame time was 2 to 4 t~.me~ greater than the
butadiene concentration. In thi~ area, the hydrogen
concentration had no greater influence on the selectivity.
The selective hydrogenation of butadiene in the mixture of
ethylene and butadiene also took place at lower
temperatures. The reaction temperature of 7SC made
possible the hydrogenation of butadiene with 93 percent
selectivity on butene; ethylene was not hydrated at all.
Higher temperatures however also cause the hydrogenation
of ethylene.
