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The activity of cobalt-zirconia and cobalt-nickel-zirconia preparations in the Fischer-Tropsch reaction
349
Applied Catalysis, 8 (1983) 349-358 ElsevierSciencePublishersB.V.,Amsterdam - Printed in The Netherlands
THE ACTIVITY
OF COBALT-ZIRCONIA
IN THE FISCHER-TROPSCH L.A. BRUCE,
AND COBALT-NICKEL-ZIRCONIA
G.J. HOPE and J.F. MATHEWSly2
CSIRO, Division
of Materials
Science,
Victoria, 3052, Australia. 1 Present address: Department
University
of Chemical
Saskatchewan,
Saskatoon,
2Work carried
out while a visiting
(Received
PREPARATIONS
REACTION
Saskatchewan
21 June 1983, accepted
of Melbourne,
Engineering,
Parkville,
University
of
S7N OWO, Canada.
scientist
18 August
1979-1980.
1983)
ABSTRACT The activity
and selectivity
of cobalt-(nickel)-zirconia that catalysts formulations of cobalt
in the carbon monoxide/hydrogen
catalysts
of comparable
activity
and selectivity
of cobalt-kieselguhr-additives
onto a co-precipitate
reaction
It is shown
have been studied.
with traditional
are obtained
by impregnation
of 3 wt % nickel-zirconia.
The product
is then over 60 wt % C5+ and rich in 1-enes at the C4, C5 and C6 levels. Other preparative
methods
can give comparable
activity,
ivity to C5+ is less than 30 wt %, and 2-enes
but the select-
predominate
at the C4, C5
and C6 levels.
INTRODUCTION Nickel-zirconia
catalysts
the Fischer-Tropsch
reaction,
stable solid solution on most common selectivity olefins zirconia
obtained
supports
is moved
show unusual activity especially
by co-precipitation
is a methanation
catalyst,
to higher hydrocarbons,
in the product.
highly unsaturated include combinations
[l].
with zirconia
hydrocarbon
product
a similar
supports [3,4].
nickel the of
with
study to that
is known to give a
The scope was extended
of nickel and cobalt with zirconia
various ways.
0166-9834/83/$03.00
Whereas
Cobalt oxide also forms a solid solution
since cobalt on the comnon
in
via the meta-
with a high proportion
[2], and this has led us to undertake
with nickel,
and selectivity
when prepared
0 1983 Elsevier Science Publishen, B.V.
prepared
in
to
350 EXPERIMENTAL Catalyst Materials The method for catalyst
and Pre-treatment
of preparation
preparation
similar to those described of zirconia,
at 373 K, after which
flowing hydrogen [l].
Analyses
as the source
as the sources
sufficient
sample for testing and characterization
argon finally at 640 K, followed
by reduction
for nickel and cobalt were by atomic adsorption
Catalyst Testing
mixture
in
of carbon monoxide by Commonwealth
and hydrogen Industrial
in
spectro-
(40.8 mol%
Gases.
and Characterization
Study of the catalyst pressure
activity
and selectivity
with the stainless
equipment
described
hourly space velocity
was in the range 3000-15,000
the C2 and C3 fractions Poropac QS column.
into
Details
was 0.05-0.10
g.
of the total reactant
Product analyses,
made on a 6m x 3mm OV-101 column.
and
Bed
of internal diameter
h -I, to keep conversion
less than 8%.
micro-reactor,
lines and sample valves
of the catalyst
lengths were in the range 5-10 mn in a reactor 5 Inn. The volumetric
was made at 103 kPa
steel down-flow
in [1]: transfer
The weight
were heated to 373 K.
to hydrocarbons
of
drying of all samples was in an air oven
CO, 59.2 mol% H2) was supplied
associated
were
at 640 K, using the flow rates and time regimens
An analysed
operating
and the techniques
nitrate
and nickel nitrate
Preliminary
was dried in flowing
support,
and by co-precipitation
in [1] using zirconyl
and cobalt nitrate
these components.
scopy.
of the zirconia
by impregnation
of carbon monoxide
Cl through
Special analyses
gas
C12, were
for the breakdown
of
'-ene' and '-ane' were made on a 2m x 3nnn of catalyst
compositions
are given in a
later section. Hydrogen
adsorption
had been outgassed
measurements
were made at 295 K at hydrogen adsorption
pressures
(H/M(,)) was estimated
linear and nearly horizontal Some temperature the same procedure
were made on reduced
at 470 K for about 17 h
as described
reduction
to a linear
to zero pressure
as the temperature
increase
of the
isotherm.
profiles were obtained
using
in [1], i.e. the uptake of hydrogen
flowing 3 mol% H2 in N2 was monitored sample was subject
up to about 27 kPa, and monolayer
by extrapolation
part of the adsorption
programmed
samples which
: adsorption measurements
in temperature
from
of the test
to a maximum
of
850 K.
RESULTS Throughout number
(c.f.
this paper catalysts
are identified
Table 1 for compositions).
The prefix
by prefix and 12 denotes
preparation
361
by impregnation
onto pure zirconia,
itation with zirconia
as described
Activity
co-precipitate
Activity
preparation
(3.1 wt % nickel)
by impregnation
which was prepared
Distribution
data for a range of catalysts
energy values were obtained
the temperature
range 453-553
K.
in terms of the turnover number of exposed
number,
The table also records
in Table 1. over
activities
at
per unit mass of Co t Ni, and
the latter being computed
metal atoms determined
In all cases the activity
are summarized
from rate data accumulated
523 K in terms of the rate of CO reaction
data.
to co-precip-
in [l].
and Product
Activation
preparation
and IZN denotes
hydrogel,
onto a nickel-zirconia
CZ denotes
from the hydrogen
levels remained
constant
using the monolayer for at least 8
hours on stream at a given temperature. The impregnation precipitation
of cobalt on pure zirconia
of a small amount
The relatively
inactive
catalysts.
resulted
in a catalyst
from CZ-1. impregnation whilst
impregnations
series)
produced
some of the catalysts
prepared
in this study.
among the selectivity
data presented
(a)
with respect
An increase
shifts the product relative
(b)
distribution
on other
The impregnation
Co-precipitation
1)
Comparisons
in Table 2 lead to the following
amount strongly
toward
of higher
hydrocarbon
of cobalt-to-nickel
products.
(the IZN-series)
to the C5+ hydrocarbons.
is consistent
higher hydrocarbons.
This
with literature
of cobalt with zirconia
is greater
does not
IZ-2 gives the same
as IZN-0.
of large amounts
amount of cobalt
IZ-1, CZ-1 and
too low (c.f. Table
of cobalt with nickel on pure zirconia
amount of C5+ hydrocarbons
(c)
Catalysts
for
supports.
the selectivity
the production
base (IZN-
data at 523 K.
to the proportion
status of cobalt and nickel
observations
modify
distribution
in the relative
activity
at 523 K (H2/CO=1.45)
(and conversions)
product
in the
activities.
distributions
activities
and activity
of moderate
co-precipitated
of the highest
to produce meaningful
observations
structure
(IZ-2) gave a catalyst
Table 2 shows the product
in CZ-2
large amount of nickel
on a nickel-zirconia
catalysts
IZ-3 all exhibited
different
of a relatively
on pure zirconia
(CZ-1) give very
large amount of cobalt
with significantly
The addition
(IZ-1) and the co-
of cobalt with zirconia
(CZ-2) does not lead to
of C5+ hydrocarbons
even though the
than that in the two major
C5+ producers,
IZN-2 and IZN-3. Assessment
of selectivity
in the range C, through
and activity
Cl2 because
was restricted
experimental
artefacts
to products led to
352 TABLE 1 Activity
of cobalt-zirconia
Catalyst
Composition/
Rate at 523 K/ NC0 at 523 K/ -1 -1 urn01 co s g s-'x103
H2 monolayer
wt %
uptake/unol Ni
Co
catalystsa
(CotNi)
g-' (Co+Ni)
kJ mO1
0.4
10
-1
61
IZ-1
3.5
0
CZ-1
2.8
0
CZ-2
9.8
0
IZ-2
2.7
8.0
186
4.8
13
106
IZN-1
2.5
8.2
266
13.0
25
102
0.4
10
92
IZ-3
7.3
20
Eact/
-
1.8
19.8
0.1
118
7.0
109
IZN-2
7.8
4.7
207
14.0
33
102
IZN-3
7.0
2.9
216
31.0
72
119
IZN-Ob
0
3.1
526
57.0
53
102
a:
Reaction
b:
cobalt
conditions:
103 kPa, Hz/CO = 1.45.
free nickel-zirconia
used as support
co-precipitate
for cobalt and nickel
(3.1 wt % nickel)
impregnation
[1], also
in catalysts
IZN-1,
IZN-2, IZN-3.
TABLE 2 Selectivity
of Zirconia
Catalyst
Catalystsa
Co/Ni
Selectivity,
wt.% C,
Conversion
Cl
c2
C3
C4
C5t
IZN-0
0
24
17
27
14
18
8
IZN-1
0.30
22
12
21
10
35
4
IZN-2
1.7
15
5
11
10
60
5
IZN-3
2.4
11
6
10
10
63
5
IZ-2
0.34
33
17
22
10
18
3.5
30
6
18
14
32
6
cz-2
a:
m
Reaction
conditions:
irreproducibility therefore
at higher carbon numbers.
represent
carbon number
523 K, 103 kPa, H2/C0 = 1.45.
a high estimate
and a low estimate
down of the C5-Cl2 Table 3, reveals
region
the range C,. through
C12.
of overall
for catalysts
a trend toward
The figures
presented
of the true selectivity activity.
IZN-1,
increasing
above
at a particular
A detailed
break-
IZN-2 and IZN-3, shown in
weight
per cent of product
in
353
TABLE 3 Detail of C5+ Analyses
over
IZN-Series
Catalysts
Selectivity,
Catalyst
Wt % Cn Cl0
Cl1
c12
2.1
3.7
5.1
8.2
4.8
6.5
9.2
9.9
5.6
7.0
9.6
13.9
'5
'6
'7
'8
'9
IZN-1
5.7
3.4
4.5
2.6
IZN-2
9.2
9.0
6.2
5.4
IZN-3
8.5
7.2
5.8
5.3
In addition analyses
to the overall
of olefin
and isomer content
the chromatographic The P-ene content
selectivity
results,
IZ-2 and
a product which
every case, the balance
at C2 through
and iso- pentane
3- Me pentane occur along with n-hexane, one third of the alkane concerning
fraction.
these details
number,
C6 are contained
IZN-0includes
is absent
in
in Table 4.
a large proportion
from all other
at C4 and C5 is virtually
only traces of iso- butane
with carbon
and some of these are presented
at C5 over
of 2-Me-but-2-ene,
changes
streams.
In
all the normal alkane;
occur.
At C6, some 2- and
and usually
constitute
about
A number of points may be made
of the selectivity.
TABLE 4a Olefin
Fraction
at C2 to C6 over Zirconia
Catalyst
IZ-2
Conversion
IX #
3.5
6
IZN-1
IZN-2
IZN-3
8
4
5
5
-ene
n.m.b
0.80
0.10
0.26
0.67
0.67
3
-ene
n.m. b
0.95
n.m. b
0.78
0.98
0.96
0.30
0.33
0.33
0.48
0.88
4
I-ene
0.17
E-ene 1-ene
0.48 0.01
0.57 0.09
0.46 0.11
0.33 0.25
0.25 0.49
0.12 0.51
5 2-ene I-ene
0.59 0
E-ene
a b
I
IZN-0
2
F5 2 9
%
cz-2
Catalysts
0.14
0.30
T = 523 K, H2/C0 = 1.45. n.m. = not measured.
0.67
0.65 n.m. b
0.44
n.m.b
0.45 ~0
0.31
0.38 0.23
0.34
0.25
0.37 0.36
354 (a)
the reaction
products
(b)
the higher hydrogenation is most clearly
activity
which,
in turn, is somewhat
differences
ratios
In this respect,
Catalyst (i)
favour
the correlation
but with the proportion
is not
of products
IZN-2 and IZN-3, which are the
the production
of 1-enes, whereas
the
Characterization
As prepared,
Microscopy
all of the zirconia
X-rays, with the exception separated
was detected
based catalysts
of CZ-2, which
from the solid solution. against
the cubic and tetragonal
contained
a high background
than 20 nm, according
to calculations
of (1ll)f.c.c.
of the transition
from amorphous
peak was present
for catalysts
peak always
equation
lay between
consisting
those
No metal
IZ-1, CZ-1 or IZN-3, but for IZ-2 and IZ-3
to 4 nm grains was present.
CZ-2, IZN-2 and IZN-1, the metal ution of grains,
of
to a grain size less
Co and (111)Ni; h.c.p. Co was never present.
a small peak corresponding
material;
because
from the Debye-Scherrer metal
to
phase
some crystalline
forms could not be differentiated
lines, which corresponded
The position
were amorphous
some @-COG
After reduction,
the width of detected
[5].
in the 1-ene/Z-ene
favour 2-ene production.
X-ray and Electron
zirconia
over
and -3,
are less clear at higher
differences
in the C5+ range; the catalysts
other catalysts
to cobalt content
less than that over CZ-2.
with nickel content,
major C5+ producers,
the olefin
lower than over that over IZN-2
but significant
become evident.
obviously
of nickel as compared
in total olefin content
carbon number,
in every case.
seen at the C2 level, where
and IZN-1 is markedly
IZN-0
(c)
are highly olefinic
peak was typical
of a narrow
In the case of
of a bimodal
distrib-
peak, due to some large grains,
sitting on a very broad base from very small ones. It was not possible electron
microscopy
distinguishing zirconia,
to obtain
studies,
a particle
because of the problem discussed
small crystals
of metal
from equally
which also gives high contrast.
in the reactor
exhibited
size distribution
no obvious
in [1], of
small crystals
Catalysts
changes;
from
examined
in particular,
of
after use
deposition
of
carbon was never observed.
(ii)
Temperature
Programned
Study of the catalysts some insight 'support'. reduction
Reduction
into the function Preparations
(TPR)
by temperature of IZN-0,
on pure zirconia
at 695 K, and showed a maximum
total reduction
of cobalt and nickel
programmed
the nickel
reduction
by impregnation in hydrogen
to zero valency
gives
co-precipitate,
as
commenced
uptake
at 795 K;
was achieved
at the
355 end of the program. content, maximum
As regards
the co-precipitates,
CZ-1, only began to show reduction before
effected;
that of high cobalt
reached,
reduction of cobalt
although
co-precipitate
of reduction
was
CZ-2, showed a small maximum fraction),
reduction
was achieved. lowered
to 645 K, and the maximum Kelvin degrees
By contrast,
the temperature
relative
was
impreg-
of
in hydrogen
uptake
to those observed
and total reduction
onto pure zirconia,
at
of the
began at 765 K, but again no major maximum
745 K, i.e. both by fifty impregnation
content,
of the B-Co(OH)2
about 70% reduction
nation onto the nickel initiation
no
the end of the ramp and no more than 10% reduction
630 K (probably major fraction
that of low cobalt
at 795 K, displayed
of cobalt
to for
and nickel
to zero valency was obtained.
DISCUSSION There are two major of a catalyst
results
to be considered:
of cobalt-nickel-zirconia
excess of 60 wt.% to C5+ hydrocarbons, obtained
by using a nickel-zirconia
zirconia
as support
and
of cobalt
studied,
only
co-precipitate,
them from the others.
witness,
reduction
high cobalt
temperature
final factor which defines
catalyst
studied
isation activity inferred
applies
by them, the l- olefins
increases
It is not initial
witness
CZ-2.
The at
is thus implied
2- olefins
to the present
are primary
Co-kieselguhr products,
on the support.
and Although
we have some evidence
with space velocity,
for the present
over
differ-
is high 1-ene, as measured
reaction
this point in detail,
to be deleterious
P-Me-but-P-ene
IZN-1.
that on the traditional
catalysts.
that the
indicating
a
From Table 4, high isomer-
for all but IZN-2 and IZN-3, and is
to chain growth.
Pichler et al [4] also report to produce
factors content,
and lowered
to the TPR results),
the difference
IZN-0,a
(Table 4).
of 1-olefins
situation
what
witness
high activity
arise by secondary
we have not studied
similar
content,
et al [4] report
isomeric olefins
proportion
to establish
onto
stream containing
It is not only high cobalt
(according
C4, C5 and C6 levels Pichler
respectively
give a product
It is not only high activity,
CZ-2.
even entirely
rather than pure
catalysts.
IZN-2and IZN-3, produced by
over 60 wt.% C5+, and it is of interest entiate
in
(ii) the higher activities
and cobalt + nickel
3 wt.% nickel-zirconia
(i) the production
shows selectivity
co-precipitate
for the cobalt-nickel
Among the catalysts impregnation
which
increases catalysts
IZ-2 and
that isomerisation
of the double
bond
with chain length, a result which also (Table 4).
The presence
of substantial
IZN-0 indicates that skeletal isomerisation
356 has occured
over these supports.
sites of much higher
strength
Results on the activity nickel-zirconia are included
This requires
than that needed for double and selectivity
co-precipitate,
in the present
lowering
temperature
throughout
of even C5+
IZN-3 is as
The function
of the impregnated
of IZN-0
cobalt
is a matter
in
is obvious
for conjecture.
first gives small nuclei of nickel uniformly
the sample, which
atomic hydrogen
[l], but
Impregnation
IZN-1 through
but the mode of action
We suspect that reduction
bond shift.
the 3 wt.%
C2 and C3, and increased
None of the preparations
the reduction
of acid
elsewhere
paper for comparison.
active per g of cobalt + nickel as IZN-0.
from the TPR results,
of IZN-0,
have been reported
a small amount of Co, in IZN-1, lowered substantially.
the presence
to facilitate
then operate reduction
by a spill-over
mechanism
of
of cobalt.
TABLE 5 Activity
and Selectivity
Catalyst
of Cobalt Catalysts
lmole CO
NCO see-'x103
sec-lg-lCo
E
Selectivity,
kJ mole-'
Cl
C2
C3
wt.% C4
Ref
C5+
2wt.X CO/A~~O~~
0.51
5.1
-
60
14
19
8
0
6
', H2/CO=3
0.85
8.6
112
64
11
15
6
4
6
10
19
7
65
8
21.4 36
95
46
9.9
-
139
5
", H2/CO=3
7
not given
-
78 131
4wt.% Co/Si02a
12
13
1OOCo 1OCu 18Th02 200 kieselguhrasb
a b
extrapolated excluding
to H2/C0 = 1.45, T = 523 K.
C02; selectivity
Some values are assembled
for activity
to the conditions
e.g.
and selectivity
as used by us. [6] are similar
for cobalt on other supports
are reported
of 4 wt.% Co/Si02, for the IZN- series
However,
the activities
obtained
by impregnation
selectivity
Detail of the selectivity to be absent
catalysts,
where necessary,
The values of activity to those obtained
IZ-1, -2 and -3.
strongly toward methane. as olefins
at T = 523 + 30 K, H2/C0 = 3.
in Table 5; these have been extrapolated,
2 wt.% Co/A1203 zirconia,
30
over alumina
is
is also different,
from the C4 fraction.
reported
for onto
In the case
[7] are now more like those
but the selectivity
to methane
is still
351
high, and CS+ production
is still low; the C4 fraction
Dent and Lin [8] have studied a view to optimising commercial
C2-C4 production,
formulation
reveal activity
a variety
Results
[2].
and selectivity
Lin do not detail
the C4 analysis
residue
but Pichler,
them non-Schulz-Flory-Anderson behaviour
(S.F.A.)
from the S.F.A. distribution
Cl and C2, isconmonly
reported.
catalysts
and Suhl have recently
hydrocarbon
However,
at high carbon
made a systematic
might be disturbed if readsorbed
and report
olefins
chains above a certain
to explain
are subject
'pile-up'
the observations,
to carbonium
based catalysts,
in the direction
that normal
to cracking
or if [9].
distribution
to account
than
for the deviations
if l- or 2- olefins and subsequent
can be of, say,
cracking
at
they may give rise to a
to catalysts
Fischer-Tropsch
of a high CS+ fraction
in the co-precipitate
leading
since
the S.F.A.
differences
in chain growth,
a much broader
ion formation
and nickel onto a nickel-zirconia nickel
Novak, Madon
that significant
participate
seen
in the Clo+ region.
It can be concluded modified
deviations
On the other hand, the second mechanism
acid sites on the zirconia minor
in distribution. at low carbon number,
length are subject
is to produce
in this case.
C12, which clearly
number are not.
and seems unlikely
014
[4]
81% 1-ene,
study of ways in which
the S.F.A. distribution,
applied
and Elstner
the additional
The effect of the former
observed
Dent and
-3 each shows an increasing
in the range C,. through
Deviant
can be obtained
Schultz
at 473 K, have reported
renders
distribution
from a well-tried
to IZN-2 and IZN-3.
data for IZN-1 through
per cent of product
with the present
with
n-butane.
The selectivity weight
starting
is 25% olefin.
based catalysts,
on the latter shown in Table 5
similar
over 100 Co 18 Th02 100 kieselguhr 3% 2-enes,
of cobalt
by impregnating
co-precipitate.
promotes
The presence
the reduction
with high activity
selectivity
of cobalt
as well as unusual
can be cobalt of
thus
selectivity.
ACKNOWLEDGEMENTS We gratefully National
acknowledge
Energy Research,
partial
Development
financial
We also wish to thank Miss 8. Terrell, Jaeger,
M. Jestrimski
ital aspects
of this work by Council.
Dr. K. Foger and Messrs.
for their participation
advice on presentation
given to us by Dr. J.R. Anderson
and preparation
H.
in experi-
of the work.
The constructive manuscript
and R. Sherwood
support
and Demonstration
of the
is very much appreciated.
358
REFERENCES l Bruce, L.A. and Mathews, J.F., Applied Catalysis, 4, 353 (1982). 2 St~cker, H.J., Annales de Chimie 13s. 5, 1459 (1960). 3 Anderson, R.B., "Catalysis", Vol. IV, ed. Emmett, P.H., Reinhold (1956). 4 Pichler, H., Schulz, H. and Elstner, it., Brennstoff-Chemie 48, 78 (1967). 5 Klug, H.P. and Alexander, L.E., 'X-Ray Diffraction Procedures', J. Wiley and Sons Inc., New York, 1954, p.491. 6 Vannice, M.A., J. Catalysis, 37, 449 (1975). 7 Vannice, M.A., J. Catalysis, 50, 228 (1977). 8 Dent, A.L. and Lin, M., Advances in Chemistry Series, Amer. Chem. Soc., 178 (1979) p.47. 9 Novak, S., Madon, R.J. and Suhl, H., J. Chem. Phys., 74, 6083 (1981); J. Catalysis, 77, 141 (1982).
Applied Catalysis, 8 (1983) 349-358 ElsevierSciencePublishersB.V.,Amsterdam - Printed in The Netherlands
THE ACTIVITY
OF COBALT-ZIRCONIA
IN THE FISCHER-TROPSCH L.A. BRUCE,
AND COBALT-NICKEL-ZIRCONIA
G.J. HOPE and J.F. MATHEWSly2
CSIRO, Division
of Materials
Science,
Victoria, 3052, Australia. 1 Present address: Department
University
of Chemical
Saskatchewan,
Saskatoon,
2Work carried
out while a visiting
(Received
PREPARATIONS
REACTION
Saskatchewan
21 June 1983, accepted
of Melbourne,
Engineering,
Parkville,
University
of
S7N OWO, Canada.
scientist
18 August
1979-1980.
1983)
ABSTRACT The activity
and selectivity
of cobalt-(nickel)-zirconia that catalysts formulations of cobalt
in the carbon monoxide/hydrogen
catalysts
of comparable
activity
and selectivity
of cobalt-kieselguhr-additives
onto a co-precipitate
reaction
It is shown
have been studied.
with traditional
are obtained
by impregnation
of 3 wt % nickel-zirconia.
The product
is then over 60 wt % C5+ and rich in 1-enes at the C4, C5 and C6 levels. Other preparative
methods
can give comparable
activity,
ivity to C5+ is less than 30 wt %, and 2-enes
but the select-
predominate
at the C4, C5
and C6 levels.
INTRODUCTION Nickel-zirconia
catalysts
the Fischer-Tropsch
reaction,
stable solid solution on most common selectivity olefins zirconia
obtained
supports
is moved
show unusual activity especially
by co-precipitation
is a methanation
catalyst,
to higher hydrocarbons,
in the product.
highly unsaturated include combinations
[l].
with zirconia
hydrocarbon
product
a similar
supports [3,4].
nickel the of
with
study to that
is known to give a
The scope was extended
of nickel and cobalt with zirconia
various ways.
0166-9834/83/$03.00
Whereas
Cobalt oxide also forms a solid solution
since cobalt on the comnon
in
via the meta-
with a high proportion
[2], and this has led us to undertake
with nickel,
and selectivity
when prepared
0 1983 Elsevier Science Publishen, B.V.
prepared
in
to
350 EXPERIMENTAL Catalyst Materials The method for catalyst
and Pre-treatment
of preparation
preparation
similar to those described of zirconia,
at 373 K, after which
flowing hydrogen [l].
Analyses
as the source
as the sources
sufficient
sample for testing and characterization
argon finally at 640 K, followed
by reduction
for nickel and cobalt were by atomic adsorption
Catalyst Testing
mixture
in
of carbon monoxide by Commonwealth
and hydrogen Industrial
in
spectro-
(40.8 mol%
Gases.
and Characterization
Study of the catalyst pressure
activity
and selectivity
with the stainless
equipment
described
hourly space velocity
was in the range 3000-15,000
the C2 and C3 fractions Poropac QS column.
into
Details
was 0.05-0.10
g.
of the total reactant
Product analyses,
made on a 6m x 3mm OV-101 column.
and
Bed
of internal diameter
h -I, to keep conversion
less than 8%.
micro-reactor,
lines and sample valves
of the catalyst
lengths were in the range 5-10 mn in a reactor 5 Inn. The volumetric
was made at 103 kPa
steel down-flow
in [1]: transfer
The weight
were heated to 373 K.
to hydrocarbons
of
drying of all samples was in an air oven
CO, 59.2 mol% H2) was supplied
associated
were
at 640 K, using the flow rates and time regimens
An analysed
operating
and the techniques
nitrate
and nickel nitrate
Preliminary
was dried in flowing
support,
and by co-precipitation
in [1] using zirconyl
and cobalt nitrate
these components.
scopy.
of the zirconia
by impregnation
of carbon monoxide
Cl through
Special analyses
gas
C12, were
for the breakdown
of
'-ene' and '-ane' were made on a 2m x 3nnn of catalyst
compositions
are given in a
later section. Hydrogen
adsorption
had been outgassed
measurements
were made at 295 K at hydrogen adsorption
pressures
(H/M(,)) was estimated
linear and nearly horizontal Some temperature the same procedure
were made on reduced
at 470 K for about 17 h
as described
reduction
to a linear
to zero pressure
as the temperature
increase
of the
isotherm.
profiles were obtained
using
in [1], i.e. the uptake of hydrogen
flowing 3 mol% H2 in N2 was monitored sample was subject
up to about 27 kPa, and monolayer
by extrapolation
part of the adsorption
programmed
samples which
: adsorption measurements
in temperature
from
of the test
to a maximum
of
850 K.
RESULTS Throughout number
(c.f.
this paper catalysts
are identified
Table 1 for compositions).
The prefix
by prefix and 12 denotes
preparation
361
by impregnation
onto pure zirconia,
itation with zirconia
as described
Activity
co-precipitate
Activity
preparation
(3.1 wt % nickel)
by impregnation
which was prepared
Distribution
data for a range of catalysts
energy values were obtained
the temperature
range 453-553
K.
in terms of the turnover number of exposed
number,
The table also records
in Table 1. over
activities
at
per unit mass of Co t Ni, and
the latter being computed
metal atoms determined
In all cases the activity
are summarized
from rate data accumulated
523 K in terms of the rate of CO reaction
data.
to co-precip-
in [l].
and Product
Activation
preparation
and IZN denotes
hydrogel,
onto a nickel-zirconia
CZ denotes
from the hydrogen
levels remained
constant
using the monolayer for at least 8
hours on stream at a given temperature. The impregnation precipitation
of cobalt on pure zirconia
of a small amount
The relatively
inactive
catalysts.
resulted
in a catalyst
from CZ-1. impregnation whilst
impregnations
series)
produced
some of the catalysts
prepared
in this study.
among the selectivity
data presented
(a)
with respect
An increase
shifts the product relative
(b)
distribution
on other
The impregnation
Co-precipitation
1)
Comparisons
in Table 2 lead to the following
amount strongly
toward
of higher
hydrocarbon
of cobalt-to-nickel
products.
(the IZN-series)
to the C5+ hydrocarbons.
is consistent
higher hydrocarbons.
This
with literature
of cobalt with zirconia
is greater
does not
IZ-2 gives the same
as IZN-0.
of large amounts
amount of cobalt
IZ-1, CZ-1 and
too low (c.f. Table
of cobalt with nickel on pure zirconia
amount of C5+ hydrocarbons
(c)
Catalysts
for
supports.
the selectivity
the production
base (IZN-
data at 523 K.
to the proportion
status of cobalt and nickel
observations
modify
distribution
in the relative
activity
at 523 K (H2/CO=1.45)
(and conversions)
product
in the
activities.
distributions
activities
and activity
of moderate
co-precipitated
of the highest
to produce meaningful
observations
structure
(IZ-2) gave a catalyst
Table 2 shows the product
in CZ-2
large amount of nickel
on a nickel-zirconia
catalysts
IZ-3 all exhibited
different
of a relatively
on pure zirconia
(CZ-1) give very
large amount of cobalt
with significantly
The addition
(IZ-1) and the co-
of cobalt with zirconia
(CZ-2) does not lead to
of C5+ hydrocarbons
even though the
than that in the two major
C5+ producers,
IZN-2 and IZN-3. Assessment
of selectivity
in the range C, through
and activity
Cl2 because
was restricted
experimental
artefacts
to products led to
352 TABLE 1 Activity
of cobalt-zirconia
Catalyst
Composition/
Rate at 523 K/ NC0 at 523 K/ -1 -1 urn01 co s g s-'x103
H2 monolayer
wt %
uptake/unol Ni
Co
catalystsa
(CotNi)
g-' (Co+Ni)
kJ mO1
0.4
10
-1
61
IZ-1
3.5
0
CZ-1
2.8
0
CZ-2
9.8
0
IZ-2
2.7
8.0
186
4.8
13
106
IZN-1
2.5
8.2
266
13.0
25
102
0.4
10
92
IZ-3
7.3
20
Eact/
-
1.8
19.8
0.1
118
7.0
109
IZN-2
7.8
4.7
207
14.0
33
102
IZN-3
7.0
2.9
216
31.0
72
119
IZN-Ob
0
3.1
526
57.0
53
102
a:
Reaction
b:
cobalt
conditions:
103 kPa, Hz/CO = 1.45.
free nickel-zirconia
used as support
co-precipitate
for cobalt and nickel
(3.1 wt % nickel)
impregnation
[1], also
in catalysts
IZN-1,
IZN-2, IZN-3.
TABLE 2 Selectivity
of Zirconia
Catalyst
Catalystsa
Co/Ni
Selectivity,
wt.% C,
Conversion
Cl
c2
C3
C4
C5t
IZN-0
0
24
17
27
14
18
8
IZN-1
0.30
22
12
21
10
35
4
IZN-2
1.7
15
5
11
10
60
5
IZN-3
2.4
11
6
10
10
63
5
IZ-2
0.34
33
17
22
10
18
3.5
30
6
18
14
32
6
cz-2
a:
m
Reaction
conditions:
irreproducibility therefore
at higher carbon numbers.
represent
carbon number
523 K, 103 kPa, H2/C0 = 1.45.
a high estimate
and a low estimate
down of the C5-Cl2 Table 3, reveals
region
the range C,. through
C12.
of overall
for catalysts
a trend toward
The figures
presented
of the true selectivity activity.
IZN-1,
increasing
above
at a particular
A detailed
break-
IZN-2 and IZN-3, shown in
weight
per cent of product
in
353
TABLE 3 Detail of C5+ Analyses
over
IZN-Series
Catalysts
Selectivity,
Catalyst
Wt % Cn Cl0
Cl1
c12
2.1
3.7
5.1
8.2
4.8
6.5
9.2
9.9
5.6
7.0
9.6
13.9
'5
'6
'7
'8
'9
IZN-1
5.7
3.4
4.5
2.6
IZN-2
9.2
9.0
6.2
5.4
IZN-3
8.5
7.2
5.8
5.3
In addition analyses
to the overall
of olefin
and isomer content
the chromatographic The P-ene content
selectivity
results,
IZ-2 and
a product which
every case, the balance
at C2 through
and iso- pentane
3- Me pentane occur along with n-hexane, one third of the alkane concerning
fraction.
these details
number,
C6 are contained
IZN-0includes
is absent
in
in Table 4.
a large proportion
from all other
at C4 and C5 is virtually
only traces of iso- butane
with carbon
and some of these are presented
at C5 over
of 2-Me-but-2-ene,
changes
streams.
In
all the normal alkane;
occur.
At C6, some 2- and
and usually
constitute
about
A number of points may be made
of the selectivity.
TABLE 4a Olefin
Fraction
at C2 to C6 over Zirconia
Catalyst
IZ-2
Conversion
IX #
3.5
6
IZN-1
IZN-2
IZN-3
8
4
5
5
-ene
n.m.b
0.80
0.10
0.26
0.67
0.67
3
-ene
n.m. b
0.95
n.m. b
0.78
0.98
0.96
0.30
0.33
0.33
0.48
0.88
4
I-ene
0.17
E-ene 1-ene
0.48 0.01
0.57 0.09
0.46 0.11
0.33 0.25
0.25 0.49
0.12 0.51
5 2-ene I-ene
0.59 0
E-ene
a b
I
IZN-0
2
F5 2 9
%
cz-2
Catalysts
0.14
0.30
T = 523 K, H2/C0 = 1.45. n.m. = not measured.
0.67
0.65 n.m. b
0.44
n.m.b
0.45 ~0
0.31
0.38 0.23
0.34
0.25
0.37 0.36
354 (a)
the reaction
products
(b)
the higher hydrogenation is most clearly
activity
which,
in turn, is somewhat
differences
ratios
In this respect,
Catalyst (i)
favour
the correlation
but with the proportion
is not
of products
IZN-2 and IZN-3, which are the
the production
of 1-enes, whereas
the
Characterization
As prepared,
Microscopy
all of the zirconia
X-rays, with the exception separated
was detected
based catalysts
of CZ-2, which
from the solid solution. against
the cubic and tetragonal
contained
a high background
than 20 nm, according
to calculations
of (1ll)f.c.c.
of the transition
from amorphous
peak was present
for catalysts
peak always
equation
lay between
consisting
those
No metal
IZ-1, CZ-1 or IZN-3, but for IZ-2 and IZ-3
to 4 nm grains was present.
CZ-2, IZN-2 and IZN-1, the metal ution of grains,
of
to a grain size less
Co and (111)Ni; h.c.p. Co was never present.
a small peak corresponding
material;
because
from the Debye-Scherrer metal
to
phase
some crystalline
forms could not be differentiated
lines, which corresponded
The position
were amorphous
some @-COG
After reduction,
the width of detected
[5].
in the 1-ene/Z-ene
favour 2-ene production.
X-ray and Electron
zirconia
over
and -3,
are less clear at higher
differences
in the C5+ range; the catalysts
other catalysts
to cobalt content
less than that over CZ-2.
with nickel content,
major C5+ producers,
the olefin
lower than over that over IZN-2
but significant
become evident.
obviously
of nickel as compared
in total olefin content
carbon number,
in every case.
seen at the C2 level, where
and IZN-1 is markedly
IZN-0
(c)
are highly olefinic
peak was typical
of a narrow
In the case of
of a bimodal
distrib-
peak, due to some large grains,
sitting on a very broad base from very small ones. It was not possible electron
microscopy
distinguishing zirconia,
to obtain
studies,
a particle
because of the problem discussed
small crystals
of metal
from equally
which also gives high contrast.
in the reactor
exhibited
size distribution
no obvious
in [1], of
small crystals
Catalysts
changes;
from
examined
in particular,
of
after use
deposition
of
carbon was never observed.
(ii)
Temperature
Programned
Study of the catalysts some insight 'support'. reduction
Reduction
into the function Preparations
(TPR)
by temperature of IZN-0,
on pure zirconia
at 695 K, and showed a maximum
total reduction
of cobalt and nickel
programmed
the nickel
reduction
by impregnation in hydrogen
to zero valency
gives
co-precipitate,
as
commenced
uptake
at 795 K;
was achieved
at the
355 end of the program. content, maximum
As regards
the co-precipitates,
CZ-1, only began to show reduction before
effected;
that of high cobalt
reached,
reduction of cobalt
although
co-precipitate
of reduction
was
CZ-2, showed a small maximum fraction),
reduction
was achieved. lowered
to 645 K, and the maximum Kelvin degrees
By contrast,
the temperature
relative
was
impreg-
of
in hydrogen
uptake
to those observed
and total reduction
onto pure zirconia,
at
of the
began at 765 K, but again no major maximum
745 K, i.e. both by fifty impregnation
content,
of the B-Co(OH)2
about 70% reduction
nation onto the nickel initiation
no
the end of the ramp and no more than 10% reduction
630 K (probably major fraction
that of low cobalt
at 795 K, displayed
of cobalt
to for
and nickel
to zero valency was obtained.
DISCUSSION There are two major of a catalyst
results
to be considered:
of cobalt-nickel-zirconia
excess of 60 wt.% to C5+ hydrocarbons, obtained
by using a nickel-zirconia
zirconia
as support
and
of cobalt
studied,
only
co-precipitate,
them from the others.
witness,
reduction
high cobalt
temperature
final factor which defines
catalyst
studied
isation activity inferred
applies
by them, the l- olefins
increases
It is not initial
witness
CZ-2.
The at
is thus implied
2- olefins
to the present
are primary
Co-kieselguhr products,
on the support.
and Although
we have some evidence
with space velocity,
for the present
over
differ-
is high 1-ene, as measured
reaction
this point in detail,
to be deleterious
P-Me-but-P-ene
IZN-1.
that on the traditional
catalysts.
that the
indicating
a
From Table 4, high isomer-
for all but IZN-2 and IZN-3, and is
to chain growth.
Pichler et al [4] also report to produce
factors content,
and lowered
to the TPR results),
the difference
IZN-0,a
(Table 4).
of 1-olefins
situation
what
witness
high activity
arise by secondary
we have not studied
similar
content,
et al [4] report
isomeric olefins
proportion
to establish
onto
stream containing
It is not only high cobalt
(according
C4, C5 and C6 levels Pichler
respectively
give a product
It is not only high activity,
CZ-2.
even entirely
rather than pure
catalysts.
IZN-2and IZN-3, produced by
over 60 wt.% C5+, and it is of interest entiate
in
(ii) the higher activities
and cobalt + nickel
3 wt.% nickel-zirconia
(i) the production
shows selectivity
co-precipitate
for the cobalt-nickel
Among the catalysts impregnation
which
increases catalysts
IZ-2 and
that isomerisation
of the double
bond
with chain length, a result which also (Table 4).
The presence
of substantial
IZN-0 indicates that skeletal isomerisation
356 has occured
over these supports.
sites of much higher
strength
Results on the activity nickel-zirconia are included
This requires
than that needed for double and selectivity
co-precipitate,
in the present
lowering
temperature
throughout
of even C5+
IZN-3 is as
The function
of the impregnated
of IZN-0
cobalt
is a matter
in
is obvious
for conjecture.
first gives small nuclei of nickel uniformly
the sample, which
atomic hydrogen
[l], but
Impregnation
IZN-1 through
but the mode of action
We suspect that reduction
bond shift.
the 3 wt.%
C2 and C3, and increased
None of the preparations
the reduction
of acid
elsewhere
paper for comparison.
active per g of cobalt + nickel as IZN-0.
from the TPR results,
of IZN-0,
have been reported
a small amount of Co, in IZN-1, lowered substantially.
the presence
to facilitate
then operate reduction
by a spill-over
mechanism
of
of cobalt.
TABLE 5 Activity
and Selectivity
Catalyst
of Cobalt Catalysts
lmole CO
NCO see-'x103
sec-lg-lCo
E
Selectivity,
kJ mole-'
Cl
C2
C3
wt.% C4
Ref
C5+
2wt.X CO/A~~O~~
0.51
5.1
-
60
14
19
8
0
6
', H2/CO=3
0.85
8.6
112
64
11
15
6
4
6
10
19
7
65
8
21.4 36
95
46
9.9
-
139
5
", H2/CO=3
7
not given
-
78 131
4wt.% Co/Si02a
12
13
1OOCo 1OCu 18Th02 200 kieselguhrasb
a b
extrapolated excluding
to H2/C0 = 1.45, T = 523 K.
C02; selectivity
Some values are assembled
for activity
to the conditions
e.g.
and selectivity
as used by us. [6] are similar
for cobalt on other supports
are reported
of 4 wt.% Co/Si02, for the IZN- series
However,
the activities
obtained
by impregnation
selectivity
Detail of the selectivity to be absent
catalysts,
where necessary,
The values of activity to those obtained
IZ-1, -2 and -3.
strongly toward methane. as olefins
at T = 523 + 30 K, H2/C0 = 3.
in Table 5; these have been extrapolated,
2 wt.% Co/A1203 zirconia,
30
over alumina
is
is also different,
from the C4 fraction.
reported
for onto
In the case
[7] are now more like those
but the selectivity
to methane
is still
351
high, and CS+ production
is still low; the C4 fraction
Dent and Lin [8] have studied a view to optimising commercial
C2-C4 production,
formulation
reveal activity
a variety
Results
[2].
and selectivity
Lin do not detail
the C4 analysis
residue
but Pichler,
them non-Schulz-Flory-Anderson behaviour
(S.F.A.)
from the S.F.A. distribution
Cl and C2, isconmonly
reported.
catalysts
and Suhl have recently
hydrocarbon
However,
at high carbon
made a systematic
might be disturbed if readsorbed
and report
olefins
chains above a certain
to explain
are subject
'pile-up'
the observations,
to carbonium
based catalysts,
in the direction
that normal
to cracking
or if [9].
distribution
to account
than
for the deviations
if l- or 2- olefins and subsequent
can be of, say,
cracking
at
they may give rise to a
to catalysts
Fischer-Tropsch
of a high CS+ fraction
in the co-precipitate
leading
since
the S.F.A.
differences
in chain growth,
a much broader
ion formation
and nickel onto a nickel-zirconia nickel
Novak, Madon
that significant
participate
seen
in the Clo+ region.
It can be concluded modified
deviations
On the other hand, the second mechanism
acid sites on the zirconia minor
in distribution. at low carbon number,
length are subject
is to produce
in this case.
C12, which clearly
number are not.
and seems unlikely
014
[4]
81% 1-ene,
study of ways in which
the S.F.A. distribution,
applied
and Elstner
the additional
The effect of the former
observed
Dent and
-3 each shows an increasing
in the range C,. through
Deviant
can be obtained
Schultz
at 473 K, have reported
renders
distribution
from a well-tried
to IZN-2 and IZN-3.
data for IZN-1 through
per cent of product
with the present
with
n-butane.
The selectivity weight
starting
is 25% olefin.
based catalysts,
on the latter shown in Table 5
similar
over 100 Co 18 Th02 100 kieselguhr 3% 2-enes,
of cobalt
by impregnating
co-precipitate.
promotes
The presence
the reduction
with high activity
selectivity
of cobalt
as well as unusual
can be cobalt of
thus
selectivity.
ACKNOWLEDGEMENTS We gratefully National
acknowledge
Energy Research,
partial
Development
financial
We also wish to thank Miss 8. Terrell, Jaeger,
M. Jestrimski
ital aspects
of this work by Council.
Dr. K. Foger and Messrs.
for their participation
advice on presentation
given to us by Dr. J.R. Anderson
and preparation
H.
in experi-
of the work.
The constructive manuscript
and R. Sherwood
support
and Demonstration
of the
is very much appreciated.
358
REFERENCES l Bruce, L.A. and Mathews, J.F., Applied Catalysis, 4, 353 (1982). 2 St~cker, H.J., Annales de Chimie 13s. 5, 1459 (1960). 3 Anderson, R.B., "Catalysis", Vol. IV, ed. Emmett, P.H., Reinhold (1956). 4 Pichler, H., Schulz, H. and Elstner, it., Brennstoff-Chemie 48, 78 (1967). 5 Klug, H.P. and Alexander, L.E., 'X-Ray Diffraction Procedures', J. Wiley and Sons Inc., New York, 1954, p.491. 6 Vannice, M.A., J. Catalysis, 37, 449 (1975). 7 Vannice, M.A., J. Catalysis, 50, 228 (1977). 8 Dent, A.L. and Lin, M., Advances in Chemistry Series, Amer. Chem. Soc., 178 (1979) p.47. 9 Novak, S., Madon, R.J. and Suhl, H., J. Chem. Phys., 74, 6083 (1981); J. Catalysis, 77, 141 (1982).