0.55 MB Super acid poster 2

250
1000/800
800/800
DHoads /kjmol-1)
200
Development of new Ce / La / Zr
Super Acid Catalysts
P.O. Box 6, Clifton Junction, Swinton,
Manchester M27 8LS, England.
150
100
250
50
0
0
Nikkei-MEL, 4025-1, Shimizu-Miho, Shizuoka City,
Shizuoka Prefecture, 424-0901, Japan.
0.01
H. Stephenson,* H. Bradshaw,
250 D. Harris, S. Ward,
0.02 0.03 0.04 0.05 0.06 0.07
150
MEL
Chemicals, PO Box 6, Lumns Lane, Swinton,
Manchester M27 8LS, England. 1000/800
Surface Coverage (mmol g-1)
800/800
R. Brown and H.Williams, University of Huddersfield, Centre
for Applied Catalysis, Huddersfield, HD1
3D, England.
200
A Luxfer Group Company
100
*Tel: +44 161 911 1179, Fax: +44 161 911 1052, e-mail: [email protected]
Cl
CH3
CH3
Microcalorimetry
Data
-HCl
+
+ as Doads(NH3)200°C vs amount
Data, presented
of NH3
3C
adsorbed, is shown below in Figure 1. The H
measured
acid
strength
a XZO
HO 1291 sample
CHof
CH3originally calcined at
3
800°C depends markedly
on the temperature at which it
-H2O
+
+
is activated immediately
prior to measurement.
Strong
H3C-1
o
sites (D ads(NH3)200C approaching 200 kJ mol
) are only
detected after activation at 800°C. Even after 700°C
activation, these sites are not detected.
200°C
400°C
600°C
700°C
800°C
CeO2 La2O3
(wt%) (wt%)
DHoads / kjmol-1)
150
130
+
200°C
400°C
600°C
1000/800
700°C
800/800
800°C
250
5E-11
4E-11
200
3E-11
150
2E-11
100
50
0
XZO
1523
Y/Zr
-
-
6.2
-
-
0
0
0
84
0.14
-
6.0
6.2
XZO
1291
Ce/La/Zr
93
0.42
2.8
15.0
4.4
XZO
1291/04
Ce/La/Zr
80
0.53
15
16.0
4.6
XZO
1835/01
Ce/La/Zr
89
0.44
21
21.5
6.1
XZO
1834/01
Ce/La/Zr
67
0.46
28
11.5
3.3
XZO
1833/01
Ce/La/Zr
90
0.43
18
16.0
5.9
XZO
1832/01
Ce/La/Zr
83
0.50
16
16.0
3.3
100
0.01
300 400 500 600 700 800
Temperature (°C)
0.02 0.03 0.04 0.05 0.06 0.07
Surface Coverage (mmol g-1)
200
Figure 2: Doads(NH3)[at 200°C]. Sample XZO 1291 –
calcined at 1000°C, activated at 800°C prior to
adsorption (1000/800), compared with the same sample
Cl and activated
CH37E-09
calcined
at 800°C
CH3 at 800°C (800/800).
200°C
-HCl
6E-09
400°C
+
+
600°C
H3Calso
A XZO 1291 sample calcined
at 1000ºC was
5E-09
700°C
investigated, activated
at 800ºC and 600ºC prior to
HO
800°C CH3
CH3
4E-09 at 200ºC. As with material calcined at
NH3 adsorption
-H2O
800°C, the +
strength of acid sites on a sample
calcined
+
3E-09
H3Cat which it
at 1000°C is dependent on the temperature
Pressure / torr
Ce/La/Zr
2E-09
is activated
prior to ammonia adsorption. However, it is
worth noting
that the few strongest sites on the
1E-09
“1000°C” sample still show higher acid strength than
+09
0E
210
those on the “800°C” sample (Figure 2).
0
Table 1: Summary of the characterisation data for
a selection of samples. (All samples were calcined
at 800°C)
100
200
190
Pressure / torr
Pressure / torr
DHoads / kjmol-1)
170
150
700 800
300 400 500 600 200°C
Temperature (°C)
400°C
600°C
700°C
800°C
130
7E-09
6E-11
110
200°C
400°C
600°C
700°C
800°C
90
5E-11
70
4E-11
50
3E-110
0.01
6E-09
90
0.07
2E-09
1E-11
6E-11
1E-09
5E-110
0E+09
0.02
0 200 400 600 800
Temperature (°C)
4E-09
200°C
2E-09
4E-09
1E-09
3E-09
0E+09
2E-09 0
800°C
200°C
400°C
0 200 400
600 800
600°C
700°C(°C)
Temperature
800°C
0.03
0.04
0.05
0.06
0.07
0
5E-11
7000
1E-11
100
200
XZO 1291/04
300 400 500 600
Temperature (°C)
700
800
700
800
300 400 500 600
Temperature (°C)
7E-09
200°C
400°C
6E-09
600°C
700°C
5E-09
800°C
7E-09
200°C
4E-09
400°C
6E-09
600°C
3E-09
700
800
200
100
200
0E+09
6E-11
6000
0
0
5000
300 400 500 600
Temperature (°C)
100
1E-09
2E-11
s/s
0.01
Surface Coverage
(mmol
Activation
Conversion
of g-1)Average
temperature (°C) benzyl chloride D Hads(NH3)
70
after 1 hr / %
50
Reaction A
(Benzyl
0.01chloride)
0.02 0.03 0.04 0.05 0.06 0.07
6E-11 0
XZO 1291
none
Surface
Coverage<1
(mmol g-1) 200°C
XZO 1291
200
<1
< 100
400°C
5E-11
600°C
700
3
123
XZO 1291
700°C
XZO
1291
800
65
155
4E-11
6E-11
800°C
XZO 1291
1000
<1
200°C
XZO
1291
800
<1
150
3E-11
400°C
5E-11
(calcined 1000 °C)
600°C
XZO
1832/01
800
<1
119
700°C
2E-11
4E-11
800°C
2
129
800
XZO 1833/01
XZO
1834/01
800
<1
127
1E-11
3E-11
XZO 1835/01
800
3
130
XZO2E-11
1719/01
800
4
133
0
700
0
100
200
300
400
500
600
XZO 1662/02
800
15
131* 800
Temperature
(°C)
XZO1E-11
1523
800
<1
118
Fe AlMCM-41
150
30
(Si/Al = 15)
0
0
100 150
200 300 400 2.5
500 600 700 800
Al AlMCM-41
Temperature (°C)
(Si/Al = 15)
Reaction B (Benzyl alcohol)
XZO
1291
800
<1
155
7E-09
200°C
Fe AlMCM-41
150
15
6E-09
400°C
(Si/Al
= 15)
600°C
Al AlMCM-41
150
39
5E-09
700°C
(Si/Al
=
15)
7E-09
800°C
3E-11
4000
0
2: Summary
of the catalytic activity of the alkylation
Table
6E-09
400°C
of 3E-09
toluene using600°C
benzyl chloride and benzyl alcohol at
5E-09
85°C.
*High surface
coverage >0.1mmol g-1
700°C
5E-09
4E-09
0.02 0.03 0.04 0.05 0.06
Surface Coverage
3E-09(mmol g-1)
2E-11
4E-11
400°C
600°C
The 170
only sample which shows significant catalytic700°C
activity
210
is the
XZO 1291 sample activated at 800°C prior to
reaction.
800°C
150
200°C
The XZO1291
sample activated at 700°C had a 1%
190
130
400°C
conversion while some other samples did show some
600°C
170 activity but the conversion was too small to measure.
catalytic
110
700°C
A second
batch
reaction
was
used,
the
alkylation
of
800°C
150
90
toluene with benzyl alcohol. The XZO 1291 activated and
130
70 at 800°C showed no catalytic activity, suggesting
calcined
that 110
the
50 catalyst has Lewis acid sites.
Reference
1E-11
-
190
0.07
0.02 0.03 0.04 0.05 0.06
Surface Coverage (mmol g-1)
6E-11
-
XZO
1719/01
0.01
Figure 1: Doads(NH3)[at 200°C]. Sample XZO 1291 calcined
at 800°C, activated at 200-800°C prior to adsorption.
3.8
+
H3C
210
0
0.34
A range of different doped zirconium oxides have
been prepared, all are single phase by XRD with
crystallite size 7-10nm, but have differing surface
areas and particle sizes. (Table 1)
•
Catalytic testing results indicate the generation of
Lewis acid sites in XZO 1291 sample when activated
at 800°C. (Table 2)
•
For XZO 1291 samples the measured acidity depends
crucially on how the material is activated in the
calorimeter prior to ammonia adsorption, as
well as on the temperature at which the material
was calcined originally. (Figures 1 & 2)
•
There appears to be a very specific composition
range which generates acidic sites when calcined
and activated at 800°C.
•
The addition of La2O3 is normally thought to
improve surface area stability and enhance basicity,
but its presence appears critical to the development
of acid sites.
•
•
Future work investigating the effects of composition
and particle size is underway.
200°C
Reaction B: alkylation of toluene with benzyl alcohol
50
129
CH3
-H2O
90
Si/Zr
HO
CH3
110
XZO
1662/02
+
H3C
Cl alkylation of toluene
HO
CH33
Reaction
A:
with benzyl chloride
CH33
CH
CH
-HCl
2O studied using benzyl alcohol in
The reaction
was -H
also
+
+
+
+
place of benzyl chloride, using the same Hconditions.
H33CC
-1o
DH
DHoads / kjmol
)ads / kjmol-1)
Dopants Surface Pore
d50
area volume (µm)
(m2/g) (ml/g)
CH3
-HCl
Pressure / torr
Pressure / torr
Characterisation
Cl
CH3
70
-1) / torr
Pressure
DHoads /kjmol
Results and discussion
170
•
Surface Coverage (mmol g-1)
+
190
Oxide with varying Ce : La : Zr were prepared by a range
of different commercialised processes.[2] Samples were
calcined at temperatures between 300-1000°C using
ramp rate 3°C / min and dwell of 3 hours in static air.
The samples were then activated in situ at temperature
200 - 800°C under dried helium flow at 5ml min-1. Small
pulses (typically 1ml) of the probe gas (1% NH3 in He)
were injected at regular intervals into the carrier gas
stream. The net amount of ammonia irreversibly adsorbed
from each pulse was determined from the MS signal.
This data was combined with the enthalpies of ammonia
adsorption for each pulse, measured in a flow-through
calorimeter, to give a DHoads(NH3) vs NH3 adsorbed
profile which could be interpreted in terms of an acid site
strength distribution profile for the catalyst sample.[3,4]
Conclusions
0
The reaction
used was the alkylation of toluene with
0
0.01 0.02 0.03 0.04 0.05 0.06 0.07
benzyl chloride. A mixture of 0.10 mole of toluene,
0.005
Surface Coverage (mmol g-1)
50
mole of benzyl chloride and 0.005 mole of tetradecane
internal standard was added to 0.25g of the catalyst.
0
The reaction
was carried out at 85°C in a stirred reactor.
0
0.01 0.02 0.03 0.04 0.05 0.06 0.07
The products were analysed by GC (Varian 3900).
210
Experimental
150
50
testing
Catalyst
100
Pressure / torr
Pressure / torr
Zirconium oxide doped with sulphate and tungstate are
known to be solid acids, however it has recently come to
light that ceria and lanthana doped zirconium oxide may
also exhibit strong acid sites as well as the expected basic
sites.[1] This work investigates dependence of strong acid
sites on calcination and activation conditions and looks
at how this acidity can be used in real applications via
catalyst testing, the reactions being specifically chosen
to give information to the type and strength of acid sites.
essure / torr
Introduction
Product
1000/800
800/800
200
-1o
DH
DHoads /kjmol
)ads /kjmol-1)
Magnesium Elektron Inc., 500 Point Breeze Rd,
Flemington, NJ 08822, USA
4E-11
6E-11
3E-11
5E-11
Future work investigating additional reactions and
further characterisation of acidic and basic sites is
planned.
Samples
For further information or samples please contact:
[email protected]
References
1. M.G. Cutrufello, I. Ferino, R. Monaci, E. Rombi,
V. Solinas, Acid-base properties of zirconium
cerium and lanthanum oxides. Topics in Catalysis,
19 (2002)
2. Y. Takao, C. Norman, G. Edwards, I. Chisem,
WO/03/037506
3. S. P. Felix, C. S. Jowitt, D. R. Brown, Thermochim.
Acta 433 (2005) 59.
4. P. F. Siril, A. D. Davison, J. K. Randhawa and
D. R. Brown, J. Mol. Catal. A 267, (2006) 72.