الفهرس 
ntroduction to CatalysisOnly 14 pages are availabe for public view
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Abstract
SUMMARY AND CONCLUSIONS
1- Pt and Ni NPs supported on alumina and /or silica (commercially supplied),
synthesized via microwave assisted irradiation technique (MAS) exhibited
higher surface areas, with lower pore dimensions especially for diluted samples
improved dispersion profile and, better catalytic activity and selectivity,
compared with those samples synthesized by traditional rotary chemical
evaporation technique (RCE).
2- Electrical measurements confirmed that the electromagnetic radiations in
MAS method enhance the even distribution of smaller in size Pt NPs
accompanied with higher concentration of grain boundaries, generating highly
mobile electrons and lattice vibrations (phonons), as compared with
nanoparticles produced during RCE method.
3- The synthesized γ- alumina nanopowder as well as the alumina samples
modified by CTAB and pluronic triblock (P123) had highly crystalline structure
with cubic spinel lattice (space group Fd3m). Alumina modified by using 2.5
gm of CTAB (cationic surfactant) was chosen as a support for further study, as
it exhibited higher surface parameters, lower pore dimensions and highest
thermal stability. The reduction process proceeded through ultrasonic method
(US) or microwave assisted solution irradiation (MAS).
4- Synthesized silica nanopowders and its modified samples by CTAB and
P123 exhibited amorphous structure. Both parent silica (S
1
) and modified one
(S
1
C) were loaded with 0.9 wt% Pt or 5.0 wt% Ni in a sol-gel synthesis via
ultrasonic (US) or microwave assisted solution irradiation (MAS). The S1
C
(modified silica specifically by 2.5 gm CTAB) displayed low angle-XR
diffraction characteristic of MCM-41 of hexagonal symmetry structure (P6mm),
exhibiting high surface area, proper pore size distribution, well homogeneity
and high thermal stability.
5- The 0.9 Pt/AC2.5 (MAS)
nanocatalyst sample prepared by microwave assisted
solution method) showed higher catalytic activity for n-hexane
dehydrocyclization reaction into benzene than the same sample prepared by
ultrasonic method (0.9 Pt/ AC2.5 (US)). On the other hand, the 5 Ni/AC
2.5 (MAS)
was much more active for n-hexane cracking than the 5 Ni/ AC
2.5 (US)
.
0.6 Pt/ S
1
C (US)
exhibited higher catalytic activity towards n-hexane
dehydrocyclization than 0.9Pt/S
1
C (MAS). The 5Ni/S1 (MAS)
sample showed the
much higher activity toward n-hexane cracking (96% at 450
°
C) than the same
nanocatalyst prepared by US method (5Ni/S
1(US)
) (82% at 450
°
C). However,
the 5Ni/S
1
C (US)
displayed the highest cracking activity (94%), as compared
with 5 Ni/ S1
C (MAS)
(82%).
6- The catalytic activity for cyclohexane dehydrogenation increases by
increasing both Pt content on modified alumina (AC
2.5
) and modified silica
(S
1
C) as well as with increasing the reaction temperature. The selectivity
achieved 100% over the whole range of reaction temperatures for the catalyst
samples prepared by the two techniques (MAS and US).
- The 0.9 Pt/ AC2.5 (MAS)
showed higher cyclohexane dehydrogenation activity
(86% at 450
°
C) than the same sample prepared by US (0.9 Pt/ AC2.5 (US)) (75%
at 450
°
C).
- The 5Ni/AC2.5 (MAS) sample seemed more active than the same sample
prepared by US (5Ni/AC2.5 (US)
).
- The 0.9 Pt/S1 (US)
(the parent silica nanopowder) was more active (75%
benzene vs. 51% in case of 0.9 Pt/ S
1 (MAS)
).
- The 0.9 Pt/S1
C (MAS)
(modified silica nanopowder with 2.5 g CTAB) revealed
higher dehydrogenation activity (83% benzene vs. 40 % in case of 0.9Pt/S
1C
(US)). .
- The 5 Ni/ S1 (US)
and the corresponding 5Ni/ S
1 (MAS)
showed nearly the same
cyclohexane dehydrogenation trend. However, the 5Ni/ S1C (MAS) showed higher
dehydrogenation activity than the 5Ni/ S
1
C (US).
7- In ethanol conversion, the 0.3 Pt/ AC
2.5 (US)
sample was the most active for
ethanol dehydration into ethylene (60% ethylene yield), compared with the
other Pt loaded samples. .
- Both the 5 Ni/ AC
2.5 (MAS) and 5 Ni/ AC
2.5 (US)
nanocatalyst samples showed
the same catalytic activity trend in ethylene production with little yield of
acetaldehyde.
- The 0.9 Pt/ S1 (US) was more active than 0.9 Pt/S1 (MAS)
and the 5 Ni/ S
1 (MAS)
was more active than 5 Ni/ S1 (US)
for ethylene production.
- The 0.9 Pt/ S1
C (MAS) was more active than the 0.9 Pt/ S1
C (US)
.
- Both 5 Ni/ S1
C (US) and 5 Ni/ S
1
C (MAS)
were active in this reaction (yielding
61% ethylene in both cases over temperature range 350
°
C to 450
°
C.
8- The MIL-101 as a member of Cr- MOF family, had higher specific surface
area ( SBET
= 2100 m
2
/g ) , pronounced decrease in pore radius(< 2 nm) and
extremely lower thermal stability up to 350
°
C than the other support systems
under study (Al
2O3 & SiO2
).
~ 75% wt losses were observed up to 570
°
C. This means that ~25% chromium
oxide content was maintained in the Mil-101 framework.
9- The TEM image of Mil-101 and the corresponding Pt & Ni loaded samples
showed cubo-octahedral crystals in shape of uniform size of ~ 212 nm.
10- The 0.9 Pt/ Mil-101 and 5 Ni / Mil-101 loaded samples were in situ reduced
via RCE method.
11- in catalytic conversion of ethanol on these nano catalytic systems, the
5Ni/Mil-101 exhibited much higher activity than bare Mil-101 or 0.9 Pt/ Mil-101 toward ethylene production ( dehydration pathway) (59% yield) and 100%
selectivity over whale range of temperature. It is to be mentioned that 0.9 Pt/
Mil-101 produced 46% ethylene at 300
°
C together with 11% acetaldehyde at
300
°
SUMMARY AND CONCLUSIONS
1- Pt and Ni NPs supported on alumina and /or silica (commercially supplied),
synthesized via microwave assisted irradiation technique (MAS) exhibited
higher surface areas, with lower pore dimensions especially for diluted samples
improved dispersion profile and, better catalytic activity and selectivity,
compared with those samples synthesized by traditional rotary chemical
evaporation technique (RCE).
2- Electrical measurements confirmed that the electromagnetic radiations in
MAS method enhance the even distribution of smaller in size Pt NPs
accompanied with higher concentration of grain boundaries, generating highly
mobile electrons and lattice vibrations (phonons), as compared with
nanoparticles produced during RCE method.
3- The synthesized γ- alumina nanopowder as well as the alumina samples
modified by CTAB and pluronic triblock (P123) had highly crystalline structure
with cubic spinel lattice (space group Fd3m). Alumina modified by using 2.5
gm of CTAB (cationic surfactant) was chosen as a support for further study, as
it exhibited higher surface parameters, lower pore dimensions and highest
thermal stability. The reduction process proceeded through ultrasonic method
(US) or microwave assisted solution irradiation (MAS).
4- Synthesized silica nanopowders and its modified samples by CTAB and
P123 exhibited amorphous structure. Both parent silica (S
1
) and modified one
(S
1
C) were loaded with 0.9 wt% Pt or 5.0 wt% Ni in a sol-gel synthesis via
ultrasonic (US) or microwave assisted solution irradiation (MAS). The S1
C
(modified silica specifically by 2.5 gm CTAB) displayed low angle-XR
diffraction characteristic of MCM-41 of hexagonal symmetry structure (P6mm),
exhibiting high surface area, proper pore size distribution, well homogeneity
and high thermal stability.
5- The 0.9 Pt/AC2.5 (MAS)
nanocatalyst sample prepared by microwave assisted
solution method) showed higher catalytic activity for n-hexane
dehydrocyclization reaction into benzene than the same sample prepared by
ultrasonic method (0.9 Pt/ AC2.5 (US)). On the other hand, the 5 Ni/AC
2.5 (MAS)
was much more active for n-hexane cracking than the 5 Ni/ AC
2.5 (US)
.
0.6 Pt/ S
1
C (US)
exhibited higher catalytic activity towards n-hexane
dehydrocyclization than 0.9Pt/S
1
C (MAS). The 5Ni/S1 (MAS)
sample showed the
much higher activity toward n-hexane cracking (96% at 450
°
C) than the same
nanocatalyst prepared by US method (5Ni/S
1(US)
) (82% at 450
°
C). However,
the 5Ni/S
1
C (US)
displayed the highest cracking activity (94%), as compared
with 5 Ni/ S1
C (MAS)
(82%).
6- The catalytic activity for cyclohexane dehydrogenation increases by
increasing both Pt content on modified alumina (AC
2.5
) and modified silica
(S
1
C) as well as with increasing the reaction temperature. The selectivity
achieved 100% over the whole range of reaction temperatures for the catalyst
samples prepared by the two techniques (MAS and US).
- The 0.9 Pt/ AC2.5 (MAS)
showed higher cyclohexane dehydrogenation activity
(86% at 450
°
C) than the same sample prepared by US (0.9 Pt/ AC2.5 (US)) (75%
at 450
°
C).
- The 5Ni/AC2.5 (MAS) sample seemed more active than the same sample
prepared by US (5Ni/AC2.5 (US)
).
- The 0.9 Pt/S1 (US)
(the parent silica nanopowder) was more active (75%
benzene vs. 51% in case of 0.9 Pt/ S
1 (MAS)
).
- The 0.9 Pt/S1
C (MAS)
(modified silica nanopowder with 2.5 g CTAB) revealed
higher dehydrogenation activity (83% benzene vs. 40 % in case of 0.9Pt/S
1C
(US)). .
- The 5 Ni/ S1 (US)
and the corresponding 5Ni/ S
1 (MAS)
showed nearly the same
cyclohexane dehydrogenation trend. However, the 5Ni/ S1C (MAS) showed higher
dehydrogenation activity than the 5Ni/ S
1
C (US).
7- In ethanol conversion, the 0.3 Pt/ AC
2.5 (US)
sample was the most active for
ethanol dehydration into ethylene (60% ethylene yield), compared with the
other Pt loaded samples. .
- Both the 5 Ni/ AC
2.5 (MAS) and 5 Ni/ AC
2.5 (US)
nanocatalyst samples showed
the same catalytic activity trend in ethylene production with little yield of
acetaldehyde.
- The 0.9 Pt/ S1 (US) was more active than 0.9 Pt/S1 (MAS)
and the 5 Ni/ S
1 (MAS)
was more active than 5 Ni/ S1 (US)
for ethylene production.
- The 0.9 Pt/ S1
C (MAS) was more active than the 0.9 Pt/ S1
C (US)
.
- Both 5 Ni/ S1
C (US) and 5 Ni/ S
1
C (MAS)
were active in this reaction (yielding
61% ethylene in both cases over temperature range 350
°
C to 450
°
C.
8- The MIL-101 as a member of Cr- MOF family, had higher specific surface
area ( SBET
= 2100 m
2
/g ) , pronounced decrease in pore radius(< 2 nm) and
extremely lower thermal stability up to 350
°
C than the other support systems
under study (Al
2O3 & SiO2
).
~ 75% wt losses were observed up to 570
°
C. This means that ~25% chromium
oxide content was maintained in the Mil-101 framework.
9- The TEM image of Mil-101 and the corresponding Pt & Ni loaded samples
showed cubo-octahedral crystals in shape of uniform size of ~ 212 nm.
10- The 0.9 Pt/ Mil-101 and 5 Ni / Mil-101 loaded samples were in situ reduced
via RCE method.
11- in catalytic conversion of ethanol on these nano catalytic systems, the
5Ni/Mil-101 exhibited much higher activity than bare Mil-101 or 0.9 Pt/ Mil-101 toward ethylene production ( dehydration pathway) (59% yield) and 100%
selectivity over whale range of temperature. It is to be mentioned that 0.9 Pt/
Mil-101 produced 46% ethylene at 300
°
C together with 11% acetaldehyde at
300
°
C.