مجال التميز
|
تميز دراسي و بحثي
|
|
|
البحوث المنشورة
|
|
عنوان البحث:
|
High catalytic
activity of silicalite in gas-phase ketonisation of propionic acid
|
رابط إلى البحث:
|
Link
|
تاريخ النشر:
|
07/03/2013
|
موجز عن البحث:
|
Amorphous silica
and crystalline silicalite (MFI structure) are demonstrated to be active and
environmentally benign catalysts for propionic acid ketonisation at 450–5008C
to form 3-pentanone. The silicalite is particularly efficient, and its ketonisation selectivity is
increased by base modification probably through generation of silanol nests
|
|
|
المؤتمرات
العلمية:
|
|
عنوان المؤتمر:
|
XIth European
Congress on Catalysis
|
تاريخ الإنعقاد:
|
1-6/09/2013 |
بلد ومكان الإنعقاد:
|
Lyon, France
|
طبيعة المشاركة:
|
Poster
|
عنوان المشاركة:
|
Gas-phase
ketonisation of propionic acid catalysed by Silicalite-1
|
موجز عن المشاركة:
|
Silicalite-1 are
demonstrated to be active catalysts for propionic acid ketonisation at
450-500oC to form 3-pentanone. Silicalite-1 with an MFI structure
is particularly efficient, with its ketonisation selectivity increasing by
basic modification. FTIR data indicates that the surface terminal silanol
groups may be responsible for the catalytic activity of silicalite-1.
Characterisation of the silicalite-1 catalyst with FTIR revealed significant
differences and gave important information about the active sites in the
ketonisation reaction. The base-modified silicalite-1 shows a sharp peak at
ca. 3740 cm-1 attributed to the terminal silanol groups and
a broad band around 3680 cm-1 attributed
to the hydrogen bonded vicinal silanols. Both bands increase in intensity
with increasing the pre-treatment temperature from 300 to 500oC.
In contrast, the unmodified silicalite-1 practically does not show the peak
for terminal silanols. This indicates that the surface nest silanols may be
the active sites responsible for the high selectivity of the base-modified
silicalite-1 in propionic acid ketonisation.
|
البحث (2):
|
|
عنوان البحث:
|
Highly Active and Recyclable Metal
Oxide Catalysts for the Prins Condensation of Biorenewable Feedstocks
|
رابط إلى البحث:
|
Click here
|
تاريخ النشر:
|
30/05/2014 |
موجز عن البحث:
|
Metal oxides such
as Nb2O5, Cr2O3, and especially a ZnII-CrIII mixed oxide are demonstrated to
be highly active and recyclable heterogeneous catalysts for Prins
condensation, which provides a clean, high-yielding route for the synthesis
of nopol through the condensation of biorenewable β-pinene with
paraformaldehyde. Zn-Cr mixed oxide with an optimum Zn/Cr atomic ratio
of 1:6 gave 100% nopol selectivity at 97% β-pinene conversion, with the
catalyst easily recovered and recycled. The acid properties of Nb2O5 and Zn-Cr mixed oxide were characterized by
the diffuse reflectance IR Fourier transform spectroscopy of adsorbed
pyridine and ammonia adsorption microcalorimetry. An appropriate combination
of acid-base properties of Zn-Cr mixed oxide is believed to be responsible
for its efficiency.
|
البحث (3):
|
|
عنوان البحث:
|
Ketonisation of carboxylic acids over
Zn-Cr oxide in the gas phase
|
رابط إلى البحث:
|
Click here
|
تاريخ النشر:
|
10/10/2014 |
موجز عن البحث:
|
Bulk Zn(II)-Cr(III)
mixed oxides with a Zn/Cr atomic ratio of 1:1–20:1 were found to be
active catalysts for the gas-phase ketonisation of carboxylic acids (acetic
and propionic) to form acetone and 3-pentanone, respectively, at 300–400 °C
and ambient pressure. Zn-Cr (10:1) oxide showed the best performance,
significantly exceeding that of the parent oxides ZnO and Cr2O3. The catalytic activity was further enhanced by supporting
Zn-Cr (10:1) oxide on TiO2 and γ-Al2O3. With 20%Zn-Cr/Al2O3, ketonisation of propionic acid occurred with 97% selectivity
to 3-pentanone at 99% conversion at 380 °C. Zn-Cr oxides were characterised
by BET, XRD, DRIFTS of pyridine and acetic acid adsorption and
microcalorimetry of ammonia adsorption. From DRIFTS, carboxylic acid adsorbed
dissociatively on Zn-Cr oxide to form a surface metal carboxylate in
bidentate bridging bonding mode. A mechanism for ketonisation of carboxylic
acids via β-ketoacid intermediate route has been proposed.
|
المؤتمرات العلمية:
|
|
المؤتمر (2):
|
|
عنوان المؤتمر:
|
7th Saudi Student Conference
|
تاريخ الإنعقاد:
|
1-2/02/2014 |
مكان الإنعقاد:
|
Edinburgh, UK
|
طبيعة المشاركة:
|
Oral Presentation
|
عنوان المشاركة 1:
|
Ketonisation of carboxylic acid over
Zn-Cr oxide in the gas phase
|
ملخص المشاركة1:
|
The aim of this
work was to study multifunctional catalysis for the conversion of
biomass-derived molecules to value-added chemicals and fuels in heterogeneous
systems. As the catalyst, oxides compounds possessing acid-base properties
were investigated in deoxygenation of carboxylic acids. ZnII-CrIII mixed
oxide was found to be an efficient bifunctional catalyst for ketonisation of
propionic acid to form 3-pentanone in the gas phase in continuous flow fixed
bed reactor at 350-450 oC. Different catalysts with different
atomic ratio of zinc and chromium (Zn/Cr = 1:1, 1:6, 10:1, 20:1 and 30:1) as
well as ZnO and Cr2O3 were
prepared by co-precipitation of ZnII and CrIII hydroxides. Catalysts under
study were characterised by a number of physical and chemical techniques such
as TGA (water content), BET (surface area and porosity) and XRD
(crystallinity). The nature of catalyst acidity was characterised by using
FTIR spectroscopy of adsorbed pyridine. The acid strength of catalysts was measured
by deferential scanning calorimetry of ammonia adsorption in the gas-solid
system. Amongst Zn-Cr oxides studied Zn-Cr (10:1) showed the best results
catalyst comparing with others oxides, so we supported this catalyst using
alumina, titania and silica by precipitataion method and impregnation as
well. 20% Zn:Cr (10:1) / TiO2 impregnation
was the best catalysts. It gave 99% conversion of propionic acid with 97%
3-pentanone selectivity at 380 oC. This catalyst showed stable
performance for 24 h without deactivation.
|
عنوان المشاركة 2:
|
High Catalytic Activity of Silicalite
in Gas-Phase Ketonisation of Propionic Acid
|
ملخص المشاركة 2:
|
Amorphous silica
and crystalline silicalite (MFI structure) are demonstrated to be active and
environmentally benign catalysts for propionic acid ketonisation at 450-500 oC
to form 3-pentanone. The silicalite is particularly efficient, and its
ketonisation selectivity is increased by a base modification probably
through generation of silanol nests. The aim of this work to present that
amorphous silica and silicalite are active in the reaction.
|
المؤتمر (3):
|
|
عنوان
المؤتمر:
|
Progress and Challenges in
Environmental Catalysis
|
تاريخ الإنعقاد:
|
23-24th June 2014
|
مكان الإنعقاد:
|
Johnson Matthey Technology Centre in
Reading
|
طبيعة المشاركة 1:
|
Poster
|
عنوان المشاركة 1:
|
Metal oxides as
highly active catalysts for Prins condensation
|
ملخص المشاركة 1:
|
Nopol was obtained
by Prins condensation, over bulk ZnII-CrIII mixed
oxides, silica-supported catalysts and niobium oxides. Amongst the metal
oxides, Cr2O3 showed the best activity with 100% nopol
selectivity, while ZnO showed very low activity. Activity was improved by
adding ZnII to CrIIIoxides. Zn-Cr (1:6) oxide
proved a highly active and recyclable heterogeneous catalyst for the clean,
high-yielding synthesis of nopol by Prins condensation of pinene with
paraformaldehyde. 20 wt% of this catalyst was supported on silica and it
performed as well as bulk catalyst, giving 100% selectivity at 94%
conversion. Nb2O5 exhibited
high activity of β-pinene and selectivity of nopol. Increasing the
calcination temperature affected catalyst performance negatively, by reducing
the number of acid active sites.
|
طبيعة المشاركة 2:
|
Poster
|
عنوان المشاركة
2:
|
High Catalytic
Activity of Silicalite in Gas-Phase Ketonisation of Propionic Acid
|
ملخص المشاركة 2:
|
High purity
amorphous silicas and crystalline silicalite (MFI structure) were found to be
active catalysts of the deoxygenation of propionic acid. Silicalite was
prepared by the hydrothermal method. Silica and silicalite were treated with
aqueous acidic (HCl) and basic (NH3+NH4NO3 (aq) or NH3 (aq)) solutions in a Teflon-lined autoclave. The reaction was
carried out in a fixed-bed continuous flow reactor in the gas phase at
400-500 °C, 20 ml min-1N2 flow
rate, using 0.2 g of catalyst. A preliminary blank reaction showed a small
contribution of homogeneous catalysis at 500 °C, with 12% of propionic
acid converted to form 3-pentanone. Secondly, the treatment did not affect
silica activity; it showed only 85% selectivity with 39% conversion at
500 °C. HZSM-S zeolite (Si/Al = 180) possessing strong acid sites showed
low catalytic activity at 400-500 °C and the main product was ethane.
Silicalite had higher activity and selectivity of 3-pentanone than silica.
Acidic treatment had little effect on catalyst activity, whereas basic
treated silicalite was the most active catalyst in the deoxygenation of
propionic acid at 500 °C, because silanol nests formed on the silicalite
surface, acting as catalytically active sites for the reaction. Catalyst
activity increased with increasing reaction temperature from 400-500 °C.
Silicalite performance was stable for at least 28 h time on stream at 50°C,
with 84-92% of 3‑pentanone selectivity at 93-80% conversion of acid.
|
المؤتمر (4):
|
|
عنوان المؤتمر:
|
8th Environmental Catalysis Conference (8th ECC)
|
تاريخ الإنعقاد:
|
August 2014
|
مكان الإنعقاد:
|
Asheville, USA
|
طبيعة المشاركة:
|
Oral presentation
|
عنوان المشاركة:
|
High catalytic
activity of silicalite in gas-phase ketonisation of propionic acid
|
ملخص المشاركة 2:
|
High purity
amorphous silicas and crystalline silicalite (MFI structure) were found to be
active catalysts of the deoxygenation of propionic acid. Silicalite was
prepared by the hydrothermal method. Silica and silicalite were treated with
aqueous acidic (HCl) and basic (NH3+NH4NO3 (aq) or NH3 (aq)) solutions in a Teflon-lined autoclave. The reaction was
carried out in a fixed-bed continuous flow reactor in the gas phase at
400-500 °C, 20 ml min-1N2 flow
rate, using 0.2 g of catalyst. A preliminary blank reaction showed a small
contribution of homogeneous catalysis at 500 °C, with 12% of propionic
acid converted to form 3-pentanone. Secondly, the treatment did not affect
silica activity; it showed only 85% selectivity with 39% conversion at
500 °C. HZSM-S zeolite (Si/Al = 180) possessing strong acid sites showed
low catalytic activity at 400-500 °C and the main product was ethane.
Silicalite had higher activity and selectivity of 3-pentanone than silica.
Acidic treatment had little effect on catalyst activity, whereas basic
treated silicalite was the most active catalyst in the deoxygenation of
propionic acid at 500 °C, because silanol nests formed on the silicalite
surface, acting as catalytically active sites for the reaction. Catalyst
activity increased with increasing reaction temperature from 400-500 °C.
Silicalite performance was stable for at least 28 h time on stream at 50°C,
with 84-92% of 3‑pentanone selectivity at 93-80% conversion of acid.
|
المؤتمر (4):
|
|
عنوان المؤتمر:
|
8th Environmental Catalysis Conference (8th ECC)
|
تاريخ الإنعقاد:
|
August 2014
|
مكان الإنعقاد:
|
Asheville, USA
|
طبيعة المشاركة:
|
Oral presentation
|
عنوان المشاركة:
|
High catalytic activity of silicalite
in gas-phase ketonisation of propionic acid
|
ملخص المشاركة:
|
Amorphous silica
and crystalline silicalite (MFI structure) are demonstrated to be active and
environmentally benign catalysts for propionic acid ketonisation at 450–500 oC
to form 3-pentanone. The silicalite is particularly efficient, and its
ketonisation selectivity is increased by base modification probably through
generation of silanol nests.
|
|
|
المؤتمر (5):
|
|
عنوان المؤتمر:
|
Applied Catalysis and Reaction
Engineering
|
تاريخ الإنعقاد:
|
September 2014
|
مكان الإنعقاد:
|
Cambridge University, Cambridge, UK
|
طبيعة المشاركة:
|
Oral presentation
|
عنوان المشاركة:
|
Highly Active and
Recyclable Metal Oxide Catalysts for the Prins Condensation of Biorenewable
Feedstocks
|
ملخص المشاركة:
|
Metal oxides such
as Nb2O5, Cr2O3, and especially a ZnII-CrIII mixed oxide are demonstrated to
be highly active and recyclable heterogeneous catalysts for Prins
condensation, which provides a clean, high-yielding route for the synthesis
of nopol through the condensation of biorenewable β-pinene with
paraformaldehyde. Zn-Cr mixed oxide with an optimum Zn/Cr atomic ratio of 1:6
gave 100% nopol selectivity at 97% β-pinene conversion, with the catalyst
easily recovered and recycled. The acid properties of Nb2O5 and Zn-Cr mixed oxide were characterized by the diffuse
reflectance IR Fourier transform spectroscopy of adsorbed pyridine and ammonia
adsorption microcalorimetry. An appropriate combination of acid-base
properties of Zn-Cr mixed oxide is believed to be responsible for its
efficiency.
|