سفر طالع سفر المطيري

الاسم الاول: 
سفر
اسم العائلة: 
المطيري
الدرجة العلمية: 
دكتوراة
مجال الدراسة: 
العلوم والتقنية
المؤسسة التعليمية: 
The University of Liverpool

 

 

مجال التميز

تميز دراسي و بحثي

 

 

البحوث المنشورة

 

البحث (1):

 

عنوان البحث:

Ketonisation Of Acetic Acid On Metal Oxides: Catalyst Activity, Stability And Mechanistic Insights

رابط إلى البحث:

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تاريخ النشر:

15/08/2018

موجز عن البحث:

Ketonisation of acetic acid to acetone was studied in the gas phase using γ-Al2O3, TiO2, ZrO2 and CeO2 as the catalysts in the temperature range of 180–350 °C and ambient pressure. Catalyst activity was found to increase in the order Al2O3 << TiO2 < ZrO2 < CeO2. CO2-TPD showed that relatively weak base sites on oxide surfaces are essential for the ketonisation activity, whereas no relation between oxide acidity and catalytic activity was observed. Catalyst resistance to deactivation increased in the order CeO2 << ZrO2 < TiO2 in parallel with the amount of coke formed. TiO2 (Degussa P25) and ZrO2 were found to exhibit the best performance as represented by their activity and stability to deactivation. CeO2 and ZrO2 could be regenerated by air calcination to regain their activity. DRIFTS studies of acetic acid adsorption on oxide surfaces found facile exchange between adsorbed bidentate bridging acetate species and gas-phase acetic acid at 130 °C, well below temperature threshold of acid ketonisation, indicating fast equilibration of different forms of surface acetate species in the ketonisation system. At higher temperatures typical for acid ketonisation, in the absence of gas-phase acetic acid, the adsorbed bidentate bridging acetate-d3 species were found to undergo H/D exchange with proton sites on oxide surfaces. This provides experimental evidence supporting the intermediacy of enolate species in acid ketonisation. 

 

 

المؤتمرات العلمية:

 

المؤتمر (1):

 

عنوان المؤتمر:

The UK Catalysis Conference 2018 (UKCC2018)      

تاريخ الإنعقاد:

 03/01/2018

مكان الإنعقاد:

Loughborough.UK

طبيعة المشاركة:

Poster Presentation

عنوان المشاركة:

Ketonisation Of Acetic Acid To Acetone Catalysed By Metal Oxides In The Gas Phase.

ملخص المشاركة:

Ketonisation of carboxylic acids is widely used as a clean, non-polluting method for the synthesis of ketones. It also attracted significant interest for the upgrading of biomass-derived oxygenates, e.g., bio-oil. Here, ketonisation of acetic acid, was studied over γ-alumina, titania, zirconia and ceria catalysts in the gas phase. Acetone was formed as the primary reaction product with > 99% selectivity. Small amounts of isobutene arising from acetone condensation were also formed at high acetic acid conversions. Catalyst activity was found to increase in the order Al2O3 << TiO2 < ZrO2 < CeO2. These catalysts, except TiO2, suffered from deactivation probably due to catalyst coking; the most coked CeO2 showed the strongest deactivation. Another possible cause of CeO2 deactivation is reduction of Ce(IV) to Ce(III) in the reaction system. This is supported by significant improvement of catalysts stability when using air as the carrier gas instead of N2. The activity of γ-Al2O3 increased with increasing the basicity of alumina surface, which indicates the importance of catalyst basic sites. The reaction rate increased with increasing the partial pressure of acetic acid tending to plateau, which suggests a Langmuir-Hinshelwood mechanism. There was no kinetic isotope effect observed in reaction with CH3COOD, which indicates that ketonisation reaction is not limited by the formation of surface acetate species.

 

 

المؤتمر (2):

 

عنوان المؤتمر:

The UK Catalysis Conference 2019 (UKCC2019)    

تاريخ الإنعقاد:

Loughborough. UK

مكان الإنعقاد:

09/01/2019

طبيعة المشاركة:

Poster Presentation

عنوان المشاركة:

Ketonisation Of Acetic Acid On Metal Oxides: Catalyst Activity, Stability And Mechanistic Insights

ملخص المشاركة:

Ketonisation of acetic acid to acetone was studied in the gas phase using γ-Al2O3, TiO2, ZrO2 and CeO2 as the catalysts in the temperature range of 180–350 °C and ambient pressure. Catalyst activity was found to increase in the order Al2O3< <TiO2<ZrO2<CeO2. CO2-TPD showed that relatively weak base sites on oxide surfaces are essential for the ketonisation activity, whereas no relation between oxide acidity and catalytic activity was observed. Catalyst resistance to deactivation increased in the order CeO2< <ZrO2<TiO2 in parallel with the amount of coke formed. TiO2 (Degussa P25) and ZrO2 were found to exhibit the best performance as represented by their activity and stability to deactivation. CeO2 and ZrO2 could be regenerated by air calcination to regain their activity. DRIFTS studies of acetic acid adsorption on oxide surfaces found facile exchange between adsorbed bidentate bridging acetate species and gas-phase acetic acid at 130 °C, well below temperature threshold of acid ketonisation, indicating fast equilibration of different forms of surface acetate species in the ketonisation system. At higher temperatures typical for acid ketonisation, in the absence of gas-phase acetic acid, the adsorbed bidentate bridging acetate-d3 species were found to undergo H/D exchange with proton sites on oxide surfaces. This provides experimental evidence supporting the intermediacy of enolate species in acid ketonisation.

AttachmentSize
Confirmation of attendance UKCC2018.pdf137.71 KB
Confirmation of attendance UKCC2019.pdf114.64 KB
Certificate of Participation UKCC2019.pdf237.87 KB