Selective Hydrogenation of Renewable Methyl Esters of Linseed oil Catalyzed by Platinum Complexes Modified with Trisulfonated Triphenylphosphine in Aqueous Media

Postgraduate Thesis uoadl:1317083 80 Read counter

Unit:
Κατεύθυνση Ομογενής Κατάλυση
Library of the School of Science
Deposit date:
2014-09-05
Year:
2014
Author:
Στάθης Παναγιώτης
Supervisors info:
Γεώργιος Παπαδογιαννάκης Αναπληρωτής Καθηγητής ΕΚΠΑ (Επιβλέπων), Χριστιάνα Μητσοπούλου, Καθηγήτρια ΕΚΠΑ , Μαρίνος Πιτσικάλης Αναπληρωτής Καθηγητής ΕΚΠΑ
Original Title:
Εκλεκτική υδρογόνωση των ανανεώσιμων μεθυλεστέρων του λινελαίου καταλυόμενη από συστήματα του λευκοχρύσου τροποποιημένα με το μετά Νατρίου ‘Αλας της τρισουλφονικής τριφαινυλοφωσφίνης σε υδατικό περιβάλλον
Languages:
Greek
Translated title:
Selective Hydrogenation of Renewable Methyl Esters of Linseed oil Catalyzed by Platinum Complexes Modified with Trisulfonated Triphenylphosphine in Aqueous Media
Summary:
In this thesis we study the selective hydrogenation of polyunsaturated methyl
esters of linseed oil (MELO) to their monounsaturated C18:1 esters with a low
content of trans-C18:1 isomers catalyzed by water soluble platinum catalyst
modified with the sodium salt of trisulfonated triphenylphosphine (tppts) in
aqueous/organic two phase systems. In the Pt/tppts catalyzed selective
hydrogenation of MELO high catalytic activities have been achieved under mild
reaction conditions to afford a turnover frequency (TOF) of 3000 h-1 at a
temperature of 60°C, 30 bar pressure, molar ratios of C=C/Pt=1000 and
tppts/Pt=12 and a concentration of 200 ppm of platinum in water. The product
obtained within five minutes of reaction time contains a very low amount of
0.7% of the undesired trans-C18:1 esters and a relatively high content of 33.6%
of the desired cis-C18:1 compounds which probably could be attributed to the
low isomerization activity of the Pt/tppts catalyst under these conditions in
the aqueous medium. With increasing tppts/Pt molar ratios decreases the
formation of trans-isomers whereas with increasing reaction times and
temperatures increases considerably the content of the trans-C18:1 esters. The
C=C units/Pt molar ratio has a pronounced and highly interesting effect on the
selectivity of the catalyst. The content of the undesired trans-C18:1 esters
decreased from 6.7 to 1.5% with increasing molar ratios of C=C units/Pt from
1000 up to 4000 with a high catalytic activity of TOF= 3730 h-1 at the low
temperature of 80oC.
Pt/tppts complexes are superior catalysts compared with their rhodium and
palladium counterparts regarding the selectivity on the hydrogenation reaction.
Pt/tppts catalysts yield a very low content of trans-C18:1 esters whereas with
the other metals much higher amounts of the trans-isomers were obtained.
Recycling experiments of the Pt/tppts catalyst showed that the catalytic
activity was lower in one consecutive run.
Keywords:
Hydrogenation , Methyl esters of linseed oil, Trans-isomers, Water soluble platinum complexes, Aqueous/organic two phase systems
Index:
No
Number of index pages:
0
Contains images:
Yes
Number of references:
46
Number of pages:
84
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