Mark Rüsch gen. Klaas, Jan Zawerucha, Juliane Schneider and Paul Rakowski

Transcription

1 Mark Rüsch gen. Klaas, Jan Zawerucha, Juliane Schneider and Paul Rakowski Chemistry of Renewables Faculty of Technology University of Applied Sciences Emden -Leer Workshop on Glycerol Marketing Uses and Chemisty, Milano, ctober 19, 2012

2 Incentives to Utilize Glycerol additional production of glycerol as a byproduct of biodiesel; future unknown additional production is far bigger than the traditional market for glycerol dramatic variation in prices (crude) low added value usage: feed, fuel, biogas new routes to C 3 commodities: 1,2-propylen glycol, 1,3-propylen glycol, epichlorhydrin other derivatives with higher added value and less dependency on crude glycerol price

3 Glycerol Formal H H H H + C H - H 2 H + H 60 % 40 % condensation of glycerol with formaldehyde mixture of isomers: 60 % 5-Hydroxy-1,3-dioxiran ( secondary glycerol formal ) 40 % 4-Methylhydroxy-1,3-dioxolan ( primary glycerol formal )

4 Lipase-catalyzed selective esterification of glycrol formal: The idea H H + C 11 H 23 C R H [1,3-selective lipase] - RH C 11 H 23 C selective esterification of the primary glycerol formal with a fatty acid (derivative) separation of the unreacted secondary glycerol formal and the ester

5 Lipase-catalyzed selective esterification of glycerol formal: Variations H Esterification: + C 11 H 23 C H [1,3-selective lipase] C 11 H 23 C + H 2 H Transsterification: + C 11 H 23 C CH 3 [1,3-selective lipase] C 11 H 23 C + CH 3 H H Irreversible Esterification: + C 11 H 23 C CH=CH 2 [1,3-selective lipase] C 11 H 23 C + CH 3 CH

6 Lipase-catalyzed esterification of glycrol formal: Unexpected results H C 11 H 23 C 0 + C 11 H 23 C R H [lipase] - RH C 11 H 23 C GC: instead of two products two pairs of products (HP Innowax 91091N)

7 Lipase-catalyzed esterification of glycrol formal: Unexpected results GC: instead of two products two pairs of products each pair has identical mass spectra each pair has very similar IR, but slightly different C= bands rare example of GC stable 5 and 6 ring diastereomeres (substituted 1,3-dioxans and 1,3- dioxolanes) (Schowler and Darley, Chem. Rev. 1966)

8 Starting conditions for the screening glycerol formal mixture 60 : 40 glycerol formal / acyl donor = 5 / 2 lauric acid / methylester / vinylester glycerol formal concentration: 0.25 M (in MTBE) enzyme load: 0.02 mol acyl donor / g enzyme reaction temperature 40 o C reaction time 72 h selectivity is expressed as the relative amount of primary ester to secondary ester: = 0.66 means no selectivity > 0.66 means preference for the primary ester conversion is acyl donor conversion

9 conversion % Enzyme Screening

10 selectivity 1,2 / 1,3 Enzyme Screening

11 Enzyme Screening selectivity 1,2 / 1,3 Rhizomucor miehei (Palatase ) is the only active and selective one

12 conversion (R.miehei) % Solvent Screening

13 selectivity 1,2 / 1,3 (R. miehei) Solvent Screening

14 Solvent Screening selectivity 1,2 / 1,3 (R. miehei) highly selective at about 60 % conversion

15 Conversion (R.miehei) % Enzyme Load t-buh 2-M-2-B mol acyl donor / g enzyme

16 Selectivity (R.miehei) % Enzyme Load t-buh 2-M-2-B mol acyl donor / g enzyme

17 Esterification Conversion (R.miehei) % Selectivity (R.miehei)

18 Substrate Concentration Conversion % Selectivity t-buh 2-M-2-B t-buh 2-M-2-B Glycerol formal concentration (M)

19 Established reaction conditions glycerol formal mixture 60 : 40 glycerol formal / methyl ester = 5 / 2 glycerol formal concentration: 0.25 M solvent: 2-Methyl-2-Butanol Rhizomucor miehei (Palatase 20,000L by Novo) enzyme load: 0.01 mol acyl donor / g enzyme reaction temperature 40 o C reaction time 72 h selectivity > 31 ( 97 % ) at 60 % conversion

20 ther Esters Conversion (R.miehei) % Selectivity (R.miehei) Results for C 7:0, C 16:0, C 18:0 are uncorrected GC values

21 Preparative results the 4-Methylhydroxy-1,3-Dioxolane laurate can be obtained by short-path destillation with 23 % preparative yield and 96 % purity the 4-Methylhydroxy-1,3-Dioxolane stearate precipitates from the solution at 0 o C with 20 % preparative yield and 94 % purity impurites are the 5-Hydroxy-1,3-dioxiran esters yields are based on glycerol formal (yields of % based on the methyl esters)

22 Stability of the isomers any glycerol formal mixture isomerizes to the 60 : 40 mixture - in weeks - in hours in solution, at elevated temperatures and / or in the presence of formaldehyde although we obtain an enriched 5-Hydroxy-1,3-dioxirane, it is of limited use the 4-Methylhydroxy-1,3-Dioxolane esters do not isomerize in substance have enough stability for short path destillation

23 Two-Step-Process add consumed ester / glycerol formal Esterification (20-25 % conversion of glycerol formal) Isomerization of glycerol formal (during short-path destillation) pure 4-Methylhydroxy- 1,3-dioxolane ester

24 Two-Step-Process add consumed ester / glycerol formal Esterification (20-25 % conversion of glycerol formal) Isomerization of glycerol formal (during short-path destillation) add spent enzyme pure 4-Methylhydroxy- 1,3-dioxolane ester

25 Two-Step-Process add consumed ester / glycerol formal Esterification (20-25 % conversion of glycerol formal) Isomerization of glycerol formal (during short-path destillation) add spent enzyme no enzyme recycling with Palatase pure 4-Methylhydroxy- 1,3-dioxolane ester

26 The use of an immobilied form of Rhizomucur mihei (RM-IM ) does not give acceptable selectivities! Why does immobilization change the selectivity dramatically?

27 Glycerol formal is an attractive derivative of glycerol for high value added applications if and only if the isomers can be used separately Although we are not able to isolate the glycerol formal isomers, we can produce pure 4-Methylhydroxy-1,3-dioxolane ester (primary glycerol formal esters) and indirectly pure 1-glycerol esters via 1,3-selektive esterification The enzyme used is cheap but so far there is no enzyme recycling. The change of selectivity that accompanies the immobilization of the enzyme is not understood.