KN DODH Biorefin - Frontiers in Biorefining 2016

KN DODH Biorefin - Frontiers in Biorefining 2016

Rhenium-­‐Catalyzed, Sulfite-­‐
Driven Deoxydehydra9on of Polyols Kenneth Nicholas Department of Chemistry and Biochemistry Deoxydehydra9on of Polyols (DODH) carbohydrates,
polyols
+
Red
CnH2n+2On
LMO2-4
olefins,
unsaturated
alcohols
+
Red-O
+
H2O
CnH2nOn-2
features:
- replace 2 OH with C=C
- produces higher energy product
- requires selective –OH activation/removal
2 Prior Re-­‐Catalyzed Deoxydehydra9on of Diols/Epoxides Cataly6c Diol Deoxydehydra6on (DODH) with PPh3 reductant HO
OH
+ PPh3
R
Cp*ReO3
100 oC
+
R
OPPh3 + H2O
Cp* = Me5C5
Cook and Andrews, J. Am. Chem. Soc. 1996, 118, 9448 K. Gable and B. Ross, ACS Symposium Series, 2006, 921, 143-­‐155 3 Proposed PR3-­‐Driven, Re-­‐Catalyzed DODH Pathway Gable and Andrews 4
Cataly6c Diol DODH with H2 reductant HO
OH
+ H2
R
MeReO3
(4-20 atm) 150
oC
+
R
OPPh3 + H2O
(18-60%)
Abu-­‐Omar et al. Inorg. Chem. 2009, 48, 9998 Cataly6c DODH with alcohol reductant E. Acero, J. Ellman and R. Bergman, J. Am. Chem. Soc. 2010, 132, 11408. 5 More Prac9cal Reductants for Polyol DODH 6
Results and Discussion reac=on screening: methods: -­‐ reac6ons conducted @150 oC in benzene or chlorobenzene (sealed tube) -­‐ stoichiometry: 1.0 glycol/1.2 sulfite/0.05-­‐.10 catalyst -­‐ reac6on mixtures analyzed by GC, GC-­‐MS and H-­‐NMR 7 Substrate, solvent, addi9ve effects on MeReO3 catalysis S. Vkuturi, G. Chapman, I. Ahmad, K.M. Nicholas, Inorg. Chem. 2010, 49, 4744.
8 Competing Side Reactions
R
HO
OH
+ Na2SO3
MeReO3
150 oC
Ph
minor :
major
OH
O
Ph
R
R
+
H
H
O
+
O
Ph
OH
(+ isomers)
acid-catalyzed
9
Na+ ReO4- also catalyzes DODH;
additives enhance conversion rate
C6H11
HO
OH
+ Na2SO3
Na+ ReO4-
C6H11
+ Na2SO4 +
150 oC
H2O
Conversion %
100
80
60
NaReO4
NaReO4+ 15-C-5
NaReO4+ 15-C-5 + 2Na
SO4
40
20
0
10
20
30
40
50
60
70
80
90 100
time (h)
10
Substrate, catalyst effects on Z+ReO4- DODH
R
HO
Substrate
Ph
HO
OH
HO
OH
OH
+ Na2SO3
ZReOx
R
150 oC
+ Na2SO4 +
Catalyst
t (h)
Conv.b
%
Yield
%
NaReO4
NH4ReO4
Bu4NReO4
Re2O7
40
12
59
63
100
100
100
80
53
34
71
23
NaReO4
NH4ReO4
Bu4NReO4
42
26
100
98
100
100
38
37
68
H2O
Major product
Ph
11
Substrate, catalyst effects on Z+ReO4- DODH
R
HO
Substrate
C8H17
HO
Bu4N+ReO4-
R
150 oC
+ Na2SO4 +
H2O
Catalyst
t (h)
% Conv.
% Yield
Major
product
MeReO3
Bu4NReO4
45
110
100
100
80
70
C8H17
MeReO3
Bu4NReO4
67
110
99
100
60
89
C12H25
OH
C12H25
HO
OH
+ Na2SO3
OH
12
Solvent-free DODH
OH
OH +
C6H11
Na2SO3
(xs)
OH
OH +
Ph
Na2SO3
(xs)
OH
HO
OH +
(xs)
Na2SO3
MeReO3
150 oC
sealed tube
C6H11
+ H2O
60%
NaReO4
150 oC
distil
NaReO4
150
Ph
58 %
HO
oC
distil
+ H2O
+ H2O
10-20 %
13
Sulfite and Ligands Effects on MeReO3-Catalyzed DODH
R
HO
OH
+ Na2SO3
MeReO3
L
150 oC
(R= C6H11)
R
+ Na2SO4 +
Entry Ligand Red. 1 -­‐ Na2SO3 2 -­‐ (NH4)2SO3 3 pyridine 4 H2O
% conv. % yield 100 50 Na2SO3 20 10 pyridine (NH4)2SO3 98 62 5 4-­‐methylpyridine " 90 34 6 4-­‐Me2N-­‐pyridine " 53 25 7 4-­‐cyanopyridine " 99 50 8 pyrazine " 99 57 9 (i-­‐Pr)2NEt " 85 58 14
Ligand Effects on Bu4NReO4-catalyzed DODH
R
HO
+ Na2SO3
OH
Bu4N+ReO4-
R
L
150 oC
(R= Ph)
+ Na2SO4 +
H2O
Entry
Ligand
Substrate
Time (h)
%
Conv.
% Yield
1
-
octanediol
100
100
68
2
pyridine
octanediol
293
100
69
3
bipyridine
octanediol
267
100
56
4
2,6-dimethylpyridine
octanediol
125
100
66
5
-
styrenediol
59
100
71
6
2,6-dimethylpyridine
styrenediol
65
100
60
7
pyridine N-oxide
styrenediol
40
~90
31
8
triphenylphosphine
oxide
styrenediol
40
~85
38
15
Probable Catalytic Pathways
path A
path B
SO32-
Z
HO
Re
O
O
O
1
SO42-
ethers,
RCH2CHO
R
Re
O
4
Z
OH
O
R
H2O
Re V
O
O
3
R
O Re O
O
O
2
R
comments: -­‐ the viability of both paths A and B have been demonstrated, e.g.: H2O
O
VII
V
HO
- H2O
Z
Z
O
OH
VII
O
+
R
SO32SO42Z = Me, Ar, Cp*, O-
H
H
H
-­‐ MeReO3 (1) forms glycolate complex 2 at rt (Keq=0.2 with R=Ph); hea6ng 2 with sulfite produces styrene (via path A). -­‐ Hea6ng 1 with sulfite first produces a precipitate (possibly MeReO2 4); hea6ng "4" with glycol (R=Ph) produces styrene (via path B) R
16
Take Home Lessons and Plans
* The first cataly6c deoxydehydra6on processes employing sulfite as the reductant have been discovered. * Commercial MeReO3 and Z+ReO4-­‐ are effec6ve catalysts for the glycol to olefin conversion. * Efforts are underway:
- to extend DODH to biomass polyols such as glycerol and carbohydrates
- to identify the catalytic mechanisms
- to improve the catalytic activity and efficiency via new catalysts and
reductants
17
Garry Chapman
Dr. Irshad Ahmad
18
Acknowledgements
Dr. Saidi Vkuturi Garry Chapman Dr. Irshad Ahmad $
Oklahoma Bioenergy Center (OBC) and the NSF-­‐EPSCOR Cellulosic Bioenergy Program 19