SUSTAINABLE BIOMASS
CONVERSION: CONVERSION OF
CARBOHYDRATES TO PLATFORM
MOLECULES IN DMSO AND GVL
QI LONG
DOCTOR OF PHILOSOPHY
CITY UNIVERSITY OF HONG KONG
JANUARY 2013
CITY UNIVERSITY OF HONG KONG
香港城市大學
Sustainable Biomass Conversion: Conversion
of Carbohydrates to Platform Molecules in
DMSO and GVL
可持續生物質轉化：
碳水化合物在二甲亞碸和γ-戊內酯溶劑中
轉化為綠色合成原料的研究
Submitted to
Department of Biology and Chemistry
生物化學系
in Partial Fulfillment of the Requirements
for the Degree of Doctor of Philosophy
哲學博士學位
By
Qi Long
亓龍
January 2013
二零一三年一月
I
Abstract
Replacement of depleting non-renewable fossil resources with sustainable and
greener substitutes is one of the most important challenges of contemporary research
and development in chemistry and chemical engineering. γ-Valerolactone (GVL) has
been previously suggested as a sustainable liquid for the production of transportation
fuels and carbon-based chemicals. GVL is renewable as it can be produced by four
consecutive reactions from carbohydrates: the acid catalyzed dehydration of fructose,
glucose, sucrose, starch, or cellulose to 5-hydroxymethylfurfural (HMF), the acid
catalyzed hydration of HMF to levulinic acid (LA) and formic acid (FA), the catalytic
hydrogenation of LA to 4-hydroxyvaleric acid (4-HVA), followed by the ring closure
of 4-HVA by dehydration to GVL. Catalytic transfer hydrogenation of LA with FA to
4-HVA is a particularly attractive approach as the overall process of converting
carbohydrates to GVL becomes independent of hydrogen gas and readily useable even
in remote parts of the world.
Mechanistic studies on the conversion of fructose, glucose, and sucrose to HMF
and/or to LA and FA have been performed by the use of 13C- and deuterium-labeled
carbohydrates in both DMSO and GVL. Several intermediates and different reaction
paths were identified and confirmed in the acid catalyzed conversion reactions of
fructose to HMF in DMSO. The irreversibility of reaction routes from the
fructofuranosyl oxocarbenium ion to HMF and the similar pyranose path was
determined by structural information combined with isotopic-labeling experiments.
GVL was successfully used as a green solvent for all steps, demonstrating many
advantages including full compatibility, easy separation, and enhanced productivity.
Reaction conditions including initial fructose concentration, acid concentration,
II
reaction temperature, GVL amount, and different starting carbohydrates were
optimized in GVL. The best yield of LA from carbohydrates was 70%, achieved by
using 2 mmol fructose, 1.5 mL 5 mol/L sulfuric acid, and 10 mL GVL at 130 °C for 2
hours. After optimization the yield of LA starting from HMF was nearly 90% at 5
mol/L H2SO4 in GVL. A similar HMF yield (80%) was reached at the same H2SO4
concentration in DMSO, but further conversion to LA was much slower with poorer
yields.
Several solid acid catalysts (MCM-41 anchored sulfonic acid, cesium salts of
heteropoly acids, supported WO3 and MoO3, etc.) have been synthesized and tested
for the HMF production from fructose in DMSO. The use of MCM-41 anchored
sulfonic acid and the salt Cs3HPW12O40 resulted in the full conversion of fructose and
about 80% yield of HMF. These catalysts were better than the commercially available
Brønsted acidic solid catalysts such as BETA zeolite and Nafion resins.
The one pot conversion of fructose to GVL in GVL as the solvent has been
carried out using
13
C6-fructose as the starting material and H2SO4 (5 mol/L) as the
catalyst at 130 °C. The formation of
13
C6-HMF by the dehydration of
13
C6-fructose
was followed by its hydration to 13C5-LA and 13C-FA. The Shvo-catalyst was added to
the reaction mixture when the conversion to LA and FA was highest, to achieve the
subsequent conversion to
13
C5-GVL at 100 °C in two hours.
were used to confirm the formation of 13C5-GVL in GVL.
13
C NMR and GC-MS
V
Table of Contents
ABSTRACT ........................................................................................................................................... I
ACKNOWLEDGEMENTS .....................................................................................................................III
DECLARATION .................................................................................................................................. IV
TABLE OF CONTENTS ......................................................................................................................... V
LIST OF FIGURES ................................................................................................................................IX
LIST OF TABLES ................................................................................................................................ XV
LIST OF SCHEMES ........................................................................................................................... XVI
CHAPTER 1.
INTRODUCTION ........................................................................................................... 1
1.1
SUSTAINABLE CARBOHYDRATE BASED BIOMASS CONVERSION TO PLATFORM MOLECULES ............................... 1
1.2
CARBOHYDRATES AND THEIR CHARACTERISTICS ..................................................................................... 3
1.3
PLATFORM MOLECULES AND THEIR DERIVATIVES.................................................................................... 6
1.4
LITERATURE SURVEY ON MECHANISMS FOR THE CONVERSION OF SUGARS TO HMF AND HMF TO LA & FA ...... 9
1.4.1
Conversions of Sugars to HMF .......................................................................................... 9
1.4.2
Conversion of HMF to LA and FA .................................................................................... 13
1.4.3
Side reactions and preventions....................................................................................... 14
1.5
HOMOGENEOUS CATALYSTS ............................................................................................................ 17
1.6
HETEROGENEOUS CATALYSTS........................................................................................................... 17
1.7
SOLVENT EFFECTS ON BIOMASS CONVERSION AND DECOMPOSITION OF DMSO ......................................... 20
1.8
AIMS OF RESEARCH ....................................................................................................................... 23
VI
CHAPTER 2.
CONVERSION OF CARBOHYDRATES TO HMF ............................................................. 25
2.1
HMF PRODUCTION IN DIFFERENT SOLVENTS FROM FRUCTOSE ................................................................ 25
2.2
HMF PRODUCTION OPTIMIZATION IN DMSO .................................................................................... 26
2.3
MECHANISM OF THE CONVERSION OF FRUCTOSE TO HMF IN DMSO ...................................................... 29
2.4
HMF PRODUCTION OPTIMIZATION IN GVL ........................................................................................ 39
2.5
FRUCTOSE AND GLUCOSE CONVERSION MECHANISM STUDIES IN GVL ...................................................... 45
2.6
SOLID CATALYST DESIGN AND SYNTHESIS ............................................................................................ 48
2.6.1
Heteropoly acids for the conversion of fructose with high yields ................................... 49
2.6.2
Heteropoly acids heterogenization................................................................................. 52
2.6.3
Supported metal oxides: W/Mo on γ-Al2O3 .................................................................... 54
2.6.4
MCM-41 anchored sulfonic acid ..................................................................................... 55
CHAPTER 3.
CATALYTIC CONVERSION OF CARBOHYDRATES OR HMF TO LA AND FA .................... 56
3.1
LA AND FA PRODUCTION OPTIMIZATION IN GVL ................................................................................. 56
3.2
LA AND FA PRODUCTION FROM HMF IN GVL .................................................................................... 66
3.3
LA AND FA PRODUCTION FROM HMF IN DMSO ................................................................................ 68
3.4
HMF HYDRATION TO LA AND FA MECHANISM STUDIES IN DMSO AND IN GVL ........................................ 70
CHAPTER 4.
CATALYTIC CONVERSION OF FRUCTOSE TO GVL IN GVL............................................. 73
4.1
THE SUPERIORITY OF GVL AS A SUSTAINABLE LIQUID ............................................................................ 73
4.2
ONE POT CONVERSION OF FRUCTOSE TO GVL ..................................................................................... 75
CHAPTER 5.
EXPERIMENTAL ......................................................................................................... 82
VII
5.1
INSTRUMENTATION ....................................................................................................................... 82
5.2
CHEMICALS .................................................................................................................................. 82
5.3
GENERAL ANALYTICAL PROTOCOLS ................................................................................................... 83
5.4
DETAILS ...................................................................................................................................... 86
5.4.1
Fructose dehydration in different solvents ..................................................................... 86
5.4.2
Fructose dehydration in DMSO at different sulfuric acid concentration ........................ 86
5.4.3
HMF production in DMSO with different carbohydrate substrates ................................ 86
5.4.4
LA production from HMF in DMSO at different sulfuric acid concentration ................... 87
5.4.5
Mechanistic studies of fructose conversion in DMSO ..................................................... 87
5.4.6
Mechanistic studies of HMF conversion to LA and FA in DMSO ..................................... 88
5.4.7
Fructose dehydration in GVL at different sulfuric acid concentration ............................ 88
5.4.8
Fructose dehydration in GVL at different temperature .................................................. 89
5.4.9
Fructose dehydration with different initial fructose concentration in GVL .................... 89
5.4.10
Fructose dehydration with different GVL amount ..................................................... 90
5.4.11
Carbohydrate dehydration in GVL with different starting materials ......................... 90
5.4.12
HMF conversion to LA and FA in GVL at different sulfuric acid concentration .......... 91
5.4.13
Fructose and glucose dehydration mechanism studies in GVL .................................. 91
5.4.14
HMF dehydration at reduced pressure with homogeneous heteropoly acids ........... 91
5.4.15
Supported WO3 and MoO3 on γ-Al2O3........................................................................ 92
5.4.16
Synthesis of cesium salts of heteropoly acids, Cs3HSiW12O40 and Cs2.5H0.5PW12O40 ... 92
VIII
5.4.17
Synthesis of heteropoly anions salts with large surfactant cations ........................... 93
5.4.18
Synthesis of MCM-41 anchored sulfonic acid (MCM-41-SO3H) ................................. 93
5.4.19
2,6–Anhydro-β-D-fructofuranose (2,6-AF) synthesis ................................................. 93
5.4.20
13
CHAPTER 6.
C-labeled HMF synthesis and purification ............................................................... 95
CONCLUSIONS ........................................................................................................... 97
APPENDIX ........................................................................................................................................ 99
PUBLICATION LIST BY DECEMBER 2012 .......................................................................................... 105
REFERENCES ................................................................................................................................... 105