All reactions were carried out in glass pressure reaction vessels equipped with a magnetic stirrer. The temperature, controlled using an external oil bath, was raised to the desired value (100 °C or 120 °C) and held for the desired time (1 h or 3 h) with vigorous stirring. In a typical reaction, SSA (0.15 g), 1-octene (1.35 g), 1-butanol (0.15 g), phenol (0.94 g), water (0.15

g) , acetic acid (0.15 g), acetaldehyde (0.12 g), hydroxyacetone (0.12 g), D — glucose (0.15 g), 2-hydroxymethylfuran (0.15 g) and the internal standard (99.9% 1-dodecane, 0.02 g) were charged in that order. Catalysts studied included SSA, Cs25/K10, A15, A36 and DX2. After reaction (typically, 3

h) , all products were diluted in methanol and identified by analysis on a Shimadzu QP2010S gas chromatograph equipped with a mass selective detector (GC-MS) using helium as the carrier gas. A SHRXI-5MS (30 m * 0.25 mm I. D. * 0.25 pm film) capillary column was used with a 50:1 split ratio and a solvent cut time of 3 min. The temperature program, started at 30 °C (5 min), was ramped from 30 to 300 °C at 10 °C/min and held at 300 °C for 8 min. An auto-sampler and the same analysis method were used for all product analyses. MS identification of the products was based on molecular mass, fragmentation patterns and by matching the spectra with a digital compound library. The percent phenol conversion to other products in the upgrading reactions was determined by the change in peak area versus that of the 1-dodecane internal standard.

5.4 CONCLUSIONS

Liquid phase supported acid-catalyzed olefin/alcohol reactions with mod­el bio-oils indicate that silica sulfuric acid is an improved catalyst with greater hydrothermal stability and catalytic activity over Cs25/K10 and other resin sulfonic acids. Development and demonstration of this im­proved catalyst meets one goal of this study. Cs25/K10 lost most of its catalytic activity, poisoned by the coke formation from hydroxyacetone,

2- hydroxymethylfuran and D-glucose. Decomposition of resin-bound sul­fonic acids occurred.

The use of different olefins and alcohols leads to different product se — lectivities. This study has demonstrated many of the competing reaction pathways which occur in bio-oil upgrading by acid-catalyzed alcohol/ olefin treatment in much greater detail than all previous work, thereby accomplishing a second major goal of this work. Upgrading bio-oil via simultaneous reactions with olefin/alcohol under acid-catalyzed condi­tions was complex, involving many simultaneous equilibria and compet­ing reactions. These reactions mainly include phenol alkylation, olefin hydration, esterification, etherification, acetal formation, olefin isomeriza­tion and oligomerization, cracking and reoligomerization of tertiary cat­ion centers from protonated olefins and their fragments, hydroxyacetone dimerization (including cyclization) and intermolecular aldol condensa­tion. Also, levulinic acid formation both from sequential dehydration, ring contractions, hydrations and ring opening of monosaccharides, and from sequential rehydration, ring opening, dehydration and tautomerization of 2-hydroxymethylfuran occurred. Synergistic interactions among reactants and products were determined.

somenzation
О efin isomers
Oligomerization
Olefin Oligomers
Olefin
Alcohols
Ethers
R-O-R (RI
-OH
R-O-R ♦ H20
R — C-OR
R-COOH
R-O-R
R — OH	R-O-R
OR* OHR — OH
R — O-R (R) + H20
(‘)R-OH
R*-OH2
RM,-C-OR* ♦ H20
R-COOH
r*-qh|
R — OH
R""
‘RO^H(R…. )
HO OR
Raw ‘ Bio-oil ‘S
R’-OH
о он
ЦПОИ
н2о/н
Hexoses
НОН? С о СНО
но
но. о
V<NOH
о он
он
Bio-oil
FIGURE 2: Reaction pathways of the model bio-oil components during upgrading with olefin/alcohol over solid acid catalysts.

Water removal by acid-catalyzed olefin hydration is the key reason for the success of this upgrading process. As water concentration drops, es­terification and acetal formation equilibria shift toward ester and acetal products. In turn, the formed esters and acetals as well as the added alco­hol help reduce the phase separation present between hydrophilic bio-oil and hydrophobic olefin. All of this occurs while maintaining all the caloric value of both the raw bio-oil and the alcohol and olefin reagents. This work also provides further insight into the complexity of this bio-oil up­grading approach.