## 2 Results and Discussion
### Reactivities of Model Bio-Oil Components
Cs\({}_{2.5}\)/K10 was deactivated by hydroxyacetone based on the greatly reduced phenol conversion (2.2%). No hydroxyacetone was detected after reaction. However, small amounts of 3-methyl-2-hydroxycyclopent-2-enone were detected. To further study this issue, neat 1-hydroxyacetone was heated at 100 \({}^{\circ}\)C for 1h over 30% Cs\({}_{2.5}\)/K10 and the products were identified by GC-MS (Table 9) [22]. Propionic acid (43.7%), hydroxyacetone dimers (24.8%) and 2-hydroxy-3-methylcyclopent-2-enone (9.7%) formed, together with about 1.8% of an unknown species. Three carbon \(\alpha\)-hydroxycarbonyl species such as 1-hydroxyacetone (acetol) can undergo enolization and dimerization to yield the structures illustrated in Scheme 5. The keto form of 1-hydroxyacetone exists in equilibrium with its enol, enediol and aldehyde forms. In both neat and concentrated solutions, 1-hydroxyacetone can dimerize generating the cyclic structures (a) and (b). Decomposition of (b) produces propionic acid. Meanwhile, intermolecular aldol condensation reactions of 1-hydroxyacetone and subsequent serial of dehydration reactions occurred generating 3-methyl-2-hydroxycyclopent-2-enone (c) and its isomers. As a consequence of dimerization and aldol condensation, the 1-hydroxyacetone monomers are expected to diminish with time during upgrading. coke or tar on the catalysts [27]. This has been further confirmed by the reaction products identified from GC-MS analysis (Table 8) of the reaction where neat 2-hydroxymethylfuran (2 g) was heated at 100 \({}^{\circ}\)C for or 1h over 30% Cs\({}_{2.5}\)/K10. In addition to the unreacted 2-hydroxymethylfuran, difurfuryl ether (9.4%), 5-furfuryl-furfuryl alcohol (4.9%) and difuran-2-ylmethane (4.8%), together with about 2.6% other compounds were detected in the products [22]. Rapid polymerization of 2-hydroxymethylfuran occurred at 120 \({}^{\circ}\)C via acid-catalyzed electrophilic condensation with the accompanying loss of formaldehyde [18], generating diffurfuryl ether, 5-furfuryl-furfuryl alcohol, difuran-2-ylmethane, _etc._ (Scheme 6). A large number of compounds with hydroxyl groups, particularly, anhydro monosaccharides such as levoglucosan, were derived from pyrolysis of cellulose and hemicellulose components of the pine wood feed during bio-oil production [5]. Anhydro monosaccharides readily hydrate back to monosaccharides when heated with acid and water. Therefore, the effects of d-glucose addition on 1-octene reactions with phenol/water over Cs\({}_{2.5}\)/K10, DX2, A15 and SSA catalysts were studied at 120 \({}^{\circ}\)C for 3 h (Table 8). SSA gives a higher activity than DX2, A15 and Cs\({}_{2.5}\)/K10. Trace amounts \begin{table}
\begin{tabular}{c c c c} \hline
**Added Reagent** & **Catalyst** & **Phenol conversion (\%)** & \({}^{\textbf{4}}\)**Products yield (\%)** \\ \hline Hydroxyacetone & SSA & 64.0 & Methyl cyclopentenolone (0.12) \\  & Cs\({}_{2.5}\)/K10 & 2.2 & Methyl cyclopentenolone, (0.21) \\ \hline
2-Hydroymethylfuran & SSA & 65.0 & UN \({}^{\text{b}}\) (0.18) \\  & Cs\({}_{2.5}\)/K10 & 4.5 & UN \({}^{\text{b}}\) (0.87) \\ \hline D-glucose & SSA & 64.7 & Anhydrousugar \({}^{\text{c}}\) (0.14) \\  & Cs\({}_{2.5}\)/K10 & 3.5 & Anhydrousugar \({}^{\text{c}}\) (0.20) \\  & A15 & 40.5 & octyl formates, 0.28 \\  & DX2 & 41.3 & octyl formates, 0.36 \\ \hline \end{tabular} \({}^{\text{a}}\)Reaction conditions: (120 \({}^{\circ}\)C,3h, catalyst, 0.15 g; 1-octene (10 mmol); phenol (10 mmol); water (10 mmol); hydroxyacetone (1.4 mmol) or 2-hydroxymethylfuran (1.0 mmol) or d-glucose (0.6 mmol)); \({}^{\text{b}}\) Unknown compound; \({}^{\text{c}}\) Anhydrousugar: 1,6-Anhydro-3,4-dideoxy-\(\beta\)-d-manno-hexapyranose; \({}^{\text{d}}\) GC area\% of involved compounds _versus_ the sum of the GC area\% of all products remained after the reaction.  
\end{table} 
Table 8: Phenol conversions and yields of new products derived from the added reagent (2-hydroxymethylfuran or hydroxyacetone or d-glucose) in 1-octene reactions with water/phenol \({}^{\text{a}}\).