Effect of Pinus radiata Bark Polyphenols on Phenol Liquefaction of Cellulose in the Presence of p-Toluene Sulfonic Acid Catalyst

The influence of Pinus radiata bark polyphenol components in the phenol liquefaction of P. radiata bark was investigated using p-toluene sulfonic acid (PTSA) and sulfuric acid (SA) as acid catalysts. A series of the phenol liquefaction reactions were carried out using mixtures of pure cellulose with increasing amounts of hot-water extract (HWE) of P. radiata bark-the polyphenol-rich component of bark. The yields of liquefied product reactions and combined phenol amounts in them were determined, and the liquefaction residues were also analyzed for determination of acid-soluble and insoluble polyphenols and residual cellulose fractions. The yield of cellulose liquefaction decreased linearly with increasing amounts of HWE with the effect being more pronounced for SA than for PTSA. The combined phenol amount increased with liquefaction yield increases for both SA and PTSA catalysts, but at liquefaction yield levels above 83 percent, more phenol was combined for SA catalyst than for PTSA catalyst. The liquefaction residues contained lower cellulose and higher polyphenol components for SA catalyst than for PTSA catalyst at the same liquefaction time. The results indicate that the bark polyphenol components can significantly interfere in the acid-catalyzed bark phenol liquefaction reactions by their excessive condensation with cellulose and/or phenol, especially in the presence of SA catalyst.