Liquid Product of Liquid Phase Pyrolysis

Ligno-cellulosic feed is expected to contribute significantly to production of liquefied combustibles in the future, because of the quantity and the variety of feed material. Therefore the pyrolytic degradation properties of wood and its building blocks glucose and cellulose were investigated.

The process was carried out in a semi-batch reaction vessel under isothermal conditions at a temperature of T = 623 K and at ambient pressure. For optimum heat transfer the pyrolysis process was carried out in liquid carrier phase. Gaseous as well as condensable products were removed on top of the reaction vessel. Condensation temperature was T = 20 °C. After recording flux and composition the gaseous phase was incinerated in a flare. The condensed products were analyzed by GC-MS and NMR spectroscopy as well as elementary analysis.

The product yield was determined. Liquid CHO-products and water formed during pyrolytic degradation were evaluated for several feed materials. All biomasses generate nearly the same amount of liquid CHO-products, while the water quantity differs. Because of lignin content wood generates the least water fraction, whereas the mono-sugar glucose shows a high tendency of water formation.

The yield was examined for selected products generated by liquid-phase pyrolysis. Wood, with about 40% cellulose, shows different reaction paths than cellulose and glucose monomer. Degradation of cellulose is seemingly controlled by cleavage plus dehydration, while ligno-cellulosic feed leads to formation of methoxy-substituted phenols. Moreover wood degrades to acetic acid, whereas cellulose and glucose forms just traces of it.