BENEFICIAL-EFFECTS OF HYDROGEN PRESSURE IN THE PYROLYSIS OF BIOMASS -A STUDY OF EUPHORBIA-RIGIDA

Fixed-bed pyrolysis and hydropyrolysis experiments at different temper atures and pressures have been conducted on a sample of Euphorbia Rigi da extracted with n-hexane and methanol to remove low molecular mass t erpenoids and saccharides to elucidate the extent of oil formation fro m the remaining predominantly cellulosic structure. The trends in yiel d and product composition are markedly different to those found previo usly for coals. Primary oil yields reached a maximum of ca 35% (daf ba sis corresponding to ca 60% on a carbon basis) at a hydrogen pressure of 50 bar and 500 degrees C. Raising the temperature and hydrogen pres sure decreased the oxygen contents and increased the aromaticities of the oils but also increased hydrocarbon gas yields. The relatively hig h nitrogen contents of the oils (2-3%) were not markedly affected by h ydrogen pressure and present the major obstacle to producing Light hyd rocarbon oils via two-stage hydropyrolysis.