Estimation of enthalpy of bio-oil vapor and heat required for pyrolysis of biomass

A method is proposed to estimate the enthalpy of bio-oil in the vapor phase, H_bo, as a function of temperature in the range 298.15-1000 K, of which experimental determination has not been done so far. The two equations proposed in this work allow estimation of the standard enthalpy of formation, H_bo,0, and the difference in the enthalpy between 298.15 K and a given temperature, ΔH_bo(T), respectively, only based on the overall C, H, and O contents of crude bio-oil of that N and S contents are lower than 0.5 and 0.1 wt %-daf, respectively. These equations were optimized using thermodynamic data of 290 and 141 organic compounds for H_bo,0, and ΔH_bo(T), respectively. Given the yields of bio-oil, char, and gas, elemental compositions of the bio-oil and char, and chemical composition of the gas, proposed equations predict the heat required for biomass pyrolysis, Q_py(T_py), which is defined as the enthalpy difference between the products at the pyrolysis temperature, T_py, and the biomass at 298.15 K. The predicted Q_py at T_py = 773-823 K for five different types of dry biomass was in the range of 1.1-1.6 MJ kg ^-1.