Thermodynamic and Physical Property Estimation of Compounds Derived from the Fast Pyrolysis of Lignocellulosic Materials

Abstract

The development of biomass pyrolysis oil refineries is a very promising path for the production of biofuels and bioproducts from lignocellulosic materials. Given that bio-oil is a complex mixture of organic compounds, the production of valuable bioproducts may imply the use of different separation processes, such as distillation, selective condensation, crystallization based on melting points, liquid−liquid extraction or adsorption, and/or upgrading treatments, such as catalytic cracking or hydrodeoxygenation. In this context, the main objectives of this work are (1) to propose a simple but representative composition of the bio-oil, which can be used as a bio-oil surrogate, and (2) to determine selected thermodynamic, physical, and molecular properties of the organic compounds included in the bio-oil surrogate using different estimation methods and calculation procedures. These properties are critical temperature, critical pressure, critical volume, normal boiling point, enthalpy of vaporization, vapor pressure curves, normal melting point, enthalpy of fusion, heat capacities of gas, liquid, and solid, gas and liquid standard enthalpy of formation, gas standard Gibbs free energy of formation, Hansen solubility parameters, molecular volume, and molecular diameter. This group of properties has been selected for their possible application in the simulation or design of thermochemical, separation, and upgrading processes. Additionally, the suitability of the estimated thermodynamic properties and the proposed surrogate composition has been assessed by comparing experimental and literature data with the apparent enthalpy of formation of the bio-oil predicted from the weight-averaged contributions of the compounds as well as the heat required for the pyrolysis process at 500 °C.

Contributions of Thermal Ejection and Evaporation to the Formation of Condensable Volatiles during Cellulose Pyrolysis

“…Biomass pyrolysis, as a promising process for producing renewable bio-oil and biochemicals, has received tremendous attention over the past decades. − Despite a high yield (60–70 wt.%) of bio-oil from biomass fast pyrolysis, bio-oil suffers from poor quality including high water content, high acidity, high viscosity, and phase instability, which has largely hindered the commercialization of bio-oil production. − It is known that the bio-oil quality is largely determined by the composition of condensable volatiles generated during biomass pyrolysis . To develop novel technologies to produce a high-quality bio-oil, it is of critical importance to understand the formation mechanisms of condensable volatiles from biomass fast pyrolysis.…”

“…5−7 It is known that the bio-oil quality is largely determined by the composition of condensable volatiles generated during biomass pyrolysis. 8 To develop novel technologies to produce a highquality bio-oil, it is of critical importance to understand the formation mechanisms of condensable volatiles from biomass fast pyrolysis.…”

Estimation of the heat required for intermediate pyrolysis of biomass

“…These results have demonstrated that the heat required for pyrolysis was dependent on the type of feedstock. For the three biomass wastes, Q py for intermediate pyrolysis was slightly lower than for fast pyrolysis of forestry biomass at the same temperature (Fonts et al 2021). The heat required for pyrolysis of biomass waste was also compared to the higher heating value intrinsically contained in the feedstock, here the Q py values have ranged from 4.1-10.4% of higher heating value of the dry feedstock was missing to achieve self-sustaining energy of the pyrolysis process.…”

“…An extra heat transfer to the carrier gas, i.e. nitrogen, in the order of 1.6 MJ/kg feedstock has to be considered (Fonts et al 2021). Including the heating of nitrogen used as a carrier gas, the total heat required for fast pyrolysis was 3 MJ/kg.…”

2021 Pioneers in Energy Research: Javier Bilbao

“…Pujro et al 28 have reviewed the various catalytic reactions involved during pyrolysis oil upgrading, with a special emphasis on the transfer of hydrogen, for deoxygenation, which can be potentially donated "in situ" by the molecules (such as alcohols) present in the bio-oils. Fonts et al 29 have proposed a simple but representative composition of a biomass pyrolysis oil, which can be used as a bio-oil surrogate. Then, they have determined selected thermodynamic, physical, and molecular properties of the organic compounds included in the bio-oil surrogate.…”