(191g) Tar Removal From Biosyngas in the Biomass Gasification Process Using Methylpalmitate (biodiesel constituent). Liquid-Liquid Equilibria of Water + Extraction Solvent (methyl palmitate) + Model Molecules of Tar (naphthalene, anthracene, phenanthrene...)

With the depletion of fossil fuel sources as well as the global warming issues, biomass is used as a primary energy potential source. Although biomass is getting an enhanced attention as a renewable energy source, many problems has to be solved in the production plants such as the reduction of the high level of tar present in the syngas. Indeed, tar is undesirable due to various problems associated with condensation, formation of tar aerosols and polymerisation to more complex structures. The objective of this work is to optimize tar removal from aqueous medium, generated by the condensation of the gas resulting from biomass pyrolysis. The elimination of tar is carried out by liquid extraction using biodiesel solvent represented by one its majority components: methylpalmitate. Tar is represented by model molecules: thiophene, pyridine, phenanthrene, anthracene and naphthalene. With this aim, liquid-liquid equilibria water-methylpalmitate-model molecules of tar are studied in order to determine the partition coefficient of tar molecules in the aqueous phase and in the methylpalmitate rich phase. A glass reactor with an internal capacity of 300 mL is used. The cell is equipped with a magnetic stirrer and a double jacket for a circulating fluid to keep the liquid mixture at constant temperature which is controlled to within 0.1 K. The mixtures are vigorously agitated for 8 h in order to obtain equilibrium and then the two phases are left to settle for 6 h. The compositions of the organic phase (thiophene and pyridine) and aqueous phase for all molecules are analyzed by gas chromatography equipped with a flame ionisation detector or mass spectrometry detector. The molar fraction of the solute in the aqueous phase can reach a value of 6.33x10-08 for phenanthrene and 2.58x10-08 for the anthracene. The partition coefficients of the model compounds are determined from solubility data in the temperature range between 308 K and 343 K and at three compositions of solute between 0.5 percent and 5 percent (in mass).

Acknowledgement is expressed to the ANR VeGaz for the financial support.