Solubility of Major Producer Gas Tar Compounds in Water

Wet scrubbing process removes producer gas impurities such as tars and particulates. Water is the most common scrubbing solvent in biomass producer gas applications. Major tar compounds in biomass-based producer gas include benzene, toluene, ethyl benzene, styrene, m-xylene, and naphthalene. Solubility, which is defined as the fraction of a selected solute in a selected solvent, is one of the crucial parameters for designing the wet scrubbing columns. The primary goal of this study is to develop a solubility model to generate theoretical data in Aspen Plus. Using this software package, water solubility data for these selected producer gas tar compounds under varying operating temperatures is determined. It was determined the solubility (g/100ml) of benzene, toluene, ethyl benzene, styrene, m-xylene, and naphthalene varies in the range of 0.16-0.26, 0.032-0.062, 0.015-0.023, 0.016-0.043, 0.0075-0.019, and 0.004-0.0067, respectively as the temperature increases from 5°C to 70°C. Results show that all tar compounds have poor water solubility and are significantly affected by operating temperature. These data are in close agreement with those values published in NIST-IUPAC and DECHEMA databases. Using this knowledge, solvent-water mixtures will be selected and explored to develop a low-cost producer gas wet scrubbing system.