The tar is unavoidably produced as a by-product of biomass conversions. As a result of its complex composition, I can not find a good solvent system for dissolving it as best as I can. The tar contains phenols, aromatics, acids, etcs.
The following information may be useful for your research
Abstract: Tar content in syngas pyrolysis is a serious problem for fuel gas utilization in downstream applications.This paper investigated tar removal, by the two-step function of decomposition and adsorption, from thepyrolysis gas. The temperature of the tar decomposition process was fixed at 800 C both with and without steam, with air as the reforming agent. Both steam and air had a strong influence on the tar decompositionreaction. The reduction of the gravimetric tar mass was 78% in the case of the thermal cracking,whereas, it was in the range of 77–92% in the case of the steam and air forming. Under conditions of tardecomposition, the gravimetric tar mass reduced, while the yield of the combustible gaseous components in the syngas increased. Synchronously, the amount of light tars increased. This should be eliminatedlater by fixed-bed adsorption. Three adsorbents (activated carbon, wood chip, and synthetic porous cordierite)were selected to evaluate the adsorption performance of light tars, especially of condensable tar.Activated carbon showed the best adsorption performance among all light tars, in view of the adsorptioncapacity and breakthrough time. On the other hand, activated carbon decreased the efficiency of the systemdue to its high adsorption performance with non-condensable tar, which is a combustible substancein syngas. Synthetic porous cordierite showed very low adsorption performance with almost all light tars,whereas, wood chip showed a high adsorption performance with condensable tar and low adsorption
performance with non-condensable tar. When compared with other adsorbents, wood chip showed aprominent adsorption selectivity that was suitable for practical use, by minimizing the condensable tarwithout decreasing the efficiency of the system.
Ref:Tar removal from biomass pyrolysis gas in two-step function of decomposition and adsorption
Thana Phuphuakrat *, Tomoaki Namioka , Kunio Yoshikawa
Applied Energy 87 (2010) 2203–2211
www.researchgate.net/...Tar...biomass_pyrolysis.../00b495270dcfb9337.
Acetone may be a choice. Sometimes, We use it to wash away the tar generated in the biomass gasification, and it performs well.
79.9 % of viscous brown residues remaining in our simple slow pyrolysis test rig were removed by rinsing in hexane. However, dark brown tar like deposits still remained believed to be long molecular weight organic compounds (high molecular weight hydrocarbon are known to be insoluble in Hexane [1]).
1. EPA. N-hexane extractable material (hem) for sludge, sediment, and solid samples; 1998.
There are 3 solvents (acetone, dichloromethane, and anisole). Anisole or methoxybenzene is the best. It has a higher boiling point (154 oC) than the other two solvents so it will be more efficient in the Soxhlet extraction for isolating more tar components .
Tar removal is the big challenge in biomass gasification. one way is to increase the temperature which helps a lot
Nizar Matar
Sir,
we have been using dichloromethane for oil and water separation in our experiments. But the issue with tar remained the same. We were not able to separate it, therefore GC-MS showed a large proportion of macromolecules.
For dichloromethane, we used 1:2 ratio of solvent and condensate and mixed it well and leave it for a long while to develop a phase between them. Can we do the same with other solvents (acetone and anisole)?
Dear Azka,
An experiment will provide the best proof. My advice is to start by testing in acetone then moving to the more expensive anisole. Mind you anisole is found in the anise seeds.
You can even move to tests that use solvent mixtures, e.g. acetone/anisole or acetone/DCM. Each time you do a test, new scientific observation is born whether the result is positive or negative.
Dear K Song,
Some researchers have used isopropyl alcohol in the past to remove tar after biomass gasification.
Hope this helps.
Regards,
BBN
Dear Kunlin Song
Try using common solvents like Hexane, petroleum ether, diethyl ether, acetone, cyclohexanes, solvent naphthas, pyridine or phenols. all these solvents have their unique properties, so try using them based on the result you wish to produce from these solvent.
Numerous articles are available explaining the solvency of these chemicals.One related article can be found in link below
https://pubs.acs.org/doi/pdf/10.1021/ie50406a002
All the very best and good luck
Regards,
Goku
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