(111f) Separation of Torrefaction Bio-Oils Using Ammonia

In order to decrease overall carbon emissions, biomass related fuels have developed a renewed interest. One option is to combust biomass, however in order to allow for use in current electricity generating systems, pretreatment is required. Raw biomass contains water and other non-preferable chemicals for combustion which can be removed using torrefaction or pyrolysis. The resulting bio-oils create other issues, though, as their large water content and acid content make storage and combustion a problem¹. Our process uses ammonia to create usable mixtures for these bio-oils. Here, ammonia is bubbled through the liquid, which dissolves in the water and neutralizes the acidic components, before separating the bio-oil into an aqueous phase and non-aqueous phase. This was tested on a model bio-oil first, and the water based layer contained a relatively pure solution of ammonium acetate. The organic phase, however, contained many heterocyclic compounds, making usage as a feedstock difficult. This bio-crude was easily combustible, with a heating value slightly higher than ethanol. This process was then repeated using wood pellets as a feedstock for the bio-oil. Separation occurred once again with the aqueous phase being tested as a possible fertilizer, in an attempt to close a loop of nutrients for plant growth and usage as an energy source. The organic phase contained mostly long chain compounds, and cracking of this bio-crude was conducted using H-ZSM 5 catalysts. This was tested over a number of conditions and yielded a mixture of benzene, toluene, xylenes, acetonitrile, furan derivatives and phenol derivatives, which could be used as a fuel. Overall this process was shown to create value added products from a previously unusable chemical mix.

1. Yang, H; et al. Overview of Upgrading of Pyrolysis Oil of Biomass. Energy Procedia. 2014, 61, 1306-1309.