Fractionation of Bio-Oil

Abstract

The fuel properties of fast pyrolysis bio-oils differ significantly from those of fossil fuels. As transportation fuel, bio-oil is not suitable without upgrading because of its relatively low energy content, high water content, acidity, and poor storage stability. Upgrading of bio-oil has usually been done by treating the whole oil in a reactor. The problem with this treatment is that pyrolysis oil is a mixture of different compound groups, which all need different conditions and catalysts to react in a desirable way. Therefore, an efficient fractionation of bio-oil before upgrading may be a more efficient way of producing liquid fuels than treating the whole oil. In this work, the target was to compare two industrially relevant fractionation concepts. In the first concept, most of the water was removed during liquid recovery by adjusting the scrubber temperature. When the scrubber temperature was increased from 36 to 66 °C, the water content in the bio-oil decreased from 24 to 7 wt %. In the second concept, fast pyrolysis was carried out with wet feedstock. This would reduce the drying cost in the plant. By this means, a spontaneous phase separation was generated after liquid condensation. In the experiments, the moisture content of the raw material was increased up to 25 wt %, but even with this moisture content, the oily bottom phase still contained 22 wt % watersoluble compounds. However, if the target is to produce transportation fuels from bio-oil, fractionation by phase separation is a better concept for dividing the bio-oil into different compound groups.

Hydrocarbon Liquid Production via Catalytic Hydroprocessing of Phenolic Oils Fractionated from Fast Pyrolysis of Red Oak and Corn Stover

“…7 Effective bio-oil fractionation prior to upgrading may be a valuable approach of producing liquid fuels and chemicals versus upgrading whole bio-oil. 2,8 Iowa State University has developed a fractionating bio-oil recovery system that allows for collection of bio-oil as heavy-ends (stage fraction (SF) 1 and SF 2), intermediate fractions (SF 3 and SF 4), consisting of monomeric compounds, and light ends (SF 5) that contain the majority of acids and water ( Figure 1). 9,10 Complete details on the reactor and recovery system can be found in Pollard et al 9 and Rover et al 10 The mass distribution (wet basis) when using red oak feedstock is approximately 40− 45 wt % for SF 1 and SF 2 heavy ends, 10 wt % for SF 3 and SF 4 intermediates, and 45−50 wt % of SF 5 light ends.…”

Steam reforming of pyrolysis oil aqueous fraction obtained by one-step fractional condensation

“…Because this feedstock was used in the steam reforming experiments without any additional water, the subsequent S/C ratio was calculated to be 3.84. Aqueous pyrolysis oil obtained via water-induced phase separation has been shown to contain sugar-type compounds and light organics in a ratio of 3:1 [24]. Compared to this, the aqueous fraction that has been characterized and used in this study contained a clearly lower amount of sugar-type compounds.…”

“…The feedstock for the pyrolysis experiment was forest thinnings, and the pyrolysis was carried out at a temperature of 480 C. Fractional condensation of the pyrolysis vapours was achieved by operating the scrubbers at 65 C. The aqueous fraction, which was utilized in this i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y 4 0 ( 2 0 1 5 ) 3 1 4 9 e3 1 5 7 study, was collected after the scrubbers via a secondary condensation system. The fractionation procedure is described in more detail by Lindfors et al [24].…”

“…'sugars' and low molecular weight oxygenates, exhibit different levels of suitability for steam reforming, it stands to reason that simply separating the pyrolysis oil into water-soluble and waterinsoluble fractions via phase separation is by no means an optimal solution. In addition to the solubility-based fractionation procedure which transfers both the sugars and the low molecular weight oxygenates into one single aqueous fraction, it is also possible to fractionate the pyrolysis oil components based on their volatility [23,24]. With this kind of approach, it is possible to manipulate the distribution of different pyrolysis oil components, and to obtain fractions which are enriched in certain products.…”

A Review of Improvements to the Liquid Collection System Used in the Pyrolysis Process for Producing Liquid Smoke

“…(2014) used a sieve-plate column (scrubber) on the pyrolysis vapor to condense it in the first stage of liquid recovery. To condense the vapor generated by the reactor in the first stage, direct and indirect cooling were applied to the liquid from the hot vapor; inlet direct cooling was applied in the sieve-plate column, then the thermal degradation reaction of the collected pyrolysis liquids was reduced (Lindfors et al, 2014). A hydrocarbon liquid was used as the liquid cooler in the scrubber.…”