Several methods to control the water content of pyrolysis oil from fast pyrolysis of biomass were evaluated experimentally. Parameters varied were the operating temperature of the condenser, the gas load of the condenser, and the moisture content of the feedstock. Experiments were performed in a continuous bench scale plant (1 kg/h intake) equipped with a fluidized bed reactor. Pine wood with moisture contents between 0 wt % and 20 wt % (as-received basis) was used as feedstock. The mass balance closure was between 94 wt % and 102 wt %, and the reproducibility of yields of identical experiments was good. Increasing the condenser temperature (15−90 °C) and increasing the gas load (2.0−4.1 kg of gases/kg of vapors in the condenser feed) of the condenser are both well suited to control the water content. However, decreasing the water content by these measures always results in a loss of organic vapors, leading to a lower oil yield in the condenser. Deep drying of the feedstock is beneficial; a lower moisture content of the feed results in less loss of organic vapors for the same water content of pyrolysis oil. Experimental results were compared with the predictions of an equilibrium flash condensation model. Predictions of this equilibrium model are in good agreement with the experimental results. All input parameters of the model (reactor yields and composition of the organics in pyrolysis oil) can be measured, or are known, with sufficient accuracy.

In this paper, we have investigated the possibilities to steer the composition and, thus, the quality of pyrolysis liquids by the reactor temperature and the pyrolysis vapor condenser temperature. Pine wood was pyrolyzed in a 1 kg/h fluidized-bed pyrolysis reactor operated at 330 or 480°C. The pyrolysis vapors produced were condensed using a condenser train of two countercurrent spray columns arranged in series. In this paper, the temperature of the first condenser was varied between 20 and 115°C, while the second condenser temperature was kept at 20°C. To describe the composition of the oils, we have integrated several analytical techniques into a novel characterization scheme that can account for 77À82 wt % of the oils. The effects of the condensation conditions on fractions of light compounds in the oils can be predicted with a simple equilibrium stage condensation model. It has been observed that pyrolysis at 330°C gives a light oil with a low amount of mid-boilers [normal boiling point (nbp) of 150À300°C] and heavy compounds (water insolubles and mono-and oligosugars). Sugars, mid-boilers, and water-insoluble ligninderived oligomers are more present in the oil obtained at 480°C, while the yields of light organics are approximately the same for 330 and 480°C. It can be concluded that fractional condensation is a promising cheap downstream approach to concentrate compounds (classes) and, thus, to control the quality of pyrolysis oils. For instance, operating the first condenser around 70À90°C gives an aqueous liquid in the second condenser containing 40 wt % light organics, which are interesting for extraction (e.g., 10 wt % acetic acid) and supercritical water gasification to produce hydrogen. Under these conditions, the oils from the first condenser have a high content of sugars (20 wt %) and lignin-derived oligomers (40 wt %), which are attractive fractions for fermentation/sugar chemistry and gasoline production via fluidized catalytic cracking (FCC)/hydrotreatment, respectively.

This paper provides a review on pyrolysis technologies, focusing on reactor designs and companies commercializing this technology. The renewed interest on pyrolysis is driven by the potential to convert lignocellulosic materials into bio-oil and biochar and the use of these intermediates for the production bio-fuels, biochemicals and engineered biochars for environmental services. This review presents slow, intermediate, fast and microwave pyrolysis as complementary technologies that share some commonalities in their designs. While slow pyrolysis technologies (traditional carbonization kilns) use wood trunks to produce char chunks for cooking, fast pyrolysis systems process small particles to maximize bio-oil yield. The realization of the environmental issues associated with the use of carbonization technologies and the technical difficulties to operate fast pyrolysis reactors using sand as heating media and large volumes of carrier gas, as well as the problems to refine resulting highly oxygenated oils, are forcing the thermochemical conversion community to rethink the design and use of these reactors. Intermediate pyrolysis reactors (also known as converters) offer opportunities for the large scale balanced production of char and biooil. The capacity of these reactors to process forest and agricultural wastes without much preprocessing is a clear advantage. Microwave pyrolysis is an option for modular small autonomous devises for solid waste management.

in Wiley Online Library (wileyonlinelibrary.com).To maximize oil yields in the fast pyrolysis of biomass it is generally accepted that vapors need to be rapidly quenched. The influence of the heterogeneous and homogeneous vapor-phase reactions on yields and oil composition were studied using a fluidized-bed reactor. Even high concentrations of mineral low char (till 55 vol %) appeared not to be catalytically active. However, the presence of minerals, either in biomass or added, does influence the yields, especially by the occurrence of vapor-phase charring/polymerization reactions. Contradictory, in the absence of minerals, homogeneous vapor-phase cracking reactions were dominant over polymerization/charring reactions (400-550 C, 1-15 s). With increasing vapor residence time, the oil yield reached an asymptotic value, which decreased with temperature. At a vapor temperature of 400 C no decrease in oil yield was observed, but dedicated analysis showed that homogeneous vapor to vapor reactions had occurred. a Sigma-Aldrich, P9333, purity [ 99.0%, b Sigma-Aldrich S7795, purity [ 99.0%, c Sigma-Aldrich 23653-412 K 2 CO 3 , purity ¼ 99.0%

Pine wood was pyrolyzed in a 1 kg/h fluidized bed fast pyrolysis reactor that allows a residence time of pine wood particles up to 25 min. The reactor temperature was varied between 330 and 580 °C to study the effect on product yields and oil composition. Apart from the physical−chemical analysis, a pyrolysis oil quality assessment has been performed by using two applications. The pyrolysis oils were tested in a laboratory scale atomizer and in a hydrodeoxygenation unit for upgrading/stabilizing of the pyrolysis oil. The pyrolysis oil yield increases from 330 to 450 °C, is nearly constant between 450 and 530 °C, and decreases again at a pyrolysis temperature of 580 °C. At temperatures of 360 and 580 °C, total pyrolysis oil yields of, respectively, 58 and 56 dry wt % can still be obtained. The produced amount of water is already significant at a reactor temperature of 360 °C and becomes constant at a temperature of 400 °C. At a temperature of 580 °C, the water production starts to decrease slightly. Initially the number average molecular weight of the pyrolysis oil increases at increasing temperatures, which is ascribed to the observed increase in concentration of water insoluble compound in the pyrolysis oil. At a temperature of 580 °C, the number average molecular weight, viscosity, and the amount of produced water insoluble compounds decreases. The oil obtained at a pyrolysis temperature of 360 °C produced less char, 2 versus 5 wt %, compared to the oil obtained at a pyrolysis temperature of 530 °C in our atomizer/gasifier. About 100% of the carbon goes to the gas phase compared to 84% for the oil obtained at a pyrolysis temperature of 530 °C. Therefore, the 360 °C oil has a better quality for this unit under the applied conditions (850 °C and droplet sizes of 50± μm) Testing the three pyrolysis oils (pyrolysis temperatures of 330, 530, and 580 °C) in the hydrodeoxygenation unit showed that pyrolysis oil with a lower viscosity resulted in deoxygenated oil of lower viscosity. The oxygen content of the three oils was almost the same, but the yield of the deoxygenated oils obtained at a pyrolysis temperature of 330 °C was significantly lower. Together with chemical and physical analyzes of the pyrolysis oils, feeding the pyrolysis oil into a test units relevant for applications, direct information on the effect of varied pyrolysis process parameters on the quality and applicability of the pyrolysis oil is obtained.

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In this study, the acid-catalyzed conversion of xylose to furfural was investigated in 20 solvents ranging from water, alcohol, ketones, furans, ethers, esters, hydrocarbons, and aromatics with the aim to understand their involvement in each step from xylose to furfural. Compared with water, alcohols can stabilize the reactive intermediates, promote the formation of furfural, and slow its degradation with prolonged reaction times. Iso-propanol and 2-butanol can direct the conversion of xylose to levulinic esters via transfer hydrogenation catalyzed by a Brønsted acid catalyst. The other solvents with the carbonyl groups (i.e., ketones) or conjugated π bonds (e.g., furan) react with both xylose and furfural. Either xylose cannot make its way to furfural or furfural cannot survive for long in these solvents. In ethers, hydrocarbons, and aromatics, the formation of furfural is quick but so is the degradation of furfural due to the aprotic properties of these solvents. In an ester like methyl formate, xylose can be converted to furfural selectively and efficiently. Approximately 70% yields of furfural were achieved at 150 °C in a very short time, and more importantly, methyl formate is highly volatile (boiling point: 32 °C). It can be distilled from furfural very easily, making it a promising solvent for furfural production. The solvents also interact with the acidic resin catalysts in varied ways due to their different polarities and molecular size/shape, determining the availability of the acidic sites on the inner surfaces of the catalysts.

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