Energy Fuels 2010, 24, 6616–6623 Published on Web 11/11/2010
: DOI:10.1021/ef1011963
Effect of Selective Condensation on the Characterization of Bio-oil from Pine Sawdust Fast Pyrolysis Using a Fluidized-Bed Reactor Tianju Chen, Chunjian Deng, and Ronghou Liu* Biomass Energy Engineering Research Centre, School of Agriculture and Biology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, People’s Republic of China Received September 4, 2010. Revised Manuscript Received October 25, 2010
To maximize selective condensation of organics that are of known higher commercial value and to investigate the effects of selective condensation on bio-oil characterization, pine sawdust was pyrolyzed in a 1-5 kg/h bench-scale fluidized-bed reactor. In the experiments, the selective condensers and electrostatic precipitator were used to condense the pyrolysis vapors. In addition, the characterization of bio-oils, gases, and biochar was investigated. The results showed that the total bio-oil, gases, and char yields were 41.5, 43.3, and 15.2%, respectively, and 86.2 wt % water steam was condensed in condenser 1. The bio-oil condensed in the later condensers has a lower water content, higher pH value, higher heating value, and higher kinetic viscosity compared to the first one. Analysis of the 1, 4, and 5 bio-oils with gas chromatography-mass spectrometry (GC-MS) showed that 102 types of chemical compounds were detected and most of the compounds were condensed at different condensers. Therefore, the selective condensation is useful to separate the water and chemical compounds from bio-oil compared to direct contacting condensing. The gas products were mainly CO, H2, CO2, CH4, and C2-C4. Char characteristics were determined by ultimate analysis, Fourier transform infrared (FTIR) spectrometry, and scanning electron microscopy (SEM) methods. A lot of bonds, such as -NH-, -CH-, -CdC-, -CH3, and -C-O-C-, were found in the char samples. It was observed that the surface morphology of the pine particle changed after pyrolysis, and it became thinner and shrank. The thermal decomposition of chemical bonds and the melting of some compounds can break the chemical bonds of the original material, and the chemical bonds with lower bond energies break with priority. The research has provided a useful reference for biomass fast pyrolysis.
There is extensive literature on the pyrolysis of biomass.4-10 The main objective of these studies was to obtain alternative liquid fuels by decomposing biomass samples at different pyrolysis conditions, and the obtained bio-oil was also investigated by various instrumental techniques. Bio-oil is clean, cost-effective, CO2-neutral, and easy to transport and has low sulfur content, making biomass a dominant choice for the replacement of fossil fuels.11 Its use as a fuel in boilers and engines has been tested.12-14 Properties and chemical composition of bio-oil are distinct from petroleum fuel, and in general terms, with its relatively high content of water and
1. Introduction Biomass is organic material formed through photosynthesis, including all kinds of animals, plants, and microorganisms, and the so-called “biomass energy” refers to a certain energy form stored as a form of chemical energy in biomass from solar energy. It is one of the largest energy source reserves in the world. Conversion of biomass to energy is undertaken using two main process technologies: thermochemical and biological. Within thermochemical conversion technology, four process options are available: direct combustion, pyrolysis, gasification, and liquefaction.1 Selection of these conversion technologies for biomass depends upon the form in which energy is required. Fast pyrolysis is a high-temperature process, in which the feedstock is rapidly heated in the absence of air, vaporises, and condenses to a dark brown mobile liquid, which has a heating value of about half that of conventional fuel oil. Fast pyrolysis always produces a gas, a vapor that can be collected as a liquid, which is called bio-oil, and a solid char. If the process is carefully controlled, high yields of liquid can be achieved.2,3
(4) Liu, R.-H.; Deng, C.-J.; Wang, J. Fast pyrolysis of corn straw for bio-oil production in a bench-scale fluidized bed reactor. Energy Sources, Part A 2010, 32, 10–19. (5) Bridgwater, A. V. Principles and practice of biomass fast pyrolysis processes for liquids. J. Anal. Appl. Pyrolysis 1999, 51, 3–22. (6) Putun, E.; Ates, F.; Putun, A. Catalytic pyrolysis of biomass in inert and steam atmospheres. Fuel 2008, 87, 815–824. (7) Mullen, C. A.; Boateng, A. A. Chemical composition of bio-oils produced by fast pyrolysis of two energy crops. Energy Fuels 2008, 22, 2104–2109. (8) Lievens, C.; Carleer, R.; Cornelissen, T.; Yperman, J. Fast pyrolysis of heavy metal contaminated willow: Influence of the plant part. Fuel 2009, 88, 1417–1425. (9) Smith, J.; Garcia-Perez, M.; Das, K. C. Producing fuel and specialty chemicals from the slow pyrolysis of poultry DAF skimmings. J. Anal. Appl. Pyrolysis 2009, 86, 115–121. (10) Oasmaa, A.; Sipila, K.; Solantausta, Y.; Kuoppala, E. Quality improvement of pyrolysis liquid: Effect of light volatiles on the stability of pyrolysis liquids. Energy Fuels 2005, 19, 2556–2561. (11) Nader, M.; Pulikesi, M.; Thilakavathi, M.; Renata, R. Analysis of bio-oil, biogas, and biochar from pressurized pyrolysis of wheat straw using a tubular reactor. Energy Fuels 2009, 23, 2736–2742.
*To whom correspondence should be addressed. Telephone: 0086-2134205744. Fax: 0086-21-34205877. E-mail:
[email protected]. (1) Peter, M. Energy production from biomass (part 2): Conversion technologies. Bioresour. Technol. 2002, 83, 47–54. (2) Bridgwater, A. V.; Peacocke, G. V. C. Fast pyrolysis processes for biomass. Renewable Sustainable Energy Rev. 2000, 4, 1–73. (3) Liu, R.; Wang, H.; Li, T.; Zhang, C.; Wu, L. Production and characterisation of bio-oil from biomass fast pyrolysis in a fluidised bed reactor. Int. J. Global Energy Issues 2007, 28 (4), 347–356. r 2010 American Chemical Society
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Energy Fuels 2010, 24, 6616–6623
: DOI:10.1021/ef1011963
Chen et al.
Table 1. Proximate and Ultimate Analyses of Pine Sawdust proximate analysis moisture (wt %) volatiles (wt %) ash (wt %) fixed carbon (wt %) a
8-10 77.28 0.85 14.28
elemental analysis carbon (wt %) hydrogen (wt %) nitrogen (wt %) oxygena (wt %)
48.42 5.51
