Online upgrading of organic vapors from the fast pyrolysis of biomass

第36卷第6期燃料化学学报Vol. 36 No.62008年12月Journal of Fuel Chemistry and TechnologyDee. 2008Article ID: 0252-2409<20066606Online upgrading of organic vapors from the fast pyrolysis of biomassLI Hong-yu, YAN Yongjie, REN Zheng-wei(Research Center for Biomass Energy，State Key Laboratory of Bioreactor Engineering, East China University ofScince and Technology, Shanghai 200237)developed to produce a high quality liquid product from the biomass. The insallation consisted of a fuidized bed reactor forpyrolysis and a packed bed reactor for upgrading. The proper pyrolysis processing conditions with a temperature of 500 Cand a flow rale of4 m' .h 1 were determined in advance. Under such condions , the efects of temperalure and weighthourly space velocity ( WHSV) on both the liquid yields and the oil qualities of the online catalytic cracking prucess wereinvestigated. 'The results showed that such a combined process had the superiority of increasing the liquid yield andimproving the product quality over the separate processes. Furthermore, when the lemperature was 500 C, witha WHSV o[3h"', the liquid yield reached the maximum and the oxygenic compounds also decreased obviously.Key words: fast pyrolysis; catalytie crucking; HZSM-5; upgrade; bio-oilCLC number: TK6Document code: ABiomass is a renewable energy source withmethod by converting oxygenated feedstock to lighterincreasing potential in the worldwide energy market.fractions that fall particularly in the gasoline boilingIs net carbon dioxide emission to atmosphere leads to arang”。There are two main catalytic crackinglower greenhouse effect'- . Furthermore, its nitrogenprocesses, off-line catalytic cracking, which uses bio-(N) and sulfur (S) contents are very low. The mostoil as raw material and online catalytic cracking, whichimportant advantage of biomass is that it can beuses the pyrolysis vapors as raw materal'l4” 20. Onconverted to liquid, solid, or gaseous fuels"，unlikeaccount of the thermal instability of bio-oil, the off-lineother renewable sources of energy ( i. e. ，wind,catalytic cracking process needs to vaporize bio-oilsolar), which only give heat and power.before catalytic cracking, which causes coke formationThe energy from biomass can be obtained byreactions，for example， thermal cracking andvarious technologies , such as combustion, gasification ,condensation reactions. Online catalytic cracking is notnd pyrolysis. Compared with combustion andonly available to avoid the vaporization process, butgasification of biomass，pyrolysis has the advantage ofalso helpful to reduce the energy cost and lengthen thea liquid product being produced ( the bio-oil) ，whichlife of the catalyst' 101.may be slored and transported economically. Bio-oil,In this article， biomass was pyrolyzed in aas one of the most important products from biomass,fluidized bed reactor and the online upgrading processcan be used as a fuel in boilers, diesel engines or gaswas performed to catalyze the vapor phase of the liquidturbines for the production of heat ，power or combinedin a fixed bed reactor with HZSM-5. For each reactionheat and power ( CHP). Moreover , bio-oil productionunit, the operation conditions were investigated so thatand heat and/ or power generation can be carried oupreferential temperature and weight hourly spaceindependently at diferent locations and times.velocity ( WHSV) were finally determined.However,bio-oil,， directly derived from various1 Experimentalprocesses-9, is usually of high viscosity and highcontent of oxygenic components, with low stability and1.1 Materials Sawdust as feedstock ( particle sizeheat value. Upgrading， which is necessary to improvelessthan3mm)wasdriedfor2hat105Cinthe.its quality by reducing the content of oxygenates ,oven, to remove extrinsic water before use.The reagents used as solvents in the productusually involves processes such as catalytic cracking,hydrogenation, and steam reforming[10-12].analysis , such as methanol and dichloromethane, wereAlthough the results of catalytic cracking are notof analytical grade.so encouraging now due to high coking and low qualityThe catalyst was prepared by blending HZSM-5of the fuels obtained, it is still regarded as an economiczeolite with Kaolin nowder, at a weight ratio of 1: 1.中国煤化工Received date: 2008 05-13; Received in revised form: 2008 08 _26.MYHCNMHGFoundation item: Major State Basic Research Development Prugram of China (973Corresponding author: YAN Yongje, Tel & Fax: 021 64253409, E-mail: yyansc@ online. sh. cn.Author introduction: LI Hongyu( 1981-), male, E mail; hongyu. li@ 126. com.本文的英文电f版巾Elsevier出版社在ScieneDiret上出版( htp:/www. sciencediret. rom/ science/joumal/18725813)。第6期LI Hong-yu et al. : Online upgrading of organic vapors from the fast pyrolysis of biomass667_The mixture was dried at 120 C for 10 h and then~3.0 mm in size.calcined at 500 C for 1 h after the heating process at aThe physical properties of the catalyst wererate of 3.0 C/min ~4.0 C/min. The finallyanalyzed and listed in Table 1.completed mixture was crushed into particles 2. 0 mmTable 1 Properties of catalystBET surface Average porePore volumeAcidAcid quantityCatalystSi/Alarea A/m°'g~'size d/nmon/cm’.g'intensity'2")/mmol.g 1HZSM-5381. 90. 56500. 1729.+0.8