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ABSTRACT: Pyrolysis of peanut shell in a fluidized bed to produce bio-oil is investigated as a useful way to utilize the agriculture residues in China. The influence of reaction temperature and the flow rate of carrier gas (N2) on the pyrolysis product distribution and some characteristics of these products generated in the bench-scale fluidized-bed system developed in this study are quantified. The main components of bio-oil are classified into six categories including aldehydes, ketones, acids, esters, phenols, and alcohols that were analyzed with GC-MS. Properties of products (bio-oil, char, noncondensible gas) such as elemental analysis, moisture, heat value, kinematic viscosity, flashing point, and density, were also characterized. It was found out that the maximum yield of bio-oil, around 60% by weight, was achieved at reaction temperature at 500°C and the flow rate of N2 at 3.2 Nm3 h−1. N2 balance and total mass balance on this system were performed to demonstrate the result credibility of the experiments. Some other useful parameters based on the system were also obtained for future economic and design studies. © 2011 American Institute of Chemical Engineers Environ Prog, 2011
Environmental Progress & Sustainable Energy 02/2011; 30(1):11 - 18. · 1.65 Impact Factor
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ABSTRACT: Thermochemical production of hydrogen is anticipated to be one of the most cost-effective means of producing hydrogen fuel. Switchgrass, a warm-season, perennial grass that is native to many areas of the United States, is an attractive feedstock for this purpose. The goal of this study is to convert switchgrass into hydrogen by the sequential processes of thermal gasification in a fluidized bed reactor, catalytic steam reforming of tars, and the use of water-gas shift catalysts to enhance the concentration of hydrogen. Air-blown gasification of switchgrass produced relatively low concentrations of hydrogen (about 8.5 vol-%). Steam reforming of tars and light hydrocarbons and reacting steam with carbon monoxide via the water-gas shift reaction increased the hydrogen content in the producer gas to 27.1 vol-%. The catalysts used in the steam reformer and water-gas shift reactors were examined at the end of the trials using X-ray photoelectron spectroscopy and BET analysis. These analyses showed changes in pore size and pore size distribution. Although not evident during the tests, eventual degradation of the catalysts can be expected as the result of deposition of coke, sulfur, and chlorine on the catalysts.
11/2003;
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ABSTRACT: The goal of this research is to produce high concentrations of hydrogen from gasification of biomass. Air-blown gasification of biomass in fluidized bed reactors produces relatively low concentrations of hydrogen (about 8 vol.%). Steam reforming of tars and light hydrocarbons and reacting steam with carbon monoxide via the water–gas shift reaction can increase hydrogen content in the producer gas to almost 30 vol.%. In these experiments, the temperature, space velocity, and steam/gas ratio were varied to determine the effect of these variables on hydrogen production. Characterization of the catalysts by X-ray photoelectron spectroscopy (XPS) and BET analysis was also performed. These analyses showed that coke and small quantities of sulfur and chlorine deposited on the catalysts, although catalytic deactivation was not evident during the tests.
Fuel Processing Technology.
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ABSTRACT: The purpose of this study is to investigate catalytic destruction of tar formed during gasification of biomass, with the goal of improving the quality of the producer gas. This work focuses on nickel based catalysts treated with alkali in an effort to promote steam gasification of the coke that deposits on catalyst surfaces. A tar conversion system consisting of a guard bed and catalytic reactor was designed to treat the producer gas from an air blown, fluidized bed biomass gasifier. The guard bed used dolomite to crack the heavy tars. The catalytic reactor was used to evaluate three commercial steam reforming catalysts. These were the ICI46-1 catalyst from Imperial Chemical Industry and Z409 and RZ409 catalysts from Qilu Petrochemical Corp. in China. A 0.5–3 l/min slipstream from a 5 tpd biomass gasifier was used to test the tar conversion system. Gas and tar were sampled before and after the tar conversion system to evaluate the effectiveness of the system. Changes in gas composition as functions of catalytic bed temperature, space velocity and steam/TOC (total organic carbon) ratio are presented. Structural changes in the catalysts during the tests are also described.
Energy Conversion and Management.
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ABSTRACT: Biomass gasification is gaining attention as a route for biomass energy production. Producer gas from this process usually contains unacceptable levels of tar. Tar can cause operational problems in downstream processes by blocking gas coolers, filter elements and engine suction channels. Most producer gas applications require removal of at least part of the dust and tar before the gas can be used.In this study, olivine was used as a substrate for various catalyst formulations designed to steam reform tar to gas. Three catalysts were prepared by wet impregnation, yielding the following compositions: 3.0% NiO/olivine, 3.0% NiO/olivine doped with 1.0% CeO2 and 6.0% NiO/olivine. Benzene and toluene were selected as model compounds of biomass tar. Catalytic steam reforming of these compounds was performed in a bench scale fixed bed reactor at temperatures between 700 and 830 °C using a molar ratio of steam/carbon (S/C) equal to 5. The effect of catalyst composition on tar conversion and yields of various product gases were determined. Coking tendencies of the catalysts were determined, and characterization by XRD and SEM was performed. 3.0% NiO/olivine doped with 1.0% CeO2 was the most promising catalyst based on catalytic activity and its resistance to coking.
Energy Conversion and Management.
