A kinetic approach to catalytic pyrolysis of tars

Faúndez, J.; Garcı́a, Ximena; Gordon, Alfredo L.

doi:10.1016/s0378-3820(00)00141-7

Cited by 13 publications

(4 citation statements)

References 20 publications

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“…Kinetic Model of Tar Cracking in the Freeboard of Fluidized Bed. Faúndez et al think that the tar may be regarded to be composed of two fractions: one is a heavy fraction, containing the high molecular weight components, the other is a light fraction, being constituted by the low molecular weight components of the tar . Serio et al also suggest a lumped kinetic model.…”

Section: Resultsmentioning

confidence: 92%

Effects of Calcium Oxide on the Cracking of Coal Tar in the Freeboard of a Fluidized Bed

2004

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The effects of calcium oxide on tar cracking in the freeboard of a fluidized bed under different freeboard conditions have been investigated in order to reduce or eliminate the tar produced in coal pyrolysis and simultaneously to make coal gas of high qualities. Because no bubbles are in the freeboard, the tar would be contacted well with calcium oxide, and the tar cracking is improved. The results show that tar conversion increases apparently with the addition of calcium oxide, but the effect of calcium oxide on the tar conversion decreases gradually with freeboard temperature and is small above 700 °C, especially when the percentage of calcium oxide is increased from 6% to 12%. At lower freeboard temperature of 650 °C, the effect of calcium oxide on the tar conversion increases with residence time, apparently; however, at 750 °C the effect of calcium oxide on the tar conversion is only apparent at short residence time. The rate of tar cracking can be expressed by a simple first-order reaction, and the activation energy is decreased by 30% or 45% when 6% or 12% of calcium oxide is added, which is almost equal to the result of Lv and Yue [Lv, J. F.; Yue, G. X. J. Tsinghua Univ. ( Sci. Technol. ) 1997, 37 (2), 6−10.] in a fixed bed for benzene or toluene, respectively.

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Section: Resultsmentioning

confidence: 92%

Effects of Calcium Oxide on the Cracking of Coal Tar in the Freeboard of a Fluidized Bed

2004

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“…The kinetic model was proposed on the basis of the decomposition of tar with the following reaction, which was slightly modified from another reference: The heavy tar (HT) decomposes into gaseous product (GS), solid carbon (SC), and light tar (LT) over porous ore. In the case of high catalyst activity, the light tar also possibly decomposes into gases and solid carbon.…”

Section: Proposed Kinetic Modelmentioning

confidence: 99%

Tar Decomposition over a Porous Iron Ore Catalyst: Experiment and Kinetic Analysis

et al. 2018

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In the pyrolysis process, tar material may cause operational problems, such as pipe plugging, condensation, and tar aerosol formation. An unusual approach should be introduced to solve carbon deposition over a catalyst, which was a serious problem in the tar decomposition process. The kinetic analysis was evaluated in detail by the proposed system, tar decomposition over a porous catalyst of iron ore. Decomposition of lignite tar exhibited similar profiles of H2 and CO generation, which was rising shortly at the beginning of the reaction because the ore catalyst still owned high activity and there was no carbon poisoning. However, the excessive carbon deposition also occurred simultaneously. Both the kinetic constant and deactivation factor were evaluated successfully using a simple proposed model with ranges of 0.1275–0.5523 and 1.7206–2.5310 s–1, respectively, at 500–700 °C. The activation energy was also calculated on the basis of the Arrhenius equation, which was 44.86 kJ/mol. The deactivation factor exhibited a similar tendency with the amount of carbon deposition within pores of iron ore. It means that the carbon deposition within pores of ore was highly affected by catalyt activity. However, the high carbon content within an inactive ore catalyst offered an extra benefit in the steel production as raw material. Therefore, the tar decomposition over a porous iron ore was a promising catalyst, which was a cheap and abundant natural resource. In addition, this proposed system also offered a solution for problems related to the raw material, energy, and environment in the ironmaking industry.

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“…Considering the complexity of tar catalytic cracking, researchers worldwide selected the general first-order reaction kinetics model to describe the process of tar cracking. 22 In this model, all tar cracking reactions are regarded as simultaneously occurring and independent of one another.…”

Section: Performance Of Regenerated Catalyst Onmentioning

confidence: 99%

Catalytic Purification of Raw Gas from Biomass Gasification on Mo–Ni–Co/Cordierite Monolithic Catalyst

Lü

Xiong

et al. 2013

Energy Fuels

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This study presents the preparation of a 1Mo3Ni1Co/Cor catalyst by vacuum impregnation to obtain a clean biomass gasification product gas. The effects of the air equivalence ratio (ER) and catalytic temperature on tar cracking and gas reforming were investigated. The regeneration activity of the 1Mo3Ni1Co/Cor catalyst was also evaluated in biomass gasification. Results show that the choice of ER is highly important, and an increase in catalytic temperature is favorable for cleaning biomass gasification raw gas. When the ER and catalytic temperatures were 0.21 and 800 °C, the gas yield, tar conversion, and hydrogen yield reached 1.28 N m3/kg, 99.2%, and 49.3 g/kg, respectively. The regeneration activity of this catalyst is relatively stable and close to that of the fresh catalyst after a 4 h reaction; however, this activity is relatively lower than that of the fresh catalyst in the initial stage. This difference is caused by the formation of Mo2C in gas reforming. Finally, the activation energy and the pre-exponential factor of the catalyst calculated by first-order reaction kinetics model are 33.79 kJ/mol and 523 s–1, respectively.

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A kinetic approach to catalytic pyrolysis of tars

Cited by 13 publications

References 20 publications

Effects of Calcium Oxide on the Cracking of Coal Tar in the Freeboard of a Fluidized Bed

Effects of Calcium Oxide on the Cracking of Coal Tar in the Freeboard of a Fluidized Bed

Tar Decomposition over a Porous Iron Ore Catalyst: Experiment and Kinetic Analysis

Catalytic Purification of Raw Gas from Biomass Gasification on Mo–Ni–Co/Cordierite Monolithic Catalyst

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