Influence of Particle Size, Reactor Temperature and Gas Phase Reactions on Fast Pyrolysis of Beech Wood

In the present work, a drop tube reactor (DTR) and a horizontal tubular reactor (HTR) were used to study the pyrolysis behaviour of beech wood particles of different sizes under the conditions encountered in industrial fluidized bed gasifiers, namely high external heat flux (105 106 W.m-2) and high temperature (800 1000°C). The influence of the reactor temperature (800 and 950°C), of particle size (from 350 µm to 6 mm), and of gas residence time (from 1 to 10 s) were examined. Under the explored conditions, when pyrolysis is finished, more than 80 wt.% of virgin wood is converted into gas and less than 13 wt.% remains in solid. In the gas phase, CO is the main gaseous product (50 wt.% of virgin wood), followed by H2 (molar ratios of H2/CO are between 0.35 to 0.55), H2O, CO2 and CH4. Species C2H2, C2H4, C2H6 and C6H6 are present in much lower amounts. The increase of temperature increases the rate of solid devolatilization and favours the cracking reactions of hydrocarbons. The increase of particle size increases the required time for completing pyrolysis. Meanwhile, the results obtained at 950°C show that the final products distribution at the end of pyrolysis is almost the same for the particles between 350 and 800 µm. The increase of the particle size from 800 µm to 6 mm seems to have some influence on the final products distribution. The gas phase reactions mainly change the yields of light hydrocarbons and H2: the increase of gas residence time favours the cracking reactions of hydrocarbons and thus leads to a higher H2 yield.

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Molecular mechanisms for the gas-phase conversion of intermediates during cellulose gasification under nitrogen and oxygen/nitrogen

Chemical Industry and Chemical Engineering Quarterly ◽

10.2298/ciceq160325018f ◽

2016 ◽

Vol 22 (4) ◽

pp. 343-353 ◽

Cited By ~ 6

Author(s):

Asuka Fukutome ◽

Haruo Kawamoto ◽

Shiro Saka

Keyword(s):

Gas Phase ◽

Residence Time ◽

Molecular Mechanisms ◽

High Efficiency ◽

Experimental Setup ◽

Phase Conversion ◽

Gas Phase Reactions ◽

Secondary Reaction Zone ◽

Hydrocarbon Gas ◽

Molten Phase

Gas-phase conversions of volatile intermediates from cellulose (AvicelPH-101) were studied using a two-stage experimental setup and compared with those of levoglucosan (1,6-anhydro-b-D-glucopyranose). Under N2or 7% O2/N2flow, vapors produced from the pyrolysis zone (500?C) degraded in the secondary reaction zone at 400,500, 600 or 900?C (residence time:0.8-1.4 s). The 69.3% (C-based) of levoglucosan was obtained at 400?C under N2flow along with 1,6-anhydro-b-D-glucofuranose (8.3 %, C-based), indicating that these anhydrosugars are the major volatile intermediates from cellulose pyrolysis. Levoglucosan and other volatiles started to fragment at 600?C, and cellulose was completely gasified at 900?C. Most gas/tar formations are explained by gas-phase reactions of levoglucosan reported previously, except for some minor reactions originating from the molten-phase pyrolysis, which produced benzene, furans and 1,6-anhydro-b-D-glucofuranose. Synergetic effects of O2and volatiles accelerated fragmentation and cellulose gasification was completed at 600?C, which reduced benzene and hydrocarbon gas productions. The molecular mechanisms including the action of O2as a biradical are discussed. These lines of information provide insights into the development of tar-free clean gasification that maintains high efficiency.

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Continuous Catalyst-Free Esterification of Oleic Acid in Compressed Ethanol

International Journal of Chemical Engineering ◽

10.1155/2014/803783 ◽

2014 ◽

Vol 2014 ◽

pp. 1-5 ◽

Cited By ~ 8

Author(s):

Ana Carolina de Araujo Abdala ◽

Vitor Augusto dos Santos Garcia ◽

Caroline Portilho Trentini ◽

Lúcio Cardozo Filho ◽

Edson Antonio da Silva ◽

...

Keyword(s):

Oleic Acid ◽

Residence Time ◽

Tubular Reactor ◽

Reaction Medium ◽

Ethyl Esters ◽

Molar Ratio ◽

Molar Ratios ◽

Catalyst Free ◽

Free Process ◽

Positive Effect

The esterification of oleic acid in a continuous catalyst-free process using compressed ethanol was investigated in the present study. Experiments were performed in a tubular reactor and variables investigated were temperature, pressure, and oleic acid to ethanol molar ratio for different residence time. Results demonstrated that temperature, in the range of 473 K to 573 K, and pressure had a positive effect on fatty acid ethyl esters (FAEE) production. In the experimental range investigated, high conversions can be obtained at low ethanol concentrations in the reaction medium and it was observed that oleic acid to ethanol molar ratios greater than 1 : 6 show no significant increase in conversion. Nonnegligible reaction conversions (>90%) were achieved at 573 K, 20 MPa, oleic acid to ethanol molar ratio of 1 : 6, and 20 minutes of residence time.

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Carbon Dioxide Hydrogenation by Means of Plasmonic Resonance Activation in Silica Aerogel Media

Materials ◽

10.3390/ma11112134 ◽

2018 ◽

Vol 11 (11) ◽

pp. 2134 ◽

Cited By ~ 1

Author(s):

Sergio Muñoz ◽

Alexander Navarrete ◽

Ángel Martín ◽

Roland Dittmeyer ◽

M. Cocero

Keyword(s):

Carbon Dioxide ◽

Gas Phase ◽

High Pressures ◽

Copper Catalysts ◽

Hydrogenation Reaction ◽

Gas Phase Reactions ◽

Conversion Rates ◽

High Temperature Processes ◽

Carbon Dioxide Hydrogenation ◽

Reactor Temperature

Surface Plasmon Resonance can be used to activate zinc oxide/copper catalysts in order to perform the carbon dioxide hydrogenation reaction by means of light energy, avoiding high-temperature processes. The synthesis and impregnation methods have been designed to fill glass microreactors with ZnO/Cu nanoparticles supported on transparent silica aerogels to maximize the light absorbed by the catalyst. A LED device surrounding the glass microreactors provided white light to activate the catalyst homogeneously throughout the reactor. Temperature, pressure, amount of catalyst and gases flow were studied as possible variables to enhance the process trying to maximize CO2 conversion rates, achieving the best results working at high pressures. The use of transparent SiO2 Aerogels as supports for photocatalytic gas phase reactions even under high-pressure conditions is demonstrated.

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Pyrolysis of brown algae (Bifurcaria Bifurcata) in a stainless steel tubular reactor: From a review to a case study

Progress in Agricultural Engineering Sciences ◽

10.1556/446.14.2018.1.2 ◽

2018 ◽

Vol 14 (1) ◽

pp. 31-60 ◽

Cited By ~ 1

Author(s):

M. Y. Guida ◽

F. E. Laghchioua ◽

A. Hannioui

Keyword(s):

Particle Size ◽

Stainless Steel ◽

Flow Rate ◽

Brown Algae ◽

Tubular Reactor ◽

Nitrogen Flow ◽

Nitrogen Flow Rate ◽

Bifurcaria Bifurcata ◽

Bio Oil

This article deals with fast pyrolysis of brown algae, such as Bifurcaria Bifurcata at the range of temperature 300–800 °C in a stainless steel tubular reactor. After a literature review on algae and its importance in renewable sector, a case study was done on pyrolysis of brown algae especially, Bifurcaria Bifurcata. The aim was to experimentally investigate how the temperature, the particle size, the nitrogen flow rate (N2) and the heating rate affect bio-oil, bio-char and gaseous products. These parameters were varied in the ranges of 5–50 °C/min, below 0.2–1 mm and 20–200 mL. min–1, respectively. The maximum bio-oil yield of 41.3wt% was obtained at a pyrolysis temperature of 600 °C, particle size between 0.2–0.5 mm, nitrogen flow rate (N2) of 100 mL. min–1 and heating rate of 5 °C/min. Liquid product obtained under the most suitable and optimal condition was characterized by elemental analysis, 1H-NMR, FT-IR and GC-MS. The analysis of bio-oil showed that bio-oil from Bifurcaria Bifurcata could be a potential source of renewable fuel production and value added chemicals.

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Gas-Phase Reactions

10.1007/978-3-642-67608-6 ◽

1981 ◽

Cited By ~ 41

Author(s):

Victor N. Kondratiev ◽

Evgeniĭ E. Nikitin

Keyword(s):

Gas Phase ◽

Gas Phase Reactions

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Reduction Mechanism of Fine Hematite Ore Particles in Suspension

Metallurgical and Materials Transactions B ◽

10.1007/s11663-021-02173-y ◽

2021 ◽

Author(s):

Zhiyuan Chen ◽

Christiaan Zeilstra ◽

Jan van der Stel ◽

Jilt Sietsma ◽

Yongxiang Yang

Keyword(s):

Particle Size ◽

Temperature Drop ◽

Reduction Rate ◽

Reduction Process ◽

Reciprocal Relationship ◽

Drop Tube ◽

Surface Nucleation ◽

Order Of Magnitude ◽

Relationship Of ◽

Kinetics Of

AbstractIn order to understand the pre-reduction behaviour of fine hematite particles in the HIsarna process, change of morphology, phase and crystallography during the reduction were investigated in the high temperature drop tube furnace. Polycrystalline magnetite shell formed within 200 ms during the reduction. The grain size of the magnetite is in the order of magnitude of 10 µm. Lath magnetite was observed in the partly reduced samples. The grain boundary of magnetite was reduced to molten FeO firstly, and then the particle turned to be a droplet. The Johnson-Mehl-Avrami-Kolmogorov model is proposed to describe the kinetics of the reduction process. Both bulk and surface nucleation occurred during the reduction, which leads to the effect of size on the reduction rate in the nucleation and growth process. As a result, the reduction rate constant of hematite particles increases with the increasing particle size until 85 µm. It then decreases with a reciprocal relationship of the particle size above 85 µm.

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Continuous citrate‐capped gold nanoparticle synthesis in a two‐phase flow reactor

Journal of Flow Chemistry ◽

10.1007/s41981-021-00172-3 ◽

2021 ◽

Author(s):

Spyridon Damilos ◽

Ioannis Alissandratos ◽

Luca Panariello ◽

Anand N. P. Radhakrishnan ◽

Enhong Cao ◽

...

Keyword(s):

Particle Size ◽

Gold Nanoparticles ◽

Residence Time ◽

Flow Reactor ◽

Phase Flow ◽

Continuous Manufacturing ◽

Two Phase ◽

Process Yield ◽

Au Nps ◽

Manufacturing Platform

AbstractA continuous manufacturing platform was developed for the synthesis of aqueous colloidal 10–20 nm gold nanoparticles (Au NPs) in a flow reactor using chloroauric acid, sodium citrate and citric acid at 95 oC and 2.3 bar(a) pressure. The use of a two-phase flow system – using heptane as the continuous phase – prevented fouling on the reactor walls, while improving the residence time distribution. Continuous syntheses for up to 2 h demonstrated its potential application for continuous manufacturing, while live quality control was established using online UV-Vis photospectrometry that monitored the particle size and process yield. The synthesis was stable and reproducible over time for gold precursor concentration above 0.23 mM (after mixing), resulting in average particle size between 12 and 15 nm. A hydrophobic membrane separator provided successful separation of the aqueous and organic phases and collection of colloidal Au NPs in flow. Process yield increased at higher inlet flow rates (from 70 % to almost 100 %), due to lower residence time of the colloidal solution in the separator resulting in less fouling in the PTFE membrane. This study addresses the challenges for the translation of the synthesis from batch to flow and provides tools for the development of a continuous manufacturing platform for gold nanoparticles.Graphical abstract

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