Gas-phase vs. material-kinetic limits on the redox response of nonstoichiometric oxides

2017 ◽  
Vol 19 (10) ◽  
pp. 7420-7430 ◽  
Author(s):  
Ho-Il Ji ◽  
Timothy C. Davenport ◽  
Michael J. Ignatowich ◽  
Sossina M. Haile
Keyword(s):  
Specific Surface ◽  
Gas Phase ◽  
Surface Area ◽  
Specific Surface Area ◽  
Flow Rate ◽  
Gas Flow ◽  
Gas Composition ◽  
Gas Flow Rate ◽  
Nonstoichiometric Oxides ◽  
Rate Of Response

The rate of response of CeO2−δ to changes in gas composition can be systematically manipulated via changes to gas flow rate or material specific surface area.

Direct molecular hydrogen sulphide scrubbing with hollow fibre membranes

2001 ◽  
Vol 44 (9) ◽  
pp. 135-142 ◽  
Author(s):  
N. Boucil ◽  
B. Jefferson ◽  
S.A. Parsons ◽  
S.J. Judd ◽  
R.M. Stuetz
Keyword(s):  
Mass Transfer ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Flow Rate ◽  
Hydrogen Sulphide ◽  
Gas Flow ◽  
Hollow Fibre ◽  
The Other ◽  
Gas Flow Rate

The emission of hydrogen sulphide is a major problem associated with anaerobic treatment of sulphate and sulphite containing wastewaters. Conventional absorbing processes, such as packed towers, spray towers or bubble columns, are all constrained by factors such as flooding and foaming. Membrane systems, on the other hand, enable independent control of the liquid and gas flow rate and a step change order of magnitude increase in the specific surface area of the contact process. The membrane acts as a gas absorber with a design similar to a shell and tube heat exchanger. On the other hand, they are limited by facets of the membrane such as its resistance to mass transfer and permselectivity, as well as its cost. The work presented in this paper refers to an absorption process based on a non-wetted hollow fibre membrane for the scrubbing of hydrogen sulphide from air, with water as the contact solvent. Results presented describe the performance of the unit in terms of overall transfer and outlet liquid concentration as a function of circulation regime, gas flow rate, liquid flow rate and specific surface area. In particular, results are presented using traditional plots of Sherwood number (Sh) against Graetz (Gr) number for the liquid flowing in the lumens, such that experimental and available empirical descriptions of the process performance are directly compared. Results suggest that, as expected, very efficient mass transfer is obtained. However, the mass transfer was found to reach a maximum value against Gr, contrary to available empirical models.

scholarly journals Effects of CO2 Bubble Size, CO2 Flow Rate and Calcium Source on the Size and Specific Surface Area of CaCO3 Particles

Energies ◽  
2015 ◽  
Vol 8 (10) ◽  
pp. 12304-12313 ◽  
Author(s):  
Jun-Hwan Bang ◽  
Kyungsun Song ◽  
Sangwon Park ◽  
Chi Jeon ◽  
Seung-Woo Lee ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Flow Rate ◽  
Bubble Size ◽  
Calcium Source ◽  
Co2 Flow

Activated carbon load equalization of transient concentrations of gas-phase toluene: Effect of gas flow rate during pollutant non-loading intervals

2010 ◽  
Vol 157 (2-3) ◽  
pp. 339-347 ◽  
Author(s):  
Marilou M. Nabatilan ◽  
Ameziane Harhad ◽  
Peter R. Wolenski ◽  
William M. Moe
Keyword(s):  
Activated Carbon ◽  
Gas Phase ◽  
Flow Rate ◽  
Gas Flow ◽  
Gas Flow Rate ◽  
Carbon Load

KARAKTERISTIK FISIK NANOKOMPOSIT ZNO/Fe2O3 YANG DIBUAT MENGGUNAKAN FLAME SPRAY PYROLISIS DENGAN VARIASI LAJU ALIR GAS PEMBAWA

EKUILIBIUM ◽  
2011 ◽  
Vol 10 (1) ◽  
Author(s):  
Arif Jumari ◽  
Agus Purwanto ◽  
Sperisa Distantina
Keyword(s):  
Particle Size ◽  
Surface Area ◽  
Flow Rate ◽  
Gas Flow ◽  
Catalytic Performance ◽  
Flame Spray Pyrolysis ◽  
Flame Spray ◽  
Gas Flow Rate ◽  
Carrier Gas ◽  
Carrier Gas Flow

<p><strong><em>Abstract: </em></strong><em>Biodiesel is a very potential alternative energy resources. Producing of Biodiesel was much carried out using homogeneous catalytic esterification of vegetable oil and alcohol. These proces had many disanvantages. ZnO as a transesterification catalyst has given high yield. To improve the catalytic performance, the surface area per mas of catalyst must be increased by decreasing the size of particle. To ease the separation between product and catalyst, the magnetic  behaviour should be added to the catalyst. The aim of the research were to obtain nanocomposite ZnO/Fe<sub>2</sub>O<sub>3</sub> and determine physical characteristic as well as catalytic and separation performance. Nanocomposite ZnO/Fe<sub>2</sub>O<sub>3</sub> was synthesized by flame spray pyrolysis method. Assisted by carrier air precursor solution of Zn(NO<sub>3</sub>)<sub>2</sub> and Fe(NO<sub>3</sub>)<sub>3</sub> was nebulized and flowed to the inner tube of the burner. Nebulasation was carried out by varying carrier gas flow rate but  at constant rateof nebulization. LPG gas dan oxidant air  were flowed to the inner annulus  and outer annulus, respectively. The solid produced was separated from gas by particle filter. The solid particle was then examined by XRD , FE-SEM and BET as wel as catalytic performance. The result showed that the crystalinity of samples decreased by increasing the carrier gas flow rate. The particle size was not influenced by carrier gas flow rate and the size were dominantly between 50-100 nm. A part of particle was flowerlike particle.  The specific surface area  of particle was not inflenced by carrier gas flow rate and its value was 50.5 m<sup>2</sup>/gram.</em></p><p><em> </em><strong><em>Keywords</em></strong><em> : Tran-esterification,  nanocomposite ZnO/Fe<sub>2</sub>O<sub>3</sub>,  flame spray pyrolysis,   carrier gas, particle size,  particle morphology, specific surface area </em></p>

Effect of concentration and gas flow rate on the removal of gas-phase trichloroethylene in a novel packed biofilter

2020 ◽  
Vol 9 ◽  
pp. 100387
Author(s):  
Divya Baskaran ◽  
Ravi Rajamanickam ◽  
Baskaran Vaidyalingam
Keyword(s):  
Gas Phase ◽  
Flow Rate ◽  
Gas Flow ◽  
Gas Flow Rate

scholarly journals Purification of the gas after pyrolysis in coupled plasma-catalytic system

2017 ◽  
Vol 19 (4) ◽  
pp. 94-98 ◽  
Author(s):  
Michał Młotek ◽  
Bogdan Ulejczyk ◽  
Joanna Woroszył ◽  
Irmina Walerczak ◽  
Krzysztof Krawczyk
Keyword(s):  
Catalytic System ◽  
Flow Rate ◽  
Gas Flow ◽  
Homogeneous System ◽  
Discharge Power ◽  
Gas Composition ◽  
Gas Flow Rate ◽  
Gliding Discharge ◽  
The One ◽  
Pyrolysis Of Biomass

Abstract Gliding discharge and coupled plasma-catalytic system were used for toluene conversion in a gas composition such as the one obtained during pyrolysis of biomass. The chosen catalyst was G-0117, which is an industrial catalyst for methane conversion manufactured by INS Pulawy (Poland). The effects of discharge power, initial concentration of toluene, gas flow rate and the presence of the bed of the G-0117 catalyst on the conversion of C7H8, a model tars compounds were investigated. Conversion of coluene increases with discharge power and the highest one was noted in the coupled plasma-catalytic system. It was higher than that in the homogeneous system of gliding discharge. When applying a reactor with reduced G-0117 and CO (0.15 mol%), CO2 (0.15 mol%), H2 (0.30 mol%), N2 (0.40 mol%), 4000 ppm of toluene and gas flow rate of 1.5 Nm3/h, the conversion of toluene was higher than 99%. In the coupled plasma-catalytic system with G-0117 methanation of carbon oxides was observed.

Effects of concentration and gas flow rate on the removal of gas-phase toluene and xylene mixture in a compost biofilter

2018 ◽  
Vol 248 ◽  
pp. 28-35 ◽  
Author(s):  
Eldon R. Rene ◽  
Natalia Sergienko ◽  
Torsha Goswami ◽  
M. Estefanía López ◽  
Gopalakrishnan Kumar ◽  
...  
Keyword(s):  
Gas Phase ◽  
Flow Rate ◽  
Gas Flow ◽  
Gas Flow Rate

scholarly journals Kinetic Aspects of Phosphorus Removal from Electromagnetically Levitated 600 MPa Steel Droplets

Metals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1460
Author(s):  
Qi Jiang ◽  
Guifang Zhang ◽  
Yindong Yang ◽  
Alexander McLean ◽  
Lei Gao
Keyword(s):  
Gas Phase ◽  
Flow Rate ◽  
Phosphorus Removal ◽  
Gas Flow ◽  
Electromagnetic Levitation ◽  
Effect Of Temperature ◽  
Gas Flow Rate ◽  
Electromagnetically Levitated ◽  
Rate Controlling Step ◽  
Good Agreement

A kinetic model was developed to study the dephosphorization of 600 MPa steel droplets under electromagnetic levitation conditions. The relationships which were derived from the model between dephosphorization and the influence of temperature and gas flow rate were in good agreement with experimental data. Both temperature and gas flow rate were conducive to the evaporation of phosphorus, with the effect of temperature having a greater influence than that of the gas velocity. The results show that the rate-controlling step for the dephosphorization process was diffusion within the gas phase. This work aims to provide a theoretical basis for process optimization during the dephosphorization of 600 MPa steel.

Effect of Supports on Soot Oxidation of Copper Catalysts: BaTiO3 Versus Fe2O3@BaTiO3 Core/Shell Microsphere

NANO ◽  
2016 ◽  
Vol 11 (01) ◽  
pp. 1650010 ◽  
Author(s):  
Guoliang Fan ◽  
Liu Zhao ◽  
Cairong Gong ◽  
Jia Ma ◽  
Gang Xue
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Gas Flow ◽  
Copper Catalyst ◽  
Copper Catalysts ◽  
Core Shell ◽  
Phase Reaction ◽  
Soot Combustion ◽  
Supported Copper Catalyst

Copper catalysts prepared using two kinds of supports (BaTiO3 and Fe2O3@BaTiO[Formula: see text] have been tested for soot combustion. Perovskite-type oxide BaTiO3 shows excellent properties as support but has small specific surface area. Fe2O3@BaTiO3 core/shell microspheres, as improved support of BaTiO3 support, were fabricated by a hydrothermal-annealing approach. Fe2O3@BaTiO3 support has large specific surface area, which optimizes the contact condition of the gas-soot-catalyst three-phase reaction. Due to the Cu-Fe2O3@BaTiO3 interaction, the redox properties of copper are improved. Soot combustion is tested under O2 gas flow and NOx/O2 gas flow, and Fe2O3@BaTiO3 supported copper catalyst (Cu/Fe2O3@BaTiO[Formula: see text] all shows higher catalytic activity and CO2 selectivity than BaTiO3 supported copper catalyst (Cu/BaTiO[Formula: see text].

PENGARUH LAJU ALIR LPG (SEBAGAI BAHAN BAKAR BURNER) TERHADAP KARAKTERISTIK NANOKOMPOSIT ZnO/Fe2O3 YANG DIBUAT MENGGUNAKAN FLAME SPRAY PYROLISIS

EKUILIBIUM ◽  
2011 ◽  
Vol 10 (1) ◽  
Author(s):  
Agus Purwanto ◽  
Arif Jumari ◽  
Sperisa Distantina
Keyword(s):  
Particle Size ◽  
Specific Surface ◽  
Spray Pyrolysis ◽  
Surface Area ◽  
Specific Surface Area ◽  
Flow Rate ◽  
Catalytic Performance ◽  
Side Product ◽  
Flame Spray Pyrolysis ◽  
Flame Spray

<p><strong><em>A</em></strong><strong><em>b</em></strong><strong><em>stract</em></strong>: <em>Biodiesel is produced through catalytic esterification process of vegetable oil and alcohol. Producing of biodiesel was much carried out using homogeneous catalyst (acid/base). These process had many disanvantages: high energy consumption, side product formed and complicated separation among side product and catalyst. ZnO as transesterification catalyst has given high yield. To improve the catalytic performance, surface area per mas of catalyst must be increased by decreasing size of particle. To ease separation between product and catalyst, magnetic behaviour should be added to the catalyst. Aims of research were to obtain nanocomposite ZnO/Fe</em><em>2</em><em>O</em><em>3   </em><em>and  determine  physical characteristic as  well  as  catalytic  and separation performance of nanocomposite ZnO/Fe</em><em>2</em><em>O</em><em>3</em><em>. Nanocomposite ZnO/Fe</em><em>2</em><em>O</em><em>3  </em><em>w</em><em>a</em><em>s synthesized by flame spray pyrolysis method. Assisted by carrier air precursor solution of Zn(NO</em><em>3</em><em>)</em><em>2  </em><em>and Fe(NO</em><em>3</em><em>)</em><em>3  </em><em>w</em><em>a</em><em>s nebulized and flowed to inner tube of burner. Nebulasation was carried out by varying carrier gas flow rate but at constant rate of nebulization. LPG gas dan oxidant air were flowed to the inner annulus and outer annulus, respectively. The solid produced was separated from gas by particle filter. Solid particle obtained was then examined by X Ray Defraction (XRD), FE-SEM and BET as wel as catalytic performance. The result of the research showed that crystalinity of particles increased by increasing LPG flow rate. Particle size of ZnO/Fe</em><em>2</em><em>O</em><em>3  </em><em>nanocomposite decreased by increasing LPG flow rate and size were dominantly between  50-100  nm.  A  part  of  particle was  flowerlike particle.  Specific  surface area    of ZnO/Fe</em><em>2</em><em>O</em><em>3 </em><em>nanocomposite increased by increasing LPG flow rate and its value were between </em><em>45-55 m</em><em>2</em><em>/gram.</em></p><p> <strong><em>K</em></strong><strong><em>eywords</em></strong>: <em>Tran-esterification, nanocomposite </em>ZnO/Fe2O3<em>,  flame spray pyrolysis,   carrier gas</em>, <em>particle size, morphology of particle, specific surface area</em></p>

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