Evolution of pore surface area during noncatalytic gas-solid reactions. 2. Experimental results and model validation

Ballal, Girish; Zygourakis, Kyriacos

doi:10.1021/ie00069a012

Cited by 58 publications

(48 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Based upon our results, we concur that the choice of temperature and reactant gas concentration should have little effect, provided that operation remains under Zone I conditions. Differences in variation of reactivity with burn-off for O 2 and CO 2 have been noted previously [8]. In that earlier study, the patterns exhibited by another Pittsburgh No.…”

Section: Relationship Of Surface Area To Reaction Ratesupporting

confidence: 49%

“…The general interpretation is that the surface area for reaction initially increases with burn-off, and then is lost as a result of pore coalescence. In one study [8], the patterns of porosity development were shown to depend upon the combination of reactant gas and char, but were independent of temperature and reactant gas concentration. Based upon our results, we concur that the choice of temperature and reactant gas concentration should have little effect, provided that operation remains under Zone I conditions.…”

Section: Relationship Of Surface Area To Reaction Ratementioning

confidence: 99%

“…These observations led to a conclusion that micropore area might not be fully utilized in the case of oxygen gasification [8]. The possibility that there is an inability to fully utilize micropores has been cited by many workers in the field [3-5, 7,11].…”

Section: Relationship Of Surface Area To Reaction Ratementioning

confidence: 99%

“…The proper design of combustion facilities demands that the kinetics of combustion be understood. Much combustion literature suggests that char reactivities should be expressed on a surface area basis [2], although small char micropores might not be fully utilized during oxidation or gasification [e.g., [3][4][5][6][7][8]. Many models have been proposed to describe development of char surface areas with burn-off [9][10][11][12][13][14][15], but many features need further clarification -e.g., different patterns of porosity development are observed in the same char, in different gases, even when rates of reaction are set to be identical [7,16].…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Study of Activation of Coal Char

Suuberg¹,

Kulaots²,

Aarna³

et al. 2003

View full text Add to dashboard Cite

Section: Relationship Of Surface Area To Reaction Ratesupporting

confidence: 49%

Section: Relationship Of Surface Area To Reaction Ratementioning

confidence: 99%

Section: Relationship Of Surface Area To Reaction Ratementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Study of Activation of Coal Char

Suuberg¹,

Kulaots²,

Aarna³

et al. 2003

View full text Add to dashboard Cite

“…The rate of reaction increased gradually between 0 and 70 wt % of gasification and decreased between 70 and 80 wt %. This trend of apparent reaction rate exhibiting a maximum has often been remarked in carbon consumption studies in the literature [32,[44][45][46][47]. Bhatia and Perlmutter [46] and Ballal and Zygouraki [47] explained the maximum rate with the combination of two opposite effects: the augmentation of the reactive surface with pore growth and pore accessibility, and the disappearance of this surface area with pore coalescence and consumption of carbon material.…”

Section: Thermo-gravimetric (Tg) Analysissupporting

confidence: 68%

Evolution of Anode Porosity under Air Oxidation: The Unveiling of the Active Pore Size

Chevarin

Ishak

Ziegler

et al. 2017

Metals

View full text Add to dashboard Cite

Abstract:The carbon anode, used in aluminum electrolysis (Hall-Héroult process), is over-consumed by air oxidation and carboxy-reaction (with CO 2 ). Several anode features may affect this over-consumption, such as impurity content, graphitization level and anode porosity features (e.g., porosity volume fraction or pore size distribution). The two first parameters are basically related to the quality of raw materials and coke calcination conditions. Anode porosity is, however, greatly affected by anode manufacturing conditions, and is possible to be modified, to some extent, by adjusting the anode recipe and the processing parameters. This work aims to investigate the effect of anode porosity on its air reactivity. Baked anode samples were prepared in laboratory scale and then crushed into powder form (−4760 + 4000 µm). The recipe for anode preparation was similar to a typical industrial recipe, except that in the lab scale no butt particles were used in the recipe. Anode particles were then gasified at six different conversion levels (0, 5, 15, 25, 35 and 50 wt %) under air at 525 • C. The porosity was characterized in several pore size ranges, measured by nitrogen adsorption and mercury intrusion (0.0014-0.020, 0.002-0.025, 0.025-0.100, 0.1-40.0 and superior at 40 µm). The volume variation of each pore range, as a function of carbon conversion, was assessed and used to determine the size of the most active pores for air oxidation. The most active pore size was found to be the pores inferior at 40 µm before 15 wt % of gasification and pores superior at 40 µm between 15 and 50 wt % of carbon conversion. Limitation of pore size range could be used as an additional guideline, along with other targets such as high homogeneity and density, to set the optimum anode manufacturing parameters.

show abstract

A nanoscale model for characterizing the complex pore structure of biochars

2013

Self Cite

View full text Add to dashboard Cite

The development of a novel nanoscale model that can accurately describe the reactivity of solids consisting of multiple components and having ordered and random pores is presented. Domains of multiple solid phases are distributed on a computational grid to simulate reactants with different specific reactivities and dispersions. Sub‐nanometer slit pores and larger cylindrical pores with given size distributions are also distributed on the grid in regular and random arrangements respectively. The generated solids are then eroded using rules that simulate a gas‐solid, non‐catalytic reaction occurring in the kinetic control regime. A parametric study is first carried out to demonstrate how key pore structural parameters affect the reactivity patterns. Model predictions are found to be in excellent agreement with experimental thermogravimetric data for the combustion of biochars, both when the slit and random cylindrical pores are fully accessible to the reactant and when diffusional limitations appear in the smaller slit pores. © 2013 American Institute of Chemical Engineers AIChE J, 59: 3412–3420, 2013

show abstract

Evolution of pore surface area during noncatalytic gas-solid reactions. 2. Experimental results and model validation

Abstract: The solid curves in Figure 15 represent the calculated time dependences of unconverted fraction of sulfide by eq 15 and 16. The values of reaction rate constants ki and ku and catalyst fouling parameter 0 were selected so that Literature Cited

Cited by 58 publications

References 6 publications

Study of Activation of Coal Char

Study of Activation of Coal Char

Evolution of Anode Porosity under Air Oxidation: The Unveiling of the Active Pore Size

A nanoscale model for characterizing the complex pore structure of biochars

Contact Info

Product

Resources

About