Effect of Calcination Conditions on Crystalline Structure and Pore Size Distribution for a Mesoporous Alumina

Ravanchi, Maryam Takht; Fard, Maryam Rahimi; Fadaeerayeni, Siavash; Yaripour, Fereidoon

doi:10.1080/00986445.2013.850577

Cited by 24 publications

(11 citation statements)

References 37 publications

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“…Earlier research on the development of ceramic membranes has been focused on the optimization of sintering temperature and selection of alternative low-cost raw materials [21,22]. However, the role of carbonates as pore-forming agents in the fabrication of porous membranes cannot be ignored.…”

Section: Desalination and Water Treatmentmentioning

confidence: 99%

Preparation of kaolin-based low-cost porous ceramic supports using different amounts of carbonates

Kaur

Bulasara

Gupta

2016

Desalination and Water Treatment

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A B S T R A C TFlat ceramic membrane supports were prepared using kaolin as the major constituent with varying amounts of carbonates and sintered at 900˚C. The prepared supports were subjected to SEM, XRD, and porosity tests. The supports prepared without using carbonates had the largest mean pore size with the lowest porosity. The porosity of membranes increased by increasing the amount of calcium carbonate. The supports prepared using calcium carbonate had wider pore size distribution on the surface than those prepared using sodium carbonate. Small amount (10%) of sodium carbonate acts as a pore modifier resulting in smaller mean pore size, while large amount (>20%) of sodium carbonate blocks the pores by forming a sodium silicate layer and results in nonporous support. Therefore, calcium carbonate should be preferred over sodium carbonate for preparing highly porous ceramic membranes.

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Section: Desalination and Water Treatmentmentioning

confidence: 99%

Preparation of kaolin-based low-cost porous ceramic supports using different amounts of carbonates

Kaur

Bulasara

Gupta

2016

Desalination and Water Treatment

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“…The broad peaks of γ ‐Al 2 O 3 imply low crystallinity of the sample. In contrast, the sharp peaks of the calcined support indicate relatively large crystallites and well‐defined long‐range order in the corundum, which signifies the collapse of the porous structure characteristic of the low‐temperature aluminas and the consequent reduction of surface area 8.…”

Section: Resultsmentioning

confidence: 95%

“…The catalysts investigated in this work are used in the so‐called C 2 tail‐end selective hydrogenation 8 where the following reactions take place: C 2 H 2 + H 2 → C 2 H 4 Δ G o 298 = −141 kJ mol −1 , Δ H o 298 = −172 kJ mol −1 C 2 H 4 + H 2 → C 2 H 6 Δ G o 298 = −101 kJ mol −1 , Δ H o 298 = −136 kJ mol −1 C 2 H 2 + 2H 2 → C 2 H 6 Δ G o 298 = −242 kJ mol −1 , Δ H o 298 = −308 kJ mol −1 n C 2 H 2 + m H 2 → green oil and coke …”

Section: Introductionmentioning

confidence: 99%

Pd‐Ag/α‐Al₂O₃ Catalyst Deactivation in Acetylene Selective Hydrogenation Process

Ravanchi¹,

Sahebdelfar²,

Fard³

et al. 2016

Chem Eng & Technol

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The selective hydrogenation of acetylene to ethylene over Pd‐Ag/α‐Al2O3 catalysts prepared by different impregnation/reduction methods was studied. The best catalytic performance was achieved with the sample prepared by sequential impregnation. A kinetic model based on first order in acetylene and 0.5th order in hydrogen for the main reaction and second‐order independent decay law for catalyst deactivation was used to fit the conversion time data and to obtain quantitative assessment of catalyst performances. Fair fits were observed from which the reaction and deactivation rate constants were evaluated. Coke deposition amounts showed a good correlation with catalyst deactivation rate constants, indicating that coke formation should be the main cause of catalyst deactivation.

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“…The mean crystal size of Al 2 O 3 support was estimated by the half-width of the corresponding XRD peaks using Scherrer equation [18].…”

Section: Characterizationmentioning

confidence: 99%

Influence of calcination parameters on the properties of alumina as a catalyst support

Komeili

Ravanchi²,

Taeb

2016

Scientia Iranica

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Abstract. The preparation history of Al 2 O 3 strongly determines its properties for the application as a catalyst support. The interaction of calcination heating rate and temperature and its in uence on the structural, textural, and acidic properties of alumina were studied. Commercial -alumina was calcined at 800 C, 900 C, 1000 C, 1050 C, 1100 C, and 1150 C by 2.5 C/min, 5 C/min, and 10 C/min. By increasing temperature up to 1050 C, transition aluminas ( , , and ) were reported, but the heating rate accelerated phase transformation and changed the amount of each phase in the samples. At 1100 C and 1150 C, -alumina appeared. Mesopore alumina with di erent surface areas (265-126 m 2 /g) was synthesized at calcination temperature from 800 C to 1050 C; when temperature reached 1100 C, the surface area decreased drastically and was around 14 m 2 /g. Interaction of heating rate on the temperature had minimal e ect on the surface area of samples, but considerable e ect on the acidic properties. The intensity of acidic properties was a ected by heating rate with nonlinear pro les. By increasing the heating rate, the ratio of Al cations occupied tetrahedral per octahedral sites and defect of crystal structures increased, so the surface acidity of aluminas was increased.

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Effect of Calcination Conditions on Crystalline Structure and Pore Size Distribution for a Mesoporous Alumina

Cited by 24 publications

References 37 publications

Preparation of kaolin-based low-cost porous ceramic supports using different amounts of carbonates

Preparation of kaolin-based low-cost porous ceramic supports using different amounts of carbonates

Pd‐Ag/α‐Al₂O₃ Catalyst Deactivation in Acetylene Selective Hydrogenation Process

Influence of calcination parameters on the properties of alumina as a catalyst support

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Effect of Calcination Conditions on Crystalline Structure and Pore Size Distribution for a Mesoporous Alumina

Cited by 24 publications

References 37 publications

Preparation of kaolin-based low-cost porous ceramic supports using different amounts of carbonates

Preparation of kaolin-based low-cost porous ceramic supports using different amounts of carbonates

Pd‐Ag/α‐Al2O3 Catalyst Deactivation in Acetylene Selective Hydrogenation Process

Influence of calcination parameters on the properties of alumina as a catalyst support

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Product

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Pd‐Ag/α‐Al₂O₃ Catalyst Deactivation in Acetylene Selective Hydrogenation Process