scholarly journals Effect of Chemical Composition on the Structure and Catalytic Behaviour of AlPO4 and Al2O3–AlPO4 Mixed Catalysts

2002 ◽  
Vol 20 (2) ◽  
pp. 131-140 ◽  
Author(s):  
F.Sh. Mohamed ◽  
H.H. Kiwan ◽  
M.R. Mostafa
Keyword(s):  
Catalytic Activity ◽  
Chemical Composition ◽  
Surface Area ◽  
Surface Acidity ◽  
Total Pore Volume ◽  
Nitrogen Adsorption ◽  
X Ray Diffraction ◽  
Texture Surface ◽  
Pore Widening ◽  
Catalytic Behaviour

AlPO4 and Al2O3–AlPO4 mixed catalysts of different composition (Al/P > 1) were prepared and calcined in the temperature range 350–650°C. Such catalysts were characterized by DTA and X-ray diffraction methods, and by nitrogen adsorption studies at −196°C. Their acidity was determined using a calorimetric titration method while their catalytic activity towards the dehydration of isopropanol was determined using a pulse microcatalytic technique. The data obtained from XRD studies showed that pure AlPO4 when calcined at 650°C had a rather low crystallinity with its crystalline structure (which is of the α-cristobalite type) being characterized by poorly developed peaks. However, significant changes in the texture, surface acidity and catalytic activity were observed as a result of changing the chemical composition of the solid, with the surface area, total pore volume and surface acidity generally increasing with increasing alumina content. Sintering commenced above 550°C leading to a decrease in the surface area and to pore widening. Dehydration of isopropanol appeared to be insensitive to the structure of the catalysts investigated but was related to the surface acid density.

scholarly journals Effect of Sulfation on Zirconia-Pillared Montmorillonite to the Catalytic Activity in Microwave-Assisted Citronellal Conversion

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Is Fatimah ◽  
Dwiarso Rubiyanto ◽  
Thorikul Huda
Keyword(s):  
Catalytic Activity ◽  
Surface Acidity ◽  
Total Pore Volume ◽  
High Catalytic Activity ◽  
X Ray Diffraction ◽  
Adsorption Method ◽  
X Ray ◽  
Pillared Montmorillonite ◽  
Microwave Assisted ◽  
Tandem Cyclization

Preparation of sulfated zirconia-pillared montmorillonite was carried out in two steps; zirconia pillarization and sulfation to zirconia-pillared montmorillonite. The prepared materials were characterized by using X-ray diffraction (XRD), measurement of the specific surface area, total pore volume and pore size distribution by the N2adsorption method, scanning electron microscopy-energy dispersive X-ray (SEM-EDX), and surface acidity determination by using pyridine adsorption-FTIR analysis. The activity of the materials as catalysts was evaluated for a microwave-assisted conversion of citronellal. The results showed that the prepared materials had a physicochemical character that promoted high catalytic activity to convert citronellal. From varied Zr content and study of the effect of sulfation on the activity, it was found that Zr content and sulfation increase the surface acidity of the material as shown by the higher total conversion and tendency to produce menthol as a product of the tandem cyclization-hydrogenation mechanism.

scholarly journals Effect of Calcination Temperature on the Synthesis of ZrO2-Pillared Saponite to Catalytic Activity in Menthol Esterification

2018 ◽  
Vol 16 (1) ◽  
pp. 8 ◽  
Author(s):  
Is Fatimah ◽  
Dwiarso Rubiyanto ◽  
Nanda Candra Kartika
Keyword(s):  
Catalytic Activity ◽  
Surface Area ◽  
Calcination Temperature ◽  
Surface Acidity ◽  
Physicochemical Characteristics ◽  
Sem Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Calcination Temperatures ◽  
Solid Acidity

The influence of calcination temperature on the synthesis of zirconia-pillared saponite (PILS) and on its catalytic activity in menthol esterification has been studied. Zirconia pillarization was conducted using zirconium tetraisopropoxide as a precursor and with calcination temperatures of 450, 600 and 700 °C. Evaluation of physicochemical characteristics at these varied temperatures was carried out by X-Ray Diffraction (XRD), surface area analysis, Scanning Electron Eicroscope (SEM) analysis, Differential Thermal Analysis (DTA) and total acidity. The obtained results indicate that the structure and surface acidity of saponite were strongly influenced by calcination temperature. The solid acidity and surface parameters such as specific surface area, pore volume, and pore radius play an important role in the total conversion and selectivity in menthol esterification.

scholarly journals Surface Characterization and Catalytic Activity of Alumina and Alumina-Supported ZnSO4 Catalysts Prepared from Different Alumina Sources

2002 ◽  
Vol 20 (7) ◽  
pp. 695-705
Author(s):  
Farid Sh. Mohamed
Keyword(s):  
Catalytic Activity ◽  
Surface Characterization ◽  
Surface Acidity ◽  
Catalyst Activity ◽  
Total Pore Volume ◽  
Acid Sites ◽  
Aluminium Chloride ◽  
Impregnation Method ◽  
X Ray Diffraction ◽  
Ft Ir

Three alumina samples were prepared from different sources including aluminium isopropoxide, aluminium chloride and aluminium nitrate, and were then used to prepare supported ZnSO4 catalysts via the impregnation method. The alumina and ZnSO4-supported samples were characterized by X-ray diffraction (XRD), FT-IR spectroscopy and nitrogen physisorption methods. Dehydration of 1-butanol and the cracking of cumene were undertaken over the prepared samples using a pulse microcatalytic technique. For a given alumina sample, the surface area and total pore volume decreased continuously with increasing ZnSO4 content. Loading alumina samples with ZnSO4 improved their dehydration and cracking activities. The source of alumina played a role in determining the surface acidity and catalyst activity of alumina and alumina-supported ZnSO4 catalysts. Impregnation of ZnSO4 on alumina samples resulted in an increase in the concentration of Lewis sites and the creation of Brönsted acid sites on their surfaces. The catalytic activity of the investigated catalysts was found to depend strongly on both the chemical composition and the type of acid site present on the catalyst surface.

Environmentally Friendly Catalyst of Zirconium Pillared Saponite for Solvent Free Esterification of Menthol

2015 ◽  
Vol 1101 ◽  
pp. 272-275
Author(s):  
Is Fatimah
Keyword(s):  
Catalytic Activity ◽  
Specific Surface ◽  
Surface Area ◽  
Pore Volume ◽  
Surface Acidity ◽  
Sol Gel ◽  
Measurement Techniques ◽  
Pyridine Adsorption ◽  
X Ray Diffraction ◽  
X Ray

In this research zirconium pillared saponite clay (Zr-PILS) was prepared for catalysis application. Pillarization was conducted by zirconium isopropoxide via using sol-gel mechanism and the characterization was performed by X-ray diffraction, gas sorption analysis and surface acidity measurement by pyridine adsorption-FTIR measurement techniques. Result showed that pillaring process to saponite produced pillared saponite with increasing specific surface area, pore volume as well as surface acidity that contributed to enhance catalytic activity in menthol esterification. Reusability test was also showed that Zr-PILS activity is relatively stable.

scholarly journals Nanometer Pore Structure Characterization of Taiyuan Formation Shale in the Lin-Xing Area Based on Nitrogen Adsorption Experiments

Minerals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 298
Author(s):  
Chenlong Ding ◽  
Jinxian He ◽  
Hongchen Wu ◽  
Xiaoli Zhang
Keyword(s):  
Specific Surface ◽  
Pore Structure ◽  
Surface Area ◽  
Specific Surface Area ◽  
Shale Gas ◽  
Pore Volume ◽  
Ordos Basin ◽  
Total Pore Volume ◽  
Nitrogen Adsorption ◽  
Taiyuan Formation

Ordos Basin is an important continental shale gas exploration site in China. The micropore structure of the shale reservoir is of great importance for shale gas evaluation. The Taiyuan Formation of the lower Permian is the main exploration interval for this area. To examine the nanometer pore structures in the Taiyuan Formation shale reservoirs in the Lin-Xing area, Northern Shaanxi, the microscopic pore structure characteristics were analyzed via nitrogen adsorption experiments. The pore structure parameters, such as specific surface area, pore volume, and aperture distribution, of shale were calculated; the significance of the pore structure for shale gas storage was analyzed; and the main controlling factors of pore development were assessed. The results indicated the surface area and hole volume of the shale sample to be 0.141–2.188 m2/g and 0.001398–0.008718 cm3/g, respectively. According to the IUPAC (International Union of Pure and Applied Chemistry) classification, mesopores and macropores were dominant in the pore structure, with the presence of a certain number of micropores. The adsorption curves were similar to the standard IV (a)-type isotherm line, and the hysteresis loop type was mainly similar to H3 and H4 types, indicating that most pores are dominated by open type pores, such as parallel plate-shaped pores and wedge-shaped slit pores. The micropores and mesopores provide the vast majority of the specific surface area, functioning as the main area for the adsorption of gas in the shale. The mesopores and macropores provide the vast majority of the pore volume, functioning as the main storage areas for the gas in the shale. Total organic carbon had no notable linear correlation with the total pore volume and the specific surface area. Vitrinite reflectance (Ro) had no notable correlation with the specific surface area, but did have a low “U” curve correlation with the total pore volume. There was no relationship between the quartz content and specific surface area and total pore volume. In addition, there was no notable correlation between the clay mineral content and total specific surface area and total pore volume.

scholarly journals Characterization and Catalytic Behaviour of Co3(PO4)2–AlPO4 Catalysts

1998 ◽  
Vol 16 (4) ◽  
pp. 285-293 ◽  
Author(s):  
M.R. Mostafa ◽  
F.Sh. Ahmed
Keyword(s):  
Pore Radius ◽  
Surface Acidity ◽  
Total Pore Volume ◽  
Textural Properties ◽  
Acid Sites ◽  
Adsorption Of Nitrogen ◽  
Amorphous Structures ◽  
Ft Ir ◽  
Catalytic Behaviour ◽  
The Mean

Co3(PO4)2, AlPO4 and the binary system Co3(PO4)2-AlPO4 with different compositions were prepared by the coprecipitation method. The structural properties of these samples were determined using XRD, DTA and FT-IR techniques. The textural properties were determined from the adsorption of nitrogen at 77 K. The surface acidity was measured by a calorimetric titration method. The samples were tested as catalysts in the dehydration of ethanol and isopropanol using a pulse microcatalytic technique. The data obtained from XRD and FT-IR indicate the amorphous structures of the prepared catalysts. An increase in Co3(PO4)2 content led to a decrease in the surface area and in the total pore volume and an increase in the mean pore radius. The surface acidity of the catalyst depends on the chemical composition; the surface acidity increased with an increase in the AlPO4 content. The dehydration temperature and the distribution of acid sites are important parameters in determining the selectivity and activity of the catalyst.

scholarly journals Surface and Catalytic Properties of γ-Irradiated Cr2O3/Al2O3 Solids

1997 ◽  
Vol 15 (6) ◽  
pp. 465-476 ◽  
Author(s):  
G.A. El-Shobaky ◽  
A.M. Ghozza ◽  
G.M. Mohamed
Keyword(s):  
Catalytic Activity ◽  
Co Oxidation ◽  
Surface Area ◽  
Pore Volume ◽  
Active Sites ◽  
Catalytic Properties ◽  
Total Pore Volume ◽  
Bet Surface Area ◽  
Two Samples ◽  
Γ Rays

Two samples of Cr2O3/Al2O3 were prepared by mixing a known mass of finely powdered Al(OH)3 with a calculated amount of CrO3 solid followed by drying at 120°C and calcination at 400°C. The amounts of chromium oxide employed were 5.66 and 20 mol% Cr2O3, respectively. The calcined solid specimens were then treated with different doses of γ-rays (20–160 Mrad). The surface and catalytic properties of the different irradiated solids were investigated using nitrogen adsorption at −196°C and the catalysis of CO oxidation by O2 at 300–400°C. The results revealed that γ-rays brought about a slight decrease in the BET surface area, SBET (15%), and in the total pore volume, Vp (20%), of the adsorbent containing 5.66 mol% Cr2O3. The same treatment increased the total pore volume, Vp (36%), and the mean pore radius, r̄ (43%), of the other adsorbent sample without changing its BET surface area. The catalytic activities of both catalyst samples were found to increase as a function of dose, reaching a maximum value at 80–160 Mrad and 40 Mrad for the solids containing 5.66 and 20 mol% Cr2O3, respectively. The maximum increase in the catalytic activity measured at 300°C was 59% and 100% for the first and second catalyst samples, respectively. The induced effect of γ-irradiation on the catalytic activity was an increase in the concentration of catalytically active sites taking part in chemisorption and in the catalysis of CO oxidation by O2 without changing their energetic nature. This was achieved by a progressive removal of surface hydroxy groups during the irradiation process.

Investigation of ZnO/CuO/Nanographene Platelets Composites Catalyst for the Degradation of Methylene Blue from Aqueous Solution

2016 ◽  
Vol 864 ◽  
pp. 117-122 ◽  
Author(s):  
Hesni Shabrany ◽  
Hendry Tju ◽  
Ardiansyah Taufik ◽  
Rosari Saleh
Keyword(s):  
Aqueous Solution ◽  
Methylene Blue ◽  
Catalytic Activity ◽  
Visible Light ◽  
Sol Gel ◽  
Nitrogen Adsorption ◽  
Ultrasound Irradiation ◽  
X Ray Diffraction ◽  
X Ray

This paper discusses the catalytic activity of ZnO/CuO/nanographene platelets composites under visible light and ultrasound irradiation separately. The ZnO/CuO/nanographene platelets composites were synthesized using a sol-gel method. X-ray diffraction and nitrogen adsorption spectroscopy were employed to investigate the structural and surface area of the catalyst. The catalytic activity results showed that the presence of nanographene platelets in ZnO/CuO nanocomposites improved its efficiency in degrading methylene blue. A scavenger method was also used to understand the role of charged carriers and the active radical involved in the catalytic activity.

Sign in / Sign up

Export Citation Format

Share Document