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 Chemical and Physical Properties of the Al1-xFexPO4 System Prepared by the Coprecipitation Method. II. Surface Acidity, Textural Properties and Catalytic Activity

2002 ◽  
Vol 20 (8) ◽  
pp. 741-755 ◽  
Author(s):  
F.Sh. Mohamed
Keyword(s):  
Catalytic Activity ◽  
Calcination Temperature ◽  
Pore Volume ◽  
Pore Radius ◽  
Surface Acidity ◽  
Total Pore Volume ◽  
Textural Properties ◽  
Coprecipitation Method ◽  
Temperature Variations ◽  
Kinetics Of

A coprecipitation method for the preparation of Al1-xFexPO4 catalysts with x (or Fe/P ratio) = 0.0, 0.2, 0.4, 0.6 and 0.8 was developed. The samples were calcined at temperatures within the range 200–800°C. The surface structure, cumulative acidity, textural properties, and the catalytic activity and selectivity of the prepared samples towards isopropanol and cyclohexane conversion were studied using different techniques. The results showed that the freshly calcined samples consisted of an amorphous phase, a quartz-type and a tridymite-type phase depending on the calcination temperature. The total surface acidity decreased with FePO4 content or calcination temperature. Variations in the Fe/P ratio and the calcination temperature led to changes in both the surface area and total pore volume of the Al1-xFexPO4 samples. Increases in the Fe/P ratio and increasing calcination temperature led to increases in the pore radius. The catalytic activity and selectivity were significantly affected as the structures of the Al1-xFexPO4 catalysts varied. The kinetics of the reaction were also studied.

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.

scholarly journals ACTIVITY TEST AND REGENERATION OF NiMo/Z CATALYST FOR HYDROCRACKING OF WASTE PLASTIC FRACTION TO GASOLINE FRACTION

2010 ◽  
Vol 5 (3) ◽  
pp. 261-268 ◽  
Author(s):  
Rodiansono Rodiansono ◽  
Wega Trisunaryanti
Keyword(s):  
Natural Zeolite ◽  
Pore Radius ◽  
Total Pore Volume ◽  
Acid Sites ◽  
Gasoline Fraction ◽  
Total Acid ◽  
Average Pore ◽  
Average Pore Radius ◽  
Activity Test ◽  
Hydrogen Stream

Activity test and regeneration of NiMo/active natural zeolite catalyst for hydrocracking of waste plastic fraction of polyprophylene (PP) type have been carried out. The catalysts was prepared by loading Mo followed by Ni Metals onto the natural zeolite (Z) sample, then calcined at 500oC, oxidized and reduced at 400oC under nitrogen, oxygen and hydrogen stream, respectively. The characterization of catalysts including spesific surface area, average pore radius, and total pore volume were performed by gas sorption analyzer, amount of total acid sites was determined by gas sorption method, and acid site strength was confirmed by IR spectroscopy. The hydrocracking process was carried out in a semi-flow reactor system at 360 oC and catalyst:feed ratio 0.5 under hydrogen stream (150 mL/hour). The feed was vaporized from the pyrolisis reactor into the hydrocracking reactor. A liquid product was collected and analyzed by gas chromatography (GC) and gas chromatography-mass spectroscopy (GC-MS). The characterization results showed that spesific surface area, average pore radius, and total pore volume of the Z sample decreased after loading of the Ni and Mo metals. Amount of total acid sites of the NiMo/Z catalyst was higher than that of the Z sample. The activity of NiMo/Z catalyst decreased after several continously runs. Its regeneration produced the NiMo/Z reg catalyst with similar activity and selectivity to the fresh catalyst (NiMo/Z). The activity of catalysts at the optimum condition followed the order of NiMo/Z reg>NiMo/Z>Z (conversion of hydrocarbon C>12) and NiMo/Z reg>NiMo/Z>Z (total yield of gasoline fraction). The selectivity of catalysts for C7-C8 product followed the order of Z>NiMo/Z>NiMo/Z reg. Keywords: activity, polyprophylene, catalyst, gasoline fraction.

EFFECT OF MEAN PORE SIZE ON THE LOW-TEMPERATURE ADSORPTION OF NITROGEN ON ALUMINA

1960 ◽  
Vol 38 (6) ◽  
pp. 783-786 ◽  
Author(s):  
J. L. Blumenthal ◽  
S. Sourirajan ◽  
Ken Nobe
Keyword(s):  
Low Temperature ◽  
Pore Size ◽  
Pore Radius ◽  
Capillary Condensation ◽  
Pressure Ratio ◽  
Relative Pressure ◽  
The Third ◽  
Two Samples ◽  
Adsorption Of Nitrogen ◽  
The Mean

The effect of mean pore size on the low-temperature adsorption of nitrogen on two samples of alumina has been studied. The mean pore radius of one sample of alumina was 37 Å, and that of the other was 3100 Å. The two adsorption isotherms at −195.8 °C have been plotted in terms of the volume of gas adsorbed per square meter of surface area vs. relative pressure ratio. The data have been found to fall into three distinct regions. In the first region extending up to the relative pressure ratio of 0.3, the two isotherms are nearly identical. In the second region extending from the relative pressure ratio of 0.3 to 0.75, the isotherm for the small mean pore size alumina lies above that for the large mean pore size sample. In the third region extending from the relative pressure ratio of 0.75 up to saturation, the isotherm for the small mean pore size sample tends to level off whereas that for the large mean pore size sample rises rapidly with increase in the relative pressure ratio. The above experimental observations have been explained on the basis of capillary condensation.

scholarly journals The Effect of Calcium Doping on the Surface and Catalytic Properties of Cobaltic Oxide Catalysts

2003 ◽  
Vol 21 (3) ◽  
pp. 229-243 ◽  
Author(s):  
Nasr-Allah M. Deraz
Keyword(s):  
Activation Energy ◽  
Calcination Temperature ◽  
Calcium Oxide ◽  
Total Pore Volume ◽  
Textural Properties ◽  
Peroxide Decomposition ◽  
Cobaltic Oxide ◽  
Adsorption Of Nitrogen ◽  
Activation Energy Of Sintering ◽  
Calcium Doping

The effects of calcium oxide doping (0.75, 1.5 and 3 mol% CaO) and calcination temperature (400, 500, 600 and 700°C) on different surface properties of Co3O4 were investigated. The structural properties of pure and doped oxide samples were determined by XRD methods, the textural properties were investigated via the adsorption of nitrogen at −196°C while the hydrogen peroxide decomposition activity of the investigated solids was determined by oxygen gasometric measurement of the reaction kinetics at 20–40°C. The dissolution of calcium ions in the Co3O4 lattice at temperatures in the range 400–600°C was accompanied by a marked decrease in the mean hydraulic radii (rh) and an increase in the surface area (SBET) and total pore volume (Vp) of the prepared oxide samples. In contrast, doping at 700°C brought about a decrease in the SBET and Vp values of the investigated solids. The catalytic activity for H2O2 decomposition on cobaltic oxide calcined at 400–700°C was found to decrease considerably on doping with CaO. The activation energy for sintering (ΔEs) of the pure and doped solids was determined from the variation in their SBET values as a function of the calcination temperature of these solids. Calcium oxide treatment resulted in a 50% increase in the activation energy of sintering of cobaltic oxide solid calcined at 400–600°C. This increase reflects the role of CaO doping in hindering the sintering of cobaltic oxide.

Surface Studies and Nature of Active Sites of Supported Heteropolyacids as Catalysts in Methanol Dehydration

1994 ◽  
Vol 59 (4) ◽  
pp. 820-832 ◽  
Author(s):  
Amin Anwar ◽  
Ali Abdel-Ghaffar ◽  
Sameh Aboul-Fotouh ◽  
Ebeid Fikry
Keyword(s):  
Atmospheric Pressure ◽  
Active Sites ◽  
Pore Radius ◽  
Catalytic Properties ◽  
Flow System ◽  
Total Pore Volume ◽  
X Ray Diffraction ◽  
Active Centers ◽  
X Ray ◽  
The Mean

Different amounts of molybdo- and tungstophosphoric acids were supported on α-Al2O3 to get information about their surface and catalytic properties. The surface study revealed that surface area, total pore volume and the mean pore radius decreased as the acid content increased. X-Ray diffraction analysis showed that there is no interaction between the acid and α-Al2O3. Using a continuous flow system, methanol transformation was carried out under atmospheric pressure. Some experiments were made to determine the nature of active centers and reaction mechanism.

scholarly journals Surface and Catalytic Properties of NiO and Fe2O3 Solids

1997 ◽  
Vol 15 (8) ◽  
pp. 593-607 ◽  
Author(s):  
A. Abd. El-Aal ◽  
A.M. Ghozza ◽  
G.A. El-Shobaky
Keyword(s):  
Catalytic Activity ◽  
Calcination Temperature ◽  
Active Sites ◽  
Pore Radius ◽  
Total Pore Volume ◽  
Surface Characteristics ◽  
Oxidation Of Co ◽  
Catalytic Activities ◽  
Catalytically Active ◽  
The Mean

The surface characteristics, viz., the specific surface area SBET, the total pore volume Vp and the mean pore radius r̄, of NiO and Fe2O3 were determined from N2 adsorption isotherms conducted at −196°C for the different adsorbents preheated in air at temperatures in the range 300–800°C. The catalytic activities exhibited in CO oxidation by O2 on the various solids were investigated at temperatures varying between 150°C and 400°C. The effect of heating the NiO and Fe2O3 solids in CO and O2 atmospheres at 175–275°C on their catalytic activities was also studied. The results showed that increasing the calcination temperature in the range 300–800°C resulted in a progressive decrease in the SBET value of NiO and Fe2O3. The computed values of the apparent activation energy for the sintering of the oxides were 71 and 92 kJ/mol, respectively. The sintering of NiO and Fe2O3 took place mainly via a particle adhesion mechanism. The catalytic activity of NiO decreased progressively on increasing its calcination temperature from 300°C to 800°C, due to a decrease in its SBET value and the progressive removal of excess O2 which was present as non-stoichiometric NiO. This treatment also decreased the catalytic activity of Fe2O3. The decrease was, however, more pronounced when the temperature increased from 300°C to 400°C which was a result of the crystallization of the ferric oxide into the α-Fe2O3 phase. An increase in the calcination temperature for both oxides from 300°C to 800°C did not modify the mechanism of oxidation of CO by O2 over the various solids but rather changed the concentration of catalytically active sites. Heating NiO and Fe2O3 in CO and O2 atmospheres at 175–275°C modified their catalytic activities, with Fe2O3 being influenced to a greater extent than NiO.

scholarly journals MCM-22, MCM-36, and ITQ-2 Zeolites with Different Si/Al Molar Ratios as Effective Catalysts of Methanol and Ethanol Dehydration

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2399 ◽  
Author(s):  
Monika Marosz ◽  
Bogdan Samojeden ◽  
Andrzej Kowalczyk ◽  
Małgorzata Rutkowska ◽  
Monika Motak ◽  
...  
Keyword(s):  
Surface Acidity ◽  
Surface Concentration ◽  
Acid Sites ◽  
Zeolite Framework ◽  
Catalytic Systems ◽  
Molar Ratios ◽  
Different Types ◽  
Ft Ir ◽  
Alcohol Conversion ◽  
N2 Sorption

MCM-22, MCM-36, and ITQ-2 zeolites with the intended Si/Al molar ratios of 15, 25, and 50 were synthetized and tested as catalysts for dehydration of methanol to dimethyl ether and dehydration of ethanol to diethyl ether and ethylene. The surface concentration of acid sites was regulated by the synthesis of zeolite precursors with different aluminum content in the zeolite framework, while the influence of porous structure on the overall efficiency of alcohol conversion was analyzed by application of zeolitic materials with different types of porosity—microporous MCM-22 as well as microporous-mesoporous MCM-36 and ITQ-2. The zeolitic samples were characterized with respect to their: chemical composition (ICP-OES), structure (XRD, FT-IR), texture (N2 sorption), and surface acidity (NH3-TPD). Comparison of the catalytic activity of the studied zeolitic catalysts with other reported catalytic systems, including zeolites with the similar Si/Al ratio as well as γ-Al2O3 (one of the commercial catalysts for methanol dehydration), shows a great potential of MCM-22, MCM-36, and ITQ-2 in the reactions of alcohols dehydration.

Characterization of Aminoalky Cellulose Adsorbent

2011 ◽  
Vol 287-290 ◽  
pp. 1365-1368
Author(s):  
Heng Zhu ◽  
Xiao Yan Lin ◽  
Xue Gang Luo ◽  
Ying Li
Keyword(s):  
Heavy Metal ◽  
Crystalline Phase ◽  
Pore Volume ◽  
Pore Diameter ◽  
Total Pore Volume ◽  
Decomposition Temperature ◽  
Ft Ir ◽  
The Mean ◽  
Cellulose Adsorbent

Aminoalky cellulose is a white, solid cellulose derivative, which could be used adsorbent in order to remove TNT, heavy metal and dyes due to the large of amino. In this paper, the preparation of aminoalky cellulose was reported, and the aminoalky cellulose was characterized by FT-IR, XRD, SEM and TG. The results showed that aminoalky cellulose was successfully prepared, an amorphous phase and a crystalline phase are included in the AmAC, and the decomposition temperature of AmAC was 288.23°C. Some surface properties of AmAC was measured, and the mean pore diameter and total pore volume of the AmAC is about 260.409 Å and 0.363827 cm3 g-1, respectively.

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.

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