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Papers by abd ellilah said
Nanoscience and Nanoengineering, 2014
A series of single and mixed oxides of nano CuO-NiO were prepared by thermal decomposition of the... more A series of single and mixed oxides of nano CuO-NiO were prepared by thermal decomposition of the NiC 2 O 4 .2H 2 O and/or CuC 2 O 4 precursors which obtained via the reaction between alcoholic metal nitrates and oxalic acid solutions. Thermal behavior of the single and mixed salts has been studied using thermal analysis (TG and DTA). Thermal products were characterized using Fouier transform infrared (FTIR), X-ray diffraction (XRD), Electron microscopy (SEM&TEM), Nitrogen adsorption at-196 o C and surface excess oxygen measurements. The results revealed that, pure NiC 2 O 4 .2H 2 O and CuC 2 O 4 decomposed at 355 and 325 o C, respectively. Also, it was found that the addition of NiO to CuO brought a significant increase in the degree of crystallinity of the mixed oxides which is accompanying with an increase in their particle size and a decrease in the surface area. Moreover, addition of NiO to CuO, also reduces the amount of surface excess oxygen of CuO due to a synergistic effect.
Journal of Chemical Technology and Biotechnology, 2007
Background: Diabetes mellitus with its accompanying vascular complications is on a rise globally ... more Background: Diabetes mellitus with its accompanying vascular complications is on a rise globally and a similar trend has been observed in Libya too. Early detection, effective monitoring and timely management is important to control this growing problem. Various studies have shown microalbuminuria as an early indicator of nephropathy in diabetes mellitus. e present study is aimed at evaluating microalbuminuria and HbA1C in type 2 diabetes mellitus.
Clinical Chemistry and Laboratory Medicine
BACKGROUND: Homocysteine is an amino acid derivative of S-Adenosyl methionine, which is sulfated ... more BACKGROUND: Homocysteine is an amino acid derivative of S-Adenosyl methionine, which is sulfated to form cysteine. Thus homocysteine has gained importance as an early marker of atherosclerosis leading to vascular diseases. Hence the objective of the current study is to evaluate the association of high plasma homocysteine with atherosclerosis based on a comparative study on patients diagnosed with type 2 diabetes mellitus with and without complications. METHODS: This study was carried out using the laboratory data of sixty subjects from 30 to 75 years old. The data was collected from the samples sent from the outpatients of Diabetes Clinic, 17th February Hospital, El Baida. The study drawn were categorized into three groups: The control group comprised of twenty age matched healthy volunteers with no history of diabetes mellitus. The second group comprised of diabetics with no history of coronary artery disease and the third category comprising of twenty patients with a long history ...
Research on Chemical Intermediates, 2015
A series of ZrO 2 /c-Al 2 O 3 catalysts were prepared by incipient wetness impregnation of zircon... more A series of ZrO 2 /c-Al 2 O 3 catalysts were prepared by incipient wetness impregnation of zirconyl nitrate hydrate aqueous solutions on nano-c-Al 2 O 3 with ZrO 2 loadings (1-30 % w/w) and calcined at 450 and 550°C for 3 h in a static air atmosphere. Physicochemical properties of the catalysts were determined using TG, DTA, XRD, FT-IR, Raman spectroscopy, TEM, and N 2 sorption measurements. The surface acidity of the catalysts was investigated by dehydration of isopropanol and adsorption of pyridine, 2,6-dimethyl pyridine and TPD-pyridine. This series of catalysts was used for vapor-phase dehydration of methanol to dimethyl ether in a fixed bed reactor. It was found that all catalysts in this study were active and selective for DME synthesis. According to the experimental results, 1 % ZA catalyst exhibited the highest activity with selectivity of 100 % toward DME.
Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering, 2010
In this paper, we analyzed the multi-carrier direct sequence code division multiple access system... more In this paper, we analyzed the multi-carrier direct sequence code division multiple access system when the received signal is divided into predetermined spreading sequences, and the sub-bands are modulated over M carriers. Because of the unknown phase of the received signal at each sub-band the receiver cannot coherently combine the outputs of the correlators. We consider in this paper non-coherent combining scheme (equal gain combining) with MAI interferences. The calculation of the probabilities of detection and false alarm for both multicarrier (MC) and single carrier (SC) system in a Rayleigh fading channel demonstrated that the performances of the multicarrier system are better than those with single carrier system. Obtained results demonstrated that the suppression (or the mitigation) of appeared interferences is obtained by the increase of the number of system carriers 1 .
Surface Technology, 1984
The effect of doping on the catalytic behaviour of Cr203 was studied using the thermal decomposit... more The effect of doping on the catalytic behaviour of Cr203 was studied using the thermal decomposition of KCIO4 as a test reaction. The doping of the catalysts was effected using 5 mol.% Li ÷, Zr 4÷ or U 6÷ ions and calcination at 600 °C for 5 h. Studies were carried out using thermogravimetric analysis and electrical conductivity measurements. The results showed that Cr203 was more effective in enhancing the decomposition process when it was doped with U 6÷ ions than when it was doped with Li ÷ or Zr 4÷ ions. Mechanisms of doping were discussed and the role of defects in the catalytic reaction was interpreted.
Surface Technology, 1982
ABSTRACT The electrical conductivity of V2O5 catalysts doped and mixed with Fe3+, Co3+ and Ni2+ i... more ABSTRACT The electrical conductivity of V2O5 catalysts doped and mixed with Fe3+, Co3+ and Ni2+ ions in the concentration range 0.5–70 at.% was studied. Experiments were carried out in air as well as in the presence of 2-propanol in the feed. It has been shown that doping of V2O5 with foreign ions increases the hole concentration. The calculated ΔEa values shows that the addition of Ni2+ or Fe3+ ions increases slightly its p-type character while Co3+ ions increase strongly the p-type conductivity of V2O5 catalyst. These results were manifested on the addition of 2-propanol.
Journal of Molecular Catalysis A: Chemical, 2014
Sulfated zirconia catalysts were prepared by wetness impregnation of zirconium hydroxide with an ... more Sulfated zirconia catalysts were prepared by wetness impregnation of zirconium hydroxide with an aqueous solution of (NH4)2SO4 with SO42− loadings (1-30%, w/w) and calcined at 450 °C for 3 h in a static air atmosphere. The catalysts were characterized by FT-IR, XRD, TEM and BET measurements. The surface acidity of the catalysts was investigated by the dehydration of isopropanol and the adsorption of pyridine (PY) and 2,6-dimethyl pyridine (DMPY). The catalysts were tested for dehydration of methanol in a fixed-bed reactor at 230 °C using air as a carrier gas. The results revealed that among different catalysts, 10% SO42− supported onto zirconia showed the highest catalytic activity with 83% conversion and 100% selectivity toward dimethyl ether. A good correlation was found between the acidity of the catalysts and their ability to dehydrate methanol.
Thermochimica Acta, 1985
The effect of monovalent ions on the decomposition stages of ammonium metavanadate was studied us... more The effect of monovalent ions on the decomposition stages of ammonium metavanadate was studied using TG and electrical conductivity measurements. It has been determined that Li+ ions affect the decomposition process in a different manner from Na+ or K+ ions. The mechanism by which these ions affect the decomposition process is discussed in relation to the defect structure created by the doping process. EXPERIMENTAL
Thermochimica Acta, 1988
... 126 (1988) 17-24 17 Elsevier Science Publishers BV, Amsterdam - Printed in The Netherlands TH... more ... 126 (1988) 17-24 17 Elsevier Science Publishers BV, Amsterdam - Printed in The Netherlands THERMAL DECOMPOSITION OF KCIQ, CATALYZED BY MnO^-CuO MIXED OXIDES SYSTEMS AM EL-AWAD *, AA SAID ... 9 AA Said, EA Hassan and KM Abd El-Salaam, Surf. ...
Thermochimica Acta, 1985
ABSTRACT The enhancing influence of chromium oxide as a catalyst for the decomposition of KMnO4 h... more ABSTRACT The enhancing influence of chromium oxide as a catalyst for the decomposition of KMnO4 has been studied. Its action was attributed to the presence of surface holes in accepting the released electrons from the intermediate step. There is an indication that a solid-state interaction occurs between the catalyst and the products of decomposition. The reaction products were identified using IR spectroscopy. The inhibition of either Zr4+ or U6+ cations is attributed to the doping effect via the consumption of surface as well as bulk holes.
Monatshefte f�r Chemie / Chemical Monthly, 2004
A series of AlPO 4-V 2 O 5 (APV) systems with various vanadia amounts 1-30 mol% were prepared by ... more A series of AlPO 4-V 2 O 5 (APV) systems with various vanadia amounts 1-30 mol% were prepared by the impregnation method and calcinated at 400 and 600 C for 4 h. The catalysts were characterized by TG=DTG, DSC, IR spectroscopy, XRD, N 2 adsorption, and electrical conductivity measurements. The surface acidity and basicity of the catalysts were studied by the dehydrationdehydrogenation of isopropyl alcohol and the adsorption of pyridine. The catalytic gas phase esterification of acetic acid with ethyl alcohol was carried out at 210 C in a flow system at 1 atm using air as a carrier gas. The results showed that the catalysts calcinated at 400 C were active and selective towards the formation of ethyl acetate whereas the calcination of samples at 600 C led to a drastic reduction in both activity and selectivity. Good correlations were obtained between catalytic activities towards ester formation and acidity of the prepared catalysts.
Journal of Thermal Analysis, 1993
Thermal decomposition of pure Fe(OH)3 and mixed with Co(OH)2 were studied using TG, DTA, kinetics... more Thermal decomposition of pure Fe(OH)3 and mixed with Co(OH)2 were studied using TG, DTA, kinetics of isothermal decomposition and electrical conductivity measurements. The thermal products were characterized by X-ray diffraction and IR spectroscopy. The TG and DTA analysis revealed the presence of Co 2+ retards the decomposition of ferric hydroxide and the formation of 0~-Fe203. The kinetics of decomposition showed that the mixed samples need higher energy to achieve thermolysis. The investigation of thermal products of mixed samples indicated the formation of cobalt ferrite on addition of x = 1 or 1.5 cobalt hydroxide. The electrical conductivity accompanying the thermal decomposition decreases in presence of low ratio of Co z+ (x = 0.2) via the consumption of holes created during thermal analysis. The continuous increase in t~ values on in-. 2+ 9 9 2+ 3+ creasing of Co concentration corresponded to the electron hopping between Fe and Co .
Journal of Thermal Analysis, 1990
Thermal decomposition of pure basic zinc carbonate (BZC) and doped or mixed with iron ions were s... more Thermal decomposition of pure basic zinc carbonate (BZC) and doped or mixed with iron ions were studied using TG, DTA and kinetics of isothermal decomposition. The TG and DTA investigations revealed that, the presence of iron ions retards the decomposition processes of (BZC). Also, the retardation effect increases on increasing of iron concentration up to 50 at.%. The curves of
Journal of Chemical Technology & Biotechnology, 2003
... Correspondence: Abd El-Aziz A Said, Chemistry Department, Faculty of Science, Assiut Universi... more ... Correspondence: Abd El-Aziz A Said, Chemistry Department, Faculty of Science, Assiut University, Assiut, Egypt. Publication History. ... 11 Said AA and Khalil KMS, Catalytic decomposition of ethanol on V 2 O 5 AlPO 4 catalysts. J Chem Technol Biotechnol 75: 19 (2000). ...
Journal of Chemical Technology AND Biotechnology, 1995
Page 1. J. Chem. Tech. Biotechnol. 1995,63,78-84 Oxidative Dehydrogenation of Ethyl Alcohol over ... more Page 1. J. Chem. Tech. Biotechnol. 1995,63,78-84 Oxidative Dehydrogenation of Ethyl Alcohol over Vanadium Pentoxide Supported on Magnesia Abd El-Aziz A. Said* & Mohamed M. M. Abd El-Wahab Chemistry Department, Faculty of Science, Assiut University, Assiut, Egypt ...
Journal of Chemical Technology & Biotechnology, 2006
A series of MoO 3 /SiO 2 catalysts was prepared by an impregnation method with Mo loadings rangin... more A series of MoO 3 /SiO 2 catalysts was prepared by an impregnation method with Mo loadings ranging from 1 to 50 wt%. The original and calcined samples at 400 • C were characterized by thermogravimetry (TG), differential thermogravimetry (DTG), differential scanning calorimetry (DSC), X-ray diffraction (XRD), Fourier transform infra-red (FTIR) spectroscopy, and nitrogen adsorption measurements. The surface acidity and basicity of the catalysts were investigated by the dehydration-dehydrogenation of isopropanol and the chemisorption of pyridine. The catalytic esterification of acetic acid with ethanol was carried out at 220 • C in a conventional fixed-bed reactor at 1 atm using air as a carrier gas. The results clearly revealed that silica-molybdena catalysts were active and selective towards the formation of ethyl acetate. Moreover, the catalyst containing 20 wt% MoO 3 was the most active and selective one. The results emphasize the importance of the surface acid sites together with the specific surface area of the prepared catalyst, towards ester formation.
Nanoscience and Nanoengineering, 2014
A series of single and mixed oxides of nano CuO-NiO were prepared by thermal decomposition of the... more A series of single and mixed oxides of nano CuO-NiO were prepared by thermal decomposition of the NiC 2 O 4 .2H 2 O and/or CuC 2 O 4 precursors which obtained via the reaction between alcoholic metal nitrates and oxalic acid solutions. Thermal behavior of the single and mixed salts has been studied using thermal analysis (TG and DTA). Thermal products were characterized using Fouier transform infrared (FTIR), X-ray diffraction (XRD), Electron microscopy (SEM&TEM), Nitrogen adsorption at-196 o C and surface excess oxygen measurements. The results revealed that, pure NiC 2 O 4 .2H 2 O and CuC 2 O 4 decomposed at 355 and 325 o C, respectively. Also, it was found that the addition of NiO to CuO brought a significant increase in the degree of crystallinity of the mixed oxides which is accompanying with an increase in their particle size and a decrease in the surface area. Moreover, addition of NiO to CuO, also reduces the amount of surface excess oxygen of CuO due to a synergistic effect.
Journal of Chemical Technology and Biotechnology, 2007
Background: Diabetes mellitus with its accompanying vascular complications is on a rise globally ... more Background: Diabetes mellitus with its accompanying vascular complications is on a rise globally and a similar trend has been observed in Libya too. Early detection, effective monitoring and timely management is important to control this growing problem. Various studies have shown microalbuminuria as an early indicator of nephropathy in diabetes mellitus. e present study is aimed at evaluating microalbuminuria and HbA1C in type 2 diabetes mellitus.
Clinical Chemistry and Laboratory Medicine
BACKGROUND: Homocysteine is an amino acid derivative of S-Adenosyl methionine, which is sulfated ... more BACKGROUND: Homocysteine is an amino acid derivative of S-Adenosyl methionine, which is sulfated to form cysteine. Thus homocysteine has gained importance as an early marker of atherosclerosis leading to vascular diseases. Hence the objective of the current study is to evaluate the association of high plasma homocysteine with atherosclerosis based on a comparative study on patients diagnosed with type 2 diabetes mellitus with and without complications. METHODS: This study was carried out using the laboratory data of sixty subjects from 30 to 75 years old. The data was collected from the samples sent from the outpatients of Diabetes Clinic, 17th February Hospital, El Baida. The study drawn were categorized into three groups: The control group comprised of twenty age matched healthy volunteers with no history of diabetes mellitus. The second group comprised of diabetics with no history of coronary artery disease and the third category comprising of twenty patients with a long history ...
Research on Chemical Intermediates, 2015
A series of ZrO 2 /c-Al 2 O 3 catalysts were prepared by incipient wetness impregnation of zircon... more A series of ZrO 2 /c-Al 2 O 3 catalysts were prepared by incipient wetness impregnation of zirconyl nitrate hydrate aqueous solutions on nano-c-Al 2 O 3 with ZrO 2 loadings (1-30 % w/w) and calcined at 450 and 550°C for 3 h in a static air atmosphere. Physicochemical properties of the catalysts were determined using TG, DTA, XRD, FT-IR, Raman spectroscopy, TEM, and N 2 sorption measurements. The surface acidity of the catalysts was investigated by dehydration of isopropanol and adsorption of pyridine, 2,6-dimethyl pyridine and TPD-pyridine. This series of catalysts was used for vapor-phase dehydration of methanol to dimethyl ether in a fixed bed reactor. It was found that all catalysts in this study were active and selective for DME synthesis. According to the experimental results, 1 % ZA catalyst exhibited the highest activity with selectivity of 100 % toward DME.
Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering, 2010
In this paper, we analyzed the multi-carrier direct sequence code division multiple access system... more In this paper, we analyzed the multi-carrier direct sequence code division multiple access system when the received signal is divided into predetermined spreading sequences, and the sub-bands are modulated over M carriers. Because of the unknown phase of the received signal at each sub-band the receiver cannot coherently combine the outputs of the correlators. We consider in this paper non-coherent combining scheme (equal gain combining) with MAI interferences. The calculation of the probabilities of detection and false alarm for both multicarrier (MC) and single carrier (SC) system in a Rayleigh fading channel demonstrated that the performances of the multicarrier system are better than those with single carrier system. Obtained results demonstrated that the suppression (or the mitigation) of appeared interferences is obtained by the increase of the number of system carriers 1 .
Surface Technology, 1984
The effect of doping on the catalytic behaviour of Cr203 was studied using the thermal decomposit... more The effect of doping on the catalytic behaviour of Cr203 was studied using the thermal decomposition of KCIO4 as a test reaction. The doping of the catalysts was effected using 5 mol.% Li ÷, Zr 4÷ or U 6÷ ions and calcination at 600 °C for 5 h. Studies were carried out using thermogravimetric analysis and electrical conductivity measurements. The results showed that Cr203 was more effective in enhancing the decomposition process when it was doped with U 6÷ ions than when it was doped with Li ÷ or Zr 4÷ ions. Mechanisms of doping were discussed and the role of defects in the catalytic reaction was interpreted.
Surface Technology, 1982
ABSTRACT The electrical conductivity of V2O5 catalysts doped and mixed with Fe3+, Co3+ and Ni2+ i... more ABSTRACT The electrical conductivity of V2O5 catalysts doped and mixed with Fe3+, Co3+ and Ni2+ ions in the concentration range 0.5–70 at.% was studied. Experiments were carried out in air as well as in the presence of 2-propanol in the feed. It has been shown that doping of V2O5 with foreign ions increases the hole concentration. The calculated ΔEa values shows that the addition of Ni2+ or Fe3+ ions increases slightly its p-type character while Co3+ ions increase strongly the p-type conductivity of V2O5 catalyst. These results were manifested on the addition of 2-propanol.
Journal of Molecular Catalysis A: Chemical, 2014
Sulfated zirconia catalysts were prepared by wetness impregnation of zirconium hydroxide with an ... more Sulfated zirconia catalysts were prepared by wetness impregnation of zirconium hydroxide with an aqueous solution of (NH4)2SO4 with SO42− loadings (1-30%, w/w) and calcined at 450 °C for 3 h in a static air atmosphere. The catalysts were characterized by FT-IR, XRD, TEM and BET measurements. The surface acidity of the catalysts was investigated by the dehydration of isopropanol and the adsorption of pyridine (PY) and 2,6-dimethyl pyridine (DMPY). The catalysts were tested for dehydration of methanol in a fixed-bed reactor at 230 °C using air as a carrier gas. The results revealed that among different catalysts, 10% SO42− supported onto zirconia showed the highest catalytic activity with 83% conversion and 100% selectivity toward dimethyl ether. A good correlation was found between the acidity of the catalysts and their ability to dehydrate methanol.
Thermochimica Acta, 1985
The effect of monovalent ions on the decomposition stages of ammonium metavanadate was studied us... more The effect of monovalent ions on the decomposition stages of ammonium metavanadate was studied using TG and electrical conductivity measurements. It has been determined that Li+ ions affect the decomposition process in a different manner from Na+ or K+ ions. The mechanism by which these ions affect the decomposition process is discussed in relation to the defect structure created by the doping process. EXPERIMENTAL
Thermochimica Acta, 1988
... 126 (1988) 17-24 17 Elsevier Science Publishers BV, Amsterdam - Printed in The Netherlands TH... more ... 126 (1988) 17-24 17 Elsevier Science Publishers BV, Amsterdam - Printed in The Netherlands THERMAL DECOMPOSITION OF KCIQ, CATALYZED BY MnO^-CuO MIXED OXIDES SYSTEMS AM EL-AWAD *, AA SAID ... 9 AA Said, EA Hassan and KM Abd El-Salaam, Surf. ...
Thermochimica Acta, 1985
ABSTRACT The enhancing influence of chromium oxide as a catalyst for the decomposition of KMnO4 h... more ABSTRACT The enhancing influence of chromium oxide as a catalyst for the decomposition of KMnO4 has been studied. Its action was attributed to the presence of surface holes in accepting the released electrons from the intermediate step. There is an indication that a solid-state interaction occurs between the catalyst and the products of decomposition. The reaction products were identified using IR spectroscopy. The inhibition of either Zr4+ or U6+ cations is attributed to the doping effect via the consumption of surface as well as bulk holes.
Monatshefte f�r Chemie / Chemical Monthly, 2004
A series of AlPO 4-V 2 O 5 (APV) systems with various vanadia amounts 1-30 mol% were prepared by ... more A series of AlPO 4-V 2 O 5 (APV) systems with various vanadia amounts 1-30 mol% were prepared by the impregnation method and calcinated at 400 and 600 C for 4 h. The catalysts were characterized by TG=DTG, DSC, IR spectroscopy, XRD, N 2 adsorption, and electrical conductivity measurements. The surface acidity and basicity of the catalysts were studied by the dehydrationdehydrogenation of isopropyl alcohol and the adsorption of pyridine. The catalytic gas phase esterification of acetic acid with ethyl alcohol was carried out at 210 C in a flow system at 1 atm using air as a carrier gas. The results showed that the catalysts calcinated at 400 C were active and selective towards the formation of ethyl acetate whereas the calcination of samples at 600 C led to a drastic reduction in both activity and selectivity. Good correlations were obtained between catalytic activities towards ester formation and acidity of the prepared catalysts.
Journal of Thermal Analysis, 1993
Thermal decomposition of pure Fe(OH)3 and mixed with Co(OH)2 were studied using TG, DTA, kinetics... more Thermal decomposition of pure Fe(OH)3 and mixed with Co(OH)2 were studied using TG, DTA, kinetics of isothermal decomposition and electrical conductivity measurements. The thermal products were characterized by X-ray diffraction and IR spectroscopy. The TG and DTA analysis revealed the presence of Co 2+ retards the decomposition of ferric hydroxide and the formation of 0~-Fe203. The kinetics of decomposition showed that the mixed samples need higher energy to achieve thermolysis. The investigation of thermal products of mixed samples indicated the formation of cobalt ferrite on addition of x = 1 or 1.5 cobalt hydroxide. The electrical conductivity accompanying the thermal decomposition decreases in presence of low ratio of Co z+ (x = 0.2) via the consumption of holes created during thermal analysis. The continuous increase in t~ values on in-. 2+ 9 9 2+ 3+ creasing of Co concentration corresponded to the electron hopping between Fe and Co .
Journal of Thermal Analysis, 1990
Thermal decomposition of pure basic zinc carbonate (BZC) and doped or mixed with iron ions were s... more Thermal decomposition of pure basic zinc carbonate (BZC) and doped or mixed with iron ions were studied using TG, DTA and kinetics of isothermal decomposition. The TG and DTA investigations revealed that, the presence of iron ions retards the decomposition processes of (BZC). Also, the retardation effect increases on increasing of iron concentration up to 50 at.%. The curves of
Journal of Chemical Technology & Biotechnology, 2003
... Correspondence: Abd El-Aziz A Said, Chemistry Department, Faculty of Science, Assiut Universi... more ... Correspondence: Abd El-Aziz A Said, Chemistry Department, Faculty of Science, Assiut University, Assiut, Egypt. Publication History. ... 11 Said AA and Khalil KMS, Catalytic decomposition of ethanol on V 2 O 5 AlPO 4 catalysts. J Chem Technol Biotechnol 75: 19 (2000). ...
Journal of Chemical Technology AND Biotechnology, 1995
Page 1. J. Chem. Tech. Biotechnol. 1995,63,78-84 Oxidative Dehydrogenation of Ethyl Alcohol over ... more Page 1. J. Chem. Tech. Biotechnol. 1995,63,78-84 Oxidative Dehydrogenation of Ethyl Alcohol over Vanadium Pentoxide Supported on Magnesia Abd El-Aziz A. Said* & Mohamed M. M. Abd El-Wahab Chemistry Department, Faculty of Science, Assiut University, Assiut, Egypt ...
Journal of Chemical Technology & Biotechnology, 2006
A series of MoO 3 /SiO 2 catalysts was prepared by an impregnation method with Mo loadings rangin... more A series of MoO 3 /SiO 2 catalysts was prepared by an impregnation method with Mo loadings ranging from 1 to 50 wt%. The original and calcined samples at 400 • C were characterized by thermogravimetry (TG), differential thermogravimetry (DTG), differential scanning calorimetry (DSC), X-ray diffraction (XRD), Fourier transform infra-red (FTIR) spectroscopy, and nitrogen adsorption measurements. The surface acidity and basicity of the catalysts were investigated by the dehydration-dehydrogenation of isopropanol and the chemisorption of pyridine. The catalytic esterification of acetic acid with ethanol was carried out at 220 • C in a conventional fixed-bed reactor at 1 atm using air as a carrier gas. The results clearly revealed that silica-molybdena catalysts were active and selective towards the formation of ethyl acetate. Moreover, the catalyst containing 20 wt% MoO 3 was the most active and selective one. The results emphasize the importance of the surface acid sites together with the specific surface area of the prepared catalyst, towards ester formation.