Muzaffer Yasar - Academia.edu (original) (raw)

Papers by Muzaffer Yasar

Journal of Advanced Research in Natural and Applied Sciences, 2021

In this study, effective and easily accessible cheap catalysts that assist converting heavy oil r... more In this study, effective and easily accessible cheap catalysts that assist converting heavy oil residue to lighter products with high yield are investigated. Hydrocracking experiments were carried out in a 10 ml stainless steel bomb-type reactor with up and down stirrer at 200 times of reciprocation per minute. The catalyst mixture provided the minimum coke yield was investigated. FeSO4.H2O, the binary mixtures of FeSO4.H2O with metal oxides (Fe2O3, Al2O3, CaO, SiO2) and the mixtures Fe2O3, Al2O3 and SiO2 with elementary sulphur were used as catalyst. Experiments were conducted at 425 0C for 90 minutes with the initial pressure 100 bar H2. The amount of coke, liquid products and C5- gas products were calculated for each experiment. Gel Permeation Chromatography (GPC), Nuclear Magnetic Resonance (1H NMR) and elemental analysis were used for Iranian heavy oil residue. Differential Scanning Calorimeter (DSC) was used to analyze the catalyst. According to the results, minimum coke yield...

Journal of Petroleum Science and Engineering, 2020

Arabian Journal for Science and Engineering

In the asphalt pavements, which are prepared by mixing bitumen and aggregates, fatigue cracking a... more In the asphalt pavements, which are prepared by mixing bitumen and aggregates, fatigue cracking and thermal cracking failure occur due to continuous loading and climate conditions. Extending the life of asphalt pavements is very important from an environmental and economic point of view. In this study, reactions are conducted to investigate the effects of six ionic liquids (IL) with different side-chain lengths on the self-healing properties of bitumen. Thermogravimetric analysis and differential scanning calorimetry analysis are performed for ionic liquid characterization, while for bitumen characterization, Saturates, Aromatics, Resins, Asphaltenes (SARA) fractionation of bitumen and Gel Permeation Chromatography, Nuclear Magnetic Resonance, Elemental Analysis of these sub-fractions were performed. In addition, two new test methods have been developed to measure the self-healing capacity of bitumen. The first method shows the effects of rest times when intermittent loading is applied to the sample at high temperatures, while the other method was developed to demonstrate the self-healing ability of bitumen at low temperatures with long rest periods. Stripping tests, asphalt fatigue tests and zeta potential measurements are done to investigate the effects of ionic liquids on bitumen and aggregate interactions. The results indicated that different ionic liquids have different effects on asphalt self-healing mechanism. IL improved the self-healing performance of asphalt 40% at high temperatures, and 100% at low temperature while stripping properties 25% and asphalt fatigue life 20% improved. Therefore, it can be concluded that different bitumen-IL modification recipes could be used for self-healing of asphalt pavements, depending on climatic conditions and traffic density.

International Journal of Hydrogen Energy

International Journal of Hydrogen Energy

Fuel Science and Technology International, 1992

Hondo and Maya vacuum resids and their isolated asphaltenes were pyrolyzed at 400, 425, and 450C ... more Hondo and Maya vacuum resids and their isolated asphaltenes were pyrolyzed at 400, 425, and 450C (752, 797, 842F) for batch holding limes ranging from 20 to 180 minutes. Maltene, asphaltene, and coke product fractions were isolated by a solvent extraction sequence; gas yield was determined gravimetrically. Results were summarized in terms of a lumped reaction network. The variation of product yields, kinetics, and apparent activation energies with feedstock and asphaltene environment provided insight into asphaltene structure and thermal reaction pathways.

Journal of Materials Science, 2007

... Albayrak AT, Yasar M, Gurkaynak MA, Gurgey I (2005) Cem Concr Res 35(2):400 11. ASTM C 430-96... more ... Albayrak AT, Yasar M, Gurkaynak MA, Gurgey I (2005) Cem Concr Res 35(2):400 11. ASTM C 430-96, Standard Test Method for Fineness of Hydraulic Cement by the 45-μm (No.325) Sieve 12. ASTM C 188-95, Standard Test Method for Density of Hydraulic Cement 13. ...

Journal of Analytical and Applied Pyrolysis, 2012

Asphaltenes were precipitated from Raman heavy crude oil subjected to pyrolysis at temperatures o... more Asphaltenes were precipitated from Raman heavy crude oil subjected to pyrolysis at temperatures of 350, 400 and 450 • C for holding times ranging from 10 to 120 min using sandbath. Product fractions were separated as gas, maltene, remaining asphaltene and coke. The time and temperature dependence of product distributions were determined. Molecular structure of remaining asphaltenes was characterized by elemental analysis, Proton Nuclear Magnetic Resonance (1 H NMR), Gel Permeation Chromatography (GPC). These data provide insights into the distribution of heteroatoms and the aromaticity within both original and remaining asphaltenes as well as to the coke formation reactions occurring during the asphaltene pyrolysis. The temporal structural variations of remaining asphaltene allowed discernment of asphaltene thermal pathways.

International Journal of Chemical Reactor Engineering, 2013

The selective oxidation of ammonia to hydroxylamine using titanium silicalite-1 as a catalyst wit... more The selective oxidation of ammonia to hydroxylamine using titanium silicalite-1 as a catalyst with an increasing content range of 1–2.5 wt% TiO2 was systematically investigated in a batch reactor. The hydroxylamine yielded 33, 43, 52 and 62% at reaction temperatures of 50, 60, 70 and 80°C, respectively, for 8 min using a TS-1a catalyst, which contained 2.5% TiO2. The molar ratio of 15 NH3/H2O2 was kept during these reactions. Experiments were also conducted with different amounts of NH3/H2O2 in molar ratios, which were between 7 and 60 to investigate the effect of NH3/H2O2 molar ratio on the reactions. Reactions with higher ratios of NH3/H2O2 were seen to have a higher yield at the end of the reaction performance time.

Fuel, 2007

Adams (2017): Investigation of the glass transition temperature and damping of an acrylic/epoxy b... more Adams (2017): Investigation of the glass transition temperature and damping of an acrylic/epoxy bonding tape using the peak damping method, The Journal of Adhesion,

European Journal of Medicinal Chemistry, 2011

The polyester- and poly(ester-carbonate)-paclitaxel conjugates with low molecular weight were syn... more The polyester- and poly(ester-carbonate)-paclitaxel conjugates with low molecular weight were synthesized using dicyclohexylcarbodiimide (DCC) and dimethylaminopyridine (DMAP) as catalysts. Polymeric matrices were obtained by ring-opening polymerization of ɛ-caprolactone (CL), rac-lactide (rac-LA), l-lactide (LLA) and trimethylene carbonate (TMC). The macromolecular conjugates were characterized by using spectroscopic techniques, such as 1H, 13C NMR and FTIR. The degree of degradation of polyester- and

Energy & Fuels, 1994

A novel probabilistic method for the representation of the molecular components of heavy resid fe... more A novel probabilistic method for the representation of the molecular components of heavy resid feedstocks is introduced. The method describes resid molecule "attributes" in terms of quantitative probability density functions, optimized by comparison of the properties of Monte Carlo-constructed molecules with experimental measurements. Both molecular distributions and averages are provided.

Energy & Fuels, 2001

Pyrolysis experiments with resids and isolated asphaltenes from Arabian Light and Arabian Heavy f... more Pyrolysis experiments with resids and isolated asphaltenes from Arabian Light and Arabian Heavy feedstocks were compared with previous experiments with Hondo and Maya feeds to determine the effect of reaction environment on reaction paths, kinetics, and mechanisms. The experiments were at temperatures of 400, 425, and 450°C for holding times ranging from 20 to 180 min in microbatch reactors. Reaction products were recovered as gas, maltene, asphaltene, and coke lumps. The maltene, asphaltene, and coke product fractions were collected by a solvent extraction sequence where heptane-soluble material was defined as maltene, toluene-soluble material as asphaltene, and toluene-insoluble material as coke. Gas chromatography revealed the presence of C 1-C 5 paraffins, C 2-C 5 olefins, isoparaffins, H 2 S, and CO 2. Results were summarized by a lumped reaction network that allowed for quantitative kinetics analysis. Comparison of relative kinetics and apparent activation energies yielded insight into thermal reaction pathways, feedstock effects, and asphaltene environment effects. At 400 and 425°C, isolated asphaltene reacted selectively to maltene. At 450°C, asphaltene reacted predominately to coke. Isolated maltene pyrolysis indicated that asphaltene and coke formed in series, i.e., maltene f asphaltene f coke.

Cement and Concrete Research, 2005

In cement industry, a great energy consumption has been observed during grinding of clinker. To r... more In cement industry, a great energy consumption has been observed during grinding of clinker. To reduce this consumption, some waste products have been used as grinding aids. In this investigation, the effects of sunflower oil (SO), oleic acid (OA), stearic acid (SA), myristic acid (MA) and lauric acid (LA) on the fineness and strength of the cement have been examined. These aids were added into clinker in certain ratios based on the cement clinker weight and the grinding has been done for a definite time at the same condition. All of the fatty acids used increased the fineness as compared with the cement without the grinding additives. SO and OA decreased the strength significantly, LA decreased it to a lesser extent and SA increased it definitely according to the common cement. But MA did not alter the strength of the cement as much as SA. In addition, the covering of the balls influences the grinding of cement clinker unfavourably.

Energy & Fuels, 1994

The optimal usage of CPU resource for the optimization of resid attribute probability density fun... more The optimal usage of CPU resource for the optimization of resid attribute probability density functions was examined. Alternative strategies involving the use of reaction simulation and data, NMR and increased sample size were examined. The present results suggest optimization with NMR data, large molecular sample sizes, and the absence of reaction simulation as the most efficient strategy.

Journal of Advanced Research in Natural and Applied Sciences, 2021

In this study, effective and easily accessible cheap catalysts that assist converting heavy oil r... more In this study, effective and easily accessible cheap catalysts that assist converting heavy oil residue to lighter products with high yield are investigated. Hydrocracking experiments were carried out in a 10 ml stainless steel bomb-type reactor with up and down stirrer at 200 times of reciprocation per minute. The catalyst mixture provided the minimum coke yield was investigated. FeSO4.H2O, the binary mixtures of FeSO4.H2O with metal oxides (Fe2O3, Al2O3, CaO, SiO2) and the mixtures Fe2O3, Al2O3 and SiO2 with elementary sulphur were used as catalyst. Experiments were conducted at 425 0C for 90 minutes with the initial pressure 100 bar H2. The amount of coke, liquid products and C5- gas products were calculated for each experiment. Gel Permeation Chromatography (GPC), Nuclear Magnetic Resonance (1H NMR) and elemental analysis were used for Iranian heavy oil residue. Differential Scanning Calorimeter (DSC) was used to analyze the catalyst. According to the results, minimum coke yield...

Journal of Petroleum Science and Engineering, 2020

Arabian Journal for Science and Engineering

In the asphalt pavements, which are prepared by mixing bitumen and aggregates, fatigue cracking a... more In the asphalt pavements, which are prepared by mixing bitumen and aggregates, fatigue cracking and thermal cracking failure occur due to continuous loading and climate conditions. Extending the life of asphalt pavements is very important from an environmental and economic point of view. In this study, reactions are conducted to investigate the effects of six ionic liquids (IL) with different side-chain lengths on the self-healing properties of bitumen. Thermogravimetric analysis and differential scanning calorimetry analysis are performed for ionic liquid characterization, while for bitumen characterization, Saturates, Aromatics, Resins, Asphaltenes (SARA) fractionation of bitumen and Gel Permeation Chromatography, Nuclear Magnetic Resonance, Elemental Analysis of these sub-fractions were performed. In addition, two new test methods have been developed to measure the self-healing capacity of bitumen. The first method shows the effects of rest times when intermittent loading is applied to the sample at high temperatures, while the other method was developed to demonstrate the self-healing ability of bitumen at low temperatures with long rest periods. Stripping tests, asphalt fatigue tests and zeta potential measurements are done to investigate the effects of ionic liquids on bitumen and aggregate interactions. The results indicated that different ionic liquids have different effects on asphalt self-healing mechanism. IL improved the self-healing performance of asphalt 40% at high temperatures, and 100% at low temperature while stripping properties 25% and asphalt fatigue life 20% improved. Therefore, it can be concluded that different bitumen-IL modification recipes could be used for self-healing of asphalt pavements, depending on climatic conditions and traffic density.

International Journal of Hydrogen Energy

International Journal of Hydrogen Energy

Fuel Science and Technology International, 1992

Hondo and Maya vacuum resids and their isolated asphaltenes were pyrolyzed at 400, 425, and 450C ... more Hondo and Maya vacuum resids and their isolated asphaltenes were pyrolyzed at 400, 425, and 450C (752, 797, 842F) for batch holding limes ranging from 20 to 180 minutes. Maltene, asphaltene, and coke product fractions were isolated by a solvent extraction sequence; gas yield was determined gravimetrically. Results were summarized in terms of a lumped reaction network. The variation of product yields, kinetics, and apparent activation energies with feedstock and asphaltene environment provided insight into asphaltene structure and thermal reaction pathways.

Journal of Materials Science, 2007

... Albayrak AT, Yasar M, Gurkaynak MA, Gurgey I (2005) Cem Concr Res 35(2):400 11. ASTM C 430-96... more ... Albayrak AT, Yasar M, Gurkaynak MA, Gurgey I (2005) Cem Concr Res 35(2):400 11. ASTM C 430-96, Standard Test Method for Fineness of Hydraulic Cement by the 45-μm (No.325) Sieve 12. ASTM C 188-95, Standard Test Method for Density of Hydraulic Cement 13. ...

Journal of Analytical and Applied Pyrolysis, 2012

Asphaltenes were precipitated from Raman heavy crude oil subjected to pyrolysis at temperatures o... more Asphaltenes were precipitated from Raman heavy crude oil subjected to pyrolysis at temperatures of 350, 400 and 450 • C for holding times ranging from 10 to 120 min using sandbath. Product fractions were separated as gas, maltene, remaining asphaltene and coke. The time and temperature dependence of product distributions were determined. Molecular structure of remaining asphaltenes was characterized by elemental analysis, Proton Nuclear Magnetic Resonance (1 H NMR), Gel Permeation Chromatography (GPC). These data provide insights into the distribution of heteroatoms and the aromaticity within both original and remaining asphaltenes as well as to the coke formation reactions occurring during the asphaltene pyrolysis. The temporal structural variations of remaining asphaltene allowed discernment of asphaltene thermal pathways.

International Journal of Chemical Reactor Engineering, 2013

The selective oxidation of ammonia to hydroxylamine using titanium silicalite-1 as a catalyst wit... more The selective oxidation of ammonia to hydroxylamine using titanium silicalite-1 as a catalyst with an increasing content range of 1–2.5 wt% TiO2 was systematically investigated in a batch reactor. The hydroxylamine yielded 33, 43, 52 and 62% at reaction temperatures of 50, 60, 70 and 80°C, respectively, for 8 min using a TS-1a catalyst, which contained 2.5% TiO2. The molar ratio of 15 NH3/H2O2 was kept during these reactions. Experiments were also conducted with different amounts of NH3/H2O2 in molar ratios, which were between 7 and 60 to investigate the effect of NH3/H2O2 molar ratio on the reactions. Reactions with higher ratios of NH3/H2O2 were seen to have a higher yield at the end of the reaction performance time.

Fuel, 2007

Adams (2017): Investigation of the glass transition temperature and damping of an acrylic/epoxy b... more Adams (2017): Investigation of the glass transition temperature and damping of an acrylic/epoxy bonding tape using the peak damping method, The Journal of Adhesion,

European Journal of Medicinal Chemistry, 2011

The polyester- and poly(ester-carbonate)-paclitaxel conjugates with low molecular weight were syn... more The polyester- and poly(ester-carbonate)-paclitaxel conjugates with low molecular weight were synthesized using dicyclohexylcarbodiimide (DCC) and dimethylaminopyridine (DMAP) as catalysts. Polymeric matrices were obtained by ring-opening polymerization of ɛ-caprolactone (CL), rac-lactide (rac-LA), l-lactide (LLA) and trimethylene carbonate (TMC). The macromolecular conjugates were characterized by using spectroscopic techniques, such as 1H, 13C NMR and FTIR. The degree of degradation of polyester- and

Energy & Fuels, 1994

A novel probabilistic method for the representation of the molecular components of heavy resid fe... more A novel probabilistic method for the representation of the molecular components of heavy resid feedstocks is introduced. The method describes resid molecule "attributes" in terms of quantitative probability density functions, optimized by comparison of the properties of Monte Carlo-constructed molecules with experimental measurements. Both molecular distributions and averages are provided.

Energy & Fuels, 2001

Pyrolysis experiments with resids and isolated asphaltenes from Arabian Light and Arabian Heavy f... more Pyrolysis experiments with resids and isolated asphaltenes from Arabian Light and Arabian Heavy feedstocks were compared with previous experiments with Hondo and Maya feeds to determine the effect of reaction environment on reaction paths, kinetics, and mechanisms. The experiments were at temperatures of 400, 425, and 450°C for holding times ranging from 20 to 180 min in microbatch reactors. Reaction products were recovered as gas, maltene, asphaltene, and coke lumps. The maltene, asphaltene, and coke product fractions were collected by a solvent extraction sequence where heptane-soluble material was defined as maltene, toluene-soluble material as asphaltene, and toluene-insoluble material as coke. Gas chromatography revealed the presence of C 1-C 5 paraffins, C 2-C 5 olefins, isoparaffins, H 2 S, and CO 2. Results were summarized by a lumped reaction network that allowed for quantitative kinetics analysis. Comparison of relative kinetics and apparent activation energies yielded insight into thermal reaction pathways, feedstock effects, and asphaltene environment effects. At 400 and 425°C, isolated asphaltene reacted selectively to maltene. At 450°C, asphaltene reacted predominately to coke. Isolated maltene pyrolysis indicated that asphaltene and coke formed in series, i.e., maltene f asphaltene f coke.

Cement and Concrete Research, 2005

In cement industry, a great energy consumption has been observed during grinding of clinker. To r... more In cement industry, a great energy consumption has been observed during grinding of clinker. To reduce this consumption, some waste products have been used as grinding aids. In this investigation, the effects of sunflower oil (SO), oleic acid (OA), stearic acid (SA), myristic acid (MA) and lauric acid (LA) on the fineness and strength of the cement have been examined. These aids were added into clinker in certain ratios based on the cement clinker weight and the grinding has been done for a definite time at the same condition. All of the fatty acids used increased the fineness as compared with the cement without the grinding additives. SO and OA decreased the strength significantly, LA decreased it to a lesser extent and SA increased it definitely according to the common cement. But MA did not alter the strength of the cement as much as SA. In addition, the covering of the balls influences the grinding of cement clinker unfavourably.

Energy & Fuels, 1994

The optimal usage of CPU resource for the optimization of resid attribute probability density fun... more The optimal usage of CPU resource for the optimization of resid attribute probability density functions was examined. Alternative strategies involving the use of reaction simulation and data, NMR and increased sample size were examined. The present results suggest optimization with NMR data, large molecular sample sizes, and the absence of reaction simulation as the most efficient strategy.