Dimethyl ether (DME) is considered as a highly promising environmentally clean diesel fuel altern... more Dimethyl ether (DME) is considered as a highly promising environmentally clean diesel fuel alternate, which can be produced from synthesis gas. It has high cetane number (55-60) and clean burning properties [1]. Possibility of using CO2 as the carbon source in DME production makes this process even more attractive as a carbon neutral technology. Production of DME from synthesis gas requires a bifunctional catalyst combination, for methanol synthesis and dehydration functions. As for the methanol synthesis function, commercial Cu-ZnO based catalysts are available. Heteropolyacids with very high Bronsted acidity are considered as highly promising catalytic materials for dehydration of methanol to DME [2, 3]. However, they have very low surface area [3]. In the present study, tungstophosphoric acid incorporated mesoporous alumina catalysts with high surface area and ordered pore structures were synthesized, to be used as the methanol dehydration catalysts in DME synthesis. Mesoporous a...
Tablo 1.DME'in fiziksel ve termofiziksel özelliklerinin diğer yakıtlar ile karşılaştırılması …………... more Tablo 1.DME'in fiziksel ve termofiziksel özelliklerinin diğer yakıtlar ile karşılaştırılması …………………………………………………………………….
In the present study, Ni-containing mesoporous aluminosilicate (Al2(SiO2)3) supported catalysts, ... more In the present study, Ni-containing mesoporous aluminosilicate (Al2(SiO2)3) supported catalysts, which are resistant to carbon formation, were developed for hydrogen production from acetic acid. Commercial aluminosilicate (Al2(SiO2)3) was used as catalyst support. Furthermore, to improve the catalyst stability, Mg, La, Ce, Ca, Ru metals, and Ni (5% by mass) were incorporated by the wet impregnation method into the catalyst supports’ structure. The synthesized catalysts were characterized to define their physical and chemical properties. N2 adsorption-desorption results reveal that the resulting isotherm behavior of all the prepared catalysts is consistent with type IV isotherm with plate-like wall structures. The catalytic activity test of the prepared catalysts was investigated at a reaction temperature of 750 C and a feed molar ratio of 1/2.5 (AA/H2O) in a packed bed continuous reactor system. Activity test results showed that catalyst composition has profound effects on product d...
This work investigates the liquid‐phase adsorption of n‐butanol on Amberlyst™15 in the temperatur... more This work investigates the liquid‐phase adsorption of n‐butanol on Amberlyst™15 in the temperature range 295–323 K at different initial adsorbate concentrations. The adsorbent was characterized by N2 physisorption, Fourier transform infrared adsorption of pyridine, scanning electron microscopy, and powder X‐ray diffraction. The data obtained confirmed an adsorbent structure with two porosity levels and amorphous polymer structure. The active sites in Amberlyst™15 are of Brønsted or Brønsted‐Lewis type. The liquid‐phase adsorption equilibrium constants were determined at different temperatures from slurry adsorber experiments. The thermodynamic state functions were estimated and are consistent thermodynamically with physical adsorption. The macropore diffusion coefficients of n‐butanol on Amberlyst™15 were estimated by using the moment technique, and the contribution of surface diffusion to the macropore diffusion coefficients was evaluated.
Core-shell-type catalysts, which are synthesized by encapsulating the Cu-ZnO-Alumina type methano... more Core-shell-type catalysts, which are synthesized by encapsulating the Cu-ZnO-Alumina type methanol synthesis catalyst (CZA) by silicotungstic acid (STA)-incorporated mesoporous alumina, were prepared following a hydrothermal route and tested in DME synthesis from syngas and CO2. Activity tests, which were performed in the pressure range of 30–50 bar, and the temperature range of 200–300 °C, with different feed compositions (CO2/CO/H2: 50/-/50, 40/10/50, 25/25/50, 10/40/50) showed that the best-operating conditions for the highest DME yield were 275 °C and 50 bar. Results proved that the presence of CO2 in the syngas had a positive effect on the DME yield. The total conversion of CO + CO2 increased with an increase in CO2/CO ratio. An overall conversion of CO + CO2 and DME selectivity values were obtained as 65.6% and 73.2%, respectively, with a feed composition of H2/CO2/CO = 50/40/10. Synthesis of methanol using the CZA catalyst from the CO2-containing gas mixtures was also investi...
Biodiesel is an alternative fuel to gasoline due to its environmental and economical benefits. Gl... more Biodiesel is an alternative fuel to gasoline due to its environmental and economical benefits. Glycerol is the main by-product of the biodiesel production by transesterification of vegetable oil with methanol or ethanol. The esterification of glycerol with acetic acid can be a good choice for utilization of by-product glycerol. In this work esterification of glycerol with acetic acid was performed in liquid phase autoclave batch reactor in the presence of Smopex-101. Complete glycerol conversion was achieved in the reaction studies even at room temperatures. Effects of reaction temperatures and initial reactant molar ratios on the glycerol conversions and product selectivity were also investigated. The maximum diacetin (77 %) and triacetin (23 %) selectivities were achieved at 363 K and glycerol/acetic acid; 1/12 molar ratio. Acetylation reactions were performed with acetyl chloride in the presence of Smopex-101 in order to increase triacetin selectivity. 66 % triacetin selectivity ...
Pd/TiO2 catalysts doped with Cu were studied in the reduction of NO with CH4. Temperature program... more Pd/TiO2 catalysts doped with Cu were studied in the reduction of NO with CH4. Temperature programmed desorption of NO was examined, as was the formation of surface species under reactant flows through in-situ diffuse reflectance infrared Fourier transform spectroscopy. These results are then correlated to observed activity for the NO reduction reaction. Over active 1%Cu/2%Pd/TiO2 and 1%Cu/1%Gd/1%Pd/TiO2 significantly more NO adsorption and NO2 formation were observed than over the inactive 2%Cu/2%Pd/TiO2 catalyst. Additionally, the formation of the active surface species Pd-NO and surface NH3 groups was seen only over the active formulations. Cu loading plays an important role in determining the reduction activity of the studied catalyst, apparently through significantly modifying the adsorption characteristics and surface reactions of the Pd/TiO2 catalysts.
Abstract In the present study, a set of methanol synthesis catalysts with different Cu/Zn/Al or C... more Abstract In the present study, a set of methanol synthesis catalysts with different Cu/Zn/Al or Cu/Zn/Zr molar ratios were synthesized by a co-precipitation method. Silicotungstic acid and tungstophosphoric acid were impregnated into these materials to synthesize new bifunctional catalytic materials to be used in direct synthesis of dimethyl ether (DME) from syngas. In the case of methanol production, synthesized Cu/Zn/Al catalysts exhibited quite high methanol selectivity, reaching to approximately 87%. These results indicated that the dispersion of copper particles profoundly affected the selectivity of methanol. Direct synthesis of DME was investigated in the presence of heteropoly acid impregnated copper-based novel hybrid type bifunctional catalysts. Results revealed that product distributions were strongly influenced by the reaction temperature, pressure, heteropoly acid content, and type. Results proved that silicotungstic acid (STA) impregnated bifunctional catalysts showed much better catalytic performance than the tungstophosphoric acid (TPA) impregnated ones in DME synthesis from syngas. Very high dimethyl ether selectivity values were achieved in direct synthesis of dimethyl ether over the 25%, and 30% STA impregnated methanol synthesis catalysts, at 275 °C and 50 bar. DME selectivity presented an increasing trend due to the increase in heteropoly acid content over methanol synthesis catalysts. The silicotungstic acid incorporated (30%) Cu/Zn/Al catalyst, having a composition of 6/3/1 (30STA@CZA:631), showed the highest CO conversion and DME selectivity. However, coke formation over this catalyst was much more than the catalyst containing 25% STA. This is mainly due to the higher Bronsted acidity of 30STA@CZA:631 than 25STA@CZA:631. Low coke formation, together with quite high DME selectivity values achieved with 25STA@CZA:631, is a worthy distinction of this catalyst for the direct synthesis of DME from synthesis gas. Graphic Abstract Novel hybrid type catalysts are successfully synthesized for direct synthesis of dimethyl ether process. Heteropoly acid incorporated methanol synthesis catalysts are very active and stable in the direct synthesis of dimethyl ether process. Silicotungstic acid (STA) impregnated copper-based catalyst exhibits a superior performance than the tungstophosphoric acid impregnated catalyst.
A series of active and selective MCM-41 supported catalysts have been successfully prepared and u... more A series of active and selective MCM-41 supported catalysts have been successfully prepared and used for bioderived glycerol esterification with acetic acid to produce fuel additives. In the synthesis of MCM-41, an acidic hydrothermal synthesis route was used, and silicotungstic acid (STA) and zirconia (ZrO2) were added to the catalyst structure by wet impregnation. X-ray diffraction, nitrogen adsorption-desorption methods, scanning electron microscopy with energy-dispersive spectroscopy, and inductively coupled plasma-mass spectrometry analysis were used for characterizations of the catalysts. Diffuse reflectance infrared Fourier transform spectroscopy analyses of pyridine-adsorbed catalysts owns Lewis and Brønsted acidity hosting in one, which promotes the esterification reaction of glycerol into glycerol esters with high selectivity. Esterification of glycerol reactions were performed at temperature intervals of 105°C–200°C, with an amount of catalyst equal to 0.5 g, and glycerol...
Abstract Steam reforming of acetic acid (AcOH) was investigated over mesoporous alumina supported... more Abstract Steam reforming of acetic acid (AcOH) was investigated over mesoporous alumina supported mono- and bi-metallic Ni and/or Cu based catalysts. Results obtained with mesoporous alumina supported catalysts were compared with another set of experiments performed using a commercial Cu Zn based HifuelR-120 catalyst and Ni impregnated HifuelR-120. Comparison of catalytic performances of Cu and Ni based catalysts showed that Cu activated the decomposition of AcOH giving mainly CH 4 and CO 2 , while Ni was highly active for steam reforming reaction, yielding quite high H 2 selectivities, reaching to 70%. This H 2 selectivity was quite close to the equilibrium limit. Very low CO selectivity observed with HifuelR-120 and low CO/CO 2 ratios observed especially with the Cu based catalysts clearly indicated that CO was not an intermediate of AcOH reforming reaction, but formed mainly as a result of reverse water gas shift reaction. Ni containing catalysts were shown to have high activity also for the reverse water gas shift reaction. Comparison of the performances of mono-metallic Ni and bi-metallic Ni Cu containing MA catalysts showed that the performance of the bi-metallic catalyst was better, yielding less CH 4 . Although the activities of nickel containing catalysts were quite high in steam reforming of AcOH, they yield more coke as compared to Cu based materials.
Gazi Üniversitesi Mühendislik-Mimarlık Fakültesi Dergisi, 2015
Çevreci bir yakıt olan biyodizel çeşitli avantajlarından ötürü dizel yakıta alternatif bir yakıtt... more Çevreci bir yakıt olan biyodizel çeşitli avantajlarından ötürü dizel yakıta alternatif bir yakıttır. Bitkisel yağın metanol veya etanol ile transesterleşmesiyle biyodizel üretilmekte ve yan ürün olarak önemli miktarda gliserin oluşmaktadır. Gliserinin asetik asitle esterleşmesi biyodizel üretiminden kaynaklanan artan gliserinin değerlendirilmesi açısından alternatif bir çözüm teşkil eder. Yapılan çalışmada gliserinin asetik asitle esterleşme reaksiyonu Smopex-101 varlığında sıvı faz kesikli otoklav reaktörde incelenmiştir. Yapılan reaksiyon çalışmalarında oda sıcaklığında oldukça kısa sürede (25 dakika) %100 gliserin dönüşümüne ulaşılmıştır. Reaksiyon sıcaklığı ve başlangıç reaktan molar oranlarının gliserin dönüşümü ve ürün seçiciliği açısından etkisi incelenmiştir. En yüksek diasetin (%77) ve triasetin (%23) seçiciliğine 363K'de ve gliserin/asetik asit;1/12 molar oranında ulaşılmıştır. Triasetin seçiciliğini artırmaya yönelik asetil klorür ile Smopex-101 varlığında asetilasyon reaksiyonu gerçekleştirimiştir. Oda sıcaklığında gerçekleştirilen çalışmalarda 1200 dakika sonunda %60 triasetin seçiciliğine ulaşılmıştır.
ABSTRACT In this study, a detailed thermodynamic analysis of the ethyl tert-butyl ether (ETBE) sy... more ABSTRACT In this study, a detailed thermodynamic analysis of the ethyl tert-butyl ether (ETBE) synthesis reaction between tert-butyl alcohol (TBA) and ethanol is performed to determine a liquid phase equilibrium constant expression. The result is of practical significance in view of the imminent prominence of ETBE to be produced from TBA and ethanol, as a gasoline blending oxygenate. In this study, enthalpy of formation, Gibbs, enthalpy of vaporization, and heat capacities (as a function of temperature) of the reactants and products were estimated. At 298 K, the standard molar enthalpy of reaction for ETBE from TBA and ethanol was found as −1.23 kJ·mol−1. The liquid phase nonideality of the system was tested, and it was found that the system approaches ideal conditions. The thermodynamic analysis approach given here is expected to be useful for other liquid-phase systems.
Although WCO plays a crucial role for the economical production of biodiesel, free fatty acid (FF... more Although WCO plays a crucial role for the economical production of biodiesel, free fatty acid (FFA) level in the nature of WCO cause saponification problems during transesterification. Acidic ion-exchange resins can be used to decrease WCO free fatty acid level. In this study, activities of resins (Amberlyst-15 (A-15), Amberlyst-35 (A-35), Amberlyst-16 (A-16) and Dowex HCR-W2) in direct FFA esterification were examined in the temperature range of 50-60°C and the effect of catalyst amount (1-2 wt%) on FFA conversion was also analyzed. FFA conversion increased with increasing reaction temperature and catalyst amount. Order of catalytic activities was found as A-15 > A-35 > A-16 > Dowex HCR-W2. This was related to the size of average pore diameters and magnitude of BET surface area.
Dimethyl ether (DME) is considered as a highly promising environmentally clean diesel fuel altern... more Dimethyl ether (DME) is considered as a highly promising environmentally clean diesel fuel alternate, which can be produced from synthesis gas. It has high cetane number (55-60) and clean burning properties [1]. Possibility of using CO2 as the carbon source in DME production makes this process even more attractive as a carbon neutral technology. Production of DME from synthesis gas requires a bifunctional catalyst combination, for methanol synthesis and dehydration functions. As for the methanol synthesis function, commercial Cu-ZnO based catalysts are available. Heteropolyacids with very high Bronsted acidity are considered as highly promising catalytic materials for dehydration of methanol to DME [2, 3]. However, they have very low surface area [3]. In the present study, tungstophosphoric acid incorporated mesoporous alumina catalysts with high surface area and ordered pore structures were synthesized, to be used as the methanol dehydration catalysts in DME synthesis. Mesoporous a...
Tablo 1.DME'in fiziksel ve termofiziksel özelliklerinin diğer yakıtlar ile karşılaştırılması …………... more Tablo 1.DME'in fiziksel ve termofiziksel özelliklerinin diğer yakıtlar ile karşılaştırılması …………………………………………………………………….
In the present study, Ni-containing mesoporous aluminosilicate (Al2(SiO2)3) supported catalysts, ... more In the present study, Ni-containing mesoporous aluminosilicate (Al2(SiO2)3) supported catalysts, which are resistant to carbon formation, were developed for hydrogen production from acetic acid. Commercial aluminosilicate (Al2(SiO2)3) was used as catalyst support. Furthermore, to improve the catalyst stability, Mg, La, Ce, Ca, Ru metals, and Ni (5% by mass) were incorporated by the wet impregnation method into the catalyst supports’ structure. The synthesized catalysts were characterized to define their physical and chemical properties. N2 adsorption-desorption results reveal that the resulting isotherm behavior of all the prepared catalysts is consistent with type IV isotherm with plate-like wall structures. The catalytic activity test of the prepared catalysts was investigated at a reaction temperature of 750 C and a feed molar ratio of 1/2.5 (AA/H2O) in a packed bed continuous reactor system. Activity test results showed that catalyst composition has profound effects on product d...
This work investigates the liquid‐phase adsorption of n‐butanol on Amberlyst™15 in the temperatur... more This work investigates the liquid‐phase adsorption of n‐butanol on Amberlyst™15 in the temperature range 295–323 K at different initial adsorbate concentrations. The adsorbent was characterized by N2 physisorption, Fourier transform infrared adsorption of pyridine, scanning electron microscopy, and powder X‐ray diffraction. The data obtained confirmed an adsorbent structure with two porosity levels and amorphous polymer structure. The active sites in Amberlyst™15 are of Brønsted or Brønsted‐Lewis type. The liquid‐phase adsorption equilibrium constants were determined at different temperatures from slurry adsorber experiments. The thermodynamic state functions were estimated and are consistent thermodynamically with physical adsorption. The macropore diffusion coefficients of n‐butanol on Amberlyst™15 were estimated by using the moment technique, and the contribution of surface diffusion to the macropore diffusion coefficients was evaluated.
Core-shell-type catalysts, which are synthesized by encapsulating the Cu-ZnO-Alumina type methano... more Core-shell-type catalysts, which are synthesized by encapsulating the Cu-ZnO-Alumina type methanol synthesis catalyst (CZA) by silicotungstic acid (STA)-incorporated mesoporous alumina, were prepared following a hydrothermal route and tested in DME synthesis from syngas and CO2. Activity tests, which were performed in the pressure range of 30–50 bar, and the temperature range of 200–300 °C, with different feed compositions (CO2/CO/H2: 50/-/50, 40/10/50, 25/25/50, 10/40/50) showed that the best-operating conditions for the highest DME yield were 275 °C and 50 bar. Results proved that the presence of CO2 in the syngas had a positive effect on the DME yield. The total conversion of CO + CO2 increased with an increase in CO2/CO ratio. An overall conversion of CO + CO2 and DME selectivity values were obtained as 65.6% and 73.2%, respectively, with a feed composition of H2/CO2/CO = 50/40/10. Synthesis of methanol using the CZA catalyst from the CO2-containing gas mixtures was also investi...
Biodiesel is an alternative fuel to gasoline due to its environmental and economical benefits. Gl... more Biodiesel is an alternative fuel to gasoline due to its environmental and economical benefits. Glycerol is the main by-product of the biodiesel production by transesterification of vegetable oil with methanol or ethanol. The esterification of glycerol with acetic acid can be a good choice for utilization of by-product glycerol. In this work esterification of glycerol with acetic acid was performed in liquid phase autoclave batch reactor in the presence of Smopex-101. Complete glycerol conversion was achieved in the reaction studies even at room temperatures. Effects of reaction temperatures and initial reactant molar ratios on the glycerol conversions and product selectivity were also investigated. The maximum diacetin (77 %) and triacetin (23 %) selectivities were achieved at 363 K and glycerol/acetic acid; 1/12 molar ratio. Acetylation reactions were performed with acetyl chloride in the presence of Smopex-101 in order to increase triacetin selectivity. 66 % triacetin selectivity ...
Pd/TiO2 catalysts doped with Cu were studied in the reduction of NO with CH4. Temperature program... more Pd/TiO2 catalysts doped with Cu were studied in the reduction of NO with CH4. Temperature programmed desorption of NO was examined, as was the formation of surface species under reactant flows through in-situ diffuse reflectance infrared Fourier transform spectroscopy. These results are then correlated to observed activity for the NO reduction reaction. Over active 1%Cu/2%Pd/TiO2 and 1%Cu/1%Gd/1%Pd/TiO2 significantly more NO adsorption and NO2 formation were observed than over the inactive 2%Cu/2%Pd/TiO2 catalyst. Additionally, the formation of the active surface species Pd-NO and surface NH3 groups was seen only over the active formulations. Cu loading plays an important role in determining the reduction activity of the studied catalyst, apparently through significantly modifying the adsorption characteristics and surface reactions of the Pd/TiO2 catalysts.
Abstract In the present study, a set of methanol synthesis catalysts with different Cu/Zn/Al or C... more Abstract In the present study, a set of methanol synthesis catalysts with different Cu/Zn/Al or Cu/Zn/Zr molar ratios were synthesized by a co-precipitation method. Silicotungstic acid and tungstophosphoric acid were impregnated into these materials to synthesize new bifunctional catalytic materials to be used in direct synthesis of dimethyl ether (DME) from syngas. In the case of methanol production, synthesized Cu/Zn/Al catalysts exhibited quite high methanol selectivity, reaching to approximately 87%. These results indicated that the dispersion of copper particles profoundly affected the selectivity of methanol. Direct synthesis of DME was investigated in the presence of heteropoly acid impregnated copper-based novel hybrid type bifunctional catalysts. Results revealed that product distributions were strongly influenced by the reaction temperature, pressure, heteropoly acid content, and type. Results proved that silicotungstic acid (STA) impregnated bifunctional catalysts showed much better catalytic performance than the tungstophosphoric acid (TPA) impregnated ones in DME synthesis from syngas. Very high dimethyl ether selectivity values were achieved in direct synthesis of dimethyl ether over the 25%, and 30% STA impregnated methanol synthesis catalysts, at 275 °C and 50 bar. DME selectivity presented an increasing trend due to the increase in heteropoly acid content over methanol synthesis catalysts. The silicotungstic acid incorporated (30%) Cu/Zn/Al catalyst, having a composition of 6/3/1 (30STA@CZA:631), showed the highest CO conversion and DME selectivity. However, coke formation over this catalyst was much more than the catalyst containing 25% STA. This is mainly due to the higher Bronsted acidity of 30STA@CZA:631 than 25STA@CZA:631. Low coke formation, together with quite high DME selectivity values achieved with 25STA@CZA:631, is a worthy distinction of this catalyst for the direct synthesis of DME from synthesis gas. Graphic Abstract Novel hybrid type catalysts are successfully synthesized for direct synthesis of dimethyl ether process. Heteropoly acid incorporated methanol synthesis catalysts are very active and stable in the direct synthesis of dimethyl ether process. Silicotungstic acid (STA) impregnated copper-based catalyst exhibits a superior performance than the tungstophosphoric acid impregnated catalyst.
A series of active and selective MCM-41 supported catalysts have been successfully prepared and u... more A series of active and selective MCM-41 supported catalysts have been successfully prepared and used for bioderived glycerol esterification with acetic acid to produce fuel additives. In the synthesis of MCM-41, an acidic hydrothermal synthesis route was used, and silicotungstic acid (STA) and zirconia (ZrO2) were added to the catalyst structure by wet impregnation. X-ray diffraction, nitrogen adsorption-desorption methods, scanning electron microscopy with energy-dispersive spectroscopy, and inductively coupled plasma-mass spectrometry analysis were used for characterizations of the catalysts. Diffuse reflectance infrared Fourier transform spectroscopy analyses of pyridine-adsorbed catalysts owns Lewis and Brønsted acidity hosting in one, which promotes the esterification reaction of glycerol into glycerol esters with high selectivity. Esterification of glycerol reactions were performed at temperature intervals of 105°C–200°C, with an amount of catalyst equal to 0.5 g, and glycerol...
Abstract Steam reforming of acetic acid (AcOH) was investigated over mesoporous alumina supported... more Abstract Steam reforming of acetic acid (AcOH) was investigated over mesoporous alumina supported mono- and bi-metallic Ni and/or Cu based catalysts. Results obtained with mesoporous alumina supported catalysts were compared with another set of experiments performed using a commercial Cu Zn based HifuelR-120 catalyst and Ni impregnated HifuelR-120. Comparison of catalytic performances of Cu and Ni based catalysts showed that Cu activated the decomposition of AcOH giving mainly CH 4 and CO 2 , while Ni was highly active for steam reforming reaction, yielding quite high H 2 selectivities, reaching to 70%. This H 2 selectivity was quite close to the equilibrium limit. Very low CO selectivity observed with HifuelR-120 and low CO/CO 2 ratios observed especially with the Cu based catalysts clearly indicated that CO was not an intermediate of AcOH reforming reaction, but formed mainly as a result of reverse water gas shift reaction. Ni containing catalysts were shown to have high activity also for the reverse water gas shift reaction. Comparison of the performances of mono-metallic Ni and bi-metallic Ni Cu containing MA catalysts showed that the performance of the bi-metallic catalyst was better, yielding less CH 4 . Although the activities of nickel containing catalysts were quite high in steam reforming of AcOH, they yield more coke as compared to Cu based materials.
Gazi Üniversitesi Mühendislik-Mimarlık Fakültesi Dergisi, 2015
Çevreci bir yakıt olan biyodizel çeşitli avantajlarından ötürü dizel yakıta alternatif bir yakıtt... more Çevreci bir yakıt olan biyodizel çeşitli avantajlarından ötürü dizel yakıta alternatif bir yakıttır. Bitkisel yağın metanol veya etanol ile transesterleşmesiyle biyodizel üretilmekte ve yan ürün olarak önemli miktarda gliserin oluşmaktadır. Gliserinin asetik asitle esterleşmesi biyodizel üretiminden kaynaklanan artan gliserinin değerlendirilmesi açısından alternatif bir çözüm teşkil eder. Yapılan çalışmada gliserinin asetik asitle esterleşme reaksiyonu Smopex-101 varlığında sıvı faz kesikli otoklav reaktörde incelenmiştir. Yapılan reaksiyon çalışmalarında oda sıcaklığında oldukça kısa sürede (25 dakika) %100 gliserin dönüşümüne ulaşılmıştır. Reaksiyon sıcaklığı ve başlangıç reaktan molar oranlarının gliserin dönüşümü ve ürün seçiciliği açısından etkisi incelenmiştir. En yüksek diasetin (%77) ve triasetin (%23) seçiciliğine 363K'de ve gliserin/asetik asit;1/12 molar oranında ulaşılmıştır. Triasetin seçiciliğini artırmaya yönelik asetil klorür ile Smopex-101 varlığında asetilasyon reaksiyonu gerçekleştirimiştir. Oda sıcaklığında gerçekleştirilen çalışmalarda 1200 dakika sonunda %60 triasetin seçiciliğine ulaşılmıştır.
ABSTRACT In this study, a detailed thermodynamic analysis of the ethyl tert-butyl ether (ETBE) sy... more ABSTRACT In this study, a detailed thermodynamic analysis of the ethyl tert-butyl ether (ETBE) synthesis reaction between tert-butyl alcohol (TBA) and ethanol is performed to determine a liquid phase equilibrium constant expression. The result is of practical significance in view of the imminent prominence of ETBE to be produced from TBA and ethanol, as a gasoline blending oxygenate. In this study, enthalpy of formation, Gibbs, enthalpy of vaporization, and heat capacities (as a function of temperature) of the reactants and products were estimated. At 298 K, the standard molar enthalpy of reaction for ETBE from TBA and ethanol was found as −1.23 kJ·mol−1. The liquid phase nonideality of the system was tested, and it was found that the system approaches ideal conditions. The thermodynamic analysis approach given here is expected to be useful for other liquid-phase systems.
Although WCO plays a crucial role for the economical production of biodiesel, free fatty acid (FF... more Although WCO plays a crucial role for the economical production of biodiesel, free fatty acid (FFA) level in the nature of WCO cause saponification problems during transesterification. Acidic ion-exchange resins can be used to decrease WCO free fatty acid level. In this study, activities of resins (Amberlyst-15 (A-15), Amberlyst-35 (A-35), Amberlyst-16 (A-16) and Dowex HCR-W2) in direct FFA esterification were examined in the temperature range of 50-60°C and the effect of catalyst amount (1-2 wt%) on FFA conversion was also analyzed. FFA conversion increased with increasing reaction temperature and catalyst amount. Order of catalytic activities was found as A-15 > A-35 > A-16 > Dowex HCR-W2. This was related to the size of average pore diameters and magnitude of BET surface area.
Uploads
Papers by Nuray Oktar