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Christos Kordulis - One of the best experts on this subject based on the ideXlab platform.
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w promoted ni al2o3 co precipitated catalysts for Green Diesel production
Fuel Processing Technology, 2021Co-Authors: Christos Papadopoulos, Eleana Kordouli, Kyriakos Bourikas, Christos Kordulis, Labrini Sygellou, Alexis LycourghiotisAbstract:Abstract The promoting action of W in the Ni-Al2O3 co-precipitated catalysts with high nickel loading (31–46 wt% Ni) has been investigated in the selective deoxygenation of sunflower oil and waste cooking oil towards Green Diesel production. A WNi-Al2O3 catalyst containing 8 wt% W and 35 wt% Ni ( Ni Ni + W = 0.9 atomic ratio) proven the most efficient. The detailed characterization of the catalysts allowed an insight concerning the tungsten promoting action. It was attributed to the increase in the catalyst specific surface area and metallic nickel surface area, the acidity regulation, the decrease of the amount of catalytically inactive nickel aluminate formed and to the participation of W5+-oxo species via their defect oxygen sites in the selective deoxygenation network. The optimum reduction – activation temperature was found at 500 °C, where a good compromise between the increase of metallic Ni relative amount, the decrease of the specific surface area and the increase of Ni mean crystal size is achieved.
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Green Diesel production over nickel alumina nanostructured catalysts promoted by zinc
Catalysis Today, 2020Co-Authors: Mantha Gousi, Eleana Kordouli, Kyriakos Bourikas, Christos Kordulis, S Ladas, Emmanouil Simianakis, George D PanagiotouAbstract:Abstract Following the one step co-precipitation technique we have synthesized a series of Ni-Zn catalysts supported on alumina. The series involves one non-promoted sample containing 60 wt % Ni and three zinc promoted samples containing 1, 2 and 5 wt % Zn and 59, 58 and 55 wt % Ni, respectively. The specimens were characterized using nitrogen sorption isotherms, H2-TPR, NH3-TPD, XRD, SEM-EDX, TEM and XPS. The catalytic performance of the samples prepared was evaluated in the selective deoxygenation of sunflower oil using a semi-batch reactor (310 °C, 40 bar of hydrogen, hydrogen flow rate equal to 100 mL/min and reactant to catalyst ratio equal to 100 mL/g). The control of the co-precipitation procedure and the direct reduction of dried precipitate resulted to mesoporous nano-structured catalysts with high surface area (247–290 m2 g−1). The non-promoted sample was mainly comprised from NiAl2O4 particles and the promoted ones from Ni-Zn alloys and intermetallic oxo-phases (IMPs) supported on largely amorphous Al2O3 nano-grains. Zinc increased the total yield of alkanes in the Diesel range (n-15, n-16, n-17, n-18) though it does not affect the mechanistic scheme of the selective deoxygenation of sunflower oil which is largely realized via decarbonylation/decarboxylation. The promoting action of zinc was attributed to the favoring of the Ni-Zn alloys and IMPs formation. It is more pronounced in the sample with the medium zinc content (58 wt % Ni, 2 wt % Zn, 40 wt % Al2O3) in which an increase of 18% in the total yield of hydrocarbons has been obtained. The maximization of the zinc promoting action in this sample reflects the good compromise between the extent of alloying and surface acidity.
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Green Diesel production over nickel alumina nanostructured catalysts promoted by copper
Energies, 2020Co-Authors: Mantha Gousi, Eleana Kordouli, Kyriakos Bourikas, Christos Kordulis, Emmanouil Symianakis, S Ladas, Alexis LycourghiotisAbstract:A series of nickel–alumina catalysts promoted by copper containing 1, 2, and 5 wt. % Cu and 59, 58, and 55 wt. % Ni, respectively, (symbols: 59Ni1CuAl, 58Ni2CuAl, 55Ni5CuAl) and a non-promoted catalyst containing 60 wt. % Ni (symbol: 60NiAl) were prepared following a one-step co-precipitation method. They were characterized using various techniques (N2 sorption isotherms, XRD, SEM-EDX, XPS, H2-TPR, NH3-TPD) and evaluated in the selective deoxygenation of sunflower oil using a semi-batch reactor (310 °C, 40 bar of hydrogen, 96 mL/min hydrogen flow rate, and 100 mL/1 g reactant to catalyst ratio). The severe control of the co-precipitation procedure and the direct reduction (without previous calcination) of precursor samples resulted in mesoporous nano-structured catalysts (most of the pores in the range 3–5 nm) exhibiting a high surface area (192–285 m2 g−1). The promoting action of copper is demonstrated for the first time for catalysts with a very small Cu/Ni weight ratio (0.02–0.09). The effect is more pronounced in the catalyst with the medium copper content (58Ni2CuAl) where a 17.2% increase of Green Diesel content in the liquid products has been achieved with respect to the non-promoted catalyst. The copper promoting action was attributed to the increase in the nickel dispersion as well as to the formation of a Ni-Cu alloy being very rich in nickel. A portion of the Ni-Cu alloy nanoparticles is covered by Ni0 and Cu0 nanoparticles in the 59Ni1CuAl and 55Ni5CuAl catalysts, respectively. The maximum promoting action observed in the 58Ni2CuAl catalyst was attributed to the finding that, in this catalyst, there is no considerable masking of the Ni-Cu alloy by Ni0 or Cu0. The relatively low performance of the 55Ni5CuAl catalyst with respect to the other promoted catalysts was attributed, in addition to the partial coverage of Ni-Cu alloy by Cu0, to the remarkably low weak/moderate acidity and relatively high strong acidity exhibited by this catalyst. The former favors selective deoxygenation whereas the latter favors coke formation. Copper addition does not affect the selective-deoxygenation reactions network, which proceeds predominantly via the dehydration-decarbonylation route over all the catalysts studied.
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waste cooking oil transformation into third generation Green Diesel catalyzed by nickel alumina catalysts
Molecular Catalysis, 2020Co-Authors: Ioannis Nikolopoulos, Eleana Kordouli, Kyriakos Bourikas, Christos Kordulis, George Kogkos, Alexis LycourghiotisAbstract:Abstract Three nickel-alumina catalysts were prepared with nickel content 60, 80 and 90 wt % (symbols: 60NiAl, 80NiAl, 90NiAl) following a co-precipitation methodology. The catalysts were characterized and evaluated in the selective deoxygenation of waste cooking oil for the production of third generation Green Diesel under solvent free conditions. Metallic Ni, NiO, and NiAl2O4 were detected in the 60NiAl catalyst. NiAl2O4 is hardly detected in the 80NiAl catalyst but not at all in the 90NiAl catalyst. The extent of reduction of NiO to metallic Ni upon activation is considerably higher in the 80NiAl and 90NiAl samples with respect to the 60NiAl sample resulting in much higher active site population. The increase in the nickel content causes a change in the porous structure and a decrease in the specific surface area. The catalytic performance increases considerably from the 60NiAl catalyst to the 80NiAl one due to the increase in the active site population. The higher catalytic performance of the 80NiAl catalyst with respect to that of the 90NiAl catalyst, exhibiting almost equal active site population, is due to convenient porous structure of 80NiAl catalyst, which hinder the insertion of deleterious bulky compounds present in the waste cooking oil, as well as to its strong acid sites.
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nickel catalysts supported on palygorskite for transformation of waste cooking oils into Green Diesel
Applied Catalysis B-environmental, 2019Co-Authors: Eleana Kordouli, Kyriakos Bourikas, Christos Kordulis, Sotiris Lycourghiotis, Labrini SygellouAbstract:Abstract Nickel catalysts supported on palygorskite of varying Ni content were synthesized following the deposition–precipitation method. The catalysts were characterized using various techniques and evaluated in a semi-batch reactor for the transformation of waste cooking oils (WCO) into Green Diesel at 310 °C and hydrogen pressure 40 bar. The nickel nanoparticles supported on palygorskite were proved to be very active. The conversion of the WCO was about 100%. The Green Diesel content of the liquid product depends mainly on the nickel surface exposed per gram of catalyst, following a volcano like trend and maximized (81.9 wt %) over the sample with 30 wt % Ni. Taking into account the very high ratio of WCO volume to catalyst mass (100 mL/g) and that the evaluation of the catalysts was performed under solvent free conditions, these results demonstrate the successful use of mineral palygorskite for developing promising “natural catalysts” for Green Diesel production.
Yun Hin Taufiqyap - One of the best experts on this subject based on the ideXlab platform.
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combustion and emission performance of co nox sox for Green Diesel blends in a swirl burner
ACS omega, 2021Co-Authors: Abdulkareem Ghassan Alsultan, Nurul Asikin Mijan, Nasar Mansir, Siti Zulaika Razali, Robiah Yunus, Yun Hin TaufiqyapAbstract:Green Diesel is one of the alternative energy sources, which is found to be a second-generation biofuel. Green Diesel has a similar molecular structure to petroleum Diesel but has better Diesel properties, sustainability, and environmental benignity. In this study, Green Diesel was synthesized from waste cooking oil via a deoxygenation reaction process and blended with petroleum Diesel to assess the rate of Greenhouse gas emissions. The fuel properties of the formed G100 (pure Green Diesel) were investigated, and the performance of G5 and G20 (a mixture of 5 and 20% Green Diesel in petroleum Diesel) was tested for combustion in an oil burner. The overall test showed that the combustion of the blends of Green Diesel produced lower CO2 and SO2 emissions than that of petroleum Diesel as a result of the rich oxygen-free fuel content. The obtained fuel properties of pure Green Diesel and blended Green Diesel are in compliance with ASTM D6751, ASTM D240-17, and EN 14214 standards. Based on these findings, it is shown that blended Green Diesel is a clean fuel for the environment and a promising alternative fuel for internal combustion engines.
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Green Diesel production from palm fatty acid distillate over sba 15 supported nickel cobalt and nickel cobalt catalysts
Biomass & Bioenergy, 2020Co-Authors: Muhammad Fadhli Kamaruzaman, Yun Hin Taufiqyap, Darfizzi DerawiAbstract:Abstract The utilization of non-edible and low-cost feedstock in bioenergy research is getting more attention in recent decades. Catalytic deoxygenation of fatty acids from waste oil feedstocks is a promising route to produce Diesel-like hydrocarbons. Here we report the conversion of palm fatty acid distillate (PFAD), a low-value side product of physical refining of crude palm oil, into Green Diesel using a solventless and hydrogen-free deoxygenation (DO) reaction using catalytic deoxygenation over solid acid catalysts (Co/SBA-15, Ni/SBA-15, and Ni–Co/SBA-15) with total metal loadings of 5 wt%. Metal precursors (Ni, Co, Ni–Co) were doped on the mesostructured catalyst supporter, SBA-15 by wet impregnation. The catalysts were characterized by nitrogen adsorption-desorption isotherm analysis, X-ray diffraction, X-ray fluorescence, infrared spectroscopy, and high-resolution transmission electron microscopy with elemental mapping. The DO reaction was carried out in a semi-batch reactor with a catalyst loading of 10 wt% at 350 °C for 3 h. The use of both Ni/SBA-15 and Ni–Co/SBA-15 afforded products with high contents of liquid hydrocarbons (C8–C17) with yields of 85.8% and 88.1%, respectively, and selectivity for Diesel-range hydrocarbons (C13–C17) above 85% were achieved. Cobalt seems to have a larger particle size, then associates with the carbon formation and introduces coke formation. It blocks some pores and deactivates the active sites of the catalyst, thus reducing the catalytic activity.
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efficient deoxygenation of waste cooking oil over co3o4 la2o3 doped activated carbon for the production of Diesel like fuel
RSC Advances, 2020Co-Authors: Hwei Voon Lee, Yun Hin Taufiqyap, N Asikinmijan, G Abdulkareemalsultan, Karen Wilson, G MustafaalsultanAbstract:Untreated waste cooking oil (WCO) with significant levels of water and fatty acids (FFAs) was deoxygenated over Co3O4–La2O3/ACnano catalysts under an inert flow of N2 in a micro-batch closed system for the production of Green Diesel. The primary reaction mechanism was found to be the decarbonylation/decarboxylation (deCOx) pathway in the Co3O4–La2O3/ACnano-catalyzed reaction. The effect of cobalt doping, catalyst loading, different deoxygenation (DO) systems, temperature and time were investigated. The results indicated that among the various cobalt doping levels (between 5 and 25 wt%), the maximum catalytic activity was exhibited with the Co : La ratio of 20 : 20 wt/wt% DO under N2 flow, which yielded 58% hydrocarbons with majority Diesel-range (n-(C15 + C17)) selectivity (∼63%), using 3 wt% catalyst loading at a temperature of 350 °C within 180 min. Interestingly, 1 wt% of catalyst in the micro-batch closed system yielded 96% hydrocarbons with 93% n-(C15 + C17) selectivity within 60 min at 330 °C, 38.4 wt% FFA and 5% water content. An examination of the WCO under a series of FFA (0–20%) and water contents (0.5–20 wt%) indicated an enhanced yield of Green Diesel, and increased involvement of the deCOx mechanism. A high water content was found to increase the decomposition of triglycerides into FFAs and promote the DO reaction. The present work demonstrates that WCO with significant levels of water and FFAs generated by the food industry can provide an economical and naturally replenished raw material for the production of Diesel.
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pyro lytic de oxygenation of waste cooking oil for Green Diesel production over ag2o3 la2o3 ac nano catalyst
Journal of Analytical and Applied Pyrolysis, 2019Co-Authors: G Abdulkareemalsultan, Hwei Voon Lee, Nasar Mansir, N Asikinmijan, Zulkarnain Zainal, Aminul Islam, Yun Hin TaufiqyapAbstract:Abstract Green Diesel derived from deoxygenation technology has been developed to replace instability of fatty acid alkyl ester (bioDiesel) due to the presence oxygenated species. Herein, the Green Diesel was synthesized via catalytic deoxygenation (DO) of waste cooking oil (WCO) over synthesized Ag2O3–La2O3/ACnano catalyst under hydrogen-free environment. Based on the study, the effect of silver (Ag) species (10–30 wt%) towards DO reactivity and product distribution was investigated. It was revealed that the Ag2O3(10%)–La2O3(20%)/ACnano formulation resulted in a higher yield (∼89%) of liquid hydrocarbons with majority of Diesel fractions selectivity (n–(C15+C17) at ∼93%. In addition, decarboxylation and decarbonylation reaction processes of the WCO to DO was promoted by the presence of acid and basic active sites on Ag2O3(10%)–La2O3(20%)/ACnano catalyst. The high stability of the Ag2O3(10%)–La2O3(20%)/ACnano catalyst was proven by maintenance of six continuous runs with constant yield (>80%) of hydrocarbons and (>93%) selectivity of n–(C15+C17) under mild reaction conditions.
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production of Green Diesel via cleaner catalytic deoxygenation of jatropha curcas oil
Journal of Cleaner Production, 2017Co-Authors: Hwei Voon Lee, N Asikinmijan, G Abdulkareemalsultan, Aflah Afandi, Yun Hin TaufiqyapAbstract:Abstract Utilization of Green Diesel derived from biomass in industries and transportation has significantly increased energy security by reducing the dependency on the petroleum and balancing the overall Greenhouse gas emission. In the present study, jatropha oil-derived Green Diesel was produced via catalytic deoxygenation process by using multi-walled carbon nanotube (MWCNTs)-supported catalysts (Co/MWCNT, Ni/MWCNT and Ni Co/MWCNT). The use of active bimetallic promoter (Ni Co) showed high catalytic activity in decarboxylation/decarbonylation routes with a total of 80% of saturated and unsaturated hydrocarbon in range of C 8 C 17 . Furthermore, Ni Co/MWCNT showed high selectivity towards C 15 - and C 17 -hydrocarbon, which suggested that the presence of acidity work selectively in mild cracking of triglyceride structure and performed actively in deoxygenation.
Alexis Lycourghiotis - One of the best experts on this subject based on the ideXlab platform.
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w promoted ni al2o3 co precipitated catalysts for Green Diesel production
Fuel Processing Technology, 2021Co-Authors: Christos Papadopoulos, Eleana Kordouli, Kyriakos Bourikas, Christos Kordulis, Labrini Sygellou, Alexis LycourghiotisAbstract:Abstract The promoting action of W in the Ni-Al2O3 co-precipitated catalysts with high nickel loading (31–46 wt% Ni) has been investigated in the selective deoxygenation of sunflower oil and waste cooking oil towards Green Diesel production. A WNi-Al2O3 catalyst containing 8 wt% W and 35 wt% Ni ( Ni Ni + W = 0.9 atomic ratio) proven the most efficient. The detailed characterization of the catalysts allowed an insight concerning the tungsten promoting action. It was attributed to the increase in the catalyst specific surface area and metallic nickel surface area, the acidity regulation, the decrease of the amount of catalytically inactive nickel aluminate formed and to the participation of W5+-oxo species via their defect oxygen sites in the selective deoxygenation network. The optimum reduction – activation temperature was found at 500 °C, where a good compromise between the increase of metallic Ni relative amount, the decrease of the specific surface area and the increase of Ni mean crystal size is achieved.
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Green Diesel production over nickel alumina nanostructured catalysts promoted by copper
Energies, 2020Co-Authors: Mantha Gousi, Eleana Kordouli, Kyriakos Bourikas, Christos Kordulis, Emmanouil Symianakis, S Ladas, Alexis LycourghiotisAbstract:A series of nickel–alumina catalysts promoted by copper containing 1, 2, and 5 wt. % Cu and 59, 58, and 55 wt. % Ni, respectively, (symbols: 59Ni1CuAl, 58Ni2CuAl, 55Ni5CuAl) and a non-promoted catalyst containing 60 wt. % Ni (symbol: 60NiAl) were prepared following a one-step co-precipitation method. They were characterized using various techniques (N2 sorption isotherms, XRD, SEM-EDX, XPS, H2-TPR, NH3-TPD) and evaluated in the selective deoxygenation of sunflower oil using a semi-batch reactor (310 °C, 40 bar of hydrogen, 96 mL/min hydrogen flow rate, and 100 mL/1 g reactant to catalyst ratio). The severe control of the co-precipitation procedure and the direct reduction (without previous calcination) of precursor samples resulted in mesoporous nano-structured catalysts (most of the pores in the range 3–5 nm) exhibiting a high surface area (192–285 m2 g−1). The promoting action of copper is demonstrated for the first time for catalysts with a very small Cu/Ni weight ratio (0.02–0.09). The effect is more pronounced in the catalyst with the medium copper content (58Ni2CuAl) where a 17.2% increase of Green Diesel content in the liquid products has been achieved with respect to the non-promoted catalyst. The copper promoting action was attributed to the increase in the nickel dispersion as well as to the formation of a Ni-Cu alloy being very rich in nickel. A portion of the Ni-Cu alloy nanoparticles is covered by Ni0 and Cu0 nanoparticles in the 59Ni1CuAl and 55Ni5CuAl catalysts, respectively. The maximum promoting action observed in the 58Ni2CuAl catalyst was attributed to the finding that, in this catalyst, there is no considerable masking of the Ni-Cu alloy by Ni0 or Cu0. The relatively low performance of the 55Ni5CuAl catalyst with respect to the other promoted catalysts was attributed, in addition to the partial coverage of Ni-Cu alloy by Cu0, to the remarkably low weak/moderate acidity and relatively high strong acidity exhibited by this catalyst. The former favors selective deoxygenation whereas the latter favors coke formation. Copper addition does not affect the selective-deoxygenation reactions network, which proceeds predominantly via the dehydration-decarbonylation route over all the catalysts studied.
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waste cooking oil transformation into third generation Green Diesel catalyzed by nickel alumina catalysts
Molecular Catalysis, 2020Co-Authors: Ioannis Nikolopoulos, Eleana Kordouli, Kyriakos Bourikas, Christos Kordulis, George Kogkos, Alexis LycourghiotisAbstract:Abstract Three nickel-alumina catalysts were prepared with nickel content 60, 80 and 90 wt % (symbols: 60NiAl, 80NiAl, 90NiAl) following a co-precipitation methodology. The catalysts were characterized and evaluated in the selective deoxygenation of waste cooking oil for the production of third generation Green Diesel under solvent free conditions. Metallic Ni, NiO, and NiAl2O4 were detected in the 60NiAl catalyst. NiAl2O4 is hardly detected in the 80NiAl catalyst but not at all in the 90NiAl catalyst. The extent of reduction of NiO to metallic Ni upon activation is considerably higher in the 80NiAl and 90NiAl samples with respect to the 60NiAl sample resulting in much higher active site population. The increase in the nickel content causes a change in the porous structure and a decrease in the specific surface area. The catalytic performance increases considerably from the 60NiAl catalyst to the 80NiAl one due to the increase in the active site population. The higher catalytic performance of the 80NiAl catalyst with respect to that of the 90NiAl catalyst, exhibiting almost equal active site population, is due to convenient porous structure of 80NiAl catalyst, which hinder the insertion of deleterious bulky compounds present in the waste cooking oil, as well as to its strong acid sites.
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mo promoted ni al2o3 co precipitated catalysts for Green Diesel production
Applied Catalysis B-environmental, 2018Co-Authors: Eleana Kordouli, Kyriakos Bourikas, Christos Kordulis, B Pawelec, J L G Fierro, Alexis LycourghiotisAbstract:Abstract Three Mo promoted Ni-Al2O3 co-precipitation catalysts with practically the same composition (49–52%wtNi, 6-7%wtMo) were prepared using three different co-precipitation modes: co-precipitation at room temperature using ammonia as precipitating agent as well as co-precipitation at higher temperature (110 °C) using ammonia or urea as precipitating agent. The corresponding un-promoted catalysts were also synthesized for comparison. The catalysts were exhaustively characterized using various techniques and evaluated for the selective deoxygenation (SDO) of natural triglycerides using two different feedstocks: sunflower oil (SO) and waste cooked oil (WCO). The catalytic tests were performed under solvent free conditions in a semi-batch reactor at 310 °C, hydrogen pressure 40 bar and very high reactant volume to catalysts mass ratio (100 mL/1 g). The promoting action of the Mo(VI) and Mo(IV) well dispersed oxidic phases, was demonstrated in all cases. This was attributed to the impressive decrease in the size of the nickel nanoparticles and to the inhibition of the formation of the catalytically inactive nickel aluminate. Moreover, the Mo (VI) and Mo(IV) oxidic phases affect the network of the SDO favoring the hydrodeoxygenation of the intermediate alcohols with respect to the decarbonylation of intermediate aldehydes. The catalyst prepared at high co-precipitation temperature using ammonia as precipitating agent was proved to be the most efficient for the SDO of SO. An almost complete transformation of SO into n-C15, n-C16, n-C17, n-C18 (Green Diesel: 97% of liquid products) was obtained under the above mentioned conditions. This catalyst was proved to be very stable. The catalyst prepared at room co-precipitation temperature using ammonia as precipitating agent was proved to be the most efficient for the SDO of WCO (Green Diesel: 76% of liquid products). Its improved efficiency with respect to the other Mo promoted catalysts was attributed to its smaller pore size which prohibits the blockage of active sites located inside the corresponding pores by bulky compounds present in WCO.
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probing the synergistic ratio of the nimo γ al2o3 reduced catalysts for the transformation of natural triglycerides into Green Diesel
Applied Catalysis B-environmental, 2017Co-Authors: Eleana Kordouli, Kyriakos Bourikas, Christos Kordulis, Labrini Sygellou, Alexis LycourghiotisAbstract:Abstract The synergistic atomic ratio, N i N i + M o , of the NiMo/γ-Al2O3 reduced catalysts was investigated for the transformation of natural triglycerides into Green Diesel. A series of catalysts with different atomic ratios 0 ≤ N i N i + M o ≤ 1 and constant atomic surface density (Mo + Ni) = 4 atoms/nm2 was prepared and characterized using adsorption–desorption isotherms, XRD, SEM-EDS, XPS and H2-TPR. The catalysts were evaluated in the selective deoxygenation of sunflower oil performed by hydrotreatment using a semi-batch reactor. For comparison, two additional NiMo/γ-Al2O3 sulphided catalysts were synthesized and tested. The most active reduced catalyst was also tested in the selective deoxygenation of waste cooking oil. MoO3/MoOx (Mo oxidation number between 5 and 4) and Ni0, NiO, NiAl2O4 phases very well dispersed on the support surface and uniformly distributed on the catalysts extrudates have been detected in all cases. The high dispersion of these phases does not practically disturb the texture of the support which exhibits a single peak pore volume distribution centered at about 8–9 nm. The Ni, Mo composition of the catalysts somehow affects the relative amounts of these phases of the same element. It was found that the aforementioned N i N i + M o ratio is located at about 0.8. This is very different to that of the sulphided catalysts which is located at about 0.3 for both the hydrodesulphurization of petroleum fractions and the selective deoxygenation of sunflower oil. An impressive increase of the% yield to hydrocarbons in the Diesel range by a factor of 4.77 was achieved by a simple change of the N i N i + M o atomic ratio in the NiMo/γ-Al2O3 reduced catalysts from 0.3 to 0.8. A complete transformation of both sunflower oil and waste cooking oil into hydrocarbons in the Diesel range was obtained over the most active catalyst at 310 °C, hydrogen pressure 40 bar, reactant volume to catalyst mass ratio equal to 10 ml/g and reaction time equal to 5 h.
Eleana Kordouli - One of the best experts on this subject based on the ideXlab platform.
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w promoted ni al2o3 co precipitated catalysts for Green Diesel production
Fuel Processing Technology, 2021Co-Authors: Christos Papadopoulos, Eleana Kordouli, Kyriakos Bourikas, Christos Kordulis, Labrini Sygellou, Alexis LycourghiotisAbstract:Abstract The promoting action of W in the Ni-Al2O3 co-precipitated catalysts with high nickel loading (31–46 wt% Ni) has been investigated in the selective deoxygenation of sunflower oil and waste cooking oil towards Green Diesel production. A WNi-Al2O3 catalyst containing 8 wt% W and 35 wt% Ni ( Ni Ni + W = 0.9 atomic ratio) proven the most efficient. The detailed characterization of the catalysts allowed an insight concerning the tungsten promoting action. It was attributed to the increase in the catalyst specific surface area and metallic nickel surface area, the acidity regulation, the decrease of the amount of catalytically inactive nickel aluminate formed and to the participation of W5+-oxo species via their defect oxygen sites in the selective deoxygenation network. The optimum reduction – activation temperature was found at 500 °C, where a good compromise between the increase of metallic Ni relative amount, the decrease of the specific surface area and the increase of Ni mean crystal size is achieved.
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Green Diesel production over nickel alumina nanostructured catalysts promoted by zinc
Catalysis Today, 2020Co-Authors: Mantha Gousi, Eleana Kordouli, Kyriakos Bourikas, Christos Kordulis, S Ladas, Emmanouil Simianakis, George D PanagiotouAbstract:Abstract Following the one step co-precipitation technique we have synthesized a series of Ni-Zn catalysts supported on alumina. The series involves one non-promoted sample containing 60 wt % Ni and three zinc promoted samples containing 1, 2 and 5 wt % Zn and 59, 58 and 55 wt % Ni, respectively. The specimens were characterized using nitrogen sorption isotherms, H2-TPR, NH3-TPD, XRD, SEM-EDX, TEM and XPS. The catalytic performance of the samples prepared was evaluated in the selective deoxygenation of sunflower oil using a semi-batch reactor (310 °C, 40 bar of hydrogen, hydrogen flow rate equal to 100 mL/min and reactant to catalyst ratio equal to 100 mL/g). The control of the co-precipitation procedure and the direct reduction of dried precipitate resulted to mesoporous nano-structured catalysts with high surface area (247–290 m2 g−1). The non-promoted sample was mainly comprised from NiAl2O4 particles and the promoted ones from Ni-Zn alloys and intermetallic oxo-phases (IMPs) supported on largely amorphous Al2O3 nano-grains. Zinc increased the total yield of alkanes in the Diesel range (n-15, n-16, n-17, n-18) though it does not affect the mechanistic scheme of the selective deoxygenation of sunflower oil which is largely realized via decarbonylation/decarboxylation. The promoting action of zinc was attributed to the favoring of the Ni-Zn alloys and IMPs formation. It is more pronounced in the sample with the medium zinc content (58 wt % Ni, 2 wt % Zn, 40 wt % Al2O3) in which an increase of 18% in the total yield of hydrocarbons has been obtained. The maximization of the zinc promoting action in this sample reflects the good compromise between the extent of alloying and surface acidity.
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Green Diesel production over nickel alumina nanostructured catalysts promoted by copper
Energies, 2020Co-Authors: Mantha Gousi, Eleana Kordouli, Kyriakos Bourikas, Christos Kordulis, Emmanouil Symianakis, S Ladas, Alexis LycourghiotisAbstract:A series of nickel–alumina catalysts promoted by copper containing 1, 2, and 5 wt. % Cu and 59, 58, and 55 wt. % Ni, respectively, (symbols: 59Ni1CuAl, 58Ni2CuAl, 55Ni5CuAl) and a non-promoted catalyst containing 60 wt. % Ni (symbol: 60NiAl) were prepared following a one-step co-precipitation method. They were characterized using various techniques (N2 sorption isotherms, XRD, SEM-EDX, XPS, H2-TPR, NH3-TPD) and evaluated in the selective deoxygenation of sunflower oil using a semi-batch reactor (310 °C, 40 bar of hydrogen, 96 mL/min hydrogen flow rate, and 100 mL/1 g reactant to catalyst ratio). The severe control of the co-precipitation procedure and the direct reduction (without previous calcination) of precursor samples resulted in mesoporous nano-structured catalysts (most of the pores in the range 3–5 nm) exhibiting a high surface area (192–285 m2 g−1). The promoting action of copper is demonstrated for the first time for catalysts with a very small Cu/Ni weight ratio (0.02–0.09). The effect is more pronounced in the catalyst with the medium copper content (58Ni2CuAl) where a 17.2% increase of Green Diesel content in the liquid products has been achieved with respect to the non-promoted catalyst. The copper promoting action was attributed to the increase in the nickel dispersion as well as to the formation of a Ni-Cu alloy being very rich in nickel. A portion of the Ni-Cu alloy nanoparticles is covered by Ni0 and Cu0 nanoparticles in the 59Ni1CuAl and 55Ni5CuAl catalysts, respectively. The maximum promoting action observed in the 58Ni2CuAl catalyst was attributed to the finding that, in this catalyst, there is no considerable masking of the Ni-Cu alloy by Ni0 or Cu0. The relatively low performance of the 55Ni5CuAl catalyst with respect to the other promoted catalysts was attributed, in addition to the partial coverage of Ni-Cu alloy by Cu0, to the remarkably low weak/moderate acidity and relatively high strong acidity exhibited by this catalyst. The former favors selective deoxygenation whereas the latter favors coke formation. Copper addition does not affect the selective-deoxygenation reactions network, which proceeds predominantly via the dehydration-decarbonylation route over all the catalysts studied.
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waste cooking oil transformation into third generation Green Diesel catalyzed by nickel alumina catalysts
Molecular Catalysis, 2020Co-Authors: Ioannis Nikolopoulos, Eleana Kordouli, Kyriakos Bourikas, Christos Kordulis, George Kogkos, Alexis LycourghiotisAbstract:Abstract Three nickel-alumina catalysts were prepared with nickel content 60, 80 and 90 wt % (symbols: 60NiAl, 80NiAl, 90NiAl) following a co-precipitation methodology. The catalysts were characterized and evaluated in the selective deoxygenation of waste cooking oil for the production of third generation Green Diesel under solvent free conditions. Metallic Ni, NiO, and NiAl2O4 were detected in the 60NiAl catalyst. NiAl2O4 is hardly detected in the 80NiAl catalyst but not at all in the 90NiAl catalyst. The extent of reduction of NiO to metallic Ni upon activation is considerably higher in the 80NiAl and 90NiAl samples with respect to the 60NiAl sample resulting in much higher active site population. The increase in the nickel content causes a change in the porous structure and a decrease in the specific surface area. The catalytic performance increases considerably from the 60NiAl catalyst to the 80NiAl one due to the increase in the active site population. The higher catalytic performance of the 80NiAl catalyst with respect to that of the 90NiAl catalyst, exhibiting almost equal active site population, is due to convenient porous structure of 80NiAl catalyst, which hinder the insertion of deleterious bulky compounds present in the waste cooking oil, as well as to its strong acid sites.
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nickel catalysts supported on palygorskite for transformation of waste cooking oils into Green Diesel
Applied Catalysis B-environmental, 2019Co-Authors: Eleana Kordouli, Kyriakos Bourikas, Christos Kordulis, Sotiris Lycourghiotis, Labrini SygellouAbstract:Abstract Nickel catalysts supported on palygorskite of varying Ni content were synthesized following the deposition–precipitation method. The catalysts were characterized using various techniques and evaluated in a semi-batch reactor for the transformation of waste cooking oils (WCO) into Green Diesel at 310 °C and hydrogen pressure 40 bar. The nickel nanoparticles supported on palygorskite were proved to be very active. The conversion of the WCO was about 100%. The Green Diesel content of the liquid product depends mainly on the nickel surface exposed per gram of catalyst, following a volcano like trend and maximized (81.9 wt %) over the sample with 30 wt % Ni. Taking into account the very high ratio of WCO volume to catalyst mass (100 mL/g) and that the evaluation of the catalysts was performed under solvent free conditions, these results demonstrate the successful use of mineral palygorskite for developing promising “natural catalysts” for Green Diesel production.
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w promoted ni al2o3 co precipitated catalysts for Green Diesel production
Fuel Processing Technology, 2021Co-Authors: Christos Papadopoulos, Eleana Kordouli, Kyriakos Bourikas, Christos Kordulis, Labrini Sygellou, Alexis LycourghiotisAbstract:Abstract The promoting action of W in the Ni-Al2O3 co-precipitated catalysts with high nickel loading (31–46 wt% Ni) has been investigated in the selective deoxygenation of sunflower oil and waste cooking oil towards Green Diesel production. A WNi-Al2O3 catalyst containing 8 wt% W and 35 wt% Ni ( Ni Ni + W = 0.9 atomic ratio) proven the most efficient. The detailed characterization of the catalysts allowed an insight concerning the tungsten promoting action. It was attributed to the increase in the catalyst specific surface area and metallic nickel surface area, the acidity regulation, the decrease of the amount of catalytically inactive nickel aluminate formed and to the participation of W5+-oxo species via their defect oxygen sites in the selective deoxygenation network. The optimum reduction – activation temperature was found at 500 °C, where a good compromise between the increase of metallic Ni relative amount, the decrease of the specific surface area and the increase of Ni mean crystal size is achieved.
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Green Diesel production over nickel alumina nanostructured catalysts promoted by zinc
Catalysis Today, 2020Co-Authors: Mantha Gousi, Eleana Kordouli, Kyriakos Bourikas, Christos Kordulis, S Ladas, Emmanouil Simianakis, George D PanagiotouAbstract:Abstract Following the one step co-precipitation technique we have synthesized a series of Ni-Zn catalysts supported on alumina. The series involves one non-promoted sample containing 60 wt % Ni and three zinc promoted samples containing 1, 2 and 5 wt % Zn and 59, 58 and 55 wt % Ni, respectively. The specimens were characterized using nitrogen sorption isotherms, H2-TPR, NH3-TPD, XRD, SEM-EDX, TEM and XPS. The catalytic performance of the samples prepared was evaluated in the selective deoxygenation of sunflower oil using a semi-batch reactor (310 °C, 40 bar of hydrogen, hydrogen flow rate equal to 100 mL/min and reactant to catalyst ratio equal to 100 mL/g). The control of the co-precipitation procedure and the direct reduction of dried precipitate resulted to mesoporous nano-structured catalysts with high surface area (247–290 m2 g−1). The non-promoted sample was mainly comprised from NiAl2O4 particles and the promoted ones from Ni-Zn alloys and intermetallic oxo-phases (IMPs) supported on largely amorphous Al2O3 nano-grains. Zinc increased the total yield of alkanes in the Diesel range (n-15, n-16, n-17, n-18) though it does not affect the mechanistic scheme of the selective deoxygenation of sunflower oil which is largely realized via decarbonylation/decarboxylation. The promoting action of zinc was attributed to the favoring of the Ni-Zn alloys and IMPs formation. It is more pronounced in the sample with the medium zinc content (58 wt % Ni, 2 wt % Zn, 40 wt % Al2O3) in which an increase of 18% in the total yield of hydrocarbons has been obtained. The maximization of the zinc promoting action in this sample reflects the good compromise between the extent of alloying and surface acidity.
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Green Diesel production over nickel alumina nanostructured catalysts promoted by copper
Energies, 2020Co-Authors: Mantha Gousi, Eleana Kordouli, Kyriakos Bourikas, Christos Kordulis, Emmanouil Symianakis, S Ladas, Alexis LycourghiotisAbstract:A series of nickel–alumina catalysts promoted by copper containing 1, 2, and 5 wt. % Cu and 59, 58, and 55 wt. % Ni, respectively, (symbols: 59Ni1CuAl, 58Ni2CuAl, 55Ni5CuAl) and a non-promoted catalyst containing 60 wt. % Ni (symbol: 60NiAl) were prepared following a one-step co-precipitation method. They were characterized using various techniques (N2 sorption isotherms, XRD, SEM-EDX, XPS, H2-TPR, NH3-TPD) and evaluated in the selective deoxygenation of sunflower oil using a semi-batch reactor (310 °C, 40 bar of hydrogen, 96 mL/min hydrogen flow rate, and 100 mL/1 g reactant to catalyst ratio). The severe control of the co-precipitation procedure and the direct reduction (without previous calcination) of precursor samples resulted in mesoporous nano-structured catalysts (most of the pores in the range 3–5 nm) exhibiting a high surface area (192–285 m2 g−1). The promoting action of copper is demonstrated for the first time for catalysts with a very small Cu/Ni weight ratio (0.02–0.09). The effect is more pronounced in the catalyst with the medium copper content (58Ni2CuAl) where a 17.2% increase of Green Diesel content in the liquid products has been achieved with respect to the non-promoted catalyst. The copper promoting action was attributed to the increase in the nickel dispersion as well as to the formation of a Ni-Cu alloy being very rich in nickel. A portion of the Ni-Cu alloy nanoparticles is covered by Ni0 and Cu0 nanoparticles in the 59Ni1CuAl and 55Ni5CuAl catalysts, respectively. The maximum promoting action observed in the 58Ni2CuAl catalyst was attributed to the finding that, in this catalyst, there is no considerable masking of the Ni-Cu alloy by Ni0 or Cu0. The relatively low performance of the 55Ni5CuAl catalyst with respect to the other promoted catalysts was attributed, in addition to the partial coverage of Ni-Cu alloy by Cu0, to the remarkably low weak/moderate acidity and relatively high strong acidity exhibited by this catalyst. The former favors selective deoxygenation whereas the latter favors coke formation. Copper addition does not affect the selective-deoxygenation reactions network, which proceeds predominantly via the dehydration-decarbonylation route over all the catalysts studied.
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waste cooking oil transformation into third generation Green Diesel catalyzed by nickel alumina catalysts
Molecular Catalysis, 2020Co-Authors: Ioannis Nikolopoulos, Eleana Kordouli, Kyriakos Bourikas, Christos Kordulis, George Kogkos, Alexis LycourghiotisAbstract:Abstract Three nickel-alumina catalysts were prepared with nickel content 60, 80 and 90 wt % (symbols: 60NiAl, 80NiAl, 90NiAl) following a co-precipitation methodology. The catalysts were characterized and evaluated in the selective deoxygenation of waste cooking oil for the production of third generation Green Diesel under solvent free conditions. Metallic Ni, NiO, and NiAl2O4 were detected in the 60NiAl catalyst. NiAl2O4 is hardly detected in the 80NiAl catalyst but not at all in the 90NiAl catalyst. The extent of reduction of NiO to metallic Ni upon activation is considerably higher in the 80NiAl and 90NiAl samples with respect to the 60NiAl sample resulting in much higher active site population. The increase in the nickel content causes a change in the porous structure and a decrease in the specific surface area. The catalytic performance increases considerably from the 60NiAl catalyst to the 80NiAl one due to the increase in the active site population. The higher catalytic performance of the 80NiAl catalyst with respect to that of the 90NiAl catalyst, exhibiting almost equal active site population, is due to convenient porous structure of 80NiAl catalyst, which hinder the insertion of deleterious bulky compounds present in the waste cooking oil, as well as to its strong acid sites.
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nickel catalysts supported on palygorskite for transformation of waste cooking oils into Green Diesel
Applied Catalysis B-environmental, 2019Co-Authors: Eleana Kordouli, Kyriakos Bourikas, Christos Kordulis, Sotiris Lycourghiotis, Labrini SygellouAbstract:Abstract Nickel catalysts supported on palygorskite of varying Ni content were synthesized following the deposition–precipitation method. The catalysts were characterized using various techniques and evaluated in a semi-batch reactor for the transformation of waste cooking oils (WCO) into Green Diesel at 310 °C and hydrogen pressure 40 bar. The nickel nanoparticles supported on palygorskite were proved to be very active. The conversion of the WCO was about 100%. The Green Diesel content of the liquid product depends mainly on the nickel surface exposed per gram of catalyst, following a volcano like trend and maximized (81.9 wt %) over the sample with 30 wt % Ni. Taking into account the very high ratio of WCO volume to catalyst mass (100 mL/g) and that the evaluation of the catalysts was performed under solvent free conditions, these results demonstrate the successful use of mineral palygorskite for developing promising “natural catalysts” for Green Diesel production.
