Kızılkaya, Ali Can
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Kızılkaya, A. C.
Kızılkaya, Ali C.
Kızılkaya, AC
Kazalkaya, Ali C.
Kizilkaya, A. C.
Kizilkaya, AC
Kizilkaya, Ali C.
Kizilkaya, Ali Can
Kızılkaya, Ali C.
Kızılkaya, AC
Kazalkaya, Ali C.
Kizilkaya, A. C.
Kizilkaya, AC
Kizilkaya, Ali C.
Kizilkaya, Ali Can
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alicankizilkaya@iyte.edu.tr
Main Affiliation
03.02. Department of Chemical Engineering
Status
Current Staff
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Sustainable Development Goals
1NO POVERTY
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2ZERO HUNGER
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3GOOD HEALTH AND WELL-BEING
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4QUALITY EDUCATION
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5GENDER EQUALITY
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6CLEAN WATER AND SANITATION
1
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7AFFORDABLE AND CLEAN ENERGY
4
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8DECENT WORK AND ECONOMIC GROWTH
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9INDUSTRY, INNOVATION AND INFRASTRUCTURE
6
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10REDUCED INEQUALITIES
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11SUSTAINABLE CITIES AND COMMUNITIES
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12RESPONSIBLE CONSUMPTION AND PRODUCTION
2
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13CLIMATE ACTION
6
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14LIFE BELOW WATER
2
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15LIFE ON LAND
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16PEACE, JUSTICE AND STRONG INSTITUTIONS
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17PARTNERSHIPS FOR THE GOALS
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Documents
17
Citations
354
h-index
10
Documents
15
Citations
342
Scholarly Output
18
Articles
10
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12013/5827
Supervised MSc Theses
7
Supervised PhD Theses
0
WoS Citation Count
118
Scopus Citation Count
131
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0
Projects
1
WoS Citations per Publication
6.56
Scopus Citations per Publication
7.28
Open Access Source
11
Supervised Theses
7
| Journal | Count |
|---|---|
| Sakarya University Journal of Science | 2 |
| Catalysts | 2 |
| ACS Catalysis | 2 |
| Catalysis Today | 1 |
| Materials Chemistry and Physics | 1 |
Current Page: 1 / 2
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18 results
Scholarly Output Search Results
Now showing 1 - 10 of 18
Book Part Citation - Scopus: 3The Future of Fossil Fuels(World Scientific Publishing Co. Pte. Ltd., 2024) Kizilkaya,A.C.[No abstract available]Article Design of Sulfur Resistant Cobalt Catalysts by Boron Promotion: Atomic Scale Insights(Sakarya University, 2024) Kızılkaya, A.C.The effect of boron promotion on atomic sulfur formation by hydrogen sulfide dissociation on Co(111), flat surfaces of cobalt nanoparticles, was investigated using Density Functional Theory calculations. The results show that on clean Co(111), hydrogen sulfide dissociation proceeds fast due to low activation barriers, yielding atomic sulfur on the cobalt surfaces. Boron promotion hinders the dissociation of hydrogen sulfide due to increased activation barriers. Furthermore, boron prevents the interaction of sulfur compounds with cobalt surface atoms, as these poisons bind on boron. The findings indicate that boron is an effective promoter that can be used to design sulfur resistant cobalt catalysts. © 2024, Sakarya University. All rights reserved.Article Citation - WoS: 6Citation - Scopus: 9Mechanistic Insights Into the Effect of Sulfur on the Selectivity of Cobalt-Catalyzed Fischer–tropsch Synthesis: a Dft Study(MDPI, 2022) Dağa, Yağmur; Kızılkaya, Ali CanSulfur is a common poison for cobalt-catalyzed Fischer–Tropsch Synthesis (FTS). Alt-hough its effects on catalytic activity are well documented, its effects on selectivity are controversial. Here, we investigated the effects of sulfur-covered cobalt surfaces on the selectivity of FTS using density functional theory (DFT) calculations. Our results indicated that sulfur on the surface of Co(111) resulted in a significant decrease in the adsorption energies of CO, HCO and acetylene, while the binding of H and CH species were not significantly affected. These findings indicate that sulfur increased the surface H/CO coverage ratio while inhibiting the adsorption of carbon chains. The elementary reactions of H-assisted CO dissociation, carbon and oxygen hydrogenation and CH coupling were also investigated on both clean and sulfur-covered Co(111). The results indicated that sulfur decreased the activation barriers for carbon and oxygen hydrogenation, while increasing the barriers for CO dissociation and CH coupling. Combining the results on elementary reactions with the modification of adsorption energies, we concluded that the intrinsic effect of sulfur on the selectivity of cobalt-catalyzed FTS is to increase the selectivity to methane and saturated short-chain hy-drocarbons, while decreasing the selectivity to olefins and long-chain hydrocarbons.Master Thesis Molecular Modelling of the Effect of Alkali Promoters on Co Adsorption and Dissociation on the Co(111) Surface(2023) Özbek, Özüm; Kızılkaya, Ali CanFischer-Tropsch Synthesis (FTS) is a surface polymerization process that has been industrially used to convert non-petroleum feedstocks to synthetic transportation fuels. Modification with an alkali promoter of the Co-based catalysts provided promising results to obtain hydrocarbons with enhanced olefin content in FTS. Activation of CO is the key factor to achieve desired end products in FTS, yet the mechanism related to the CO dissociation behavior on alkali promoted cobalt surfaces remains unknown. This study aims to examine the impact of alkali promoters (Li, Na, K) on the adsorption and dissociation characteristics of CO on the Co(111) surface using Density Functional Theory (DFT). Our results revealed that CO adsorption energy increased by 32-37% with alkali addition, yet H adsorption energy remained relatively unchanged. The effect of alkali addition on CO dissociation routes were also examined. The high activation barrier (>200 kJ/mol) makes it improbable for direct CO dissociation to occur on alkali promoted Co(111) surfaces under FTS conditions. For H-assisted pathways, alkali addition increased the activation barrier for HCO and H2CO dissociation, overall reducing the H-assisted CO dissociation rate. It was found that alkali addition makes the surface more carbophilic since the C adsorption energy increased by 7-11% upon alkali addition. Also, with increasing C concentration on the Co(111) surface, subsurface carbon geometries became more stable. Ultimately, it is concluded that alkali promoters of Li, Na and K have similar effects on CO adsorption and dissociation on the Co(111) surface.Master Thesis Design of Advanced Process Control System for Delayed Coker Unit(2023) Zihinli, İrem; Kızılkaya, Ali CanIt is essential for refineries to optimize the upgrading vacuum residue (VR) processes due to reducing of conventional light crude oil resources and increasing of fuel global demands. Delayed coking is a thermal cracking process used in refineries to upgrade and convert vacuum residuum into liquid and gas product streams including Light Coker Gas Oil (LCGO), Heavy Coker Gas Oil (HCGO), Sour Liquefied Petroleum Gas (LPG), Sour Coker Product Gas, Stabilized Naphtha and Petroleum Coke as a solid concentrated carbon material. Delayed coking is a semi-batch process where one or more pairs of coke drums are used for the thermal cracking and coking process. Simultaneously in each pair of coke drums, the feed stream is switched between two drums and one drum is online for the coking process while the other drum is offline undergoing decoking. The switching of the coke drums severely destabilizes the operation of the main fractionator and downstream process units. Applying advanced control concepts minimizes the disturbances and improves product quality and unit stability. Delayed coking is one of the most difficult refinery units to operate and control due to disturbances. Industrial chemical processes must operate at maximum efficiency and one of the ways to save energy and still obtain high quality product by using Advanced Process Control (APC) systems. The objective of thesis is to design an advanced process control system for main fractionator column of the delayed coker unit using Honeywell RMPCT. The aim of the APC is to decrease standard deviation of LCGO Final Boiling Point (FBP) quality in main fractionator column during steady state operation. The methods used in this thesis are the determination of the controller matrix and the application of pre-step and main tests to obtain process models for the advanced process control. According to obtained results, standard deviation for the LCGO FBP quality results are compared before and after APC implementation. It is shown that when the APC is turned on, the standard deviation of the LCGO product FBP quality is decreased by 3 ℃.Master Thesis The Influence of Inorganic and Organic Coating Layers on the Corrosion Behaviour of Coil Coated Aluminum Substrates(Izmir Institute of Technology, 2020) Uç, Merve; Kızılkaya, Ali CanOrganic coil coated aluminum substrates are one of the most widely used materials for construction industry. These coated substrates typically consist of 4 separate layers, the aluminum substrate, the inorganic conversion coating (resulting from the pretreatment application), and the organic coating layers that are called the primer and the topcoat. From industrial experience, it is not clearly and quantitatively determined how these layers contribute to the different processes that occur during corrosion, such as water uptake (diffusion of water through the coating) and the corrosion reactions that take place on the substrate. In this thesis, the formation of the inorganic conversion coating as a function of the pretreatment application parameters, immersion time, temperature and pH, and the individual effects of inorganic and organic coating layers on corrosion are investigated. The structure of the various surfaces formed after coating application and after corrosion testing by Neutral Salt Spray Test (NSST) is investigated by Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX), X-ray Fluorensence Spectrometer (XRF) and Atomic Force Microscopy (AFM) analysis, while their anticorrosive properties are determined by Electrochemical Impedance Spectroscopy (EIS). The results indicate that the formation of the pretreatment layer is enhanced continuously as function of temperature and immersion time, within the values investigated, while for pH an optimum is observed. The investigation of the corrosion resistance of substrates coated with different coating layers reveal that without organic coating layers, the substrates corrode much faster, indicating the importance of water diffusion on the corrosion reactions.Master Thesis Effect of Sulfur on the Elementary Reactions of Fischer-Tropsch Synthesis on Cobalt Surfaces(Izmir Institute of Technology, 2020) Dağa, Yağmur; Kızılkaya, Ali CanIndustrial observations indicate that sulfur acts a poison for Fischer-Tropsch Synthesis (FTS) and surface science studies show that sulfur blocks the adsorption sites for reactants on cobalt surfaces. However, various experimental studies have indicated conflicting results about the effect of sulfur on cobalt FTS catalyst activity and selectivity. This study aims to clarify the effect of sulfur on cobalt FTS catalysts by molecular modelling of the elementary reactions of FTS on surfaces that are present on sulfur covered cobalt surfaces that are present in fcc-Co nanoparticles, using Density Functional Theory (DFT). For 0.25 ML sulfur coverage, it is found that on bare, C and O covered surfaces, S is the main dissociation product, while HS can be present on low coverages. Atomic sulfur decreases the adsorption energies of all species investigated, while the decrease is more pronounced for CO compared to H2. The effect of S on the elementary FTS reactions direct and H-assisted CO dissociation, carbon hydrogenation, carbon coupling and oxygen removal are also investigated. The results indicate that S inhibits mainly the oxygen removal reaction, in terms of both H2O and CO2. CO dissociation is not inhibited but rather slowed down, due to increasing activation barriers. It is also found that carbon hydrogenation barriers are significantly decreased, while carbon coupling barriers are unaffected. These results indicate that the intrinsic effect of sulfur poisoning would be to increase methane selectivity, while decreasing the selectivity to long chain hydrocarbons.Article Citation - WoS: 13Citation - Scopus: 13Application of Work Function Measurements in the Study of Surface Catalyzed Reactions on Rh(1 0 0)(Taylor & Francis, 2018) Çağlar, Başar; Kızılkaya, Ali Can; Niemantsverdriet, J. W. (Hans); Weststrated, C. J. (Kees-Jan)The present article aims to show how work function measurements (WF) can be applied in the study of elementary surface reaction steps on metallic single crystal surfaces. The work function itself can in many cases not be interpreted directly, as it lacks direct information on structural and chemical nature of the surface and adsorbates, but it can be a powerful tool when used together with other surface science techniques which provide information on the chemical nature of the adsorbed species. We here, illustrate the usefulness of work function measurements using Rh(100) as our model catalyst. The examples presented include work function measurements during adsorption, surface reaction, and desorption of a variety of molecules relevant for heterogeneous catalysis. Surface coverage of adsorbates, isosteric heat of adsorption, and kinetic parameters for desorption, desorption/decomposition temperatures of surface species, different reaction regimes were determined by WF with the aid of other surface science techniques.Master Thesis Mechanistic Investigation of Carbon Dioxide Hydrogenation on Bimetallic Iron-Cobalt Surfaces by Density Functional Theory(2023) Tunçer, Dilan; Kızılkaya, Ali CanKüresel CO2 emisyonundaki artışa bağlı olarak iklim değişikliği, yalnızca CO2 üretiminin azaltılmasındaki önemi artırmakla kalmadı, aynı zamanda katalitik CO2 dönüşümü yoluyla kimyasalların ve yakıtların üretiminde kullanılmasının önemini de artırdı. Aktif ve seçici katalizörlerin rasyonel tasarımı, bu proseslerin endüstriyel uygulamalarına yönelik kritik öneme sahiptir. Bu tezde, C1 hidrokarbonların üretimi için CO2 hidrojenasyonunun mekanizmasını araştırmak ve FeCo bimetalik katalizörlerin (111) yüzeyindeki yapı-aktivite ilişkisinin atomik düzeyde anlaşılmasını sağlamak ve tasarıma rehberlik etmek için ilk prensiplere dayalı hesaplamalı bir çalışma yapıldı. Bu tezde, fcc-Co(111) ve Fe-katkılı Co(111) [FeCo(111)] yüzeyleri üzerinde CO2 hidrojenasyonunun C1 hidrokarbonlara verdiği temel reaksiyonların kinetiği, yoğunluk fonksiyonel teorisi (YFT) kullanılarak karşılaştırıldı. Araştırmamız Fe'nin Co(111) yüzeyine eklenmesi ile birlikte, CO2 aktivasyonunu desteklemesine rağmen genel reaksiyon hızını hafifçe azalttığını ortaya çıkardı. 1 ML Fe-katkılı Co(111) yüzeyinin daha düşük atomik H kapsamaları ve daha yüksek aktivasyon bariyerleri nedeniyle hidrojenasyon reaksiyonlarını engellemesi Fe'nin Lewis bazik karakterine atfedilmiştir. Fe'in katılması temel olarak kobalt yüzeylerinden oksijenin ayrılmasını engellemektedir. Bu nedenle, Fe katkısının, CO2 hidrojenasyonu sırasında bimetalik FeCo katalizörleri üzerinde oksidik fazların oluşumunu teşvik etmesi beklenmektedir.Article Citation - WoS: 6Citation - Scopus: 6Effect of Ammonia on Cobalt Fischer-Tropsch Synthesis Catalysts: a Surface Science Approach(Royal Society of Chemistry, 2019) Kızılkaya, Ali Can; Niemantsverdriet, J. W.; Weststrate, C. J.Ammonia adsorption and decomposition on defect-rich hcp-Co(0001) surfaces were investigated under ultra-high vacuum conditions in order to provide a fundamental explanation for industrially observed ammonia poisoning of cobalt based Fischer-Tropsch synthesis (FTS) catalysts. Temperature-programmed desorption, infrared spectroscopy and work function measurements indicate that undercoordinated sites bind ammonia stronger than sites on flat Co(0001), and they also induce its dehydrogenation. Density functional theory calculations were employed to explore the reactivity of defective Co surfaces using the fcc-Co(211) as a model. The results indicate that the decomposition products (NH x ) adsorb strongly on or around the step site on fcc-Co(211). We find that NH (+2H ad ), adsorbed in the threefold site on the upper terrace, is equally stable as NH 2 (+H ad ), adsorbed in the bridge position at the step edge, both being significantly more stable than the equivalent species adsorbed on the flat Co(0001). The calculated activation barriers for NH 3,ad dehydrogenation steps are in reasonable agreement with the barriers obtained by fitting experimental data. Based on these fundamental insights, poisoning of cobalt nanoparticles during FTS by NH 3 contaminants can be linked mainly to the blocking of undercoordinated sites by strongly adsorbed NH 2 species.