Pioneering Innovations in Catalysis

The Process and Reactor Design (PRT) LAB at Istanbul University-Cerrahpasa, established approximately 20 years ago by Prof. Dr. Mehmet Ali Gürkaynak (Present members: Prof. Dr. Faruk Öksüzömer, Assoc. Prof. Dr. Tuba Gürkaynak Altınçekiç, Assoc. Prof. Dr. Hasan Özdemir, Assoc. Prof. Dr. Vedat Sarıboğa), has been a cornerstone in the field of Chemical Engineering, specializing in catalyst synthesis. Our group, currently composed of dedicated researchers and scientists, has consistently aimed to contribute to the advancement of Turkey's scientific capabilities, ultimately striving to make the nation stronger and self-sufficient.

Historical Background and Evolution of Research Focus

The PRT LAB began its journey with an intense focus on the production of electrolytes, anodes and cathodes for fuel cells, a field spearheaded by Professor Dr. Faruk Öksüzömer. The initial success in this area established a solid foundation for the lab's reputation in the realm of sustainable energy solutions. Over time, as the research on fuel cells reached a saturation point, our attention pivoted towards the burgeoning field of hydrogen production and dissociation, recognizing its critical importance in the future of clean energy.

Current Research Projects

Today, our lab's research portfolio encompasses three primary areas, each led by esteemed experts in their respective fields:

    1. Production and Synthesis of Fuel Cells Components (Electrolyte-Anode-Cathode)

    Although our focus has shifted, the legacy of fuel cell research remains significant. This segment of our work involves the development of advanced electrolytes, aiming to enhance the efficiency and durability of fuel cells.

    2. Catalyst Synthesis and Characterization for Hydrogen Technologies (Hydrogen -Methanol -SynGas)

    This research stream is dedicated to the synthesis and detailed characterization of catalysts that facilitate efficient hydrogen production. The goal is to optimize the catalytic processes to achieve higher yields and lower energy consumption, addressing the global need for sustainable hydrogen as a clean fuel source.

    3. Production of Metal Fuels and Oxidizing Catalysts for Solid Rocket Propellants

    Currently, the most prominent project in our lab focuses on the development of metal fuels and oxidizing catalysts specifically designed for solid rocket propellants. This research is pivotal in enhancing the performance and safety of rocket propulsion systems, which is crucial for both defense and space exploration initiatives.

Vision and Future Goals

Despite the dynamic nature of our research areas, the core mission of the PRT LAB has always been clear: to contribute to the technological and scientific advancement of Turkey, thereby strengthening its independence and global standing. In addition to our academic endeavors, we are deeply committed to nurturing skilled professionals who will become leading researchers in the Turkish industry. We actively collaborate with leading firms (TÜPRAŞ, Aygaz, Abdi İbrahim etc.) and universities (Özyeğin, Kocaeli, Yalova) in Turkey ensuring our graduates are well-equipped to excel in the industrial sector.

Moreover, our lab seeks to bridge the gap between academia and industry through joint industrial projects. These collaborations allow us to remain closely connected with the practical applications of our research, ensuring that our scientific advancements have direct, impactful contributions to the industry.

As we progress, our commitment to excellence in research and our dedication to fostering a collaborative and innovative environment remain unwavering. We look forward to furthering our contributions to the scientific community and to supporting the development of technologies that have the potential to make significant impacts on both national and global scales.

Considerable Projects and Papers

Production and Synthesis of Fuel Cell Components

Revealing the Characteristics of CuCeO2 Anode Structure in Solid Oxide Fuel Cells (2017-2018 BAP Project)

In this project, the optimum compositions for a Cu-CeO2-YSZ anode were introduced as a solid oxide fuel cell anode structure. Fort his purpose, the minimum Cu content, a suitable infiltration technique and the optimum CeO2 amounts were determined. The continuum percolation limit of metallic Cu was demonstrated to be 30% by mass in the YSZ matrix. The simultaneous and sequential impregnation of Cu and CeO2 salt solutions was investigated using XRD and SEM techniques. It was concluded that the phase distribution in the YSZ scaffold was more efficient and that there was no chemical interaction between Cu and CeO2 during the co-calcination process with simultaneous infiltration. The current-voltage measurements showed that up to Cu/CeO2 at 70/30, the electrochemical performance of the cell increased and then decreased for 60/40. The corresponding optimal Cu/CeO2 loading was investigated using single cell I-V characterization, and a 35% Cu-15% CeO2-50% YSZ cermet structure is the proposed ideal cell composition.

Determination Of the Most Suitable Synthesis Method and Preparation Conditions For The Preparation Of Sm0.2Ce0.8O1.9 Based Electrolyte Materials With Superior Performance In Solid Oxide Fuel Cells (2017-2019 TÜBİTAK-3001 Project) 

Solid oxide fuel cells (SOFCs) are energy conversion devices that generate electricity through the electrochemical reaction of a fuel with oxygen ions transported across an ion-conducting electrolyte. SOFCs operate on the principle of ion transport and fuel reaction, creating an electrical voltage through an oxygen ion-conducting electrolyte from the air electrode (cathode) to the fuel electrode (anode). The solid electrolytes used in these cells must exhibit rapid ion conduction, negligible electrical conductivity, and thermodynamic stability over a wide range of temperatures and oxygen partial pressures. Additionally, these electrolytes must be compatible with electrode materials and other components in terms of thermal expansion, exhibit negligible component evaporation, possess suitable mechanical properties, and interact minimally with electrode materials under operating conditions.

Among solid electrolytes for intermediate-temperature SOFCs, Sm-doped CeO2 (Ce0.8Sm0.2O1.9, commonly referred to as SDC) shows great promise. Compared to doped ZrO2, SDC provides conductivity values around 1000 ºC in the intermediate temperature range (600-800 ºC) and at very low oxygen partial pressures (~10−20 atm). In this project, ceria powders doped with 20 mol% Sm were synthesized using 20 different methods, including various precipitation, combustion, and encapsulation techniques. The synthesized powders were characterized using XRD, TGA, and SEM. The pelletized and sintered samples were further analyzed using SEM and electrochemical impedance spectroscopy (EIS). Notably, the precipitation methods yielded superior results, with the oxalate precipitation method achieving an ionic conductivity value of 9.8 x10-2 S/cm, which is 75% higher than the commercial sample.

Sarıboğa, V. (2022). Investigation of different efficient precipitation agents for the synthesis of superior oxide-ion conductor Ce0. 8Sm0. 2O1. 9 ceramic electrolytes for intermediate temperature-solid oxide fuel cells. Materials Today Communications, 33, 104463.

In this study, the superior oxide ion conductor 20% Sm-doped CeO2 (SDC20) structure was synthesized by using four different efficient precipitation methods to be used as electrolyte in solid oxide fuel cells: hydroxide, oxalate, and solvothermal and hexamethylenetetramine precipitation. In order to avoid unnecessary crystallite growth, the precipitated precursors were calcined at different temperatures specific to the method used. The powders were pelleted by uniaxial and cold isostatic press and then the pellets were sintered at 1200 and 1400 °C. Powder characterization were made by Thermogravimetric Analysis, Energy Dispersive X-Ray Analysis, X-Ray Diffraction and Scanning Electron Microscopy. The O2- ion conductivity of the pellets were determined by Electrochemical Impedance Spectroscopy in a static air environment. The O2- ion conductivity of the pellets were also compared with a commercial product. Solvothermal precipitated SDC20 stood out as the best method of the study by showing O2- ion conduction 65% superior to the commercial SDC20 sample with a conductivity of 9.2 × 10−2 Scm−1 at 800ºC.

Güçtaş, D., Sarıboğa, V., & Öksüzömer, M. F. (2021). Preparation of Sm0. 2Ce0. 8O1. 9 electrolytes via the chitosan templating method and investigation of the sintering behavior. Journal of Asian Ceramic Societies, 9(2), 487-497.

Sm0.2Ce0.8O1.9 electrolytes were prepared using a novel chitosan templating method. To examine the sintering kinetics of the materials, 5 minutes, 1 hour, and 6 hours of sintering processes were carried out at 1200, 1300, and 1400⁰C. The phase structure of the sintered samples was clarified by XRD analysis. The morphological structure was examined by SEM and the average grain sizes were calculated with the Linear Intercept Method. The dominant diffusion mechanism and grain growth activation energies during sintering were calculated for the SDC20 electrolytes synthesized by the chitosan templating method for the first time. In addition to the sintering study, the ionic conductivities of the samples were determined by electrochemical impedance spectroscopy. The maximum O2- conductivity value for the 1300–6 sample was found to be 0.052 S.cm−1. The study showed that the chitosan templating method is an effective way of synthesizing SDC20 materials.

Hydrogen Technologies (Hydrogen, Methanol, DME (Dimethyl Ether), Gasoline and Diesel Production)

Preparation and Characterization of Catalysts Showing High Efficiency and Stability in DME Synthesis from Synthesis Gas (2018-2020 TUBİTAK-1001 Project)

In this study, a number of catalysts were synthesized and characterized in order to convert syngas directly to chemical products such as methanol and dimethyl ether. Prepared catalysts were characterized by using Brunauer–Emmett–Teller (BET) surface area, X-ray diffraction (XRD), inductively coupled plasma-mass spectroscopy (ICP-MS), transmission electron microscopy (TEM), temperature-programmed desorption (CO2, NH3), temperature programmed reduction (TPR), diffuse reflectance infrared Fourier Transform (DRIFT) methods. Activity, selectivity and stability tests were performed with a High Pressure Plug Flow Reactor (PFR)-Gas Chromatography (GC) system.

Cu/ZnO/MgO (CZM), Cu/ZnO/CaO (CZCa), Cu/ZnO/Al2O3 (CZA), Cu/ZnO/B2O3 (CZB), Cu/ZnO/TiO2 (CZT) Cu/ZnO/ZrO2 (CZZ), Cu/ZnO/La2O3 (CZL), Cu/ZnO/Sm2O3 (CZS), Cu/ZnO/CeO2 (CZCe) catalysts were prepared and characterized by co-precipitation and EDTA-citrate technique.

Synthesis, Characterization and Improvement of Reaction Performances of Samarium and Lanthanum Based Catalysts with Different Morphologies for the Oxidative Coupling Reaction of Methane (2018-2020 TÜBİTAK-3001 Project)

In this study, some catalysts have been synthesized and characterized in order to convert methane directly into chemical products such as ethane and ethylene via oxidative coupling reaction (OCM). Prepared catalysts were characterized by Brunauer–Emmett–Teller (BET) surface area, inductively coupled plasma-mass spectroscopy (ICP-MS), X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (CO2, NH3 and O2-TPD) methods. Activity, selectivity and stability tests were performed with Microreactor-Gas Chromatography (Microreactor-GC) system. 

First, La2O3, Sm2O3 and La2O2CO3 catalysts have been synthesized and characterized in nano-particle, flower-like, nano-rod, nano-fiber and nano-sphere morphologies that can work at low temperatures (≤ 600°C). It was possible to synthesize the Sm2O2CO3 catalyst only in nano-rod morphology. The results obtained revealed that nanoparticle morphology can yield higher yields than other morphologies. In addition, it has been observed that Ln2O3 catalysts are easier to activate and provide higher yield than Ln2O2CO3 catalysts. It was determined that La2O3 also performed better than Sm2O3. As a result of the studies carried out by loading 4%, 8% and 12% Sr and Ba into La2O3 and Sm2O3 catalysts, it was determined that Sr additive gives better results than Ba additive and Sr additive increases both activity and selectivity. As a result of the characterizations, it was determined that the BET surface area, surface basicity and acidity, oxygen vacancy and active surface oxygen species concentration had an effect on C2 yield. As a result of the researches, it was found that La2O3, which contains 8% Sr by weight in nano-particle morphology, provides the highest C2 efficiency (15.1%) at 600°C. Additionally, it was determined that the 8Sr/La2O3-np catalyst showed a C2 yield quite close to the final target at 510°C, and it could yield 14% C2 yield after 50 hours.

Preparation and Characterization of Some Metal Oxides for Catalytic Processes by Urea-Nitrate Combustion Technique (2017-2018 BAP Project)

The metal oxides Al2O3, MgO, MgAl2O4, Sm2O3, La2O3 ve Gd2O3 that can be used for the partial oxidation of methane and the oxidative coupling reaction of methane are prepared by ureanitrate combustion method using 3 different urea / salt ratios and characterized by TG / DTA, XRD, BET and SEM analysis. It was determined that the structure yielded in the case of urea ratio 0,5 belongs to γAl2O3. When the ratio is 1 and 2, it was observed that the formation of α-Al2O3 occured. It was determined that cubic MgO structure was obtained at every urea ratio. If the ratio of urea is 2, it was observed that MgAl2O4 structure with high crystallinity occured and additionally some MgO phase seperation. When the urea ratio is 0.5, the phases observed were hexagonal La2O3, hexagonal La(OH)3 and hexagonal La2O2CO3. In addition to these phases, the monoclinic La2O2CO3 was observed when the ratio of urea increased to 1 and 2, respectively. When the urea ratio is 0.5, it was determined that cubic Sm2O3 and hexagonal Sm2O2CO3 phases were present. The increase of the urea ratio to 1 resulted in the formation of a mixture of cubic and monoclinic Sm2O3 in which Sm2O2CO3 disappeared. With the urea ratio of 2, only the presence of the monoclinic Sm2O3 phase was detected. The presence of cubic Gd2O3 was determined when the urea ratio was 0.5 and 1. When the ratio of urea is 2, it was observed that a mixture of cubic and monoclinic Gd2O3 formed. The urea ratios showed that the resulting compositions affected the phase contents, BET surface area, pore volume and shape. The results obtained show that all the structures can be synthesized without the need of calcination by the urea-nitrate combustion method.

Özdemir, H., Öksüzömer, M. F., & Gürkaynak, M. A. (2010). Preparation and characterization of Ni based catalysts for the catalytic partial oxidation of methane: Effect of support basicity on H2/CO ratio and carbon deposition. International journal of hydrogen energy, 35(22), 12147-12160. 

The catalytic partial oxidation of methane (CPOM) was studied on Ni based catalysts. Catalysts were prepared by wet impregnation method and characterized by using AAS, BET, XRD, HRTEM, TPR, TPO, Raman Spectroscopy and TPSR techniques. The prepared catalysts showed nearly 95% CH4 conversion and nearly 96% H2 selectivity under the flow of 157,500 (L kg−1 h−1) with the ratio of CH4/O2 = 2 by using air as an oxidant at 1 atm and 800 °C. Support basicity greatly influenced the H2/CO ratio and carbon deposition. It was found that the lowest carbon deposition occurred on Ni impregnated MgO catalyst. Considering the results, it was found that Ni/MgO catalyst with 10% Ni content would be the best catalyst amongst Ni/Al2O3, Ni/MgO/Al2O3, Ni/MgAl2O4 and Ni/Sorbacid for the CPOM only under more reductive conditions. Under optimum conditions, Ni/MgO showed poor performance and therefore Ni/Sorbacid would be the ideal catalyst because of its greater carbon resistance than the other catalysts.

Özdemi̇r, H., & Öksüzömer, M. F. (2020). Synthesis of Al2O3, MgO and MgAl2O4 by solution combustion method and investigation of performances in partial oxidation of methane. Powder technology, 359, 107-117.

Al2O3, MgO and MgAl2O4 nanocrystalline and mesoporous materials were prepared by simple solution combustion synthesis using urea and metal nitrates and the effect of metal nitrate/urea ratio was investigated. The metal oxides that were found suitable for catalytic purposes were tested in catalytic partial oxidation of methane (CPOM). It was observed that the oxidizer/fuel ratio could affect the structure phase, crystallinity and morphology of the synthesized materials. γ-Al2O3 was obtained when the equivalence ratio was 2, and at lower ratios, the obtained phase was α-Al2O3. The cubic MgO phase was obtained at each ratio but the material yield was low below the equivalence ratio of 4. Highly crystalline MgAl2O4 was obtained at fuel-rich conditions only. 10% (wt.) Ni loaded MgAl2O4-2 and MgO-4 showed high activity (>90% CH4 conversion) and product selectivity (>98% H2 and CO selectivity) at 800 °C under 157,500 l kg−1 h−1.

Solid Rocket Propellants (Metallic Fuels and Oxidation Catalysts)

Investigation of Different Types of Perovskite Catalyst Structures and Boron-M (M: Ca, Mg, Al, Si) Metal Fuels Prepared by Mechanical Alloying to Improve the Performance of Boron-Based Solid Rocket Fuels and Their Effects on Rocket Fuel Performance (2022-2024 TÜBİTAK 1001 Project)

Within the scope of the recently announced 10-point strategic goals of the Turkish Space Agency, in the 100th anniversary of our Republic, a hard landing on the Moon will be realized with a hybrid rocket that will be fired in close Earth orbit with international cooperation. In this context, it is necessary to focus on solid rocket propellants (SRP) in terms of R&D and high technology entrepreneurship, in order to reduce foreign dependency in aviation science and technologies, to increase international competitiveness, to create scientific and technological infrastructure and to develop all kinds of new technologies in our country. Conventionally, intensive studies are carried out in order to increase the combustion performance and adjust the burning rate in composite solid rocket propellants with AP-HTPB-Al structure.  In this context, boron is remarkable for our country, which is recommended for use in solid rocket propellants (SRP) in the world due to its combustion energy and has 73% of the reserves in the world.  However, problems such as the weak and unstable burning character of boron-containing solid rocket propellants and the need for a larger amount of oxidizer than conventional aluminum for complete oxidation arise. 

The aim of this study will be to increase the combustion rate with the unique SRP composition that will be developed to pave the way for the use of our national mine boron in rocket fuels within the framework of space research. For this purpose, it is aimed to improve the burning rate in a balanced way by increasing the production rate of oxidizer type for metal fuel oxidation by developing effective perovskite catalysts to be included in the composite SRP composition. In addition, it is thought that as a result of the amorphous alloying of boron with different metals (Ca,Si,Al,Mg) in order to increase the oxidation rate, the oxidation interest will increase, thus the composite SRP performance will increase.

In this study A and B sites modified La0.8A20.2B’xB’’1-xO3-δ (A2=Sr, Ca, B’ –B’’= Cr, Mn, Cu, Co, Ni, Fe, x=0,0.5, 1 perovskite structure catalyst, which are not investigated in the literature, will be added to the composite SRP composition.  The decomposition kinetics of the oxidizing component AP affected by this addition will be studied in detail. In addition, for the first time in the literature as rocket propellant component, boron will be alloyed with metals (M: Mg, Ca, Al, Si) with higher oxygen affinity by mechanical alloying to improve the combustion properties of boron. By increasing the oxygen affinity of the new amorphous boron alloys form obtained by mechanical alloying compared to pure boron, studies will be carried out to improve the burning rate of SRP. 

The final stage will be the determination of the appropriate combination of composition for SRP, with the catalyst structure and amorphous boron alloy form determined using the experimental design. TÜBİTAK-SAGE stated that they will assist us in all matters needed in the study, within their available resources. With the successful completion of the project, it is aimed to improve the performance of new boron and perovskite catalyst based propellant composition; to open the door to new projects for the stages of determining the real motor performance in the future, and to contribute to the long-range missiles and space travel studies of our country. The proposed project will be completed in 24 months and due to the heavy workload, there will be three graduate students in the project. In this context, another contribution of the project will be to train qualified researchers for our country.

In terms of the technological readiness level of the project (THS), it is planned that the technology will be reached from the applicability level (TRL3) to the prototype design and validation in the simulated environment (TRL6).