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Sodium borohydride hydrolysis and regeneration: Simulation, economics, and forecasting
(Elsevier BV, 2025-08) Yavuz Kirim
In this study, the hydrolysis and regeneration process of NaBH4 is simulated using Aspen Plus software. Using three different kinetics including zero-order, first-order and LHHW, H2 production quantities and NaBH4 production by regeneration from NaBO2 are compared. LHHW kinetic model has the highest amount H2 with 198.83 kmol/h. Techno-economic analysis is also carried out for three reaction kinetics using different economic metrics. NPV of all the kinetic models result in infeasible due to negative NPV which is -$12580.73, -$1642.51, and $-15478.66, respectively. Moreover, econometric analysis is conducted on the Mg price and production using R software for through five years onwards using ARIMA model. ARIMA (1,0,3) model is the most appropriate time series model for Mg price forecasting whereas ARIMA (0,1,0) are available time series model for Mg production. The ARIMA (0,1,0) is also denoted as random walk model means that Mg production is not forecasted five years onwards.
Optimization study of a hybrid renewable energy system for co-production of electricity and heat at a hydrogen refuelling station
(Elsevier BV, 2025-07) Berna Burcu Kalyoncu; Yavuz Kırım; Hasan Sadikoglu
The purpose of this study is to identify the best hybrid renewable energy system (HRES) configuration for a hydrogen refuelling station located in Schleswig, Holstein. Techno-economic analysis and configuration simulations are performed using the Hybrid Optimization of Multiple Energy Resources (HOMER) Pro program. Initially, HRES powered by photovoltaics (PV) and two different wind turbines (WT) are proposed, achieving 100 % renewable fraction. Alternative configurations include a thermal load controller (TLC), a boiler and a micro gas turbine (MGT). The renewable fractions of these configurations are reduced to over 40 %. The best system configuration comprises PV panels, XANT L-36 WT, Vestas V47 WT, hydrogen storage tank, electrolyser, battery, TLC, boiler, and MGT, with net present cost (NPC) of $6.28 million. Furthermore, four regression models are utilized for the econometric evaluation of global green hydrogen production in the R programming language (R). The ridge regression (RR) model demonstrates the best performance, providing a good fit for our data.
Enhanced hydrogen production from sucrose-derived carbon quantum dots-supported Ru catalysts: A comparative study of KBH4 and NaBH4 hydrolysis
(Elsevier BV, 2025-12) Erhan Onat; Mehmet Sait İzgi; Ömer Şahin; Selma Ekinci
Despite increasing interest in borohydride hydrolysis for hydrogen generation, limited studies have explored carbon quantum dots (CQDs) derived from low-cost, renewable sources such as sucrose as catalyst supports. In this study, sucrose-derived CQDs were synthesized via a green hydrothermal method and employed as a support material for Ru catalysts. A novel hydrogen potential catalytic activity (HPCA) metric was introduced to compare the performance of Ru@CQDs in the hydrolysis of sodium borohydride (SBH) and potassium borohydride (PBH), addressing the lack of normalized efficiency metrics across different hydrogen sources. The ideal conditions for each hydrolysis reaction were established based on the hydrogen generation rate (HGR) after studying various catalyst characteristics using UV–Vis, UV-PL, TEM, and FT-IR analyses. The HGR values using 4 % NaBH4 and 4 % KBH4 were 167,588 and 122,527 mL g−1 min−1, respectively. However, the hydrogen potential catalytic activity metrics (HPCA), calculated based on the hydrogen content of the sources, were 1.551,741 mL g−1 min−1 and 1.655,770 mL g−1 min−1 for NaBH4 and KBH4 hydrolysis, respectively. This indicates that the rate of hydrogen production during KBH4 hydrolysis is higher than that during NaBH4 hydrolysis. For each hydrolysis reaction, the catalyst's turnover frequency (TOF) was also determined to assess its effectiveness: 924.8 mol H2.mol. Ru−1.min−1 for NaBH4 hydrolysis and 573.3 mol H2.mol Ru−1.min−1 for KBH4 hydrolysis. Additionally, the experimental data on the kinetics and activation energy of the hydrolysis processes, as well as the catalyst's reusability, were analyzed.
Facile fabrication of carbon quantum dot-based CdS and Co-doped CdS nanocomposites as effective sensitizers for solar cell applications: a hydrothermal synthesis approach
(Springer Science and Business Media LLC, 2025-05) Orhan Baytar; Sabit Horoz; Ömer Şahin; Sinan Kutluay
The development of efficient and sustainable materials for solar energy conversion remains a key challenge in renewable energy research. Cadmium sulfide (CdS) nanoparticles are widely used as sensitizers in solar cells due to their favourable optoelectronic properties. However, their efficiency is often limited by charge recombination and poor electron transport. To overcome these limitations, this study explores the incorporation of carbon quantum dots (CQDs) and cobalt (Co) doping into CdS nanocomposites (NCs) to enhance their photovoltaic performance. CQDs, synthesized from mulberry molasses via a hydrothermal method, were incorporated into CdS to improve charge separation, while Co doping was employed to reduce recombination losses. The structural and electronic properties of the synthesized CdS/CQD and Co-doped CdS/CQD NCs were thoroughly characterized using Fourier transform infrared spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), transmission electron microscopy (TEM) and ultraviolet-visible (UV-Vis) spectroscopy. The photovoltaic performance was evaluated by current-density-voltage (J-V) measurements, revealing that the Co-doped CdS/CQD NCs exhibited superior efficiency (2.21%) compared to CdS/CQD (2.17%). The observed improvement is attributed to enhanced electron injection and reduced recombination due to Co doping. These results highlight the potential of Co-doped CdS/CQD NCs as effective sensitizers in solar cells, offering a promising strategy for the advancement of sustainable photovoltaic technologies.
Valorization of spent coffee grounds: a multi-solvent extraction approach and blending with waste cooking oil for sustainable biodiesel production
(Informa UK Limited, 2025-04-22) Ramiz Rafil Al-Samaraae; Abdulaziz Atabani; Ismail Bogrekci; Muhamed Raşit Atelge; Tülin Avcı Hansu; Mustafa Kaya; Hilal Demir Kıvrak; Yalçın Şevki Yıldız; Selahaddin Orhan Akansu; Sebahattin Ünalan; Pinar Demircioglu
A worldwide waste stream, spent coffee grounds (SCG), presents serious environmental challenges because of landfill disposal and methane emissions. In this work, the valorization of SCG through oil extraction and biodiesel synthesis has been investigated. Hexane, a non-polar solvent, achieved the highest spent coffee grounds oil (SCGO) yield of 18.73 ± 2.31% (dry weight basis). Non-polar solvents usually produce lower free fatty acid (FFA) content than polar solvents. For instance, hexane extracted SCGO with an acid value of 7.85 mg KOH/g, much below ethanol (16.20 mg KOH/g). The direct alkaline transesterification via blending SCGO with low FFA WCO is a creative way to lower the FFA of SCGO. This reduced production costs, energy requirement and catalyst consumption as it eliminates the need for the 2-step esterification-transesterification process. A biodiesel yield of 99% was achieved with 90%WCO:10%SCGO blend. The biodiesel quality was validated via GC-MS, FT-IR, NMR and TGA analyses. Results indicated that SCGO is a promising biodiesel feedstock when blending with WCO. This helps make the economy more sustainable and circular by reducing reliance on fossil fuels and waste generation. This study falls well within the UN Sustainable Development Goals (SDGs) such as Affordable and Clean Energy (SDG7) and Climate Action (SDG13)
Green synthesis of highly efficient and stable Ni@CQD nanoparticles: Experimental and theoretical approach for hydrogen production from dimethyl aminborane and sodium borohydride hydrolysis
(Elsevier BV, 2025-10) Mehmet Sait Izgi; Ömer Şahin; Sultan Faal; Fatih Ahmet Celik; Erhan Onat; Ezman Karabulut
In this study, four different catalysts (Ni(0), Ni@Urea, Ni@DOT, Ni@MOF-DOT) were synthesized. The first two of these were synthesized by the impregnation method, while the last two were obtained using the hydrothermal method. Hydrogen (H2) efficiency of catalyses were investigated by hydrolysing sodium borohydride (SBH) and dimethylamine borane (DMAB) hydrogen sources. The HGR values obtained for SBH and DMAB hydrolysis of the best catalysis Ni@MOF-DOT were determined to be 1423 and 642 (mL/min.g.cat), and the TOF values were determined to be 191/hour and 78.6/hour, respectively. Transmission Electron Microscopy (TEM), Energy-dispersive X-ray spectroscopy (EDS), nitrogen adsorption/desorption, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Inductively coupled plasma optical emission spectroscopy (ICP-OES) and X-ray photoelectron spectroscopy (XPS) analyses were used for the characterization study of Ni@CQDs nano-catalyst. In kinetic analyses driven by Arrhenius and Eyring-Polanyi equations, the catalyst in the hydrolysing of DMAB has lower activation parameters while the catalysts have showed stability over six reusability cycles in both hydrogen sources. Also, the average particle size of the (Ni@DOT-MOF) nano catalyst is about 4.6 nm and the presence of Carbon (C), oxygen (O), nitrogen (N) and Ni (Ni) atoms in its structure is confirmed by XPS and ICP analyses. The high density of 2P1/2 and 2P3/2 spin states of Ni atoms in the Ni@MOF-DOT catalyst creates Lewis acid regions that increase the catalytic activity. The experimental results were supported by Molecular Dynamics (MD) findings based on extended tight-binding density functional theory (GFN1-xTB)
Applications of Environmentally Friendly Metal Oxides as PEM Fuel Cell Cathode Catalysts
(Springer Science and Business Media LLC, 2025-04-10) Orhan Baytar; Ömer Şahin; Abdurrahman Akdag; Gurbet Canpolat; Arzu Ekinci
For the first time, this study investigated the behaviors of CuO and FeO metal oxides synthesized from bean shell extract using an environmentally friendly green synthesis method at varying cell temperatures in PEMFCs according to the amount of Pt used. Analyzed techniques such as XRD, SEM–EDX, TEM, and XPS were used to ascertain the structural and morphological characteristics of the produced catalysts. The performance of the catalysts was evaluated based on the voltage-current density values obtained from PEMFCs at different cell temperatures and increased at higher cell temperatures.At a cell temperature of 70 °C, the Pt-FeO/C and Pt-CuO/C catalysts exhibited higher power values than the Pt/FeO-C and Pt/CuO-C catalysts, containing only half the amount per unit area. The power density values for catalysts were tested as follows: 3380 mW/cm2mgPt for Pt-FeO/C, 1697 mW/cm2mgPt for Pt-CuO/C, 919 mW/cm2mgPt for Pt/FeO-C, and 1264 mW/cm2mgPt for Pt/CuO-C, and these values were determined to be higher than the values measured using the Pt/C (431 mW/cm2mgPt) catalyst. According to the measured current density-power density values, It was determined that the performances of the catalysts were Pt/FeO-C > Pt-CuO/C > Pt/CuO-C > Pt-FeO/C.
Effective and environmentally friendly Co nanocatalyst on sodium borohydride hydrolysis in different solvents
(Elsevier BV, 2025-01) Erhan Onat; Selma Ekinci; Ömer Şahin; Mehmet Sait İzgi
This study investigates the development and performance of a cobalt (Co) nanocatalyst supported by carbon quantum dots (CQDs) for hydrogen production via sodium borohydride (NaBH₄) hydrolysis. The CQDs were synthesized using a hydrothermal method from caffeine and subsequently used to support the cobalt catalyst. The structure and properties of the synthesized catalyst were characterized using techniques such as X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and energy dispersive spectroscopy (EDX). The catalytic performance was evaluated in various solvents, with the highest hydrogen production rate observed in ethanol. The optimal conditions for Co@CQDs catalyst synthesis were identified as an 8-h hydrothermal treatment with a 3 mmol metal loading. The catalyst demonstrated excellent reusability, maintaining 100% hydrogen production efficiency after seven cycles. The activation energy for the hydrolysis reaction was found to be lower for catalysts synthesized in ethanol (25.48 kJ mol−1) compared to those synthesized in water (35.57 kJ mol−1), indicating enhanced catalytic activity. Under optimum conditions, the hydrolysis reaction in the presence of Co@CQDs (water) catalyst produced 23753 mL min−1 g−1 of hydrogen, while the hydrolysis reaction in the presence of Co@CQDs (ethanol) catalyst produced 28751 mL min−1 g−1. This study highlights the potential of CQDs-supported Co nanocatalysts for efficient and sustainable hydrogen production.
Eco-friendly biosynthesized silver, copper, and nickel nanoparticles mediated Rheum ribes: Assessment of their cytotoxicity and antimicrobial activity
(Elsevier BV, 2025-02) Bahri Gür; Mustafa Cengiz; Canan Vejselova Sezer; Orhan Baytar; Ömer Şahin; Adnan Ayhanci; Hatice Mehtap Kutlu
Background: The green synthesis of metallic nanoparticles has recently become a research area of increasing interest due to their potential applications in nanomedicine. Aim of study: This study aimed to investigate, for the first time, the anticancer properties of silver nanoparticles (Ag-NPs), copper oxide nanoparticles (CuO-NPs), and nickel oxide nanoparticles (NiO-NPs) on A549 and Beas-2B cell lines, as well as their antibacterial efficacy against Escherichia coli and Staphylococcus aureus strains, synthesized through a green synthesis approach utilizing Rheum ribes plant extract. Methodology: The current study introduces a sustainable and environmentally friendly method for the biosynthesis of Ag-NPs, CuO-NPs, and NiO-NPs utilizing the aqueous extract of Rhubarb (Rheum ribes). The spectroscopic and morphological properties of the Ag-NPs, CuO-NPs, and NiO-NPs obtained from the Rheum ribes extract were confirmed using different analytical techniques. Results: The Ag-NPs, CuO-NPs, and NiO-NPs exhibited different morphology with a size of about 7.90, 12.0, and 12.63 nm, respectively, and were free of impurities and highly stable particles. In addition, the NPs were further investigated for their anticancer and antibacterial properties. The anticancer effects of the NPs were assessed using the MTT assay and confocal microscopy in non-small cell lung cancer (A549) and healthy lung (Beas-2B) cells. The study results demonstrated that Ag-NPs, CuO-NPs, and NiO-NPs had cytotoxic effects on A549 cells that were concentration-based, having IC50 values of 4.16, 21.28, and 37.68 μg/mL, in that order. Additionally, it was observed that the above-mentioned NPs exhibited strong activity against bacteria. Conclusions: The nanoparticles derived from Rheum ribes extract appear to hold great potential as a class of nano-biomaterials intended for usage in biological fields.
Techno-economic and hybrid energy system analyses of hazelnut shell gasification based on geographical information system
(Elsevier Ltd, 2025) Kirim, Yavuz; Yıldız, Ertuğrul; Sadikoglu, Hasan; Melikoglu, Mehmet
In this study, electricity generation from hazelnut shells via gasification is studied in detail using Aspen Plus and economic analysis of the hazelnut gasification is thoroughly investigated. Novel to this study, hybrid energy generation potential of hazelnut shell gasification with different alternatives including PV are explored and H2 production from hazelnut shell is simulated in Aspen Plus. Mass flow of main outlet products (CO and H2) is 1103.43 kg/hr and 81.62 kg/hr, respectively. GIS is used to define the optimum area for the proposed hazelnut shell gasification plant. The production of syngas obtained from Aspen Plus simulation is estimated as 21,286,234 Nm3/yr, NPC and IRR values of the proposed gasification plant using method of time value of money are calculated as $106,673 and 28 %, respectively. NPC and COE of hybrid renewable energy system including battery storage are calculated as $6.87 M and $0.715, respectively. © 2024 Elsevier Ltd
Synthesis and properties of Schiff base Fe(II) complex
(2019) Kılınç, Dilek; Şahin, Ömer; Horoz, Sabit
In our current study, Fe (II) complex with 4-4ʹ-methylene bis (2,6-diethyl) aniline-3,5-di-tert-butylsalisilaldimine (HL1) ligand was synthesized by chemical method and the synthesized Fe (II) complex with HL1 ligand was named as Fe(L1)2 complex. Structural, morphological, electronic absorption and photovoltaic properties of Fe(L1)2 complex were characterized by x-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscope, electronic absorption, and current density (J)–voltage (V) measurements, respectively. The obtained result from the J-V measurement shows that Fe(L1)2 complex synthesized by the chemical method can be used as a promising sensitizer for a dye-sensitized solar cell.
Equilibrium, kinetic and thermodynamic studies for dynamic adsorption of benzene in gas phase onto activated carbon produced from elaeagnus angustifolia seeds
(Elsevier, 2019) Kutluay, Sinan; Baytar, Orhan; Şahin, Ömer
Adsorption of pollutants onto activated carbon is very important in air purification systems. In this study, the dynamic adsorption of benzene in gas phase onto activated carbon which was produced from the elaeagnus angustifolia seeds, was investigated using a laboratory-scale continuous flow fixed-bed reactor system, under atmospheric pressure. The effects of the adsorption conditions such as activated carbon particle size (180–500 μm), nitrogen (N2) gas flow rate (0.050–0.120 L min−1) as the benzene in gas phase carrier, amount of activated carbon (0.10–0.75 g), concentration of benzene in gas phase at the inlet (9.95–14.85 ppm) and the adsorption temperature (293–323 K) on both the adsorption capacity and the adsorption efficiency were examined. Adsorption efficiency was achieved up to 100% under various adsorption conditions. Adsorption kinetics data were analyzed by using the Pseudo-First Order and Pseudo-Second Order kinetic models. Langmuir, Freundlich and Dubinin-Radushkevich models were used for the analysis of adsorption isotherms. The results showed that the Langmuir isotherm and Pseudo-Second Order models described the experimental data better when compared to other models. The maximum monolayer adsorption capacity (qmax) of activated carbon was determined to be 99.8 mg g−1 for 303 K. Thermodynamic analyzes indicated that the adsorption process of benzene in gas phase onto activated carbon was spontaneous (ΔG°<0), exothermic (ΔH°<0) and physical (ΔH°<20 kJ mol−1).
Fabrication of Pure Sb2S3 and Fe (2.5%): Sb2S3 thin films and ınvestigation their properties
(2019) Nar, Seren; Şahin, Ömer; Horoz, Sabit
Pure Sb2S3 and Fe (2.5%): Sb2S3 thin films were synthesized on Zn2SnO4 coated with FTO conductive glasses using chemical bath deposition (CBD) technique. The X-ray diffraction (XRD) patterns obtained show that both thin films have an orthorhombic structure. Although the crystal structure of the two thin films was the same, the crystalline size of Fe (2.5%): Sb2S3 thin film (51.15 nm) was found to be smaller than that of pure Sb2S3 (52.89 nm). The effect of Fe doped metal on crystal size of Sb2S3 was observed with this result. Another important observation is that the energy band gap of Fe (2.5%): Sb2S3 thin film (2.00 eV) is larger than that of pure Sb2S3 (1.89 eV). The photovoltaic properties of the synthesized thin films were examined by applying both incident photon-to-current efficiency (IPCE) and current density (J)–voltage (V) measurements. The obtained IPCE(%) values at 600 nm for pure Sb2S3 and Fe (2.5%): Sb2S3 thin films are 30.29 and 49.06, respectively. Using the J–V curves, the calculated η (%) values for pure Sb2S3 and Fe (2.5%): Sb2S3 thin films are 3.95 and 5.44, respectively. Based on the data obtained from both measurements, it was observed that the Fe dopant significantly enhance the performance of the Sb2S3-based solar cell devices.
Catalytic activity of cobalt-boron-fluoride particles with different solvent mediums on sodium borohydride hydrolysis for hydrogen generation
(Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2019) İzgi, Mehmet Sait; Şahin, Ömer; Baytar, Orhan; Saka, Cafer
Catalysts prepared in a different solvent medium have different activities because of its different acidity, basicity and viscosity properties. The synthesis mechanism of cobalt-boron-fluoride in water, propanol and ethanol solvents was evaluated. Characterization studies of cobalt-boron-fluoride catalyst were performed with Brunauer-Emmett-Teller surface area, X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy- energy dispersive x-ray spectroscopy measurements. The effects of sodium borohydride (SB), and temperature on the SB hydrolysis reaction with the catalyst samples were studied. The maximum hydrogen generation rate (HGRs) of the cobalt-boron (ethanol solvent) and cobalt-boron-fluoride (ethanol solvent) catalysts were 1942 and 4533 mlmin−1g−1, respectively. The activation energy was 32.45 kJ mol−1.
Production of metal-free catalyst from defatted spent coffee ground for hydrogen generation by sodium borohyride methanolysis
(elsevier, 27.08.2019)
In the present study, defatted spent coffee ground (DSCG) treated with different acids was used as a metal-free catalyst for the first time. The aim of undertaken work is to demonstrate that DSCG can be used as a green catalyst to produce hydrogen through methanolysis of sodium borohydride. To produce hydrogen by the sodium borohydride methanolysis (NaBH4), DSCG was pretreated with different acids (HNO3, CH3COOH, HCl). According to the superior acid performance, acetic acid was selected and then different concentrations of the chosen acid were evaluated (1M, 3M, 5M, and 7M). Subsewuently, different temperatures (200, 300, 400 and 500 °C) and burning times (30, 45, 60 and 90 min) for the optimization of DSCG-catalyst were tested. The experiments with the use of CH3COOH treated DSCG-catalyst reveal that the optimal acid concentration was 1M CH3COOH and the burning temperatures and time were 300 °C and 60 min, respectively. FTIR, SEM, ICP-MS and CHNS elemental analysis were carried out for a through characterization of the catalyst samples. In this study, the experiments were carried out with 10 ml methanol solution contained 0.025 g NaBH4 with 0.1 g catalyst at 30 °C unless otherwise stated. The effect of NaBH4 concentration was investigated with use of 1%, 2.5%, 5%, and 7.5% NaBH4, while the influence of catalyst concentration was discovered with the use of 0.05, 0.1, 0.15, and 0.25 g catalyst. Different temperatures were chosen (30, 40, 50 and 60 °C) to explore the hydrogen production performance of the catalyst. In addition, the maximum hydrogen production rate through methanolysis reaction of NaBH4 by this catalyst was found to be 3171.4 mL min−1gcat−1. Also, the activation energy was determined to be 25.23 kJ mol−1.
Determination of Nucleation Kinetics of Ammonium Biborate Tetrahydrate
(2014) Demir, Halil
The ammonium biborate tetrahydrate was synthesized by stoichiometric incorporation of boric acid and ammonium hydroxide in aqueous solution and the effects of supersaturation, temperature, pH of solution, cooling rate and presence of impurities upon the metastable zone width (MZW) were investigated. The MZW of ammonium biborate tetrahydrate aqueous solution was increased with increasing concentration of impurities. The saturation temperature was increased in the presence of Ca (II) ion and decreased in the presence of Pb (II) and Mg (II) ions.
Hydrogen Generation from Sodium Borohydride Hydrolysis with a Cu–Co-Based Catalyst: A Kinetic Study
(Taylor and francis, 2015) Demir, Halil
In the present work, Cu–Co-supported catalysts were tested for hydrogen generation from the hydrolysis reaction of an alkaline sodium borohydride solution. Cu–Co catalysts were prepared by the chemical reduction with NaBH4 and characterized with scanning electron microscope. The effect of Cu–Co ratio was investigated. The results suggested that the optimal mixture percentage of Cu–Co catalyst was 60:40; excessive Cu resulted in poor catalytic activity. The reactions were carried out at temperatures of 20, 30, 40, and 50°C. The experimental data was fitted to the nth-order kinetic models. The results indicate that the nth-order model gives a reasonable description of the hydrogen generation rate over all of the temperature range. The activation energy and pre-exponential factor of the nth-order reaction model were obtained as 42.66 kJ mol−1 and 1.21 × 104, respectively.
Preparation and Characterization of Activated Carbon from Microwave and Conventional Heated Almond Shells Using Phosphoric Acid Activation
(Analytical Letters, 2019) İZGİ, Mehmet Sait; Gamze Saraçoğlu; Baytar, Orhan; Şahin, Ömer; Saka, Cafer
Activated carbon production from almond shells using phosphoric acid activation agent was achieved by applying both conventional heating and microwave heating in succession. The morphology and surface properties of activated carbon were studied using thermogravimetric and differential gravimetric analysis, Fourier-transform infrared spectroscopy, scanning electron microscopy, and Brunauer–Emmett–Teller analysis. A surface area of 1128 m2/g was achieved by optimizing the microwave power (500 W), microwave application time (15 minutes), conventional heating time (45 minutes), conventional heating temperature (500 °C), and the phosphoric acid:sample ratio (0.7:1). An adsorption capacity of methylene blue of 148 mg/g and an iodine value of 791 mg/g was obtained for the prepared activated carbon.
γ-Al2O3 supported/Co-Cr-B catalyst for hydrogen evolution via NH3BH3 hydrolysis
(Materials and Manufacturing Processes, 2019) İZGİ, Mehmet Sait; Saka, Cafer; Şahin, Ömer
This assay investigates the Co-Cr-B catalyst effect supported on γ-Al2O3 to produce hydrogen (HG) from ammonia-borane hydrolysis (ABH). For characterization of this catalyst, SEM-EDX, XRD, FTIR and BET surface area analysis were performed. The maximum hydrogen generation rate (HGR) with this catalyst used for the ABH was 3260 ml min−1 g−1catalyst. The recyclability tests for the Co-Cr-B/γ-AlO3 catalyst on the ABH have maintained an activity of 68% even after four hydrolysis treatments. Also, the activation energy (Ea) obtained using the Co-Cr-B catalyst supported on γ-AlO3 for the ABH was 56.06 kJ/mol.
Novel activated carbon supported trimetallic PdCoAg nanoparticles as efficient catalysts for the hydrolytic dehydrogenation of ammonia borane
(Journal of Hydrogen Energy, 2019) Mehmet Sait İZGİ
Activated carbon (AC) supported palladium, cobalt and silver nanoparticle (PdCoAg/AC) catalysts were prepared by in situ reduction of sodium borohydride (NaBH4) and characterized by various techniques such as X-ray diffraction (XRD), scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDX), Transmission electron microscopy (TEM) and X-ray Photoelectron Spectroscopy (XPS). The PdCoAg/AC catalyst is active in the hydrolysis of ammonia-borane (AB) even at low temperatures. Compared with mono- (Pd) and bi-metallic (PdCo) nanoparticles, this trimetallic (PdCoAg) structure showed greatly increased catalytic activity for AB hydrolysis. Their hydrolysis completion time was 50 s. This study also included full experimental details of kinetic data to determine the activation parameters (Ea, and ) for the rate law and the catalytic hydrolysis of AB. In addition, the PdCoAg/AC catalysts had favorable catalytic activity also after seven runs. Hydrogen generation rate (HG), Ea, and were obtained at 25 °C as 4666.66 mL min−1g−1 (2 mmol AB and 50 mg PdCoAg/AC), 26.836 kJ mol-1, 29.416 kJ mol−1and –108.42 J mol−1K−1, respectively. In addition, the study showed that Pd0.6Co0.2CAg0.2/AC (Pd:Co:Ag atomic ratio = 6:2:2) showed the total turnover frequency (TOF) value of 6624 h−1. These results demonstrate that the PdCoAg/AC catalyst is a promising alternative in search of the practical application of AB as a hydrogen storage material for fuel cell applications.

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