Browsing by Author "İnger, Erk"

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Citation Count: 0
Boric acid versus boron trioxide as catalysts for green energy source H2 production from sodium borohydride methanolysis
(2021) Demirci, Sahin; Ari, Betul; Sengel, Sultan B.; Inger, Erk; Sahiner, Nurettin; Airframe and Powerplant Maintenance
Here, boric acid (H3BO3) and its dewatered form, boron trioxide (B2O3) were tested as catalysts for hydrogen (H2) evolution in the methanolysis of sodium borohydride (NaBH4) in methanol. Parameters such as catalyst types and their amounts, NaBH4 concentration, and the reaction temperature affecting the hydrogen generation rate (HGR) were studied. It has been found that H3BO3 and B2O3 catalyzed methanolysis reaction of NaBH4 follow up first-order kinetics relative to the concentration of NaBH4. Furthermore, the conversion and activity of these catalysts were examined to determine their performance in ten consecutive use. Interestingly, H3BO3 and B2O3 have demonstrated superior catalytic performances in methanolysis of NaBH4 comparing to the studies published in literature with the activation energy of respectively 22.08 kJ.mol-1, and 23.30 kJ.mol-1 in H2 production. The HGR was calculated as 6481 mL.min-1.g-1 and 5163 mL.min-1.g-1 for H3BO3 and B2O3 catalyst, respectively for 50 mg catalyst at 298 K. These results are comparably better than most metal nanoparticle catalysts used for H2 production in addition to the naturally occurring boron-based environmentally friendliness of these materials.
BORLU ÇİMENTO
(Bilim ve Teknoloji, 2015) İnger, Erk; Airframe and Powerplant Maintenance
Çimento üretiminde klinkerine bor cevheri katkısı ile çimento üretiminde enerji tüketimi azaltılmakta, karbon dioksit salınımı düşürülmekte, yüksek mukavemetli ürün elde edilmekte ve çimentonun betonlaşması sürecinde oluşan hidrotasyon enerjisi minimize edilmektedir. Genel olarak, belit çimentosu sınıfında değerlendirilen borlu çimento, Portlant Çimentosu’na (PÇ) göre erken dayanıma katkısı azdır, ancak ileri yaşlarda yüksek mukavemet sağlamaktadır. Bunun aksine, yüksek belit çimentolarında (YBÇ), belit fazının reaktivitesi yüksek seviyelerde olup betona erken dayanım özelliği kazandırmaktadır. Borlu Çimento Standardı TS 13353 Yapımına esas olacak özellikler tespit edilerek onaylanmıştır. Ayrıca Bayındırlık Bakanlığı, borlu çimento birim fiyatları imalat ve ihzarat listeleri hazırlanmıştır. Borlu çimento üretiminde, ticari değeri düşük bor madeninin %17 B2O3 düşük tenörlü kolemanit cevheri kullanılmıştır. Ayrıca ürünün sanayi ölçeklerinde, Denizli Çimento Fabrikasında 3000 ton ve Isparta Çimento Fabrikasında üretilen 4000 ton Borlu çimento üretilmiştir. Özellikle borlu çimento beton karayolu çalışmaları, çok faydalı sonuçlar vermiştir.
Citation Count: 16
Catalytic activity of metal-free amine-modified dextran microgels in hydrogen release through methanolysis of NaBH₄
(Wiley, 2020) Inger, Erk; Sunol, Aydin K.; Sahiner, Nurettin; Airframe and Powerplant Maintenance
Polymeric microgels were prepared from dextran (Dex) by crosslinking linear natural polymer dextran with divinyl sulfone (DVS) with a surfactant-free emulsion technique resulting in high gravimetric yield of 78.5 +/- 5.3% with wide size distribution. Dex microgels were chemically modified, and then used as catalyst in the methanolysis of NaBH4 to produce H-2. The chemical modification of Dex microgel was done on epichlorohydrin (ECH)-reacted Dex microgels with ethylenediamine (EDA), diethylenetriamine (DETA), and triethylenetetraamine (TETA) in dimethylformamide (DMF) at 90 degrees C for 12 hours. The modified dextran-TETA microgels were protonated using treatment with hydrochloric acid (HCl) and m-Dex microgels-TETA-HCl was found to be a very efficient catalyst for methanolysis of NaBH4 to produce H-2. The effects of reaction temperature and NaBH4 concentration on H-2 generation rates were investigated and m-Dex microgels-TETA-HCl catalyst possessed excellent catalytic performances with 100% conversion and 80% activity at end of 10 consecutive uses and was highly re-generatable with simple HCl treatment. Interestingly, m-Dex microgels-TETA-HCl catalyst can catalyze NaBH4 methanolysis reaction in a mild temperature range 0 to 35 degrees C with Ea value of 30.72 kJ/mol and in subzero temperature range, -20 to 0 degrees C with Ea value of 32.87 kJ/mol, which is comparable with many catalysts reported in the literature.
Çoklu aşamalı aracı tasarımı
(2019) Alghadeer, Noor Hamzah Abbas; İnger, Erk; Airframe and Powerplant Maintenance
Bu tezde çok kademeli fırlatma aracı tasarladık. İlk aşamada, yaklaşık 42 km'ye ulaşmak için beş katı roket yakıtı ve bir sıvı itici fırlatma kullanılmıştır. İkinci aşamada, ağırlığı azaltmak için beş katı roket itici sistemden ayrılır. Daha sonra, bilimsel araştırma için, roket sistemindeki uydu, 925 km yüksekliğindeki düşük Dünya yörüngesine (LEO) geçmek üzere düşük sıvı yakıt ile gönderilir. Bu makalenin tasarımı, birkaç katı itici roketin etkisiyle kazanılan roketin hızı, roketin irtifa hesaplamaları ve roketin irtifası, katı roketlerin sayısı ve cinsine ve orbital hızına göre değişen rakımlarla gerçekleştirildi.
Citation Count: 0
Crosslinked polyethyleneimine-based structures in different morphologies as promising CO₂ adsorption systems: A comprehensive study
(Wiley, 2024) Demirci, Sahin; Inger, Erk; Bhethanabotla, Venkat; Sahiner, Nurettin; Airframe and Powerplant Maintenance
Although there are many studies on CO2 adsorption via PEI-modified carbon particles, metal-organic frameworks, zeolitic imidazolate frameworks, and silica-based porous structures, only a limited number of studies on solely cross-linked PEI-based structures. Here, the CO2 adsorption capacities of PEI-based microgels and cryogels were investigated. The effects of various parameters influencing the CO2 adsorption capacity of PEI-based structures, for example, crosslinker types, PEI types (branched [bPEI] or linear [lPEI]), adsorbent types (microgel or cryogel), chemical-modification including their complexes were examined. NaOH-treated glycerol diglycidyl ether (GDE) crosslinked lPEI microgels exhibited higher CO2 adsorption capacity among other microgels with 0.094 +/- 0.006 mmol CO2/g at 900 mm Hg, 25 degrees C with 2- and 7.5-fold increase upon pentaethylenehexamine (PEHA) modification and Ba(II) metal ion complexing, respectively. The CO2 adsorption capacity of bPEI and lPEI-based cryogels were compared and found that lPEI-GDE cryogels had higher adsorption capacity than bPEI-GDE cryogels with 0.188 +/- 0.01 mmol CO2/g at 900 mm Hg and 25 degrees C. The reuse studies revealed that NaOH-treated GDE crosslinked bPEI and lPEI microgels and cryogels showed promising potential, for example, after 10-times repeated use >50% CO2 adsorption capacity was retained. The results affirmed that PEI-based microgels and cryogels are encouraging materials for CO2 capture and reuse applications.
Citation Count: 13
PEI modifiednatural sands of Florida as catalysts for hydrogen production from sodium borohydride dehydrogenation in methanol
(Wiley-hindawi, 2021) Inger, Erk; Demirci, Sahin; Can, Mehmet; Sunol, Aydin K.; Philippidis, George; Sahiner, Nurettin; Airframe and Powerplant Maintenance
Sand samples from Tampa (T) and Panama (P) City beaches in Florida were used as catalysts for dehydrogenation of NaBH4 in methanol. T and P sand samples were sieved to <250, 250 to 500, and >500 mu m sizes, and the smallest fractions resulted in faster hydrogen generation rates (HGR), 565 +/- 18 and 482 +/- 24 mL H-2 (min.g of catalyst)(-1), respectively. After various base/acid treatments, HGR values of 705 +/- 51 and 690 +/- 47 mL H-2 (min g of catalyst)(-1) for HCl-treated T and P sand samples were attained, respectively. Next, T and P sand samples were modified with polyethyleneimine (PEI) that doubled the HGR values, 1344 +/- 103, and 1190 +/- 87 mL H-2 (min.g of catalyst)(-1) and increased similar to 8-fold, 4408 +/- 187, and 3879 +/- 169 mL H-2 (min g of catalyst)(-1), correspondingly after protonation (PEI+). The Ea values of T and P sand samples were calculated as 24.6 and 25.9 kJ/mol, and increased to 36.1, and 36.6 kJ/mol for T-PEI(+)and P-PEI(+)samples, respectively.
Citation Count: 35
Porous carbon particles as metal-free superior catalyst for hydrogen release from methanolysis of sodium borohydride
(Pergamon-elsevier Science Ltd, 2020) Demirci, Sahin; Yildiz, Mustafa; Inger, Erk; Sahiner, Nurettin; Airframe and Powerplant Maintenance
Carbon materials can be readily prepared from wood derivatives, monosaccharaides such as pentose/hexose and/or polysaccharides in addition to many starting materials by treatment of thermal, chemical and hydrothermal methods. Here, the porous carbon (PC) particles were prepared by removal of silica particles from previously prepared carbon-silica composites by hydrothermal and carbonization process from sucrose. Then, PC particles were modified with polyethyleneimine (PEI) to prepared amine functionalized PC-PEI particles and protonated with hydrochloric acid, PC-PEI+. Finally, these prepared carbon-based particles were used as catalyst for H-2 release from NaBH4 methanolysis and PC-PEI+ was found as the most effective catalyst at 25 degrees C with 4040 +/- 126 mL H-2. min(-1).g(-1) HGR value. The E s value of 23.9 kJ/mol in H-2 release reaction from NaBH4 methanolysis catalyzed by PC-PEI+ that is comparable and/or better than most of studies reported in literature. The activity% of PC-PEI+ catalyst was 72% after fifth consequential runs. Additionally, the regeneration ability of PC-PEI+ catalyst was also shown that after fifth regeneration process, there is only 5% decrease in activity%. (C) 2019 Elsevier Ltd. All rights reserved.