Destekleniş Metal Katalizör ile Sodyum Borohidrit Nabh4) Hidrolizinden Hidrojen Üretiminin İncelenmesi
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Date
2021
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Son yıllarda fosil yakıt kaynaklarının azalması ve çevre kirliliğinin artması alternatif enerji kaynaklarına olan ilgiyi artırmıştır. Alternatif enerji kaynakları arasında Hidrojen (H2) enerjisi, yüksek enerji yoğunluğu nedeniyle büyük önem taşımaktadır. H2 enerji kullanımındaki en önemli sorun temiz ve kolay üretim ve depolamadır. H2 üretim yöntemleri incelendiğinde, Sodyum bor hidrür (NaBH4) temelli H2 üretimi, güvenilir, verimli ve proton değişimli membran yakıt pillerine (PEMFC) kolayca entegre edilebilmesi nedeniyle büyük önem taşımaktadır. Bu tez çalışmasında, PEMFC uygulaması için NaBH4'ten H2 üretimi için çok duvarlı karbon nanotüp (MWCNT) ve çok duvarlı karbon nanotüp-grafen nano tabaka (MWCNT-GNP) destekli Palladyum-Rutenyum (Pd: Ru) bimetalik katalizörler geliştirilmiştir. Bu katalizörler mikrodalga sentez yöntemi ile hazırlanmıştır. Hazırlanan katalizörler Termogravimetrik Analizi (TGA), X-ışını kırınımı (XRD), transmisyon elektron mikroskobu (TEM) ve döngüsel voltametri (CV) analizleri ile karakterize edilmişlerdir. PdRu/MWCNT ve PdRu/MWCNT-GNP katalizörlerinin elektrokimyasal yüzey alanı (ECSA) sırasıyla 12.36 m2/g ve 20.74 m2/g olarak belirlenmiştir. Analizler sonucunda PdRu/MWCNT katalizörünün % 34 olarak düşük bir ECSA kaybı gösterdiği saptanmıştır. Sentezlenen katalizörler, NaBH4'ün kimyasal hidrolizinden H2 üretimini araştırmak için farklı koşullarda test edilmiştir. PdRu/MWCNT ve PdRu/MWCNT-GNP katalizörleri için yapılan kinetik çalışmalar sonucunda aktivasyon enerjileri sırasıyla 18.90 kJ/mol ve 22.33 kJ/mol olarak bulunmuştur. PdRu/MWCNT-GNP katalizörü ile yapılan yeniden kullanılabilirlik deneyleri, GDL destekli katalizörlerin verimliliğini toz katalizörden daha iyi koruduğunu göstermiştir. 65 oC'de gerçekleştirilen PEMFC testleri sonucunda katı NaBH4 temelli H2 üretim sisteminin ve saf H2'nin benzer performansa sahip olduğunu belirlenmiştir. Elde edilen sonuçlar, PdRu/MWCNT-GNP bimetalik katalizörün, PEMFC uygulaması için NaBH4'ten H2 üretmek için uygun bir katalizör olduğunu göstermektedir.
In recent years, the decrease in fossil fuel resources and the increase in environmental pollution has increased the interest in alternative energy sources. Among alternative energy sources, Hydrogen (H2) energy is of great importance due to its high energy density. The most important benefit in using H2 energy is the clean and easy produc-tion and storage. When H2 production methods are examined, sodium borohydride (NaBH4) based H2 production is of great significance, and the particular reason for this circumstance is that it is renewable, reliable, and efficient and can easily be inte-grated into proton exchange membrane fuel cells (PEMFC). In this thesis, Palladium-Ruthenium (Pd:Ru) bimetallic catalyst supported on Multi-walled Carbon Nanotubes (MWCNT) and Multiwall Carbon Nanotube Doped Gra-phene Nanoplatelets (MWCNT-GNP) has been developed for H2 production from hydrolysis of NaBH4 for PEMFC application. These catalysts were synthesized by the microwave assisted synthesis approach. The prepared catalysts were characterized by Thermogravimetric Analysis (TGA), X-ray diffraction (XRD), Transmission Elec-tron Microscopy (TEM) and cyclic voltammetry analysis (CV). The electrochemical surface area (ECSA) of the PdRu/MWCNT and PdRu/MWCNT-GNP catalysts were determined as 12.36 m2/g and 20.74 m2/g, respectively. PdRu/MWCNT showed a faintly lower ECSA loss as 34%. The catalysts were tested to investigate the H2 production from the chemical hydrol-ysis of NaBH4. Hydrolysis reactions were examined under various experimental con-ditions. Kinetic studies were executed for PdRu/MWCNT and PdRu/MWCNT-GNP, and the activation energies were found as 18.90 kJ/mol and 22.33 kJ/mol, re-spectively. The reusability experiments with PdRu/MWCNT-GNP revealed that GDL supported catalysts maintained its 89 % efficiency better than the powder cata-lyst. The PEMFC test performed at 65oC showed that the H2 generation system based on solid NaBH4 hydrolysis and pure H2 have similar performance. The obtained results showed that the PdRu/MWCNT-GNP bimetallic catalyst is an appropriate catalyst to produce H2 from hydrolysis of NaBH4 for PEMFC application.
In recent years, the decrease in fossil fuel resources and the increase in environmental pollution has increased the interest in alternative energy sources. Among alternative energy sources, Hydrogen (H2) energy is of great importance due to its high energy density. The most important benefit in using H2 energy is the clean and easy produc-tion and storage. When H2 production methods are examined, sodium borohydride (NaBH4) based H2 production is of great significance, and the particular reason for this circumstance is that it is renewable, reliable, and efficient and can easily be inte-grated into proton exchange membrane fuel cells (PEMFC). In this thesis, Palladium-Ruthenium (Pd:Ru) bimetallic catalyst supported on Multi-walled Carbon Nanotubes (MWCNT) and Multiwall Carbon Nanotube Doped Gra-phene Nanoplatelets (MWCNT-GNP) has been developed for H2 production from hydrolysis of NaBH4 for PEMFC application. These catalysts were synthesized by the microwave assisted synthesis approach. The prepared catalysts were characterized by Thermogravimetric Analysis (TGA), X-ray diffraction (XRD), Transmission Elec-tron Microscopy (TEM) and cyclic voltammetry analysis (CV). The electrochemical surface area (ECSA) of the PdRu/MWCNT and PdRu/MWCNT-GNP catalysts were determined as 12.36 m2/g and 20.74 m2/g, respectively. PdRu/MWCNT showed a faintly lower ECSA loss as 34%. The catalysts were tested to investigate the H2 production from the chemical hydrol-ysis of NaBH4. Hydrolysis reactions were examined under various experimental con-ditions. Kinetic studies were executed for PdRu/MWCNT and PdRu/MWCNT-GNP, and the activation energies were found as 18.90 kJ/mol and 22.33 kJ/mol, re-spectively. The reusability experiments with PdRu/MWCNT-GNP revealed that GDL supported catalysts maintained its 89 % efficiency better than the powder cata-lyst. The PEMFC test performed at 65oC showed that the H2 generation system based on solid NaBH4 hydrolysis and pure H2 have similar performance. The obtained results showed that the PdRu/MWCNT-GNP bimetallic catalyst is an appropriate catalyst to produce H2 from hydrolysis of NaBH4 for PEMFC application.
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Kimya Mühendisliği, Chemical Engineering, Hidroliz, Hydrolysis
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