$Al_2O_3$/Spirulina Platensis Destekli Co Katalizörü Varlığında Sodyum Borhidrürün Metanolizinden Hidrojen Üretiminin İncelenmesi

Bu çalışmada, $Al_2O_3$/Spirulina Platensis mikroalg karışımı ilk kez destek maddesi olarak kullanılmıştır. Buradaki amaç yenilenebilir enerji kaynağı olan hidrojenin üretiminde kullanılan katalizörlerin etkinliğini arttıracak yeni, ekonomik ve çevreci destek maddesi olarak mikroalgin kullanılabileceğini ortaya koymaktır. $Al_2O_3$/S. Platensis destekli Co katalizörü hazırlanırken kullanılacak olan mikroalg (Spirulina Platensis) türü literatürde belirtilen kültür ortamı hazırlanarak büyütülmüştür. Sodyum borhidrürün ($NaBH_4$) metanoliz reaksiyonundan hidrojen üretimi için katalizör destek maddesi olarak kullanılacak S. Platensis mikroalginin protonlanması için fosforik asit ($3M;H_3PO_4$) kullanılmıştır. Daha sonra mikroalg, $Al_2O_3$ ile 1;1 oranında karıştırılarak destek maddesi olarak hazır hale getirilmiştir. Bu modifiye edilmiş$Al_2O_3$/S. Platensis karışımı destek maddesi, kobalt iyonları ile yakıldıktan sonra indirgenmiş ve $Al_2O_3$/S. Platensis destekli Co katalizörü elde edilmiştir. $Al_2O_3$/S. Platensis destekli katalizöre $Co^{2+}$ metali ilavesi %10, %20, %30 ve %40 oranında eklenerek katalizör sentezi gerçekleştirilmiştir. Bu çalışmada, genel olarak deneyler 30 °C’de 0,025 g NaBH4 içeren 10 mL’lik metanol çözeltisinde 0,1 g katalizör varlığında bozundurularak zamana bağlı hidrojen miktarları ölçülmüştür. Deneysel çalışmalarda elde edilen hidrojen, gaz ölçüm sisteminde hacimsel olarak belirlenmiştir. Yapılan deneylerde farklı NaBH4 konsantrasyonları, katalizör miktarı ve farklı sıcaklık etkileri incelenmiştir. Deneylerde $NaBH_4$ miktarı incelenirken %1, %2.5, %5, ve %7.5 oranında $NaBH_4$ kullanılmış, katalizör miktarı etkinliği incelenirken ise sırasıyla 0.05, 0.1, 0.15, ve 0.25 g katalizör denenmiştir. $Al_2O_3$/S. Platensis destekli Co katalizörü varlığında NaBH4 metanolizi ile hidrojen üretiminde, sıcaklık etkisini araştırmak için 30, 40, 50 ve 60 °C olmak üzere dört farklı sıcaklık deneyi yapılmıştır. Al2O3/S. Platensis destekli Co katalizörü kullanılarak gerçekleştirilen deneylerde en iyi metal oranının %10 Co2+ olduğu belirlenmiştir. Bunun yanı sıra NaBH4’ün metanoliz reaksiyonundan elde edilen maksimum hidrojen üretim hızı 5747,1 mL $dak^{-1}gkat^{-1}$ ve katalizörün aktivasyon enerjisi 34.67 kJ $mol^{-1}$ olarak belirlenmiştir. Aynı zamanda, üretilen katalizörünün yapılan farklı $NaBH_4$ konsantrasyonları, katalizör miktarları ve sıcaklık deneyleri için $NaBH_4$ dönüşüm %’sinde azalma olmadığı belirlenmiştir.

Investigation of Hydrogen Production from Sodium Borohydride Methanolysis in the Presence of $Al_2O_3$ /Spirulina Platensis Supported Co Catalyst

In this study, $Al_2O_3$/Spirulina Platensis mixture was used for the first as support material. The aim is to demonstrate that microalgaecan be used as a new, economic and environmental support agent to increase the efficiency of the catalysts that will be eventually usedin the production of hydrogen. The strain was grown by preparing the culture medium containing all the necessary nutrients asdescribed in the literature. To synthesize the catalyst for the production of hydrogen through methanolysis of sodium borohydride($NaBH_4$), phosphoric acid ($3M;H_3PO_4$) was used as the protonation agent for the selected strain. After achieving sufficient density, thestrain was dried and mixed with $Al_2O_3$ in the ratio of 1/1. Modified $Al_2O_3$/S. Platensis mixture was finally blended with cobalt ionsand the mixture was burned. As a result of this procedure $Al_2O_3$/S. Platensis supported Co catalyst was produced. The catalyst wasprepared with the addition of different $Co^{2+}$ metal concentrations, 10%, 20%, 30%, and 40% respectively. In the present study, theexperiments were generally carried out with 10 ml methanol solution containing in 0.025 g $NaBH_4$ with 0.1 g catalyst at 30 °C. Thehydrogen obtained in experimental studies was determined volumetric in the gas measurement system. Here, different NaBH4concentrations, catalyst amount and different temperature effects were investigated. The effect of the amount of NaBH4 wasinvestigated with 1%, 2.5%, 5%, and 7.5% ratio of NaBH4 while the influence of the concentration of catalyst was carried out 0.05,0.1, 0.15, and 0.25 g catalysts. To investigate the performance of the catalyst on hydrogen production with NaBH4 methanolysis underdifferent temperatures, 30, 40, 50 ve 60 °C, relatively. The experiments by using $Al_2O_3$/S. Platensis supported Co Catalyst reveal thatthe best metal ratio was 10% Co2+. In addition, the maximum hydrogen production rate through methanolysis reaction of $NaBH_4$ bythis catalyst was found to be 5747.1 mL $min^{-1}gcat^{-1}$. Also, the activation energy was determined to be 34.67 kJ $mol^{-1}$. Moreover,different $NaBH_4$ concentrations, catalyst amounts and temperature studies of the fabricated catalyst were carried and it was discoveredthat there was no decline in the % of conversion for the synthesized catalyst.

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