Metal katkılı silika katalizörler kullanılarak selülozun levülinik asite dönüştürülmesi
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Tarih
2024
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Yayıncı
Bursa Teknik Üniversitesi, Lisansüstü Eğitim Enstitüsü
Erişim Hakkı
info:eu-repo/semantics/openAccess
Özet
Bugün birçok nedenle (kömür, petrol ve doğal gaz gibi birçok alanda kullanılan fosil yakıtların rezerv kapasitesindeki azalma, bu yakıtların kullanımından kaynaklanan çevresel kirlilik, atmosferdeki CO2 gibi sera gazlarının zararlı etkileri ve birçok diğer neden), fosil yakıtlara alternatif olarak kullanılabilecek farklı türde yakıtları keşfetmek, test etmek, geliştirmek ve kullanıma geçmiş ürünleri kullanmak için Ar-Ge çalışmaları yapmak üzere teknoloji stratejileri geliştirilmiştir. Bunun yanı sıra, hibrit sistemlerin geliştirilmesi ve deneme aşamasından sonra kullanımı da son yıllarda oldukça artmıştır. Ayrıca, birçok alanda kullanım bulan kimyasal ürünler de geliştirilmiş ve yeni teknolojilerin yaratılmasına öncülük etmiştir. Bu yöndeki teknolojik gelişmeler sayıca çoktur ve giderek popüler hale gelmeleriyle bu yönde yapılan yatırımların arttığı da gözlemlenmektedir. Biyokütle kaynaklı olarak üretilen çok yönlü bir esneklik platform kimyasalı olan levulinik asit, yakıtlar ve kimyasallara yönlendirilebilen çeşitli dönüşüm şekillerine sahip önemli bir kimyasaldır. Levulinik asit, biyokütlelerden sentezlenebilen esnek bir platform kimyasalı olarak kabul edilir ve petrol bazlı hammaddelere sürdürülebilir ve yenilenebilir bir alternatif sunar. Farmasötikler, polimerler, çözücüler ve gıda katkı maddeleri de dahil olmak üzere çeşitli endüstrilerde geniş bir uygulama yelpazesine sahip olması nedeniyle büyük bir potansiyele sahiptir. Levulinik asit; selüloz, hemiselüloz ve lignoselülozik malzemeler gibi biyokütlenin dönüştürülmesiyle üretilebilir. Dönüşüm süreci genellikle biyokütlenin hidrolizi ile şekerlerin serbest bırakılmasını, ardından bu şekerlerin dehidrasyonunu ve asit katalizli olarak levulinik aside dönüştürülmesini içerir. Biyokütle kaynaklarından olan levulinik asitin verimliliğini ve ürün verimliliğini artırmak için birçok metod geliştirilmiştir. Bu metodlar arasında asit hidrolizi, enzimatik hidroliz ve piroliz ve hidrotermal işlem gibi termokimyasal işlemler bulunmaktadır. Bu tez çalışmasında, SiO2 ve metal katkılı (Al, W, Sr, Ni ve Cu) katalizörler kullanılarak tek bir seferde selülozdan levulinik asit üretimi gerçekleştirilmiştir. Çözücü olarak su kullanılan deneylerde otoklavda 200°C'de 6 saat boyunca selülozun değerli kimyasallara dönüşümü test edilmiştir. Tüm sentezlenen katalizörlerin kristal yapıları, yüzey özellikleri, yüzey asitliği ve metal miktarları XRD, N2 adsorpsiyon/desorpsiyon analizi, piridin-FTIR analizi ve ICP analizi yapılarak karakterizasyon işlemleri gerçekleştirildi. Çalışmaların sonucunda, alüminyum birikiminin selülozun dönüşümünde önemli bir rol oynadığı belirlendi. SiO2'nin selüloz dönüşüm oranı %37,76 iken, alüminyum miktarına bağlı olarak selüloz dönüşüm oranı %100'e yükseldiği gözlemlendi. Diğer yandan, selülozun dönüşüm işleminde, 5-HMF'nin yanı sıra, levulinik asit, formik asit, astik asit ve furfural gibi değerli kimyasallara dönüştüğü tespit edildi. Selülozun tek adımda yüksek verimlilik ile levulinik asit, formik asit ve asetik asite dönüşümü Si-4Al-W katalizörü ile sağlanmıştır.
Today, for many reasons (the decrease in the reserve capacity of fossil fuels used in many areas such as coal, oil, and natural gas, environmental pollution caused by the use of these fuels, the harmful effects of greenhouse gases such as CO2 in the atmosphere and many other reasons), technology strategies have been developed to discover, test and create different types of fuels that can be used as alternatives to fossil fuels and to conduct R&D studies to use products that have been used. In addition, the development of hybrid systems and their use after the trial phase has increased considerably in recent years. In addition, chemical products that are used in many areas have also been developed and have led to the creation of new technologies. The number of technological developments in this direction is numerous and it is observed that the investments made in this direction are increasing as they become increasingly popular. Levulinic acid, a versatile flexible platform chemical produced from biomass, is an important chemical with various transformation forms that can be directed to fuels and chemicals. Levulinic acid is a flexible platform chemical that can be synthesized from biomass and offers a sustainable and renewable alternative to petroleum-based raw materials. It has great potential due to its wide range of applications in various industries including pharmaceuticals, polymers, solvents, and food additives. Levulinic acid can be produced by the conversion of biomass such as cellulose, hemicellulose and lignocellulosic materials. The conversion process usually involves the release of sugars by hydrolysis of biomass, followed by dehydration of these sugars and their acid-catalyzed conversion to levulinic acid. Many methods have been developed to increase the efficiency and product yield of levulinic acid from biomass sources. These methods include acid hydrolysis, enzymatic hydrolysis, and thermochemical processes such as pyrolysis and hydrothermal treatment. In this study, levulinic acid was produced from cellulose in a single step using SiO2 and metal-doped (Al, W, Sr, Ni, and Cu) catalysts. In experiments using water as a solvent, the conversion of cellulose to valuable chemicals was tested in an autoclave at 200°C for 6 hours. The crystal structures, surface properties, surface acidity, and metal amounts of all synthesized catalysts were characterized by XRD, N2 adsorption/desorption analysis, pyridine-FTIR analysis, and ICP analysis. As a result of the studies, it was determined that aluminum accumulation played an important role in the conversion of cellulose. While the cellulose conversion rate of SiO2 was 37.76%, it was observed that the cellulose conversion rate increased to 100% depending on the aluminum amount. On the other hand, it was determined that cellulose was converted into valuable chemicals such as levulinic acid, formic acid, acetic acid, and furfural in addition to 5-HMF during the conversion process. The conversion of cellulose to levulinic acid, formic acid, and acetic acid with high efficiency in a single step was provided by the Si-4Al-W catalyst.
Today, for many reasons (the decrease in the reserve capacity of fossil fuels used in many areas such as coal, oil, and natural gas, environmental pollution caused by the use of these fuels, the harmful effects of greenhouse gases such as CO2 in the atmosphere and many other reasons), technology strategies have been developed to discover, test and create different types of fuels that can be used as alternatives to fossil fuels and to conduct R&D studies to use products that have been used. In addition, the development of hybrid systems and their use after the trial phase has increased considerably in recent years. In addition, chemical products that are used in many areas have also been developed and have led to the creation of new technologies. The number of technological developments in this direction is numerous and it is observed that the investments made in this direction are increasing as they become increasingly popular. Levulinic acid, a versatile flexible platform chemical produced from biomass, is an important chemical with various transformation forms that can be directed to fuels and chemicals. Levulinic acid is a flexible platform chemical that can be synthesized from biomass and offers a sustainable and renewable alternative to petroleum-based raw materials. It has great potential due to its wide range of applications in various industries including pharmaceuticals, polymers, solvents, and food additives. Levulinic acid can be produced by the conversion of biomass such as cellulose, hemicellulose and lignocellulosic materials. The conversion process usually involves the release of sugars by hydrolysis of biomass, followed by dehydration of these sugars and their acid-catalyzed conversion to levulinic acid. Many methods have been developed to increase the efficiency and product yield of levulinic acid from biomass sources. These methods include acid hydrolysis, enzymatic hydrolysis, and thermochemical processes such as pyrolysis and hydrothermal treatment. In this study, levulinic acid was produced from cellulose in a single step using SiO2 and metal-doped (Al, W, Sr, Ni, and Cu) catalysts. In experiments using water as a solvent, the conversion of cellulose to valuable chemicals was tested in an autoclave at 200°C for 6 hours. The crystal structures, surface properties, surface acidity, and metal amounts of all synthesized catalysts were characterized by XRD, N2 adsorption/desorption analysis, pyridine-FTIR analysis, and ICP analysis. As a result of the studies, it was determined that aluminum accumulation played an important role in the conversion of cellulose. While the cellulose conversion rate of SiO2 was 37.76%, it was observed that the cellulose conversion rate increased to 100% depending on the aluminum amount. On the other hand, it was determined that cellulose was converted into valuable chemicals such as levulinic acid, formic acid, acetic acid, and furfural in addition to 5-HMF during the conversion process. The conversion of cellulose to levulinic acid, formic acid, and acetic acid with high efficiency in a single step was provided by the Si-4Al-W catalyst.
Açıklama
Anahtar Kelimeler
Kimya Mühendisliği, Chemical Engineering
