Chemical Engineering / Kimya Mühendisliği

Permanent URI for this collectionhttps://hdl.handle.net/11147/14

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Author: search.filters.author.Yüksel, AslıPublication Index: search.filters.publicationIndex.TR-Dizin

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  • Article
    Citation - WoS: 1
    Citation - Scopus: 1
    Selective Catalytic Hydrogenation of Cellulose Into Sorbitol With Ru-Based Catalysts
    (TÜBİTAK, 2022) Orak, Ceren; Sapmaz, Aycan; Yüksel, Aslı
    Sorbitol is one of the platform chemicals and can be produced from various renewable and sustainable sources via different processes. Hydrothermal liquefaction is an effective and promising approach to produce sorbitol, since the subcritical reaction media and appropriate catalysts provide a selective production of platform chemicals. In this study, sorbitol was produced from different renewable sources (cellulose and glucose) in the presence of Ru-based catalysts (Ru/SiO2, Ru/AC, Ru/SBA-15, and Ru/SBA-15-SO3) under subcritical conditions. The highest cellulose conversion was achieved as 90% in the presence of Ru/SBA-15-SO3 for 1 h of reaction duration. The highest sorbitol yield (%) by hydrothermal liquefaction of cellulose was obtained as 6.2% by using Ru/AC for 1 h of reaction duration. A total of 99.9% of glucose conversion was achieved in the presence of all catalysts. The highest sorbitol yield (%) by hydrothermal liquefaction of glucose was found as 3.8% for 1 h of reaction duration. Owing to the results of GC-MS analysis, the intermediate products were identified, and, thus, a reaction pathway was proposed.
  • Article
    Hydrothermal Treatment of Cellulose in Hot-Pressurized Water for Thr Production of Levulinic Acid
    (Uludağ Üniversitesi, 2016) Yüksel, Aslı
    Bu makalede selülozu değerli kimyasallara, özellikle levulinik asite, parçalamak amacı ile suyun kaynama noktası üzerinde ve kritik noktası altında (374. 15 °C ve 22.1 MPa) çalışılan sıcak-basınçlı su, reaksiyon ortamı olarak kullanılmıştır. Reaksiyon sıcaklığı, basıncı, süresi, oksitleme ajanı çeşidi ve miktarının selülozun parçalanmasına ve ürün dağılımına olan etkileri incelenmiştir. Selüloz bozunma yüzdesi ve levulinik asit oluşum verimini kıyaslamak amacı ile deneyler hem oksitleme ajanı (H2SO ve H2O) kullanarak, hem de kullanmayarak gerçekleştirilmiştir. Farklı sıcaklık (150 - 280 °C), basınç (5-64 bar) ve tepkime sürelerinde (30 - 120 dk.) oluşan likit ürünlerin analizleri HPLC ve GC-MS ile gerçekleştirilmiştir. Ana sıvı ürünler olarak levulinik asit, 5-HMF ve formik asit tespit edilmiştir. 125 mM sülfürik asit eklenerek 200 °C sıcaklıkta ve 60 dk boyunca gerçekleştirilen tepkime sonucunda, %73 selüloz bozunmuş ve %38 verimle levulinik asit elde edilmiştir.