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BUHAR FAZINDA ETİL TERSİYER BÜTİL ETER (ETBE) SENTEZİNDE KULLANILAN POLİHEMA BAZLI SİLİKOTUNGSTİK ASİT KATALİZÖRLER

POLYHEMA BASED SILICOTUNGSTIC ACID CATALYSTS FOR VAPOR PHASE ETHYL TERT-BUTYL ETHER (ETBE) SYNTHESIS

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Abstract (2. Language): 
The activity of PolyHema-Silico tungstic acid (PH-STA) catalysts were investigated for vapor phase ETBE production conducted between 353-373K with isobutene/ethanol (IB/EtOH) molar ratio of 0.17. IB conversions to ETBE were found to be close to the equilibrium value with these synthesized catalysts. Activity test of PHSTA (25/75 v/v HEMA EGDMA) at 373K revealed a conversion value of 0.17 which was higher than that obtained in the presence of pure STA in our previous study. Comparison of the activity with pure STA revealed an improvement in the activity of PH-STA even though the active material in catalyst had been 8% (w/w). Catalyst stability was tested by repeated experiments conducted in the presence of PH-STA catalysts treated with ethanol. TGA analysis revealed changes in the molecular structure of synthesized catalysts with a change in temperature. Glass transition temperature (Tg) of polyHEMA was determined as 136 °C by DSC analysis. FTIR and XPS analyses of polyHEMA and polyHEMA based STA catalysts revealed formation of polymeric structure in addition to STA. Acidic nature of the synthesized catalysts were determined by DRIFTS analysis.
Abstract (Original Language): 
PoliHEMA-Silikotungstik asit katalizörlerin (PH-STA) aktivitesi buhar fazında, 353-373K sıcaklık aralığında, isobüten/etanol (IB/EtOH) mol oranının 0,17 olduğu reaksiyon koşullarında gerçekleştirilen ETBE üretimi için incelenmiştir. Çalışmada sentezlenen katalizörler varlığında IB’nin ETBE’ye dönüşümü denge dönüşüm değerine yakın bulunmuştur. PH-STA’nın (25/75 v/v HEMA/EGDMA) 373K sıcaklık değerinde gerçekleştirilen aktivite deneyleri sonucunda dönüşüm 0,17 olarak elde edilmiştir. Belirtilen dönüşüm değerine katalizördeki aktif madde miktarı (STA) ağırlıkça %8 varlığında ulaşılmıştır. Söz konusu dönüşüm değeri önceki çalışmalarımızda saf STA katalizörü ile elde edilen dönüşüm değerinden daha yüksektir. Katalizör dayanımı etanol ile işlem görmüş PH-STA katalizörler ile gerçekleştirilen deneyler ile test edilmiştir. TGA analizi ile sentezlenen katalizörlerin moleküler yapısının sıcaklıkla değişimi incelenmiştir. PoliHEMA’nın camsı geçiş sıcaklığı (Tg) DSC analizi sonucunda 136 °C olarak belirlenmiştir. PoliHEMA ve PH-STA katalizörlerine ait FTIR ve XPS analizleri polimer yapısının oluşumunu ve yapıdaki STA’nın varlığını göstermektedir. Katalizörlerin asidik karakteri gerçekleştirilen DRIFTS analizi ile belirlenmiştir.
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