Akademik Veri Yönetim Sistemi
Journal of the Faculty of Engineering and Architecture of Gazi University, cilt.27, sa.3, ss.641-650, 2012 (SCI-Expanded)
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.