Chemical Engineering / Kimya Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/14
Browse
2 results
Search Results
Article Effective Synthesis of Cetyl Palmitate Over Co-Precipitated Wo3-Zro2 Catalysts(Springer Verlag, 2018) Mutlu, Vahide N.; Yılmaz, SelahattinThis study is focused on the development of solid acid catalysts for the synthesis of long chain fatty acids. A series of WO3-ZrO2 catalysts were prepared by co-precipitation method and tested in the synthesis of cetyl palmitate. The effect of WO3 loading (10, 15, and 20 wt% WO3) and calcination temperature (700 and 800 degrees C) on the catalyst properties and activity was investigated. XRD and Raman analysis confirmed that WO3 loading stabilized the tetragonal zirconia phase. Higher calcination temperature enhanced the acidities of the catalysts. WO3-ZrO2 catalysts were found to be very efficient for the synthesis of cetyl palmitate with high selectivity. These catalysts were tested for different reaction temperatures (135 and 162 degrees C), feed composition and catalyst amounts. The highest cetyl palmitate yield (98.4%) was obtained over the catalyst calcined at 800 degrees C with 15 wt% WO3, which had the highest total acidity. The catalysts preserved their activities up to three reuse.Article Citation - WoS: 11Citation - Scopus: 11Effect of Different Acidity Modifications on the Activity and Selectivity on H-Zsm5 Zeolites in N-Butene Isomerization(Springer Verlag, 2014) Kılıç, Emre; Yılmaz, SelahattinH-ZSM-5 was modified by silylation [tetraethylorthosilicate (TEOS) and triaminopropyltriethoxysilane], alkali (NaOH), acid (HCl) and ammoniumhexafluorosilicate (AHFS) treatments. The parent and modified zeolite forms were tested in n-butene isomerization. Modifications affected total acidities, the strength of the acid sites, pore sizes and surface areas of the H-ZSM-5 differently. The modifications decreased the conversion obtained by the parent catalyst. TEOS and alkali modifications did not promote formation of isobutene. Pre-alkali treatment before acid treatment increased selectivity to isobutene from 56.0 to 66.7 %, while conversion changed a little, it dropped from 52 to 50 %. AHFS modification provided the highest enhancement in selectivity to isobutene (87.5 %) for which n-butene conversion was dropped by about 10 % compared to H-ZSM-5. This was attributed to a slight modification of the pore size and to the reduction in strong and weak acid sites and generation of new Lewis acid sites.