University of Kashan Journal of Nanostructures 2251-7871 11 2 2021 04 01 Effect of the loading of di- and tri-valent metal cations on the performance of sulfated silica-titania nano-catalyst in the esterification reaction 221 235 111596 10.22052/JNS.2021.02.003 EN Khalid Al-Qaysi Department of Chemical Engineering, University of Technology, P.O. Box 19006, Baghdad, Iraq Hamed Nayebzadeh Esfarayen University of Technology, Esfarayen, North Khorasan, Iran Naser Saghatoleslami Department of Chemical Engineering, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran Jabbar Gardy School of Chemical and Process Engineering, Faculty of Engineering and Physical Sciences, University of Leeds, West Yorkshire, Leeds, LS2 9JT, United Kingdom Journal Article 2020 09 04 In this study, a series of sulfated silica-titania catalysts were modified by metal cations (Al, Co, Zr, Cr, and Zn) to enhance the catalytic activity and stability of sulfated silica-titania in the esterification reaction. The results indicated that the sulfate phases of sulfated silica-titania were mostly changed to TiO(SO4) by the incorporation of support cations. It affected the acidity content of the samples and the bonding strength between the sulfate group and the support surface. Moreover, the mean pore size was drastically increased which had a positive influence on the activity of the sample in the esterification reaction. The results of catalytic activity showed that all the samples had suitable activity at 120°C, whereas the sulfated silica-titania catalyst that was reinforced by Al3+ exhibited less activity reduction by setting the temperature to 90°C. The highest conversion of oleic acid (90.7 ± 2%) was obtained under optimal reaction conditions including the temperature of 90°C, methanol/oleic acid molar ratio of 9:1, 3 wt.% catalyst, and reaction time of 3 h. The sulfated silica-titania modified by Al3+ also exhibited good catalytic stability for six cycles while a high reduction in the activity of sulfated silica-titania catalyst was observed.  https://jns.kashanu.ac.ir/article_111596_7c052031b36d40bda1b306200cd5611d.pdf