Structure of the SO 4 22 /TiO 2 solid acid catalyst and its catalytic activity in cellulose acetylation Chen Meng 1 • Gui-Ping Cao 1 • Xue-Kun Li 1 • Yi-Zhen Yan 1 • En-You Zhao 1 • Lin-Yi Hou 1 • Hua-Yi Shi 1 Received: 12 December 2016 / Accepted: 17 February 2017 Ó Akade ´miai Kiado ´, Budapest, Hungary 2017 Abstract SO 4 2- /TiO 2 solid acid catalyst, a kind of green catalyst, was introduced as an alternative of sulfuric acid in the synthesis of cellulose acetate (CA). It has been investigated that SO 4 2- /TiO 2 presented prominent catalytic activity during this process. The degree of polymerization of CA obtained using SO 4 2- /TiO 2 catalyst was 1.7 times higher than that using H 2 SO 4 , which could influence the mechanical properties of CA considerably. In addition, the SO 4 2- /TiO 2 solid acid catalyst exhibited perfect reusability in the acetic acid system for cellulose acetylation, with traces of SO 4 2- leached during the reaction confirmed by NH 3 -TPD. It was investigated by XRD that the polymorphic of catalyst transformed from amorphous TiO 2 to anatase TiO 2 with the increase of calcination temperature and prolongation of calcination time, improving the catalytic activity of SO 4 2- /TiO 2 solid acid cat- alyst. The higher crystallinity it had, the better catalytic activity the SO 4 2- /TiO 2 catalyst exhibited. However, due to the decomposition of SO 4 2- on the catalyst surface, confirmed by TG-MS analysis, the catalytic activity of SO 4 2- /TiO 2 catalyst decreased sharply when the calcination temperature was above 550 °C. The struc- ture of SO 4 2- /TiO 2 solid acid catalyst has been investigated by FT-IR, and it can be confirmed that the SO 4 2- group was bidentate coordinated with TiO 2 . Keywords Cellulose Á Cellulose acetate Á SO 4 2- /TiO 2 solid acid catalyst Á Catalytic activity Á Reusability & Gui-Ping Cao gpcao@ecust.edu.cn 1 UNILAB, State Key Lab of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China 123 Reac Kinet Mech Cat DOI 10.1007/s11144-017-1165-3