title: The adsorption and reaction of a titanate coupling reagent on the surfaces of different nanoparticles in supercritical CO2.
abstract: The adsorption and reaction in supercritical CO2 of the titanate coupling reagent NDZ-201 on the surfaces of seven metal oxide particles, SiO2, Al2O3, ZrO2, TiO2 (anatase), TiO2 (rutile), Fe2O3, and Fe3O4, was investigated. FTIR and TG analysis indicated that the adsorption and reaction were different on different particle surfaces. On SiO2 and Al2O3 particles, there was a chemical reaction of the titanate coupling reagent on the surfaces. On the surfaces of ZrO2 and TiO2 (anatase) particles, there were two kinds of adsorption, weak and strong adsorption. On the surfaces of TiO2 (rutile), Fe2O3, and Fe3O4 particles, there was only weak adsorption. The acidity or basicity of the OH groups on the particle surface was the key factor that determined if a surface reaction occurred. When the OH groups were acidic, the titanate coupling reagent reacted with these, but otherwise, there was no reaction. The surface density of OH groups on the original particles and the amount of titanate coupling reagent adsorbed and reacted were estimated from TG analysis. The reactivity of the surface OH groups of Al2O3 particles was higher than that of the SiO2 particles.
authors.affiliation: Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China.
authors.forename: Zhi-Wen
authors.initials: ZW
authors.lastname: Wang
authors.forename: Ting-Jie
authors.initials: TJ
authors.lastname: Wang
authors.forename: Zhan-Wen
authors.initials: ZW
authors.lastname: Wang
authors.forename: Yong
authors.initials: Y
authors.lastname: Jin
mesh_terms: D000327:Adsorption; D000537:Aluminum Oxide / Q000737:chemistry; D002245:Carbon Dioxide / Q000737:chemistry*; D005290:Ferric Compounds / Q000737:chemistry; D052203:Ferrosoferric Oxide / Q000737:chemistry; D053758:Nanoparticles / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry*; D011312:Pressure; D012680:Sensitivity and Specificity; D012822:Silicon Dioxide / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods; D013499:Surface Properties; D013696:Temperature; D013818:Thermogravimetry; D013997:Time Factors; D014025:Titanium / Q000737:chemistry*; D015040:Zirconium / Q000737:chemistry
chemical_list: D005290:Ferric Compounds; D010087:Oxides; D002245:Carbon Dioxide; C009495:titanium dioxide; C000499:ferric oxide; D012822:Silicon Dioxide; D015040:Zirconium; D014025:Titanium; D000537:Aluminum Oxide; C028541:zirconium oxide; D052203:Ferrosoferric Oxide