Abstract
The synthesis of methacrylic acid from biomass-derived itaconic acid is a green route,for it can get rid of the dependence on fossil resource.In order to solve the problems on this route such as use of a precious-metal catalyst and a corrosive homogeneous alkali,we prepared a series of hydroxyapatite catalysts by an ionic liquid-assisted hydrothermal method and evaluated their catalytic performance.The results showed that the ionic liquid[Bmim]BF4 can affect the crystal growth of hydroxyapatite,provide fluoride ion for fluorination of hydroxyapatite,and adjust the surface acidity and basicity,morphology,textural properties,crystallinity,and composition of hydroxyapatite.The[Bmim]BF4 dosage and hydrothermal temperature can affect the fluoride ion concentration in the hydrothermal system,thus changing the degree of fluoridation of hydroxyapatite.High fluoride-ion concentration can lead to the formation of CaF2 and thus significantly decrease the catalytic performance of hydroxyapatite.The hydrothermal time mainly affects the growth of hydroxyapatite crystals on the c axis,leading to different catalytic perfor-mance.The suitable conditions for the preparation of this fluoridized hydroxyapatite are as follows:a mass ratio of[Bmim]BF4 to calcium salt=0.2∶1,a hydrothermal time of 12 h,and a hydrothermal temperature of 130 ℃.A maximal methacrylic acid yield of 54.7％was obtained using the fluoridized hydroxyapatite under relatively mild reaction conditions(250 ℃ and 2 MPa of N2)in the absence of a precious-metal catalyst and a corrosive homogeneous alkali.
基金项目
国家自然科学基金(21978066)
Basic Research Program of Hebei Province for Natural Science Foundation and Key Basic Research Project(18964308D)
Key Program of Natural Science Foundation of Hebei Province(B2020202048)
维普
万方数据