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 preciousmetal 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

]

BF

4

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

]

BF

4

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 CaF

2

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 performance. The suitable conditions for the preparation of this fluoridized hydroxyapatite are as follows: a mass ratio of [Bmim

]

BF

4

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 hydrox

yapatite under relatively mild reaction conditions (250℃ and 2 MPa of N

2

) in the absence of a precious-metal catalyst and a corrosive homogeneous alkali.