Catalytic activity of acidic mesoporous CaZr_4(PO_4)_6 modified by doping Aluminum

A new type of acidic catalyst Al-CaZr4(PO4)6 is obtained by doping Aluminum in mesoporous CaZr4(PO4)6 belonging to NZP family synthesized via sol-gel method.The phase,doping amount of Al,pore structure and surface acidity of the samples are characterized by X-ray diffraction(XRD),X-ray fluorescence(XRF),N2 adsorption and NH3 temperature programmed desorption(NH3-TPD),respectively.The catalytic activity and selectivity of the synthesized acidic catalysts are investigated by using α-pinene isomerization as the probe reaction.The results show that mesoporous characteristics of the Al-doped CaZr4(PO4)6 are remained.When compared with the non-doped samples,the surface acidity of Al-containing CaZr4(PO4)6 is obviously improved.When α-pinene isomerization is catalyzed by Al-CaZr4(PO4)6-0.15 and Al-CaZr4(PO4)6-0.20 at 150℃ for 4 hours with 0.15 and 0.20 of the mole ratio of Al to Zr,respectively,the conversion of α-pinene can reach 40%-47%.However,the conversion of α-pinene catalyzed by non-doped samples is only 3% under the same condition.Therefore,the catalytic activity of mesoporous CaZr4(PO4)6 can be greatly improved by doping Al.