Preparation of limonene by isomerization of α-pinene with SAPO-5 aluminum phosphate molecular sieve
SAPO-5 And FeSAPO-5 aluminum phosphate molecular sieves were successfully prepared by the classical hydrothermal synthesis method,characterized by XRD,FTIR,SEM,BET and NH3-TPD,and used to catalyze the isomerization of α-pinene to limonene.The results showed that the Fe-modified molec-ular sieve FeSAPO-5 crystal had an AFI topology with a size of about 4～5 μm and a cylindrical shape;the BET was about 310 m3/g and the total acid amount was 802 μmοl/g.Combined with the characteriza-tion results,it was found that the high catalytic activity of the FeSAPO-5 molecular sieve was attributed to the increasing the specific surface area and the amount of medium-strong acid.The conversion of α-pinene and the selectivity of limonene about SAPO-5 and FeSAPO-5 were 49.3%and 50%,75.7%and 54.4%respectively,and with an increase 16.2%yield of limonene.With three cycle and five repeatability experi-ments,which showed that FeSAPO-5 aluminum phosphate molecular sieve exhibited good selectivity and stability in the preparation of limonene from α-pinene.
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