A high performance co-precipitation CdAl2O4 catalyst for the isomerization of dipotassium 1,8-naphthalenedicarboxylate

CdO and co-precipitation CdAl2O4 (PreCdAl2O4) catalysts were prepared and used in the isomerization reaction of dipotassium 1,8-naphthalenedicarboxylate. The catalyst samples were characterized by X-ray powder diffraction, scanning electron microscopy, inductively coupled plasma, nitrogen physical adsorption, Fourier transform infrared, X-ray photoelectron spectrum and NH3-temperature programmed desorption. The results reveal that the crystal structure of all samples is almost unchanged. However, compared with CdO, the PreCdAl2O4 catalysts exhibit a smaller particle size and stronger acid. This feature may be attributed to the fact that a small amount of Al atoms are introduced into the catalyst structure in the synthesis process of CdAl2O4 by co-precipitation method. Furthermore, the effects of different catalyst, calcination temperature of catalyst, Cd/Al molar ratio of PreCdAl2O4 catalysts and reaction temperature on the isomerization reaction were investigated. The experimental results show that the optative catalyst was PreCdAl2O4-0.95 of calcination at 673 K. Meanwhile, a dipotassium 2,6-naphthalenedicarboxylate selectivity of 90.6 % and dipotassium 1,8-naphthalenedicarboxylate conversion of 98.0 % was obtained when this reaction was carried out at 723 K for 2 h in 1.5 MPa CO2 atmosphere.