Acta Phys. -Chim. Sin. ›› 2010, Vol. 26 ›› Issue (08): 2235-2241.

• CATALYSIS AND SURFACE STRUCTURE •

Influence of Calcination Temperature on the Performance of Cu-Al-Ba Catalyst for Hydrogenation of Esters to Alcohols

YUAN Peng, LIU Zhong-Yi, SUN Hai-Jie, LIU Shou-Chang

1. Department of Chemistry, Zhengzhou University, Zhengzhou 450001, P. R. China
• Received:2010-01-11 Revised:2010-03-13 Published:2010-07-23
• Contact: LIU Shou-Chang E-mail:liushouchang@zzu.edu.cn

Abstract:

Novel chromium-free Cu-Al-Ba catalysts were prepared by co-precipitation and were calcined at different temperatures. Their performance during the hydrogenation of palm oil esters to higher alcohols was evaluated in an autoclave. Results showed that the catalytic properties of the catalysts were greatly influenced by the calcination temperatures. The yield of higher alcohols showed three steps when the calcination temperature of the catalysts was raised from 150 to 750 ℃. The thermogravimetric (TG-DTG) curves of the precursor also exhibited three steps related to mass loss. X-ray power diffraction (XRD), X-ray fluorescence (XRF), transmission electron microscopy-energy dispersive spectrometry-selected area electron diffraction (TEM-EDS-SAED), N2-physisorption, and temperature- programmed reduction (TPR) characterization revealed that the catalysts were obtained from a malachite-boehmite-BaCO3 precursor. After calcination at 300 or 550 ℃, the catalysts were found to be composed of crystalline CuO and BaCO3 as well as amorphous Al2O3. Amorphous Al2O3 has a large surface area which results in a high dispersion of CuO. Rod-like BaCO3 helps in the provision of micropores. The formation of BaAl2O4 at a calcination temperature of 750 ℃ destroys the amorphous structure and causes a sharp decline in the surface area and pore volume of the catalyst and this causes CuO aggregation. An optimal higher alcohol yield of 92.3% was obtained over the Cu-Al-Ba catalyst that was calcined at 550 ℃ due to its larger surface area, larger pore volume, and higher degree of CuO dispersion.

MSC2000:

• O643