Liquid-phase selective hydrogenation of crotonaldehyde on Au/Mg2AlO-hydrotalcite catalysts

• Main Authors: Hsing-Yu Chen, 陳星佑
• Other Authors: Yin-Zu Chen
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/09357584113589329883

碩士 === 國立中央大學 === 化學工程與材料工程研究所 === 97 === Liquid-phase hydrogenation of crotonaldehyde(UAL) to crotyl alcohol(UOL) was investigated on gold catalysts supported on a solid base of Mg2AlO-hydrotalcite. The Au/Mg2AlO catalysts were prepared using a modified deposition precipitation method without adjusting the pH of the initial HAuCl4 solution. The 2% Au/Mg2AlO catalyst hydrogenation for C=O bonds were more advantage than C=C bonds. The order of hydrogenation activity for different function groups over 2% Au/Mg2AlO catalyst was C=O (SAL)＞C=C/C=O (UAL)＞C=C (SOL). The selectivity of UOL was about 60%, and the selectivity of SAL+SOL was about 40%. Calcination temperatures of the Mg2AlO support and Au/Mg2AlO catalyst determined the ratio of gold states (Au3+/Au0) on the catalyst. A correlation between the gold states and the activity and selectivity of UOL was found. Increasing the Au3+/Au0 ratio of the Au/Mg2AlO catalysts increased the activity and selectivity of UOL. The effects of various parameters that are involved in the hydrogenation were studied, including the influences of solvent, reaction pressure, concentration of UAL, reaction temperature, and the addition of promoter. Au/Mg2AlO catalyst was different with the conventional hydrogenation catalysts, the activity of non-polar solvents were better than polar solvents. Increasing reaction pressure or decreasing concentration of UOL could improve activity. The activity and selectivity suddenly dropped with the reaction temperature up to 160°C. The doping of Fe significantly enhanced the activity, and slightly increased the selectivity. Gold catalysts supported on FeOOH, TiO2 and CeO2 also exhibited a high selectivity (> 60%), but they were much less active than that of 2%Au/Mg2AlO. However, the gold states could not determine the activity of gold catalysts with different supports, the nature of support would affect the reaction activity. Gold catalysts supported on a solid base of MgOx%/Al2O3 showed well activity comparing favorable with Au/Mg2AlO catalyst. Using solid base supports could prepare high activity gold catalysts for the liquid-phase hydrogenation of crotonaldehyde.