摘要
通过共沉淀法在不同焙烧温度下制备了新型无铬Cu-Al-Ba催化剂.测试了其在高压釜中将棕榈油甲酯加氢制备高碳醇的反应性能.结果表明催化剂的焙烧温度对催化性能有较大影响.在从150℃升至750℃的过程中,高碳醇的收率显示了三个阶段的变化,相应地,催化剂前驱体的热重(TG-DTG)曲线也显示了三个阶段的失重.X射线衍射(XRD)、X射线荧光(XRF),透射电镜-能谱分析-选区电子衍射(TEM-EDS-SAED)、N2物理吸附和程序升温还原(TPR)表征表明,催化剂是由一种孔雀石-勃石-碳酸钡前驱体制得的.在300或550℃焙烧后,催化剂组成为晶态的CuO、BaCO3和非晶态的Al2O3.其中,非晶态的Al2O3为CuO的高分散提供了大的比表面,杆状的BaCO3组分有利于提供微孔结构.在更高的焙烧温度750℃,新物相BaAl2O4的形成破坏了催化剂中的非晶态结构,导致其比表面积和孔容的急剧下降,并引起CuO物种的聚结.550℃焙烧的催化剂显示了最高的高碳醇收率,达到92.3%,这归因于其大的比表面积、大孔容和较高的CuO分散性.
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.
出处
《物理化学学报》
SCIE
CAS
CSCD
北大核心
2010年第8期2235-2241,共7页
Acta Physico-Chimica Sinica
关键词
加氢
酯
高碳醇
Cu-Al-Ba催化剂
焙烧温度
Hydrogenation
Ester
Higher alcohol
Cu-Al-Ba catalyst
Calcination temperature
