摘要
采用分步浸渍法制备了P改性的Cu/Al2O3催化剂,利用N2吸附-脱附、X射线衍射、红外光谱、紫外-可见光谱、H2程序升温还原、NH3程序升温脱附和N2O解离吸附等方法对催化剂进行了表征,考察了P含量及浸渍次序对催化剂结构及其催化甘油氢解反应性能的影响.结果表明,先浸渍P再浸渍Cu时,所制Cu/Al2O3催化剂酸性较高,同时还促进了Cu的分散.随P含量的增加,催化剂的酸量及Cu分散度提高,并且Cu与P物种的相互作用增强;然而,P含量较高时会覆盖Cu,使暴露的Cu表面降低.先浸渍Cu后浸渍P时,尽管也提高了相应催化剂的酸性,但对Cu分散的影响不大,并且还会覆盖Cu使暴露的Cu表面明显降低.先浸渍P明显提高了Cu/Al2O3上甘油氢解反应性能.在220oC,3MPa,质量空速2h?1以及H2/甘油摩尔比20的条件下,当P含量由0增加至6%时,甘油转化率从17.1%升至95.0%,1,2-丙二醇选择性从83.7%升至97.2%.这可归因于催化剂酸性的提高及Cu与P间的相互作用.
Phosphorus （P） modified Cu/A1203 catalyst was prepared by the successive impregnation method. The physicochemical properties of the catalyst were studied by means of N2 adsorption-desorption, X-ray diffraction, infrared spectroscopy, UV-visible diffuse reflectance spectroscopy, H2 temperature-programmed reduction, NH3 temperature-programmed desorption, and dissociative N20 adsorption. The ef- fects of the P content and the impregnation sequence on the structure and the performance of the catalyst for the hydrogenolysis of glycerol to 1,2-propanediol （1,2-PDO） were discussed. The addition of P to Cu/A1203 enhanced the acidity and Cu dispersion, especially when P spe- cies was impregnated prior to Cu. Also, there was a strong interaction between P and Cu species. However, the strong interaction leads to the coverage of Cu atoms with the P species at high P content. The coverage may be more serious when the P species was added after Cu to the catalyst. In the hydrogenolysis of glycerol, the addition of P prior to Cu remarkably promoted the catalytic performance of Cu/AI203. Under the conditions of 220 ℃, 3.0 MPa, space velocity of 2.0 h-1, and the H2/glycerol molar ratio of 20, as the P content increased from 0 to 6%, the glycerol conversion and the 1,2-PDO selectivity increased from 17.1% to 95.0% and from 83.7% to 97.2%, respectively. The promotion effect of P on the performance of Cu/Al2O3 is attributed to the increase of catalyst acidity as well as the strong interaction between Cu and P species.
出处
《催化学报》
SCIE
CAS
CSCD
北大核心
2012年第8期1410-1416,共7页
关键词
甘油氢解
铜基催化剂
磷
甘油
1
2-丙二醇
酸性
分散度
glycerol
hydrogenolysis
copper-based catalyst
phosphorus
glycerol
1,2-propanediol
acidity
dispersion
