TitleCu-ZnO-Al2O3复合催化剂上甘油选择氢解合成丙二醇
Other TitlesSelective hydrogenolysis of glycerol to propylene glycol on hydroxycarbonate-derived Cu-ZnO-Al2O3 catalysts
Authors王帅
刘海超
Affiliation北京大学化学与分子工程学院,北京分子科学国家实验室,分子动态与稳态结构国家重点实验室,北京100871
Keywords甘油
选择性氢解
丙二醇

氧化锌
氧化铝
碱式碳酸盐前体
构效关系
催化剂稳定性
Glycerol
Selective hydrogenolysis
Propylene glycol
Copper
Zinc oxide
Alumina
Hydroxycarbonate precursor
Structure-activity relationship
Stability
Issue Date2014
Publisher催化学报
Citation催化学报.2014,(5),631-643.
Abstract分别采用均匀共沉淀法、沉积-沉淀法和传统的共沉淀法制备了3种具有相似组成的Cu-ZnO-Al2O3催化剂(CZA-HP, CAZ-DP和CZA-CP);同时还采用均匀共沉淀法制备了Cu-ZnO催化剂(CZ-HP)以用于比较. X射线衍射表征结果表明,以上方法制备的Cu-Zn-Al碱式碳酸盐前体中Cu2+, Zn2+和Al3+的混合均匀程度的顺序为CZA-DP<CZA-HP<CZA-CP. Al3+分散程度的提高和Al2O3与ZnO的紧密接触使得Cu-ZnO-Al2O3催化剂中金属Cu和ZnO具有更小的粒径.但ZnO-Al2O3间紧密接触也阻隔了Cu-ZnO-Al2O3催化剂中金属Cu与ZnO之间的相互作用.因此Al2O3的添加使得CZA-HP样品上的Cu粒子表现出最强的氧化还原能力.在473 K和6.0 MPa H2的反应条件下,以上三种Cu-ZnO-Al2O3催化剂均高选择性地催化甘油氢解为丙二醇(30%甘油转化率下的选择性>90%). Cu-ZnO-Al2O3催化剂表面单位Cu原子的本征活性顺序为CZA-DP < CZA-CP < CZ-HP < CZA-HP,与它们的氧化还原能力相一致.此外, Al2O3的添加还显著地抑制了Cu粒子在反应过程中的聚集,提高了催化剂的稳定性.经6次循环使用后, CZ-HP中Cu粒子的粒径从13.2增至45.2 nm,活性相应下降了45%;而CZA-HP中Cu粒子的粒径从8.3增至19.0 nm,活性仅下降了10%.
Three Cu-ZnO-Al2O3 catalysts with similar compositions were prepared by homogeneous coprecip-itation (CZA-HP), deposition-precipitation (CZA-DP), and conventional coprecipitation (CZA-CP). A Cu-ZnO catalyst was also prepared by homogeneous coprecipitation (CZ-HP) for reference. X-ray diffraction results showed that the degree of mixing of Cu2+, Zn2+, and Al3+ions in the Cu-Zn-Al hy-droxycarbonate precursor followed the order of CZA-DP<CZA-HP<CZA-CP. A more homogeneous aluminum distribution and intimate contact between Al2O3 and ZnO led to smaller CuO and ZnO crystallites in the CuO-ZnO-Al2O3 composite oxides, and consequently smaller Cu and ZnO crystal-lites in the final Cu-ZnO-Al2O3 catalysts. However, the intimate ZnO-Al2O3 contact hindered the in-teraction between Cu and ZnO in the Cu-ZnO-Al2O3 catalysts. As a result of these effects of Al2O3, for the samples other than CZA-CP, the Cu particles on CZA-HP showed the highest redox activity, which was characterized by N2O chemisorption-H2 temperature-programmed reduction. These catalysts catalyzed glycerol hydrogenolysis to propylene glycol with high selectivities above 90%at 30%glycerol conversion (473 K and 6.0 MPa H2). Their activities normalized per exposed surface Cu atom to give turnover frequencies increased in the order CZA-DP<CZA-CP<CZ-HP<CZA-HP, which was the order of the redox ability of the Cu particles. The addition of alumina increased the stability of Cu-ZnO catalysts. After six cycles (6 h per run), the activity of CZ-HP decreased by 45%accompanied by an increase of Cu crystallite size from 13.2 to 45.2 nm, while that of CZA-HP de-creased only by 10%with an increase of the Cu crystallite size from 8.3 to 19.0 nm. These results demonstrated the promoting effects of Al2O3 on the activity and stability of Cu-ZnO catalysts derived from the hydroxycarbonates.
URIhttp://hdl.handle.net/20.500.11897/78497
ISSN0253-9837
DOI10.1016/S1872-2067(14)60094-2
IndexedSCI(E)
EI
CPCI-S(ISTP)
中文核心期刊要目总览(PKU)
中国科技核心期刊(ISTIC)
中国科学引文数据库(CSCD)
Appears in Collections:化学与分子工程学院

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