摘要
通过在Cu/AC催化剂中添加稀土助剂Ce,考察不同的浸渍顺序对CuCe/AC(活性炭)催化剂表面结构及其催化甲醇气相氧化羰基化合成碳酸二甲酯性能的影响,并采用XRD、XPS、H2-TPR、AAS和HR-TEM等表征了催化剂活性组分含量、分散状态和价态等性质。发现共浸渍法制备的催化剂,Ce对活性组分Cu在活性炭表面的分散起到一定的促进作用;先浸渍Cu后浸渍Ce制备的催化剂,后浸渍的Ce覆盖部分Cu组分,使这些Cu组分难以还原并无法与反应物分子接触,导致其催化性能有所降低;而先浸渍Ce后浸渍Cu制备的催化剂,Ce组分和Cu组分产生相互作用,使表面存在较多分散均匀的Cu(0)和Cu髣物种,其催化性能最佳,碳酸二甲酯的时空收率及选择性分别达到了142 mg·g-1·h-1和85%。
The effect of impregnation sequence on the surface structure and catalytic performance of CuCe/AC （Activated carbon）（by adding rare earth Ce promoter to Cu/AC）catalyst was studied for gas-phase oxidative carbonylation of methanol to dimethyl carbonate. The active component content, surface dispersion and valence state of as-prepared catalysts were characterized by X-ray diffraction （XRD）, X-ray photoelectron spectroscopy （XPS）, H2-temperature programmed reduction （H2-TPR）, High resolution transmission electron microscope （HR- TEM）. The results show that Ce promoter plays a key role for active component Cu to disperse on the surface of activated carbon in CuCe/AC catalyst prepared by co-impregnation. The Cu components are difficult to be reduced and difficult to contact with reactant molecules for CuCe/AC catalyst prepared by first impregnation with Cu and then with Ce because part of Cu components are covered by Ce impregnation leading to the decrease of catalytic activity. For CuCe/AC catalyst prepared by first impregnation with Ce and then with Cu, the Ce and Cu components interact with each other, resulting in an optimal catalytic performance because of a more uniform dispersion of Cu （0） and Cu（I） species on the surface of the catalyst. The space time yield and selectivity of dimethyl carbonate are 142 mg·g^-1·h^-1 and 85%, respectively.
出处
《无机化学学报》
SCIE
CAS
CSCD
北大核心
2013年第12期2575-2581,共7页
Chinese Journal of Inorganic Chemistry
基金
国家自然科学基金(No.20976113
21276169)
山西省科技攻关项目(20120321003-03)
山西省归国留学基金(No.20100038)资助项目
关键词
助剂Ce
浸渍顺序
CU
AC催化剂
氧化羰基化
Ce promoter
impregnation sequence
Cu/AC catalyst
oxidative carbonylation
