完全液相法制备中原料配比对二甲醚合成催化剂结构和性能的影响

Effect of Composition of Raw Materials on Structure and Dimethyl Ether Synthesis Activity of Cu-Zn-Al Catalyst Prepared by Complete Liquid Phase Method

利用完全液相法制备了Cu-Zn-Al双功能催化剂,考察了原料配比对催化剂结构和催化CO加氢合成二甲醚反应性能的影响,用XRD,N2吸附,XPS和H2-TPR等方法对催化剂进行了表征.结果表明,在Cu-Zn-Al基二甲醚合成催化剂中,Zn和Al在催化剂表面的竞争富集是主要过程,增加投料中Cu的比例并不能显著增加Cu在催化剂表面的含量,因为在反应环境中,Al也会富集,并且在Cu含量高时富集得更快.当投料组成为n(Cu)∶n(Zn)∶n(Al)=2∶1∶4时,催化剂的体相结构和表面性质最好(Cu晶粒度最小,Cu分散度最高,还原性能最佳,组分间相互作用最强,最可几孔径最大),催化剂的综合性能最好.

The Cu-Zn-Al bifunctional slurry catalyst was prepared by a complete liquid phase method and characterized by X-ray diffraction,N2 adsorption, X-ray photoelectron spectroscopy, and H2 temperature-programmed reduction. The effects of Al content and Cu/Zn molar ratio on the catalytic activity of the catalyst for dimethyl ether synthesis from syngas were investigated. The competitive enrichment of Zn and AI on the catalyst surface was dominating, and increasing the Cu content could not obviously increase the Cu amount on the catalyst surface. This is because Al was enriched faster on the catalyst surface than Cu under the reaction conditions in the case of the catalyst with higher Cu content. The catalyst with n （Cu） ： n （Zn） ： n （Al） = 2：1：4 had the most favorable bulk structure and surface properties, such as the least Cu particle size, the highest dispersion degree, the excellent reductive character, the most strong interaction between dius. Therefore, this catalyst showed the best catalytic performance.