NaOH浓度对Cu2O结构及甲醛乙炔化性能的影响

Effect of Na OH Concentration on Structure and Catalytic Performance of Cu_2O for Formaldehyde Ethynylation

以CuCl_2·2H_2O为铜源,NaOH为沉淀剂,L-抗坏血酸钠为还原剂,采用液相还原法制备了Cu_2O,并将其应用于甲醛乙炔化反应制1,4-丁炔二醇.借助傅里叶变换红外光谱(FT-IR)、拉曼光谱(Raman)、X射线粉末衍射(XRD)、X射线光电子能谱(XPS)、扫描电子显微镜(SEM)和H_2程序升温还原(H2-TPR)等手段研究了NaOH浓度对Cu_2O结构、性质及催化性能的影响.结果表明,调变NaOH浓度改变了Cu2O的结晶度与粒径,从而使Cu_2O表现出不同的炔化性能.低NaOH浓度时,Cu_2O结晶度低,粒径小,易被还原为非活性的金属Cu;高浓度时,Cu_2O结晶度过高,粒径大,难以转化为活性物种炔化亚铜,两者均造成催化剂活性较低.而中等浓度的NaOH使Cu_2O具有了适宜的结晶度与粒径大小,Cu_2O可高效转化为炔化亚铜活性物种,表现出最优的炔化性能.

Cuprous oxide （Cu2O） samples were prepared by liquid reduction method using copper chloride as cop- per source, sodium hydroxide as precipitant and L-ascrobate as reducer, and the as-prepared Cu2O was used for 1,4-butynediol synthesis by formaldehyde ethynylation reaction. The effect of NaOH concentration on structure and catalytic performance of Cu2O was investigated, combined with Fourier transform infrared spectroscopy （ FT-IR）, Raman spectroscopy, X-ray diffraction （XRD）, X-ray photoelectron spectra （XPS）, scanning electron microscope （SEM） and H2-temperature programmed reduction （H2-TPR）. The results showed that modulating NaOH concen- tration changed crystallinity and particle size, resulting in difference in ethynylation property. At lower concentra- tion of NaOH, Cu2O was easy to be converted to inactive metallic Cu; At higher NaOH concentration, Cu2O was difficult to be converted to active species cuprous acetylide, the above two samples showed poor catalytic activity. Medium concentration of NaOH made the Cu2O have appropriate crystallinity and particle size and show the superior catalytic performance for formaldehyde ethynylation.