Cu-Ni/γ-Al_2O_3双功能催化剂上二甲醚水蒸气重整制氢

Dimethyl Ether Steam Reforming for Hydrogen Production over Cu-Ni/γ-Al_2O_3 Bi-Functional Catalyst

用沉积-沉淀法分别制备了Cu/γ-Al2O3、Ni/γ-Al2O3和Cu-Ni/γ-Al2O3催化剂,并研究了它们在二甲醚水蒸气重整(DMESR)制氢反应中的催化性能.采用比表面积测定(BET)、X射线衍射(XRD)、H2程序升温还原(H2-TPR)、X射线光电子能谱(XPS)、NH3程序升温脱附(NH3-TPD)、程序升温氧化(TPO)和透射电子显微镜(TEM)等表征手段对催化剂的物相结构、微观形貌、还原性能、表面酸性和积炭特性等进行了研究.结果表明:Cu、Ni均为二甲醚水蒸气重整制氢的活性组分,Cu、Ni和γ-Al2O3之间存在着相互作用;镍的加入可以有效地提高铜组分在γ-Al2O3上的表面富集与分散,优化铜组分的分布状态,促进CuO颗粒的细小化,并可增强铜组分和载体之间的相互作用,有效地防止铜晶粒的团聚,从而提高催化剂的活性及稳定性;铜的加入可以改善催化剂中金属镍的分散性,减少镍颗粒的尺寸,降低催化剂对CH4的选择性,提高催化剂的H2产率,并在一定程度上抑制了积炭的形成与沉积.在350℃的温度下,反应进行100h后,Cu-Ni/γ-Al2O3催化剂仍保持95%的二甲醚转化率,说明该催化剂具有较好的活性和稳定性.

Cu/γ-Al2O3,Ni/γ-Al2O3,and Cu-Ni/γ-Al2O3 catalysts were prepared using the deposition-precipitation method and the catalytic performances for hydrogen production during dimethyl ether steam reforming（DME SR） were investigated.The structure and surface characteristics of these catalysts were analyzed by Brunauer-Emmett-Teller（BET）,X-ray diffraction（XRD）,H2 temperature-programmed reduction（H2-TPR）,X-ray photoelectron spectroscopy（XPS）,NH3 temperature-programmed desorption（NH3-TPD）,temperature-programmed oxidation（TPO）,and transmission electron microscopy（TEM）.It was revealed that both copper and nickel were active components during DME SR and there were interactions among Cu,Ni,and γ-Al2O3.Nickel addition improved copper dispersion to obtain small copper crystallites,and strengthened the interaction between copper and γ-Al2O3 so as to prevent copper agglomeration.Copper addition also improved nickel dispersion and the smaller nickel particle size suppressed CH4 formation,which prevented coke formation.Therefore,Cu-Ni/γ-Al2O3 with superior catalytic activity and stability was obtained.During100 h durability testing,the Cu-Ni/γ-Al2O3 maintained about 95% DME conversion and did not show obvious deactivation.