活性组分浸渍顺序对Ni-Sn-Cr/活性炭催化乙酸甲酯气相羰基化合成醋酐性能的影响

Effects of Active Component Impregnation Sequence on Activities of Ni-Sn-Cr/Activated Carbon Catalysts in Gas Phase Carbonylation of Methyl Acetate to Acetic Anhydride

以活性炭(AC)为载体,采用等体积浸渍法,按照活性组分浸渍顺序的不同制备了一系列Ni-Sn-Cr/AC催化剂;在连续流动固定床反应器上考察了Ni-Sn-Cr/AC催化剂催化乙酸甲酯气相羰基化合成醋酐的性能,并采用XRD和N2物理吸附法对催化剂的物相和织构性质进行了表征。实验结果表明,在催化剂制备过程中3种活性组分Ni,Sn,Cr的加入顺序对Ni-Sn-Cr/AC催化剂的活性有较大影响;先浸渍Ni组分然后同时浸渍Sn和Cr组分的Ni/Sn-Cr/AC催化剂的活性最高,在n(CO)∶n(H2)=8、n(乙酸甲酯)∶n(CH3I)=7、n(CO)∶n(乙酸甲酯)=4、反应温度205℃、反应压力5.5MPa、气态空速1200h-1的条件下,Ni/Sn-Cr/AC催化剂上乙酸甲酯的转化率为38.5%,醋酐的选择性为80.3%。不同浸渍顺序制备的Ni-Sn-Cr/AC催化剂的织构性质并不是催化剂活性的决定因素。

With different impregnation sequences of active components, a series of Ni-Sn-Cr catalysts supported on activated carbon （AC） were prepared through impregnation. Catalytic performances of the prepared catalysts in gas phase carbonylation of methyl acetate （MeOAc） to acetic anhydride（AcOAC） were evaluated in a continuous flow fixed-bed reactor. Phase states and textural properties of the catalysts were analyzed by means of XRD and N2 physical adsorption. Experimental results indicated that impregnation sequences of Ni, Sn and Cr played an important part for performances of Ni-Sn-Cr/AC catalysts in the carbonylation. Ni/Sn-Cr/AC catalyst（ first impregnation with Ni and then co-impregnation with Sn and Cr） was the highest in the catalytic activity under reaction conditions of n（CO） ： n（H2） 8, n（MeOAc） ： n（CH3I） 7, n（CO） ： n（MeOAc） 4,205 ℃, 5.5 MPa and GHSV 1 200 h-1. MeOAc conversion and AcOAc selectivity reached 38.5% and 80.3%, respectively. Textural properties of Ni-Sn-Cr/AC catalysts with different impregnation sequences of active components were not determinant factor for their activities.