载体晶粒尺寸对CuY催化剂性能的影响

The Effect of the Support Grain Size on the Catalytic Performance of the CuY Catalyst

以偏铝酸钠和硅溶胶为主要原料,采用无导向剂法制备了不同粒径的分子筛NaY,利用离子交换反应,采用NH4NO3溶液将NaY转化为NH4Y分子筛.以NH4Y为载体,通过蒸气浸渍法制备了CuY催化剂.采用XRD、TEM、BET和XPS等技术对催化剂进行了表征分析.将CuY催化剂应用于甲醇氧化羰基化合成碳酸二甲酯(DMC)的反应,考察了载体粒径对催化活性的影响.结果表明:载体晶粒影响了孔结构,尤其是间隙孔的形成,进而影响催化剂的催化活性.当粒径约500 nm时,晶粒间隙孔恰好有利于DMC的形成,此时CuY催化剂表现出最优的催化活性,DMC基于甲醇的时空收率、甲醇转换率、DMC选择性分别为273.1 mg/(g·h)、6.5%、72.1%.

The NaY zeolite with different sizes was synthesized using sodium aluminate and silica sol as the main raw materials without seed gel.The NH4Y zeolite was prepared with ion-exchange of NH4NO3 from the as-prepared NaY zeolite and used as support to prepare the CuY catalyst through vapor impregnation.The CuY catalyst was characterized with XRD,TEM,BET and XPS and used to catalyze the oxidation carbonylation of methanol to dimethy carbonate.The effect of the support size on the catalytic activity was investigated.The results showed that the grain size of support affected the pore structure,especially the formation of mesopore,and the catalytic activity in turn.When the grain size was 500 nm,the intergranular pore is conducive to forming dimethy carbonate and the CuY catalyst exhibited an excellent catalytic activity with the space time yield based on methanol being 273.1 mg/(g·h),percentage of methanol conversion being 6.5%and selectivity of DMC being 72.1%.