钒对USY型分子筛的影响及氧化镧在钒捕集中的作用

Effect of vanadium on USY zeolite and lanthanum oxide on vanadium trapping

模拟催化裂化高温水热再生环境,采用X射线衍射、N2物理吸附、高分辨电子透射显微镜与NH3-程序升温热脱附等方法,研究了重金属元素钒(V)对催化剂活性组分水热超稳Y型分子筛(USY型分子筛)的破坏行为;在此基础上,研究了稀土氧化物氧化镧(La_(2)O_(3))对重金属V的捕集作用。结果表明:当分子筛负载较高质量分数的V时,分子筛的晶体结构遭到严重破坏;与未负载V的催化剂相比,负载质量分数为0.5%的催化剂,转化率降低了16.3个百分点,目标产物(液化气和汽油)收率显著降低,副产物干气、焦炭收率大幅增加;向模型催化剂中添加La_(2)O_(3)可以提高催化剂的重金属V捕集能力,在V负载质量分数为0.6%的情况下,含有La_(2)O_(3)的模型催化剂的原料油转化率和目标产物收率大幅增加。

The destruction behavior of heavy metal vanadium(V)on the active component of the catalyst—hydrothermal superstable Y zeolite(USY zeolite)was studied by X-ray diffraction,N2 physical adsorption,high resolution electron transmission microscope and NH3-programmed heating desorption,in the simulated high-temperature hydrothermal regeneration environment of fluid catalytic cracking.On this basis,the trapping effect of lanthanum oxide(La_(2)O_(3))on heavy metal V was studied.The results showed that the crystal structure of zeolite was seriously damaged when the zeolite was loaded with higher content of V.The conversion rate of the catalyst with mass fraction of 0.5%V loading decreased by 16.3 percentage points;the yield of target product(LPG and gasoline)decreased significantly;the yield of by-products dry gas and coke increased significantly,compared with the catalyst without V loading.The addition of La_(2)O_(3)to the model catalyst could significantly improve the heavy metal V capture capacity of the catalyst.The conversion rate of feed oil and the yield of target products of the model catalyst containing La_(2)O_(3)increased significantly,when the mass fraction of V was 0.6%.