CuHY分子筛中铜离子的分布与吸附脱硫性能

采用等体积浸渍法制备具有不同Cu担载量的CuHY 分子筛吸附剂. 用X射线衍射(XRD)、比表面积(BET)和氨程序升温脱附(NH3-TPD)技术对分子筛吸附剂进行了表征, 并测定了CuHY 分子筛吸附剂在含二苯并噻吩(DBT)模拟柴油中的吸附脱硫性能; 通过多晶XRD确定了Cu2+在Cu8HY 分子筛笼内的结构与分布. 实验结果表明, 分子筛的骨架结构没有发生改变, 部分Cu2+进入Y型分子筛笼内, 分子筛样品强酸中心有所减少, 中强酸中心有所增加; 进入Y型分子筛笼内的Cu2+, 一部分处于β 笼的SI' 位, 另一部分位于分子筛超笼中的SIII位上, 并与笼内的水分子配位. 处于超笼中的SⅢ位Cu2+对模拟柴油中的DBT分子具有吸附作用, 是吸附脱硫的中心. 而当模拟柴油中存在萘时, 与DBT分子会产生竞争吸附.

Distribution of the Cu Ions in the CuHY Zeolite and Its Performance of Desulfurization

The CuHY zeolites’ absorbents with different Cu loadings were prepared via isovolumic impregnation method, and characterized via X-ray diffraction(XRD), BET surface area measurement and NH3 tempe-rature-programmed desorption(NH3-TPD) techniques. The CuHY zeolites absorbents’ performance of desulfurization was investigated in the model diseles containing dibenzothiophene(DBT). The crystalline structure of Cu8HY zeolite and the Cu2+ cations distribution in the cages of the Y zeolite was determined via powder XRD with Rietveld method. The results show that the frameworks of the Y zeolites were retained after Cu2+ cations entered the cages of the Y zeolites, the amounts of strong acid sites increased slightly and the amounts of mid-strong acid sites decreased slightly in the CuHY zeolite. At the same time, one part of Cu2+ cations entering the cages of Y zeolite, and situated at the sites SI' in the β cages, while another part of Cu2+ cations situated at sites SⅢ in the supercages and coordinated with water molecules in the supercages. The Cu2+ cations situating at sites SⅢ in the supercages can adsorb DBT molecules in the model diseles and become the centers of desulfurization. However, naphthalene molecules will resulting the competitive adsorption with DBT molecules if there are naphthalene molecules in the model diseles.