碱土金属元素Mg对Cu^+-13X分子筛吸附脱硫性能的影响

Effect of Alkaline Earth Metal Element Mg on Adsorption Desulfurization Performance of Cu^+-13X Molecular Sieve

以13X分子筛为载体,采用液相离子交换法制备了Cu+-13X吸附剂和负载碱土金属元素Mg的Mg2+/Cu+-13X吸附剂,并利用XRD,XRF,ESEM和激光拉曼光谱仪(HR-800)等手段对所制备的吸附剂进行了表征。以含有噻吩和2-乙基噻吩的正己烷溶液为模拟燃料油,分别从静态吸附、吸附动力学两方面研究了两种吸附剂的脱硫性能,采用Langmuir模型和竞争吸附的Langmuir模型对单、双组分硫化物的静态吸附平衡数据进行拟合;采用Crank单孔扩散模型对吸附动力学数据进行拟合。结果表明,当Mg2+/Cu+-13X吸附剂中Mg的质量分数为3.35%时,吸附性能最佳;实验数据与模型吻合均很好,计算得到了Mg2+/Cu+-13X吸附剂对噻吩和2-乙基噻吩单组分的最大吸附量分别为140.7mg?g?1和183.8 mg?g?1,较Cu+-13X吸附剂对噻吩和2-乙基噻吩单组分的最大吸附量(130.2 mg?g?1和173.6 mg?g?1)分别提高了8.1%和5.9%,Mg2+/Cu+-13X双金属吸附剂的脱硫效果明显好于Cu+-13X吸附剂;负载的Mg2+作为一种助剂,使分子筛形貌分布更加均匀规整,并且增加了吸附剂的Lewis酸含量,使其还原性增强,吸附性能提高。

Adsorbents involving modified 13X zeolite with Cu＋or Mg2＋/Cu＋cations were prepared by liquid phase ion-exchange method. The properties of these adsorbents were characterized by means of XRD, XRF, ESEM and Horiba Labram HR-800. The adsorption desulfurization performances of Cu＋-13X and Mg2＋/Cu＋-13X were investigated by static adsorption equilibrium and their adsorption kinetics were tested by using thiophene and 2-ethylthiophene in the n-hexane as model transportation fuels. The static adsorption equilibrium data of the single component and bi-component adsorption systems were fitted by Langmuir model and competitive adsorption Langmuir model; the kinetics test data were fitted by Crank diffusion model. The experimental results show that the best adsorption desulfurization performance can be obtained by Mg2＋/Cu＋-13X with 3.35%of the Mg mass fraction;the experimental data were fitted well by the above models, the maximum sulfur adsorbing capacities of Mg2＋/Cu＋-13X for thiophene and 2-ethylthiophene are 140.7mg·g-1 and 183.8 mg·g-1, respectively. Adding alkaline earth metal element Mg in Cu＋-13X leads to 8.1% and 5.9%increase of the original thiophone and 2-ethylthiophene adsorption quantity of Cu＋-13X（130.2 mg·g-1 and 173.6 mg·g-1）, separately. The adsorption desulfurization property of Mg2＋/Cu＋-13X is apparently much better than that of Cu＋-13X, the presence of Mg2＋as a co-catalyst makes the morphology of 13X zeolite well-distributed and increases the Lewis acidity content of the adsorbent which enhances the reduction ability of the adsorbent,and finally leads to the improvement of its adsorption capacity.