铁尾矿无溶剂法绿色高效制备ZSM-5分子筛

Sustainable synthesis of ZSM-5 zeolite from iron ore tailings

针对河北承德某地区铁尾矿硅铝含量高的特点,以该尾矿为原料制备ZSM-5分子筛。目前,以固体废弃物为原料合成分子筛通常采用水热法,合成工艺复杂、单釜利用率低且产生废水,严重限制了以固体废弃物为原料合成分子筛的大规模应用。该研究提出以无溶剂法合成ZSM-5分子筛,在分子筛合成过程中无液体溶剂参与,因此更加绿色环保。研究表明,ZSM-5分子筛最佳合成参数为:HDA/SiO_(2)=0.1、Na2CO3·10H2O/SiO_(2)=0.4,150℃晶化6 d,此时得到的ZSM-5分子筛同时具有介、微复合孔结构,其中微孔表面积为213.2 m^(2)/g,外表面积为95.53 m^(2)/g。此外,无溶剂法合成分子筛的元素利用率高于传统水热法,无溶剂法Si和Al的元素利用率分别为94.83%、95.89%,而水热法仅为80%左右。

In view of the high silicon and aluminum content of iron ore tailings(IOT)in Chengde,Hebei province,ZSM-5 zeolite was prepared with IOT as the raw materials.At present,the synthesis of zeolite from solid waste usually uses hydrothermal method,which is a complex synthesis process with low utilization rate of single reactor and produces wastewater.Our approach focused on reutilization of IOT by converting it to ZSM-5 via solvent-free method.It shows that the optimal synthesis parameters of ZSM-5 zeolite are HDA/SiO_(2)=0.1,Na_(2)CO_(3)·10H_(2)O/SiO_(2)=0.4,and crystallization at 150℃ for 6 days.The obtained ZSM-5 zeolite has bimodal meso-and micro-porous structure,with a surface area of micropores of 213.25 m^(2)∙g^(−1) and an external surface area of 95.53 m^(2)∙g^(−1).In addition,the elemental utilization rate of the solvent-free method is higher than that of the conventional hydrothermal method,and the elemental utilization rates of Si and Al for the solvent-free method are 94.83% and 95.89%,respectively,while those for the hydrothermal method were only 80%.