低温固相法制备纳米氧化锌及其在脱硫中的应用

以乙酸锌和草酸为原料,采用低温固相法制备了纳米氧化锌,考察了表面活性剂和焙烧温度对氧化锌晶粒的影响,采用XRD、TG-DTA、IR和TEM等技术进行表征。以不同晶粒的氧化锌为锌源,采用等体积浸渍法制备一系列NiO/ZnO吸附荆;以噻吩/正庚烷为模型化合物,在固定床微反装置考察氧化锌晶粒对吸附剂脱硫性能的影响。结果表明,表面活性剂以十二烷基硫酸钠效果最好,合适的焙烧温度为400℃;制备的氧化锌呈球形,为六方晶系纤锌矿结构,具有较好的分散性,平均粒径约15 nm。活性评价表明,NiO/ZnO吸附剂对噻吩类硫化物具有较高的活性。可以实现超深度脱硫;氧化锌晶粒越小,相应NiO/ZnO吸附剂的脱硫活性越高;脱硫前后吸附剂的XRD谱图对比表明,脱硫过程中S以ZnS的形式固定在吸附剂上。

Synthesis and desulfurization behaviors of nanosized ZnO sorbent prepared by low-temperature solid-state reaction

Nanosized zinc oxide was prepared by low-temperature solid-state reaction using zinc acetate and oxalic acid as the starting material. Effects of surfactants and calcination temperature on grain size of ZnO were investigated. The samples were characterized by X-ray diffraction （XRD）, thermal analysis （TG-DTA） , infrared spectrometry（IR） and transmission and electron microscopy（TEM）. NiO/ZnO sorbents were prepared by successive incipient wetness impregnation, using zinc oxide with different grain size as zinc precursors. Effects of grain size of ZnO on desulfurization behaviors of the sorbents in a fixed bed micro-reactor, using thiophene/n-heptane as the model compounds. The results showed that the optimal condition for preparation of ZnO was using SDS as the surfactant and at calcination temperature of 400 ~C ; the ZnO as-prepared was of spherical shape and hexagonal wurtzite structure, with good dispersibility and grain size of 15 nm. Activity test results indicated that NiO/ZnO sorbent exhibited high desulfurization activity for thiophene, with deep desulfurization attainable ; the smaller the grain size of ZnO, the higher the activity of NiO/ZnO ; the XRD patterns of the sorbents before and after HDS reaction indicated that the sulfur was fixed onto the sorbent as ZnS.