类水滑石衍生锌基复合氧化物的硫化再生行为

Desulfurization and regeneration behaviors of zinc-based composite oxides derived from hydrotalcite

通过共沉淀法合成了具有片状堆积结构的类水滑石衍生锌基(钴或镍掺杂)复合金属氧化物,并将其用于中高温煤气脱硫。本文采用X射线衍射(XRD)、扫描电子显微镜(SEM)分析了脱硫剂及其前体的物相组成与形貌织构,发现镍(或钴)掺杂后脱硫剂的主要晶相仍为具有六方纤锌矿结构的氧化锌,且镍(或钴)的引入并未明显改变锌铝复合氧化物及其类水滑石前体的形貌结构。在固定床评价装置上研究了脱硫剂的硫化与再生行为,研究表明,锌镍(或钴)摩尔比为20时对应的掺杂型脱硫剂穿透时间(324min)最长,硫容(25.4%)最高。与未掺杂脱硫剂相比,掺杂镍(或钴)的脱硫剂最佳再生温度降低60℃左右。引入镍(或钴)后,脱硫剂不仅在多次硫化再生循环过程中维持高硫容,而且仍具有片状结构,硫化再生循环稳定性显著增强。

A stacked sheet-like zinc-based(cobalt or nickel doped)hydrotalcite-like composite metal oxide was synthesized by the co-precipitation method and then used for medium to high temperature gas desulfurization.X-ray diffraction(XRD)and scanning electron microscopy(SEM)were used to analyze the phase composition and morphology of the desulfurizers and their precursors.It was found that the main crystal phase of the desulfurizer with nickel(or cobalt)doping was still zinc oxide with hexagonal wurtzite structure,and the introduction of nickel(or cobalt)did not significantly change the morphology structures of both the zinc-aluminum composite oxide and its precursor.The vulcanization and regeneration behavior of the desulfurizers were studied on a fixed-bed reactor.The results showed that when the molar ratio of zinc to nickel(or cobalt)was 20,the longest breakthrough time(324min)and the highest sulfur capacity(25.4%)was achieved.Compared with the undoped desulfurizer,the optimal regeneration temperature of those doped with nickel(or cobalt)was reduced by about 60℃.After the introduction of nickel(or cobalt),the desulfurizer maintained not only a high sulfur adsorption capacity even after multiple desulfurization-regeneration cycles,but also the sheet-like structure,indicating an enhanced desulfurization-regeneration stability.