Mn掺杂对Al-ZnO吸附剂常温脱除H_2S性能的促进作用

Promotional Effect of Mn doping on Desulfurization Properties of Al-ZnO Sorbents for H_2S Removal at Ambient Temperature

采用共沉淀法制备了ZnO、Al-ZnO和一系列xMn-Al-ZnO(x为Mn的物质的量)吸附剂,在常温条件下测试了样品的脱除H_2S性能。通过N_2物理吸附、XRD、SEM、XPS对吸附剂进行了表征,考察了其形貌结构及表面物理化学性质。脱硫性能测试结果显示,随着Mn含量的增加,吸附剂脱硫性能呈现先增大后减小再增大再减小的趋势,两个极值点分别出现在0.02Mn-Al-ZnO和0.08Mn-Al-ZnO。结合表征结果发现,不同Mn掺杂量对AlZnO吸附剂的脱硫性能表现出不同的促进作用。0.02 mol Mn掺杂能提高Al-ZnO吸附剂的比表面积至171.4m^2/g,进而促进其H_2S脱除性能;随着Mn掺杂量增加,吸附剂比表面积下降,但更多Mn进入ZnO晶格导致Mn和Zn之间相互作用增强,进而促进脱硫性能;然而,随着Mn掺杂量进一步增加,吸附剂比表面积继续下降,并且生成ZnMn_2O_4晶相,导致脱硫性能下降。0.08Mn-Al-ZnO的脱硫性能最佳,在25℃,体积空速3 000 h^(-1),H_2S质量浓度1.39×10^(-3)g/L条件下,穿透硫容为7.21%。结果表明,不同Mn掺杂量会导致吸附剂的形貌结构、晶相和表面物化性质发生不同程度的变化,由不同影响因素主导的x Mn-Al-ZnO吸附剂表现出脱硫性能的差异。

The desulfurization sorbents including ZnO,AI-ZnO and a series of xMn-Al-ZnO （x represent the amount of Mn） were synthesized by co-precipitation method,and then their desulfurization properties for H2S removal at ambient temperature were investigated. The morphology and properties of samples were characterized by N2 adsorption,XRD ,SEM and XPS,respectively. The results showed that the desulfurization performances of the samples first increased then decreased ,subsequently ,displayed the same change trend with the increasing doping anaount of Mn. And 0. 02 Mn-Al-ZnO and 0. 08Mn-Al-ZnO exhibited two extreme points. Additionally, different doping amount of Mn on the desulfurization perfommnce of Al-ZnO sorbents could demonstrate different promotion mechanism. 0. 02Mn-Al-ZnO gave an excellent desulfurization property,which was attributed to its large surface area of 171.4 m2/g. Despite the surface area dropped along with the increasing amount doping of Mn, more Mn atoms were incorporated into ZnO crystal lattice, which enhanced the interaction between Zn and Mn,resulting in a promotion of desulfurization performance. However,the further increasing doping amount of Mn caused the decrease of surface area and formation of ZnMn2O4 ,which led to a decline inthe dcsulfurization performance. And 0. 08Mn-Al-ZnO exhibited the highest breakthrough sulfur capacity of 7.21%at 25 ℃,GHSV of 3000 h-1,and HzS mass concentration of 1.39 × 10^-3 g/L. It was found that difference doping amount of Mn could change morphology,crystal structure and physicochemical properties. And different factors affected the desulfurization performance of the xMn-Al-ZnO sorbents.