| Medium-high temperature coal gas desulfurization is regarded as a promising clean coal technology due to its high efficiency and low environmental pollution. Supported sorbent is considered as a highly efficiency desulfurizer for medium-high temperature coal gas because it has much bigger surface and lots of pores which makes H2S much more easily contacted to the active component.In this thesis, semi-coke supported mixed metal oxide (ferrite, zinc, manganese) sorbent was prepared with assistant of ultrasonic irradiation. The sorbents were characterized by BET, SEM-EDS, XPS and mechanical strength, moreover, the behavior of semi-coke supported mixed metal oxide during desulfurization and regeneration process was studied in the fixed bed reactor. And desulfurization efficiency, mechanical strength and physical properties parameters of semi-coke supported mixed metal oxide were studied. The main conclusions as following: 1. The semi-coke was treated by HNO3, HF and calcined at 800oC under the atmosphere of 2% O2,8% vapor and 90% N2, and the surface area and pore of semi-coke was enlarged greatly. The physical property of modified semi-coke was similarly with that of active carbon, so it could be a good support.2. Supported mixed metal oxide can formed ZnMnO3, (Zn,Mn)Fe2O4 without any other single metal oxide after calcined at 500℃.3. The sulfur capacity and mechanical strength of the supported sorbent contained manganese oxide is much higher than the supported zinc ferrites sorbent. And among the ZFM series, the sulfur capacity and mechanical strength of sample ZFM0.6 in which the molar ratio of ferrite, zinc and manganese is 2:1:0.6 is the highest.4. The prepared conditions of sample ZFM0.6/MS were studied in this paper. The results showed that the optimal conditions are calcinations temperature 600oC and the mass ratio of active component and semi-coke is 10:10. The effect of sulfidation temperature on desulfurization efficiency of ZFM0.6/MS sorbent was carried out in 400-550oC, and the results showed that the optimal temperature is 450oC.5. The sulfided ZFM0.6/MS sorbent was characterized by SEM, XRD and N2 adsorption. The results show that pore volume, surface area and pore size declined because ZnS, FeS, Fe7S8 MnS and Mn2S3 were formed during sufidation, illustrated by XRD characterized. The result inproves that sulfidation is"obturating pores process".6. The desulfurization efficiency of sample AC28 prepared under the optimal conditions was carried out in 450oC. The results showed that the desulfurization time reaches 41h. Moreover, the mechanical strength is more than 30N/cm. So the sample AC28 would be an ideal recycle sorbent from the aspect of high sulfur capacity and mechanical strength.7. The regeneration for AC28 sorbent was carried out at 650oC at the atmosphere of 4% O2, 6-8% H2O and N2 as balance gas, space velocity of 2400h-1.With the regeneration time increase, the chemical reaction slowed down because sulfur contained in sorbent decreasing. After three cycles of sulfidation and regeneration, the sulfur capacity and mechanical strength has little changes which proved that sorbent AC28 could be a good desulfurizer for repeated use.8. The different sorbents (fresh, sulfided and regenerated) for AC28 were characterized by XRD and XPS. Compared with the fresh one,the position and shapes of diffraction peaks in the XRD patterns of AC28 changed slightly after three regenerations. It indicates that the structure of the sorbent after regeneration was similar to that of flesh one.The XPS results show that binding energy of metal oxide of fresh and regenerated sorbents hardly changed. So the sulfidation and regeneration processing is feasible for AC28 sorbent. |
