Study On The Preparation Of Modified Zinc Oxide Based Sorbent And Its Performance Of Removing Sulfide

The chemical production system based on coal gasification and coking technology is an effective way to achieve clean coal utilization.The sulphide containing hydrogen sulfide is the main source of coal gasification,which limits the utilization of coal gas.Therefore,the coal gas desulfurization and purification is very essential.Because of its high desulfurization accuracy,wide temperature range and removing many kinds of sulfides etc,Dry desulfurization technology is widely applied.Due to the complexity of coal gas,the metal oxide sorbents in dry desulfurization appears the phenomenon of sulfur release-the formation of carbonyl sulfide during removing hydrogen sulfide from coal gas.Carbonyl sulfide has a serious impact on subsequent chemical production process.And the general metal oxide sorbent is difficult to remove COS effectively.Therefore,the research on COS reduction in the desulfurization process is very important.Zinc oxide was selected as an active component of desulfurization sorbent and potassium carbonate,alumina as additives,a series of zinc oxide based desulfurization sorbents were prepared by dry mixing.The behavior of removing hydrogen sulfide using zinc oxide based sorbent was discussed in the fixed bed,and the change of COS during the desulfurization was also discussed.The performance of removing hydrogen sulfide using the prepared ZnO based desulfurization sorbents was investigated at 300℃,with gas space velocity of 2000h^-11 and the H₂S concentration of 2000-2500ppm.The results show that:the industrial active ZnO series desulfurization sorbents has the short breakthrough time,and the low breakthrough sulfur capacity;basic zinc carbonate decomposed of active ZnO series desulfurization sorbents has the longer breakthrough time,and has the higher sulfur capacity.Among them,the basic zinc carbonate decomposed active Zn O is the component,by adding pseudoboehmite decomposed ofγ-Al₂O₃ and K₂CO₃ additives,the prepared zinc oxide based desulfurizer has better desulfurization activity,and the breakthrough sulfur capacity reaches 12.18%.The influence factors of COS formation during the gas phase reaction were investigated under the conditions of 300℃,with the gas flow rate is 500ml/min and in the blank pipe.The results show that:the reaction of between CO and H₂S plays a major role in the formation of COS.The quartz tube itself catalyzes the reaction of CO and H₂S,leading in the formation of COS.The composition of CO₂ and H₂ at reaction atmosphere has little effect on the formation of COS.The performance of COS removal for the zinc oxide based desulfurization sorbents was investigated under the condition of 300℃,with gas space velocity of 2000h^-1 and the COS concentration of 1000-1500ppm.And the changes of COS in the process of H₂S removal using Zinc Oxide based desulfurizers were investigated under the condition of 300℃,with gas space velocity of 2000h^-1 and the H₂S concentration of 1000-1500ppm,with the CO or CO₂.The results show that:the modified zinc oxide desulfurization sorbent can remove COS to a lower concentration,and the modified zinc oxide based desulfurizers has conversion and absorption effect on COS removal.At the atmosphere containing CO or CO₂,the formation of COS using modified zinc oxide based desulfurizers during removing hydrogen sulfide.The desulfurization product ZnS promotes the formation of COS,mainly through the reaction between Zn S and CO/CO₂ to form COS.The influence of atmosphere effect on the formation of COS in modified zinc oxide based desulfurizer desulfurization process was discussed.The results show that:when H₂ and CO coexist in the reaction atmosphere,H₂ inhibits the formation of COS.when H₂ and CO₂ coexist in the reaction atmosphere,H₂ promotes the formation of COS.When the reaction atmosphere with the H₂O,the existence of H₂O reduces the formation of COS to some extent.