Study On Adsorption Of Carbonyl Sulfide On Modified Activated Carbon Under Low Temperature

The chemical engineering processes use coal,oil and natural gas as raw materials often produce large amounts of tail gas,which contain a variety of resources that can be used by people,but the trace sulfur impurities will limit the further processing and utilization of these gases.Carbonyl sulfide?COS?is a major organic gas sulfur impurity,low concentration of COS can corrode equipment and pipelines,poisoning precious metal catalysts.COS is difficult to remove due to its relatively stable molecular structure.The COS desulfurizers also face the problem of regeneration in its practical application.Therefore,it is necessary to develop renewable COS desulfurizers with high adsorption capacity at low temperature for the field of industrial desulfurization.In this paper,the activated carbon-based desulfurizer was studied,the low-temperature desulfurization performance and regeneration performance of KOH and metal oxide modified activated carbon were investigated respectively.The structure of desulfurizers were studied by various characterization methods.The main research contents and conclusions are listed as below:1.COS removal ability of activated carbon improved obviously after modified by KOH.With the concentration of KOH immersion liquid increased,the COS breakthrough capacities of desulfurizers increased first then decreased.The activated carbon desulfurizer modified with 10 wt%KOH solution showed best desulfurization performance,COS breakthrough capacity was 40.62 mg/g.The major pore inside the desulfurizer was micropore,the main reaction products of COS on desulfurizer were sulfur and sulfate substances,the oxygen-containing functional groups on the surface of activated carbon may act as oxidants.Investigated the optimal regeneration conditions of KOH modified active carbon desulfurizer.When air purge temperature was 90? and the concentration of KOH solution was 6 wt%during regeneration,the desulfurizer exhibited best desulfurization performance after regeneration.The regeneration performance was excellent after four regeneration cycles,the regeneration rate was 86%.2.Investigated desulfurization ability of several metal-supported activated carbon desulfurizers,the results showed that activated carbon loaded with Ni showed the best COS adsorption capacity.Investigated the influence of preparation conditions on Ni modified desulfurizers,we found that when the loading amount of Ni increased,the COS breakthrough capacity of desulfurizers increased first then decreased,the activated carbon desulfurizer loaded with 30 wt%Ni showed best desulfurization performance,the COS breakthrough capacity was 44.64 mg/g.The major pore inside the desulfurizer was micropore,Ni element on the surface of activated carbon mainly exists in the form of uniformly dispersed NiO and Ni₂O₃,the main reaction products of COS on desulfurizer were sulfate and sulfur,the oxygen-containing functional groups on the surface of activated carbon may act as oxidants.Investigated the influence of calcination temperature on desulfurizer,the optimum calcination temperature was 250?,high calcination temperature would lead to the agglomeration of NiO and Ni₂O₃ grains,when the calcination temperature was increased further,the activated carbon reduced the nickel oxide to nickel simple substance with no desulfurization activity.Investigated the optimal regeneration method of Ni-supported activated carbon desulfurizer,though the regeneration performance of the three-step method is slightly better than that of nitrogen and deionized water method,the performance was still poor after repeatedly regeneration.The regeneration rate was only 21.1%after four regeneration cycles.3.Investigated the influence of reaction conditions on the performance of desulfurizers.Results showed that within a certain range,the COS breakthrough capacity of desulfurizers decreased when the flow rate of feed gas increased,COS breakthrough capacity of desulfurizers increased when the reaction temperature increased.