| 초록 |
In general,SOx emission problem has been caused by H2S released from crude oil and natural gas refineries. Hydrogen sulfide from stationary source is usually recovered as elemental sulfur by the Claus process. Unfortunately about 3-5% of sulfur compounds is discharged due to thermodynamic limitations of Claus reaction. For this reason various tail gas treatment(TGT) technologies have been proposed. Most of wet Claus TGT processes involve hydrogen sulfide absorption step into an alkaline solution. In the same manner, H2S contained in the coke oven gas of the steel smelting process is scrubbed and concentrated using aqueous ammonia solution. The concentrated H2S separated from ammonia solution is generally transferred to the Claus plant, and remaining aqueous ammonia solution is incinerated without further treatment. Since the separation of H2S is not perfect, the remaining aqueous ammonia contains about 2% of H2S which in turn can cause the SOx emission problem during incineration. Hence, new technologies are being examined to remove H2S in excess water and ammonia stream. One approach is the selective catalytic oxidation of H2S to elemental sulfur and ammonium thiosulfate (ATS: (NH4)2S2O3) as reported in our previous work. ATS has been used in photography and agricultural application. Commercial processes currently practiced for its mass production are mainly based upon the direct reaction of ammonium sulfite (AS:(NH4)2SO3) with excess sulfur at 85-110℃. Alternative synthesis method is an aqua-ammonia base system. Sulfur dioxide from the incineration of Claus tail gas is absorbed in aqueous ammonia solution to form ammonium sulfite and ammonium bisulfite (ABS: NH4HSO3) in aqueous ammonia solution. Then H2S gas is sparged into the reactor and reacts with mixture of AS and ABS to produce ATS. Therefore, this new vapor phase process for the conversion of H2S to ATS and sulfur seems to offer an advantage of simple operation.In this study, we examined the performance of V-Bi-O/TiO2 catalyst for the selective oxidation of H2S in the stream containing both of ammonia and water. Kinetic studies have been carried out to illustrate the reaction path. |
