| Crude acetylence gas is the tail gas from acetylence production. Because the industrial calcium carbide containing different minerals, it companies a variety of impurty gases in the process of acetylence gas especially H2S and PH3. On one hand, H2S and PH3 may cause the catalyst of polyvinyl chloride (PVC) synthesis poising, and on the other hand, H2S and PH3 are also pose a threat to environment and human health. It is necessary to purfy H2S and PH3 in crude gas. Usually, wet purification was considered as the main method to remove H2S and PH3 simultaneously, but it exsited shortcomings of producing a large amounts of wastewater and difficult recovering the generations. In contrast, dry process did not produce pollutions, but the research was limited in removal of H2S and PH3 alone. H2S and PH3 exisits in actual crude acetylence gas, but it was not studied in simultaneous removal of H2S and PH3 further and systematicly..Aim to above problems and the characteristics of acetylence, SBA-15 was considered as the ideal material which has high selected adsorpotion in simultaneous removal of H2S and PH3. The main research contains four parts:Study on preparation and properties of modified SBA-15 adsorbent; Regeneration performance research of modified SBA-15 adsorbent; Simultaneous adsorption and oxidation kinetics and its reaction mechanism of H2S and PH3.Study on Preparation and properties of modified SBA-15 adsorbent system:The effects of using SBA-15 as carrier, using the traditional hydrothermal synthesis preparation of modified adsorbent, the effects of acid washing, a component type, copper salt precursor, copper loading; modified acid, nitrate content of the second components and types, iron loading and calcination temperature on simultaneous removal of adsorption and oxidation. It also investigated the effect of the addition of three toluene dosage, the type of additives amd ammonium fluoride concentrations for simultaneous of removal of H2S and PH3. Research showed that the adsorbent treated with 10% phosphoric acid,45% copper,8% iron,8% nitric acid,550 degree, which achieved the best adsorption and oxidation properties and the corresponding breakthough adsorption capacity was 31.86mgS/g and 120.05mgP/g respectively. Using 0.5ml trimethlbenzene and 0.1g ammonium to treat the structure of adsorbent, which could develop the adsorption-oxidation activity and the breakthrough adsorption capacity was 55.56mgS/g and 183.79mgP/g.The regeeration performance of modified SBA-15:Experiment was studied on the regeneration of deactivated Cu-Fe/SBA-15 adsorbent and regeneration method, calcination temperature, impregnation concentration and acid regeneration times were investigated. The research showed that the regeneration method of pickling calcinations- acid washing was the best method, the calcination temperature is 450 degree, the concentration of nitrate impregnation was 8%.The adsorption-oxidation kinetics of H2S and PH3 was calculated and analyzed: firstly, using power function as the equivalent dynamics model and analysis and fitting the datas of H2S and PH3 adsorption-oxidation reaction kinetics respectively and achieved adsorption-oxidation kinetics equation was -r= 33×106e-23.44/RTp1.0535p-0.0015 and -r= 2.26×107e-29.442/RTp0.9727p-0.11.Through the relationship two and the deduction of the reaction process, simultaneous kinetic equations was deduced and calculated. The common kinetic equation of simultaneous removal of H2S and PH3 was: -r=3.3×106e-23.44/RTP1.0535p-00015+ 2.26×107e-29.442/RTP0.9727p-0.11.Study on the reaction mechanism of simultaneous adsorption-oxidationof H2S and PH3 on Cu-Fe/SBA-15 adsorbents:according to the evaluation of adsorbent activity and the results of in-situ IR, the reaction mechanism on modified adsorbent for simultaneous removal of H2S and PH3 was proposed:The reaction process can be divided inti three stages:The first stage is the process of adsorption, which was understood that H2S and PH3 reacted with generated NH2- and NH2- groups to fix H2S and PH3 on the adsorbent surface; The second stage is the oxidation stage, the fixed H2S and PH3 was reacted with copper compenents and oxygen which should be oxided to higher valence state and fixed on the surface of materials, such as CuS and P2O5, while the NH2- and NH2" groups will be oxided to No2- and NO3- under the condition of oxygen. The third stage is the inactivation phase, mainly as the reaction proceeds, a reduction of the S2O42- group was generated on the surface of adsorbent, which could hinder further contact bewteen adsorbent and gases. With the amount of group the S2O42- group increasing gradually in the adsorbent, it can result in inactivation of adsorbent eventually. |
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