Study On Highly Effective Direct Decomposition Of H₂S Into H₂ And S By Microwave Catalysis And Its Microwave Catalytic Effects

Hydrogen sulfide is a highly toxic,odorous,and corrosive gas,which is generated from a variety of large-scale petroleum hydrorefining and natural gas purification processes.At present,the main industrial technology for removing H₂S is the Claus Technology,that is,H₂S is not completely oxidized to produce sulfur and water.However,this method requires extremely high reaction temperature?such as 1300 K?and also produces a large number of toxic by-products?H₂S or SO₂?,causing secondary pollution.Although sulfur is recovered,it converts precious hydrogen into water,causing a great waste of hydrogen resources.If H₂S can be directly decomposed into H₂ and S,and H₂ from H₂S decomposition reaction can be used directly in industrial hydrogenation and other processes.It not only solves the environmental pollution problem but also brings economic benefits.Therefore,it is of great significance for highly efficient H₂and valuable S production from direct decomposition of H₂S.However,the direct H₂S decomposition reaction is limited by thermodynamic equilibrium,and the H₂S conversion is extremely low even at a relatively high reaction temperature.Furthermore,the decomposition of H₂S is kinetically sluggish with the apparent activation energy as high as 495.62 k J/mol.In this paper,our group proposed a new method for highly effective direct decomposition of H₂S by microwave catalysis to solve the above problems,and explored new microwave catalysts with high activity and stability.In addition,the catalysts were characterized and analyzed by XRD,SEM,?HR?TEM,Raman,XPS,FT-IR and BET.The research conclusions are as follows:?1?The Mo₂C and Mo₂C-Ti O₂ catalyst were prepared by temperature programmed reduction procedure method.It is found that Mo₂C-Ti O₂ microwave catalyst has high activity.The H₂S conversion is highly up to 99.9%at 750?,which greatly surpasses the corresponding H₂S equilibrium conversion in the conventional reaction mode.In addition,Furthermore,the apparent activation energy of the Mo₂C and Mo₂C-Ti O₂microwave catalysts decrease to as low as 18.2 k J/mol and 16.8 k J/mol under microwave irradiation.?2?The Mo₂C-Co₂C/Si C@C microwave catalyst was prepared via in-situ microwave carbonization.It is found that Mo₂C-Co₂C/Si C@C microwave catalyst has high activity and stability.the H₂S conversion is highly up to 90.3%at 750?,which greatly surpasses the corresponding H₂S equilibrium conversion in the conventional reaction mode.Moreover,the H₂S conversion at 650?does not show any visible change after tested for 300 min.In addition,Furthermore,the apparent activation energy of the Mo₂C-Co₂C/Si C@C microwave catalyst decreases to as low as 14.9k J/mol under microwave irradiation.?3?The Mo₂N-Mo C@Si O₂ microwave catalyst was prepared by in-situ synthesis.It is found that the Mo₂N-Mo C@Si O₂ microwave catalyst has high activity and stability.the H₂S conversion is highly up to 96.3%at 750?,which greatly surpasses the corresponding H₂S equilibrium conversion in the conventional reaction mode.Moreover,the H₂S conversion at 650?does not show any visible change after tested for 6 h.In addition,Furthermore,the apparent activation energy of the Mo₂N-Mo C@Si O₂ microwave catalyst decreases to as low as 16.9 k J/mol under microwave irradiation.?4?It is found that microwave catalysis can break the chemical equilibrium limitation of the H₂S decomposition reaction,which displays a significant microwave selective catalytic effect.In addition,microwave irradiation can reduce the apparent activation energy of the H₂S decomposition reaction,which suggest a remarkable microwave direct catalytic effect.