Study On Catalytic Partial Oxidation Of Methane To Syngas

First the catalyst of catalytic partial oxidation of Methane to Syngas in the lab. The affection of carrier, the content of Ni,assistant and the ways of adding assistant to catalyze property and carbon deposition were noticed. At the same time we observed the affection of using Mg, Ca, Zr changing the property of the surface to catalyze property. The result of this experiment indicate: when the controlled temperature is 800℃, the space velocity is 5×105h-1, catalyze property is good if you put 1% Ce and convention rate of methane reaches 94.8%, selectivity of H₂ and Co are 99.5% and 96.2% respectively. So we can say it's beneficial to improve CH₄ convention rate and CO selectivity by doing that. As a result, methane convention rate is closely 95%, selectivity of H₂ and Co is both higher than 90%, but the influence to H₂ selectivity is small. According to the thermodynamics calculating result, whole oxidation is taken place when the temperature is low. As the temperature is higher, the lower residual CH₄ content and H₂0 and CO₂ by –product are, but CO and H₂ productivity are higher. As the pressure is higher, residual CH₄ content and CO₂ and H₂O by-product increase and whole oxidation is taken place often. When the pressure is exactly 1.0, residual CH₄ content is still more than 10% even though the temperature is as high as 850℃, but H₂O or CO₂ are needed to be added to make it convent more. At the foundation of the research of directions of catalyst, Ni-La-Mg/α-Al₂O₃, Ni-La-Ca/α-Al₂O₃ two high-active and high-stability catalysts are designed and researched. At the condition of catalyst is 1g, CH₄/O₂ is 1.90-1.95, the space velocity is 2.1×105h-1, Tm is 870-900℃,the result of the experiment about Ni-La-Mg/α-Al₂O₃ catalyst stability within 500 hours indicate: CH₄ convention rate is always more than 90%, H₂ and CO selectivity are both higher than 95%, and overstock carbon is not found. Hence the catalyst is of longterm stability and less overstock carbon. Through the research of CH₄-O₂-H₂O reaction system, we know if we add steam to oxidation methane the influence of high pressure to reaction system and catalyst can be eliminated. Not only is more methane changed, but also reaction system explosion is avoided under high temperature and pressure because methane is wholly oxidated and temperature of reaction system is controlled efficiently. Besides, adding steam does well to catalyst availability. The reaction mechanism with the aid of impulsion reaction were researched by MS-TPSR ,making the conclusion of following direct oxidation mechanism to make the catalyzed methane though Ni/α-Al₂O₃ to be syngas.