What is carbon emission and what harm does it do? How can carbon dioxide be prevented?
Carbon deposition reaction:CH4 = kJ/mol C+H274.92CO = CO2+C +172.4 kJ/mol on.The main cause of carbon analysis is that the ratio of water to carbon is too low, so that the rate of carbon removal is lower than the rate of carbon depositionThe above chemical reactions are reversible reaction, from the analysis of thermodynamics, if the increase in temperature or reducing system pressure, increase the possibility of methane decomposition reaction type is CH4 C+H2 produce coke; possibility of CO reaction 2CO = CO2+C and CO = C + H2 reaction +H2O produce coke decrease. If the temperature is reduced or increased the pressure is on the contrary. The effect of temperature on coke reaction is very large, to avoid the [wiki] [/wiki] carbon catalyst must select the appropriate temperature, avoid carbon deposition area.
The thermodynamic partial oxidation to synthesis gas, there is a relationship between O2 and CH4 mole ratio on deposition temperature, in the actual production is done, according to raw materials the ratio of the different temperature conditions of the appropriate choice, or according to the different ratio of raw materials, select the appropriate reaction temperature, to minimize coking of the catalyst.According to the metal partial oxidation of methane to Syngas in the catalyst, at different temperatures of pure CH4 and CO in nickel catalyst coke rate, found under the temperature of 1123K, 2CO is CO2+C rate than methane dissociation rates were slow 20 times and 5 times, which indicates that the catalytic pyrolysis of methane is the main way to deposit formation.
They also believe that the mechanism of independent coking causes and synthesis gas generation, through the use of appropriate catalyst can avoid from kinetics of coke.It is found that the effect of catalyst by coke gas ratio of material. In 750 degrees, when n (CH4): n (O2) = 2, the catalyst produces a large amount of coke; when n (CH4): n (O2) = 1.75, the catalyst activity is low, but no coke formation; when n (CH4) n (O2) =1.78, the coke on the catalyst surface to achieve single steady-state distribution, almost no decrease of catalyst activity; continuously for 50 hours at 800 DEG C, and the catalyst is very stable.Prevention: 1., the temperature should not be too high, 2. water carbon ratio to a reasonable 3, to ensure the quality of the catalyst
