The effect of graphitization on methanation

Kowalczyk et suggested that the activated carbon was treated in pure argon flow at 1,300°C for one hour (AC1300) or in pure argon flow at 1,900°C (AC1900) for 2h, then washed by water and dried at 120°C for 5h. The surface properties of the activated carbon after treatment were measured with N2 adsorption and high-pressure mercury method respectively as shown in Table 6.50. 

It can be seen from Table 6.50 that the total micro-pores volume (Vqdr) changes slightly at 1,300°C, while the Vodr changes from 0.33 to 0.036cm g at 1,900°C, and forms a kind of surface structure called as turbulent structure. Therefore, the micro-porous surface area (Sdr) is decreased from 890m to 62m g  

The average pore size (ron) is increased from 0.74 nm to 1.16 nm. The M-Ru/AC catalyst promoted by Ba or K was prepared by the activated carbon treated at 1,900°C, the conversion of activated carbon transform to methane in the H2 flow (0.5ml -s ) for 24h is shown in Table 6.51. 

It can be seen from Table 6.51 that Ba promoter significantly inhibits the methanation of the activated carbon, the conversion drop s from 21.8% to 3.2%, while K promoter is beneficial of the methanation and the conversion increases from 21.8% to 35.6%. The possible reason is that BaO partly covers ruthenium particles so that prevents the CHx shifting towards ruthenium particles. 

Forni L et al selected two kinds of activated carbons and one is pure activated carbon (G) which was made by coconut shell and treated respectively in the inert gas flow at 1,900°C or 2,000°C for 2h. The sample treated at 1,900°C was calcined at 425° C in air flow for 12 h, then at 900°C in H2 for 3h. These samples are 

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