The effects of hydrogen on KOH activation of petroleum coke

• Published in: Journal of analytical and applied pyrolysis 2012-07, Vol.96, p.120-125
• Main Authors: Xiao, Ronglin, Xu, Shaoping, Li, Qingxue, Su, Yanmin
• Format: Article
• Language: English
• Subjects: Activated carbon; Activation; active sites; adsorption; carbonization; Fourier transform infrared spectroscopy; Hydrogen; nitrogen; petroleum; Petroleum coke; potassium hydroxide; pyrolysis; X-ray diffraction
• ISSN: 0165-2370; 1873-250X
• DOI: 10.1016/j.jaap.2012.03.013

► The effects of H2 on KOH activation of petroleum coke (PC) were investigated. ► The addition of H2 enhanced the porosity development of the activated carbons. ► Additional CH and CH2 on the carbon precursors were formed in presence of H2. ► More K was formed during KOH activation in presence of H2. ► The activation was promoted by reaction of CH and CH2 with potassium compounds. KOH activation of petroleum coke (PC) was conducted with 30vol%H2+70vol% N2 as carrier gas. TG-DTG, FTIR, elemental analysis, N2 adsorption, GC and XRD techniques were used to investigate the effects of hydrogen on the activation. During the initial stage of the activation, i.e. the carbonization of the PC, additional CH and CH2 species were formed due to the chemisorption of hydrogen on the nascent sites of the PC created by the removal of the surface heteroatom groups. The formation of the CH and CH2 species increased the quantity of ‘active sites’ which is favorable to the further activation reaction, and developed the porous structure of the activated carbons. The micropore volume and BET surface areas of the activated carbon prepared under 30vol% H2+70vol% N2 and with a relatively low KOH/PC weight ratio of 2:1 have been increased from 0.78cm3/g and 1936m2/g to 0.97cm3/g and 2477m2/g, respectively, compared to that prepared in pure N2 atmosphere with the same KOH/PC ratio.