Carbon molecular sieves from bituminous coal by controlled coke deposition

✍ Scribed by S.N. Vyas; S.R. patwardhan; Bathula gangadhar

• Publisher: Elsevier Science
• Year: 1992
• Tongue: English
• Weight: 744 KB
• Volume: 30
• Category: Article
• ISSN: 0008-6223
• DOI: 10.1016/0008-6223(92)90179-z

✦ Synopsis

Abstr&-Carbon molecular sieves (CMS) and zeolites are widely used as microporous sieving solids for gas and liquid separations. However, due to hydrophobic&y, better thermal stability, and neutrality in both acidic and alkaline media, CM.% have definite advantages over zeolites. In the present work. an effort has been made to develop suitable process conditions for synthesizing CM% from the locally available bituminous coal. The coal was crushed, milled, and agglomerated with sulfate pulp waste liquor (SPWL) or coal-tar pitch (CTP) as the binders, and then carbonized in nitrogen atmosphere at 800°C for about 60 minutes. In order to narrow down the pore mouth sizes, acetylene and benzene were each cracked separately at 800°C to facilitate the deposition of coke on the char. Acetylene and benzene were cracked for 3 to 10 minutes, and IO to 30 minutes, respectively. Acetylene cracked samples did not show good separation, probably because of over-coking in deeper locations. In contrast, benzene cracked samples were found to be highly suitable for CO&H, separation. The best result (i.e., uptake ratio of 39.9) was obtained for feed benzene entrainment in N: of 1.27 x 10 ' g/ml, cracking time of 30 minutes, and this ratio was more than IO times that of non-cocked sample. CMS samples produced using SPWL as binder showed poor Ol/Nz uptake ratios throughout (1 to l.S), whereas samples with C"TP as binder showed Far more encouraging results, the best uptake ratio being 5.5 for benzene-nitrogen feed stream containing 3.508 x 10 J g/ml henzene and 5 minutes cracking time. This ratio is about 5.5 times more than that of uncoked sample.