کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1420022 986078 2006 10 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Fractionation of pitches by molecular weight using continuous and semibatch dense-gas extraction
موضوعات مرتبط
مهندسی و علوم پایه مهندسی انرژی انرژی (عمومی)
پیش نمایش صفحه اول مقاله
Fractionation of pitches by molecular weight using continuous and semibatch dense-gas extraction
چکیده انگلیسی

A countercurrent, multistage, dense-gas extraction technique with reflux was investigated for the fractionation of carbonaceous pitches. Two modes of operation were investigated: continuous-stripping and semibatch operation. For example, continuous stripping with dense-gas toluene in the supercritical state, a positive column temperature gradient from 330 to 380 °C, and a pressure of 49 bar was used to strip the monomer and dimer species from an A-240 petroleum pitch feed, yielding a high molecular weight (mol wt) bottoms product rich in trimer and higher oligomers. Afterwards, semibatch operation was used with supercritical, dense-gas toluene, a temperature gradient of 330 to 380 °C, and pressures from 84 to 111 bar to fractionate the above bottoms product, yielding a trimer-rich overhead (average mol wt (Mw) = 800) and a tetramer and higher residue with Mw ∼ 1000. Considering the two operations as a unit, a combined selectivity factor of ∼350 was obtained. Not only is this at least an order of magnitude better than what can in principle be accomplished by conventional, single-stage solvent extraction, but such extraction is inapplicable to our system because of the insolubility of the pitch fractions of interest in typical liquid solvents. Matrix-assisted, laser desorption/ionization time-of-flight mass spectrometry (MALDI) was used to verify that separation was indeed occurring by mol wt and to study the relationship between the Mw, softening point, and C/H ratio of the fractions produced.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Carbon - Volume 44, Issue 2, February 2006, Pages 243–252
نویسندگان
, ,