Asphaltenes

Asphaltenes: Separations, structural analysis and applications

“…As a result, asphaltene rejection increased with its content [75,77,78] . Ultrafiltration could also greatly reduce permeated density, viscosity and metal contents, which was correlated with permeated asphaltene content [1] .…”

“…In order to fully separate asphaltenes, the volume ratio of solvent to asphaltene should be higher than 40:1. Meanwhile, shorter operation time (less than 8 h) was reasonable, it could avoid to introduce resins into asphaltenes because resin was a less polar and aromatic fraction of oil and similar solubility compared with asphaltenes [1] . Other components may precipitate simultaneously with asphaltenes, like inorganic salts, free radicals, metalloporphyrins, and solvents [67] .…”

“…For instance, the n-pentane-insoluble fraction could be extracted with n-hexane, followed by dealing with hexaneinsoluble fraction with n-heptane, and so on. And about 85% of the inorganic components could be removed just by centrifugation [1] .…”

“…There are mainly two kinds of membranes, inorganic and organic membranes, including zirconia membrane [70] , Ultracel YM and nanopore membrane [71] , asymmetric ceramic monolith membranes [72] , and polyethersulfone and polyimide porous membranes [73,74] , which are widely applied in separation process. Asphaltene was separated experimentally using mica membranes (pore radius 8-220 nm) and Wicke-Kallenback-type diffusion cell in early 1983 [1] . Then asphaltenes from types of Iranian crude oils [75] and Cold Lake oil [76] was successfully isolated by ceramic monolith membranes (pore radius 25-100 nm and 50-700 nm separately), with retention up to 80% for Cold Lake asphaltene.…”

“…Asphaltenes, a complex aromatic molecular mixture, is widely contained in crude oil, residues of petroleum and coal processing. It was firstly adopted asphaltene to indicate the distillation residue of bitumen in 1837 [1] . Fundamental knowledge of asphaltene is gradually enriched due to the development of separation and identification techniques.…”