Molecular size characterization of heavy oil fractions in vacuum and solution by molecular dynamic simulation

Abstract

Two kinds of heavy oils were fractionated into eight fractions by Liquid-Solid Adsorption Chromatography, respectively, and samples were collected to measure properties. According to the elemental analysis, molecular weight and 1 H-NMR data, average molecular structures of polycyclic aromatic and heavy resin were constructed with improved Brown-Ladner (B-L) method and several corrections. And then, the most stable conformations of polycyclic aromatic and heavy resin in vacuum and toluene solution were obtained by molecular dynamic simulation, and the molecular size was gotten via the radius of gyration analysis. The results showed that the radius of gyration of polycyclic aromatic and heavy resin was 0.55-0.70 nm in vacuum and 0.60-0.90 nm in toluene solution. With molecular weight increasing, the molecular size in vacuum and toluene solution also increased. Due to the swelling behavior of solvent, the alkyl side chains of heavy oil molecule in solution were more stretched. Thus, the molecular size in toluene solution was larger than that in vacuum.

Influence of Resins on Crystallization and Gelation of Waxy Oils

“…First, 1 g resins were fractioned into resins 1 (R1), resins 2 (R2), and resins 3 (R3) using the solvent systems in sequence: (1) nheptane/benzene (1:1, v/v, 100 mL), (2) benzene (100 mL), and (3) benzene/ethanol (1:1, v/v, 40 mL), benzene (40 mL), ethanol (40 mL). The procedure is outlined in Figure 3 32 The mass fractions of resins 1, resins 2, and resins 3 are listed in Table 2.…”

“…Wax contained in crude oils is generally the normal alkanes, which have carbon numbers ranging from C 17 to C 55 When the oil temperature is above wax appearance temperature (WAT), wax is dissolved in waxy oils.…”

“…Wax contained in crude oils is generally the normal alkanes, which have carbon numbers ranging from C 17 to C 55 When the oil temperature is above wax appearance temperature (WAT), wax is dissolved in waxy oils. When the oil temperature is below the WAT, dissolved wax starts to precipitate out and form wax crystals.…”

Expansion of the feedstock base for the production of diesel fuel by involving the heavy fractions and cold flow improvers

“…The production of high-quality motor fuels is becoming more complicated every year. This is due to the depletion of light oil reserves [4,5], the need to involve into the processing heavier feedstock, as well as the fractions derived from the secondary catalytic petroleum refining. These circumstances most critically affect the production of diesel fuel capable of operating at low temperature environmental conditions as the above mentioned fractions contain high amount of long straight chain paraffins, which are characterized by high freezing points [6,7].…”

GC/MS Analysis of Products from Catalytic Hydroconversion of Dagang Vacuum Residue with Y Zeolite

“…The processing of heavy petroleum can cause serious problems such as rapid deactivation of catalysts, coking within the reactor or fractionator, and formation of sludge in the products. Therefore, understanding composition of heavy oils is necessary for efficient utilization of heavy oils as a basic research [5][6][7].…”