Analysis of sulfur compound types in asphalt

Abstract

Sulfur compound types were determined in asphalts from the SHRP Materials Reference Library. Sulfoxides were determined by infrared spectrophotometry (IR); sulfides were measured via oxidation to sulfoxides with tetrabutylammonium periodate followed by I R thiophenes were determined by difference (total sulfur minus other types). Compound types were determined in whole asphalts as well as for fractions from each asphalt obtained using nonaqueous ion exchange liquid chromatography (NIELC). Results from the individual NIELC fractions were compared against those for the corresponding whole asphalt. In addition, results from this analysis were compared against those obtained by other workers utilizing X-ray (XANES) techniques. The neutral fraction from NIELC was further fractionated into saturated hydrocarbon, neutral-aromatic (contains thiophenic sulfur types), and sulfide classes using liquid chromatographic (LC) techniques. The distribution of sulfur types obtained from the LC separation of neutrals was compared with that obtained from the above instrumental methods. Generally, results from the IR-oxidation techniques were in good agreement with those from LC separations and XANES analysis, except that the latter include aromatic or other sulfide types in with total sulfides, whereas the oxidation-IR approach appears to be specific for aliphatic sulfides, per se. Considerable variation of sulfur types within NIELC fractions was observed. Compounds with one or more acidic groups plus a sulfoxide group constitute a significant proportion of the total amphoteric compounds present in most asphalts.

The oxidation of bitumen witnessed in-situ by infrared spectroscopy

“…On the other hand, in the studies of changes in Molecular Weight Distribution (MWD) upon oxidation by air analyzed with Gel Permeation Chromatography, it is well documented that the MWD becomes bimodal. While this may be due to the agglomeration of molecules with increased polarity, it is thought to also indicate that oligomerization is 3 and Cu (BFeCl 3 Cu) (up) and bitumen with Cu (BCu) (down), during exposure to air at 163°C measured by ATR-FT-IR as compared to the spectra at the previous time step occurring in the bitumen upon oxidation parallel to a settled uptake of singular molecules of oxygen into the mass [38][39][40]. However, examining the step differential spectra we clearly see that the oxidation of bitumen is a stepwise reaction (Fig.…”

“…This phenomenon has been observed [38][39][40], but suggested as originating from unspecified form of elimination reaction releasing a water molecule [46]. A dimerization of carboxylic acids was proposed for a model.…”

Determination of oxygen and nitrogen derivatives of polycyclic aromatic hydrocarbons in fractions of asphalt mixtures using liquid chromatography coupled to mass spectrometry with atmospheric pressure chemical ionization

“…The maltenic fraction remained soluble in isooctane and was separated by filtration. The maltenic fraction was separated into acidic, basic, and neutral fractions using the method of Green by nonaqueous preparative ion exchange chromatography .…”

Base program on energy related research. Quarterly progress report, August--October 1995

“…The task activities to reach this objective are to (1) archive spill test facility results fi-om the National Liquefied Gaseous Fuel Spill Test Facility, hereafter called Spill Test Facility (STF), (2) update the data base on spill control technology documents and data, (3) archive and monitor literature for significant hazardous spill incidents, and (4) transfer this information to Clean Air Act Amendments (CAAA) participants of the U.S.…”