Silica deasphaltened bitumens

The separation scheme for deasphaltened bitumen on silica [WOELM, activated at 140°C (4 hr)] is shown in Figure 1. The fractions obtained were loosely termed hydrocarbons. Polar I, II, and III. The IR spectra of these fractions, as shown in Figure 2, suggested that Polar I was very similar to the polyaromatic/neutral polar fraction from the API 60-based separation after removal of additional material from alumina with pure benzene. Also, simulated distillation curves for this fraction from either procedure are very similar (Figure 3). The IR spectra of the Polar II and III fractions show the presence of all the functional groups which can be distinguished in these complex mixtures and which... 

Figure 1. Separation of deasphaltened bitumen on silica and of Polar I fraction on alumina. The numbers in brackets are % of sample those outside...

Table I summarizes the analytical results for deasphaltened Athabasca bitumen (without prior distillation) on a series of columns used in the USBM-API 60 procedure, and those obtained by the simplified silica and alumina class separation scheme. As seen, the results are comparable provided that the polyaromatic and polar fractions are combined. The total analyses of the separated fractions obtained by the two methods listed in Table II are also in good agreement, with the exception that sulfur values from the simplified procedure are somewhat higher in all aromatic fractions except the polyaromatic/polar fraction.

---