Heptane soluble and -insoluble fractions

Thermooxidative and Photooxidative Aging of Polypropylene Separation of Heptane-Soluble and -Insoluble Fractions... 

Fractionation by solubility is used to isolate asphaltenes from maltenes, and the standard method (ASTM-3279-97) has been used in this work. Crude petroleum is mixed with 40 volumes of heptane, heated, stirred, and left to cool. The asphaltenes form a precipitate that can be removed by filtration. Normal practice is to clean the asphaltene fraction by Soxhlet in heptane. The proportions of asphaltene in crude petroleums vary widely, from less than 0.1% in the best crudes to over 10% in the heavy crudes. In general, the heavy crudes such as Maya are of most interest. The solubility of petroleum asphaltene in NMP is of interest since the NMP-insoluble material has no fluorescence [61] and was initially assumed to be aliphatic. However, it has UV absorbance and must be aromatic [62]. The separation into NMP soluble and insoluble was achieved for several asphaltenes. A Kuwaiti asphaltene was separated into NMP-soluble and -insoluble fractions [63]. Seven crude oils were fractionated into heptane solubles and asphaltenes for comparison with an asphaltene from a heavy oil [64]. 

Fig. 12. I3C NMR spectra of boiling heptane-soluble and boiling pentane-insoluble fraction of polypropylene prepared with (a) 6-TiCl3-Al(13CH3)2I (b) 6-TiCl3-Al(13CH3)3-Zn(nCH3)2 (c) 6-TiClrAl(l3CH2CH3)3-Zn(13CH2CH3)2. The asterisked resonances are due to 13C-enriched carbons of the end-group.

The selective deactivation of atactic centers appears to be the most important advantage to be gained from using alkoxy silanes as external donors. Our findings on the microstructure of unfractionated and fractionated polypropylene show that the most atactic centers are deactivated first, after which deactivation is in the order of increasing isotacticity. A clear increase in isotacticity of both the boiling heptane soluble and boiling heptane insoluble fractions was observed when external donor was added. 

Following the same procedures described in the above-mentioned study, additional extractive data were obtained for the epoxy phenolic enamel that was irradiated at 4.7-7.1 Mrad at 25 and — 30 °C in the presence of distilled water, 3% acetic acid, and n-heptane. The changes in the amount of extractives resulting from the irradiation treatment are shown in Table IX. In the case of the water and acetic acid extractives, there was no change in either the chloroform-soluble fractions or the chloroform-insoluble fractions. In the case of the n-heptane extractives, the amount of extractives decreased when the irradiation temperature was reduced from +25 to — 30°C. Infrared spectra of the chloroform-soluble residues from the water and acetic acid extractives of the unirradiated and irradiated enamel were identical to the chloroform-soluble residues from the solvent blanks. In other words, the epoxy phenolic... 

The addition of a mixture of monomers and catalyst to a suspension of zinc chloride in benzene or heptane gives 56 and 77% yield, respectively, of methanol-insoluble product containing ca. 57 mole % of acrylonitrile in both cases. Extraction of the product from the reaction carried out in heptane gave 8% of a DMF-soluble fraction which contained 90.9 mole % acrylonitrile and 92% of a DMF-insoluble fraction which contained 52.8% acrylonitrile, close to the theoretical value for an equimolar copolymer. In addition, the reaction mixture gave a 3.9% yield of a methanol-soluble fraction which contained 28.5 mole % acrylonitrile. 

Therefore, in a mixture as complex as petroleum, the reaction processes can only be generalized because of the difficulties in analyzing not only the products but also the feedstock as well as the intricate and complex nature of the molecules that make up the feedstock. The formation of coke from the higher molecular weight and polar constituents of a given feedstock is detrimental to process efficiency and to catalyst performance. One method by which the process chemistry can be rationalized is to separate the resid and its conversion products into fractions using solubility/ insolubility in volatile liquids as well as adsorption/ desorption on solids. In this way a number of resids and resid conversion products were separated into coke (toluene insoluble), asphaltenes (toluene soluble/ n-heptane insoluble), resins (n-heptane soluble, adsorbs on alumina), aromatics (n-heptane soluble, does not adsorb on alumina), and saturates (n-heptane soluble, does not adsorb on alumina). 

The asphaltene constituents produce the highest amount of coke (relative to the other fractions of the resid). The formation of a coke-like substance during resid upgrading is dependent on several factors 1) the degree of polynuclear condensation in the feedstock 2) the average number of alkyl groups on the polynuclear aromatic systems and 3) the hydrogen-to-carbon atomic ratio of the pentane-insoluble/heptane-soluble fraction. 

Changes in Molecular Weight and Its Distribution The thermal oxidation of the ether-insoluble heptane-soluble fraction of the atactic... 

TMC-2 and TMC-3), and catalyst containing an internal and external donor (TMC-4). Polymers obtained with these catalysts have been fractionated into three fractions PP5, atactic fraction soluble in boiling pentane PP7, stereoblock fraction soluble in boiling heptane and IPP, isotactic fraction insoluble in boiling heptane. Cp and kp values have been calculated for separate fractirais to account for the content of every fractiOTi in the total polymer. 

The initial work with this instrument in the Chemical Engineering Department of Imperial College involved the comparison of fractionations of four petroleum residues by TLC, column chromatography, and heptane-soluble/insoluble fractions [36]. The mass spectra of the residues and the heptane-insoluble fractions indicated an upper mass limit of about m/z 2000 for the whole samples and about m/z 10,000 for the residues, showing the mass discrimination against the high-mass components of the asphaltene fractions. The use of preparative and analytical SEC to produce narrow time-elution fractions of coal tar pitch by three separate experiments [37], with measurement of the SEC elution times of the fractions on the analytical column and measurement of the Mp values of the fractions by MALDl- and LD-MS, showed that these mass and elution time values, when plotted with the standard polystyrene masses and elution times, corresponded to the same line. This... 

Solvent solubility has been used to separate coal tar pitch [65] into heptane solubles, heptane insolubles but toluene soluble (asphaltenes), and toluene insolubles (preasphaltenes). The same pitch was separated into acetone-soluble, pyridine-soluble, and pyridine-insoluble fractions [66]. The same pitch, a coal digest, and a low-temperature coal tar were similarly fractionated [67,68]. 

This section summarizes the data of Karaca et al. [65]. The pitch was fractionated by solvent solubility into heptane solubles, toluene solubles, and toluene insolubles in the weight ratio 14.4%, 44.4%, and 41.2%, respectively. The elemental composition of the pitch is listed in Table 33.1 and the fraction weights are listed in Table 33.2. 

FIGURE 333 LD-MS mass spectra of pitch fractions. (A) The heptane solnbles in linear TOP mode at laser powers shown (pitch heptane soluble [PHS] linear) (B) the heptane solnbles in reflector TOP mode at 40% laser power (PHS reflectron) (C) the toluene solnbles in linear TOP mode at the laser powers shown (pitch tolnene solnble [PTS] linear) and (D) the toluene-insoluble fraction in linear TOP mode at the laser powers shown (pitch tolnene insolnble [PTI] linear) ( thick sample layer) (E) LD-MS of pitch pyridine insolubles. Graphs are of ion count or intensity or arbitrary intensity versus mass (m/z). Figures parts (A-D) from Karaca et al. [65] copyright John Wiley Sons 2009 part (E) from Millan et al. [66] copyright John Wiley Sons 2005, reproduced with permission. 

FIGURE 33.6 Maya fractions considered to represent probably the best mass spectra with (laser power%/HMA voltage kV) 1, heptane solubles (50%/9) 2, asphaltenes (50%/7.5) 3, NMP-soluble asphaltenes (40%/7.5) 4, NMP-insoluble asphaltenes (40%/8). Data from Morgan [75] and Herod et al. [77]. 

A terpolymer of TMO-PO-AGE was also made by the same general procedure used in the large scale TMO-AGE work (Run 7, Table II). The terpolymer was isolated in two fractions of similar composition (ca. 60% PO and 10% AGE), but different solubility, and different molecular weight. The highest molecular weight fraction was heptane-insoluble, confirming that TMO units contribute substantial heptane-insolubility. 

The increase in size of the syndiotactic rrrr pentad peak of the boiling heptane soluble fractions was unexpected in view of the decrease in the rrrr pentad of unfractionated PP and the boiling heptane insoluble fraction (see Fig. 6). One possible explanation of this apparently unreasonable result is the following an external alkoxy silane donor preferentially deactivates active centers that produce mainly atactic polymer while leaving active those centers that produce mainly short chain syndiotactic polymer. Simultaneously there is an increase in the production of isotactic polymer with some stereochemical defects, but... 

After polymerization, a fraction of the polymer remains in solution in heptane. The insoluble polymer is extracted 2 hours by boiling heptane in a Kumagawa. The heptane insoluble fraction is expressed (in percent) as the ratio of the insoluble polymer to the whole polymer (including cold and hot heptane soluble). 2 hour Kumagawa extraction is equivalent on a powder to 24 hour Soxhlet extraction. 

Analysis. The polydispersity and Hw of all the heptane insoluble/octane soluble and octane insoluble fractions were determined by gel permeation chromatography (GPC) in o-... 

It must be said that the e/t values of the octane insoluble fractions are evaluated with a higher error than those of the octane soluble ones and of the heptane insoluble fractions. 2 Indeed, due to the high molecular weight and to the high first step stereoregularity of these fractions, the smaller peak of the erithro resonance, in some cases, can be hardly detected. 

We have reported homopolymerization of propylene and its copolymerization with ethylene using catalyst 4/MAO systems [92]. Isotactic polypropylene obtained with catalyst 4/MAO catalyst systems in the range of reaction temperature from —30°C to 50°C was successively fractionated by boiling pentane, hexane, heptane, and trichloroethylene. It was found that the hexane-insoluble/heptane-soluble portion was the major fraction for all samples. The whole and fractionated polymers were characterized in comparison to those obtained with MgCl2/TiCl4-Et3Al catalyst system by NMR, GPC, and DSC. The C NMR spectrum of the Zr system exhibited a number of... 

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