Heptane insoluble

The heptane insoluble (ASTM D-3279) method is commonly used to measure the asphaltene content of the feed. Asphaltenes are clusters of polynuclear aromatic sheets, but no one has a clear understanding of their molecular structure. They are insoluble in C3 to paraffins. The amount of asphaltenes that precipitate varies from one solvent to another, so it is important that the reported asphaltene values be identified with the appropriate solvent. Both normal heptane and... 

Although PFE lacks a proven total concept for in-polymer analysis, as in the case of closed-vessel MAE (though limited to polyolefins), a framework for method development and optimisation is now available which is expected to be an excellent guide for a wide variety of applications, including non-polyolefinic matrices. Already, reported results refer to HDPE, LDPE, LLDPE, PP, PA6, PA6.6, PET, PBT, PMMA, PS, PVC, ABS, styrene-butadiene rubbers, while others may be added, such as the determination of oil in EPDM, the quantification of the water-insoluble fraction in nylon, as well as the determination of the isotacticity of polypropylene and of heptane insolubles. Thus PFE seems to cover a much broader polymer matrix range than MAE and appears to be quite suitable for R D samples. 

Carbene the pentane- or heptane-insoluble material that is insoluble in benzene or toluene but which is soluble in carbon disulfide (or pyridine). 

Figure 3. Change in ar and Oqh with reaction severity (ref. 19 subbituminous coal ) heptane-insoluble product fraction.

Sources Speight (1981), Yen (1973), and Chevron (unpublished data). b Ar atmospheric resid. c 1000°F + vol % of atmospheric resid. d Heptane insoluble. 

Another method, not specifically described as an asphaltene separation method, is designed to remove pentane- or heptane-insoluble constituents by membrane filtration (ASTM D-4055). In the method, a sample of oil is mixed with pentane in a volumetric flask, and the oil solution is filtered through a 0.8-p.m membrane filter. The flask, funnel, and filter are washed with pentane to completely transfer any particulate matter onto the filter, after which the filter (with the particulate matter) is dried and weighed to give the pentane-insoluble constituents as a percent by weight of the sample. Particulate matter in the extracts can also be determined by membrane filtration (ASTM D-2276 ASTM D-5452 ASTM D-6217 IP 415). 

ASTM D-3279. Standard Test Method for n-Heptane Insolubles. 

ASTM D-6560. Standard Test Method for Determination of Asphaltenes (Heptane Insolubles) in Crude Petroleum and Petroleum Products. 

There are several possible flow scheme variations involved for this process. It can operate as an independent unit or be used in conjunction with a thermal conversion unit (Figure 9-25). In this configuration, hydrogen and a vacuum residuum are introduced separately to the heater, and mixed at the entrance to the reactor. T o avoid thermal reactions and premature coking of the catalyst, temperatures are carefully controlled and conversion is limited to approximately 70% of the total projected conversion. The removal of sulfur, heptane-insoluble materials, and metals is accomplished in the reactor. The effluent from the reactor is directed to the hot separator. The overhead vapor phase is cooled, condensed, and the hydrogen separated from there is recycled to the reactor. 

Effect of Coal Rank and Solvent Source on Conversions and Heptane-Insoluble Product Compositions... 

Comparison of analyses of heptane insolubles from the liquefaction of Monterey bituminous and Wyodak subbituminous coals in the hydrogen-enriched solvent shows that carbon, hydrogen and oxygen concentrations converge with increasing reaction severity to form a product with similar elemental analyses. The same convergence is seen when the hydrogen-depleted solvent is used. 

Primary coal liquefaction products from three processes— solvent-refined coal, Synthoil, and H-Coal—were hydrotreated. Upgrading was measured in terms of the decrease in heptane and benzene insolubles, the decrease in sulfur, nitrogen, and oxygen, and the increase in hydrogen content. Hydrotreating substantially eliminated benzene insolubles and sulfur. An 85% conversion of heptane insolubles and an 80% conversion of nitrogen was obtained. Catalyst stability was affected by metals and particulates in the feedstocks. 

This chapter reports results of applying a catalytic hydrorefining process to four coal liquids solvent-refined coal (SRC) process filter feed, SRC extract product, Synthoil, and H-Coal process hydroclone underflow. The achieved upgrading is evaluated in terms of reduction in benzene and heptane insolubles, reduction in sulfur, nitrogen, and oxygen, an increase in hydrogen content, and a yield of lower boiling products. 

Hydrotreatment was carried out over a commercial UOP black oil conversion catalyst in bench-scale units of 200-800 mL catalyst capacity. Temperature range was 375°-450°C and the pressure range was 2000-3000 psig. Weight hourly space velocity (WHSV) varied from 0.1 to 1.0 depending on the heptane-insoluble content of the feed. A flow diagram of a typical plant is shown in Figure 1. The stripper bottoms usually... 

The dimethylformamide (DMF)/xylene insolubles, assumed to represent ash and unconverted coal, were eliminated substantially. The benzene and heptane insolubles in the feed, adjusted to an ash plus unconverted coal free basis, were reduced substantially and the ASTM ash dropped from 4% to 0.1%. The SRC content of the filtrate, defined as percentage 850°F+ bottoms was 29%, as compared with 30.3% in the feed after correction to an ash plus unconverted coal basis. 

The heptane-insoluble content of the composite product was 9.76%, representing an 89% conversion. The variation of heptane insolubles with time is shown in Figure 2. Initial conversion of heptane insolubles was 94% while final conversion was 86%. 

H-Coal hydroclone underflow was supplied by Hydrocarbon Research, Inc. It contained 9.09% ash and required filtration. Because of the relatively high viscosity of the stock, filtration was difficult, and only a limited amount of hydrotreater feed was prepared. Inspections are given in Table V. Thermal and atmospheric exposure during filtration downgraded the stock. The benzene and heptane insolubles in the product were substantially higher than those in the feed, when corrected to an ash plus unconverted coal free basis. The filtrate still contained 0.12% ash. 

A 178-hr hydrotreating run was made, during which the heptane-insoluble conversion dropped 10%. Results obtained at 54-78 hr on stream are given in Table II. Mass balance, chemical analysis, and fractionation gave the fuel product and hydrogen distributions shown in Table III. 

Table VI recapitulates the relative response of Synthoil and SRC to hydrotreating in terms of percentage conversion of heptane insolubles, as reported in Table II. Conversion of heptane insolubles was substantially greater in the case of SRC. While the Synthoil was processed at a higher space velocity, the throughput rate of Synthoil feed heptane insolubles was only half that of the SRC feed heptane insolubles. Temperature in the Synthoil run was 5°-10°C lower than in the SRC run.

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