Residual asphalt

Here again, this is not a refining process, properly speaking. Partial oxidation is one of the processes for the ultimate conversion of heavy residues, asphalts, coke and even coal. 

Asphalt (qv) is prepared from petroleum and often resembles bitumen. When asphalt is produced simply by distillation of an asphaltic cmde, the product can be referred to as residual asphalt or straight-mn petroleum asphalt. If the asphalt is prepared by solvent extraction of residua or by light hydrocarbon (propane) precipitation, or if blown or otherwise treated, the term should be modified accordingly to qualify the product, eg, propane asphalt. 

Asphaltenes seem to be relatively constant in composition in residual asphalts, despite the source, as deterrnined by elemental analysis (6). Deterrnination of asphaltenes is relatively standard, and the fractions are termed / -pentane, / -hexane, / -heptane, or naphtha-insoluble, depending upon the precipitant used (5,6,49). After the asphaltenes are removed, resinous fractions are removed from the maltenes-petrolenes usually by adsorption on activated gels or clays. Recovery of the resin fraction by desorbtion is usually nearly quantitative. 

Blown, or oxidized, petroleum asphalts were first produced commercially by Byerley about 1894. But neither blown nor residual asphalts from the early crudes enjoyed very good repute in the United States, partly because of the nature of the crudes and partly because of insufficient care in manufacture. Discovery of sources of asphaltic and semi-asphaltic crudes made possible the production of residual petroleum asphalts suitable for paving, and improvements in the blowing process led to products well suited for the manufacture of prepared roofings. In fact, the early growth of the roofing industry corresponded closely with the production of petroleum asphalts (86). 

Many different feedstocks are employed natural gas (methane, ethane, propane etc., petroleum cuts (Liquefied Petroleum Gas LPG, naphtha, fuel oil, vacuum residues, asphalts etc.), coal, biomass (lignocellulose wastes, wood etc.). 

This type of process can theoretigally be used to treat any gaseous, liquid or solid feed. In practice, however, it is reserved for the conversion of the cheapest raw materials such as hea 7 hydrocarbons (especially fuel oilX and possibly, in the future, petroleum residues (asphalts), coal and biomass (wood). In this case, moreover, the conversion is usually called "gasification. ... 

The development of vacuum distillation provided the means of separating lubricating oil fractions with predetermined viscosity ranges and removed the hmit on the maximum viscosity that might be obtained in distillate oil. Vacuum distillation prevented residual asphaltic material from contaminating lubricating oils but did not remove other undesirable materials such as acidic components or components that caused the oil to thicken excessively when cold and become very thin when hot. 

Asphalt is a product of many petroleum refineries (Barth, 1962) and may be residual asphalt, which is made up of the nonvolatile hydrocarbons in the feedstock, along with similar materials produced by thermal alteration during the distillation sequences, or asphalt may be produced by air-blowing an asphaltic residuum. 

Hydrotreating is being employed extensively in the petroleum industry for processing a variety of feedstocks. Both straight-run and cracked petroleum products such as naphthas, kerosenes, middle distillates, gas oils (atmospheric and heavy vacuum types), cycle stocks, residues, asphalts, crudes, and shale oils may be so treated. The process primarily is employed as a pretreat previous to catalytic reforming or catal3d ic cracking. 

Oil residue asphalt fats Paraffin- or naphtha-based solvent (e.g. kerosene) ... 

May include aged asphalt material, air-blown residue, asphalt fractions, or crude oils. 

Ebullated-bed + deasphalting. H-Oil unconverted bottoms are sent to the SDA unit and separated into a DAO stream and a residual asphalt product. The DAO can either be recycled back to the H-Oil reactor for further conversion and/ or combined with the H-Oil-derived distillates for hydrotreating. The main advantages of this process scheme are the following (Kressmann et al., 1998) ... 

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