Viscosity modification of heavy hydrocarbons using dihydric alcohols

#The present invention relates to the use of dihydric alcohols such as ethylene glycol as viscosity modifiers for heavy hydrocarbons such as asphalt and pitch.

#Petroleum pitch competes with coal tar pitch in many applications where the pitch is used as a carbon source and/or as a binder. The critical properties that are evaluated when deciding what type of pitch to use include: (a) flow properties, as measured by softening point and/or viscosity, and (b) carbon yield, as measured by ASTM D 2488, Coking Value by Modified Conradson Carbon.

#Another pitch property that is also becoming of increasing interest is the polycyclic aromatic hydrocarbon (PAH) content. The U.S. Pat. No. 5,746,906 patent describes a coal tar pitch having a low polycyclic aromatic hydrocarbon content and a method of making such pitch where a high softening point coal tar pitch (softening point of 120–175° C.) was mixed with a low softening point petroleum pitch to make a binder pitch having a softening point of 107–114° C. and a PAH content slightly above 15,000 ppm.

#FIG. 1 is a graph showing effect on the softening point of A-240 pitch for various amounts of various viscosity modifiers for: #6 fuel, ethylene glycol, and dibasic ester (DBE).

#The present invention relates to a method for reducing the viscosity of heavy hydrocarbon materials including, for example, pitch and asphalt type materials. The method involves heating the heavy hydrocarbon material to produce a molten material and dissolving in that molten material in a viscosity reducing amount of at least one dihydric alcohol. In certain preferred embodiments, the heavy hydrocarbon material has a softening point above about 100° C. and in other embodiments above about 120° C. In certain aspects, the present invention, relates to a method where from about 0.5 to about 5%, by wt, and in certain embodiments, from about 0.5 to about 2%, by wt, of the dihydric alcohol is dissolved in the heavy hydrocarbon materials.

#It should be understood that the heavy hydrocarbon materials can include both natural and synthetic pitches and that such materials can be used with the present invention. In certain aspects, the pitches are derived from coal or petroleum are specially preferred.

#Suitable petroleum pitches are obtained, for example, as extraction residues by deasphalting treatment of heavy hydrocarbon oils, such as vacuum residue; residues from products of thermal cracking treatment of heavy hydrocarbon oils; residues from products of catalytic cracking of petroleum fractions; and from products of heat treatment from heavy carbon oils. Suitable coal tar pitches include vacuum bottoms of liquefied coal. Also, both the petroleum and coal pitches produced by using thermal treating or hydrogenating methods can be modified to reduce their viscosity with the method of the present invention.