High-pour-point residuum-containing oils exposed to low temperatures frequently require an additive to keep them from congealing while they are in storage or being transported. Congelation occurs when the waxy component of the oil crystallizes, and the temperature at which congelation is sufficient to stop flow under ordinary conditions is known as the pour point. Additives or substances that are effective for lowering the pour point are called "pour point depressants". Inexpensive pour point depressants which are effective in small concentrations are always sought after. Various pour point depressants are known and have been used reasonably successfully, mostly with middle-distillate fuels. However, it has been found difficult to obtain a potent pour point depressant for high-pour-point oils and residuum-containing oils such as crude oil or shale oil. A further difficulty is that the influence on the pour point of an oil by any particular substance is unpredictable. This unpredictability is generally thought to be due to structural differences of the waxes occurring in the various oils which are derived from different sources or locations. There exists a need for a potent, inexpensive pour point depressant for petroleum residuum-containing oils and shale oils.
USPTO Backgrounds
USPTO Backgrounds