Petroleum hydrocarbons dispersants

The reactors designed by Phillips Petroleum (now Conoco-Phillips) and UOP produce about 32% and 20%, respectively, of all alkylate produced worldwide (P. Pyror, personal communication). The HF/ hydrocarbon dispersions in these reactors have much larger interfacial areas (probably by a factor of about 10) as compared to areas in sulfuric acid/hydrocarbon dispersions.f This is a major reason why the kinetics of alkylation is much higher with HF. 

Dispersed hydrocarbons in solid minerals and silts in the seas are similar to petroleum hydrocarbons. They are called dispersed petroleum or micro-petroleum. 

UNESCO (1984), Manual for Monitoring Oil and Dissolved/Dispersed Petroleum Hydrocarbons in Marine Waters and on Beaches. 

Traxler, R.W., and L.S. Bhattacharya. 1978. Effects of a chemical dispersant on microbial utilization of petroleum hydrocarbons. In L.T. McCarthy, Jr., G.P. Lindblom, and H.F. Walters (Eds.), Chemical dispersants for the control of oil spills. American Society for Testing and Materials, ASTM STP 659, pp. 181-187. 

In the absence of silica gel, filtration can be used to remove the dispersed oil and grease. In this technique the filtrate, obtained after passing through a 0.45-pm filter paper is left behind on the filter paper. The U.S. EPA uses the term "petroleum hydrocarbons" for dispersed oil and grease. 

Lubricants. Petroleum lubricants continue to be the mainstay for automotive, industrial, and process lubricants. Synthetic oils are used extensively in industry and for jet engines they, of course, are made from hydrocarbons. Since the viscosity index (a measure of the viscosity behavior of a lubricant with change in temperature) of lube oil fractions from different cmdes may vary from +140 to as low as —300, additional refining steps are needed. To improve the viscosity index (VI), lube oil fractions are subjected to solvent extraction, solvent dewaxing, solvent deasphalting, and hydrogenation. Furthermore, automotive lube oils typically contain about 12—14% additives. These additives maybe oxidation inhibitors to prevent formation of gum and varnish, corrosion inhibitors, or detergent dispersants, and viscosity index improvers. The United States consumption of lubricants is shown in Table 7. 

Most nonpolar substances have very small water solubilities. Petroleum, a mixture of hydrocarbons, spreads out in a thin film on the surface of a body of water rather than dissolving. The mole fraction of pentane, CsH12, in a saturated water solution is only 0.0001. These low solubilities are readily understood in terms of the structure of liquid water, which you will recall (Chapter 9) is strongly hydrogen-bonded. Dissimilar intermolecular forces between C5H12 (dispersion) and H2O (H bonds) lead to low solubility. 

This property can be used to separate highly volatile and low-viscous mineral oils from oil-water dispersions.To demonstrate this,a dispersion of 20 ml of ligroin or petroleum ether in 200 ml of water is prepared in a 400 ml beaker with a fast-running mixer.Then approx. 5 g of crushed urea/formaldehyde foam are added. After 5 min the solution is filtered through a folded filter.The aqueous filtrates are optically free from dispersed hydrocarbons. In the same way a crude oil/water dispersion can be separated. 

There are, however, important differences between resins and asphaltenes. Asphaltenes do not dissolve in petroleum but are dispersed as colloids. Resins readily dissolve in petroleum. Pure asphaltenes are solid, dry, black powders and are nonvolatile. Pure resins are heavy liquids or sticky solids and are as volatile as hydrocarbons of the same size. The resins of high molecular weight are red the lighter resins are less colored. 

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