Petroleum Waxes G.Ali Mansoori 1, H. Lindsey Barnes 2, Glenn M. Webster3 Chapter 19, Pages 525-556, 2003 Manual 37 - Fuels and Lubricants Handbook: Technology, Properties, Performance, and Testing ASTM Manual Series: MNL37WCD ___________________________________ P.O. Box C700, ASTM International, West Conshohocken, PA 19428-2959 ____________________________________ WAXES ARE USUALLY SOLID AT ROOM TEMPERATURE because they contain linear paraffinic hydrocarbons with carbon chains of various lengths. Waxes can vary in consistency from easily try as a gelling agent for organic solvents·and as a raw mate­ kneadable to brittle. They exhibit relatively low viscosity at rial used. in lipstick formulations for the cosmetic market. temperatures slightly above their melting point. The Carnauba wax is recognized generally as safe by the United ap­pearance of waxes Can vary from translucent. to opaque, States Food and Drug Administration. but they are not glassy. The consistency (i.e., hardness) and Candelilla wax is harvested from the shrubs Eurplwrbiea solu­bility of waxes depends on the temperature at which they antisiphilitica, E. cerifera, and Pedilanthuspavonis in Mexico are observed. and southwest Texas. The candelilla wax is recovered after The use of waxes dates back more than 5000 years. As early the entire mature plant is uprooted and immersed in acidi­ as 4200 B.C. the Egyptians extracted a waxy �ubstance from fied boiling water. During the immersion, the candelilla wax the honeycomb of bees and used it to satw:ite · linen floats to the surface and is skimmedoff. The primarymarket wrap­pings of mummies [!]. The spulptured porittaffof the for candelilla wax is cosmetics where it is a component in lip­ de­ceased decorating a coffin cover was often modeled stick formulations. The chemical composition of carnauba in beeswax and painted with pigmented beeswax. Another use and candelilla wax is listed in Table 2. of wax was in the preparation of erasable writing tablets. Synthetic waxes are derivedfrom either the Fischer-Trop­ Fas­tening together several tablets with fiber produced sch process [7] or by ethylene based polymerization pro­ forerun­ners. of the modern book [2]. cesses [8]. The Fischer-Tropsch (F-T) process originated in Waxes are classified by the matter from which they are de­ Germany in the 1920s and is illustratedschematically in Eq rived: insect, vegetable, synthetic, and mineral [3]. Beeswax is I. The F-T process was developed to synthesize hydrocarbons an example of insect wax. The chemical composition of and oxygenatedcompounds froma mixtureof hydrogen and beeswax is. unique and its characteristics vary with the carbonmonoxide. DuringWorld War II, the F-T process was species of the honeybee. Apis mellifera is the most common · used by Germanyto produce fuelsfrom coal-derived gas. The cultured bee in the world and will provide a chemical first commercial plant in South Africa started in 1955 at gener­alization of composition of wax for this species [ 4 ]. Sasolburg,using coal as a feedstock.The so-calledSasol pro­ Beeswax is secreted in eight glands on the underside of the cess is illustratedin Fig. I [9]. This plant produces waxes, fu­ worker bee. Bees are believed to secrete one pound of wax £Or els, pipeline gases (i.e., ethylene, methane), and other prod­ every eight pounds of honey they produce. Since secreted ucts using a fixed bed catalyst F-T process. During the F-T beeswax read­ily absorbs color, the final color of the beeswax process, carbon monoxide, which is generated from coal is influenced by the source of the pollen. A typical composition gasification, is reacted under fixed-bed conditions using ° analysis of beeswax is provided in Table I. Beeswax is high-pressure at approximately 220 C in the presence of an extracted by melt­ing or boiling the honeycomb in water and iron catalyst to produce synthetic hydrocarbon waxes, as has applications in pharmaceuticals and cosmetics, and is the shownin Eq 1. Typicalreaction products that may be derived primary com­ponent of religious candles. from the F-T process are listedin Table 3. Vegetable waxes are extracted from the leaves, bark, and berries (seeds) of plants and trees. Abnost all multi-cellular 2nH2 + nCO ->Cn H2n + nHzO (1) plants are covered by a layer of wax [5]. Only a few species Poly(ethylene) waxes may be prodticed by the industrial grown in semiarid climates produce enough wax to be com­ polymerization of ethylene using high or low pressure ethy­ mercially viable for recovery. Carnauba and candelilla wax lene polymerizationtechnology [10], or as thermal decompo­ are two of the most common vegetable waxes that are com­ sition products of the polyethylene polymers. The molecular mercially marketed [6]. Carnauba wax is removed from the weights and melting points of the synthetic waxes as com­ dried leaves (fronds) of palm trees grown in the northeast pared with the Fischer-Tropsch waxes are listed in Table 4. re­gion of Brazil. Carnauba is utilized in the polish paste The market stability of pricing and availability of insect indus- and vegetable waxes is affected by climate conditions and naturaldisasters. With the advent of the petroleumindustry, 1 University of Illinois at Chicago, Chicago, IL 60607-7052. the waxes from mineral and synthetic sources surpassedthe 2 CITGO Petr. Corp., H.W. 108 S., P.O. Box 1578, Lake Charles, LA annual production of the combined total of the other two wax 70602. categories. Waxes frominse ct and vegetable sources are mix­ 3 63 Rocklege Rd., Hartsdale, NY 10530. tures of long chain fatty acids, esters of aliphatic alcohols, and hydrocarbons. Waxes from mineral origins are chemi- 525 Petroleum Waxes G.Ali Mansoori, H. Lindsey Barnes, Glenn M. Webster Chapter 19, Pages 525-556, 2003, Manual 37 - Fuels and Lubricants Handbook: Technology, Properties, Performance, and Testing, ASTM Manual Series: MNL37WCD ____________________________________ 526 TABLE I-Compositionalanalysis of beeswax. TABLE3-Products derivedfrom the Fischer-Tropsch process. Component Amount in wt. % Approx. Typical Monoesters, C1sli.31COOC3oH61;C2s Hs1COOC30�1 55-65 Product Yield (wt.%) Diesters, triesters, hydroxydiesters 8-12 Paraffins (i.e., methane,ethane, propane, 7.2 Free fatty acids,C23COOH-C 31COOH 9.5-10.5 andbutane) Free fattyalcohols, C340H-C360H 1-2 Olefins(i.e., methylene, ethylene, propylene, 5.6 Hydroxy-monoesters,C 14H29CH(OH)COOC26H61 8-10 andbutylene) r a Hydrocabons , C2sHs2-C31H64 12-15 Gasoline (Cs-Cu) 18.0 Moistureand mineralimpurities 1-2 Diesel (C,2-C") 14.0 C19 to C23 7.0 aHydrocarbons most commonly found in beeswax include nonacosane Medium Wax (C24-C3s) 20.0 (C2�) and nentriacontane (C31H64). HardWax (>C,s) 25.0 Water soluble non-acidchemicals 3.0 Water soluble acids 0.2 TABLE 2--Chem.ical¢-, composition of camauba andcandelilla wax. Component Carnauba (wt.%) Candelilla (wt.%) TABLE 4-Comparisonof Fischer-TroJ)Schwaxes withother Monoesters 83-88% 28-30% synthetic waxes. Fattyalcohols 2-3 2-3 Free fatty acids 3-4 Type of Wax MolecularWeight Melting�oints; °C Hydrocarbonsa 1.5-3.0 7-9 Fischer-Tropschwax 500-1200 85-110 Resins 4--6 49-574--6 Low Pressurepolyethylene 900-3000 90-125 Moistureand inorganic residue 0.5-1 2-3 wax High Pressurepolyethylene 500-4000 85-130 aHydrocarbons commonly found in camauba and candelilla wax are prin­ wax cipally hentriacontane (C31l¼) and tritriacontane (C33f4s). Pyrolysisa waxes 1000-3000 90-130 aPyrolysis waxes arederive<J from thermo-crackingof polyethylene. cally inert and are primarily composed of straighfchain P0WER WATER COAL PLANT (paraffinic)hydrocarbons. STEAM Petroleum wax may vary compositionally over a wide range of molecular weight, up to hydrocarbon chain lengths AIR of approximately CS0-C60. It is typically a solid at room temperature and is derived from relatively high boiling petroleum fractions during the refining process. Petroleum waxes are a class of mineral waxes that arenaturally occur­ NH, MWCAS TARACID PIJBI1'JCAIION ring in various fractions of crude petroleum. They have a COz+lfiS wide range of applications that include: coating of drinking 1lREGAS cups; an adhesives additive; production of candlesand rub­ ber; as components of hot melts, inks, and coatings forpaper; and they can be used in asphalt, caulks, and binders. This chapter will provide a review of petroleum waxes including history,production, types, chemical composition, molecular structure, and property testing. w: 0 DISCUSSION f---+CO, C, C,IC, Classification of Crude Oils and Chemical .-------, Structure of Ingredients OILS Petroleum crude oil, commonly referred to as crude oil, is a complex mixture of hundreds of compounds including solids, liquids, and gases that are separated by the refining process. Solid. components at room temperature iriclude asphalt / bitumen and inorganics. Liquids of increasing vis­ C,, cosity vary from gasoline, kerosene, diesel oil, and light and heavy lubricating stockoils. Alsoinclud ed are themajor com­ FIG. 1-Generalized Sasol Plant for hydrocarbon synthesis . ponents of natural gas, which include methane, ethane, by the_ Fischer-Tropsch Process. propane, and butane (11). An elemental analysis of crude oil shows that it consists of primarily two elements: hydrogen (11-14%) and carbon CHAPTER 19: PETROLEUMWAXES 527 TABLE 5-Crudeoil content. Crude Type Solvent NeutralOil BaseOil Wax.Content Sulfurand Nitrogen Asphalt APIGravity" ASTM Test Method Paraffinic base Yes Yes <10% Low No >40 E-1519 Naphthenicbase No Yes No Low No <33 D-2864 Intermediatebase No Yes <6% Low Yes 33-40 D-8 Asphaltic base No Yes 0% High Yes <10 D-1079 aAmerican PetroleumInstitute gravityis an arbitraryscale expressing the densityof liquid petroleumproducts. The measuringscale is calibratedin terms of degreeAPI (0API) andcan be calculatedin termsof the formula:0 AP[= 141.5/(SGL[60°F)) - 131.5 whereSG L stands forliquid specificgravity with respect to wa­ ter. The higher the value of API gravity, the more fluidthe liquid. (83-87%). Crudeoil hydrocarbons contain long hydrocarbon TABLE6-ASTM test methods used forsampling, separation, and chains (saturated and unsaturated), branch structures, and classification of various oil samples and the proceduresused.