paraffin products developments in petroleum science

Preparative and analytical methods for studying the chemical composition of liquid paraffins and paraffin waxes a Separation methods b Chemical classification o n the basis of physical

Der&qmients in Petroleum Science, 14

Prapedcs, rech plloivggit?,~, appliuu iiot 1s

FURTHER TITLES IN THIS SERIES

FUNDAMENTALS OF NUMERICAL RESERVOIR SIMULATION

7 G.V CHILINGARIAN and T.F YEN (Editors)

BITUMENS, ASPHALTS AND TAR SANDS

8 L.P DAKE

FUNDAMENTALS OF RESERVOIR ENGINEERING

9 K MAGARA

COMPACTION AND FLUID MIGRATION

10 M.T SILVIA and E.A ROBINSON

DECONVOLUTION OF GEOPHYSICAL TIME SERIES IN THE EXPLORATION FOR OIL AND NATURAL GAS

11 G.V CHILINGARIAN and P VORABUTR

DRILLING AND DRILLING FLUIDS

12 T VAN GOLF-RACHT

FRACTURED HYDROCARBON-RESERVOIR ENGINEERING

13 F JOHN FAYERS (Editor)

ENHANCED OIL RECOVERY

Developments in Petroleum Science, 14

ELSEVIER SCIENTIFIC PUBLISHING COMPANY

AMSTERDAM -OXFORD - NEW YORK 1982

Joint edition published by

Elsevier Scientific Publishing Company, Amsterdam, The Netherlands and

Akadkmiai Kiadb, The Publishing House of the Hungarian Academy of Sciences, Budapest, Hungary

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Library of Congress Cataloging in Publication Data

K6olaj p a r p n o k English

Paraffin products

(Developments in petroleum science; 14)

Translation of: Ki3olaj paraffinok

CONTENTS

I CHEMICAL, CRYSTALLOGRAPHICAL AND PHYSICAL PROPERTIES OF

(A) Liquid paraffins and paraffin waxes from petroleum

1 Composition of petroleum distillation products

2 Nomenclature of liquid paraffins and paraffin waxes

Literature

(B) Chemical properties of liquid paraffins and paraffin waxes

1 Preparative and analytical methods for studying the chemical composition of liquid paraffins and paraffin waxes

(a) Separation methods

(b) Chemical classification o n the basis of physical characteristics

(c) Analytical methods for the determination of individual hydrocarbons or

of compositions of their mixtures

2 Chemical composition of liquid paraffins and paraffin waxes

3 Chemical properties of individual alkanes and their mixtures

(a) The reactions of paraffins with halogens

(b) Sulfochlorination of alkanes

(c) Reactions of liquid paraffins and paraffin waxes with sulfur dioxide, sulfur

(d) Reaction of liquid paraffins and paraffin waxes with nitric acid

(e) Oxidation of liquid paraffins and paraffin waxes

( f ) Thermal decomposition and isomerization of alkanes

trioxide, sulfuric acid and fuming sulfuric acid (oleum)

Literature

(C) Crystal structure of paraffin waxes

1 Crystal structure and crystallization

2 Crystal structure and habit of individual alkanes and their mixtures

Literature

(D) Physical properties of paraffin waxes

1 Melting point, boiling point and melt viscosity

2 Density and thermal expansion

(C) Dewaxing processes using solvents

1 Methyl ethyl ketone dewaxing

2 The propane dewaxing process

3 Dewaxing with a mixture of propylene and acetone

4 Dewaxing with chlorinated hydrocarbons

5 Dilchill dewaxing process

6 Filter aids

Literature

(D) De-oiling and fractional crystallization of slack waxes and petrolatum

Literature

(E) Manufacture of n-alkanes

1 n-Alkane manufacture based on adduct formation with urea

(a) Mechanism of adduct formation, factors affecting adduct formation,

(b) Technology of adduct formation

(a) Composition, structure and adsorption properties of synthetic molecu-

(b) Manufacture of n-alkanes using molecular sieve processes

CONTENTS

III APPLICATIONS OF PARAFFIN WAXES AND LIQUID PARAFFINS

(A) Direct applications of paraffin waxes and liquid paraffins

Literature

1 Paraffin waxes in the paper industry

(a) Paraf6n waxes for impregnation

(b) Paraffin waxes in coatings

(c) Paraffin waxes for lamination

(13) Paraffin waxes as additives to paper sizes

Literature

2 Application of paraffin waxes in household chemicals (by Gy Buktuy)

(a) Polishes with paraffin wax as an additive

(b) Candles

Literature

3 Application of paraffin waxes in the cosmetics industry (by Gy Baktay)

(a) Solid perfumes

(b) Cosmetic creams

(c) Beauty masks

(d) Protective creams for industrial workers

(e) Facial care and beauty products

(f) Hair preparations

(g) Anti-perspirants

Literature

Literature

4 Application of paraffin waxes in the food industry and in agriculture

5 Other fields of application for paraffin waxes

(a) The match industry

(b) The rubber industry

(c) Precision casting

(d) The manufacture of refractory ceramics

(e) The electrical industry

( f ) Paraffin wax emulsions in building construction

216

211

(c) Factors affecting the manufacture and grade of chlorinated paraffins 280

1 Manufacture and utilization of chlorinated paraffins

(b) Batchwise and continuous chlorination of paraffins

of paraffins, and utilization of the products

(a) The main variants of paraffin oxidation

8 CONTENTS

(b) The manufacture of fatty acids by paraffin oxidation 290

(c) Manufacture of alcohols by paraffin oxidation 298

(d) Utilization of paraffin oxidation products 302

4 Manufacture of olefins, liquid a t ambient temperature, from paraffins, and

(a) Manufacture of olefins from paraffin waxes and paraffin crudes 305

(b) Applications of high molecular weight alpha-olefins 315

( C ) The manufacture of proteins and organic acids from hydrocarbons by biosyn-

(a) Significance of the problem and present situation 323

(b) Manufacture of single cell protein (petroleum yeast) 325

(c) Properties and use of single cell protein 327

PREFACE

On a world-wide basis, the share of petroleum waxes related to the total o petroleum products is tiny In 1975, for example, only 1.5 million tons of paraffin waxes were produced from a total output of 2,700 million tons of crude oil, thus amounting to only 0.06% Even if lower molecular weight paraffin products are included, the share - as compared to other petroleum products - remains insignificant

When, however, the greatly varied direct applications of solid and liquid par- affins in industry, and their utilization as raw materials in the petrochemical in- dustry are considered, their importance becomes immediately obvious For this reason it appeared of interest to summarize - without claiming completeness - the basic facts and data on the manufacture, applications, physico-chemical and chemical properties of these products in a monograph suited to both research and

to industrial audiences Nomenclature is also discussed

The authors hope that the present book will be of assistance to all who wish to obtain an overall coherent view of paraffin waxes and related products, their prop- erties, manufacture and applications

This English edition is a revised version of the Hungarian original It includes the most recent information available to the authors on the topics covered

I

The Authors

This Page Intentionally Left Blank

INTRODUCTION

Paraffinic hydrocarbons, or paraffins are straight-chain or branched saturated

organic compounds with the composition C,,H2,,+2 The term paraffin waxes is

used for mixtures of various hydrocarbon groups, especially paraffins and cyclo- alkanes, that are solid at ambient temperature

Paraffins are present in large amounts in nature, but can also be produced syn- thetically and are formed as by-products in processing certain natural substances Paraffins of low molecular weight are found in natural gas, paraffins of medium and high molecular weight in petroleum and ozokerite On industrial scale, par- affins can be manufactured from coal by the well-known Fischer-Tropsch syn- thesis Paraffins are also obtained from the tar-like products obtained by the dry distillation of coal (mainly brown coal) and other organic materials (wood, lig- nite, bituminous shales, fish tallow etc.)

In view of present trends, this book will deal with the Structure, properties, manufacture and application only of paraffins obtained from petroleum, and that are liquid or solid at ambient temperatures Among liquid paraffins, only mixtures

containing higher than Clo alkanes, cycloalkanes and, in smaller amounts, aro-

matic hydrocarbons will be discussed in detail Alkanes that are gaseous at am- bient temperature will not be considered in this book

Paraffins, liquid at ambient temperatures and containing higher than Clq al- kanes are produced from the kerosine and gas oil fractions obtained by the distilla- tion of hydrocarbon crudes at atmospheric pressure Paraffin waxes, solid at ambient temperature, are obtained from lubricating oil fractions having various average boiling-points, from distillation residues resulting from the vacuum distillation of hydrocarbon crudes, and from the so-called tank waxes and pipeline waxes sep- arated during the storage and transport of such crudes

In the following, the terms liquid paraffins and solid paraffin waxes will always

be used in the above sense Whenever individual members of the homologous series of paraffins are in question, they will be termed alkanes to avoid confusion

Liquid paraffins from petroleum consist of ClO-Cl8, mainly normal hydrocar-

bons that are liquid at ambient temperature The average molecular weight varies from 150 to 250

The nomenclature of paraffin waxes with different crystal structures will be discussed in detail in the following However, we wish to mention in advance that

crocrystals and the major part of these waxes consists of C,o-C,, compounds The

melting point of microcrystalline paraffin waxes varies between 60 and 90 "C The world production of paraffin wax increases from year to year However, whereas this increase was around 60% between 1950 and 1960, the growth rate has decreased since 1960 This is mainly due to plastics (polyethylene, PVC,

polystyrene, cellophane etc.) being increasingly used in packaging

It is of interest to note that while around 90% of the world production of par- affin wax in 1960-1961 consisted of macrocrystalline paraffin wax, the present growth rate of microcrystalline paraffin wax production is substantially higher than that of macrocrystalline paraffin wax Sherwood's data indicate that appli- cation of microcrystalline paraffin wax in the U.S.A increased by 170% as early as

in the period 1948-1958, whereas for macrocrystalline wax the increase over the same period was only 10% This shift is the result of the already mentioned ex- pansion in the use of plastics in packaging This same reason urged paraffin wax producers to improve the properties of both macro- and microcrystalline paraffin waxes by means of additives A rich choice of such products is now available on the world market

I CHEMICAL, CRYSTALLOGRAPHICAL

AND PHYSICAL PROPERTIES OF LIQUID PARAFFINS

AND PARAFFIN WAXES

(A) Liquid paraffins and paraffin waxes from petroleum

1 Composition of petroleum distillation products

/

Crude oils and their products contain a large number of individual paraffins The main physical characteristics of the most frequently occurring alkanes are

listed in Table 1-1, indicating that n-pentane is already liquid and n-hexadecane

solid at ambient temperature

Table I-I Physical characteristics of some alkanes occurring in petroleum

- 138.5

- 159.5 C,Hn 72

- 129.5

- 159.5

- 16.5 GHi, 86

- 94.0

- 153.5 -118.0

28.0

9.5

69.0 60.0 63.0

49.5

58.0

98.5 19-93

0.424' 0.546' 0.582'

0.602' 0.596'

0.625

0.620

0.6139

0.659 0.656 0.664

0.649

0.662

0.684 :.%)

14 I PROPERTIES OF LIQUID PARAFFINS AND PARAFFIN WAXES

Table I-1 (cont.)

Compound

Formula ~ $: I point, "C I point, "C at 2ooc I oc I press,,

(101 kPa) (101 kPa) MPa

- 107.5 between

and + 1 0 4 6

128 -53.3

-

142 -29.5

3044

3314

4214

0.740 0.749 0.763 0.174 0.782 0.789 0.801 0.810 0.7813 0.7943

and cycloalkane content of gasoline products over the 40-120 "C distillation

range, obtained from different crudes

With increasing average molecular weight, the composition of petroleum frac- tions is more and more complex The alkane, cycloalkane and aromatics content

of different gasoline and naphtha fractions obtained from three different crudes

(A) LIQUID PARAFFINS AND PARAFTIN WAXES FROM PETROLEUM 15

AI- ~ Cyclo- I Aro- 1 Al- I Cyclo- 1 Aro- I * Al- 1 Cyclo- 1 Aro-

Vol- %

Sources

n-Alkanes 1 iso-Alkanes 1 Cyclopentanes I Cyclohexanea

Greendale-Kawkalin field,

is shown in Table 1-3 It can be noticed that in the case of the fractions from the Yates field the alkane content decreases, while the cycloalkane content substan- tially increases with the boiling range In the case of the other two crudes no such unequivocal change could be observed with regard to alkanes and cycloalkanes, while their aromatics content was the highest in the 95-1 15 "C fraction Table 1-4 lists the hydrocarbon composition of the kerosine and light gas oil fractions of

Table Z-3 Alkanes, cycloalkanes and aromatics content of petroleum fractions

from different sources

Table 1-4 Hydrocarbon composition of kerosine and gas oil fractions

of petroleum from the Ponca field

Boiling point range (101 kPa) 180-23OoC I 230-300°C

16 I PROPERTIES OF LIQUID PARAFFINS AND PARAFFIN WAXES

Viscosity index

crude from the Ponca field It can be observed that the content in bicycloalkanes and bicyclic aromatics increases with the boiling point

The fractions and the distillation residues suitable for the manufacture of lu- bricating oils have a still more complex composition In these distillation fractions the carbon atom number of the components varies between 25 and 40 In the re- sidual oil compounds with 50 to 60, and in some cases up to 80 carbon atoms are found The chemical composition of the lubricating oils obtained by refining these materials differs from the composition of the starting distillates and residual oils actually as a result of the refining operations This theme, however, is outside the scope of this book The different compositions, depending on their average molecular weight (viscosity) and extent of refining (viscosity index) are shown in

Table 1-5, presenting the carbon atom distribution determined by the so-called

Carbon atom distribution, %

aromatic 1 cycloalkane 1 alkane

Table Z-5 Carbon atom distribution among aromatic, cycloalkane and alkane

compounds in refined lubricating oils

Oil type

High viscosity index aircraft oil

High viscosity index motor oil

Medium viscosity index motor oil

Low viscosity index oil

* S.S.U.: flow time in seconds, measured with a Saybolt Universal viscorneter

n-d-M method, that is, the distribution of the total number of carbon atoms con- tained in the compounds constituting the lubricating oil between the individual groups of hydrocarbons

The highly complex composition of high boiling-point fractions is represented

by the data in Table 1-6 referring to a lubricating oil fraction composed of C25-C35

Table 1-6 Composition of a CzsC,, lubricating oil fraction

Tri- and polycycloalkanes

Monocyclic aromatics with cycloalkane rings

Bicyclic aromatics with cycloalkane rings

Tricyclic aromatics with cycloalkane rings

Polycyclic aromatics with low hydrogen content and

non-hydrocarbon compounds

13.7

8.3 18.4 9.9

16.5 10.5

8.1

6.6

8.0

(A) LIQUID PARAFFINS AND PARAFFIN WAXES FROM PFTROLEUM 17

compounds, obtained by fractional distillation from the Ponca field crude A com- parison with the data of Table 1-4 unequivocally confirms that the higher-boiling fractions contain much more cycloalkanes and aromatics than the lower-boiling fractions

From this short summary of the composition of crude petroleums it may be seen that paraffin waxes produced mainly from higher-boiling distillates and re- sidual oils contain normal hydrocarbons as well as large amounts of iso-alkanes Also, significant amounts of one, or more ring hydrocarbons with straight side chains can be found

2 Nomenclature of liquid parafis and paraffin waxes

All classifications regarding a range of products are more or less arbitrary, or valid only with certain restrictions

It is, however, a basic postulate, when establishing some nomenclature system, that in addition to an endeavour at simplicity, both the technological and applica- tion aspects of the products in question should assert themselves

The manufacture of liquid paraffins and paraffin waxes will be discussed in Chapter 11, their application in Chapter 111 In conformity with these chapters

we established a nomenclature system, which, in our opinion, satisfies the above basic requirements This nomenclature will be applied in the course of this book Widely varying terms are used in the literature, in the technological practice of the petroleum industry and in commerce for different grades of liquid paraffin and paraffin waxes

The terms slab paraffin wax, slack wax, scale wax, and pipeline or tank wax were established in earlier petroleum industrial practice The term slab wax was used exclusively for paraffin waxes obtained by cooling, pressing and sweating from low-viscosity distillates Only pressing and sweating were feasible for the separation of the oily part and the solidified paraffin wax, since centrifuging could not be applied The term slack wax, or slacks, was used for the intermediate product of cooling and pressing without sweating or refining, and the product produced by sweating was called scale wax On the other hand, petrolatums from residual oils and pipeline or tank waxes cannot be pressed, but only centrifuged

in solvent media This was an important aspect at the time when dewaxing by means of solvents was not yet known The fraction distilling over between those that could be dewaxed by pressing and sweating and those that could be dewaxed

by centrifuging was called the intermediate fraction This intermediate, that is,

paraffinic medium and heavy distillate, could be dewaxed only under great dif€i- culties and with very poor yields either by pressing or by centrifuging The paraffin waxes obtained from the intermediate fraction were called slop wax The inter- mediate fraction was often used as fuel without recovering its paraffin wax content

At present, when solvent dewaxing processes have completely conquered the field, these aspects, and the terms connected with them, will obviously lose their importance

2

18 I PROPERTIES OF LIQUID PARAFFINS AND PARAFFIN WAXES

Classification of paraffin waxes :

Paraffin waxes with macrocrystalline structure can be classified e.g with respect

to their melting point or to the extent of refining On the basis of the melting p o b t

one can distinguish between soft paraffin waxes with melting points below 45 "C,

and hard paraffin waxes with melting points between 45 and 60°C and needle penetration values below 20 mm/lO at 25 "C Depending on the degree of refining, one can classify paraffin waxes as technical, semi-refined and refined grade waxes

Technical grade paraffin waxes usually contain less than 6 wt-% oil; these are

products obtained by dewaxing from slacks Semi-refined paraffin waxes may con-

tain a maximum of 3 wt- % oil, and their colour is light yellow to white Finally, refined paraffin waxes contain 0.4 to 0.8 wt- % oil, they are completely colourless, odourless and do not contain substances detrimental to health

Our nomenclature system is based on the classification of paraffin waxes into macrocrystalline and microcrystalline groups

The crystal structure of macrocrystalline (slab) paraffin waxes can be observed visually, while that of microcrystalline paraffin waxes only with a microscope The term amorphous is thus sometimes found in the literature for paraffin waxes

obtained from residual oil As it is known all paraffin waxes obtained from petro-

leum are crystalline below their setting point The size of the crystals, however, decreases with the increasing boiling point of the paraffin wax

Microcrystalline para& waxes have higher molecular weights, densities and refractive indices than macrocrystalline paraffin waxes From the view of both processing and application, it is an important property of microcrystalline para& waxes that they are capable of retaining more oil than macrocrystalline waxes The structural difference is also confirmed by the observation that blending macro- crystalline slab wax with only a few tenths of a per cent of microcrystalline par- affin wax changes the ease of pressing and sweating the former

After these preliminary remarks, our classification system is shown in Fig 1-1

The raw materials for liquid paraffins are the distillates obtained by the distilla- tion of petroleum crudes The raw materials for paraffin waxes are the light, inter- mediate and heavy hydrocarbon oil distillates obtained by the vacuum distillation

of the latter, the residual oils of vacuum distillation, and pipeline and tank waxes The semiproducts obtained in the first stage from light, intermediate and heavy distillates, from residual oils and from pipeline and tank waxes cannot yet be re- garded as paraffin waxes They are termed slacks and petrolatums, respectively The difference between paraffin waxes and slacks and petrolatums is in their oil content, and hence in their chemical composition The differences in chemical composition are obviously affected by the conditions of de-oiling

Macrocrystalline paraffin wax is produced from the slacks obtained from paraf- fin light oil distillates Microcrystalline paraffin waxes, both of the brittle and the ductile type, are obtained from petrolatum Ductile microcrystalline paraffin waxes include two sub-groups, namely plastic and elastic paraffin waxes Another term used for the low oil-content macrocrystalline paraffin waxes is slab paraffin waxes The term ceresin is reserved exclusively for brittle microcrystalline paraffin waxes

(atmospheric

Paraffin light distillates distillation)

paraffins

Slack wax

0

I Macrocr ystalline

Plastic micro- crystalline paraffin waxes

&

L

Fig I-I Sources and classification of liquid paraffins and paraffin waxes from petroleum

20 I PROPERTIES OF LIQUID PARAFFINS AND PARAFFIN WAXES

The products obtained from slacks and petrolatums, named according to our nomenclature, are products not subjected to further purification Whatever method

is used for further purification, it will not change, or only change insignificantly, apart from colour, odour and content in bi- and tricyclic aromatics, the charac- teristics of these products The products that have undergone further purification are distinguished by the attribute "purified"

The differences between the characteristics of macrocrystalline, intermediate and microcrystalline paraffin waxes not subjected to purification, and their classi- fication based on these differences is shown in Table 1-7 The basis of our classi-

fication is the melting point, kinematic viscosity at 100 "C, penetration at 25 "C,

breaking point (Fraass) and oil content (ASTM) In our view, the totality of these characteristics is necessary and sufficient for an unequivocal characterization of the paraffin wax in question, its structure, oil content and mechanical character- istics

Table I-7 Classification of macrocrystalline, intermediate and microcrystalline

paraffin waxes by their characteristics

Breaking point (Fraass), O C >+25

Oil content (ASTM), wt-% <0.8

Viscosity at 100 OC, mm*/s

ductile Interme-

Asinger, F., Paraffins, Chemistry and Technology Pergamon Press, Oxford (1968)

Finck, E., Fette, Seifen, Anstr-Mittel, 62, 502 (1960)

Forziati-Willingham-Mair-Rossini: J Res natn Bur Stund., 82, 11 (1944)

Gruse-Stevens: Chemical Technology of Petroleum MacGraw Hill, New York (1960)

Hoffmann, H J., Erdol, Kohle, 17, 717 (1964)

Ivanovszky, L., Chem Tech Berf., 11, 315 (1959)

Kreuder, W., Seifkn-ale-Fette- Wachse, 84, 665, 699, 735, 773, 849 (1958)

- : Seifen-ale-Fette-Wachse, 85, 19, 41, 67, 93 (1959)

Mair-Rossini: Ind Engng Chem., 47, 1062 (1955)

Marx-Presting: Chem Tech Berl., 7, 662 (1955)

Mazee, W M., Modern Petroleum Technology, 3rd ed (Ed E B Evans), Institute of Petro-

Perry, J H., Chemical Engineers' Handbook McGraw-Hill, New York (1950)

Phillips, J., Petrol Refiner, 38, 193 (1959)

Rossini-Mair: Adv Chem Ser., No 5, 334 (1951)

leum, London (1962)

(B) CHEMICAL PROPERTIES OF LIQUID PARAFFINS AND PARAFFIN WAXES 2 1 Rumberger, J., Symposium on Composition of Petroleum Oils, Determination and Evaluation

Teubel-Schneider-Schmiedel : Erddlparajine VEB Deutscher Verlag fur Grundstoffindustrie,

Tuttle, J B., Petroleum Products Handbook (Ed V B Guthrie), McGraw-Hill, New York

Wolff, G., Coating, 9, No 1 13 (1976)

ASTM, p 283 (1958)

Leipzig (1965)

(1960)

(B) Chemical properties of liquid paraffins and paraffin waxes

The chemical properties of liquid paraffins and paraffin waxes obtained from

- preparative and analytical methods for studying the chemical composition

- determining the chemical composition of the paraffins,

- determining the chemical properties of individual paraffin hydrocarbons

petroleum are in relation with the following steps :

of liquid paraffins and paraffin waxes,

1 Preparative and analytical methods for studying the chemical composition

of liquid paraffins and parailin waxes

The determination of the chemical composition of liquid paraffins and paraffin waxes can only be carried out after cumbersome separation procedures and sub- sequent analyses including spectral analysis, gas chromatography, etc In the case

of paraffin waxes with higher average molecular weight it is almost impossible, even using the most laborious operations, to achieve complete separation of individual compounds In general, the objective is to produce narrow fractions whose components are closely similar or identical with regard to chemical structure

An approach to the chemical nature of a given paraffin wax is also yielded by phys-

ical characteristics, whose values are closely related, for a given molecular weight,

to the structure of the molecule

For determining and characterizing the chemical composition of paraffin waxes, essentially three groups of preparative and analytical procedures are available:

- separation methods,

- classification methods based on physical characteristics,

- analytical methods for the determination of individual components

2 2 I PROPERTIES OF LIQUID PARAFFINS AND PARAFFIN WAXES

- fractional crystallization,

- adduct formation with urea and column chromatography on urea,

- separation using molecular sieves,

- elution chromatography,

- thin layer chromatography

Separation by distillation is based on the differing boiling points of the compo- nents This separation method is much limited, since the boiling points of the successive members of the n-alkane series, particularly in the case of compounds containing more than 25 C-atoms, are very close to one another Therefore; pre- parative separation by distillation is effective mainly in the case of < C , n-al- kanes This separation method is difficult to apply to iso-alkanes and cycloalkanes, since the boiling points of the members of these two homologous series overlap

If a mixture of pure n-alkanes has been ffrst separated, by some method, from the material to be analyzed, the distribution of the compounds in the mixture can

be determined by molecular distillation

It is obvious from what has been said that separation by distillation is much less effective in the case of microcrystalline paraffin waxes than in the case of liquid paraffins and macrocrystalline paraffin waxes

A successful method for the separation of microcrystalline paraffin waxes is

fractional crystallization based on differential solubility Ketones, mixtures of ketones and aromatics, halogenated hydrocarbons and different gasoline grades have been used as solvents in research up to the present Fractional crystallization yields fractions of both macrocrystalline and microcrystalline paraffin waxes differ- ing in molecular structure and molecular dimension At higher temperatures of crystallization, fractions containing higher molecular weight and less branched alkanes, as well as cycloalkanes with long side chains will crystallize With suc- cessive lowering of the temperature, the fractions will contain more and more iso-alkanes and cycloalkanes with shorter side chains; simultaneously the average molecular weight of the fractions will decrease

n-Alkanes can also be separated from iso- and cycloalkanes by urea adduct formation X-ray studies have shown that the long chains of n-alkanes as well

as long chains, if present, of iso- and cycloalkanes are enclosed in the tubular channels of the adduct, and this results in a hexagonal urea lattice Urea crystal- lizes in the hexagonal system only when an adduct is formed, its normal crystal system being tetragonal Straight-chain derivatives of n-alkanes, e.g carboxylic acids, alcohols, esters, amines etc are also capable of adduct formation

Adduct formation between n-alkanes and urea takes place in solutions of the former in gasoline, benzene or halogenated hydrocarbons when solid urea or an aqueous or alcoholic urea solution is added When solid urea is applied, a small amount of a wetting agent, i.e water, alcohol or some other substance with a s h i - lar effect is necessary Adduct formation is inhibited by resins, bituminous sub- stances, sulfur compounds, etc It is, therefore, important to remove such sub- stances from the material before adduct formation, by elution chromatography

or some other method

(B) CHEMICAL PROPERTIES OF LIQUID PARAFFINS AND PARAFFIN WAXES 23

Adduct formation is an equilibrium reaction, the equilibrium being dependent

on temperature, concentration of urea and adduct-forming components, and nature of the solvent Adduct formation is exothermic, the heat of reaction is the higher, the longer the alkane chain Hence the stability of the adduct is the greater the longer the adduct-forming molecule chain Short-chain n-alkanes form adducts only at low temperatures, and these products will readily decompose The following method was used by Hessler and Meinhart Dilute solutions of macro- and microcrystalline paraffin waxes in carbon tetrachloride were prepared, methyl alcohol saturated with urea was added and the mixture vigorously agitated The crystalline precipitate formed was filtered, washed with alcohol and dried

The decomposition of the adduct was carried out with distilled water at 70 "C

A diagram of the urea adduct method developed in the Hungarian Oil and Gas Research Institute is shown in Fig 1-2

As well as urea, thiourea can also successfully be used for studying the chemical composition of complex mixtures of hydrocarbons and their derivatives Thiourea forms adducts most readily with branched compounds

The essence of columnchromatography, using urea, is as follows The substance

to be studied is introduced, in the form of a solution, into a column filled with urea Those components of the substance which, under the given conditions, namely thermostatted temperature, presence of activator in the column and per- colation time, form an adduct with urea will be bound, 'while the unreacting components will remain in solution and will be eluted from the column by washing with solvent, and determined quantitatively Subsequently, those components having formed adducts will be eluted by successive stepwise increases of the tem- perature The temperatures corresponding to these steps will determine the struc- ture and average molecular weight of the eluate fractions

Molecular sieves are zeolites consisting of aluminium, calcium, alkali and hydro- gen orthosilicates Their characteristic feature is the ready compensation of the negative charges of their tetrahedral and A10i5 crygtal lattices by cation exchange The interconnected voids in their lattices contain combined water that can reversibly be removed by heating Dehydrated zeolite is capable of binding molecules having suitable dimensions to fit into the voids

For the separation of n-alkanes from hydrocarbon mixtures, synthetic molecular sieves of the so-called 5 '8, type are suitable The average diameter of their pores

is 5 A, their chemical composition is Me,,/n[(A1OJl, * (Si02)lz] - 27 H,O

For chemical group analysis of liquid paraffins and macro- and microcrystalline paraffin waxes, column chromatographic separation methods based on the work

of Mair, Rossini, Spengler, Snyder and Heinze are well suited Silica gel or acti- vated alumina is preferably used as adsorbent The ratio of adsorbent to sample

is between 20 : 1 and 30 : 1 The sample is introduced in the form of a dilute solution in gasoline or hexane The succession of the eluents is that of the increas-

ing polarity, e.g hexane, mixture of hexane and benzene, benzene, methanol and chloroform This method allows separation of saturated hydrocarbons, and mono-, bi- and tricyclic aromatics with satisfactory sharpness

24 I PROPERTIES OF LIQUID PARAFFINS AND PARAFFIN WAXES

.

Adduct formation (25"C, 96 h)

Solution of ;so-alkanes Aqueous t

in benzene solution of urea Washed adduct

Distilled Removal of solvent

Aqueous solution of urea Is0 - alkanes

n-Alkanes +solvent

Removal of solvent

n -Alkanes

Fig 1-2 Method for determining the n-alkane and iso-alkane content in macrocrystalline

and microcrystalline paraffin waxes

(B) CHEMICAL PROPERTIES OF LIQUID PARAFFINS AND PARAFFIN WAXES 25

Iso-alkanes

I Slack wax ]

A l k y l - substituted aromat tcs

A

Separation' of olefins with mercury acetate

i

Olefin - free slack wax

I aromatics, resins Column chromatogr.aphy 1

on silica gel

Column chrdmatographtj

a1 k y I - substituted aromat ics

Fig 1-3 Combined separation method of Spengler and Jantzen

n-alkanes

A more detailed chemical study of macro- or microcrystalline paraffin wax requires a combination of separation methods A diagram of a combined separa- tion method developed by Spengler and Jantzen is shown in Fig 1-3

Separation of macro- and microcrystalline paraffin waxes by thin-layer chromatog- raphy was developed, among others, by Dietsche and Sucker They used a 250

26 I PROPERTIES OF LIQUID PARAFFINS AND PARAFFIN WAXES

Gm silica gel support layer impregnated with 40 % urea To avoid recrystallization

of the urea, a small amount of sorbite was applied The paraffin wax to be studied was applied in a 1 % solution in benzene, at 50 to 60 "C The solvent used for

runs was a mixture of carbon tetrachloride and ethanol saturated with urea

By using a suitable solvent composition and temperature (around 50 "C), they

succeeded in obtaining satisfactory separation of the paraffin wax with respect

to chain length and degree of branching By using appropriate conditions and simultaneous runs with reference standard materials, they could determine the ratio of n- and iso-alkanes in macrocrystalline paraffin waxes

( b ) Chemical classijcation on the basis of physical characteristics

According to Etessam and Sawyer, the relationship between the melting poirlt and the molecular weight for n-alkanes is

where d: is the density a t 90 "C relative to that of water a t 4 "C

From these equations the so-called ring value is derived, since

lo3 * d y = 716 f 0.75 m.p (1-2)

M

M + 95

and the ring value, indicating the density increases due to ring closure as compared

to the equimolecular n-alkane, is

(1-4)

The so-called asymmetry value is obtained from the Etessam and Sawyer

relationship by introducing a factor of 0.75:

reach 5, while for cycloalkanes the ring value can be as high as 100 In the simulta-

neous presence of iso-alkanes and cycloalkanes, the ring value will have inter-

(B) CHEMICAL PROPERTIES OF LiQUID PARAFFINS AND PARAFFIN WAXES 27

mediate values, depending on the number and nature of branchings To decide for mixed paraffin waxes whether they are composed mainly of iso-alkanes or cycloalkanes, it is necessary to know both the ring value and the asymmetry value

In such cases the so-called sum value (s.v.) yields the answer, its value for n-alkanes being zero:

S.V = r.v + a.v = lo3 * d: - 716 - 0.75 m.p (1-6)

According to Spengler and Jantzen the relationship between refractive index and melting point permits calculations on the iso-alkane, cycloalkane and alkyl- substituted aromatics content in paraffin waxes For n-alkanes, this relationship has the form:

where n: is the refractive index a t 70 "C

Similar relationships are valid for iso- and cycloalkanes and alkyl-substituted aromatics However, the straight lines representing the latter rekdtionships inter- sect the substantially steeper straight line for n-alkanes The point of intersection

is not known exactly, but is around the melting point values of 125 to 130°C

and nD = 1.4580 Such a refractive index versus melting point diagram is shown

in Fig 1-4 If the measured values of some paraffin wax or of one of its fractions

are placed into this diagram, certain conclusions can be made regarding its composition

28 I PROPERTIES OF LIQUID PARAFFINS AND PARAFFIN WAXES

Hersch and Fenske found that the naphthenic ring content of aromatics-free

paraffin waxes or their fractions can be determined using the Watterman n-d-M

ring analysis modified by them Their methods are as follows:

- the average number of naphthenic rings per molecule is

RN = 0.284 [(n: - 1.4750)M + 8.79]0*8' ;

CN = 2.08 [(n: - 1.4750)M + 8.79]0*73 ;

(1-8)

(1-9)

- the number of carbon atoms combined in naphthenic rings is

- the percentage of naphthenic rings is

N = - 2890 [(n: - 1.4750)M + 8.79]0-73,

where n z is the refractive index at 20 "C

( c ) Analytical methods for the determination of individual hydrocarbons

or of compositions of their mixtures

The methods discussed in the previous paragraphs are suitable to give an overall approach to the chemical composition of macro- and microcrystalline paraffin waxes This is satisfactory in many cases for manufacturing and application pur- poses If, however, individual hydrocarbons must be determined, gas chromatog- raphy, mass spectrometry and infrared spectrometry method have to be used High-temperature gas chromatography and mass spectrometry methods suit- able for the analysis of paraffin waxes have been frequently discussed in the recent literature

For the gas chromatography of macrocrystalline paraffin waxes, temperatures between 250 and 350 "C are used The paraffin wax is retained by stationary liquid phase and individual components are stripped from the column, according to their volatility, using hydrogen or helium as carrier gas The fractions eluted are recorded with thermal conductivity or flame ionization detectors Different selective liquid stationary phases are in use, e.g silicone oils, distillation methyl silicone fluid, carborane (methyl silicone fluid) etc Gas chromatographic analysis

of paraffin waxes will not be discussed in detail here It will only be mentioned that apparatus and techniques exist that allow the determination of individual hydrocarbons up to CS5

The results of Levy and co-workers are particularly worth mentioning They combined high-temperature gas chromatography and mass spectrometry methods, and achieved qualitative and quantitative determination of 67 individual compo- nents in a refined macrocrystalline paraffin wax It is, in general, effective to use

a suitable form of gas chromatography for separation, and mass spectrometry for subsequent identification

(B) CHEMICAL PROPERTIES OF LIQUID PARAFFINS AND PARAFFIN WAXES 29

There are many reports on infrared spectrometric studies of paraffin waxes However, no generally accepted analytical method has yet been established for the determination of other than normal hydrocarbons In the IR spectrometry

of paraffin waxes, absorption bands are, in general, within the 600 to 3530 cm-' range Such analyses were successful in differentiating and detecting primary, secondary and tertiary carbon atoms The presence of iso-alkanes and cycloal- kanes in paraffin waxes forming urea adducts could qualitatively be confirmed Using IR spectroscopy, some authors succeeded in determining the extent of branching, whilst others determined the numbers of methyl and methylene groups

In addition to these instrumental analytical methods, various chemical analytical procedures were developed for identifying or determining a given group of com- pounds The antimony pentachloride method shall be mentioned as an example This is based on the finding that n-alkanes, in carbon tetrachloride solution, do not react with antimony pentachloride, whereas iso-alkanes form an insoluble, pitch-like substance Thus, the n-alkane content in macro- and microcrystalline paraffin waxes can be determined

2 Chemical composition of liquid paraffins and parnffin waxes

Liquid paraffins have a relatively simple chemical composition, as they consist almost entirely of n-alkanes The products manufactured by different companies for different purposes show only slight variations in the molecular weight range

On the other hand, the chemical composition of macrocrystalline and micro- crystalline paraffin waxes varies over an almost infinite range of combinations, varying according to the source of the crude petroleum and to processing tech- nology

To characterize the chemical composition of paraffin waxes, let us first sum- marize the general ideas, and subsequently present the composition of some paraffin waxes from different sources

As demonstrated by spectroscopic studies, paraffin waxes consist mainly of saturated hydrocarbons The number of aromatic ring compounds, particularly

in the case of macrocrystalline paraffin waxes consisting of compounds of lower molecular weight, is so small that they have practically no effect on the prop- erties of the waxes In fact, the majority of these rings are present as alkylbenzene derivatives and in condensed forms, and hence detrimental to health

In studying the composition of liquid paraffins let us consider the work of Mikhaylov and co-workers who studied the composition of a liquid paraffin obtained by urea dewaxing of a Diesel fuel from a high sulfur-content crude, and subsequent refining by adsorption This liquid paraffin contained 0.2 wt- %

aromatics, the amount of hydrocarbons forming no adducts with urea was relatively small Table 1-8 lists the most important properties of the liquid paraffin, and the products obtained by twice repeated treatment with urea As may be seen, the fractions forming no adducts with urea become enriched in iso-, cyclo-

30 I PROPERTIES OF LIQUID PARAFFINS AND PARAFFIN WAXES

I

1

Table 1-8 Chemical composition and physical properties of liquid paraffin,

of its urea-adduct forming parts and parts forming no adduct with urea

n-al- 1 phenyl- 1 iso-alkanes ~~~~i~~ Refr index Melting

(B) CHEMICAL PROPERTIES OF LIQUID PARAFFINS A N D PARAFFIN WAXES 3 1 and phenylalkanes The total hydrocarbon composition of the liquid paraffin is

listed in Table 1-9, showing that 60 compounds could be identified, among these

14 different n-alkanes, 28 iso-alkanes, 12 cycloalkanes and 6 phenylalkanes The

amount of non-identified hydrocarbons did not exceed 1.3 %

The authors also stated that the iso-alkanes contained in the fraction forming

no adduct with urea are monosubstituted methylalkanes, with the methyl group attached to one of the C, to C, carbon atoms The cycloalkanes contained in the fraction are rings of five or six carbon atoms, with straight-chain alkyl groups attached In the phenylalkanes present, the benzene ring is attached to the second carbon atom of the alkane

Paraffin waxes consisting of C,&30 hydrocarbons are mainly composed of n-alkanes Compounds containing rings, or branched at the end of the chain, are also present, but in small amounts and especially in the higher fractions

In microcrystalline paraffin waxes consisting of > C3,C3, hydrocarbons, obtained from fractions distilling over at higher temperatures or from vacuum distillation residues, the other than normal character dominates Hydrocarbons other than normal cover the total carbon atom number range from C30 to Cs0 n-Alkanes in microcrystalline paraffin waxes are also mainly within this range

In addition to n-alkanes and iso-alkanes, macrocrystalline and microcrystalline paraffin waxes contain naphthenes, especially alkyl-substituted derivatives of cyclopentane and cyclohexane Depending on the source of the crude and on the extent of refining, larger or lesser amounts of cyclic sulfur and nitrogen compounds are also present

The decisive factors determining the properties of low oil-content paraffin waxes are hence the distribution, by carbon atom number, of n-, iso- and cyclo- alkanes and their relative quantities This appears quite evident, knowing that substantial differences exist between the properties of isomeric n- and iso-alkanes

As an example, Table 1-10 (based on data by Mazee) records the physical prop-

erties of two n-alkanes and their iso-alkane isomers, both within the carbon atom number range of macrocrystalline paraffin waxes

To characterize the chemical composition of paraffin waxes some characteristic values for three microcrystalline paraffin waxes from different sources will first

be presented, based on data from Ridenour, Spilners and Templin These values

Table I-10 Physical properties of two n-alkanes and their branched isomers in the

range of macrocrystalline paraffin waxes

Boiling Formula point at

1 1 0 5 F

Alkane

Boiling Formula point at

1 1 0 5 F

Melting Density point; "C 1 di0 1

32

Refr

I PROPERTIES OF LIQUID PARAFFINS AND PARAFFIN WAXES

Aver Ring analysis (n-d-M) Corresponding

n-alkane Dens

= total ring content per molecule, R, = aromatic ring content per molecule,

R, = naphthenic ring content per molecule In the first eight distillation fractions

of the adduct-forming portion of sample A , the total ring content determined by the n-d-M method is less than 0.2 rings/molecule The value of R N in distillation fraction 9 is 0.4, in the distillation residue 0.8 According to infrared absorption

79.0 68.9 71.6 72.8 75.8 77.0 78.6 80.9 83.4 87.4 93.6

1.4422 0.7919 1.4374 -

(B) CHEMICAL PROPERTIES OF LIQUID PARAFFINS AND PARAFFIN WAXES 33

Ring analysis (n-d-M)

'%" 7O"C Wt RT I R k 1 RN

Table 1-13 Characteristics of the fractions obtained by molecular distillation

from the adduct-forming part of the microcrystalline paraffin wax

76.0 67.0 69.4 71.2 73.8 76.0 77.6 79.4 80.5 82.2

1.4410 1.4356 1.4368 1.4377 1.4390 1.4399

1 A 0 8 1.441 8 1.4425 1.4439

1.4400 1.4340 1.4363 1.4371 1.4377 1.4387 1.4402 1.4419 1.4435

1 A450

0.7882 0.7797

0.0 0.0

measurements this consists of monocyclic alkanes and their substituted derivatives

The adduct-forming portion of sample B, and its fractions have a similar composi-

tion, the differences showing only in the range of molecular weights and in the

total ring content of distillation fraction 9 and of the residue Fractions from

sample C have lower melting points and higher refractive indices than fractions

from samples A and B with identical molecular weights This indicates that

3

34 1 PROPERTIES OF LIQUID PARAFFINS AND PARAFFIN WAXES

sample C contains a higher percentage of iso-alkanes However, the slight differ- ences in the melting points demonstrate that these iso-alkanes are branched to a small extent only

The characteristics of the portions of the three samples forming no adduct with urea, as well as of their distillation fractions, are listed in Tables 1-15-1-17

It may be observed that the portion of sample C forming no adduct has a sub- stantially higher average molecular weight, a broader molecular weight range, a lower average melting point and a narrower melting point range than those of the other two samples This difference is in conformity with its composition: sample C

and its portion forming no adduct contains more branched alkanes and the share

of aromatic and naphthenic rings is higher than in sample A and B The ring

Table 1-15 Characteristics of the fractions obtained by molecular distillation

from the part forming no adduct of the microcrystalline paraffin wax

9.55

10.45 9.85 10.7 10.4 Distillation residue 20.8

63.0-65.0 51.0 57.0 61.0 66.0 66.0 69.0 71.0 72.0 68.0

1.4592 1.4580 1.4566 1.4556 1.4559 1.4567 1.4578 1.4595 1.4644 1.4677

0.8305 0.8291 0.8244 0.8243 0.8239 0.8246 0.8264 0.8310 0.8338 0.8440

1340 3.0 0.6 2.4

Table 1-16 Characteristics of the fractions obtained by molecular distillation

from the part forming no adduct of the microcrystalline paraffin wax

63.0-63.3 55.6 58.6 60.6 62.7 64.3 65.3 66.0 65.6

1.4617 1.4596 1.4559 1.4559 1.4562 1.4573 1.4583 1.4606 1.4695

0.8325 0.8304 0.8217 0.8217 0.8220 0.8245 0.8255 0.8306 0.8434

1.3 0.25

1.3 0.25 1.3 0.30

1.4 0.30 1.4 0.35 1.7 0.35 2.2 0.8

1.4 1.55

1.05 1.05

1 .00

1.10 1.05 1.35 1.4

(B) CHEMICAL PROPERTIES OF LIQUID PARAFFINS AND PARAFFIN WAXES 35

Table Z-17 Characteristics of the fractions obtained by molecular distillation

from the part forming no adduct of the microcrystalline paraffin wax

1 A563 1.4598 1.4644

The cited authors achieved further separation by thermodiffusion of the distilla-

tion fractions obtained from the part of sample A that forms no adduct As a result of subsequent analyses, they succeeded in determining the chemical compo- sition of this part of the sample They found that it consists of about 17 wt-% monocyclopentylalkanes, 24 wt- % monocyclohexylalkanes, 6 wt- % dicyclopentyl- alkanes, 20 wt- % dicyclohexylalkanes, 6 wt- % monocyclic aromatics, 5 wt- %

polycyclic aromatics and 22 wt- % polycyclic alkanes The distribution among

these compound types is shown in Fig 1-5, where, on the one hand, dicyclopentyl-

Distillation yield, wt-%

Fig 1-5 Distribution of compounds in the part forming no adduct of the microcrystalline

paraffin wax marked A

3+

36 I PROPERTIES OF LIQUID PARAFFINS AND PARAFFIN WAXES

and dicyclohexylalkanes, and on the other, aromatics and polycycloalkanes are combined into one group each

Bornemann and Heinze used the combined analytical procedure shown in Fig 1-6 for characterizing the composition of microcrystalline paraffin waxes Their starting material was slack wax In the first stage they prepared - by frac- tional crystallization - vaseline, plastic and hard microcrystalline paraffin wax (these terms correspond to the classification of Kreuder) The hard paraffin wax was then separated into several fractions by chromatography on columns filled with silica gel The iso-octane eluates were separated into portions forming adducts and forming no adducts, and these were subsequently subjected to further separa- tion by fractional crystallization from dichloroethane, by chromatography on activated carbon and silica gel, and by molecular distillation

The results that the cited authors obtained with petrolatum from the heavy distillate of Romashkino crude are presented in the following tables Table 1-18

Table Z-18 Main characteristics of products obtained by fractional crystallization

of a petrolatum from the heavy distillate of a Romashkino crude

Starting Characteristics

Part forming adduct with urea,

Part forming no adduct, wt- % wt- %

-

1.4497 0.8102

450 63.6 16.7

40 (cone)

25.5 27.4 72.6

69.7 20.7 1.4546 1 A430 0.8193 0.7977

422 535 40.9 63.4 18.1 14.0

550 77.9 14.4

9 1.7 84.5 15.5

shows the main characteristics of the products obtained by fractional crystalliza- tion from the petrolatum The hard paraffin wax fraction was separated by chro-

matography on 0.1-0.4 mm silica gel activated at 180 "C The fractions obtained

in this operation are shown in Table 1-19 The iso-octane eluates separated into adduct-forming and non-adduct-forming portions were further separated by fractional crystallization, by molecular distillation at 200-265 "C in a vacuum of

1 cPa, and by chromatography The narrow fractions obtained by these procedures were analysed by determining the usual physical characteristics (refractive index, density, melting point, etc.), the Hersch-Fenske data and the n, versus b.p dia- gram shown in Fig 1-7

Their experimental results can be summarized as follows The hard paraffin

wax studied consists of C,,-C,, compounds The n-alkane content represents 25

to 35 %, the majority of these being C,&, compounds The share of iso-alkanes

Slack wax from heavy distillate

separation on active carbon

Fig 1-6 Group analysis of microcrystalline paraffin waxes according to Bornemann and H e i m

8

w

4

38 I PROPERTIES OF LIQUID PARAFFlNS A N D PARAFFIN WAXES

Table 1-19 Characteristics of fractions obtained by chromatography on silica gel

of the hard microcrystalline paraffin wax (source: Romashkino crude)

Part forming a n adduct with

Part forming no adduct, wt- %

resinous substances around 1.5 wt- %

lC200 I / '

0 20 " 40 60 80

Boiling point, "C (1 cPa)

Fig 1-7 Part of the diagram of refractive index versus boiling point

A hard paraffin wax, B I-IV iso-octane eluates, C adduct-forming part of iso-octane eluate I,

D part of iso-octane eluate I forming no adduct

The authors of this book studied how and to what extent the chemical composi- tion of macrocrystalline and microcrystalline paraffin waxes from Romashkino crude is changed by the effect of de-oiling and subsequent refining by the hot

(B) CHEMICAL PROPERTIES OF LIQUID PARAFFINS AND PARAFFIN WAXES 39

Macrocrystalline light distillate

Table 1-20 Characteristics of slack wax and petrolatums from Romashkino crude

Microcrystalline Microcrystalline

petrolatum from petrolatum from heavy distillate residual oil

Macro- Microcrystalline

Colour index ASTM (1/4")

Extinction (Pulfrich filter 8, 100 mm)

_ ~ _ _ _ _ _ _ _

0.7683 2.75 48.5

27

8 +

1 7.8 1.4269 0.19 1.3

1 .o

0.7

319

0.8357 9.91 57.9

146

8

21 42.8 1.4604 0.89

480

20.0 6.0 3.9

0.8264 12.43 65.5

112 4.5+

6

23.7 1.4551 0.65

583

13.1 15.1 1.8

contact method The main characteristics of the materials investigated are shown

in Table 1-20 De-oiling was carried out at + 10 and +30 "C with methyl ethyl

ketone, hot contact treatment with 196 m2/g specific surface area activated clay

of the bentonite type The characteristics of the de-oiled products are listed in

Table 1-21 Those in Table 1-22 are of products refined by hot contact under

Table 1-21 Characteristics of the slack wax and petrolatums figuring in

Table 1-20 after deoiling

Colour index ASTM (1/4")

Extinction (Pulfrich filter 8, 10 mm)

19

1 0.85 0.7 1.4236 0.03 0.3 0.1 0.1

0.7635

341

37.5 66.8

28 8+

14.2 5.1 1.4360 0.21

0.7930

517

17.9 52.9 73.1 70.5

9 5+

5.0

1 .o

1.4391 0.17

694