Petroleum. Physical properties - Analytical Chemistry (ACS Publications)

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Physical Properties,. The measurement of surface area of catalysts utilizing the gas chromatographic technique continues to be reported as by Chu (6L), Kuge and Yoshikawa (16L), and Liu et al. (17L) as does the x-ray diffraction technique by Keely (15L). Rapid methods using a simple calorimeter has been studied by Taylor (2%) and the Haul and Deu mbgen apparatus for surface area has been studied by Grundke and Frenzel (11L). Determination of the total metallic area of supported catalysts using chemisorption of hydrogen ar d carbon monoxide also received further attention by Germain et al. (91,). In similar type studies, Weigel et al. ( 2 t Z ) compared the BET and small-angle x-ray scattering techniques for absolute values and other information that could be derived from the data. A rapid, continuous flow method for the pore size distribution of catalysts has been described by C'ahen and Fripiat (4L). And Harris (191;) discussed the source of error in the calculation of pore size data from nitrogen isotherms. The density of porous solids by immersion in mercury in a pycnometer has been published by Cartan (5L) and a mathematical treatment was developed by Princon (19L) for coincidence corrections necessary in determining particle size distribution of catalysts using the Coulter counter. Miscellaneous. A :,tudy of the distribution of coke on catalyst beads as a function of the radiIs of the beads has been reported by Galimov et al. (8L); two different techniques for measuring the coke were evaluated

PhysicaI Pr pert ies 01

R . C. Vollmar, Standard Oil Co. of California, Richmond, Culif.

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(,%-If) studied flow time measurements in Ostwald viscometers tilted out of the vertical; they found variations c,in be explained as a function of the geometry of the viscometer. An empirical formula developed by Bondarenko (1O.V) correlated rate of slipping of a drop of liquid along a vertical filament with the viscosity of the liquid. Results compared favorably with measur1:d data in an Ostwald viscometer. Kinoshita and Onoyama (27M) postulated that surface actk e material from solvent refined oil adsorbed onto capillary walls, resulting in rtbduced effective bore size of the tube for subsequent tests. Flow rate changed gradually with repeated measurements on the same oil. A two-way capillary viscometer measuring bulk viscosity a t shear rates from less than 0.1 to over 1,000,000 per second and pressure drop up to 1000 psi was AKGTON AND VAUGHAN

described byTzentis (65112). After Calibration with Newtonian oils it was also applied to nowNewtonian salt solutions of polyacronitrile. Lim and Johnson (SOM) made precise measurements electronically of the time required for commercially available solid steel balls to flow through a known distance in liquid samples. Seibert, Johnson, and Stross (5111.1) adapted falling ball viscometry for more rapid routine use. They found good agreement with capillary viscometry with precision largely determined by the weight range of the balls. A new constant rate of flow viscometer described by Bianchi, Patrone, and Babini (7M) permitted static measurements of dilute polymer solutions over a wide velocity gradient range even a t high temperatures and under pressure. Use of the falling cylinder for nonNewtonian fluids was evaluated by Ashare, Bird, and Lescarboura ( 4 M ) . The non-Newtonian viscosity is estimated by treating the velocity-of-fall measurements by a differentiation procedure. Billington (8M)developed a coaxial cylinder viscometer for use under oscillatory and transient conditions as well as steady-state conditions. The timedependent solutions to the shear stress us. shear rate relationships were confirmed on a series of Newtoniar, lubricatr ing oils. Ramarkrishna (46M) made measurements of absolute viscosity by three computational methods based on the rotation of a cylinder suspended in the liquid by a wire. Equations for the velocity distribution and couple when a sphere is rotated in an inelastic nonNewtonian fluid were presented by Bourne (11 M ) . He covered their application to the measurement of fluid parameters at low shear rates. Jaffe and Ruysschaert (dlJ2) described a recording rotational viscometer with glassladen Teflon cylinders; accuracy and precision are discussed both for water and benzene. An extension to power-law fluid 3f Lewis' theory for rolling ball viscometers was presented by Bryd and Turian ( 1 Z M ) . They found a correlation of the speed of the rolling ball with fluid density and with physical and geometrical parameters when applied to non-Newtonian flow. A rolling ball viscometer for use a t temperatures to 400' C under pressures to 5 kilobar was developed by Harrison and Grosser ( I S M ) . Pressure medium is compressed argon and data covers glycerol a t 75' C. Marcelin (36M) designed a microviscometer consisting of a collar centered around a conical wedge of a very small conical angle where the thickness of the oil film depends on the depth of the wedge in the collar. His data showed viscosity coefficient to vary with film

thickness. He suggested (37M) the lubricant films consist of monomolecular layers on the solid surfaces, dense stratified layers, then diffuse stratified layers separating the dense layers and the bulk liquid. The effect of the structural changes under varying lubrication conditions is discussed. A series of equations covering the relationship of pressure and viscosity were developed by Amirbekov (3M). The viscosity of oil emulsions was reported by Muratova and Korobkova (41~12) ; they used a rheoviscometer in the form of a balance. The shear stress of oil emulsions was compared with their viscosity by adding weights to a tray attached to the balance arm of the viscometer. At above 40' C, the viscosity did not depend on shear stress and the liquids were Newtonian. Porter, Klaver, and Johnson (44M) developed a recording high-shear viscometer for measurements near a million reciprocal seconds. Accurate measurements were made a t shear rates of 500 to 2 million per second within an extended temperature range of -20' to 150' C. Viscosity range varies inversely with the shear rate selected for measurement. The shear-rate range 1s greater and its upper limit higher than previously reported. ii simple flexible viscometer for testing pseudoplastic liquids a t pressures as high as 1500 psi was described by Ram and Tainir (45-11). Equations and nomographs are given for designing viscometers or for selecting operating conditions with an existing one. Freund, Csikos, and Nozes (16-11) studied anomalous flow behavior of lubricating oils and slack wax a t low temperatures. No clear-cut relationship could be obtained between instantaneous shear stress values or shear rates and the corresponding rheological conditions. 4 comparison of the (U.K.) Sational Physical Laboratory and the (C.S.) National Bureau of Standards viscosity scales reported by Daborn (Id-lI), showed results agreed with NBS values by 0% to +0.5%. A 10-year test for stability of viscosity of petroleum reference oils was carried out by Weber (56M). Samples exposed to daylight showed more viscosity increases than those kept in the dark; little effect resulted from subjecting another series of samples to temperature variations. An improved equation for converting Engler to Kinematic viscosity was reported by Martens (38-V). It is recommended particularly for Engler values below 2.5. A circular slide iule which can be used to convert viscosity units betneen Kinematic, Engler, Redwood, and Saybolt nas reported in Science Lubrication (52"). This nomogram developed by Xngleroth may also be used for determining viscosity index and SAE classifications. Nagypal (49M) reported a linear relation between the cube VOL. 39, NO. 5, APRIL 1967

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root of the viscosity logarithm as expressed in Engler degrees and the ratio of components in mineral oil blends. Wright (57M) reviewed existing scales for expressing the viscosity temperature relationship of commercial lubricants, particularly VI, and proposed a new Viscosity Index extension (VIE) for use above 100 VI. The new scale eliminates anomalous reverse curvatures and gives approximately constant VI for all numbers of a series. I t has subsequently been incorporated into ASTM Method D2270, Calculating Viscosity Index from Kinematic Viscosity. Zuidema (58M) discussed the effect of precise temperature control on viscosity with particular attention to use of viscosity temperature charts described in ASTM Method D341, Standard Viscosity-Temperature Charts for Liquid Petroleum Products. He also covered some aspects of viscosity index and deviations from linearity. "Slope Index," that is the slope common to a family of straight parallel lines obtained by plotting viscosity-temperature relationships for members of a naturally homologous group of mineral oils, was prepared by Roelands, Blok, and Vlugter (47Jf) as a new viscosity temperature criterion. A low slope index corresponds to a high dynamic viscosity index. Saal (50M) prepared a theoretical review of the principles underlying the various systems of classification of lubricating oils according to their viscosity-temperature relation. A method for measuring vapor pressure in the range 10+ to 10-' millimeter Hg using an effusion manometer system has been suggested by Morecroft ( Q O M ) . Vapor pressure is obtained by measuring the recoil force produced by vapor effusing through a small hole into a high vacuum. Bell (6M) working in the same area, measured volatility of high boiling petroleum products in lubricating oil range using a saturator containing the sample over which a slow stream of nitrogen is passed. Flame ionization detector technique was used as a measurement of weight of vapor removed from the sample. Brzoska ( I S M ) worked on low vapor pressures of diffusion pump oils. The method is applicable where a low flow rate of vapor from sample to vacuum pump can be maintained and regulated. Saturated vapor pressure of lubricants in which the oil or grease sample is vaporized in a bulb in an insrt gas atmosphere was carried out by Martynov and Morozova ( S 9 N ) . They reported saturated vapor pressure of a grease is practically equal to the saturated vapor pressure of the base oil. Popov, Tsederberg, and Morozova (4SM) worked on thermal conductivity of diesel fuel and lubricants using a heated tube with a platinum fiber passing along its axis. Jobst (23M) de178 R *

ANALYTICAL CHEMISTRY

scribed a nonstationary absolute technique for measuring the thermal conductivity of aliphatic compounds by measuring temperature of a uniformly heated electric wire immersed in the sample. Correlations are presented for water, glycerol, ethanol, gasolines, and paraffins. A simple device for measuring thermal conductivity of liquids with moderate accuracy was employed by Jamieson and Tudhope (22M). A steady-state hot-wire method is used with a straight-platinum-wire conductivity cell and temperatures from 0 to 750 c. Dukhovnyi (15M) determined molecular weight cryoscopically with improvements including automatic measurement and recording of crystallization temperature. Kemeleva and Bekturov (24M) determined molecular weight of tar separated after oxidizing heavy petroleum residues Osmometric, cryoscopic, and viscosimetric measurements were carried out in benzene solution. A vapor pressure osmometer was used by Kume and Kobayashi (28L1f) to measure molecular weight of polybutadienes. Lindhe and Thorsson ( S I M ) lectured on the aniline point as a measure of the content of aromatics in mineral oils and the aromatic content and hydrocarbontype analysis of low-boiling mineral oil fractions. Reversing the usual process of determining other characteristics from aniline point, Hollinghurst (1OM) has prepared nomograms in which the aniline point is given either as a function of viscosity and VI or gravity and viscosity. Mackle and McClean (34X) extended previous work with refinements and improvements of apparatus for measurement of vaporization heats by gas liquid chromatography. Results on thiaalkancs were in good agreement with values obtained by twin ebulliometry as well as other empirical methods. A single stage centrifugal molecular still was used by Thomas (54M) for distillation of lube oils. Results were compared with those of a high vacuum pot still. Kerenyi and Borzsonyi (25-If) described glass distillation equipment suitable for recording the equilibrium boiling point curve both a t atmospheric and reduced pressures. Aleksandrova and Zykov ( I M ) used a 30-plate column for determining true boiling point curves of heavy fractions boiling in the range of 250-550' C, incorporating several automatic features. The importance of intervals of time and temperature increments in interpreting distillation data when using a single stage centrifugal still were discussed by Hickman and Thomas (19M). Barrall, Porter, and Johnson ( 6 M ) developed a micro boiling point technique by differential thermal analysis. Boiling points were obtained either by direct extrapolation of indi-

vidual thermograms or by bracketing samples between API standard hydrocarbons. The method has been used for high-resolution gas chromatographs. Green, Schmauch, and Worman (17M) used a gas chromatographic technique to simulate distillation equivalent to a 100-theoretical plate distillation. This was applied to distillates with boiling points up to 1000' F and to samples containing as much as 85y0 nonvolatiles. Bodan and Boichuk ( 9 M ) developed a rapid method for determination of density of liquid and solid products where refractive indices are measured on binary mixtures. Shraiber and Kukolenko (5SM) described a method for the precise measurement by pycnometer of density of liquids such as xylene isomers within a broad temperature range. Russian workers reported on cryoscopic methods for determining purity of aromatics. Mamedova, Akhmedov, and Aliev (35M) published work on xylene isomers featuring sealed ampules for avoiding moisture problems. The same group (1M)extended their work to doubly sublimed and recrystallized naphthalene. Lyashkevich ( S d M , S S M ) studied the influence of several variables on precision and developed a polymicro method applicable to samples of several hundredths of a gram and a t a temperature range of between -170' and 1-350" C. Ross and Dixon (48M) modified previously used techniques in the purity analysis of highly purified material by time-temperature cryometry. Dielectric cryometry was used by Ross and Frolen (49M); they suggest this might be adaptable for automatic control of temperature within extremely narrow limits. Kieffer et al. (16,M)used thermal analysis for the determination of the purity of very low melting hydrocarbons with a sensitivity greater than gas chromatographic analysis for trace contaminants.

Analytical Instrumentation W. V . Cropper, Precision Scientific Co., Chicago, 111.

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DEVELOPMENT of automatic types of instruments for petroleum analysis and testing continues strongly. Laboratory instrumentation has received the major share of attention; new in-stream analyzers have appeared, and previously developed instruments are finding more numerous and wider application. Among elemental analyses, automatic determination of carbon, hydrogen, and nitrogen has received greatest attention. These elements are measured with exHE