MEETING R E P O R T S
Division of Refining, American Petroleum Institute the continuous x-ray radiation from a copper x-ray diffraction tube, in combination with a modern commercial x-ray spectrometer, it is possible to make x-ray absorption measurements on materials as a continuous function of monochromatic wave length. By making measurem&ts near and on each side of an absorption edge, a specific analysis for the element characterized by the edge is possible. At the higher concentrations, the method is preferred to x-ray fluorescence because of the absence of a matrix effect. It is not so sensitive as fluorescence at the trace level. Calibration curves and method of measurement are presented for the determination of molybdenum and zinc. The calibration measurements can be used to analyze liquid hydrocarbons or catalysts. The method is applicable to elements above titanium in the periodic table.
21st Midyear Meeting of the Division of Refining, American Petroleum Institute, will be held in Montreal May 14 t o 17. Papers to be presented include the following. Other sessions include papers on instrumentation and computers. HE
T
Trace Analysis Symposium Spectrophotometric Determination of Chloride, Bromide, and Iodide. F. w. CHAPM~N, JR.,AND R. M. SHERWOOD, Atlantic Refining Co., Philadelphia, Pa. The petroleum refiner has known for years that trace amounts of metals in petroleum are harmful to various catalysts. More recently it has been found that certain nonmetallic elements such as chlorine can also inhibit the performance of catalysts. Unfortunately, there has been available no accurate and simple method by which very minute quantities of chlorine can be determined in petroleum products. As a result, needless losses of higher quality products have been encountered in the refinery. The method presented here can determine less than 1 part of chlorine, bromine, or iodine in 1,000,000 parts of gasoline. Such a determination will enable a refiner to keep his catalysts from contact with this harmful material.
Determination of Trace Amounts of Lead in Gasolines and Naphthas. M. E. GRIFFINGI, Ethyl Corp., Detroit, Mich., AND ADELE ROZEK,L. J. SNYDER, AND S. R. HENDERSON, Ethyl Corp., Baton Rouge, La. The poisoning effect of heavy metal ions on platforming catalysts is well known. The increasing use of these catalysts for upgrading gasoline and naphtha has resulted in a need for a rapid and accurate method for the determination of 10 to 100 parts per billion of lead. Because the same pipelines, trucks, and storage tanks may be used for both leaded and nonleaded fuels, it is necessary to analyze each shipment and plant feed stream before charging the catalyst. The method used must determine both inorganic lead and tetraethyllead. Two analytical methods have been developed, both of which are modifications of dithizone colorimetric procedures. One is a twocolor method involving the use of a spectrophotometer, and the other is essentially a one-color method involving the use of a color comparator. The former is more suitable for use by laboratories with specialized equipment for the simultaneous analysis of a number of samples; the latter may be applied in a refinery or field situation using very simple equipment. The accuracy of each method is 10 parts per billion.
Determination of Trace Amounts of Arsenic in Petroleum DistilR. E. SNYDER, AND R. 0. CLARK, Gulf lates. N. C. MARANOWSKI, Research and Development Co., Pittsburgh, Pa. Arsenic poisons platinum-containing reforming catalysts. Numerous methods have been devised for refining control in the selection of charge stocks for reforming from the standpoint of their arsenic content. Nearly all of these procedures employ prior treatment of the sample to concentrate the arsenic in a form so that the well known Gutzeit test can be employed. Some of these methods gave results that did not agree with the known arsenic content of standards prepared synthetically from triphenylarsine and arsenic-free naphtha. Other procedures appeared to lack sufficient sensitivity t o be used in pilot plant work in which it was desired to discriminate between two or more stocks whose arsenic contents were nearly the same. A method which overcomes these shortcomings is based upon destructive digestion of the sample with acids and subsequent isolation of the arsenic as the colored complex with mercuric bromide in a paper disk. The intensity of the resulting color is measured with a spectrophotometer, using a reflectance attachment. The reading is converted to a value for arsenic by a means of a previously prepared calibration curve. The test can be performed routinely by nontechnical personnel and is applicable to stocks containing arsenic of the order of 1 p.p.m. It has been in use for nearly 2 years and has satisfied the requirements of reliability, discrimination between stocks of nearly the same arsenic content, and speed.
Determination of Water in Methane and Ethanethiol. G. MATUnion Oil Co. of California, Brea, Calif.
EUYAMA,
Mercaptans are a vile smelling nuisance in petroleum. To prevent pollution of air in refining operations, oil companies isolate these materials and dispose of them. One way of disposal is by selling these materials, which are used as odorants in domestic fuel gases and as starting materials in making other useful chemicals. In order to sell mercaptans, however, it is necessary to know their purity. Chemists at the Union Oil Co. of California have devised a simple, rapid method for determining the water content of methyl and ethyl mercaptan.
Determination of Trace Amounts of Total Nitrogen in Petroleum Distillates. G. R. BOND,JR.,AND C. G. HARRIZ, Houdry Process Corp., Marcus Hook, Pa. Determination of Trace Amounts of Carbon Monoxide in Gaseous Hydrocarbons. K. H. NELSON,M. D. GRIMES,D. E. SMITH,AND B. J. HEIXRICH, Phillips Petroleum Co., Bartlesville, Okla.
The rapidly increasing interest in methods for determining low concentrations of nitrogen in petroleum charge stocks used in catalytic conversion processes is clearly shown by numerous recent publications. Honrever, very few satisfactory procedures have been developed to cover samples containing less than 30 p.p.m. of nitrogen. The authors have developed a unique method whereby it is possible t o concentrate the nitrogenous impurities from large samples onto a small column of silica gel. This gel is then treated by customary Kjeldahl analytical procedures to determine the amount of such nitrogenous impurities present. N o unusual laboratory equipment is required. X-Ray Absorption Edge Spectroscopy as an Analytical Tool. Determination of Molybdenum and Zinc. ROBERTE. BARIEUA, California Research Corp., Richmond, Calif. An old elemental analysis scheme combined with modern instrumentation gives a convenient, accurate method of analysis. Using
918
Information as to the amounts of carbon monoxide present in gaseous hydrocarbons can be of great importance. The yield of products and the reactivity of catalysts in many petrochemical processes may be materially affected by trace quantities of this contaminant. Suitable analytical procedures do not exist for the determination of a few parts per million of carbon monoxide in gaseous hydrocarbons. Generally, the methods lack sufficient sensitivity, or the hydrocarbons react with the reagents. A distillation-spectrophotometric method has been successfully applied t o the determination of 0 to 100 p.p.m. of carbon monoxide in hydrocarbon gases, with an accuracy of 1 to 2 p.p.m. In this procedure, the carbon monoxide is separated from the interfering hydrocarbons by a low temperature fractional distillation after the addition of methane. The carbon monoxide is then measured using an iodine pentoxide-spectrophotometric technique.
*
V O L U M E 28, NO. 5, M A Y 1 9 5 6 General Session on Analytical Research Application of Vapor-Phase Chromatography to the Analysis of Liquid Petroleum Fractions. D. H. DESTYAND B. H. F. WHYMAN, British Petroleum Co., Ltd., Sunbury-on-Thames, Middlesex, England. In this day of atomic reactors, electronic brains, and other advanced technology, we seldom hear of scientists turning in their more complicated tools for simpler ones. However, a new technique for analyzing gases and liquids, called “vapor-phase chromatography,” may prove t o be the exception. Though no one intends junking his multithousanddollar equipment for doing such things, analytical chemists are looking toward vapor-phase chromatography as a rapid inexpensive method for determining the composition of natural gas, gasolines, and other products-even of smog. The paper presents an example of what vapor-phase chromatography will do. The authors report successful separation and analysis of hitherto unidentified trace impurities present in nearly pure materials such as octane number reference fuels. Quantitative Analysis of Organic Disulfides. R. L. HUBBARD,
m7.E. HAINES,AND J. S. BALL,Petroleum and Oil-Shale Experiment Station, U. S. Bureau of Mines, Laramie, Wyo. A new, fast, and simple method for determining disulfides in petroleum products was developed. Disulfide determinations are important in product control, particularly in “sweetening” processes. The new method was tested, together with three older methods, for its reactivity toward disulfides of various structures. It was found t o be superior to older methods when applied to disulfides in the gasoline boiling range. Determination of Fuel Oil Stability to Optical Density Measurements. W. H. ARMSTRONG, D. MILSOM,H. P. HEBERT,AND A. R. RESCORL.4, Cities Service Research and Development Co., New York, N. Y. For the past number of years a considerable amount of research has been conducted to develop a satisfactory method for measuring the storage stability of distillate fuel oils. Several methods employ filter pad discoloration, filterability, and actual insoluble determinations by gravimetric procedures. A method for determining the insoluble content of an oxidized fuel oil by use of absorbance consists of measurements employing a I-cm. light path and 500 mp on oxidized oil samples before and after filtration through a fine sintered-glass filter (4.5-5 microns). Correlations have been established for determining the insoluble content with an accuracy equivalent to the gravimetric procedure from the difference in absorbance on the filtered and unfiltered samples. The correlation established between absorbance and insoluble content has been developed, using oils from varying types of crudes and oxidized over a range of temperatures. Additional correlations permit the establishment of predicted storage time at ambient storage.
Rapid, Precise Micro Vapor Pressure Method. A. Y . MOTTLAU, Products Research Division, Esso Research and Engineering Co., Linden, N. J. To manufacture motor gasolines of high quality, the refiner must build into them many important characteristics. Of these characteristics, vapor pressure is one of the most critical from the consumer’s standpoint. There is a desirable vapor pressure for each season of the year, for each geographical location. If the vapor pressure is too high for the air temperature, the customer’s car may vaporlock. If the vapor pressure is too low for the air temperature, the car will be difficult to start and warm up. Vapor pressure is also an important property of many other fuels. The precise adjustment of fuel vapor pressure will be made much easier by a newly developed device for measuring it. The new vaporpressure method has five times the accuracy of the old method, greater speed, and an improved sample handling procedure. This means improved performance for the consumer’s equipment and a savings in money to the refiner. Another big advantage of the new vapor-pressure measuring apparatus is the small amount of sample required to make a measurement. Only 1 cc., now used about 0.034 ounce, is needed. The apparatus requires over 130 times this amount. This will be a great help t o the researcher who oftentimes would like to measure the vapor pressure of very small samples obtained from laboratory scale counterparts of the huge refinery stills and cracking units. Combustion and EDTA Titrimetric Determination of Total Sulfur in Petroleum Products. 0. N. HINSVARK AND F. J. O’HARA,The Girdler Co., Louisville, Ky. An improved method, applicable to control procedures, for the determination of sulfur in petroleum samples permits determination
919 of all types of sulfur which might be present in a wide variety of sample materials ranging from low boiling naphthas t o high boiling coker gas oils. In general, the sample is aspirated into an oxyhydrogen flame of a Beckman atomizer burner and burned. As products of combustion are formed, they are swept by air into a hydrogen peroxide scrubber, where oxides of sulfur are converted t o sulfate. The sulfate formed in the scrubber is then measured by adding an excess of barium acetate and determining the excess barium by an EDTA titration. Samples covering a wide range of concentration from 100 to several thousand parts per million of sulfur have been successfully analyzed without danger of interference from halides or nitrogen in the sample. An error of f 1 6 p.p.m. is expected at the lower level with a slightly greater value at a higher level. By combining the combustion procedure and the highly selective titrimetric determination, a single reliable value can be obtained in about 45 minutes. Fluorescent X-Ray Spectral Analysis of Powdered Solids by Matrix Dilution. E. L. GUNN,Humble Oil and Refining Co., Baytown, Tex. Present-day petroleum technology requires the fastest and most precise analytical tools available for determining elements in varied substances encountered in the industry. The determination and control of elements are important because in some materials the presence of certain elements is highly detrimental, whereas in other materials elements occurring as specific compounds are very useful for enhancing the manufacture or final quality of a finished product. In recent years a number of rapid precise instrumental techniques have become available for inspection of the materials of petroleum refining. The x-ray fluorescent spectrograph is in the forefront of new instruments for elemental analysis of such materials. Basically, the x-ray fluorescence spectrograph consists of a highpower x-ray tube, the beam of which causes the elements in a specimen to emit their own characteristic x-rays or to fluoresce, a diffracting device to separate the x-rays into their respective unique wave lengths, and a device to detect and measure each wave length. The measurement of an element is independent of the manner of chemical combination with other elements but not of their mutual presence in the substance. The elements influence each other in such a way that the intensity of x-rays emitted by a given element is not a direct measure of its concentration. This paper describes a technique for lessening or eliminating this effect so that a number of elements coexisting in a powdered solid can be measured with reasonable accuracy. Determination of Calcium or Zinc Additives in Lubricating Oils and Concentrates by an EDTA Titration Method. P. B. GERHARDT AND E. R. HARTXANN, Products Research Division, Esso Research and Engineering Co., Linden, N. J. In many chemical and petroleum processes it is important to know when a particular unit operation is completed or when to proceed to the next operational phase. The stepwise following of a process to establish the quality of an intermediate or end product is commonly referred to as plant control. Although most chemical methods of analysis are time-consuming, they nevertheless can be used to control a batch process. How can these methods be used to control a continuous flow operation? As more manufacturing procedures are converted from batch t o continuous flow operations, this question assumes greater importance. The most satisfactory solution to the problem is t o develop rapid methods applicable to control of a continuous process. Chemists at the Esso Research and Engineering Co. have developed a rapid method for determining either calcium or zinc. This can be used to control additive manufacturing plants or the blending of lubricating oils. The procedure consists of a direct titration of the metal in an acetone solution of oil with an organic complexing agent. With this procedure it is possible to complete an analysis in about 20 minutes, as compared to 4 hours by conventional methods. The method has been used successfully t o control the manufacture of various additives and the blending of many lubricating oils with additives containing calcium or zinc.
Society for Analytical Chemistry meeting of Microchemistry Group, held January 27 in A London, the following papers were presented and discussed : T THE
Microchemical Methods in the Art Gallery and Museum. A. E. WERNER,Research Laboratory, British Museum.
