TECHNOLOGY
Sulfolane Finds New Uses in Extraction Shell plans to use sulfolane to extract aromatics; others will use Sulfinol process to purify hydrogen Later this year, one of Shell Oil's refineries near Houston, Tex., will begin using sulfolane in a modified extractive distillation unit for extracting benzene, toluene, and xylene from catalytic reformates. In another move related to commercial availability of sulfolane, Consolidated Mining & Smelting Co. of Canada, Ltd., Trail, B.C., will start to use Shell's Sulfinol process for purifying hydrogen which is used in the firm's ammonia plant. Several U.S. companies are expected to follow suit. These ventures will mark the first commercial use of these processes in the U.S. and Canada. The Sulfinol process, which uses sulfolane along with alkanolamines as the solvent system, removes contaminants such as carbon dioxide, hydrogen sulfide, mercaptans, and carbonyl sulfide from natural gas, hydrogen or synthesis gas, and, in some cases, refinery gas streams. In the extraction processes for lighter aromatics, such as the Udex, sulfolane (tetramethylene sulfone) can replace diethylene glycol and other glycols which are the solvents usually used for benzene-toluene-xylene extraction. The Udex process is a joint development of Universal Oil Products Co. and Dow Chemical Co. Now UOP is also Shell's exclusive licensing agent in the U.S. for the sulfolane extraction process. Shell Development worked out a commercial process for manufacturing sulfolane, and the solvent is now being made in commercial quantities at Stan-
low, England. Sulfolane is made by the reaction of sulfur dioxide with butadiene to form sulfolene, which is then hydrogenated to sulfolane. Shell plans to build a sulfolane plant in the U.S. when demand justifies it. The use of sulfolane as solvent for extracting aromatics offers several advantages, Shell claims. Sulfolane is more thermally stable, and a more selective solvent for aromatic hydrocarbons than is diethylene glycol. Also operating costs are cut by about 25% when sulfolane is used in existing Udex units which have been modified slightly. For new units the capital investment costs are about 25% lower because of an improved process sequence, which omits certain heat transfer equipment. Smaller separation, distillation, and extraction columns are used. A commercial refinery that uses sulfolane for extracting aromatics is now on stream in Stanlow, England. Shell Refining Co. revamped its Udex unit for use with sulfolane solvent system. The process is designed to recover 9 5 % of the feed aromatics from a light catalytic reformate at a purity of 99%. Two major changes had to be made in the Udex unit to switch to sulfolane—rectification of the extract for solvent removal, and application of the rectification column overhead water to raffinate water wash. Shell says that the capital expenditure is less than 10% of the original cost of the plant. Two major benefits accrued from
Sulfinol Process Costs Less Than Do Other Gas-Removal Processes in Making Hydrogen Sulfinol
Modified Carbonate
On-site capital cost, %
90
100
120
Operating cost,* %
95
100
200
Monoethanolamine
Steam-Methane Reforming
* Utilities, chemicals, operating labor, maintenance, process auxiliaries, taxes and insurance. Source: Shell Chemical
50
C&EN
MAY
18,
1964
the change at Stanlow for the 99% purity, high-octane blending stock. First, consumption of steam has been reduced by about 4 0 % . Second, effective capacity of the plant has been increased by about 2 5 % . However, Shell believes that with some additional changes to the extractor and the use of a rotating-disk contactor, an increase of 50% is possible. Another Shell refinery that uses sulfolane is also on stream in Rho, Italy. The start-up of Shell's refinery could well influence other refiners to install this process in the U.S. To date, emphasis has been on the use of sulfolane in manufacturing light aromatics from catalytic reformate fractions. However, other feedstocks can be used for aromatics production, and sulfolane looks attractive for other separations such as extraction of kerosine-range aromatics. In the nonpetroleum field, sulfolane extraction has potential for separating fatty acids into their saturated and unsaturated portions, as a reaction solvent, and as a solvent for polymer spinning. Removes Contaminants. The Sulfinol process, developed by Shell Development Co., is an economically attractive way to obtain sweet pipeline gas directly from a variety of acid gases, Shell says. Shell Development is the sole licensee of the Sulfinol process. By contrast with other available processes, the solvent system— sulfolane used along an alkanolamine— removes mercaptans and handles carbonyl sulfide without excessive amine degradation. Shell says that for instance, monoethanolamine (the solvent most often used) isn't very attractive for removing contaminants in very acid natural gases because of its high circulation and heat requirements. The modified carbonate process is frequently used for removal of carbon dioxide from synthesis gas, but the extraction has some of the same disadvantages as monoethanolamine. Also the carbonate process can't be used for stripping hydrogen sulfide from nitrogen gas. The Sulfinol process is also suited to purifying hydrogen gas streams generated by partial oxidation of heavy fuel such as with Shell's gasification process—used mostly in Europe. It is also suited to similar streams produced in steam-methane reforming—used mostly in the U.S. Economics of the process will be more attractive if the Sulfinol process
If you have a crystal dewatering problem... There are five different types of centrifuges you might use — a high-speed automatic batch type . . . a "pusher" . . . a conical s c r e e n . . . a controlled-speed automatic batch type . . . a solid bowl. All of them will "work/' But only one will give you your best performance/cost relationship. To be sure you get it, call on Sharpies. Because only Sharpies makes every type of centrifuge for dewatering crystals. Nearly 40 models and sizes, with uncounted variations to suit specific needs. Designing and building centrifuges better . . . and helping our customers get the right one . . . is our only business—has been for over half a century. Facts, figures and application assistance quickly at your request. Call your Sharpies representative or write to Sharpies, 2300 Westmoreland St., Philadelphia, Pa. 19140
SHARPLES* SEPARATION SPECIALISTS FOR THE CPI Representatives and Associated Companies Throughout the World
If you are working with Reactor pressure vessels Steam power plants Wave guide seals Nuclear apparatus Oxygen Helium Water Vessel enclosures Vacuum seals Steam connections Oil refineries
Chemicals and acids Engines: diesel, gas, turbine, jet Space test chambers Missile engines Solid propellants Liquid propellants Cylinder heads Hydraulic pressures Vapors and gases High octane fuels Oils and solvents
you need this FREE manual
A complete guide to achieving pressure tight joints a n d p e r m a n e n t non-corrosive seals. United's patented metallic "0"-rings withstand t e m p e r a t u r e extremes from —452° to 3000F. a n d pressures from 10 ~ 8 T o r r to 100,000 psi. U n a f f e c t e d b y corrosive chemicals, acids a n d gases. Unlimited range of sizes a n d shapes. W r i t e for your copy of this F R E E , helpful m a n u a l today.
unp UNITED AIRCRAFT PRODUCTS, INC. 1116 BolanderAve.,Dept. I, Dayton8,Ohio 52
C&EN
MAY
18,
1964
is used to remove hydrogen sulfide and carbon dioxide in the synthesis gas purification train, Shell believes. The Sulfinol process uses a conventional absorption and regeneration cycle like the one used in the aqueous alkanolamine process. The process involves simultaneous selective physical and chemical absorption of the acidic components in the sulfolanealkanolamine. The acidic components are subsequently released at ambient pressure and a temperature of about 150° F. The sulfolane-alkanolamine solvent is much easier to strip than is aqueous monoethanolamine since the temperature equilibrium for acid gas favors Sulfinol. The economic operating advantages of the process are due mainly to reduced solvent circulation and reduced consumption of utilities and chemicals. There is also less maintenance on this system. The gas is free of sulfur and mercaptans. Process Economics. Shell has estimated cost of its process compared to other processes based on relative rather than absolute bases. This is done because of variations due to local and other factors. U.S. standards are used in assessing capital costs. Shell has compared the actual capital costs of existing plants using conventional processes, and costs of the Sulfinol process are derived from these by applying well-established cost factors. Since nearly the same type of equipment is used in all cases, factoring is straightforward. On-site capital cost comparisons, using a steam-methane reforming process as the base, indicate that the Sulfinol process costs 10% less than the modified carbonate technique, 30% less than when using monoethanolamine. Operating costs for the Sulfinol process are 5% less than the modified carbonate technique, 105% less than the monoethanolamine process, according to Shell. Hydrocracking installations in the U.S. refineries, and the continuing growth of ammonia synthesis capacity, both in the U.S. and abroad, presage a very substantial demand for hydrogen. Extrapolation of present demands to 1970 indicates a potential expansion of as much as 4 million tons a year in U.S. ammonia capacity. U.S. hydrocracking capacity will exceed 350,000 bbl. per day. Hydrogen needed for this growth alone would be on the order of 1.5 billion standard cubic feet per day.
1963 DIRECTORY OF GRADUATE RESEARCH The newest edition of this unique directory is the sixth to be prepared by the ACS Committee on Professional Training It covers the 1961-62 and 1962-63 academic years and provides a useful reference to: • degrees available • fields of interest and publications of 4,152 faculty members in 297 departments or divisions of chemistry, biochemistry, and chemical engineering in United States universities offering the Ph.D. degree.
Under each department heading, degrees offered and fields of specialization appear first. Then faculty members are listed alphabetically with an up-to-date record on their education . . . general fields of major research interest... subjects of current research . . . publications during the past two years. With such explicit information you can clearly determine where your own field of interest is most actively represented.
If you counsel students, or seek an advanced degree yourself, or if you are interested in knowing the kind of research done in certain academic centers for whatever purpose, then this book will answer your questions and save you time.
655 pages.
Paper bound.
Order from: Special Issues Sales American Chemical Society 1155 Sixteenth Street, N.W., Washington, D. C. 20036
Price: $4.00
JAYFLEX DTDP in Vinyl Organosols for Prepainted Metals Use of precoated metals for a variety of finished products has more than doubled since 1960. The attraction of low finishing costs coupled with increased automation and préfabrication will continue to stimulate the growth in use of prepainted materials. But with the benefits of prepainting comes increasingly critical conditions with which the coatings formulator must contend. In addition to metal cleaning, bake, film thickness, gloss, hardness, flexibility and adhesion, the formulator must also consider difficulties that may come with shipping and storing the precoated metal—such things as pressure mottling of the coated coils. Because of their outstanding physical properties, one-coat organosols are becoming a larger factor in the coil coating industry. The elimination of a primer coat, normally required with a standard organosol, has been an important reason for their acceptance. The organosol gains its adhesive nature by incorporating into the formulation modifying resin systems that have exceptional adhesive properties, while keeping the coating's durability and good physical characteristics. In order to make vinyls organosols more economically attractive to the formulator without losing any of the benefits of property advantage, Enjay has investigated the possibility of substituting a less expensive plasticizer for the higher cost polymeries generally used. Proper plasticizer selection is extremely i m p o r t a n t in the primerless organosol formulation. A permanent type is essential because plasticizer volatility and extraction will adversely affect long-term durability in terms of film embrittlement and adhesion. While monomeric plasticizers have an economic advantage over polymeric plasticizer, low viscosity of formulated products is also
PROPERTIES OF RESIN PLASTICIZER COMBINATIONS Low Molecular Wt. Polymeric Plasticizer
Medium Molecular Wt. Polymeric Plasticizer
Medium High Molecular Wt. Polymeric Plasticizer
Jayflex Ditridecyl Phthalate
PVC Dispersion Grade Resin
100
100
100
100
Plasticizer
50
50
50
50
100,000
100,000
100,000
41,000
0.30
0.33
0.44
0.225
90
94
92
95
Brookfield Viscosity #4Spindle, 6 RPM7 @ 75°F (CPS) Cost of Plasticizer $/LB. Plast. Efficiency (PHR) DOP = 80
a plus factor. C-8 phthalates have always been considered too volatile for longterm outdoor exposure. In a typical vinyl organosol formulaPROPERTIES OF BAKED FILM WITH DTDP Adhesion Crosshatch, Cellophane Tape Impact Resistance 160 Inch Lbs Direct, Reverse Flexibility Conical Mandrel ι/β Inch, Simple Mandrel Gloss 60° Fadeometer 500 Hours Block Test 100 PSI, 135°F for 16 Hours
Pass Pass No Cracks No Cracks 15-20 No Fade or Discoloration No Tendency to Block
tion, Jayflex ditridecyl phthalate com pared favorably in all tests with a widely used, high-priced polymeric plasticizer. With no sacrifice of properties, DTDP is less expensive than the polymeric. In addition, the low viscosity of a DTDP plasticized organosol eliminates storage and handling problems and enables the formulator to increase the non-volatile content of the coating if he so desires. Vinyl organosols plasticized with Jay flex ditridecyl phthalate had superior mar resistance, and better dirt pick-up resistance. Impact resistance was also excellent and DTDP with its excellent
permanence did not detract from the adhesive properties of the organosol.
Enjay Announces Availability of Three Glycol-Ethers T o its line of surface coatings inter mediates, Enjay has now added three glycol-ethers—ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and ethylene glycol monobutyl ether. Glycol-ethers are useful in a vari ety of surface coatings—including uret h a n e s , acrylics a n d n i t r o c e l l u l o s e lacquers. Pick the glycol-ether you want— and get the bulk price on mixed ship ments with other Enjay products. For information on glycol-ethers—or any Enjay product —check and return the attached coupon. ι
1 Mail to: Coatings Intermediates Department Enjay Chemical Company, Rm.C16E18 60 W. 49th St., New York, Ν. Υ. 10020 Please send me information on the following: D JAYFLEX DTDP G ENJAY Glycol-Ethers NameCompany. Street .State
City
ENJAY CHEMICAL COMPANY, a division of Humble Oil & Refining Company
CNJAY
Enjay Coatings Intermediates —the starting point for better products alcohols · acetates · ketones · ethers · glycol-ethers · resins « plasticizers
Yttrium-Free Garnets Grown If you're looking for a
SOURCE for plasticizers, comonomers, plastisols, polyesters, and vinyl compounds, look to Rubber Corporation.
If you're looking for
SERVICE .. .experience-tested solutions, instrumental analysis, quality control, or custom-made formulations·, look to Rubber Corporation.
Λ
Once you've sent for . our booklets, V "RC Plasticizers and Comonomers" h-lInsular Polymers and Copolymers" and once you've talked to us, | ] ^ you'll stop looking.
i
RUBBER CORPORATION OF AMERICA New South Road, Hicksville, N.Y. Sales Offices: New York, Chicago, Boston, Akron
54
C&EN
MAY
18,
1964
Yttrium-free, single-crystal garnets for microwave devices are being grown by Bell Telephone Laboratories. A new technique which chemically re places yttrium with bismuth and cal cium has been developed by Dr. Sey mour Geller with the collaboration of H. J. Williams, G. P. Espinosa, and R. C. Sherwood, all of Bell Labs. Vanadium is also incorporated into the garnets by this technique. Pentavalent vanadium is balanced electrostatically with calcium, which, together with the bismuth, replaces the yttrium, Dr. Geller says. Unlike some other elements tested, the vanadium doesn't increase the garnet's anisotropy—differences in its magnetic properties in different directions. Single-crystal, yttrium-free garnets with vanadium have been used to make low-frequency (1700 megacy cles per second), low-field (300 gauss), low-temperature (4° K.) isolators. Because of their low anisotropy, the garnets are useful as low-frequency ferrimagnetic resona tors.
21 in the
No.
ADVANCES IN CHEMISTRY SERIES
OZONE CHEMISTRY AND TECHNOLOGY These 60 papers were presented at the International Ozone Conference in Chi cago in 1956. This event marked the first occasion for an international ex change of information concerning ozone in
both
science
and
technology.
It
brought together men from leading com panies, research institutes, and the Na tional
Science
Foundation,
differing
widely in their reasons for interest in
Cobalt Strip Slitted Expanded cobalt metal strips that have adequate ductility for being slit, cut, and formed are offered by Sherritt Gordon Mines, Ltd., of Toronto, Ont. The diamond-pattern product is made by slitting and then stretching 99% pure, 0.015-in.-thick cobalt strip. Individual diamond openings (about 170 per square inch) measure 0.187 by 0.062 in. along the axes. Expanded cobalt's ductility makes it suitable for applications in electron ics, metalworking, and the chemical industry where less-ductile wrought forms of pure cobalt cannot be used. Projected uses include support struc tures for catalysts and radioactive source material, magnetic screen shielding, and high-temperature cur rent-carrying applications. In catalyst-support use, expanded cobalt provides more support area per pound of metal than does woven screen or perforated metal, Sherritt Gordon says, making it possible to ex pose a greater catalyst surface area. As an electrical material, expanded cobalt has higher conductivity than does pure nickel. Its 2050° F. mag netic transition point is the highest known, the firm adds.
ozone but in a position to gain from a comparison of experience.
Major areas covered in their dis cussions were ozone chemistry . . . high concentration ozone . . . ozone technology . . . ozone analysis . . . organic chemistry . . . atmospheric ozone... ozone formation in electric discharge . . . ozone toxicity and ster ilization . . . reaction kinetics... water purification. Once primarily an important reagent of the organic chemist, ozone now claims the interest of meterologists, photochemists, organic and analytical chem ists, and plant physiologists. This vol ume provides a focal point for varied approaches to its use and development.
465 pages.
Cloth bound.
Price: $7.00
Order from: Special Issues Sales American Chemical Society 1155 Sixteenth Street, N. W. Washington 6, D. C.
