Mobil Oil Corp. v. Amoco Chemicals Corp.

779 F. Supp. 1429, 1991 U.S. Dist. LEXIS 19021, 1991 WL 274841
CourtDistrict Court, D. Delaware
DecidedDecember 27, 1991
DocketCiv. A. 83-207 LON
StatusPublished
Cited by13 cases

This text of 779 F. Supp. 1429 (Mobil Oil Corp. v. Amoco Chemicals Corp.) is published on Counsel Stack Legal Research, covering District Court, D. Delaware primary law. Counsel Stack provides free access to over 12 million legal documents including statutes, case law, regulations, and constitutions.

Bluebook
Mobil Oil Corp. v. Amoco Chemicals Corp., 779 F. Supp. 1429, 1991 U.S. Dist. LEXIS 19021, 1991 WL 274841 (D. Del. 1991).

Opinion

OPINION

LONGOBARDI, Chief Judge.

The Plaintiff Mobil Oil Corporation (“Mobil”) alleges that Defendant Amoco Chemicals Company (“Amoco”) is infringing patents owned by Mobil. These patents cover compositions known as ZSM-5 zeolites and their use as catalysts. Amoco denies that it infringes Mobil’s patents and also alleges that Mobil’s patents are invalid.

I. TECHNICAL AND FACTUAL BACKGROUND

A. Zeolites

Natural and synthetic zeolites are crystalline materials with a variety of useful characteristics. They currently are used in a wide variety of applications including: catalytic cracking in the petroleum industry, catalysis of hydrocarbon reactions, drying of refrigerants, removal of carbon dioxide and sulfur compounds from natural gas, recovering radioactive ions from radioactive waste solutions, curing of plastics and removal of atmospheric pollutants. D.W. Breck, Zeolite Molecular Sieves 2 (1974) Defendant’s Exhibit (“DX”) 1122.

The study of zeolites began in 1756 with the discovery of stilbite, a naturally occurring zeolite. The word zeolite means “boiling stone” and refers to the fact that naturally occurring zeolites contain water which vaporizes or boils when the zeolites are heated. R.M. Barrer FRS, Hydrothermal Chemistry of Zeolites 2 (1982) (DX 1125); Docket Item (“D.I.”) 126 at 693.

Further studies indicated that zeolites exhibited other remarkable properties. In 1840, it was discovered that zeolite crystals could be dehydrated and then rehydrated without changing the transparency or morphology of the crystal. The adsorption of gases by dehydrated zeolites was discovered in 1909. In 1925, a publication taught that dehydrated chabazite, a naturally occurring zeolite, would absorb vapors of some liquids but not vapors of other liquids. D.W. Breck, Zeolite Molecular Sieves 14 (1974) (DX 1122). Researchers also discovered that certain zeolites, such as gmelinite and chabazite, had similar adsorption properties while other zeolites, such as mordenite, exhibited different properties. Id. at 18. The ability of certain naturally occurring zeolites to selectively adsorb certain vapors, as well as their ability to act as catalysts and cation exchangers, made them valuable candidates for commercialization.

These properties are largely attributable to the structure of the zeolites. Zeolites are crystals made up of three dimensional networks of atoms. These networks are largely open structures containing cavities and channels of various sizes. Currently at least sixty-four different zeolite networks or topologies are known to exist. W.M. Meier & D.H. Olson, Atlas of Zeolite Structure Types 1 (2nd ed. 1987), Plaintiff’s Exhibit (“PX”) 857. Any sample of a particular zeolite will always have the same topology as any other sample of the same zeolite.

In naturally occurring zeolites, the networks are primarily made from three elements: oxygen (“0”), silicon (“Si”) and aluminum (“Al”). More precisely, these three elements are arranged in tetrahedral units of SÍO4 and AIO4 and these units are linked together to form the network of the crystal.

In an individual SÍO4 tetrahedron, the silicon is at the center of the tetrahedron and is bonded to four oxygen atoms which make up the corners of the tetrahedron. An AIO4 tetrahedron is analogous except that aluminum rather than silicon occupies the center of the tetrahedron. The atom in the center of each tetrahedron was referred to as the “t-atom” by several of the witnesses at the trial and the Court will adopt that nomenclature.

These t-atoms and their corresponding oxygens combine in different ways to produce a variety of network structures. A *1436 visible zeolite crystal is made up of millions of repetitions of a basic network pattern. The smallest piece of the crystal that can be repeated to produce the entire network is called the “unit cell.” Therefore, the unit cell of a zeolite defines its crystal structure. Although the technique was not available when the study of zeolites began, today researchers can determine if a structure of new zeolite matches one of the known topologies. This is done by taking an X-ray diffraction pattern of the new zeolite and comparing it to known patterns inherent in other zeolites.

The composition of any given zeolite is not as constant as its crystal structure. Unlike compounds such as water or carbon dioxide, zeolites cannot be assigned specific chemical formulas. Each t-atom shares its oxygen atoms with an adjacent t-atom. The common oxygen atoms link the tet-rahedra into a network. When the t-atoms in a zeolite are solely aluminum and silicon, the ratio of the aluminum atoms plus silicon atoms to oxygen atoms is one to two. However, the ratio of silicon atoms to aluminum atoms may not be exactly the same for two samples of a given zeolite.

Originally, it was not possible to directly measure the aluminum and silicon content of zeolites. In order to measure the silicon and aluminum in a sample, the sample would be heated in the presence of air to convert the elements to their oxides. D.I. 126 at 633. Using this method, silicon is converted to silica, Si04 and aluminum is converted to alumina, A1203. Researchers expressed the amounts of silicon and oxygen in a zeolite sample in terms of a silica to alumina ratio and this practice is still the standard practice in the field. Id. at 635. In order to calculate the silicon to aluminum ratio for a sample, one must divide the silica to alumina ratio by two. It is also important to note that the high silica to alumina ratios indicate low amounts of aluminum and low silica to alumina ratios indicate high amounts of aluminum. 1

A discussion of zeolites would not be complete without referring to the non-framework components of zeolites, namely water and associated cations. If a zeolite is not dehydrated it will contain a certain amount of water within the channels and pores of the framework. Zeolites also contain positively charged species called cations. Zeolites require non-framework cations to maintain electrochemical neutrality. Oxygen ions each carry a formal charge of negative two. Silicon, when it is bonded to oxygen, generally carries a formal charge of positive four. In a zeolite with no aluminum atoms, the ratio of silicon atoms to oxygen atoms would be 1 to 2. Each silicon with its formal charge of positive four would balance two oxygen atoms with their individual formal charges of negative two. Therefore, such a zeolite would be electrochemically neutral.

The introduction of aluminum into the zeolite crystal structure makes things more complicated from the electrochemical point of view. Aluminum atoms in zeolites carry a formal charge of positive three. Unlike silicon, a single aluminum ion cannot completely balance the charge from two oxygen ions; one negative charge will remain. Therefore, the framework of a zeolite is generally anionic, that is, it carries a negative charge. Each aluminum t-atom contributes to this overall deficit of positive charges in the structure. In order to correct this deficit, zeolites contain non-framework positive species called cations. The *1437

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779 F. Supp. 1429, 1991 U.S. Dist. LEXIS 19021, 1991 WL 274841, Counsel Stack Legal Research, https://law.counselstack.com/opinion/mobil-oil-corp-v-amoco-chemicals-corp-ded-1991.