ENVIRONMENTALLY FRIENDLY TERNARY TRANSPORTATION FLEX-FUEL OF GASOLINE, METHANOL AND BIOETHANOL

BACKGROUND Petroleum based gasoline for cleaner and more efficient burning generally necessitates either high octane alkylate or oxygenate as well as other octane number enhancing additives. Many of these additives such as tetraethyl lead and other organometallic additives were, however, phased out because of their recognized environmental and health hazards. So were some petrochemical based oxygenates, such as MTBE, methyl-tert-butyl ether. Gasoline and any hydrocarbon fuel upon its combustion transform its carbon content into carbon dioxide (a recognized major greenhouse gas contributing to man caused global warming). There is consequently an increased interest in the use of bio fuels, mainly bioethanol.

Because the use of carbon based transportation fuels is one of the major-sources of man caused global warming, the use of bio fuels, specifically of bioethanol, is gaining significant use as any plant life or crop is a natural way to recycle carbon dioxide. Bioethanol produced by fermenting varied plant life and crops (corn, sugar cane, etc.) derives its carbon content by recycling atmospheric carbon dioxide via photosynthesis (using water and sun's energy) and thus is a renewable carbon fuel. The production of bioethanol, however, itself necessitates substantial energy (use of nitrogenous fertilizers, irrigation, operating varied machineries (tractors, trucks, etc.) to the energy need of the fermentation plants of crops, various plants, even cellulosic materials, etc.). Further, ethanol is miscible with gasoline only when it is dry, thus preventing its transportation via pipelines, even trucking of higher blends with gasoline, etc. It is therefore necessary to dry (dehydrate) ethanol from any water and handle it accordingly. The biofermentation process further also produces large amounts of carbon dioxide.

The use of binary transportation fuel mixtures of gasoline and methanol (such as M20 and M85) as well as gasoline and ethanol (such as E85) is well known and used at different locations (US, California, Brazil) at times. A ternary fuel mix called MEG (33% CH ₃ OH, 60% ethanol and 7% gasoline) was also used in Brazil (San Paulo area) in the late eighties and early nineties. MEG was introduced to overcome temporary shortages of ethanol at the time in Brazil and served to provide of usable alcohol fuel.

Presently, bioethanol based binary gasoline flex-fuel such as E85 and E20 (containing 85 or 20% ethanol, respectively) is attracting much current interest as a means to decrease dependence on depleting oil reserves and importation of oil from countries still possessing

substantial oil resources. In the US, bioethanol is primarily produced from corn, whereas in Brazil and other tropical areas sugar cane is the source. Bioethanol used in binary fuel mixes with gasoline must be dry (anhydrous) to avoid phase separation. This not only necessitates more expensive production involving an additional dehydration step (distillation only gives a 96% ethanol, 4% water azeotrope mixture) but poses significant difficulties in transportation (making pipelining and other usual bulk transportation inconvenient). Even pre-mixing with gasoline in refineries is not feasible. Thus, more efficient and economic improvements are needed, and these are now provided by the present invention.

US Patent Application 2006/0235091 discloses the use of methanol as a way of chemically recycling carbon dioxide from industrial or natural sources producing useful new fuels and materials while decreasing man caused atmospheric excess carbon dioxide and thus mitigating global warming. This application teaches that methanol can be used as a fuel by itself or in combination with gasoline. An additional advantage of the chemical recycling of carbon dioxide is that it uses undesirable carbon dioxide, which would otherwise be emitted into the atmosphere contributing to global warming.

SUMMARY OF THE INVENTION

The present invention discloses an efficient and economic way to overcome the previous difficulties encountered with bioethanol and to use the desirable compound methanol in a flex-fuel mixture with gasoline. This mixture comprises at least 10% gasoline, at least 10% bioethanol and at least 45% methanol, with the amount of gasoline, bioethanol and methanol totaling 100%. The flex-fuel mixture has an octane rating of at least 90 and remains homogeneous in the presence of up to 10% water therein.

In this flex-fuel mixture, both the gasoline and the bioethanol are each present in an amount of less than 33% of the mixture and the methanol is present in an amount of at least 50% of the mixture. Preferably, the methanol is present in an amount of less than 75% of the mixture. More preferably, the flex-fuel mixture comprises 10-15 to 30% gasoline, 50 to 75-80% methanol, and 10 to 25% of bioethanol and having an octane rating of 90 to 98.

The invention also relates to a method of making these flex-fuel mixtures by mixing the gasoline, bioethanol and methanol together in the amounts recited and under mixing conditions sufficient to form homogenous mixtures. The mixing may be conducted by first mixing the gasoline with the methanol to form a binary mixture and subsequently adding the bioethanol, or by first mixing the methanol with bioethanol to form a binary mixture and

subsequently adding the gasoline. Advantageously, the bioethanol is mixed with the gasoline and methanol without first having to be treated to remove associated water or without having to be rendered anhydrous. Also, the methanol can be made from carbon dioxide that is generated by an industrial plant to avoid emitting carbon dioxide into the atmosphere or from carbon dioxide that is removed from the atmosphere to reduce the contribution of the carbon dioxide to global warming.

The invention also relates to a method of storing, handling, transporting or dispensing a bioethanol containing fuel using existing infrastructure without the need to render and keep the fuel anhydrous which comprises formulating the fuel with at least 10% gasoline, at least 10% bioethanol and at least 45% methanol, with the amount of gasoline, bioethanol and methanol totaling 100%, wherein the flex-fuel mixture has an octane rating of at least 90 and remains homogeneous in the presence of up to 10% water therein.

Another embodiment of the invention relates to an improvement in a method for preparing a flex-fuel mixture of gasoline and bioethanol, wherein the improvement comprises adding methanol in an amount sufficient to enable the mixture to remain homogeneous in the presence of up to 10% water to thus allow handling, transportation, dispensing and use of the mixture in the same manner as conventional gasoline fuels without first having to treat the bioethanol to remove associated water or without having to be rendered anhydrous. Preferred flex-fuel mixtures of this method are those disclosed herein.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In this document, the term "bioethanol" is used to mean ethanol produced by fermenting various plant life, crops, or other cellulosic materials or natural products and is a renewable and environmentally friendly resource. The present invention discloses a feasible and more efficient new way to use bioethanol containing up to 10% water without expensive and costly dehydration or any special treatment to avoid moisture in transportation dispensing or use as a flex-fuel. It is based on producing and using ternary gasoline -methanol-bioethanol fuel mixture which are not phase separated in the indicated range. A typical gasoline-methanol binary fuel mix contains up to 85% methanol. This binary flex-fuel is completely miscible with bioethanol when the latter is added in amounts of 25% or less. Mixing with gasoline-methanol, there is no need for the bioethanol to be dry and can contain water (moisture) up to 10% making it practical for storage, transportation and use without any special treatment or facilities.

The disclosed ternary transportation fuel mixtures are easily accessible with the methanol produced by any known method, including the chemical hydrogenative recycling of carbon dioxide of industrial exhausts or natural sources as disclosed in US Patent Application 2006/0235091. The mixtures have the ability of being produced by recycling carbon dioxide through biological (i.e., photosynthetic and subsequent fermentative) ways as well as reductive chemical recycling of carbon dioxide allowing the carbon fuel mix to be used in an environmentally friendly way while also mitigating global warming.

The needed bioethanol can be produced from any suitable crops (sugar cane, corn, etc.), from cellulosic materials and other natural products. Their degradation/fermentation produce bioethanol. Nature's photosynthetic recycling of carbon dioxide to plant life together with the chemical recycling of carbon dioxide to methanol makes the disclosed gasoline - methanol-bioethanol ternary flex-fuel mix substantially carbon neutral.

A further advantage is the cleaner burning properties and high octane rating of the disclosed tertiary fuel mixes. Methanol has an octane number of -100 and bioethanol of 105. Thus, an octane rating of between 90 and 98 can be achieved by the formulation of the preferred amounts of the three components of the flex-fuel mixtures of the present invention. The high octane rating of these mixtures and their advantageous combustion properties are due to the beneficial effect of the oxygenates (i.e., the alcohols) that the mixtures contain and can be selected by skilled artisans as desired by the judicious selection of the amounts of the alcohols that are included in the mixtures. The optimum amounts can be determined by routine testing of the mixtures by starting with the preferred amounts disclosed herein.

The new ternary flex-fuels of the invention can be transported pre-mixed, stored and used without any specific precaution to exclude moisture or water condensation. These properties make the ternary fuel mix highly practical and economical. It eliminates the significant drawbacks of the use of bioethanol presently encountered in binary gasoline- ethanol mixtures. It allows the practical use of the ternary flex-fuel under usual conditions for storing, transporting, and dispensing transportation fuels through existing infrastructure used for gasoline. At the same time, the ternary fuel mix offers the advantages of high octane rating, good ignition and burning properties and complete miscibility without phase separation. The disclosed economical, convenient and highly efficient ternary fuel mix can be easy introduced and utilized with minimal additional cost of production, transportation and dispensing facilities and is adaptable with extremely limited minor changes of internal

combustion engine (ICE) vehicles. Thus, the flex-fuel mixtures of the invention can be handled, transported, dispensed and used in the same manner as conventional gasoline fuels.

The ternary flex-fuel mixtures described and claimed in present applications are conveniently prepared by mixing first methanol with gasoline in the indicated range of proportions and then admixing the appropriate amount of bioethanol without any dehydration of the azeotropic mixture, e.g., 96% ethanol-4% water obtained by distillation of any fermentation produced bioethanol. Alternatively, methanol and bioethanol can be premixed and thus gasoline added. There is no need to store, transport, dispense and use the ternary gasoline -methanol-bioethanol mixtures indicated within the range composition according to the claims under special conditions for excluding moisture to avoid water condensation. No phase separation of the flex-fuel mixture occurs and it burns efficiently in ICE vehicles with the aforementioned advantageous properties.