Mixing-assisted oxidative desulfurization of diesel fuel using quaternary ammonium salt and portable unit thereof

Abstract

The desulfurization of fossil fuels is provided by the combination of fossil fuels with an aqueous mixture of ozone or hydrogen peroxide and a Tetraoctylphosphonium salt phase transfer catalyst, and the mixture is then subjected to reactive mixing to form oxidize sulfur compounds in the fuel. The polar oxidized sulfones species are removed via another mixing step. The desulfurization device can be in the form of a portable device which provides for continuous mixing-assisted desulfurization for the removal of sulfur containing compounds from fossil fuels such as diesel fuel.

Description

BACKGROUND[0001]1. Field of the Invention[0002]This disclosure resides in the field of the desulfurization of petroleum, fossel fuel, and / or petroleum-based fuels.[0003]2. Description of the Related Art[0004]Diesel fuel is one of the more commonly-used fossel fuels today in transportation. Because it is widely known that diesel engines are inherently more thermally and energy efficient than gasoline engines, it is expected that the demand for diesel fuel will likely increase more and more in the future due to higher global environmental consciousness as well as the green movement as was seen happening in recent years. Diesel fuels are generally relatively complex mixtures of alkanes, cycloalkanes, and aromatic hydrocarbons with carbon numbers in the range of C9-C28 and with a boiling-range of 150-390 degrees C. Their relative distribution depends on the specific fuel feedstock, refining process, and actual blending schemes based on day-to-day commercial demands of the end user. Two ...

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Benefits of technology

[0011]In order to overcome the above mentioned problems, one aspect of this disclosure is directed to a method of mixing-assisted oxidative desulfurization (MAOD) of fossil fuels in which the fossil fuel is combined with an aqueous oxidizer solution including hydrogen peroxide or ozone solution containing a quaternary ammonium salt having at least one carbon chain of 8 or more carbon atoms as a phase transfer catalyst to achieve improved conversion of sulfides to sulfoxides with higher yield and without the unwanted formation of brominated side products.

[0012]In another aspect of this disclosure is directed to a method of mixing-assisted oxidative desulfurization of fossil fuels in which the fossil fuel is combined with an aqueous hydrogen peroxide solution or ozone solution containing a quaternary ammonium salt as a phase transfer catalyst to achieve improved conversion of sulfides to sulfoxides as contained in the organic phase fuel using a plurality of mixing tanks and a plurality of cyclones, without having to require the use of any sonoreactor or ultrasonic device, which can be complex, unreliable, and expensive. In addition, by not using any sonoreactor, there would be no need for cooling the multiphase reaction medium by thermal contact with a coolant medium during the oxidative desulfurization of fossil fuels process using the mixing tank / cyclone system, as well as requiring much less energy consumption during desulfurization. The mixing-assisted oxidative desulfurization process of this disclosure is also advantageous over the conventional sonoreactor or ultrasonic desulfurization process, for example, with respect to having much fewer problems relating to scale up to mass production because of the lack of the accompanying corresponding function generator and RF amplifier that are found in sonoreactors, and not presenting long term detriment to possible chain cracking of long chain hydrocarbons.

Problems solved by technology

Upon combustion, the sulfur leads directly to the emission of SO2 and sulfate particulate matter, which are serious health hazards and can easily endanger public health.

Moreover, the sulfur can also lead to other problems such as poisoning of the catalytic converters, corrosion of parts of internal combustion engines, and increased air pollution.

However, even small amounts of unreacted hydrogen sulfide from the desulfurization process can be harmful.

Hydrogen sulfide has an extremely high acute toxicity, which has caused many deaths in the workplace, and is thus hazardous to workers.

One of the difficulties with the newer EPA regulations on reducing sulfur contents is that when the hydrodesulfurization is performed under these more stringent conditions, there would be an increased risk of hydrogen leakage through the walls of the reactor.

Moreover, the sonoreactor utilized in the desulfurization process also possesses many disadvantages such as, for example, requiring very expensive equipments which also requires technical sophisticated parts such as an RF amplifier and a function generator, requiring higher electrical power consumption due to the generation of ultrasonic fields, requiring to operate at higher operating temperatures, typical at between 70 to 80° C., and the ultrasound potentially present long term detriment to possible chain cracking of long chain hydrocarbons.

Moreover, the conventional sonoreactor or ultrasonic desulfurization equipment possess practical limitations with respect to scale up to mass production because of also the need to scale up of the corresponding function generator and RF amplifier.

Therefore, such reactions are typically slow, taking hours, and the product has to be isolated at the end of the process cycle.

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