Tselishchev O. Scientific fundamentals of methods for the conversion of n-alkanes to high-octane motor fuel components

Doctors Thesis in Engineering Sciences. 05.17.07 – Chemical Technology of Fuels and Lub-ricants. – National Aviation University, Kyiv, 2019. The thesis is devoted to the study of technological aspects and principles of transformation n-alkanes into high-octane components of motor fuels that are based on the interaction of n-alkanes with hydroxyl radical. Hydroxyl radical has been proved to be the most effective alkanes activator (activation energy is the order of Ea = 8 kJ/mol) and play a key role in the oxidation of molecular nitrogen to nitrous oxide by the quantum-chemical calculations. The methods of hydroxyl radicals generators industrial realization for the technology of the direct alkanes conversion into methanol in the «soft» conditions on the basis of nitric acid vapor photo decomposition (λ ~ 330 nm ) and photochemical interaction of nitrogen dioxide with water molecule (λ ~ 420 nm), for the technology of improving motor fuel quality-based on the hydrogen peroxide dynamic cavitation, for the technology of molecular nitrogen oxidation – thermal decomposition of hydrogen peroxide (T ~ 773 К). Reaction apparatuses designs have been developed. The flow charts implementing proposed technological processes have been proposed. The technology of direct cavitation conversion of hydrocarbons to high-octane motor fuel components, for example to methanol, based on the cavitation of an aqueous solution of hydrogen peroxide, is experimentally investigated. It is established that cavitation in a stream of hydrogen peroxide solution begins at a velocity flow of more than 140 m/s; in the absence of hydrogen peroxide in the cavitation stream, the degree of conversion of natural gas and propane-butane gas to methanol is practically zero. For the process of direct cavitation conversion of natural gas to methanol and propane-butane gas to methanol, the optimal parameters that provide a ~ 10 % degree of conversion, are the following: the consumption ratio gas-hydrogen peroxide solution is 1:1, concentration of hydrogen peroxide in aqueous solution is 10–20 %, pressure in front of the nozzle – 19 MPa. During cavitation treatment of gasoline without hydrogen peroxide, there are processes of isomerization of n-alkanes and formation of toluene, which allows for an increase of octane number of gasoline by ~ 4 units. During cavitation treatment of gasoline with hydrogen peroxide there are processes of paraffine isomerization and formation of toluene and oxygenates, namely methanol, which allows for an increase of octane number of gasoline by ~ 10–12 units. Optimum parameters of gasoline cavitation treatment, which provide octane number increase by ~ 10–12 units, are the following: the consumption ratio gasoline-hydrogen peroxide solution is 10:1, concentration of hydrogen peroxide in aqueous solution is 10–20 %, pressure in front of the nozzle – 19 MPa. Process plant for cavitation conversion of hydrocarbons to high -octane motor fuel components is characterized by ~ 10 % degree of conversion, small number of vessels, low materials and metal consumption.