Towards sustainable industries: synthesis of alternative fuels and chemicals from fermentation products and integration of refineries and petrochemicals

• Autores: Elham Ketabchi
• Directores de la Tesis: Harvey Arellano-García (dir. tes.), Tomás Ramirez Reina (dir. tes.)
• Lectura: En la University of Surrey ( Reino Unido ) en 2020
• Idioma: inglés
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• Resumen

  • This thesis presents techniques from different angles with the objective of targeting the transition towards sustainable chemical industries with minimised greenhouse gas emissions. Oil refineries are selected as a representative example of heavy carbon industries. The shutdown and decreased efficiency of oil refineries are tackled in the first section of this work through connecting that plant to a compatible one, an ethylene production plant. This presents not only enhanced operational efficiency for the oil refinery, but the ethylene production also benefits through the use of oil refinery streams that are more of use in the second plant. Through this connection, the dependency on external feed purchase was decreased leading to less dependence on crude oil, making these industries evolve in the path of sustainability. Through mass balancing and stream exchange between the two plants, a substantial profit increase is achieved for both parties using data from a typical oil refinery and ethylene plant in the UK for increased applicability.

    In the same line as stepping towards less fossil fuel dependence and moving towards greener solutions, an alternative for producing chemicals and/or fuel from a “green” source, biomass, is investigated with the incentive of using economically viable catalysts of Ni, Fe and Cu on MgO-Al2O3 in addition to the developing of modern bio-refineries. Using Acetone, Butanol and Ethanol as reactants which are derived from sugar fermentation, they are upgraded to long-chain organic compounds at high temperatures and pressures. Through this experimental work, outstanding conversions and selectivities were achieved compared to available research whilst also maintaining practicality since the heavy burden of expenses has been relieved. The favourability of this process is also proven through calculations showing that the amount of CO2 emissions is reduced when using this process compared to conventional fossil-fuel-based ones. This is then followed by a systematic parametric study in order to optimise the reaction conditions while also understanding the effect of each parameter on the products attained. High temperatures and catalyst loadings have proven to demonstrate the best conversions and yielding of the products. Various reactant ratios are also tested, showing the significant role of butanol in the system. This study is also conducted with the aim of saving costs, energy and material to maintain the goal of sustainability and higher profit margins when practical.

    Lastly, after the identification of the complex reaction network occurring, calculations via the initial rate method are carried out to determine the kinetic values of the reactions. Using this, a preliminary kinetic model using mass balancing is produced. The apparent reaction rates obtained define the slowest and fastest reactions which are successfully in line with the experimental results. These values are then used to simulate the model and optimise them for increased accuracy. Comparing the modelled and experimental values, points of strength and weakness of the model are identified, providing a novel basis for implementing this process either in industrial scales or to incorporate this into process integration with a fossil-fuel based plant stepping towards hybrid refineries.

    Overall, this PhD work comprises modelling and experimental approaches to pursue sustainable processes and catalytic technologies aiming to develop a low-carbon chemical industry. The underlying concepts of hybrid and bio-refineries and CO2 emissions reduction for chemicals production have been the core motivation of this work whose original contributions have resulted in several peer-reviewed publications and one patent application.