Taddeo, Francesco (2022) New green solvents and additives for the industry of printing inks. [Tesi di dottorato]

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Abstract

Biomass represents an extremely important alternative to the conventional raw materials derived from fossil resources. The growing attention towards environmental safety has led to the development of new processes starting from renewable resources. The present thesis is devoted to the use of two different chemicals, pelargonic acid and levulinic acid, commercially available that can be obtained from biomass. In particular, this thesis can be theoretically divided into three main parts. The first part is focused on the esterification reaction of pelargonic acid with 2-ethylhexanol. A batch and continuous kinetic study were performed in the presence of both homogeneous (sulfuric acid) and heterogenous catalysts. As for the heterogenous catalysts, different types were tested: among these Amberlyst15 and Amberlite IR120 were tested both in batch and in continuous apparatus while a synthetic catalyst (H2WO4/SiO2) was tested in batch reactor. In the case of the batch kinetic investigation different experimental conditions (stirring rate,temperature, reactants molar ratio and catalyst load) were varied in order to determine the kinetic and thermodynamic parameters. As for the continuous kinetic study, instead, temperature, reactants molar ratio and volumetric flowrate were varied. It was demonstrated that for the considered heterogeneous catalysts, an internal mass transfer limitation occurred. A kinetic model was elaborated obtaining a good agreement between the experimental data and the simulated curves. Overall, Amberlyst-15 showed a better behavior compared to Amberlite IR120 due to the different structure of the resins themselves and a more accessible pores in the case of Amberlyst-15 leading to a lower intraparticle mass transfer limitation. The second part of the present thesis was focused on the synthesis of solvents to use in the formulation of printing inks through an esterification reaction of the pelargonic acid itself with 2-ethylhexanol. In this case, a different reactor configuration was considered consisting in a loop reactor and for this purpose, Amberlyst-15 was chosen as heterogenous catalyst. The solvents synthesized in all these experiments were tested in formulations for printing inks investigating their characteristics and evaluating the rheological properties of the derived inks. The obtained results confirmed the excellent properties of these solvents compared to what is reported in the literature. The third part of the thesis was devoted on the ketalization reaction: this part started with the batch kinetic study of the ketalization of acetone and glycerol and after that the attention was focused on ethyl levulinate ketalization with glycerol. Firstly, a catalytic screening was made to investigate the best catalysts for this reaction. Among these, different types of zeolites, ion exchange resins and a synthetic catalyst were tested. The most promising resulted to be Dowex 50WX8 among the ion-exchange resins and Y zeolite and beta zeolite. Based on these results, Y-zeolite was firstly chosen to perform a kinetic study and several tests were performed in different experimental conditions in order to evaluate their effect on the reaction rate and determine thermodynamic and kinetic parameters.

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