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The study and the understanding of the importance of the morphological properties of heterogeneous catalysts can pave the way for important improvements in the performance of catalytic systems. Non-uniform active phase distribution catalysts are normally adopted for consecutive reactions to improve the selectivity to the desired intermediate product. Attributes on which minor attention is paid, such as the distribution and thickness of the active phase, can be decisive in the final rationale of the catalyst synthesis strategy. Starting from a previous work, where a single non-uniform active phase model for catalyst particles was developed, a key step to control the entire system is to include the bulk-phase equations and related transport phenomena. For this purpose, this work proposes a modeling approach of a biphasic reactive system in a batch reactor in the presence of three different kinds of catalytic particles (egg shell, egg white, and egg yolk) whose distinction lies in the localization of the active zone. The reactive network consists of a couple of reactions in series, which take place exclusively on the solid surface, and the intermediate component is the main product of interest. To reveal the influence related to the type of catalyst, an extensive parametric study was conducted, varying several structural coefficients to highlight the changes in the intraparticle and bulk concentration profiles of the different chemical species. The main results can be considered of wide interest for the chemical reaction engineering community, as it was demonstrated that mass and heat transfer limitations affect the catalyst performance. For the chosen system, the egg shell catalyst normally led to better catalytic performances.

To maximize the performances of heterogeneous catalytic reactors, it is necessary to consider many parameters. Catalytic particle morphology (dimension, shape, active phase distribution) is generally previously established and seldom considered in the optimization of the catalyst to be specific for a given process. In this work, the influence of active phase distribution within spherical catalytic particles (egg-shell, egg-yolk and egg-white), on the yield and selectivity of a product is shown for a consecutive reaction network, here, the intermediate component is the main product of interest. Intraparticle mass and energy balances under non-steady conditions were implemented. Sensitivity studies lead to the identification of the optimal conditions, thus maximizing the yield of the intermediate for each active phase distribution. It was demonstrated that the egg-shell catalyst can maximize the intermediate yield, with a lower active-phase usage.

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In this work, biodegradable films based on poly (lactic acid) (PLA) and corn thermoplastic starch (TPS), additivated with epoxidized cardoon oil plasticizer (ECO) at 3% by weight with respect to PLA mass fraction, were prepared by melt extrusion process and compression molding. The effect of ECO on structural, thermal, mechanical, barrier, and spectral optical properties of the films was investigated. Spectroscopic analysis evidenced the development of physical interaction between oil and polymers, mainly PLA. In addition, no oil migration occurrence was detected after six months of film preparation, as evidenced by oil mass evaluation by precipitation as well as by 1H-NMR methods, thus highlighting the good inclusion of oil inside the polymeric network. The plasticizing action of the oil induced a lean improvement of the interfacial adhesion between hydrophobic PLA and hydrophilic TPS, particularly accentuated in PLA80_ECO composition, as evidenced by morphological analysis of blend fracture surfaces. TGA data underlined that, differently from TPS-based films, PLA-based systems followed one degradative thermal profile suggesting a slight compatibilization effect of epoxidized oil in these films. The shifting of Tg values, by differential scanning calorimetry (DSC) analysis, indicated a weak miscibility at molecular level. Generally, in the investigated blends, the phase separation between PLA and TPS polymers was responsible for the mechanical properties failing, in particular, the tensile strength evidenced a negative deviation from the rule of mixtures, particularly marked in TPS-based blends, where no physical entanglements occurred between the polymers since their immiscibility even in presence of ECO. The epoxidized oil strongly improved the barrier properties (water vapor permeability (WVP) and oxygen permeability (O2P)) of all the films, likely developing a physical barrier to water and oxygen diffusion and solubilization. With respect to neat PLA, PL80 and PL80_ECO films evidenced the improvement of surface wettability, due to the presence of polar groups both in TPS (hydroxyl residues) and in epoxidized oil (oxirane rings). Finally, following to the conditioning in climatic chamber at T = 25 &deg, C and RH = 50%, PLA80 film became opaque due to TPS water absorption, causing a light transmittance decreasing, as evidenced by spectral optical analysis.