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Selecting a proper support in the catalyst system plays an important role in hydrogen production via ethanol steam reforming. In this study, sol gel made alumina supports prepared for nickel (Ni) catalysts were calcined at different temperatures. A series of (Ni/AlS.G.) catalysts were synthesized by an impregnation procedure. The influence of varying the calcination temperature of the sol gel made supports on catalyst activity was tested in ethanol reforming reaction. The characteristics of the sol gel alumina supports and Ni catalysts were affected by the calcination temperature of the supports. The structure of the sol gel made alumina supports was transformed in the order of γ → (γ + θ) → θ-alumina as the calcination temperature of the supports increased from 600 °C to 1000 °C. Both hydrogen yield and ethanol conversion presented a volcano-shaped behavior with maximum values of 4.3 mol/mol ethanol fed and 99.5%, respectively. The optimum values were exhibited over Ni/AlS.G800 (Ni catalyst supported on sol gel made alumina calcined at 800 °C). The high performance of the Ni/AlS.G800 catalyst may be attributed to the strong interaction of Ni species and sol gel made alumina which lead to high nickel dispersion and small particle size.

Computational fluid dynamics (CFD) modeling of spray dryers requires a simple but sufficiently realistic drying model. This work evaluates two such models that are currently in discussion; reaction engineering approach (REA) and characteristic drying curve (CDC). Two versions of the CDC, linear and convex, drop in drying rate were included. Simulation results were compared to the overall outlet conditions obtained from our pilot-scale experiments. The REA and CDC with a linear drop in drying rate predicted the outlet conditions reasonably well. This is contrary to the kinetics determined previously. Analysis shows that the models exhibit different responses to changes in the initial feed moisture content. Utilizing different models did not result in significantly different particle trajectories. This is due to the low relaxation time of the particles. Despite the slight differences in the drying curves, both models predicted similar particle rigidity depositing the wall. For the first time in a CFD simulation, the REA model was extended to calculate the particle surface moisture, which showed promising results for wet particles. Room for improvement was identified when applying this concept for relatively dry particles.

An examination of the aqueous solution solubility and batch crystallization kinetics of L-isoleucine at the 250 mL scale size under a poly-and isothermal process condition is presented. Solubility data determined are consistent with the existence of two L-isoleucine polymorphic forms, in which both forms have different solubility and they are enantiotropically related. These polymorphs (A and B) can be recovered at different cooling rates of cooling crystallization. Crystal characterization using optical microscopy, differential scanning calorimetry, X-ray powder diffraction, and Fourier transform IR microscopy confirm this polymorphic behavior. Polythermal crystallization kinetic studies revealed the crystallization temperature increases with cooling rate and solute concentration, which results in a decrease of the metastable zone width (MSZW) with a decreasing cooling/heating rate. The study also revealed that cooling rates affect the polymorph formation, where at cooling rates of 0.25-0.75 °C/min, form B is formed, while a more stable polymorph A can be recovered at a cooling rate of 0.10 °C/min. Isothermal studies showed that the range of nucleation rate is between 1.79 × 10 -5 and 7.53 × 10 -4 kg/(m 3 min), and the interfacial surface free energy at high and low supersaturation system is 1.74 and 0.576 mJ/m 2 , respectively. For a high supersaturation system, the critical cluster radius r* is between 5-17 Å, associated with between 3-121 molecules (N*), and for a low supersaturation system, r* is between 3 and 14 Å and N* is between 1 and 64. For a pH range of 5.1-6.3 and a temperature range between 10 and 80 °C, zwitterion species of L-isoleucine has remained as a dominating species in both solubility and crystallization studies. Thermodynamics properties generated from solubility data were also presented and discussed.