A spraying method for coating stainless steel surfaces with a commercial methanol synthesis catalyst was studied for the purpose of making a thin, active, and durable plate catalyst. The catalyst slurry was composed of CuO/ZnO/Al2O3/V2O3 powder dispersed in 2-propanol and was sprayed on a curved stainless steel surface. The coating was found to exhibit good adhesion to themetal surface and to provide a considerable increase in surface area relative to the geometrical area of the metal support surface (up to a factor of 11000). The effects of key method parameters, namely, the size of the catalyst particles in the suspension and the coating thickness, on the efficiency of coating and the morphology and durability of the coating were briefly investigated.
COBISS.SI-ID: 4899866
In a cooperation with pharmaceutical company a systematic study was carried out on the selection of optimal sovents and conditions to isolate active ingredients lovastatin from the fermentation broth, present in two forms, lovastatin acid and lovastatin lactone. The objective of the work was the determination of the partitioning of lovastatin to organic solvents, the effect of the contact time, the influence of pH and temperature on partitioning. Different affinities of solvents to both solutes were discussed and optimal operating conditions were recommended. Phase equilibria of a more-component system was modeled and a countercurrent extraction process was simulated to demonstate the applicability of the model to meet the separation requirements.
COBISS.SI-ID: 5003290
Isolation step of vancomycin, a glycopeptide antibiotic, is usually done from fermentation broth filtrate, while its adsorption directly from the whole broth could rationalize the process. The equilibrium and kinetics of vancomycin adsorption from broth supernatant, diluted and whole broth on polymeric adsorbent was studied in this work. Experimental equilibrium data was correlated with Sips, Langmuir, Freundlich, and linear adsorption isotherms. Agreement between measured and regressed data for the first three mentioned models did not vary much and was relatively high. The maximum adsorbed amount for supernatant was higher than for fermentation broths because mycelium particles blocked adsorbent surface. Liquid film mass transfer studies showed that external mass transfer resistance could have been neglected. Diffusion of vancomycin inside adsorbent particles was acknowledged using a nonstructural, homogenous surface diffusion and bidisperse pore models. Model simulations indicated that kinetics of the process could be improved by using smaller adsorbent particles.
COBISS.SI-ID: 34832133
A series of Pt-skin type catalysts has been synthesized in order to substantially enhance their specific and mass activity in MOR and ORR, two reactions known to have high activation polarization. Due to strain and ligand effects the Pt-skin catalysts shift the ORR potential to higher values by 50 mV. Adding Ru to the most active PtCu/C ORR catalyst creates a wider potential window in which MOR has a five-fold current density with respect to commercial PtRu (1:1)/C catalyst
COBISS.SI-ID: 5034266
The electrochemical degradation of PtNi and PtCu alloy nanoparticles is studied with a new, nondestructive variant of scanning electron microscopy (SEM). The method allows for observation of the same site (same nanoparticle) before and after electrochemical treatment, hence the name identical location SEM, IL-SEM. The method was complemented with other techniques such as energy-dispersive X-ray spectroscopy (EDS) and electrochemical thin film rotating disk electrode (TF-RDE) measurements. During initial potential cycling, the combined results show Ni or Cu dissolution and an increase in the electrochemical surface area (ESA). After accelerated degradation test (ADT), however, morphological changes (visible roughening) of the catalyst surface and a decrease in oxygen reduction reaction (ORR) specific activity are observed. In contrast to transmission electron microscopy (TEM and IL-TEM), the major advantage of SEM and IL-SEM is the ability to study surface phenomena rather than the bulk characteristic of a nano-object.
COBISS.SI-ID: 5094682