How to Make a Cocktail of Palladium Catalysts with Cola and Alcohol: Heteroatom Doping vs. Nanoscale Morphology of Carbon Supports

Sparkling drinks such as cola can be considered an affordable and inexpensive starting material consisting of carbohydrates and sulfur- and nitrogen-containing organic substances in phosphoric acid, which makes them an excellent precursor for the production of heteroatom-doped carbon materials. In this study, heteroatom-doped carbon materials were successfully prepared in a quick and simple manner using direct carbonization of regular cola and diet cola. The low content of carbon in diet cola allowed reaching a higher level of phosphorus in the prepared carbon material, as well as obtaining additional doping with nitrogen and sulfur due to the presence of sweeteners and caffeine. Effects of carbon support doping with phosphorus, nitrogen and sulfur, as well as of changes in textural properties by ball milling, on the catalytic activity of palladium catalysts were investigated in the Suzuki–Miyaura and Mizoroki–Heck reactions. Contributions of the heteroatom doping and specific surface area of the carbon supports to the increased activity of supported catalysts were discussed. Additionally, the possibility of these reactions to proceed in 40% potable ethanol was studied. Moreover, transformation of various palladium particles (complexes and nanoparticles) in the reaction medium was detected by mass spectrometry and transmission electron microscopy, which evidenced the formation of a cocktail of catalysts in a commercial 40% ethanol/water solution

Improvement of quality of 3D printed objects by elimination of microscopic structural defects in fused deposition modeling

<div><p>Additive manufacturing with fused deposition modeling (FDM) is currently optimized for a wide range of research and commercial applications. The major disadvantage of FDM-created products is their low quality and structural defects (porosity), which impose an obstacle to utilizing them in functional prototyping and direct digital manufacturing of objects intended to contact with gases and liquids. This article describes a simple and efficient approach for assessing the quality of 3D printed objects. Using this approach it was shown that the wall permeability of a printed object depends on its geometric shape and is gradually reduced in a following series: cylinder > cube > pyramid > sphere > cone. Filament feed rate, wall geometry and G-code-defined wall structure were found as primary parameters that influence the quality of 3D-printed products. Optimization of these parameters led to an overall increase in quality and improvement of sealing properties. It was demonstrated that high quality of 3D printed objects can be achieved using routinely available printers and standard filaments.</p></div

Protons in the molecules of reagents and products for conversion calculation by NMR study.

<p>Protons in the molecules of reagents and products for conversion calculation by NMR study.</p

Printed cylindrical tubes of different wall thickness (l, mm).

<p>For each l value the corresponding wall structure and printing quality are displayed (all items were printed at k = 0.98).</p

Operational reliability of 3D printed polypropylene tubes.

<p>PP tubes as chemical reaction vessels in comparison with conventional glass test tubes. Values of k are given below for each 3D-printed tube. Performance in the studied chemical transformation is illustrated by product yield (in %) in each studied case, where ≥ 90% efficiency corresponds to excellent performance.</p

Objects of various shapes made of PLA by 3D printing.

<p>(A) cylinder, (B) cone, (C) sphere, (D) joined cylinder/cone, (E) pyramid, (F) cube.</p

Experimental demonstration of sealing properties of 3D-printed tube at different k-values.

<p>(A-F)–Evaluation of the of the number of pores in the wall of the tubes manufactured at different k-values; (G-I)–schematic representation of the effect of k-value on the porosity; (J, K)–electron microscopy image of the outer surface of an object printed at k = 0.85 showing a perforating pore (K); (L, M)—electron microscopy image of the outer surface of an object printed at k = 0.98 showing a smaller pore filled with polymer (M).</p

Evaluation of quality of 3D-printed shapes.

<p>(A) cylindrical test tube, (B) hollow entity of cubical shape, (C) spherical flask. In the top view, arrows indicate outgassing.</p

Heck reaction.

<p>Heck reaction.</p