Kinetic non-reversibility of the cracking reactions and its accounting during mathematical modeling of industrial process

The paper presents the approach to the catalytic cracking modeling with consideration of the reactions' reversibility/non-reversibility depending on the current concentrations and the cracking temperature. The thermodynamic analysis of the reactions using the quantum-chemical methods allows formulating a hydrocarbons conversion scheme at the thermal equilibrium temperature between the feedstock and the catalyst. The magnitude of the current chemical attraction of reactions is a criterion of thermodynamic non-reversibility of reactions, which is determined at each stage of the calculation. It has been shown that the change in the concentrations of conversion participants and cracking temperature have a significant effect on the catalytic cracking reactions. Thus, the cyclization reactions are non-reversible up to 512.9 °C (A[rij]=6.46 kJ/mol) during the processing of feedstock with saturated hydrocarbons to aromatics ratio is 2.1 and with further temperature increasing the contribution of reverse reactions rises. Also with increasing the saturated hydrocarbons to aromatics ratio from 2.1 to 3.2 in the feedstock, the equilibrium of the reaction shifts to low temperatures from 512.9 to 508.9 °C (A[rij]=6.497 kJ/mol). It is connected with the fact that intensification of the exotermic reactions (alkylation, condensation, coke formation) under certain conditions is possible. It is an important factor in terms of catalyst deactivation and has an effect on the desired product yield

Multicomponent synthesis of propargylamines in the presence of magnetic nanocatalyst

880-885In current study Fe3O4 nanoparticles have been used as a catalyst in the synthesis of propargylamines via three component reaction between aldehyde, alkyne, and an amine. The effect of different reaction parameters on conversion of aldehyde has been investigated and the samples have been characterized by appropriate techniques. It has been observed that in the presence of Fe3O4 nanoparticles and by applying microwave irradiation reaction time decreased significantly

Micron-scale rod-like scattering particles for light trapping in nanostructured thin film solar cells

Spherical dielectric particles, nanofibers, and nanorods have been widely used as embedded scattering objects in nanostructured thin film solar cells. Here we propose micron-scale rod-like dielectric particles as a more effective alternative to the spherical ones for light trapping in thin film solar cells. The superior performance of these micro-rods is attributed to their larger scattering efficiency relative to the spherical particles as evidenced by full-wave optical calculations. Using a one-pot process, 1.7 mu m-long bullet-shaped silica rods with 330 nm diameter are synthesized and their concentration in a N719-sensitized solar cell is optimized. A solar cell with an optimal concentration of rod-like particles delivers 8.74% power conversion efficiency (PCE), given the 6.33% PCE of the cell without any scattering particle. Moreover, a silver layer is deposited by chemical reduction of AgNO3 (Tollens' process) on the rear-side of the counter electrode, and hence the PCE of the optimal cell reaches 9.94%, showing 14% extra improvement due to the presence of the silver back-reflector. The rod-like scattering particles introduced here can be applied to other sensitized solar cells such as quantum-dot and organometallic perovskite solar cells

One-pot and gram-scale synthesis of biodegradable polyglycerols under ambient conditions: nanocarriers for intradermal drug delivery

Hyperbranched polyglycerols (hPGs) have a variety of biomedical applications due to their unique physicochemical properties such as biocompatibility and multi-functionality. However, their lack of biodegradability under physiological conditions hampers their in vivo applications. Therefore, the development of straightforward methods for the synthesis of biodegradable hyperbranched polyglycerols is of great importance. In this work, caprolactone segments were incorporated into the backbone of polyglycerols by a one-pot, ring-opening copolymerization of glycidol and ε-caprolactone under ambient conditions. While the synthesized polyglycerols were susceptible to enzymatic cleavage, they were stable under neutral and acidic conditions. In spite of their high cellular uptake that was proven by laser scanning confocal microscopy (LSCM), the MTT assay did not show a significant toxicity against HaCaT cells up to 1000 μg ml(−1). The biodegradability and biocompatibility of the synthesized polymers together with their ability to form nanoparticles in aqueous solutions and loading of hydrophobic guest molecules encourage us to evaluate their application as intradermal delivery systems. Ex vivo skin penetration tests showed that the synthesized polymers enhanced the Nile red penetration into the skin upon enzymatic degradation. While polymers stayed at the superficial stratum corneum, the released cargo penetrated into the deeper layers of the skin

A One-Step Preparation of Tetradentate Ligands with Nitrogen and Phosphorus Donors by Reductive Amination and Representative Iron Complexes

This is the accepted article.The synthesis and use of the first examples of unsymmetrical, mixed phosphine donor tripodal NPP’2 ligands N(CH2CH2PR2)2(CH2CH2PPh2) are presented. The ligands are synthesized via a convenient, one pot reductive amination using 2-(diphenylphosphino)ethylamine and various substituted phosphonium dimers in order to introduce mixed phosphine donors substituted with P/P’ being Ph/Cy (2), Ph/iPr (3), Ph/iBu (4), Ph/o-Tol (5), and Ph/p-Tol (6). Additionally, we have developed the first known synthesis of a symmetrical tripodal NP3 ligand N(CH2CH2PiBu2)3 using bench safe ammonium acetate as the lone nitrogen source (7). This new protocol eliminates the use of extremely dangerous nitrogen mustard reagents typically required to synthesize NP3 ligands. Some of these tetradentate ligands and also P2NN’ ligands N(CH2-o-C5H4N)(CH2CH2PR2)2 (P2NN’-Cy, R = Cy; P2NN’-Ph, R = Ph) prepared by reductive amination using 2-picolylamine, are used in the synthesis and reactions of iron complexes. FeCl2(P2NN’-Cy) (8) undergoes single halide abstraction with NaBPh4 to give the trigonal bipyramidal complex [FeCl(P2NN’-Cy)][BPh4] (9). Upon exposure to CO(g), complex 9 readily coordinates CO giving [FeCl(P2NN’-Cy)(CO)][BPh4] (10) and further treatment with an excess of NaBH4 results in formation of the hydride complex [Fe(H)(P2NN’-Cy)(CO)][BPh4] (11). Our previously reported complex FeCl2(P2NN’-Ph) undergoes double halide abstraction with NaBPh4 in the presence of he coordinating solvent to give [Fe(NCMe)2(P2NN’-Ph)][BPh4]2 (12). Ligand 3 can be coordinated to FeCl2 and upon sequential halide abstraction, treatment with NaBH4, and exposure to an atmosphere of dinitrogen, the dinitrogen hydride complex [Fe(H)(NPP’2-iPr)(N2)][BPh4] (13) is isolated. Our symmetrical NP3 ligand 7 can also be coordinated to FeCl2 and upon exposure to an atmosphere of CO(g), selectively forms [FeCl(NP3)(CO)][BPh4] (14) after salt metathesis with NaBPh4. Complex 14 can be treated with an excess of NaBH4 to give the hydride complex [Fe(H)(NP3)(CO)][BPh4] (15) which can further be deprotonated/reduced to the Fe(0) complex Fe(NP3)(CO) (16) upon treatment with an excess of KH.NSERC is acknowledged for a Discovery Grant to R. H. M. and the Strategic Grant “Catalytic Synthesis of Specialty Chemicals from Sustainable Resources.” The Ontario Government is acknowledged for an Ontario Graduate Scholarship for M. V. G