scholarly journals Isokinetic parameters of thermal degradation of powder of [Cd(N-Boc-gly)2(H2O)2]n

2014 ◽  
Vol 46 (3) ◽  
pp. 323-330
Author(s):  
N. Begovic ◽  
M.M. Vasic ◽  
A. Grkovic ◽  
V.A. Blagojevic ◽  
D.M. Minic
Keyword(s):  
Coordination Polymer ◽  
Thermal Degradation ◽  
Compensation Effect ◽  
Covalent Bond ◽  
Isoconversional Methods ◽  
Coordination Bond ◽  
Kinetic Compensation Effect ◽  
Thermally Induced ◽  
Degradation Processes ◽  
Ligand Coordination

The coordination polymer [Cd(N-Boc-gly)2(H2O)2]n undergoes thermally induced degradation in temperature region between 60 and 900oC. Kinetic parameters were determined for dehydration (63-123oC) and further degradation processes (123-461?C) using different isoconversional and non-isoconversional methods. Due to appearance of kinetic ?compensation effect?, isokinetic temperatures were determined for individual degradation processes and correlated with resonant vibrational frequencies ascribed to Cd-OH2 coordination bond, Cd-O (O from N-Boc-glyH ligand) coordination bond and C-O covalent bond.

scholarly journals Kinetic compensation effect of isoconversional methods

2020 ◽  
Author(s):  
Andrzej Mianowski ◽  
Tomasz Radko ◽  
Tomasz Siudyga
Keyword(s):  
Heating Rate ◽  
Compensation Effect ◽  
Isoconversional Methods ◽  
Conversion Degree ◽  
Process Conditions ◽  
Activation Process ◽  
Isokinetic Temperature ◽  
Arrhenius Law ◽  
Kinetic Compensation Effect ◽  
Exponential Factor

AbstractFor experimental data obtained under different reaction/process conditions over time or temperature, the kinetic compensation effect (KCE) can be expected. Under dynamic (nonisothermal) conditions, at least two analytical pathways forming the KCE were found. Constant heating rate (q = const) and variable conversion degrees (α = var) lead to a vertical source of the KCE, called the isochronal effect. In turn, for a variable heating rate (q = var) and constant conversion degree (α = const), we can obtain an isoconversional compensation effect. In isothermal conditions (analyzed as polyisothermal), the KCE appears only as an isoconversional source of the compensating effect. The scattering of values for the determined isokinetic temperatures is evidence of a strong influence of the experimental conditions and the calculation methodology. The parameters of the Arrhenius law have been shown to allow the determination of the KCE and further the isokinetic temperature. In turn, using the Eyring equations for the same parameters, we can determine the enthalpy–entropy compensation (EEC) for the activation process and the compensation temperature, which is often treated as an isokinetic temperature. KCE effects have also been shown to be able to be amplified or dissipated, but isokinetic temperature is not a compensating quantity in the literal sense in isoconversional methods because $${T}_{iso}\to \infty .$$ T iso → ∞ . Thus, in isoconversional methods, isoconversional KCE values are characterized by strong variability of activation energy corresponding to the weak variation of the pre-exponential factor, which in practice means that $${\text{ln}}\mathit {A}\to {\text{const}}.$$ ln A → const . This is completely in line with the classical Arrhenius law.

Synthesis and Crystal Structure of the Flexible Ligand Coordination Polymer [Co3(bpd)5.5(NCS)6(NH3)]n⋅2H2O(bpd= 1,4-bis (4-pyridyl)-2,3-diaza-1,3-butadiene)

2013 ◽  
Vol 803 ◽  
pp. 80-84
Author(s):  
Yu Qi Liu ◽  
Yong Yang ◽  
Rui Yang ◽  
Xiao Jun Xu
Keyword(s):  
Crystal Structure ◽  
Infrared Spectroscopy ◽  
Coordination Polymer ◽  
Single Crystal ◽  
X Ray Diffraction ◽  
Synthesis And Crystal Structure ◽  
X Ray ◽  
Elemental Analyses ◽  
Ligand Coordination ◽  
Point Symbol

A novel metalorganic coordination polymer, namely [Co3(bpd)5.5(NCS)6(NH3)]n2H2O (1) (bpd=1,4-bis (4-pyridyl)-2,3-diaza-1,3-butadiene), has been synthesized and characterized by elemental analyses, infrared spectroscopy, and single-crystal X-ray diffraction. Compound 1 presents 2D[3,4,-connected 3-nodal net with the point symbol (4268210)(4462)(8210). In addition, four identical 2D single nets is interlocked with each other in parallel, thus directly leading to the formation of a polycatenated layer (2D2D).

scholarly journals Analysis on the MSW thermal degradation processes

2013 ◽  
Vol 9 (1) ◽  
pp. 57-62
Keyword(s):  
Thermal Degradation ◽  
Municipal Solid Waste ◽  
Solid Waste ◽  
Degradation Kinetics ◽  
Variable Temperature ◽  
Fixed Bed ◽  
Reduction Rate ◽  
Pollutant Emissions ◽  
Process Conditions ◽  
Degradation Processes

The waste to renewable energy source has become a priority in the wastes treatment field. The research goal is not only the wastes destruction but also a better thermal energy recovery from the processes. The municipal solid waste presents a high heterogeneity degree from the dimensional point of view, form and its components specific weight of as well as thermal-chemical characteristics. That’s why there are many treatment methods, each one with its own particularities. For a better understanding of the phenomenon during thermal degradation processes both under pyrolysis or atmospheric pressure gasification stages we first accomplished a laboratory scale series of experiments in a tubular reactor, on small quantities (5 – 10 grams) of reconstituted urban wastes. For the validation of the obtained data on more representative samples we extended the experiment to an original industrial scale pilot installation that enables the continuous thermal treatment of 10 – 50 waste kilograms per hour under oxidant or non-oxidant atmosphere (on choice) and at variable temperature between 400 °C – 1100 ºC. The residential time of the treated sample in the installation and the flow conditions can be set independently. The installation reproduces the incinerators or the pyrolysis / gasification reactor process conditions and provides complete information on the wastes thermal degradation kinetics and on the pollutant emissions. The particularity of the device consists in the product advancing piston – like flow system based on the bed vibration. The product particles in the bed have a translation movement without any layer shift. Therefore the particles distribution in a given product bed section is the same all along the installation from the feeding inlet to the extraction. That characteristic enables us to extrapolate and compare the laboratory results of the fixed bed treatment to the industrial pilot continuously treatment applied on the same product: reconstituted municipal solid waste, one of the most heterogynous solid wastes in mixture. The main targets were the sample mass reduction rate, the resulting gases composition, the samples mechanical behavior for different temperature levels, residential time, treatment atmosphere conditions and different steam flow rates (in the gasification process). The results were compared to an established reference – the incineration. The paper presents the research and results on the degradation mechanisms of MSW treated samples in those two equipments from the Science Division CNRS, Department of Industrial Methods, University of Technology Compiègne, France.

Synthesis, characterization and fluorescence properties of mixed-ligand cobalt(II), copper(II), zinc(II) and cadmium(II) coordination polymer complexes involving 4,4’-bipyridine and 2,5-pyridinedicarboxylic acid

2021 ◽  
Vol 25 (7) ◽  
pp. 147-156
Author(s):  
Ajeet Kumar Maurya ◽  
Ashish Kumar Srivastava ◽  
Krishna Srivastava ◽  
Jagdish Prasad
Keyword(s):  
Coordination Polymer ◽  
Thermal Analyses ◽  
Mixed Ligand ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Polymer Complexes ◽  
Pyridinedicarboxylic Acid ◽  
Elemental Analyses ◽  
Ligand Coordination ◽  
Ft Ir

Four mixed-ligand coordination polymer complexes of cobalt(II), copper(II), zinc(II), and cadmium(II) were synthesized by solvothermal method in 1:1:1 metal: 4,4’-bipy: 2,5-pdc molar ratio using 2,5-pyridinedicarboxylic acid (2,5-pdc) and 4,4’-bipyridine (4,4’-bipy). These complexes are viz; 1. [Co2(4,4'-bipy)(2,5-pdc)2(H2O)4]n 2. [Cu2(4,4'-bipy) (2,5-pdc)2]n 3. [Zn2(4,4'-bipy)(2,5-pdc)2(H2O)4]n and 4. [Cd3(4,4'-bipy)(2,5-pdc)2(OOCCH3)2(H2O)4]n.. All these complexes (1-4) have been characterized by elemental analyses (C,H,N), FT-IR-spectra, thermal analyses (TGA/DTA/DTG), fluorescence spectra and powder X-ray diffraction (PXRD) analyses to arrive at conclusion regarding their geometrical structure.

The Effect of Thermal Degradation Processes on the Physical-Mechanical and Rheological Properties of Polyketone

2020 ◽  
Vol 869 ◽  
pp. 140-145
Author(s):  
Vladimir N. Vodyakov ◽  
Alexandr V. Kotin ◽  
Vyacheslav V. Kuznetsov ◽  
Kseniya A. Kulikovskaya ◽  
Elena A. Radaykina ◽  
...  
Keyword(s):  
Thermal Degradation ◽  
Rheological Properties ◽  
Thermal Processing ◽  
Mechanical Characteristics ◽  
Compression Molding ◽  
Degradation Processes ◽  
Molding Methods ◽  
Physical And Mechanical Characteristics

The effect of polyketone thermal processing duration on the rheological properties of the melts and the physical and mechanical characteristics of the samples, obtained by injection and compression molding methods, is studied.

scholarly journals Kinetic Analysis of the Thermal Degradation of Recycled Acrylonitrile-Butadiene-Styrene by non-Isothermal Thermogravimetry

Polymers ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 281 ◽  
Author(s):  
Rafael Balart ◽  
David Garcia-Sanoguera ◽  
Luis Quiles-Carrillo ◽  
Nestor Montanes ◽  
Sergio Torres-Giner
Keyword(s):  
Thermal Degradation ◽  
Kinetic Analysis ◽  
Acrylonitrile Butadiene Styrene ◽  
Isoconversional Methods ◽  
Reaction Model ◽  
Integral Model ◽  
Heating Rates ◽  
Exponential Factor ◽  
Model Free ◽  
Butadiene Styrene

This work presents an in-depth kinetic study of the thermal degradation of recycled acrylonitrile-butadiene-styrene (ABS) polymer. Non-isothermal thermogravimetric analysis (TGA) data in nitrogen atmosphere at different heating rates comprised between 2 and 30 K min−1 were used to obtain the apparent activation energy (Ea) of the thermal degradation process of ABS by isoconversional (differential and integral) model-free methods. Among others, the differential Friedman method was used. Regarding integral methods, several methods with different approximations of the temperature integral were used, which gave different accuracies in Ea. In particular, the Flynn-Wall-Ozawa (FWO), the Kissinger-Akahira-Sunose (KAS), and the Starink methods were used. The results obtained by these methods were compared to the Kissinger method based on peak temperature (Tm) measurements at the maximum degradation rate. Combined Kinetic Analysis (CKA) was also carried out by using a modified expression derived from the general Sestak-Berggren equation with excellent results compared with the previous methods. Isoconversional methods revealed negligible variation of Ea with the conversion. Furthermore, the reaction model was assessed by calculating the characteristic and functions and comparing them with some master plots, resulting in a nth order reaction model with n = 1.4950, which allowed calculating the pre-exponential factor (A) of the Arrhenius constant. The results showed that Ea of the thermal degradation of ABS was 163.3 kJ mol−1, while ln A was 27.5410 (A in min−1). The predicted values obtained by integration of the general kinetic expression with the calculated kinetic triplet were in full agreement with the experimental data, thus giving evidence of the accuracy of the obtained kinetic parameters.

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