Chemical Informatics

Description

The pyrolysis of low-rank coal is clearly catalyzed by the intrinsic alkali and alkaline earth metals (AAEMs).The catalytic effects of AAEMs with various occurrence states may differ due to differences in dispersion degree and chemical form. The most direct evidence for the catalysis of AAEMs is provided by the chemical structures of coal and charcoal. However, there has never been a solution to the problem of quantitatively characterizing and evaluating these structures, particularly the asymmetric functional groups. The functional group structures of these samples were semi-quantitatively characterized by a series of original infrared structural parameters, and the volatile products during pyrolysis were detected using TG-FTIR in this study. The FT-IR spectra of Zhundong coal and char containing various forms of intrinsic AAEMs were also fitted. The char's water-soluble and ion-exchangeable AAEMs, according to a comprehensive analysis of functional group structures, weight-loss rates, and volatile product concentrations, promote the thermal cracking of aromatic C–H groups while preventing the release or decomposition of –COO and aliphatic C–H groups. It is also confirmed that ion-exchangeable AAEMs inhibit the release and decomposition of Ar–O groups as well as the dehydrogenation and polycondensation of aromatic clusters in char. The infrared structural parameter method that is being proposed in this paper is expected to be a reasonable, efficient, all-encompassing, and universal method for quantitatively defining the functional group structures of coal and char. It will also improve the current system of coal quality analysis and provide a new tool for evaluating and communicating the chemical structures of coal and char.

Chemical and Structural Changes That Occurred In Coking Coals

After the plastic layers have re solidified during the cooking process, the carbon structure of coal changes to form a solid residue known as semi-coke. This solid residue is what determines the structure and quality of the final coke product. This paper discusses the chemical and structural changes that occurred in Australian coking coals at the end of the plastic layer stage, which may have something to do with how carbon structures changed. In a lab-scale coke oven, the plastic layers and semi-coke/coke samples were made from four Australian coking coals of varying ranks and vitrinite contents. A combination of X-ray photoelectron spectroscopy and Synchrotron attenuated total reflection Fourier transform infrared micro spectroscopy was used to examine the changes in the chemical structure that occur during the formation of coke. As a nondestructive analytical method, Synchrotron IR proved to be useful for examining the shift in functional groups in the semi-coke samples. The conversion of sp2- and sp3-bonded carbons was investigated with the help of the XPS analysis. The findings suggested that from the plastic layers to the coke/semi-coke regions, a significant shift in chemical structure occurred. The characteristics of the parent coals had a significant impact on the changes in chemical structure. The ratio of out-of-plane aromatic Csingle bondH to Cdouble bondC bonds in aromatic rings was used to determine the degree of aromatic ring condensation, and the changes in carbon structure that were observed in XPS spectra were in good agreement with these changes. The findings demonstrated that the semi-coke was formed as a result of the evolution of the carbon structure during the later thermoplastic ranges. It seems obvious that changes in conditions during the synthesis of polyols have an effect on the properties of polyols. Even though the chemical formula is the same or similar, the physicochemical properties and molecular weight of polyols may differ, which will have a significant impact on the properties and processing of future polyurethanes. In this study, thermoplastic polyurethane elastomers were made using fully bio-based poly (propylene succinate)s that were made at various temperatures as a polyol. The previously mentioned bio-based linear polyester polyols, poly (propylene succinate)s as well as 4,4-diphenylmethane diisocyanate and a natural chain extender, either 1,4-butanediol (BDO) or 1,3-propanediol were used to create novel bio-based TPUs. Investigating the chemical structure, thermal, thermo mechanical, mechanical, and physical properties of synthesized bio-based TPU allowed for the determination of the influence of synthesized bio-based polyols on the characteristic of thermoplastic polyurethane elastomers. The chemical formula was determined using Fourier Transform Infrared Spectroscopy (FTIR) and proton nuclear magnetic resonance (1H NMR). Thermogravimetry helped with thermal analysis, and the tensile test, hardness, and Dynamic Mechanical Analysis (DMA) were used to find thermo mechanical behavior and mechanical properties in static and dynamic conditions. Additionally, the obtained materials' density was measured. It was established that thermoplastic polyurethane elastomers can be synthesized without the use of catalysts with fully bio-based polyester polyols. The results showed that the type of chain extender had a greater impact on the properties of bio-based TPU than the condition of bio-based polyester synthesis. Glass temperature was used to classify each sample.0 to 5 °C and similar thermal stability approximately320°C. Prepared bio-based TPUs have an elongation at break ca. of 30 MPa and their tensile strength even exceeds 30 MPa. 550%.

Conversion of Functional Groups Varied

Cement hydration, early-age autogenous shrinkage, and the mechanical properties of cement paste are the subjects of this investigation into the absorption behavior of superabsorbent polymer with various chemical structures. Because the anionic groups on the SAP network complexed with multivalent cations in the pore solution SAP with a high density of anionic functional groups quickly absorbed and released the cement pore solution. SAP had a much lower measured release because of its low anionic group density. Additionally, the liquid did not escape from SAP with only non-ionic groups or with both cationic and anionic groups. All SAP was able to combat autogenous shrinkage, despite their distinct solution behavior. Internal curing was excellent in SAP with either both ionic groups and a high density of anionic groups. When the total cement-to-water ratio was taken into consideration, the internal curing did not have any negative effects on the paste's compressive strength. At various pyrolysis temperatures, the influence of pressure on the conversion of functional groups varied. Under 1 MPa, the pressure had distinct effects on the structure of coal char's carbon skeleton and primarily encouraged the graphitization of samples during pyrolysis. In addition, elevated pressure had no effect on the ratios of phenolic hydroxyl, ether, or aliphatic aromatic in char.