Classification of Fuel Blends Using Exploratory Analysis with Combined Data from Infrared Spectroscopy and Stable Isotope Analysis

Chemometric tools were applied for exploratory analysis and classification of fuel blends using the combined information on Fourier transform infrared spectroscopy and stable isotope analysis through isotope ratio mass spectrometry. Principal component analysisand hierarchical clustering analysis were applied for exploratory analysis, while support vector machine (SVM) was used to classify the biodiesel/diesel blends. All of the chemometric models used present better results from the combination of spectral information with isotopic data for biodiesel contents of over 10% in the mixture, with the best results being obtained from the SVM classification. Therefore, the development presented in this paper could become an important technique to improve the discrimination of the feedstock used in biodiesel production and a resource for quality control in industry

Classification of Fuel Blends Using Exploratory Analysis with Combined Data from Infrared Spectroscopy and Stable Isotope Analysis

Chemometric tools were applied for exploratory analysis and classification of fuel blends using the combined information on Fourier transform infrared spectroscopy and stable isotope analysis through isotope ratio mass spectrometry. Principal component analysisand hierarchical clustering analysis were applied for exploratory analysis, while support vector machine (SVM) was used to classify the biodiesel/diesel blends. All of the chemometric models used present better results from the combination of spectral information with isotopic data for biodiesel contents of over 10% in the mixture, with the best results being obtained from the SVM classification. Therefore, the development presented in this paper could become an important technique to improve the discrimination of the feedstock used in biodiesel production and a resource for quality control in industry

Toward Understanding the Influence of Ethylbenzene in <i>p</i>-Xylene Selectivity of the Porous Titanium Amino Terephthalate MIL-125(Ti): Adsorption Equilibrium and Separation of Xylene Isomers

The potential of the porous crystalline titanium dicarboxylate MIL-125­(Ti) in powder form was studied for the separation in liquid phase of xylene isomers and ethylbenzene (MIL stands for Materials from Institut Lavoisier). We report here a detailed experimental study consisting of binary and multi-component adsorption equilibrium of xylene isomers in MIL-125­(Ti) powder at low (≤0.8 M) and bulk (≥0.8 M) concentrations. A series of multi-component breakthrough experiments was first performed using <i>n</i>-heptane as the eluent at 313 K, and the obtained selectivities were compared, followed by binary breakthrough experiments to determine the adsorption isotherms at 313 K, using <i>n</i>-heptane as the eluent. MIL-125­(Ti) is a <i>para</i>-selective material suitable at low concentrations to separate <i>p</i>-xylene from the other xylene isomers. Pulse experiments indicate a separation factor of 1.3 for <i>p</i>-xylene over <i>o</i>-xylene and <i>m</i>-xylene, while breakthrough experiments using a diluted ternary mixture lead to selectivity values of 1.5 and 1.6 for <i>p</i>-xylene over <i>m</i>-xylene and <i>o</i>-xylene, respectively. Introduction of ethylbenzene in the mixture results however in a decrease of the selectivity

Structural Features and Optical Properties of All-Inorganic Zero-Dimensional Halides Cs₄PbBr_6–<i>x</i>I<i>_x</i> Obtained by Mechanochemistry

Despite the great success of hybrid CH3NH3PbI3 perovskite in photovoltaics, ascribed to its excellent optical absorption properties, its instability toward moisture is still an insurmountable drawback. All-inorganic perovskites are much less sensitive to humidity and have potential interest for solar cell applications. Alternative strategies have been developed to design novel materials with appealing properties, which include different topologies for the octahedral arrangements from three-dimensional (3D, e.g., CsPbBr3 perovskite) or two-dimensional (2D, e.g., CsPb2Br5) to zero-dimensional (0D, i.e., without connection between octahedra), as the case of Cs4PbX6 (X = Br, I) halides. The crystal structure of these materials is complex, and their thermal evolution is unexplored. In this work, we describe the synthesis of Cs4PbBr6–xIx (x = 0, 2, 4, 6) halides by mechanochemical procedures with green credentials; these specimens display excellent crystallinity enabling a detailed structural investigation from synchrotron X-ray powder diffraction (SXRD) data, essential to revisit some features in the temperature range of 90–298 K. In all this regime, the structure is defined in the trigonal R3̅c space group (#167). The presence of Cs and X vacancies suggests some ionic mobility into the crystal structure of these 0D halides. Bond valence maps (BVMs) are useful in determining isovalent surfaces for both Cs4PbBr6 and Cs4PbI6 phases, unveiling the likely ionic pathways for cesium and bromide ions and showing a full 3D connection in the bromide phase, in contrast to the iodide one. On the other hand, the evolution of the anisotropic displacement parameters is useful to evaluate the Debye temperatures, confirming that Cs atoms have more freedom to move, while Pb is more confined at its site, likely due to a higher covalency degree in Pb–X bonds than that in Cs–X bonds. Diffuse reflectance ultraviolet–visible (UV–vis) spectroscopy shows that the optical band gap can be tuned depending on iodine content (x) in the range of 3.6–3.06 eV. From density functional theory (DFT) simulations, the general trend of reducing the band gap when Br is replaced by I is well reproduced

Effect of the Methylation and N–H Acidic Group on the Physicochemical Properties of Imidazolium-Based Ionic Liquids

This work presents and highlights the differentiation of the physicochemical properties of the [C₁Him]­[NTf₂], [C₂Him]­[NTf₂], [¹C₁²C₁Him]­[NTf₂], and [¹C₄²C₁³C₁im]­[NTf₂] that is related with the strong bulk interaction potential, which highlights the differentiation on the physicochemical arising from the presence of the acidic group (N–H) as well as the methylation in position 2, C(2), of the imidazolium ring. Densities, viscosities, refractive indices, and surface tensions in a wide range of temperatures, as well as isobaric heat capacities at 298.15 K, for this IL series are presented and discussed. It was found that the volumetric properties are barely affected by the geometric and structural isomerization, following a quite regular trend. A linear correlation between the glass transition temperature, <i>T</i>_g, and the alkyl chain size was found; however, ILs with the acidic N–H group present a significant higher <i>T</i>_g than the [¹C_<i>N</i>‑1³C₁im]­[NTf₂] and [¹C_<i>N</i>³C_<i>N</i>im]­[NTf₂] series. It was found that the most viscous ILs, ([¹C₁Him]­[NTf₂], [¹C₂Him]­[NTf₂], and [¹C₁²C₁Him]­[NTf₂]) have an acidic N–H group in the imidazolium ring in agreement with the observed increase of energy barrier of flow. The methylation in position 2, C(2), as well as the N–H acidic group in the imidazolium ring contribute to a significant variation in the cation–anion interactions and their dynamics, which is reflected in their charge distribution and polarizability leading to a significant differentiation of the refractive indices, surface tension, and heat capacities. The observed differentiation of the physicochemical properties of the [¹C₁Him]­[NTf₂], [¹C₂Him]­[NTf₂], [¹C₁²C₁Him]­[NTf₂], and [¹C₄²C₁³C₁im]­[NTf₂] are an indication of the stronger bulk interaction potential, which highlights the effect that arises from the presence of the acidic group (N–H) as well as the methylation in position 2 of the imidazolium ring