Papers by Keyword: Methanol

Abstract: A promising approach to meet rising energy demands while mitigating environmental risks from greenhouse gases is the conversion of carbon dioxide into methanol through CO₂ hydrogenation. Previous studies have demonstrated that unsupported subnanometer Pd_x clusters exhibit excellent performance in this conversion. However, the influence of support materials on the activity of Pd clusters remains poorly understood. In this study, we compare the kinetics of CO₂ hydrogenation to methanol using unsupported Pd₇ clusters and those supported by metal oxides, specifically Pd₄/In₂O₃(110) and Pd₃/TiO₂(110). Microkinetic simulations, based on available energetic data from the literatures, reveal that Pd₄/In₂O₃(110) delivers superior kinetic performance, followed by Pd₇ and Pd₃/TiO₂(110). These findings demonstrate that the choice of support material plays a critical role in dictating the reaction pathway and rate for supported Pd cluster catalysts.

Abstract: Continuous emissions of carbon dioxide (CO₂) into the atmosphere brought several environmental problems. Photoconversion of CO₂ not only can produce value-added products (i.e. methanol) but also aim to reduce the environmental problems caused by CO₂. The present work demonstrates the preparation of N-Bi co-doped carbon quantum dots/titanium dioxide (N-Bi co-doped CQDs/TiO₂) as a visible-light driven photocatalyst for the photoconversion of CO₂ to methanol. Hydrothermal-synthesized N-Bi co-doped CQDs were incorporated into TiO₂ nanoparticles through facile mixing method. The loading of CQDs in TiO₂ matrix resulted in a decrease of band gap to 2.75 and 2.65 eV for N-CQDs and N-Bi CQDs, respectively. Gas chromatography equipped with flame-ionization detection (GC-FID) analysis showed a methanol yield of 17 µmol/gcat from the photoconversion experiment using N-Bi-CQDs/TiO₂ photocatalyst composite. The performance of composite was assigned to the loading of N-Bi co-doped CQDs, which reduced the electron-hole recombination in TiO₂. Doping of N-Bi played an important role in localizing the photogenerated electron-holes, essentially enhancing the electron transfer at the CQDs/TiO₂ interface. Thus, our work could provide insight into the application of CQDs-based photocatalysts in the visible-light driven photocatalytic conversion of CO₂ to value-added products.

Abstract: Photocatalytic reduction of carbon dioxide (CO₂) to solar fuel is a potential approach to overcome the problem of high CO₂ concentrations; however, the process still faces enormous challenges, such as low light absorption efficiency and high carrier recombination rates. Herein, Fe-doped carbon dots were prepared by a one-step hydrothermal method using sodium citrate, ethylenediamine, and FeCl₃·6H₂O as raw materials. The performances of the resulting materials toward the photocatalytic reduction of CO₂ were investigated and the results showed that Fe doping can regulate the energy band structure of CDs. However, the conduction band potential of Fe-carbon dots displayed no obvious influence except in terms of band gap. Moreover, Fe doping reduced the recombination rate of photo-generated carriers in CDs, increased the mobility of photo-generated carriers, and declined the resistance during the migration of photo-generated electrons. The photocatalytic reduction performances of CO₂ illustrated conversion yield of CO₂ to CH₃OH reaching 289.81 μmol·g (cat)^-1·h^-1 using Fe-CDs-13.0 catalyst, a value 2.36-fold higher than that of CDs. We found that Fe-CDs were synthesized by modulating the energy band structure of CDs. Fe-CDs improve visible light utilization and apply them to the photocatalytic reduction of CO₂.

Abstract: The monooxidation of methane into methanol was carried out on biomimetic heterogeneous catalyst – iron pentafluorotetraphenylporphyrin on Al₂O₃ (ImtOH), at atmospheric pressure and temperatures of 200-350°C, which resulted in liquid one-carbon compounds CH₃OH (19.2%), CH₂O (1.55%), CH₃OCH₃ (8.2%) with high selectivity and are widely used in the chemical industry. In order to establish the routes of these products formation and the mechanism for the methane conversion into them, the investigation of the methanol conversion reaction was carried out, as an intermediate compound of the methane oxidation, under identical conditions on the same catalyst.The result was only dimethyl ether with 100% selectivity. This proved that in this reaction system, methanol obtained from the methane monooxidation is converted only into dimethyl ether, and formaldehyde, in parallel with methanol, is formed from methane. The mechanisms of the elementary stages of the formation of methanol, formaldehyde and dimethyl ether on the surface of the bioimitator through the formation of an active complex (ImtOOH) are presented, in which the unity of the mechanisms of redox and acid-base catalysis traced within the framework of the principle of the bond redistribution chain (BRC), similar to enzymatic reactions.

Abstract: This article presents the dependence of the speed of sound u/m•s^-1 of binary solutions of 1-ethyl-3-methylimidazolium methanesulfonate [EMIM][MeSO3], 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF6] or 1-Butyl-3-methylimidazolium tris(pentafluoroethyl) trifluorophosphate [BMIM][FAP] with methanol. The experiments were carried out at temperatures T=(278.15–343.15) K using a vibration densimeter and an Anton-Paar DSA 5000M sound speed meter with an error of Δu/u=0.1 m•s^-1. The studied solutions are intended for use in solar thermal collectors, absorption refrigeration units and heat pumps.

Abstract: The textile industry has been weaving polymer optical fibers (POFs) into plane fabric for many years for lighting and decoration. To apply POF-incorporated fabrics in a larger field of application, it is necessary to improve the side illumination of POF-incorporated fabrics. It has been reported that the chemical etching method is one method to enhance the illumination of POFs, while there is little research related to the application of chemical etching to enhance the illumination of POF-incorporated fabrics. In this work, the end emitting POFs (EEPOFs) were used as weft yarns, and polyethylene terephthalate (PET) yarns were used as warp yarns. The POF-incorporated woven PET fabrics were successfully fabricated with a 1/3 twill structure and then treated with a mixture of acetone and methanol (volume ratio: 1:1) for 1 min. The morphology and side illumination of etched POF-incorporated PET fabrics were investigated. As a result, the acetone/methanol mixture destroyed the cladding layer of EEPOFs, and the luminance of etched POF-incorporated PET fabrics was increased by more than 50 %. Besides, acetone/methanol etching resulted in a higher side illumination attenuation behavior.

Abstract: Photocatalytic CO₂ reduction to solar fuel is a potential way to overcome the problem of high carbon dioxide concentrations; however, the process still faces enormous challenges, such as the low light absorption efficiency and high carrier recombination rates. This work synthesized tetraphenylporphyrin-based carbon dots (TPP-CDs) for the photocatalytic CO₂ reduction to CH₃OH under simulated sunlight to extend the absorption region of the CDs. The conduction band of the TPP-CDs has a sufficiently negative reduction potential to reduce CO₂. TPP-CDs containing 1 wt.% TPP achieved an optimum CH₃OH production rate of 173.35 μmol·g_cat^-1·h^-1, with a remarkable 2.06-fold increase compared to pristine CDs without TPP. In this study, TPP-CDs were synthesized by changing the CD precursors to improve the utilization of visible light and apply them to the photocatalytic reduction of CO₂.

Abstract: The article analyzes the reasons hindering the mass use of alternative fuels in the field of energy consumption of domestic transport, which for the most part have lower energy and kinetic indicators of combustion in comparison with traditional fuels. A new approach to solving the problem of improving the environmental and energy-saving indicators of combustion of alternative fuels based on their preliminary thermochemical processing - conversion on board a vehicle is presented. The results of a preliminary analytical study of the parameters of the on-board conversion process for a number of potentially acceptable types of alternative fuels are presented in order to assess the efficiency of this process. The possibility of practical implementation of the proposed process for improving the combustion indicators of alternative fuel with an assessment of its efficiency was tested based on the results of experimental approbation in the conditions of full-scale engine tests. According on the results of the study, the expediency of using this process in transport technologies is justified due to the technical simplicity of its implementation and efficiency. Thermocatalytic reactor is the simplest design of a heat exchanger, the mass and dimensional characteristics of which (in the volume of a conventional muffler) ensure the convenience of its installation in the engine exhaust system. The component composition of these products contains reactive compounds that contribute to the improvement of environmental and energy-saving indicators of the fuel combustion process, and an increase in the efficiency of the engine's operating cycle.

Abstract: Methanotrophs display the ability to consume methane as a carbon source and produce a wide-range of high-value products, e.g. ectoine/hydroxyectoine, poly-b-hydroxybutyrate (PHB), single cell protein, extracellular polysaccharides and lipids. Usually methanotrophs show low specific substrate consumption rates, which restricts their application at pilot and industrial scale. Thus, in order to reduce the time and costs of the cultivation process, it is vital to accelerate the growth of applied organisms. Usually, methanotrophic bacteria cultivations are carried out using fully synthetic mineral mediums (nitrate mineral salts medium (NMS)) without the addition of any growth factors. Potentially, higher biomass growth and substrate uptake rates can be achieved by supplementing the growth medium with vitamins, amino acids etc. or by using more bioavailable substrates.The aim of our research was to study the influence of growth factors such as vitamins, and different nitrogen sources (yeast extract, yeast nitrogen base with/without amino acids and tryptone) on the growth of Methylomonas methanica, Methylomicrobium alcaliphilum and Methylosinus trishosporium.Experiments for studying the influence of growth factors were carried out in shake flasks by varying the medium compositions and analyzing the effects of said variations on the kinetics of the cultivation, e.g. specific biomass growth rate and biomass yield from substrate.Subsequent tests of the developed nutrient medium, which promotes higher biomass growth rates, were carried out in laboratory 5 L bioreactor Methylosinus trishosporium cultivations to study the main process parameters.From the statistical analysis of experimental data it was observed, that supplementation of the growth medium with yeast extract or tryptone, seems to promote the growth rate of methanotrophs, when methanol is used as the main substrate. Furthermore, specific growth rates observed during cultivations in mediums containing vitamins (including cobolamin) also seem to positively affect the biomass growth rate. Based on the results of lab-scale bioreactor cultivations, using the identified medium composition it was possible to achieve a maximal biomass specific growth rate of 0.15 L⸱h^‑1 and productivity of 0.16 g⸱L^-1⸱h^-1.

Abstract: At present, methanol is one of the most basic organic chemical raw materials and energy storage media. With the development of chemical technology and energy storage technology, its application becomes more and more extensive, and the methanol market prospects are unlimited. Industrial-scale methanol is generally prepared by using synthesis gas containing hydrogen, carbon monoxide, and carbon dioxide as raw materials and reacting under a certain pressure, temperature, and catalyst. Therefore, the development of the methanol industry largely depends on the development of catalysts and the improvement of their performance. Metal catalysts are mainly used in the industry for reaction. This article reviews several metal catalysts used to synthesize methanol from syngas. Copper-based and iron-based catalysts are widely used, and the emerging rhodium and its ligand catalysts exhibit good catalytic performance in low-temperature catalysis. In the future, the scientific research team will focus on in-depth research on preparation methods, active centers, catalytic reaction kinetics, durability, metal ligands, raw material prices, etc., to lay a solid foundation for the industrial application of syngas to methanol in advance.