Potassium Compounds Research Articles

N2H4 Derived Sulfonic Acids: Hydrazine Disulfonate, [(SO3)HNNH(SO3)]2-, and Hydrazine Iso-disulfonate, [H2NN(SO3)2]2.

The reaction of hydrazinium sulfate and chlorosulfonic acid in pyridine leads to the pyridinium salt of the hydrazine disulfonate anion, [(SO3)HNNH(SO3)]2-. The salt is the starting material for the preparation of further hydrazine disulfonates, for example of alkaline metals and barium. In all compounds, the [(SO3)HNNH(SO3)]2- anion adopts the gauche conformation. The conformer is chiral but all of the investigated compounds crystallize as racemates. The disulfonate anion can occur in another constitution with the two sulfonate groups attached to only one nitrogen atom. This so-called hydrazine iso-disulfonate, [H2NN(SO3)2]2-, has been prepared through a substitution reaction between potassium imidodisulfonate, K2[HN(SO3)2], and hydroxylamine-O-sulfonic acid, H2NOSO3H. The hydrazine iso-disulfonate anion has been crystallized as potassium and barium compound, respectively. The compounds were characterized by XRD, vibrational spectroscopy, DFT calculations and thermal analyses.

Potassium salts activated lignin-based biochar as an effective adsorbent for malachite green adsorption

Herein, a series of lignin-based porous carbons (LC) were prepared from sulfonated lignin through a simple and environmentally-friendly one-pot activated carbonization together with various potassium compounds as activators, and used for malachite green (MG) adsorption. The results showed that the prepared biochar, especially after K2CO3 activation, exhibited a honeycomb profile with large surface area (2107.6 m2/g) and high total pore volume (1.1591 cm3/g), having excellent efficiency for MG adsorption, and the biggest adsorption capacity was 2970.0 mg/g. The kinetic study together with thermodynamic analysis indicated that the adsorption of MG by LC-K2CO3 conformed to pseudo-second-order model and the adsorption process was spontaneous, feasible, and endothermic. Moreover, LC-K2CO3 also displayed good stability and selectivity, and can selective separate the cationic dye from binary-dye system. Furthermore, the adsorption mechanism proposed in this work manifested that the high-efficient MG adsorption by LC-K2CO3 was a result of multiple actions including hydrogen bonding, electrostatic attraction, π-π interaction and n-π interaction as well as physical absorption. The work not only provide a fundamental theory for dye removal from wastewater, but offered a new insight for lignin valorization.

Influence of «ORGANIC MAX» organic fertilizer on soil condition in Zakarpattia

With a shortage of traditional organic fertilizers and a constant increase in the cost of mineral fertilizers, it is important to find alternative environmentally friendly sources of nutrients. The effectiveness of the new organic fertilizer «Organic MAX», made on the basis of lignite (brown coal) and chicken droppings in the conditions of Zakarpattia region, which provides positive changes in the agrochemical criteria of the soil, has been proposed and studied. Under the influence of bird droppings, the humic substances of lignite go into a physiologically active state and effectively act as plant growth stimulants and sources of nutrients. According to the results of field studies, there is an increase in the effectiveness of this fertilizer with an increase in the content of animal waste: «Organic MAX–20» (lignite + 20% chicken droppings) and «Organic MAX–30» (lignite + 30% chicken droppings). It was found that the application of this fertilizer at a rate of 1 t/ha provided an increase in the content of organic soil matter (humus) by 0.05% for pure lignite, by 0.19% for Organic MAX–20 and by 0.66% for Organic MAX–30. There was also an increase in the content of nutrients: easily hydrolyzed nitrogen by 14.1–55.9 mg/kg; mobile phosphorus compounds at 64.5–109.3 mg/kg; mobile potassium compounds at 64.9–125.5 mg/kg. The effective effect of the fertilizers applied for the next year was revealed despite the high level of nutrient removal by a crop such as corn. The humic component is a nutrient medium for soil bacteria. The active work of microorganisms is the main link in the process of humus formation. After fertilization, there is an improvement in the water-physical properties of the soil, an increase in microbiological activity, as well as a decrease in the negative impact of adverse factors on the development of plants. On acidic soils, first of all, liming must be carried out before fertilizing. The type of this fertilizer is chosen for a specific crop after conducting agrochemical analyzes of the soil. The most effective application of these fertilizers on low-humus low-fertile soils, as well as non-structural ones, since they contribute to the optimization of soil properties. Its use is economically and environmentally feasible. It is possible to recommend environmentally friendly organic fertilizer «Organic MAX» for use in organic farming, the popularity of which in Ukraine is growing every year, to resume soil fertility.

Comparative study of sodium and potassium compounds as promoters for growth of monolayer MoS2 with high crystal quality on SiO2/Si substrate

Monolayer MoS2 is promising candidate for fabrication of optoelectronic devices due to its direct bandgap nature and high carrier mobility. Alkali metal compounds have been demonstrated to be helpful promoters for the growth of large single crystal monolayer MoS2 on SiO2/Si substrate. However, the catalytic mechanism of alkali metal compounds is still under debate. Herein, we compared the surface morphology, optical properties, and electrical properties of monolayer MoS2 flakes grown on SiO2/Si substrate assisted by promoters containing potassium or sodium cations and halogen (chlorine) or non-halogen (hydroxide) anions, i.e. NaCl, NaOH, KCl and KOH. Based on the analysis of existing growth mechanism, we proposed that the alkali metal cation, plays a dominant role in promoting the lateral growth of monolayer MoS2 and obtaining high crystal quality. Furthermore, potassium has a greater promoting effect than sodium. By optimizing growth conditions, monolayer triangular MoS2 flakes with large lateral size over 160 μm were grown assisted by KCl promoter. Raman and PL spectra verified excellent crystal quality of the flakes, with typical electron mobilities of 2.98 and 20 cm2 V−1 s−1 for the back-gated filed effect transistors fabricated on as-grown and fresh SiO2/Si substrates, respectively.

Diversity of Structures and Bonding in Alkali Metal Ureaphosphanes

AbstractWhile organoelement compounds of lithium, sodium and potassium have been much studied for decades and consequently have found forests of applications, those of the heavier alkali metals, rubidium and caesium would barely manage to fill a tree. However, recently the literature has seen some little growth spurts with these metals, hinting at a possible fertile future in areas such as homogeneous catalysis provided more work is put into their fundamental development. Here we report the synthesis and crystal structures of lithium, rubidium and caesium derivatives of the ureaphosphane Ph2PCH2CH2NHC(=O)NHPh, chosen because it offers O, N, P, and π‐coordination sites. Though one may expect such alkali metal compounds to be essentially similar, the caesium complex has novel features where Cs+ engages in a side‐on coordination to the C=O bond and in a weak bond to the P centre, both of which are absent in the Rb structure. Less surprisingly, the lithium derivative is tetrameric in contrast to the infinite networks of the rubidium and caesium structures. All alkali metal derivatives were made with deprotonating the ureaphosphane by a suitable base, including the sodium and potassium complexes though these two complexes could not be obtained in a crystalline form.

BIO PROTECTIVE TREATMENT OF WOOD

The article covers issues related to biological protection of wood. It is shown that wood, especially chopped (dead) wood is exposed to both external natural factors and the action of various microorganisms. Natural factors, especially ultraviolet rays of solar radiation, change the chemical composition of wood and destroy lignin as the least stable part of wood. Wood is more intensively destroyed by various microorganisms ‒ bacteria and fungi. Wood contains many nutrients - starch, sugar, fats, compounds of nitrogen, phosphoric acid, sulfur, potassium, calcium and magnesium. All of them are an excellent environment for the settlement and reproduction of various microorganisms. It is noted that among hardwoods, beech wood is most negatively affected by microorganisms, especially in the warm period of the year. This wood is a valuable breed from which furniture, planed veneer and various parts and products in the construction industry are made. Therefore, it is very important to keep it intact and attractive for a long time by treating it with bioprotective agents. The purpose of the research is to determine the biostability of beech wood after its treatment with bioprotective agents. An analysis of the biological destruction of wood and the use of protective materials was conducted and it was established that the paucity of data to explain and describe the bioprotection process, the neglect of environmentally safe means leads to the biodestruction of wooden structures under the action of microorganisms. A bioprotective agent based on copper oxychloride, nickel sulfate and soda ash was used in a certain ratio of components. Control and treated samples of beech wood were placed in the prepared soil and after 60 days the weight loss of the samples was determined. Studies have shown that the biostability of beech wood treated with a bioprotective agent is 4.3 times higher than that of untreated samples. The idea of the reproduction of microorganisms in the material and their death has been revealed, which, accordingly, shows changes in the metabolic processes of the vital activity of microorganisms. It has been established that the use of treated surfaces oil-wax and azure reduces the biodegradation process by more than 8 times for untreated samples. Keywords: beech wood, bioprotective treatment, bioprotective agents, biostability determination method, mass loss, treatment efficiency.

Ammonothermal Synthesis and Solid-State NMR Study of the Imidonitridosilicate Rb3Si6N5(NH)6.

The imidonitridosilicate Rb3Si6N5(NH)6, being only the second representative of this compound class, was synthesized ammonothermally at 870 K and 230 MPa. Its crystal structure was solved from single-crystal X-ray diffraction data. The imidonitridosilicate crystallizes isotypically with the respective potassium compound in space group P4132 with the lattice parameter a=10.9422(4) Å forming a three-dimensional imidonitridosilicate tetrahedra network with voids for the rubidium ions. The structure model and the presence of the imide groups were verified by Fourier-Transform infrared (FTIR) and magic-angle spinning (MAS) NMR spectroscopy, using cross polarization 15N{1H} and 29Si{1H} MAS NMR experiments. Rb3Si6N5(NH)6 represents a possible intermediate during the ammonothermal synthesis of nitridosilicates. The characterization of such intermediates improves the understanding of the reaction pathway from ammonothermal solutions to nitrides. Thus, the ammonothermal synthesis is an alternative approach to the well-established high-temperature synthesis leading to the compound class of nitridosilicates.

Effect of Adding Stevia Sweetener (Stevia rebaudianna) and Arabic Gum Filler on the Physicochemical Properties of Chayote Squash (Sechium edule) Powder Drink

Chayote squash (Sechium edule) is renowned for high potassium (125 mg), fiber (1.7 g), and antioxidant compounds including flavonoid, polyphenol, tannin, and saponin. The plant has the potential to be processed into powder drink with the addition of stevia powder and arabic gum . Stevia provides 200 – 300 times the sweetness of sucrose and non-calorie, while arabic gum is used as a bulking agent to improve the physical character of powder drink. Therefore, this study aimed to determine the physicochemical properties of chayote squash powder drink with variations of stevia powder and arabic gum. The method used was a two factorial complete randomized design with variations in stevia powder of 2% and 4% as well as arabic gum of 10% and 15%. Each treatment was repeated three times and powder drink was processed using foam mat drying method at 70 °C for 6 hours. The parameters observed include yield, water holding capacity (WHC), solubility, hardness, springiness, water content, ash content, pH, total dissolved solids (TDS), and antioxidant activity, while the data were analyzed using Two-way ANOVA without interaction. The results showed that the addition of stevia powder and arabic gum significantly affected yield, WHC, water content, pH, TDS, and antioxidant activity. However, no significant effect was observed on solubility, hardness, springiness, and ash content. The best formulation was found to be S2A2 containing 4% stevia powder + 15% arabic gum, with 9.69% yield, 37.65% solubility, WHC 37.44%, hardness 257.61 N, springiness 0.683, moisture content 5.02%, ash content 5.43%, pH 5.73, TDS 5.7 °Brix, and antioxidant activity of 143.00 ppm.

METHOD OF ACCOUNTING SOIL-AGROCHEMICAL POTENTIAL FOR OPTIMIZING THE STRUCTURE OF LAND USE OF THE VOLOZHINSK DISTRICT OF THE REPUBLIC OF BELARUS

The article discusses one of the ways to assess the condition of soil cover to improve the efficiency of land management using the example of the Volozhin region of the Republic of Belarus. A comprehensive assessment of the agrochemical and natural potential of the soil is proposed by means of typing the soil cover depending on agrochemical indicators (pHKCl, humus content, mobile compounds of phosphorus and potassium) and a quality score reflecting the natural state of the soil. Using geostatistical methods, the values of agrochemical indicators were interpolated from elementary areas into areas of soil varieties of agricultural lands and classified according to the degree of content of agrochemical elements that made up the agrochemical potential (AP). After crossing the AP with the bonitet score, 9 groups of soils were identified according to soil-agrochemical potential (SAP), of which the largest share (58,2 %) is occupied by soils with average potential (61,950 ha). Based on the results of a spatial assessment of the PAP, it was determined that sod-podzolic and sod-podzolic swampy soils developing on light loams and cohesive sandy loams have the greatest potential. It was also revealed that areas with low PAP gravitate towards the most dissected areas of the terrain with sandy and cohesive sandy soils. Based on the typification carried out, the main types of preferred land use in the Volozhin region were determined: more than half of the agricultural land can be used for intensive agricultural use for arable land (52,1 %) and meadows (12,5 %), traditional land use is possible for 29,3 % territories and only 6,2 % of lands require the use of soil protection farming systems, primarily focused on erosion-hazardous areas of the area.

Growth of L asparagine monohydrate doped potassium dihydrogen phosphate semiorganic crystals and its structural, thermal and optical properties

A novel semiorganic crystal is harvested by doping organic amino acid L asparagine monohydrate (LAM) with inorganic compound Potassium dihydrogen phosphate (KDP) by adopting slow evaporation method. Rietveld refinement of the XRD data was performed and the structural study exhibits single phase nature of the LAM doped KDP (LAM-KDP) crystals with a slight decrease in c-axis of the unit cell parameters. Other crystallographic parameters such as crystallite size and strain were also evaluated. The interaction of LAM with KDP was studied from FT-IR analysis by detecting functional groups. The constituting elements of the crystal were identified by energy dispersive X-ray (EDX) analysis. Etching study has been employed to study surface morphology of these crystals. From UV–vis transmittance data, optical band gap and different optical constants like Urbach energy, dielectric constants, electrical and optical conductivities were evaluated. Optical transparency of the LAM-KDP crystals is observed to increase. The third order nonlinear susceptibility χ(3) and nonlinear refractive index n2 of the grown crystals have been predicted using empirical Miller's rule. The value of χ(3) has increased from 1.87 × 10−13 esu to 4.29 × 10−13 esu due to LAM doping. Change in enthalpy (ΔH), change in Gibb's free energy (ΔG) and activation energy Ea during chemical reaction were calculated by thermogravimetric analysis (TGA). Thermal decomposition characteristics of the crystals were analyzed by differential scanning calorimetry (DSC). The high transparency of LAM-KDP crystals in the entire visible spectrum and larger values of nonlinear susceptibility χ(3) and nonlinear refractive index n2 make the synthesized crystal applicable for NLO and optoelectronic devices applications.

In defense of platinum: Amino acidic polydentate ligands as a shield against sulphur-donor nucleophilic attacks

The interactions of sulfur-containing peptides and proteins with platinum-based anticancer agents are of significant interest in the field of bioinorganic chemistry. We previously modified the lead compound potassium {trichlorido[η2-(but-3-en-1-yl)-2-acetoxybenzoate]platinate(II)} (Pt-butene-ASA) by exchanging two chlorido ligands for an amino acid chelating ligand to improve its stability in aqueous solutions. In the current study, we demonstrate how this amino acid ligand strengthens the inertness of this class of complexes against sulfur-containing compounds. We incubated four complexes, each bearing an amino acid chelating ligand, with various sulfur-containing compounds of biological interest, such as DMSO, methionine, glutathione, and substance P. The reactions were monitored using NMR spectroscopy and mass spectrometry, allowing the identification by combination with IR ion spectroscopy of exotic pentacoordinate platinum(II) complexes as reaction intermediates. The results indicated that the reactivity of complexes 1–4 ((ethene,N-trans)(l-alaninato-N,O)chlorido(η2-ethene)platinate(II), (ethene,O-trans)(β-alaninato-N,O)chlorido(η2-ethene)platinate(II), (l-histidinato-N,N)chlorido(η2-ethene)platinate(II), and (olefin,N-trans)(l-alaninato-N,O)chlorido(η2-(but-3-en-1-yl)-2-acetoxy benzoate)platinate(II), respectively) is determined by the inner coordination sphere, and the addition of an amino acid ligand significantly reduces the rate of nucleophilic substitutions by sulfur-containing nucleophiles. In particular, the N,ethylene-trans isomers reacted only to a low extent with the free thiol in glutathione, while the O,ethylene-trans isomer was completely consumed within 2 h. Complex 4, the new lead compound, showed low reactivity towards S-nucleophiles in general, which confirms the concept of using amino acids as biocompatible bidentate ligands to adjust the reactivity and stability of this kind of metallodrugs.

Synthesis, crystal structure, and thermodynamic properties of two new selenate chlorides: M2Cu(SeO4)Cl2 with M = K and Rb

Two new selenate chlorides have been prepared for the first time by hydrothermal method. Their crystal structures have been determined. Both compounds are related to the chlorothionite mineral structure type but not isostructural to each other. K2Cu(SeO4)Cl2 crystallize in the orthorhombic system with the space group Pnma (#62) and unit cell parameters a = 7.7941(2)Å, b = 6.1297(2) Å, c = 16.6644(5) Å, V = 796.15(4) Å3, Z = 4 whereas Rb2Cu(SeO4)Cl2 crystallize in monoclinic system, P21/n (#14), and parameters a = 8.0701(3), b = 12.9474(5), c = 16.9354(7), β = 103.657(2)°, V = 1719.49(12) Å3, Z = 8. Potassium compound are isostructural to the related sulfate chloride, while rubidium selenate is differ from their sulfate analogue and from prototype compound K2Cu(SO4)Cl2. Both examined crystal structures feature copper ions in planar coordination CuO2Cl2 which form isolated magnetic chains along ⟨0 1 0⟩ direction in the structure. The study of M2Cu(SeO4)Cl2 was carried out in measurements of magnetic susceptibility χ(T) = M/B in the temperature range 2–350 K, magnetization M(B) at 2 K and specific heat Cp(T) in the range 2–120 K. At lowering temperature, the magnetic susceptibility exhibits no anomalies and follows by Curie law. An increase of the Cp(T) curve below 3 ÷ 8 K indicates the release of magnetic entropy. The study of thermodynamic properties unexpectedly shows that the investigated selenates M2Cu(SeO4)Cl2 (M = K and Rb) behave like paramagnets and the interaction between copper ions in the structural chains is negligible, opposite related sulfates demonstrating 1D magnetic behavior for Cu2+ magnetic ions.

Study on the effect of potassium compound on the combustion characteristics of HTPB composite solid propellant

Study on the effect of potassium compound on the combustion characteristics of HTPB composite solid propellant

Degradation of solid oxide fuel cell anodes by the deposition of potassium compounds

Alkali contents with low melting points in the ash of woody biomass vaporize during the biomass gasification process, damaging various downstream energy conversion devices, such as the solid oxide fuel cells (SOFCs). In this study, the degradation of SOFC anodes by the deposition of potassium compounds (KCl, K2CO3, and KOH) was investigated. An aqueous solution of potassium compounds was dripped onto the anode surface of the SOFC button cell at room temperature. After drying at 343 K, 6.964 × 10-6 mol KCl, 6.964 × 10-6 mol KOH, and 3.482 × 10-6 mol K2CO3 was deposited on the anode. Button cells with the deposition of K compounds were employed for power generation experiments at 1023 K with the supply of artificial syngas from biomass gasification. After the power generation experiments, the surface structures of the anodes were microscopically analyzed using the SEM and EDS. As a result, K compounds hardly affected the OCV of SOFC. With the addition of KCl, no apparent change in the anode structure was observed, and only a slight KCl deposit was detected. However, chloride tends to be chemisorbed on Ni, increasing the ohmic resistance as well as the adsorption/desorption resistance. However, KOH transformed to K2CO3 and then remained massively on the anode, which was clearly observed in the SEM images. K2CO3 significantly decreased the cell voltage under a current density of 100 mA·cm−2. Through impedance analyses, this voltage drop was mainly attributed to the ohmic resistance and gas diffusion resistance. However, there is no evidence that this deposit degrades Ni particles.

Isolation and molecular characterization of microorganisms with biofertilizer potential

Biofertilizers are microbial-agro products containing mixed culture of microorganisms that promote plant growth, yield, soil quality and disease control. This study aimed to isolate, identify and screen microorganisms with biofertilizer potentials for application in farms. Soil samples were collected from farmland and waste-dump soils around University of Port Harcourt. The various microorganisms were isolated and estimated using nutrient agar, potato dextrose agar, cetrimide agar and Ashby’s agar. The microorganisms were screened for biofertilizer potentials based on nitrogen fixation, potassium and phosphate solubilization using Pikovskaya media. The results obtained from this study showed that thefarmland soil sample had a total heterotrophic bacterial and fungal counts of 5.045±0.02 and 4.220±0.02 Log10Cfu/gwhile the corresponding values in the waste-dump soil was 4.890±0.30 and 3.505±0.30 Log10Cfu/g respectively. After screening, the microorganisms with biofertilizer potentials were identified as Aspergillus niger, Penicillium chrysogenum, Bacillus cereus, Bacillus licheniformis, Pseudomonas fluorescens and Azotobacter chroococcum. Findings from this study have demonstrated that the microorganisms isolated from the farmland soil were more adept at nitrogen fixation and solubilizing insoluble potassium and phosphate compounds than their counterparts in waste-dump soil. These microorganisms have shown potentials to improve soil fertility and crop productivity in a sustainable way.

Characterization of the decomposition behaviors of catalytic pyrolysis of alkaline lignin with the addition of different concentrations of potassium

Investigating the influence of potassium concentration on alkali lignin pyrolysis is beneficial for advancing the technology of biomass catalytic pyrolysis. This study examined the catalytic effects of different concentrations of various potassium compounds on alkali lignin pyrolysis. The impregnation method was employed to load potassium compounds (KCl, K2CO3, and CH3COOK) onto alkali lignin at varying concentrations. The results showed a significant influence of potassium concentration on the catalytic pyrolysis of lignin. Increasing the potassium concentration resulted in higher pyrolysis char yield and lower pyrolysis gas yield. Furthermore, the pyrolytic char with a high concentration of potassium exhibited a distinct surface pore structure that was noticeably eroded by potassium. Furthermore, with an increase in potassium concentration, the removal of side chains, including methoxy, acetyl, and hydroxyethyl groups, became increasingly pronounced, resulting in higher yields of CO2 and phenol. The elevated potassium concentration facilitated the depolymerization of lignin through Cβ-O bond cleavage, promoted the decomposition of intermediate products, and enhanced the formation of small molecule products. Ultimately, a hypothetical mechanism explaining the influence of potassium concentration on alkali lignin pyrolysis was proposed. This study establishes a scientific foundation for the high-value utilization and resource development of alkaline lignin.

Efficiency of Bacillus mucilaginosus isolated from the soil in dissolving potassium in its microenvironment

Soil bacteria have an effective role in dissolving soil potassium. Bacillus mucilaginosus plays an effective role in dissolving potassium in the soil so that the plant may absorb it easily. The present study aimed to test the efficiency of bacteria in dissolving potassium present in the soil surrounding the roots of crops. B. mucilaginosus was isolated and diagnosed from the rhizosphere soil of Celery, Wheat, Basil and Alfalfa plants. The diagnosis included studying the isolates' culture, microscopic and biochemical characteristics. The laboratory study also included testing the efficiency of these bacterial isolates in dissolving potassium compounds in Modified Aleksandrov agar medium and estimating the dissolution coefficient. The results of isolation and identification of bacteria isolated from 19 out of 50 soil samples planted with different crops (Celery, Wheat, Basil and Alfalfa) showed that 8 isolates could dissolve potassium. The results of the microscopic examination of these eight isolates showed that they were sticky in shape, positive for Gram-staining, forming spores and the capsule, while the movement examination showed that they were positive for these tests (movement test). The biochemical tests and cultural characteristics showed that the eight isolates bear the characteristics of B. mucilaginosus. The results showed that the dissolution coefficient of potassium for the different isolates ranged between 2.28 and 1.14, while the type of sugar added to the culture medium increased the efficiency of bacterial isolates for potassium solubility. The study demonstrated the bacteria's efficiency in the rhizosphere region in dissolving potassium, which helps the plant use it easily.

Porous carbon generation by burning starch-based intumescent flame retardants for supercapacitors

Exploring novel methods for preparing porous carbon is essential for developing electrode materials. Herein, a general strategy for preparing porous carbon via flame-burning carbonization of a three-in-one intumescent flame retardant (IFR) is proposed. The IFR comprising biomass (starch, agar, cotton fiber, and cottonseed meal as carbon sources), Zn3(BO3)2 (as an acid source) and K2CO3 (as a gas source) is carbonized directly by a flame gun in 5 min to prepare porous carbon. The carbon layer is formed by esterification, depolymerization, ring opening, polycondensation and aromatization. Concurrently, the molten state of the boron and potassium compounds prevents the carbon from burning out. Benefited from the doping, templating, and activating effects of Zn3(BO3)2 and K2CO3, the samples exhibit a layered porous structure and multi-heteroatom doping, demonstrating excellent capacitive properties. The starch-based K2CO3-glycol-DMSO deep eutectic solvent gel electrolyte is synthesized, and the fabricated solid-state capacitor exhibits high energy density (24.5 Wh kg−1), a large voltage window (2.2 V), and a wide temperature operating range (-25 °C to 75 °C). Moreover, the four types of IFRs are amenable to the proposed burning carbonization method, and it is expected that diverse carbon materials will be synthesized using other IFRs in the future.

ДЕГИДРИРОВАНИЕ ЭТИЛБЕНЗОЛА В ПРИСУТСТВИИ ЖЕЛЕЗООКСИДНЫХ КАТАЛИЗАТОРОВ, ПРОМОТИРОВАННЫХ КАЛИЕМ, ЦЕРИЕМ И МОЛИБДЕНОМ: КИНЕТИЧЕСКОЕ МОДЕЛИРОВАНИЕ

The present work is devoted to assessing the effect of the chemical composition of iron oxide catalysts promoted with potassium, cerium and molybdenum on their activity, quantified as ethylbenzene conversion, and selectivity of ethylbenzene dehydrogenation and interpreting the results obtained using kinetic modeling. The concentrations of the components of the reaction mixture, the conversion of ethylbenzene and selectivity of the ethylbenzene dehydrogenation were experimentally determined in the presence of synthesized iron oxide catalysts. A kinetic model of the process has been developed in the form of a system of differential equations that describes changes of the reaction system components concentration according to the mass action law. The experimental concentrations of the reaction mixture components, the ethylbenzene conversion and selectivity were described by the kinetic model by the use in the model of the following type of dependencies of the reaction rate coefficients on temperature: k i = k i0 T n i exp⁡(- B i T m i ) , where ki0, Bi, ni, mi are coefficients independent of temperature; T is the process temperature, K. As a result of kinetic modeling, the following patterns were established. The rate of the forward reaction of ethylbenzene dehydrogenation C6H5-C2H5 ⇆ C6H5-C2H3 + H2 is much greater than the rate of the reverse reaction, so chemical equilibrium in the ethylbenzene dehydrogenation reaction is not achieved. The effect of the reverse reaction on the kinetics of the ethylbenzene dehydrogenation process is minimal. The rate of the direct reaction of ethylbenzene dehydrogenation C6H5-C2H5 ⇆ C6H5-C2H3 + H2 is much higher than the rates of the reactions C6H5-C2H5 → C6H6 + C2H4 and C6H5-C2H5 + H2 →C6H5-CH3 + CH4. In this regard, the conversion of ethylbenzene is determined by the rate coefficient of the forward reaction in the reversible reaction of ethylbenzene dehydrogenation C6H5-C2H5 ⇆ C6H5-C2H3 + H2. The selectivity is determined by the ratio of the rate (or the ratio of the rate coefficient) of the direct reaction of ethylbenzene dehydrogenation C6H5-C2H5 ⇆ C6H5-C2H3 + H2 to the sum of the rates (or the sum of rate coefficient) of the direct reaction of ethylbenzene dehydrogenation and the dealkylation reaction of ethylbenzene C6H5-C2H5 ⇆ C6H6 + C2H4. It has been shown that an increase of the ethylbenzene conversion can be achieved, first of all, by promoting the iron oxide catalyst with the potassium compound. Pre-exponential factors and activation energies for all iron oxide catalysts promoted with the potassium compound do not change when cerium or molybdenum compounds are introduced into the catalyst, that is, in the process under consideration, the contribution of cerium and molybdenum compounds to the chemical properties of the iron oxide catalyst is insignificant.

Experimental exploration of potassium compounds in the vicinity of a burning biomass pellet: From near-surface to downstream

The concentrations of gas-phase potassium hydroxide (KOH), potassium chloride (KCl) and atomic potassium (K(g)) were quantitatively measured from the near-surface to downstream area of burning pinewood pellets by a newly developed photofragmentation tunable diode laser absorption spectroscopy (PF-TDLAS) technique to reveal the original form of the released potassium. The novel arrangement of the PF-TDLAS system enabled a spatial resolution of ∼1 mm3, which made it possible to obtain temporal release profiles of K(g)/KOH/KCl at different heights above the burning pellet surface. Surface temperature and mass loss of the wood pellet as well as the gas temperature at measurement points were measured simultaneously. During the devolatilization stage, the release of all three potassium species was observed, with each of them accounting for ∼1/3; while in char oxidation stage, the release of KOH was dominant, but the release intensity was strongly influenced by the local oxygen content. The results from different measurement heights showed there was a notable difference in potassium release profiles of different potassium species over the near-surface area, where the detected potassium forms were the best representative of the originally released forms of potassium. For a period of time during the devolatilization stage, only K(g) was detected in the near-surface area, and the concentration was significantly lower than the downstream area where KOH and KCl coexisted. This suggested that a large amount of potassium might leave the pellet as organic-K, which cannot be detected by the PF-TDLAS method. During char oxidation stage, the total potassium concentration at the near-surface area was also lower than the downstream area, but it was due to the lack of oxygen at the measurement position. A potassium release mechanism during the devolatilization stage of biomass combustion was proposed based on the experimental measurements, and the results also indicated the importance of spatially resolved measurement.