Assessing the condition of coke

As shown by critical analysis, a recent article by Rubchevskii and his colleagues failed to adequately review methods of assessing the condition of coke [1]. A method developed in the central laboratory of the coke plant at OAO EVRAZ NTMK has long been used to assess the condition of coke in terms of the difference in the yield of volatiles (ΔV ^daf ) between coke breeze (V _cb ^daf ) and coke (V _c ^daf ). This method is simpler, more convenient, and more precise than the determination of the bulk yield of volatiles from coke.     

Composition, structure, and properties of Donetsk Basin and United States coal of the same metamorphic stage

The composition, structure, and properties of Donetsk Basin and United States coal of the same metamorphic stage are compared. The samples represent coal from the whole metamorphic series, with vitrinite reflection coefficient R _o = 0.7?C1.8%. Separate regression equations for Donetsk Basin and United States coal describe the relation between the composition (C ^daf , H ^daf , O ^daf ), structural characteristics (C_ar, f _a, ??, and B) calculated from the elementary composition, the technological properties (V ^daf , y, Q _s ^daf ), and the vitrinite reflection coefficient. Significant differences are found in these properties for Donetsk Basin and United States coal of the same metamorphic stage. These differences are mainly due to the different degrees of reduction of the coal. With a vitrinite reflection coefficient up to 1%, the degree of reduction is greater for United States coal than for Donetsk Basin coal. With greater metamorphic development (R _o ?? 1.0%), Donetsk Basin coal is characterized by even lower degrees of reduction.     

Predicting the classification characteristics of coal. Part 3. Gross calorific value of dry,ash-free coal

For 63 samples of Ukrainian, Russian, and imported coal, equations for predicting the gross calorific value Q_s^daf on the basis of the following coal characteristics are developed: W^a, O_d^daf, Q_s^af, and C_ar. The error is within the standard tolerances (σ ≤ 0.3 MJ/kg). With sufficient accuracy, Q_s^daf may be predicted from equations based on petrographic characteristics such as the vitrinite reflectance, the content of liptinitegroup minerals, and the sum of lean macerals (I + 2Sv/3). In these equations, the coefficients correspond to the heat of combustion of the vitrinite components at different metamorphic stages, the liptinite, and the lean macerals.     

Calculation of the enthalpy of formation of coal organic matter

The enthalpy of formation for the organic matter of coals in the coal rank series was calculated from the heat of the complete combustion reaction. Three variants were considered in which the experimental heating values Q _i ^daf and the values found from the correlation equation or calculated using the Mendeleev formula were taken as the heat of the complete combustion of coals.     

Moisture-holding capacity of coals

As a result of a comprehensive study of 63 samples of coal concentrates (from Ukraine, Russia and countries outside the former Soviet Union), it was established that the prediction of the moisture-holding capacity of coals can be appropriately performed according to their values of W ^a, R ₀, O _d ^daf , and O _s ^daf . It was found that the oxidation of coal increased its moisture-holding capacity; however, in this case, the absolute change in this parameter was smaller than the error of its determination (0.5%). Therefore, upon the oxidation of almost 30% of the organic matter of coal, the moisture-holding capacity increased by only 0.4%. There is a close correlation between the maximum moisture capacity of coals and the water pore volume, and this correlation was described by a linear equation in the studies.     

Mass spectrometry study of glasses based on sulfur, phosphorus, and arsenic

The mass spectrometry study of chalcogenide glasses in the P-S binary system and P-As-S ternary system is used to demonstrate that the composition of the gas phase in binary samples is characterized by the conventional spectra of ions, such as PS ₂ ⁺ , P₂S ₇ ⁺ , P₂S ₇ ⁺ and P₄S ₁₀ ⁺ . The introduction of As to the binary glass systems first demonstrated the presence of ions AsPS⁺, AsPS ₄ ⁺ , AS_{2 5} ⁺ and As₂PS₅ ⁺ in the gas phase of the ternary chalcogenide system, which correspond to the ternary compositions AsPS₄ and As₂P₂S₇ in the solid phase.     

IR Spectroscopy in Rank and Group Assignment of Coal

The possibility of express determination of the characteristics V _IR ^daf , R_{o, IR}, y_IR, ΣLC_IR, and A _IR ^d used in the ranking of coal on the basis of IR spectroscopy is assessed for a specific example: Kuznetsk coals of different maceral composition and metamorphic development. The IR characteristics are compared with values obtained by standard methods (V^daf, R_{o, r, y}, ΣLC, and A^d).     

Increased total sulfur content in coal from Donets and other basins

The ash composition is used to assess the conditions of coal-bed formation in the Donets and L’vovsk-Volynsk basins. The experimental data are inconsistent with some aspects of the hypothesis that pyrite and secondary organic sulfur are formed in the coal. The lack of a relationship between the total sulfur content S _t ^d in the coal and the MgO content in its ash does not agree with the notion that sulfates from sea water provide the basis source of nonvegetative sulfur in coal. The actual S _t ^d values do not always correspond to the theory that the source of sulfur depends on the alkalinity of the water and the reducing medium where the deposits accumulate. In the conditions that are most favorable to the formation of coal with high total sulfur content (S _t ^d > 4 wt %) according to the existing hypothesis, the actual value of S _t ^d is no more than 1.5%. The source of pyrite and organic sulfur in coal requires further discussion.     

Interaction Between Cationic and Anionic Surfactants: Detergency and Foaming Properties of Mixed Systems

The micellar and interfacial behavior of mixtures of the anionic surfactant (alcohol ether sulfate, AES) with quaternary ammonium type cationic surfactants dodecyltrimethyl ammonium chloride (DTAC), dodecyl-(2-hydroxyethyl)-dimethyl ammonium chloride (DHDAC), dodecyl-di(2-hydroxyethyl)-methyl ammonium chloride (DHHAC) were investigated by means of surface tension measurements. Various physicochemical properties such as surface activity parameters (CMC, γ _CMC, Г _max, A _min), the micellar and interfacial compositions (x ₁ ^m , x ₁ ^σ ), interaction parameters (β ^m , β ^σ ), and activity coefficients ( \(f_{1}^{m}\) , \(f_{2}^{m}\) , \(f_{1}^{\sigma }\) , \(f_{2}^{\sigma }\) ) were evaluated. The influence of the hydroxyethyl groups of cationic surfactant component on the physicochemical properties of mixed systems has been analyzed. It is observed that the CMC values of the three mixed systems decrease with increases in the number of hydroxyethyl groups of the cationic surfactant component. From the results of β ^σ and β ^m values, the interactions between molecules for the three surfactant mixtures at the air/liquid interface increase in the following order DHHAC/AES < DHDAC/AES < DTAC/AES, but it is the opposite for the interactions in mixed micelles. The detergency and foaming properties of mixed systems were also studied. As expected, complex surfactant systems exhibit good detergency and foaming properties.     

Towards an Understanding of the Reaction Pathways in Propane Ammoxidation Based on the Distribution of Elements at the Active Centers of the M1 Phase of the MoV(Nb,Ta)TeO System

The M1 phase of the MoV(Nb,Ta)TeO system is one of the most effective catalysts for the ammoxidation and selective oxidation of propane to acrylonitrile (AN) and acrylic acid, respectively. The active centers of the M1 phase reside on the ab planes of this crystalline material (i.e., the (001) lattice face). Early on we proposed that the thus located active centers contain all key catalytic elements strategically placed for the conversion of propane to AN. These seven element comprising active centers contain: five metal oxide octahedra (2 V _0.32 ⁵⁺ /Mo _0.68 ⁶⁺ , 1 V _0.62 ⁴⁺ /Mo _0.38 ⁶⁺ , 2Mo _0.5 ⁶⁺ /Mo _0.5 ⁵⁺ ) and two Te⁴⁺??oxygen sites. In this contribution we analyze the various compositional probabilities of the seven element active centers and their additional eight element surroundings and conclude that there are 32 possible compositional arrangements of this 15 element assembly. From the diverse structural arrangements, diverse catalytic properties can be assigned to the individual sites, leading to diverse propane reaction pathways. We conclude that there are 22% AN forming, 22% propylene, 10% waste and 46% inert sites. After normalization these sites are deemed to lead to the following product yields: 41% AN, 41% propylene and 18% waste. The highest experimentally attained AN yield from propane is 42%, employing M1 phase only, which coincides with the predicted value of a concerted mechanism. Higher AN yields are, however, anticipated, up to a lofty upper limit of 82%, by allowing also for a consecutive mechanism (C₃° ?? C ₃ ⁼ ??AN). This possibility can be rationalized on the basis of the existence of vicinal C₃° ?? C ₃ ⁼ /C ₃ ⁼ ??AN sites whose presence is plentiful on the catalytically important ab planes of M1. The placement and efficiency of these sites is, however, not perfect; therefore the upper AN yield limit is not realized in practice. Our analysis of the elemental distribution at the active centers and their immediate surroundings provides us with new insights into the relationship between structure and catalytic reaction mechanisms of the M1 phase and might serve as a guide towards a redesign of the M1 composition, so as to attain higher AN yields from propane. It provides a challenging task for the synthetic chemist.     

The novel [(dME)2(HIM)P]2Ti(IV) complex: synthesize, characterization, and its utility in ROP of d,l-lactide

The novel {2,4-bis(1,1-dimethylethyl)-6-{[(2-hydroxyethyl)imino]methyl}phenoxy}₂ titanium(IV) complex {[(dME)₂(HIM)P]₂Ti(IV)} had been synthesized and characterized by EA, XRF, IR, and NMR methods. The [(dME)₂(HIM)P]₂Ti(IV) complex was reactive and promoted ring-opening polymerization (ROP) of d,l-lactide in the presence of benzyl alcohol (BnOH). And the results showed that ROP of d,l-lactide were produced upon addition of an excess (1–8?equiv.) of external BnOH. The complex showed a living and controlled fashion (M _w/M _n?=?1.15–1.32) for ROP of d,l-lactide and could produce the poly(d,l-lactide) with average molecular weight (M _n) up to 8.87?×?10⁴?g?mol^?1. The mechanism study by ¹H NMR spectrum of poly(d,l-lactide) with terminal benzyl ester group and [(dME)₂(HIM)P]₂Ti(IV) complex revealed that the polymerization proceeded through the traditional activated monomer mechanism and the acyl-oxygen bond cleavage mode of monomer. And the ¹³C NMR spectra and TG/DSC analysis showed that poly(d,l-lactide) was essential atactic and thermal stable polymer.     

Density, ultrasonic velocity, viscosity and their excess parameters of the binary mixtures of N,N-dimethylaniline+1-alkanols (C3-C5), +2-alkanols (C3-C4), +2-methyl-1-propanol, +2-methyl-2-propanol at 303.15K

The density, ultrasonic velocity of sound and viscosity of binary mixtures of N,N-dimethyl aniline (N,NDMA) with 1-propanol, +2-propanol, +1-butanol, +2-butanol, +1-pentanol, +2-methyl-1-propanol, +2-methyl-2-propanol were measured at 303.15 K. These experimental data have been used to calculate excess volume V ^E , excess ultrasonic speeds u ^E , excess intermolecular free length L _f ^E , excess acoustic impedance Z ^E , excess isentropic compressibility κ _s ^E , deviation in viscosity Δη and excess Gibbs free energy of activation of viscous flow (G* ^E ). The values of L _f ^E and κ _s ^E are negative over the wide range of composition for all the binary mixtures, while the values of Z ^E are positive. These results have been used to discuss the nature of interaction between unlike molecules in terms of hydrogen bonding, dipole-dipole interaction, proton-acceptor interaction and dispersive forces. The viscosity data have been correlated using three equations: Grunberg and Nissan, Katti & Chaudhri and Hind et al. The excess/deviations were fitted by a Redlich-Kister equation and the results were analyzed in terms of specific interactions present in these mixtures.     

Ion exchange and charge transport properties of polymeric tris(4-vinyl-4′-methyl-2,2′-bipyridine) ruthenium(II) films

Multiply charged electroactive anions [IrCl ₆ ^2? , Fe(CN) ₆ ^3? , and W(CN) ₈ ^4? ] are electrostatically incorporated in polymeric films of tris(4-vinyl-4′-methyl-2,2′-bipyridine) ruthenium(II) [poly-Ru(vbpy) ₃ ²⁺ ] from aqueous trifluoroacetate solution. Values of apparent diffusion coefficients (D _ct) and heterogenous electron transfer rates (k _et) are measured for these anions as a function of their relative concentration (Γ _M/Γ _Ru) in the film.D _ct andk _et decrease systematically asΓ _M/Γ _Ru increases in a manner that is independent of charge and chemical identity of the ion. This result suggests that a nonchemical process, presumably electrostatic cross-linking, limits diffusional motion and is responsible for the decrease inD _ct andk _et with increasing anion content. Protonated polyvinyl-pyridine films exhibit similar ranges and variations inD _ct andk _et, which suggest similar structures and mechanisms of charge transport for these films and poly-Ru(vbpy) ₃ ²⁺ .     

Synthesis and single-crystal structure of lead oxide nanoclusters in zeolite Y, |Pb 15.5 2+ (Pb4O4(Pb 16/19 2+ Pb 3/19 4+ )4)4.75|[Si117Al75O384]-FAU

A single crystal of excessively Pb²⁺-exchanged zeolite Y (|Pb _15.5 ²⁺ (Pb₄O₄(Pb _16/19 ²⁺ Pb _3/19 ⁴⁺ )₄)_4.75|[Si₁₁₇Al₇₅O₃₈₄]-FAU) was prepared by exchange of Na–Y (|Na₇₅|[Si₁₁₇Al₇₅O₃₈₄]-FAU, Si/Al = 1.56) with an aqueous stream 0.05 M Pb(C₂H₃O₂)₂ at 294 K, followed by vacuum dehydration at 1 × 10^?6 Torr and 693 K. Its structure was determined at 100 K, by X-ray diffraction techniques in the cubic space group Fd $ \overline{3} $ 3 ¯ m and was refined to the final error indices R ₁/wR ₂ = 0.0639/0.1323. About 53.5 Pbⁿ⁺ ions per unit cell occupy three different equipoints; 26 are at site I′, 19 are at site II, and the remaining 8.5 are at another site II. Three Pb⁴⁺ ions at some of the positions must have higher oxidation states due to elevated dehydration temperature; Pb(IIa) is supposed to coexist with Pb²⁺ and Pb⁴⁺ ions assuming the charge balance of the zeolite framework. A distorted Pb₄O₄ cube, alternating Pb²⁺ at Pb(I′) and O^2? at O(5), coordinates with four Pb²⁺ and/or Pb⁴⁺ ions through its oxygen atoms to give a [Pb ₄ ²⁺ O ₄ ^2? (Pb _16/19 ²⁺ Pb _3/19 ⁴⁺ )₄]^176/19+ cluster in 4.75 of eight sodalite cavities per unit cell in zeolite Y.     

Influence of inorganic and organic additives on the composition of the precipitate of synthetic hydroxylapatite and calcium oxalate monohydrate

Synthetic hydroxylapatites are prepared with additives, such as Mg²⁺, CO ₃ ^2? , and C₂O ₄ ^2? . An increase in the concentration of magnesium leads to the formation of struvite. In the Ca(NO₃)₂-(NH₄)HPO₄-Na₂CO₃-NH₄OH-H₂O system, an excess of carbonate ions leads to the formation of calcite. When the synthesis is performed using oxalate ions as additives, calcium oxalate does not form the inherent phase. Calcium oxalate monohydrate is synthesized with additives, such as CO ₃ ^2? , HPO ₄ ^2? , and SO ₄ ^2? ions and urea, glycine, and glutamic acid. X-ray powder diffraction analysis has revealed that the composition of the CaC₂O₄ · H₂O precipitate remains unchanged under these conditions and in the presence of the aforementioned additives.     

Composition and properties of coals from the Yurty coal occurrence

Coals from the Yurty coal occurrence were studied. It was found that the samples were brown non-coking coals with low sulfur contents (to 1%) and high yields of volatile substances (V ^daf to 53.4%). The high heat value of coals Q _s ^daf was 20.6–27.7 MJ/kg. The humic acid content varied from 5.45 to 77.62%. The mineral matter mainly consisted of kaolinite, α-quartz, and microcline. The concentration of toxic elements did not reach hazardous values.     

Mixed Micellar Properties and Related Interaction Parameters of Butanediyl-1,4-bis(dodecyl dimethyl ammonium bromide) Gemini Surfactant with Nonionic Amphiphiles

Mixed micellization of cationic gemini surfactant butanediyl-1,4-bis(dimethyldodecylammonium bromide) with nonionic surfactants (sorbitan esters, alcohols and phenol ethoxylates) and triblock copolymers has been studied tensiometrically. Various physicochemical parameters of the studied systems including ideal CMC values, experimental and ideal micellar compositions, interaction parameters, activity coefficients of the components, etc. have been evaluated by considering theoretical models of Clint, Rubingh, Rosen and Maeda. The experimental critical micelle concentration (CMC) values of the mixed micelles were lower than the CMC values of the individual components and showed a negative deviation from ideal CMC (CMC*) values. The analysis reveals that the mole fractions of gemini are lower compared to the nonionic surfactants/triblock polymers and the values of ΔG _m ^° , ΔG _ad ^° , G _min and ΔG _ex ^m show that the spontaneity of the studied mixed micelles relatively decreases as the content of the gemini in the bulk phase increases.     

Synthesis and Properties in Solution of Gaussian Homo Asymmetric Polysiloxanes with a Bulky Side Group

Ring opening polymerization (ROP) of 1,3,5-tri-n-hexyl,1,3,5-trimethylcyclotrisiloxane (D ₃ ^Hexa ) and 1,3,5-tri-n-heptyl,1,3,5-trimethylcyclotrisiloxane (D ₃ ^Hepta ) was promoted by acid-treated synthetic silica–alumina to obtain Gaussian homo asymmetric polysiloxanes. M_w was above 70?kg/mol, meaning that homo asymmetric bulky side-group polysiloxane chains with high molecular weight were obtained. The material was treated in an acidic medium to improve the contents of acid sites and successfully tested as an inorganic acidic catalyst for ROP of D ₃ ^Hexa and D ₃ ^Hepta cyclosiloxanes. The samples of poly(methylhexylsiloxane) (PMHS) and poly(methylheptylsiloxane) (PMHepS) obtained were structurally characterized mainly by ²⁹Si NMR. All the experimental values including the refractive index increment (dn/dc), the second virial coefficient (A₂), the square root of the mean square radius of gyration ( $ \langle {{\text{RMS}}_{\text{radius}}}^{ 2} \rangle^{ 1/ 2} $ ), the average molecular weight (M_w), the average molecular numeral (M_n), and the weight polydispersity (M_w/M_n) were obtained using a gel permeation chromatography/light scattering (GPC/LS) coupled system. The A₂ experimental value for the two polymers (between 4 and 6.5?×?10^?4?mol/mL?g²) indicated that toluene was a good solvent. In addition, PMHS and PMHepS $ \langle {{\text{RMS}}_{\text{radius}}}^{ 2} \rangle^{ 1/ 2} $ were greater than 30?nm, indicating that larger chains of high molecular weight were obtained.     

Properties of adsorbents prepared by the alkali activation of Aleksandriisk brown coal

Highly microporous adsorbents (micropore fraction of ～70%) were prepared by the alkali activation-thermolysis (800°C, 1 h) of brown coal (C ^daf = 70.4%) in the presence of potassium hydroxide at the KOH/coal weight ratio R _KOH ≤ 2.0 g/g. The dependences of the specific surface areas and adsorption capacities of the adsorbents for methylene blue (A_MB, mg/g), iodine (A_I, mg/g), and hydrogen (\(A_{H_2 } \), wt %) on R _KOH were determined. The adsorbents obtained at R _KOH ≥ 1.0 g/g exhibited developed specific surface areas and good adsorption characteristics (A_I = 1000–1200 mg/g, A_MB = 200–250 mg/g, and \(A_{H_2 } \) ≤ 3.16 wt % at 0.33 MPa). The high capacity for hydrogen allowed us to consider brown coal adsorbents as promising materials for use as hydrogen accumulators.     

New host–guest supramolecular coordination polymers based on [(Me3Sn)3Fe(CN)6]n with alkali metal iodides and their applications as electrode materials in batteries

The metal iodides reduce partially the host coordination polymer of the type $ ^{ 3}_{\infty } \left[ {\left( {{\text{Me}}_{ 3} {\text{Sn}}} \right)_{ 3} {\text{Fe}}\left( {\text{CN}} \right)_{ 6} } \right] $ , I, to give new host–guest supramolecular coordination polymers (SCP). The physical and chemical characteristics of the new products were studied by elemental analyses, X-ray powder diffraction, IR, UV/Vis, and solid state NMR spectra. The host–guest SCP are [M_x(Me₃Sn)₃Fe_(1–x)^IIIFe _x ^II (CN)₆]_n M = Li⁺·2H₂O, 1; Li⁺, 2; Na⁺, 3; K⁺, 4; Cu⁺, 5, [Li(Me₃Sn)₃Fe^II(CN)₆]_n, 6 and [(LiDEE)_0.9(Me₃Sn)₃Fe _o.1 ^III Fe _o.9 ^II (CN)₆]_n, 7. The stoichiometry and nature of the guest depend on the type of the metal iodide and the reaction conditions. The polymeric nature of these SCP is due to the presence of trigonal bipyramidal configured structure which bridges between the single d-transition metal ions. The host–guest SCP containing the Li ions have been tested as electrodes to construct four different lithium-ion batteries.