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Torrefaction techniques are often used to improve the properties of biomass fuels. This study developed a new detailed lumped model to investigate the reaction mechanism of rice husk (RH) and rice straw (RS) degradation during the torrefaction process. The validity of this model was confirmed by comparing it with the experimental result. The van Krevelen diagram and CHO index are obtained by the simulation. A new parameter (loss of O/loss of energy) was also defined to account for the energy efficiency of the torrefaction system. The calculation of the Chemkin model showed that 260 °C is relatively an optimum torrefaction temperature for rice husks, while for straw is 270 °C. Compared to rice husk, rice straw has a higher energy yield and more loss of oxygen after torrefaction. The simulation can provide information on the whole range of temperature, which makes up the experimental defects such as time consumption and high cost. Combining the van Krevelen diagram, CHO index and the new parameter (loss of O/loss of energy) could provide useful information that deepens the understanding of the biomass torrefaction process and the inherent connection between the different indexes. It is believed that the research result can provide some valuable insights and guidance for understanding and optimizing the torrefaction process. [ABSTRACT FROM AUTHOR]

Elementary flux modes (EFMs) are an important concept in metabolic pathway analysis and for the derivation of macroscopic dynamic models. However, the computation of elementary flux vectors is facing combinatorial explosion with the size of the metabolic network, which hinders widespread application. This study proposes a systematic elementary flux mode reduction procedure to derive reduced-order dynamic models starting from an initial set of EFMs either generated by complete enumeration or subset selection. The procedure proceeds in several steps, including geometric and optimization-based criteria. The methodology ends up with a macroscopic bioreaction scheme with a reaction number smaller than that of the measured species, and shows very satisfactory prediction results, as illustrated with data of batch cultures of CHO-320 cells. • Detailed metabolic networks can be used to generate macroscopic models. • A systematic procedure to reduce the number of elementary flux modes is proposed. • When EFMs enumeration becomes intractable, minimal generation algorithms are exploited. • The reduction procedure is modular with steps that can be activated or bypassed. • CHO batch cultures can be efficiently represented by a few elementary flux vectors. [ABSTRACT FROM AUTHOR]

Normal temperature catalytic ozonation is an effective method for the removal of volatile organic compounds (VOCs). A series of TiO2-supported noble metal catalysts were synthesized by a facile impregnation method. The as-prepared catalysts were evaluated for the catalytic oxidation of toluene. It was determined that the 1 wt%Pt/TiO2 exhibited outstanding performance that 65% conversion of toluene was achieved with the space velocity of 30,000 h−1 even at room temperature (25°C). The structure–activity relationship of various catalysts was investigated via BET, XRD, SEM, TEM as well as XPS. The results indicated that the uniform dispersion of Pt nanoparticles, abundant surface adsorbed oxygen species as well as the strong interaction between Pt and TiO2 favoured toluene degradation at normal temperature. Based on FT-IR, a simplified reaction scheme was proposed: toluene was first oxidized to benzoate species then alcohol species, ketones, carboxyl acids, which was finally degraded into CO2 and H2O. The low activation energy of 1 wt%Pt/TiO2 determined to be 47 kJ mol−1 also benefited for toluene degradation at ambient temperature. [ABSTRACT FROM AUTHOR]

[Display omitted] • Review AuPd nanoparticle oxidation catalysis, activation of oxygen. • Mechanistic description of pathways for H 2 O 2 synthesis from H 2 and O 2. • O 2 adsorption and dissociation pathways over pure and mixed AuPd particles. • DFT potential energy surfaces for O 2 hydrogenation and O 2 − protonation pathways. • Pathways' relevance to aqueous phase conditions for H 2 O 2 synthesis. Catalysts consisting of Au, Pd and their alloys have been shown to be active oxidation catalysts. These materials can use dioxygen or hydrogen peroxide as the oxidant with CO and activated organic molecules using O 2 (g) while more challenging cases, such as methane to partial oxygenates, relying on H 2 O 2. Although H 2 O 2 is a green oxidant, the incorporation of dioxygen greatly reduces overall cost and so there is an incentive to find new ways to reduce the reliance on H 2 O 2. In this study we use DFT calculations to discuss the direct synthesis of H 2 O 2 from H 2 (g) and O 2 (g) and use this understanding to identify the important surface species derived from dioxygen. We cover the adsorption of oxygen, hydrogen and water to model Au and Pd nanoclusters and the oxidation of the metals, since reduction of any oxides formed will consume H 2. We then turn to the production of a surface hydroperoxy species; the first step in the synthesis of H 2 O 2. This can occur via hydrogenation of O 2 (ads) with H 2 (ads) or via protonation of O 2 (ads) by solvent water. Both routes are found to be energetically reasonable, but the latter is likely to be favoured under experimental conditions. [ABSTRACT FROM AUTHOR]

The results of microstructural, X-ray diffraction, differential thermal, and electron microprobe analyses of Zr–ZrCo–ZrNi cast alloys were used to first construct the liquidus surface of the Zr–ZrCo–ZrNi system on the composition triangle. The liquidus surface was found to consist of four primary crystallization surfaces of the phases: a solid solution of β-Zr and phases based on ZrCo (δ) and ZrNi (δ2) compounds and a θ phase (continuous solid solutions between Zr2Co and Zr2Ni isostructural compounds of AlCu2 type). In crystallization of the alloys, an invariant four-phase transition equilibrium with participation of the liquid phase, L + δ ↔ δ2 + θ, was observed at 1025°C. The constitution of the quasibinary sections of the ZrCo–ZrNi and Zr2Co–Zr2Ni systems, showing a decrease in the solidus and liquidus temperatures of the alloys with increasing nickel content, determined the type of invariant equilibrium. The study of cast alloys confirmed that the phase based on Zr3Co (η) compound formed by peritectoid reaction. A scheme of reactions occurring in Zr–ZrCo–ZrNi alloys in the temperature range from crystallization to solid-state transformations associated with the peritectoid formation of the η -phase and with the martensitic transformation of β ↔ α zirconium was developed. Two vertical sections were constructed using data on phase equilibria in the Zr–Co and Zr–Ni boundary binary systems and data on equilibria on the solidus surface and at 900 and 800°C in the Zr–ZrCo–ZrNi ternary system. Data on the interaction of individual alloys in the system with hydrogen were obtained. Significant rates of absorption and release of hydrogen from the hydrides were observed above room temperature. [ABSTRACT FROM AUTHOR]

Phase equilibria at 900°C and the liquidus projection in the Ni-rich corner of the Cu-Ni-Ti ternary system were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), electron probe microanalysis (EPMA) and differential scanning calorimetry (DSC) on the annealed and as-cast alloys. For the isothermal section at 900 °C, the hightemperature ternary compound (τ5) reported in the literature was not observed but the corresponding low-temperature compound (τ6) was identified to be stable at this temperature. For the liquidus projection, the primary phase τ4 was experimentally determined for the first time, and the related solidification paths were identified through the experimental data on the as-cast alloys. One solid-state invariant reaction, NiTi + τ4 → τ1 + Ni3Ti at 1098.3°C and two ternary eutectic reactions, L → τ1 + τ4 + NiTi at 1126°C and L → τ1 + τ6 + fcc(Cu,Ni) at 1069.5°C were detected. Scheil reaction scheme was also presented accordingly. All obtained experimental results will provide reliable information for further thermodynamic optimization of the Cu-Ni-Ti ternary system.

We link continuum models of reaction-diffusion systems that exhibit diffusion-driven instability to constraints on the particle-scale interactions underpinning this instability. While innumerable biological, chemical and physical patterns have been studied through the lens of Alan Turing's reaction-diffusion pattern-forming mechanism, the connections between models of pattern formation and the nature of the particle interactions generating them have been relatively understudied in comparison with the substantial efforts that have been focused on understanding proposed continuum systems. To derive the necessary reactant combinations for the most parsimonious reaction schemes, we analyse the emergent continuum models in terms of possible generating elementary reaction schemes. This analysis results in the complete list of such schemes containing the fewest reactions; these are the simplest possible hypothetical mass-action models for a pattern-forming system of two interacting species.

BACKGROUND: The search for alternative sources of fuels is crucial for sustainable development now and in the near future. Biomass attracts much attention as an environmentally friendly, green and CO2‐neutral source of fuels. Hydrodeoxygenation (HDO) of fatty acid‐based feedstocks such as nonedible vegetable oil, waste cooking oil and animal fat is a versatile technology for producing efficient fuels. HDO schemes are often contradictory and have different numbers of stages. In the work reported, a highly active nickel phosphide catalyst was obtained and methyl palmitate (MP) HDO kinetic modelling was carried out to elucidate the HDO reaction scheme. RESULTS: The effect of reduction temperature (400–600 °C) on the catalytic properties of the catalyst in MP HDO was evaluated and the most active catalyst (after reduction at 450 °C) was used in the kinetic experiments. The experimental data were collected in a wide range of MP conversion. The reaction scheme of MP HDO was elucidated by means of mathematical modelling which was specified by successive consideration of the experimental results of HDO selectivities at low MP conversions (1–10%), additional experiments of alcohol HDO (dodecanol‐1 as an analogue for hexadecanol‐1) and analysis of gas‐phase products. CONCLUSIONS: In accordance with the results obtained, both hydrolysis of MP and hydrogenolysis of C&bond;OCH3 bond should be considered for describing the conversion of MP to intermediate compounds. This finding could explain the synergetic effect of acid and metal centres, which has been reported in the literature on aliphatic ester HDO, and justify the higher activity of bifunctional catalysts in this reaction. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Kinetic analysis of isobutylene synthesis from ethanol in the presence of a ZnO/ZrO2 catalyst synthesized by incipient wetness impregnation of zirconium hydroxide with zinc nitrate has been conducted. Analysis data have been used to determine primary, secondary, stable, and unstable products. The selectivity for the reaction products and the order of their formation have been determined. A general scheme of the reaction routes for ethanol conversion to isobutylene has been proposed. [ABSTRACT FROM AUTHOR]

• A two-step parallel reaction scheme was established by analyzing |DDTG| curve. • A "shape index" is employed to estimate the value of reaction order. • Shuffled Complex Evolution was used to optimize pyrolysis kinetic parameters. • The predicted values using optimized parameters match TG data very well. The study of hydrogen fuel cell vehicles is currently one of the popular research topics. However, a vital issue for hydrogen fuel cell vehicles is the hydrogen tank safety when hydrogen tank catch fires. In this paper, the carbon fibre-epoxy composite from hydrogen tank was investigated by thermogravimetric analysis. Thermogravimetric experiments were carried out at three heating rates (20, 30 and 40 K/min) in a nitrogen atmosphere. A two-step parallel reaction scheme was developed for the decomposition of the carbon-fibre epoxy composite based on the K-K method and previous studies. The kinetic reaction scheme was coupled to Shuffled Complex Evolution (SCE) method to obtain optimized kinetic parameters. The predicted values using the optimized kinetic parameters show a good agreement with the experimental data, which shows the potential promising application of the reaction scheme and optimized kinetic parameters of the carbon-fibre epoxy composite. [ABSTRACT FROM AUTHOR]

Highlights • Coal char mixed with iron powder reduces NO and produces CO at medium temperature. • Higher oxygen concentration could promote both NO reduction and CO production. • Reaction mechanism was proposed based experimental results. Abstract NO reduction by CO in a rotary reactor, separating NO adsorption and reduction processes in two different zones, was demonstrated by our group in previous studies. As an indispensable part of this system, it's necessary to further reduce the residue NOx at the outlet of reduction zone and supply fresh reducing gas CO for this reactor. The aim of this paper is to look for some cheap materials to meet both aims and investigate the corresponding reaction mechanism. Coal char was chosen for this purpose since it could serve as both reducing agent and catalyst of NO reduction, and could also be the source of CO production. For some cases, simple iron powder was also physically mixed which coal char, expecting to enhance the reaction rates of NO reduction. Some key factors were investigated for their influence of target reactions, such as temperature, oxygen concentration, CO concentration, and presence of H 2 O and SO 2. Experimental results showed that mixed iron powder could effectively serve as catalyst for NO reduction, lowering the required reaction temperature. Higher oxygen concentration could promote both NO reduction and CO production. Both coal char and produced CO act as the reducing agent of NO reduction. In order to explore the reaction mechanism, various tests were carried out for samples and reactions under different conditions, such as SEM, TG, XPS and in situ DRIFT. SEM images illustrated that coal char is sintered in the absence of oxygen at high temperatures, but Fe could inhibit this sintering process. TG tests showed that reaction rate of coal char is the fastest in the presence of oxygen, and iron powder would inhibit the weight loss rate. XPS results displayed that both elevated temperatures and the addition of iron species could increase surface oxygen content. In situ DRIFT spectra revealed that the introduction of NO formed various nitrates on the surface of the coal char. Based on the experimental results and characterizations, reaction mechanism over coal char with/without mixed iron powder was proposed. [ABSTRACT FROM AUTHOR]

Lithium containing intermetallic alloys have recently become the focus of many investigations regarding their potential application as electrode materials for lithium ion batteries. However the overwhelming increase in volume during lithiation prohibits a general use of these materials in state of the art batteries. The Cu-Li-Sb system has gained much attention in this respect, as the intermetallic compound η-Cu 2 Sb showed remarkable cycling stabilities combined with a high charge capacity. To fully understand the reactions taking place upon charging/discharging of this material, a reliable phase diagram of the system is a prerequisite. Nevertheless almost no such data is available for the Cu-Li-Sb system. Especially reactions taking place at elevated temperatures become relevant regarding system malfunctions like e.g., thermal runaways of the battery cells. Therefore a substantial experimental investigation was conducted to enable the construction of three isothermal sections at 573 K, 673 K and 873 K. 83 alloy samples were thus metallurgically prepared and annealed at different temperatures. Analysis was done by powder X-ray diffraction. To validate the phase descriptions obtained from this data, electrochemical measurements were conducted. Coulometric titrations with four different Cu-Sb alloys (Cu concentrations = 80 at.%, 67 at.%, 50 at.%, 33 at.%) showed a good agreement with the phase fields expected from the powder X-ray diffraction data. 48 of the 83 samples were in addition analyzed by differential thermal analysis, which enabled the construction of two vertical sections (isopleths). These followed the lines connecting the binary alloy compositions Cu 66 Sb 34 and Cu 50 Sb 50 with Li. In addition a liquidus projection showing in- and mono-variant reactions, together with liquidus isopleths could be outlined. Finally a reaction scheme including all invariant reactions found within the system was developed. [ABSTRACT FROM AUTHOR]

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The whole C–Zr–Nb ternary system was assessed by means of CALPHAD method for the first time. All of the experimental phase diagram data available from the literature were critically reviewed and assessed using thermodynamic models for the Gibbs energies of individual phases. The solution phases including the liquid, fcc, hcp and bcc were described by the substitutional solution model. There is no ternary compound in this system. A set of self-consistent thermodynamic parameters for the C–Zr–Nb system is obtained. Comparisons between the calculated and measured diagrams show that the present thermodynamic description can account for the experimental information satisfactorily. The liquidus projection and reaction scheme for the C–Zr–Nb system were generated by using the present thermodynamic parameters. The effect of microstructure on the mechanical properties of C–Zr–Nb alloys homogenized at 1800 °C reported in the literature was discussed from a phase diagram point of view. [ABSTRACT FROM AUTHOR]

Abstract: The oxidation state of the active metal is an important factor for catalyst stability under dry and steam reforming conditions. This work explores the correlation of the oxidation state of the active metal with the coking behavior of alumina‐supported cobalt and nickel catalysts from a thermodynamic point of view. To this end, the thermodynamics of the oxidation of Co/γ‐Al2O3 and Ni/γ‐Al2O3 were investigated by using calculations at both standard and technical reforming conditions. It is shown that oxidation of nickel by water or CO2 cannot occur spontaneously under reforming conditions regardless of participation of the alumina support material because of the positive Gibbs reaction energies. Cobalt, in contrast, is more easily oxidized and may form CoAl2O4 through interaction with the support. This phase may react with surface carbon to regenerate the catalyst after carbon formation through thermal cracking of methane. A Mars–van Krevelen type reaction scheme is proposed to explain the higher coking resistance of cobalt compared to nickel. [ABSTRACT FROM AUTHOR]

A reaction scheme has been proposed for the oxidative steam reforming (OSR) of raw bio-oil on a Rh/CeO 2 -ZrO 2 catalyst, based on the study of the effect reaction conditions (temperature, space time, oxygen/carbon ratio and steam/carbon ratio) have on product yields (H 2 , CO, CO 2 , CH 4 , hydrocarbons). The runs were performed in a two-step system, with separation of pyrolytic lignin (first step) followed by catalytic reforming in a fluidized bed reactor (second step), under a wide range of reaction conditions (600–750 °C; space time, 0.15–0.6 g catalyst h/g bio-oil ; oxygen to carbon molar ratio (O/C), 0–0.67; steam to carbon molar ratio (S/C), 3–9). The catalyst is very active for bio-oil reforming, and produces high H 2 yield (between 0.57 and 0.92), with low CO yield (0.035–0.175) and CH 4 yield (below 0.045) and insignificant light hydrocarbons formation. The proposed reaction scheme considers the catalyzed reactions (reforming, water gas shift (WGS) and combustion) and the thermal routes (decomposition/cracking and combustion). The deactivation of the catalyst affects progressively the reactions in the following order: CH 4 reforming, hydrocarbons reforming, oxygenates reforming, combustion and WGS. [ABSTRACT FROM AUTHOR]

NiO layers were deposited by metal-organic chemical vapor deposition using bis-(ethylcyclopentadienyl) nickel (EtCp)Ni and oxygen or ozone. As a continuation of kinetic study of NiO MOCVD the gas-phase, transformations of (EtCp)Ni were studied in the temperature range of 380-830 K. Time of reactions corresponding to the residence time of the gas stream in hot zone of the reactor was about 0.1 s under conditions studied. The interaction of (EtCp)Ni with oxygen started at 450 K and its conversion rate reached the maximum at 700 K. The interaction of (EtCp)Ni with ozone started at 400 K and its conversion rate reached the maximum at 600 K. Transformations of the gas phase with the temperature in the reaction zone were studied, the model reaction schemes illustrating (EtCp)Ni transformations in the reaction systems containing oxygen and ozone have developed. In the reaction system (EtCp)Ni-O-Ar the main gas-phase products at 380-500 K were CO, CO, HCO, CHOH, CpCOOH, and CpO. Formation of the CHO, CHO, and CHO was found at 630-830 K. The same gas-phase species, (CHO)Ni and dialdehydes was formed in the reaction system (EtCp)Ni-O-O-Ar. [ABSTRACT FROM AUTHOR]

Detailed reaction schemes and experimental data for the online release of pyrolysis volatiles are required to gain a more fundamental understanding of biomass pyrolysis, which would in turn allow the process to be controlled in a more precise way and the development of more targeted applications. A detailed online characterisation of pyrolysis products has been conducted in single particle experiments with spruce pellets at different temperatures, obtaining a good closure of the elemental mass balances. The yields and online release of CO, CO 2 , H 2 O, CH 4 , other light hydrocarbons and total organic condensable species, as well as char yield and composition, can be predicted with a reasonable accuracy with the application of a single particle model, coupled with a detailed pyrolysis scheme, and a simple one-step scheme for tar cracking. In order to achieve it, improvements have been conducted in the pyrolysis scheme, mainly concerning the release of light hydrocarbons and char yield and composition. Deviations are still present in the different groups in which organic condensable species can be classified. [ABSTRACT FROM AUTHOR]

High pressure air injection (HPAI) has been proven as an enhanced oil recovery process in many fields. The reactions associated with crude oil and oxygen are the main difference between HPAI and other gas injection processes. In order to study the reaction schemes, different experiments, such as the combustion tube, kinetic cell, accelerating rate calorimeter, and thermogravimetry analysis, are conducted. In this paper, a reaction scheme is build that includes three classes of reactions: low-temperature oxidation, cracking, and combustion. We then use simulation models with the proposed reaction scheme included to history match the data from a combustion tube experiment and a kinetic cell experiment. It is demonstrated that the reaction scheme is valid. Based on this study, lumping the crude oil into four pseudocomponents brings a good matching result, and the kinetic parameters are obtained through matching the experimental results. [ABSTRACT FROM AUTHOR]

Some of hazardous liquid organic wastes, radioactive or not, are waiting from outlet to be destroyed. The ELIPSE process is a new technology of organic liquid destruction, involving a thermal plasma working under a water column, which ensures the cooling, the filtration and the scrubbing of the gases coming from the degradation. This study deals with the ability of the ELIPSE process to destroy the pure organic liquids and then to reduce the amount of organic matter remaining in the aqueous solution by means of the thermal or radiative properties of plasma. Preliminary test have shown how efficient the process is for the destruction of the organic liquids when they are directly fed in the plasma hearth. Extensive researches have been performed to assess the ability of the submerged plasma to destroy the remaining organic matters either by reinjecting them with the aqueous solution into the plasma or by using the UV ray coming from the plasma itself. A comparison of the experimental results obtained with various mechanisms proposed by the work carried out highlighted that this UV radiation could, by excitation of water molecules, produce radicals OH which may either dimerise to produce hydrogen peroxide H 2 O 2 , or react with organic substances present. The calculation of an activation energy of 8.5 ± 0.9 kJ mol −1 during the experiments shows that these radicals OH act directly after having been formed which explains a low H 2 O 2 content stability when the solution contains organic compounds. Thus, this photo-oxidation taking place in the water column could be used to improve the destruction of residual organic matter in the solution by maintaining the plasma after processing a given amount of organic liquids. [ABSTRACT FROM AUTHOR]