Ratio Of Reactants Research Articles

Effects of process parameters on preparation of Ti@SiO2 particles during fluidized bed chemical vapor deposition via design of experiments

Fluidized bed chemical vapor deposition (FBCVD) is a promising technology for preparing photocatalysts. However, the photocatalyst performance depends on numerous parameters, and the effects of process parameters on photocatalyst performance are not well understood. In this work, the effects of deposition time, fluidization number, reactant molar ratio and deposition temperature on photocatalysts prepared by FBCVD are investigated via a full factor factorial design approach, which is a kind of Design of Experiments. The results show that the deposition time, reactant molar ratio and deposition temperature are the main factors affecting the photocatalytic performance, while the fluidization number and the interactions between different parameters are insignificant factors. The characterization of the elemental content, elemental distribution and crystalline structure of Ti-deposited SiO2, Ti@SiO2, particles reveals that the formation of Ti-O-Si bonds and Ti-based nanoparticles on the Ti@SiO2 surface enhances the photocatalytic performance of the particles. Finally, the formation mechanisms of Ti@SiO2 particles are summarized which can be distinguished into two stages. At around 120 °C, intermediates such as Ti(OH)4 are generated and reactions consist of homogeneous and heterogeneous reactions. At around 400–600 ℃, the Ti@SiO2 particles are formed, which is dominated by heterogeneous reactions. The results of this study can improve understanding and control of photocatalyst preparation.

Amadori Reaction Products of Theanine and Glucose: Formation, Structure, and Analysis in Tea.

Amadori rearrangement products (ARPs) derived from the Maillard reaction between theanine and glucose (ARP 1), as well as pyroglutamic acid and glucose (ARP 2), were identified by liquid chromatograph tandem mass spectroscopy methods. The effects of initial reactant ratio, temperature, pH, and heating time on ARP generation were analyzed. The formation of both ARPs was most favored under 100 °C, while an alkaline environment slightly promoted the generation of ARP 1 and acidic conditions contributed more to ARP 2 formation. The decomposition of ARP 1 was suggested to be the predominant formation mechanism of ARP 2. Preparation, purification, and structure identification of ARP 1 were conducted, with its structure confirmed as 1-deoxy-1-l-theanino-d-fructose. The contents of ARP 1 in green, black, dark, white, yellow, and Oolong teas were quantitatively determined, of which black teas contained the highest levels of ARP 1, possibly due to the high glucose content and processing techniques.

Optimized scalable synthesis and granulation of MIL-88B(Fe) for efficient arsenate removal

Arsenic contamination has adverse health effects on human, and metal-organic frameworks (MOFs) are suitable adsorbents for its removal. The small-scale synthesis and high cost hindered the application of MOFs in arsenic removal. The challenge resulted from the strict synthesis conditions, like harsh temperature or pressure and the use of toxic organic solvents such as N, N-Dimethylformamide, etc. We reported herein an optimized method for scalable synthesis of MIL-88B(Fe) in innocuous ethanol solvent under benign conditions (low temperature, normal pressure, and no pretreatment of reactants). Synthetic parameters, such as the ratio of reactants, temperature, reaction time, and purification process, were optimized to achieve scalable preparation of the product. The scale-up produced MIL-88B(Fe) presents extraordinary adsorption capacity (128.99 mg/g) towards toxic arsenate in water. Furthermore, we shaped the MOFs powder into millimeter-scale granules by using the bio-compatible binding agents and flash freezing treatment. The composite also outperforms in arsenate adsorption capacity than that of commercially available products. Additionally, a 250-hours dynamic column adsorption operation proves that the composite can guarantee a safe concentration level of arsenate effluent. The well-shaped porous structure of composite facilitates its application and avoids secondary pollution in real scenarios, demonstrating applicable prospects as filters for water purification.

In situ synthesis of Al2O3–SiC powders via molten-salt-assisted aluminum/carbothermal reduction method

Al 2 O 3 –SiC composite powder (ASCP) was successfully synthesized using a novel molten-salt-assisted aluminum/carbothermal reduction (MS-ACTR) method with silica fume, aluminum powder, and carbon black as raw materials; NaCl–KCl was used as the molten salt medium. The effects of the synthesis temperature and salt-reactant ratio on the phase composition and microstructure were investigated. The results showed that the Al 2 O 3 –SiC content increased with an increase in molten salt temperature, and the salt–reactant ratio in the range of 1.5:1–2.5:1 had an impact on the fabrication of ASCP. The optimum condition for synthesizing ASCP from NaCl–KCl molten salt consisted of maintaining the temperature at 1573 K for 4 h. The chemical reaction thermodynamics and growth mechanism indicate that the molten salt plays an important role in the formation of SiC whiskers by following the vapor-solid growth mode in the MS-ACTR treatment. This study demonstrates that the addition of molten salt as a reaction medium is a promising approach for synthesizing high-melting-point composite powders at low temperatures.

Influence of solvent and salt on kinetics and equilibrium of esterification reactions

The influence of the solvent N-methyl-2-pyrrolidone (NMP) and the salt LiCl on the esterification of acetic acid (HAc) or propionic acid (HProp) with ethanol (EtOH) was investigated. Reaction kinetics were measured at T = 323 K and p = 1.01325 bar using in situ FTIR spectroscopy. Further, a thermodynamic activity-based kinetic approach was applied to predict the influences of NMP and LiCl on kinetics and equilibrium using ePC-SAFT advanced. The mole-fraction-based ‘intrinsic’ reaction-rate constants and the thermodynamic equilibrium constants were determined using the activity-based kinetic approach. These reaction constants allowed predicting the influences of the reactant ratio, NMP, and LiCl on homogeneity, reaction kinetics, and equilibrium in good agreement with the experimental data. The activity coefficients of the acid allowed understanding the experimental findings: they decreased upon NMP addition, which explains the slower reaction kinetics with NMP and they increased upon LiCl addition, which explains the faster kinetics with LiCl.

Effects of dual-inlet on premixed hydrogen/air combustion characteristics and thermal performance for micro thermophotovoltaic application

Premixed H2/air combustion in the micro-combustor with dual-inlet is investigated. Effects of the second-inlet settings on the combustion characteristics, thermal performance and radiation efficiency are discussed and compared. The results indicate that the second-inlet can efficiently modify burning characteristics and heat transmission, improving the burner thermal performance. With the increase of the distance between second-inlet and inlet, the mean outer wall temperature Tm is first risen and then down with a fixed reactants ratio of second-inlet Qin. It also affects the flow field and radiation temperature, and combustor C3 achieves the highest Tm 1180.9 K and radiation efficiency 28.231% at the total flow rate mf = 3.376 × 10−5 kg/s and Qin = 10%. For an augment of mf, the radiation temperature is improved while radiation efficiency is declined, and the combustor C2 obtains the highest radiation power 42.3 W at mf = 5.626 × 10−5 kg/s and Qin = 20%.

Ferric Chloride-Induced Synthesis of Silver Nanodisks with Considerable Activity for the Reduction of 4-Nitrophenol.

Silver nanodisks (AgNDs) have been successfully synthesized by using ferric chloride as an auxiliary agent in the presence of polyvinylpyrrolidone and N,N-dimethylformamide as both a solvent and a reducing agent. The mass ratio of reactants, temperature, and time were demonstrated to be the key factors determining the morphology of the product, and the conversion of Fe3+/Fe2+ ions played an important role in increasing the ratio of silver nanosheets (AgNSs). As the reaction prolonged, the etching effect of Cl– ions on the tips of AgNSs became more and more obvious, which made the obtained typical polygonal AgNSs turn into AgNDs eventually. In addition, the prepared AgNDs exhibited a considerable catalytic activity in the reduction of 4-nitrophenol.

Valorization of palm oil via cross-metathesis reaction using 1-octene

The use of palm oil-derived polyol in polyurethane manufacturing is restricted owing to its poor hydroxyl value, which results in a suboptimal polyurethane network. Palm oil could be first chemically modified by cross metathesis (CM) into olefin and ester products with terminal double bonds prior to converting it to the polyols with optimum hydroxyl value. Due to the catalyst degradation and the unwanted self-metathesis reaction, the plant oil CM employing ethylene has been limited by its poor selectivity and low yield. The goal of present research is to investigate the palm oil CM using 1-octene from the aspects of parametric and kinetic analysis. The use of 1-octene was hypothesized to prevent the formation of undesired catalytic intermediates and hence allowing the ruthenium-based Hoveyda Grubbs second generation catalyst (2nd HGC) to maintain its activity and stability. Adopting one factorial at time (OFAT) in a batch system, the effect of different parameters on cross-metathesis of palm oil was examined. The variation in reaction time, temperature, reactant molar ratio of 1-octene to triolein (MOC/TR), and catalyst loadings were correlated to triolein conversion, yield, and selectivity of 1-decene. The products such as 1-decene and glyceryl tri-9-decenoate were quantified using Gas Chromatography-Mass Spectrometry (GC-MS). The maximum triolein conversion and 1-decene yield, 97.78% and 293.36% respectively, were obtained when the cross metathesis of palm oil using 1-octene occurred at 343 K for 2 h with MOC/TR of 8 and catalyst loading of 5 ppm. After three consecutive catalytic tests carried out at best operating condition, the insignificant decline in the reaction performance evidenced that the 2nd HGC catalyst remained active and stable. It was also found that the power-law model well predicted the concentration profile of the cross-metathesis of palm oil using 1-octene, estimating activation energy of 22583 J/mol. This study developed a new technically feasible process for adding value to palm oil, by enabling the use of palm oil as a feedstock for the production of polyol.

Investigation of the Solution Chemistry of Hybrid Organic-Inorganic Indium Halides for New Material Discovery.

Recently, metal halide perovskites (MHPs) have emerged as a new class of materials for optical and electronic applications such as solar cells and ionizing radiation detectors. Although the solution-processability of MHPs is among their greatest advantages, the solution chemistries of most metal halide systems and their relationship with the observed structural and chemical diversity are poorly understood. In this work, we study the solution chemistry of a model indium halide system, methylammonium (MA)-In-Br, using a combination of the UV-vis spectroscopy, electrospray ionization mass spectrometry (ESI-MS) measurements, small-angle X-ray scattering (SAXS), and density functional theory (DFT) calculations. Our results show that indium could form either octahedral [InBr63-] or tetrahedral [InBr4-] anions in solution or a combination of both, depending on the loading ratios of MABr and InBr3 reactants. Understanding the solution chemistry of this system and recognizing the optical fingerprints of these polyanions allow for targeted crystallization of two novel compounds: MAInBr4 featuring tetrahedral [InBr4-] anions and MA2InBr5 containing both octahedral [InBr63-] and tetrahedral [InBr4-] anions. Further increase of the MABr content leads to the formation of previously reported MA4InBr7, containing only octahedral [InBr63-] anions separated by Br- anions. Our results suggest that understanding the solution chemistry of multinary metal halide systems could be a valuable tool for discovering functional materials for practical applications.

A Facile Total Synthesis of Kilogram-Scale Production of SKLB1039: A Novel and Selective Hexahydroisoquinolin-Containing EZH2 Inhibitor.

SKLB1039 is a potent, highly selective, and orally bioavailable EZH2 inhibitor, which significantly inhibited breast tumor growth and metastasis in pre-clinical studies. In a previously reported synthesis of SKLB1039, the yields of several steps were low, which led to an overall yield of less than 10%. In addition, flash chromatography was required for the purification of several intermediates using this route. To optimize the synthesis and establish an efficient commercial-scale method for the production of SKLB1039. The reaction time, solvent, reactant ratio, temperature, and mode of addition of reactants in the reductive amination, hydrolysis, hexahydroisoquinoline formation, hydrogenolysis, condensation and Suzuki crosscoupling reactions were optimized. A chromatography-free seven-step process starting from a commercially available material was developed that afforded SKLB1039 in 36% overall yield with > 99% purity. A cost-effective, high-yielding, and convergent kilo-scale synthesis for the EZH2 inhibitor SKLB1039 was developed. The operation was simple, and the pure product was easily obtained without column chromatography. This method will be economical and convenient for the subsequent industrial scale-up production of SKLB1039, which will be conducive for this promising EZH2 inhibitor to enter clinical studies of its antitumor effects.

Progress in the anhydrous production of oxymethylene ethers (OME) as a renewable diesel fuel in a liquid phase process

Oxymethylene ethers (OME) are a type of synthetic diesel fuel with particularly beneficial emission characteristics, caused by the presence of oxygen in the molecule. A production process based on renewables could therefore contribute to a sustainable solution for mobility. Within this study, synthesis of OME in an anhydrous liquid phase process based on dimethyl ether (DME) has been investigated. Employing various zeolites in a series of screening experiments, catalyst properties and activities have been investigated and thus, structure activity relationships could be identified, contributing to a better understanding of the process and enabling targeted catalyst development. Additionally, the influence of reaction temperature and reactant ratio has been assessed, which are crucial for an optimized OME production process.

Analysis of stack operating conditions for a polymer electrolyte membrane fuel cell

A polymer electrolyte membrane fuel cell is investigated in this study to assess its efficiency. In this regard, various operating conditions such as cell temperature, pressure, reactant/product flow rates and humidity affects are investigated analytically, and their interrelationships are discussed. The stack water management, mass transport phenomenon, ionic and electrical conductivity are also evaluated. The results are experimentally verified using a polymer electrolyte membrane fuel cell with an active surface area of 100 centimeters square. The membrane electrode assembly consists of Nafion® HP membrane. Also, AvCarb EP40 gas diffusion layers with 200 μm thicknesses are used. Results confirm that the overall stack efficiency can increase remarkably with the optimization of its operating parameters. The highest efficiencies are achieved around 100% humidity ratio of reactants at both cathode and anode. While high operating pressures improves individual cell efficiency, there are contradictory concerns at the stack level such as parasitic loads, losses, leakages and manufacturing costs.

Experimental Investigation on Two-Phase Rotating Detonation Fueled by Kerosene in a Hollow Directed Combustor

The operating characteristic of two-phase rotating detonation fueled by kerosene in a hollow combustor with the isolation section is experimentally studied. When the air mass flow rate is 1.5 kg/s, the equivalence ratio is 0.98, and the total temperature of the mixture is 650 K, the stable rotating detonation wave (RDW) is obtained, which verifies the feasibility of the designed two-phase rotating detonation combustor (RDC). It is found that there is a high-frequency oblique shock induced by the upstream rotating detonation wave in the isolation section. A series of experimental tests have been carried out by changing the total temperature of incoming air , which is an important factor affecting the initiation. When the equivalent ratio of reactants is between 0.950–1.152, a stable single-wave detonation is formed. With the increase of equivalent ratio, the time of detonation wave establishment decreases, the intensity and frequency of detonation wave increases, and the temperature of engine tail flame rises. The equivalent chamber pressure Δpφ was defined, and the curve of the performance of the RDC with the equivalent ratio was obtained. The velocity of the RDW increases with the increase of equivalent ratio, and the chamber pressure has an optimal value, a higher or lower equivalent ratio will lead to the decrease of equivalent chamber pressure and the combustion chamber performance.

A nano-liter droplet-based microfluidic reactor serves as continuous large-scale production of inorganic perovskite nanocrystals

Lead halide perovskite nanocrystals (NCs) exhibit high photoluminescence quantum yield (PLQY), high defect tolerance, narrow half peak width, and wide luminous gamut, making them the ideal optoelectronic materials in numerous fields. Nonetheless, their production still suffers from the limited productivity at the bench level. In this work, we fabricated CsPbX3 (X = Cl, Br, I) NCs within droplet-based micro-reactors, where both the nucleation and growth processes could be precisely controlled inside 130-nL microdroplets. This provides a new paradigm for the large-scale synthesis of perovskite NCs with high PLQY. Compared with other synthetic methods, this method can increase the concentration of reactant precursors by 3–116 times, while lowering the ligand to reactant ratio to 2%–50% of the commonly used hot-injection method. By modulating the reaction temperature and residence time, the structure-function relationship between the morphology of NCs and PL properties was extensively investigated. The microfluidic-based process allows the flexible adjustment in the proportion of PbX2 precursors to achieve the fabrication of perovskite NCs whose luminescence range covers the entire visible spectrum (406–677 nm) within one reaction. Finally, perovskite NCs with different halide ions were encapsulated in polymethyl methacrylate to prepare a colored light-emitting diode strip.

NO reduction mechanism in microreactor with cantor fractal structure

AbstractWith the rising emission of NO and particulate matter in vehicle exhaust, the atmosphere is gradually deteriorating and human health is being impacted. In order to reduce the NO emission in automobile exhaust devices, a tubular microreactor with a Cantor structure was studied in this paper. The NO conversion rate and concentration were evaluated by considering the fractal principle, reactant concentration ratio, inlet velocity and channel temperature. Increasing the fractal dimension could promote the mixing of reactants and make the distribution of species concentration in the channel more uniform. When the NO flux at the inlet of the microreactor channel was a constant, increasing the concentration of NH3 could significantly improve the reaction efficiency. Results show that the effect on the reaction results was best when the NO inlet velocity was lower and the NH3 inlet velocity higher. For example, when =0.025 m s−1 and =0.05 m s−1, the conversion rate of NO was as high as 98%. Porosity had little effect on the reaction results. Through comparison of the NO concentration at the outlet at different channel temperatures, it was concluded that increasing the temperature in the channel is most helpful in improving the reaction efficiency. © 2022 Society of Chemical Industry (SCI).

Rapid and selective on-site detection of triacetone triperoxide based on visual colorimetric method

In this work, a visual colorimetric method for the rapid and selective detection of triacetone triperoxide is reported. This visual colorimetric method is based on the reaction between potassium titanyl oxalate and hydrogen peroxide (H2O2) released from triacetone triperoxide degradation. Potassium titanyl oxalate can selectively react with H2O2 to form peroxo-titanic acid (an orange complex), enabling the colorimetric detection of triacetone triperoxide. Based on the theory that triacetone triperoxide produces hydrogen peroxide under acidic conditions, acid types, acid concentration, response time, visual limit of detection, and reactants ratio are systematically studied simultaneously for this colorimetric method. Under sulfuric acid concentration is 60%, the proposed method can almost detect triacetone triperoxide instantly, and the color of the solution reaches the maximum within 1 min and remains stable with a visual limit of detection as low as 3.0 × 10−5 mol/L. Interference experiments were carried out on other kinds of explosives (hexamethylene triperoxide diamine, trinitrotoluene, etc.). The use of colorimetric card brings great convenience to the rapid, qualitative, and semi-quantitative on-site detection of triacetone triperoxide. Because of its rapidity, high sensitivity, simplicity, and selectivity, the proposed visual colorimetric method can serve as a valuable and promising reference for triacetone triperoxide’s rapid, qualitative on-site detection.

Self-supported Co-Ni-S@CoNi-LDH electrode with a nanosheet-assembled core-shell structure for a high-performance supercapacitor

In this work, a nanosheet-assembled core-shell structure composite of Co-Ni-S@CoNi-LDH was prepared on Ni foam via hydrothermal synthesis, in which Co-Ni-S nanowires as cores were assembled with the shell of CoNi-LDH nanosheets. The combination of the high conductivity of Co-Ni-S, the high specific surface area of CoNi-LDH and the multivalent state of Ni and Co provided more active sites, short and effective ion transport paths, and great synergy, which played significant roles in the excellent performance of Co-Ni-S@CoNi-LDH. Meanwhile, the nanosheet-assembled core-shell structure improved the overall stability. Based on the characterisation and the performance measurements, the Co-Ni-S@CoNi-LDH electrode showed an excellent electrochemical performance. The Co-Ni-S@CoNi-LDH electrode acquired a specific capacitance of 2414 F/g at a 1 A/g current density and a high cycle stability with an 89.7% retention after 3000 cycles. The assembled hybrid supercapacitor Co-Ni-S@CoNi-LDH//AC delivered a high energy density of 59.11 Wh kg −1 at an 855.43 W kg −1 power density, as well as an excellent rate performance of 81% after 5000 cycles at a 5 A/g current density, showing good potential for practical applications. • Nanosheets are assembled oriented on the nanowires by hydrothermal synthesis. • The effects of the reactants ratio on the structure were investigated. • The Co-Ni-S@CoNi-LDH delivers a high gravimetric specific capacity of 2414 F/g. • Co-Ni-S@CoNi-LDH//AC device was assembled with excellent electrochemical performance.

Green diesel production from Karanja oil using mesoporous Ba(HPW12O40) solid acid catalyst

Highly mesoporous Ba(HPW12O40) heterogeneous acid catalysts were successfully synthesized by the two-step impregnation method and characterized for their catalytic activities, the trans-esterification reaction of Karanja oil was evaluated. The various amounts of catalyst were loaded in the acidic medium and then Barium salt of tungstophosphoric acid. The acid catalyst was characterized using a techniques like FT-IR, XRD, BET, TGA, SEM and EDX.The results indicate that Ba2+ was incorporated into the HPW12O40 framework via isomorphous substitution between Ba2+ ions. During the tests, it was observed that Ba (HPW12O40), for transerterification of pongamia oil (89%) at optimized reaction conditions of 120 °C, 16:1 methanol to reactant molar ratio, 0.75 wt% catalyst loading, and 3 hrs reaction time. The results show that all of the solids have catalytic activity in the cracking reaction, which lowers the ultimate acidity of the products. The solids also have catalytic activity in the transesterification of triglycerides, resulting in high ester yields of 95% from Pongamia oil. The biodiesel production from pongamia oils was characterized by FTIR analysis and 1H- NMR spectroscopy. With significant activity and stability, the used catalysts could be recycled up to three times.

New organic electrode materials for lithium batteries produced by condensation of cyclohexanehexone with p-phenylenediamine

The redox-active materials based on the condensation product of cyclohexanehexone with p-phenylenediamine (PTDA) were synthesized. The effect of the reactant ratios (1: n, n = 1, 2, 3) on the morphology and electrochemical properties of the resulting polymers PTDA1-PTDA3 was analyzed. In the case of PTDA3, a regular network crosslinked by CN-C bonds is formed resulting in a significant increase in the practical capacity of this material from 160 to 285 mAh g−1 corresponding to a three-electron redox process. Quantum-chemical modeling was performed to clarify the peculiarities of the lithiation mechanism. It is shown that the best sites for lithium cation coordination are adjacent oxygen and nitrogen atoms or two nitrogen atoms. For all polymer structures, sequential redox lithiation-delithiation processes have been established.

Bio-additives from glycerol acetylation with acetic acid: Chemical equilibrium model

In this work, the chemical equilibrium of glycerol (G) acetylation with acetic acid (AA) to form mono- (MAG), di- (DAG) and tri- (TAG) acetylglycerols has been studied. These compounds are biodegradable and renewable options as high-quality bio-additives to improve the antiknock properties and the viscosity of fuels and biofuels.Due to the absence of thermodynamic data, the physicochemical and thermodynamic properties of the compounds were determined, such as the specific heat, and the enthalpy and entropy of formation, by employing a second-order group-additivity predictive method. The values obtained were validated with few experimental data available in the literature (298 K, 101.325 kPa), showing differences in the range 0.2–8.9%.The compositions at equilibrium were calculated by minimizing the total Gibbs free energy of the system and considering the non-ideality of the liquid phase. For this purpose, different temperatures (350–500 K), reactant molar ratios (1–12) and initial water contents (0 and 40 wt%) were studied. The results revealed the global exothermicity of the system, showing that total glycerol conversion (∼100%) and high yields to TAG (>90%) can be achieved in the 350–500 K range by employing AA:G molar ratios between 9 and 12. As the presence of water in the glycerol solution produces a decrease of the glycerol conversion and selectivity to TAG, its removal from the reaction medium should be considered. A comparison between our results with the reported data based on different catalytic systems indicates that this model could successfully describe the chemical equilibrium of the system.