Project description:Abstract The two ionic compounds [Ph4P][NTf2] and Cs[NTf2] were qualified to be suitable liquid materials for different high temperature applications. Development and optimization of these application techniques require knowledge of the thermodynamic properties of vaporization. Vapor pressures and vaporization enthalpies have been measured by using quartz?crystal microbalance. Solubility parameters and miscibility of ionic liquids in practically relevant solvents were assessed. The volatility of ionic liquids is not negligible at elevated temperatures. It is related to vapor pressures. We report the precise absolute vapor pressures and enthalpies of vaporization, of [Ph4P][NTf2] and Cs[NTf2], which were measured using the quartz?crystal microbalance (QCM) method. Volatilities of both compounds is significantly lower compared to commonly used [Cnmim][NTf2] These values are useful for catalytic applications of ionic liquid as well as for qualitative assessment solubilities of ionic compounds in common ionic liquids of practical importance.
Project description:Molten salts are crucial materials in energy applications, such as batteries, thermal energy storage systems or concentrated solar power plants. Still, the determination and interpretation of basic physico-chemical properties like ionic conductivity, mobilities and transference numbers cause debate. Here, we explore a method for determination of ionic electrical mobilities based on non-equilibrium computer simulations. Partial conductivities are then determined as a function of system composition and temperature from simulations of molten LiFαClβIγ (with α + β + γ = 1). High conductivity does not necessarily coincide with high Li+ mobility for molten LiFαClβIγ systems at a given temperature. In salt mixtures, the lighter anions on average drift along with Li+ towards the negative electrode when applying an electric field and only the heavier anions move towards the positive electrode. In conclusion, the microscopic origin of conductivity in molten salts is unraveled here based on accurate ionic electrical mobilities and an analysis of the local structure and kinetics of the materials.
Project description:Current environmental concerns have led to a search of more environmentally friendly manufacturing methods; thus, natural fibers have gained attention in the 3D printing industry to be used as bio-filters along with thermoplastics. The utilization of natural fibers is very convenient as they are easily available, cost-effective, eco-friendly, and biodegradable. Using natural fibers rather than synthetic fibers in the production of the 3D printing filaments will reduce gas emissions associated with the production of the synthetic fibers that would add to the current pollution problem. As a matter of fact, natural fibers have a reinforcing effect on plastics. This review analyzes how the properties of the different polymers vary when natural fibers processed to produce filaments for 3D Printing are added. The results of using natural fibers for 3D Printing are presented in this study and appeared to be satisfactory, while a few studies have reported some issues.
Project description:Elemental white phosphorus (P4) is a key feedstock for the entire phosphorus-derived chemicals industry, spanning everything from herbicides to food additives. The electrochemical reduction of phosphate salts could enable the sustainable production of P4; however, such electrosynthesis requires the cleavage of strong, inert P-O bonds. By analogy to the promotion of bond activation in aqueous electrolytes with high proton activity (Brønsted-Lowry acidity), we show that low oxide anion activity (Lux-Flood acidity) enhances P-O bond activation in molten salt electrolytes. We develop electroanalytical tools to quantify the oxide dependence of phosphate reduction, and find that Lux acidic phosphoryl anhydride linkages enable selective, high-efficiency electrosynthesis of P4 at a yield of 95% Faradaic efficiency. These fundamental studies provide a foundation that may enable the development of low-carbon alternatives to legacy carbothermal synthesis of P4.
Project description:Solar energy as an abundant renewable resource has been investigated for many years. Solar thermoelectric conversion technology, which converts solar energy into thermal energy and then into electricity, has been developed and implemented in many important fields. The operation of solar-thermal-electric conversion systems, however, is strongly affected by the intermittency of solar radiation, which requires installation of thermal storage subsystems. In this work, we demonstrated a new solar-thermal-electric conversion system that consists of a thermoelectric converter and a rapidly charging thermal storage subsystem. A magnetic-responsive solar-thermal mesh was used as the movable charging source to convert incident concentrated sunlight into high-temperature heat, which can induce solid-to-liquid phase transition of molten salts. Driven by the external magnetic field, the solar-thermal mesh can move together with the receding solid-liquid interface thus rapidly storing the harvested solar-thermal energy within the molten salts. By connecting with a thermoelectric generator, the harvested solar-thermal energy can be further converted into electricity with a solar-thermal-electric energy conversion efficiency up to 2.56%, and the converted electrical energy can simultaneously light up more than 40 orange-colored LEDs. In addition to stable operation under sunlight, the charged thermal storage subsystem can release the stored heat and thus enables the solar-thermal-electric system to continuously generate electricity after removal of solar illumination.
Project description:A rapid, simple procedure is described for synthesizing trialkyl, dialkylaryl, and alkyldiaryl sulfonium salts that features a selective extraction procedure to access analytically pure sulfonium salts. Alkylation of dialkylsulfides, alkylarylsulfides, and diarylsulfides followed by partitioning between acetonitrile and hexanes efficiently separates nonpolar reactants and byproducts, the usual impurities, to afford analytically pure crystalline and noncrystalline sulfonium salts. The method is efficient, general, and particularly well suited for the preparation of oily sulfonium salts that are otherwise extremely difficult to purify.
Project description:Being the only sustainable source of organic carbon, biomass is playing an ever-increasingly important role in our energy landscape. The conversion of renewable lignocellulosic biomass into liquid fuels is particularly attractive but extremely challenging due to the inertness and complexity of lignocellulose. Here we describe the direct hydrodeoxygenation of raw woods into liquid alkanes with mass yields up to 28.1 wt% over a multifunctional Pt/NbOPO4 catalyst in cyclohexane. The superior performance of this catalyst allows simultaneous conversion of cellulose, hemicellulose and, more significantly, lignin fractions in the wood sawdust into hexane, pentane and alkylcyclohexanes, respectively. Investigation on the molecular mechanism reveals that a synergistic effect between Pt, NbOx species and acidic sites promotes this highly efficient hydrodeoxygenation of bulk lignocellulose. No chemical pretreatment of the raw woody biomass or separation is required for this one-pot process, which opens a general and energy-efficient route for converting raw lignocellulose into valuable alkanes.
Project description:Torrefaction is a thermochemical pretreatment that enhances biomass properties, improving energy density, decomposition resistance, and hydrophobicity, making it a viable alternative as biofuel. This study performed a thermodynamic assessment of the torrefaction process for urban forest waste, integrating experimental data with two-step reaction kinetic modeling to evaluate the torrefaction product yields and properties using Aspen Plus software. The process was modeled with a yield reactor, employing the Peng-Robinson equation to describe vapor-phase behavior and empirical correlations to predict solid-phase properties. Simulations were validated against experimental data for temperatures between 225 and 275 °C, achieving an absolute deviation of less than 5%. Energy consumption ranged from 368 kJ·h-1 for light torrefaction to 1853 kJ·h-1 for severe torrefaction. Process irreversibility varied from 326 kJ·h-1 (3% exergy destruction) in light torrefaction to 3993 kJ·h-1 (16% exergy destruction) in severe torrefaction. The research provides a robust model for torrefaction scale-up that is adaptable to diverse biomass feedstocks and process conditions, highlighting its potential for optimizing energy use and improving sustainability in biomass utilization.
Project description:Resprouting multi-stemmed woody plants form an important component of the woody vegetation in many ecosystems, but a clear methodology for reliable measurement of their size and quick, non-destructive estimation of their woody biomass and carbon stock is lacking. Our goal was to find a minimum number of sprouts, i.e., the most easily obtainable, and sprout parameters that should be measured for accurate sprout biomass and carbon stock estimates. Using data for 5 common temperate woody species, we modelled carbon stock and sprout biomass as a function of an increasing number of sprouts in an interaction with different sprout parameters. The mean basal diameter of only two to five of the thickest sprouts and the basal diameter and DBH of the thickest sprouts per stump proved to be accurate estimators for the total sprout biomass of the individual resprouters and the populations of resprouters, respectively. Carbon stock estimates were strongly correlated with biomass estimates, but relative carbon content varied among species. Our study demonstrated that the size of the resprouters can be easily measured, and their biomass and carbon stock estimated; therefore, resprouters can be simply incorporated into studies of woody vegetation.
Project description:A novel purification process was proposed for molten salts based on the polarization of a hydrogen electrode on nickel, i.e., H+/H2, Ni electrode. The features of the H+/H2, Ni electrode in typical chloride and fluoride molten salts were investigated. Consistent current electrolysis was performed in a feasible polarization range, and the deoxidation efficiency was higher than that of the traditional chemical or electrochemical purification methods in both chloride and fluoride molten salts. Only H2 was used as a purification source gas, and almost no toxic HF or corrosive HCl emissions were used or occurred in the new process. The application range of the proposed method was also discussed.