Alkali Ion Exchange Research Articles

Designing alkali-exchanged ZSM-5 catalysts for the dehydration of lactic acid to acrylic acid

This report shows that complete control of the degree of alkali exchange is possible by controlling the pH strength, and that is possible to distinguish the selectivity of the cations themselves in the lactic acid (LA) dehydration reaction by excluding undesired active sites arising from excess salts. We discovered that strong base conditions induced by alkali hydroxides (e.g., KOH) increase the degree of alkali ion exchange, and that in the absence of additional salts−such as halogen anions, oxides−the KOH-ZSM-5 catalyst exhibited high acrylic acid (AA) selectivity (∼70%) and durability (100 h). Characterization via temperature-programmed desorption (TPD) and pyridine-infrared (Py-IR) analysis revealed a full exchange of the protons bound to the Si–O–Al sites with potassium in commercial ZSM-5. In addition, structural pore expansion due to the desilication by KOH leads to significant enhancement in the selectivity for AA. The mechanistic impact of KOH treatment on lactic acid dehydration is also systematically verified by in situ IR spectroscopy.

The recycling and utilization of new energy batteries

As the main energy storage component of new energy vehicles, the retirement tide of power batteries is coming. The large-scale retirement of power batteries has brought huge benefits to the treatment of power batteries challenge. From the aspects of environment, resources and economy, the significance of power battery recycling is expounded, and the current status of power battery recycling is analyzed. It is aimed at strengthening new energy vehicles power battery recycling, from the aspects of improving laws and regulations, improving the recycling system and improving recycling technology, put forward countermeasures and suggestions. At present, the main technologies are mechanical separation technology, pyrolysis technology and wet extraction technology. Mechanical separation technology mainly uses vibration separation, eddy current separation and electrostatic separation methods to separate different substances in the battery. Pyrolysis technology refers to the heating of waste to a certain temperature in an oxygen-free or low-oxygen environment to decompose organic matter, gas, liquid and solid products. The pyrolysis technology method mainly recovers heavy metals such as nickel and zinc, and the recovery efficiency is high. However, air participation in the operation is easy to cause secondary pollution. Wet extraction technology mainly extracts valuable materials and valuable heavy metals through sorting and sorting, shelling, dissolving in acid and alkali solutions, extraction and ion exchange methods. This technology has a wide range of applications, high recycling rate and little impact on the environment, and is currently one of the mainstream technologies in the field of new energy vehicle battery recycling. However, the process is complex and lengthy, and the recovery of electrolyte and leaching residue is easy to cause secondary pollution, and the recovery cost is high.

An anionic MOF as a multifunctional platform for selective adsorption of CO2, separation of organic dyes and ionic conductivity

It is a very effective strategy to capture and separate carbon dioxide by incorporation of alkali cations into MOFs. Presented here is an anionic metal-organic framework (MOF) (Me2NH2)2Co(tpta)·2H2O (1), in which the exchange of alkali ions (Li+ and Na+) took place with H2N(Me)2+ cations. As expected, CO2/N2 selectivity of the framework was improved significantly and reached 61.6 due to the inclusion of Li + using the ideal adsorbed solution theory (IAST) model. The enhancement of its CO2 uptake capability and selectivity has been mainly attributed to the charge-quadrupole interaction. For the CO2/N2 system, it is found that the inclusion of Li+ rather than Na+ favors higher selectivity. Additionally, it successfully separated cationic dye crystal violet (CV+) from anionic dye methyl orange (MO−) by the column-chromatography. Evidently, the enhancement of the electrostatic interaction greatly improves the separation performance of the framework.

Diagnostics of highly charged plasmas with multicomponent 1+ ion injection.

We establish multicomponent 1+ injection into a charge breeder electron cyclotron resonance ion source and an associated computational procedure as a noninvasive probe of the electron density n_{e}, average electron energy 〈E_{e}〉, and the characteristic times of ionization, charge exchange, and ion confinement of stochastically heated, highly charged plasma. Multicomponent injection allows refining the n_{e}, 〈E_{e}〉 ranges, reducing experimental uncertainty. Na/K injection is presented as a demonstration. The 〈E_{e}〉 and n_{e} of a hydrogen discharge are found to be 600_{-300}^{+600}eV and 8_{-3}^{+8}×10^{11}cm^{-3}, respectively. The ionization, charge exchange, and confinement times of high charge state alkali ions are on the order of 1 ms-10 ms.

Connecting Thermodynamics of Alkali Ion Exchange on the Quartz (101) Surface with Density Functional Theory Calculations.

Periodic plane-wave density functional theory (DFT) calculations were performed on the α-quartz (SiO2) (101) surface to model exchange of adsorbed Li+ and either Na+, K+, or Rb+ in inner- and outer-sphere adsorbed, and aqueous configurations, which are charge-balanced with 2 Cl-. SiO- or SiOH groups represented the adsorption surface sites. The SiO- models included 58 H2O and 2 H3O+ molecules to approximate an aqueous environment, whereas the SiOH models had 59 H2O and 1 H3O+ molecules. The goal of this work is to calculate the heats of exchange for these alkali ions and to compare the results with those measured by flow microcalorimetry to ascertain the most probable mechanisms for these cations exchanging on the α-quartz (101) surface. Energy minimizations of each alkali ion adsorbed as outer-sphere complexes on SiOH surface sites, and as inner- and outer-sphere complexes on SiO- surface sites, were used to determine the energy of exchange (ΔEex) with Li+ for comparison with experimentally determined ΔHex values. Here, we present a novel method for calculating ΔEex using the difference in energies of geometry-optimized end member models. The aqueous and surface structures produced are similar to those observed experimentally. Although the trend for the calculated ΔEex values is consistent with those from the heats of exchange measured experimentally, the magnitude of our modeled ΔEex results is significantly larger than select experimental data from the literature [Peng, L. Zeta-Potentials and Enthalpy Changes in the Process of Electrostatic Self-Assembly of Cations on Silica Surface. Powder Technol. 2009, 193(1), 46-49]; we discuss the reasons for this discrepancy herein. The relative energy differences of the various configurations modeled have implications for the measurements of the surface charge via potentiometric titrations due to the more active role of alkali cations in quartz surface chemistry that have been previously considered as inert background electrolytes.

Catalytic and Mechanistic Insights into Side‐Chain Alkenylation of Toluene with Methanol for Styrene Formation

AbstractThe literature on catalytic and mechanistic aspects of the side‐chain alkenylation of toluene with methanol for the formation of styrene on solid base catalysts is reviewed. The development of catalysts and catalysis are described mostly on alkali ion exchange zeolite catalysts with fundamental chemistry related to the side‐chain alkenylation. Mechanistic studies performed from various viewpoints are described. Methods to elucidate the reaction mechanisms are discussed based on the identification of the adsorbed species of the reactants, use of plausible intermediate compounds as reactant, characterization of surface properties to examine the correlation with reaction results, poisoning of the active sites by certain molecules, and theoretical calculations of the energy profile along with the reaction coordinate. These studies are discussed with critical assessments. The review addresses several challenges that prevent the side‐chain alkenylation of toluene with methanol from industrialization which include decomposition of methanol to CO and H2, and co‐production of ethylbenzene. The paper covers mostly literature published during the period from 2000 to early 2021.

Anionic zinc(II) metal-organic framework post-synthetically modified by alkali-ion exchange: Synthesis, characterization and hydrogen adsorption properties

An anionic metal-organic framework with rutile topology was prepared and post-synthetically modified. DMA ions in the channels were exchanged by alkali ions (Li+, Na+, K+, Rb+ and Cs+) and prepared materials were characterized by elemental analysis, scanning electron microscopy, infrared spectroscopy, thermogravimetry and powder X-ray diffraction. The successful ion exchange process and the amount of ions exchanged were determined by ICP-MS measurements. The ion-exchanged samples were subsequently studied as gas adsorbents for hydrogen.

Fabrication and Properties of Polyimide/Aluminum Oxide Composite Films via Different Alkali Etching and Ion Exchange Technique

The polyimide (PI)/aluminum oxide (Al2O3) composite films were prepared via alkali surface modification and ion exchange technique on flexible PI films. Firstly, the polyamide acid layers were formed on both surfaces of PI film through chemical surface modification in aqueous KOH and NaOH solution, respectively. Subsequently the ion exchange process was processed in AlCl3 aqueous solution. After final thermal annealing in air, the aluminum ions which exchanged on both surfaces of PI film became continuous Al2O3 composite layers. The surface morphology, microstructures, thermal and electrical properties of the PI/Al2O3 composite films were tested by the scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), electric breakdown voltage and corona-resistant measurement. Results from SEM measuring revealed that the surfaces of composite films became much rougher with the increasing alkali treatment time. FT-IR spectrums showed that the treatments of alkali surface modification and ion exchange had no effect on molecular structure of polyimide. TGA results showed that the excellent thermal properties of the film are maintained. Electric breakdown voltage of composite films showed monotonically decreased with the increasing alkali treatment time. Corona-resistant test results showed that the best corona-resistant times of composite films which using NaOH and KOH modification were up to 22.6 minutes and 15.4 minutes, respectively.

Insights into the electrochemical Li/Na-exchange in layered LiCoO2 cathode material

The electrochemical alkali ion exchange is a powerful technique to synthesize novel active materials for secondary batteries or to study Li/Na/K analogous intercalation compounds. Herein, we report for the first time the electrochemically conducted exchange of Li-ions by Na-ions within the host lattice of LiCoO2. Li–Na substitution in a potential range of 2.0–4.0 ​V vs. Na/Na+ leads to the formation of a Li/Na-mixed intercalation compound. Operando XRD measurements and ex-situ EDS-mappings indicate that the different ionic radii and the corresponding CoO2-layer distances forbid Li–Na mixing in the lattice, resulting in the emergence of Na- and Li-rich domains during Na-ion insertion. Charging and discharging of the resulting Li/Na-mixed intercalation compound is dominated by Na-insertion and extraction, while Li-ions remain in the lattice until it is completely depleted of Na-ions. These novel insights concerning competitive kinetics, thermodynamics and phase evolution behavior can be highly useful to understand similarities and differences of Na- and Li-insertion chemistries to develop materials for future Na-ion batteries based on the comprehensive scientific knowledge in Li-ion technology.

Butcher Ridge igneous complex: A glassy layered silicic magma distribution center in the Ferrar large igneous province, Antarctica

Abstract The Butcher Ridge igneous complex, Antarctica, is an ∼6000 km3 hypabyssal silicic intrusion containing rhythmically layered glassy rocks. Baddeleyite U-Pb geochronologic analysis on a sample of the Butcher Ridge igneous complex yielded an age of ca. 182.4 Ma, which confirms that it was emplaced synchronously with the Ferrar large igneous province. Rocks of the Butcher Ridge igneous complex vary from basaltic andesite to rhyolite, and so the inferred volume of the Butcher Ridge igneous complex makes it the most voluminous silicic component of the Ferrar large igneous province. Major-element, trace-element, and isotopic data combined with binary mixing, assimilation-fractional crystallization (AFC), and energy-constrained AFC models are consistent with formation of Butcher Ridge igneous complex silicic rocks by contamination of mafic Ferrar parental magma(s) with local Paleozoic plutonic basement rocks. Field and petrographic observations and evidence for alkali ion exchange suggest that the kilometer-long, meter-thick enigmatic rhythmic layering formed as a result of secondary hydration and devitrification of volcanic glass along parallel fracture networks. The regularity and scale of fracturing/layering imply a thermally driven process that occurred during shallow emplacement and supercooling of the intrusion in the upper crust. We suggest that layering observed in the Butcher Ridge igneous complex is analogous to that reported from terrestrial and Martian cryptodomes, and therefore it is an ideal locality at which to study layering processes in igneous bodies.

Improving the pore-ion size compatibility between poly(ionic liquid)-derived carbons and high-voltage electrolytes for high energy-power supercapacitors

Maximizing carbon capacitance in high-voltage electrolytes has gained increasing interests to resolve the low energy storage concern in supercapacitors. Yet the large ion sizes and high viscosity of such electrolytes greatly thwart their compatibility with the pore diameters of carbon electrodes, leading to sluggish charge transport and unsatisfied energy-power outputs. Herein, heteroatom-doped, hierarchical porous carbons are derived from a high-carbon-yield main-chain poly(ionic liquid) bearing NH2+: HSO4− ion pairs and rigid aromatic backbones, followed by tailoring the 3D porous architecture through alkali ion exchange and in-situ activation. The typical sample (PIL-RbC) has sheet-like geometry, electron-rich N/O heterogeneous dopants, and a vast adsorbing surface (3021 m2 g−1). More importantly, PIL-RbC with ion-matching pores (dominated at 0.80 nm) and ion-transport paths (>1 nm pores) shows a superb compatibility with 1-ethyl-3-methylimidazolium tetrafluoroborate ionic liquid electrolyte, giving a maximized electrode capacitance of 228 F g−1 in a symmetric supercapacitor. The PIL-RbC-based device delivers a high energy density up to 119.4 Wh kg−1 at 397 W kg−1, and maintains 41.7 Wh kg−1 at a high power-output of 19.7 kW kg−1, along with a satisfactory tolerability (91% retention after 10,000 consecutive cycles at 4 V). This strategy sheds light on both synthesizing poly(ionic liquid)-derived heteroatom-doped porous carbons and matching well-designed carbon electrodes with high-potential electrolytes for integrated enhancements in supercapacitor performances.

Upgrading of heavy oil by thermal treatment in the presence of alkali-treated Fe/ZSM-5, glycerol, and biomass

Catalytic upgrading heavy oil as one of the important in-situ upgrading technologies has attracted worldwide interest for exploitation. Therefore, alkali-treated Fe/ZSM-5 catalyst for upgrading heavy oil was prepared by alkali treatment and ion exchange. 0.4 wt% alkali-treated Fe/ZSM-5, 1 wt% biomass, and 5 wt% glycerol were added into heavy oil (22,300 mPa·s measured at 50 °C) for reaction at 310–370 °C at 10 °C step size for 30 min. Compared with pyrolysis reaction under the same condition, the optimal viscosity reduction was increased by 81% at 350 °C. Physical properties of the catalysts before and after treatments were characterized by BET, ICP, XRD, Pyridine-IR. Besides, the structures and the group compositions of heavy oil samples before and after reactions at 350 °C were analyzed by SARA, FT-IR, EL, 1H NMR, GC–MS. It was found that alkali-treated Fe/ZSM-5 with larger specific area, larger amount of Bronsted acid sites, larger total pore volume, and larger average pore diameter compared with Na/ZSM-5 could have a positive impact on the upgrading heavy oil. Furthermore, it could be concluded that the reduction of its viscosity was mainly caused by the severely destroyed structure of resin in the process of the reaction. Meanwhile, the synergistic effect of alkali-treated Fe/ZSM-5 with glycerol and biomass was proposed and confirmed in this paper.

Communication: First-principles evaluation of alkali ion adsorption and ion exchange in pure silica LTA zeolite.

Using first-principles calculations, we studied the adsorption of alkali ions in pure silica Linde Type A (LTA) zeolite. The probability of adsorbing alkali ions from solution and the driving force for ion exchange between Na+ and other alkali ions at the different adsorption sites were analyzed. From the calculated ion exchange isotherms, we show that it is possible to exchange Na+ with K+ and Rb+ in water, but that is not the case for systems in a vacuum. We also demonstrate that a solvation model should be used for the accurate representation of ion exchange in an LTA and that dispersion interactions should be introduced with care.

Research on pavement performance of mixed filler with alkaline residue-expansive soil

The expansive soil, a special clay, can cause crack, bulge, landslides and other accidents in the highway subgrade. To reduce the harm of expansive soil and realize the resource utilization of alkaline residue which is industrial solid waste, different ratio of alkaline residue and expansive soil with medium expansive potential are mixed as subgrade filling. A series of experiments are carried out for the pavement performance of the mixture. The results show that the swelling ratio of the mixture decreases significantly with the mixing rate. The longer the curing time is, the lower the swelling ratio will be. And the expansibility is completely eliminated in 28 days. The unconfined compressive strength(UCS) heightens with the growth of mixing rate, and when the mixing rate reaches 30%, the increasing level gradually stabilizes. Similarly, the curing time has an obvious effect on the unconfined compressive strength. After cured for 14 days, the UCS of samples is twice of that not cured. And the cohesion goes up in first stage, then decreases, and peaked as the mixing rate reaches to 30%. However, the internal friction angle changes little. The CBR increases with the increase of mixture ratio and the curing time. In addition, the mechanism of alkali residue modifying curing expansive soil is mainly based on the substitution effect of alkali residue, coagulation reaction and ion exchange of alkali residue - expansive soil.

Immobilization of LiCl-Li2O pyroprocessing salt wastes in chlorosodalite using glass-bonded hydrothermal and salt-occlusion methods

In this study, hydrothermal and salt-occlusion processes were used to make chlorosodalite through reactions with a high-LiCl salt simulating a waste stream generated from pyrochemical treatment of oxide-based used nuclear fuel. Some products were reacted with glass binders to increase chlorosodalite yield through alkali ion exchange and to aid in densification. Hydrothermal processes included reaction of the salt simulant in an autoclave with either zeolite 4A or sodium aluminate and colloidal silica. Chlorosodalite yields in the crystalline products were nearly complete in the glass-bonded materials at values of 100 mass% for the salt-occlusion method, up to 99.0 mass% for the hydrothermal synthesis with zeolite 4A, and up to 96 mass% for the hydrothermal synthesis with sodium aluminate and colloidal silica. These results show promise for using chemically stable chlorosodalite to immobilize oxide reduction salt wastes.

Calorimetric Study of Alkali Metal Ion (K+, Na+, Li+) Exchange in a Clay-Like MXene

Intercalation of ions in layered materials has been explored to improve the rate capability in Li-ion batteries and supercapacitors. This work investigates the energetics of alkali ion exchange in a clay-like MXene, Ti3C2Tx, where Tx stands for anionic surface moieties, by immersion calorimetry in aqueous solutions. The measured immersion enthalpies of clay-like Ti3C2Tx, ΔHimm, at 25 °C in 1 M KCl, 1 M NaCl, 1 M LiCl, and nanopure water are −9.19 (±0.56), −5.90 (±0.31), −1.31 (±0.20), and −1.29 (±0.13) kJ/mol of MXene, respectively. Inductively coupled plasma mass spectrometry is used to obtain the concentrations of alkali ions in the solid and aqueous phases. Using these concentrations, the enthalpies of exchange of alkali metal ions (Li+, Na+, and K+) are calculated; ΔHex in 1 M KCl, 1 M NaCl, 1 M LiCl, and nanopure water are −9.3 (±2.2), 21.0 (±0.9), −1.3 (±0.2), and 302.4 (±0.6) kJ/mol of MXene, respectively. Both immersion and exchange enthalpies are most exothermic for potassium. This suggests that ...

Cell responses on a H2Ti3O7nanowire film

Cell morphologies on H2Ti3O7nanowire film and anatase nanowire film.

Compositionally Enhanced Flexibility in a Ga-Rich Zeolite Affords Unusual Structural Changes via Alkali Ion Exchange

Compositionally Enhanced Flexibility in a Ga-Rich Zeolite Affords Unusual Structural Changes via Alkali Ion Exchange

Hierarchical FAU‐ and LTA‐Type Zeolites by Post‐Synthetic Design: A New Generation of Highly Efficient Base Catalysts

AbstractHierarchical FAU‐ and LTA‐type catalysts are prepared by post‐synthetic modifications and evaluated in the base‐catalyzed Knoevenagel condensation of benzaldehyde with malononitrile. A novel route to attain mesoporous Al‐rich zeolites (A and X) is demonstrated, while mesoporous Y and USY zeolites are prepared using recently developed methods. Base functionality is introduced by alkali ion exchange (Cs, Na) or by high‐temperature nitridation in ammonia. A thorough characterization of the zeolites' structure, composition, porosity, morphology, and basicity demonstrates that the presence of a secondary mesopore network enhances the ion‐exchange efficiency and the structural incorporation of nitrogen. The modified USY zeolites display twice the conversion, while the hierarchical A, X, and Y are up to 10 times more active based on the enhanced accessibility. These results demonstrate that the Knoevenagel condensation takes place predominately at the external surface, highlighting secondary porosity as a key criterion in the design of basic zeolite catalysts.

Preparation of Polyimide/Zinc Oxide Nanocomposite Films via an Ion-Exchange Technique and Their Photoluminescence Properties

Polyimide (PI) composite films with ZnO nanoparticles embedded in the surface layer were prepared by alkali hydrolyzation following ion exchange in Zn(NO3)2solution and thermal treatment of the zinc ion-doped PI films in air atmosphere. The effect of alkali treatment, ion exchange, and thermal treatment conditions was investigated in relation to the amount of zinc atomic loading, morphology, photoluminescence (PL), and thermal properties of the PI/ZnO composite films using ICP, XPS, FE-SEM, TEM, Raman microscope, TGA, and DSC. ZnO nanoparticles were formed slowly and dispersed uniformly in the surface-modified layers of PI films with an average diameter of 20 nm. The PL spectra of all the PI/ZnO nanocomposite films obtained at 350°C/7 h possessed a weak ultraviolet emission peak and a broad and strong visible emission band. The PI/ZnO nanocomposite films maintained the excellent thermal property of the host PI films.