Liquid Ion Exchange Method Research Articles

Hybrid exchange methods regulate Cu+ location on Cu-Y zeolites and improve CO adsorption capacity and selectivity

This work systematically examines the influence of preparation methods on the active Cu+ anchoring sites over FAU zeolites and their CO storage capacity and selectivity. The involved preparation methods here include individual liquid ion exchange method with CuCl2 solution, individual solid ion exchange method with CuCl powder and the hybrid exchange method. For the obtained Cu-Y samples, XRD, Ar adsorption/desorption at 87 K, TEM and NMR were used to characterize their skeleton structure, meanwhile, XPS and H2-TPR were utilized to identify the Cu+, Cu2+ and CuCl distribution. The CO storage capacity was implemented through CO adsorption–desorption isotherms. The correlation between various Cu species and CO storage capacity was analyzed and DFT calculation was employed to further elucidate the optimal Cu+ location induced by preparation methods. Finally, it is found that the isolated Cu+ is the dominating CO adsorption sites and Cu+ on site III present higher bonding energy with CO molecules. The hybrid preparation method seems the optimal choice for Cu-Y synthesis since the initial liquid ion exchange operation could prevent the framework corrosion from the subsequent solid ion exchange process, which benefits the optimal CO storage capacity and CO/N2 selectivity.

Extraction for Mo(VI), W(VI) and Mn(VII) as Oxyanions by Incorporation Cloud Point with Liquid Ion Exchange Methods

Highly sensitive method for separation and determination of micro amount of oxyanion for Mo(VI), W(VI), and Mn(VII) was performed. It has been done after formation of ion pair association complexes with Safranin as complexing agent including joint cloud point extraction with liquid ion exchange methods in the presence of non-ionic surfactant Triton X–100. The study is based on the values of wavelength of maximum absorbance, λmax= 536, 533, and 534nm respectively. Optimal conditions have been pinpointed high extraction efficiency needed for HCl concentration (1.0, 1.0 and 0.6) M respectively in the presence of 50µg metal ions in 10mL aqueous solutions. Besides, the stoichiometry of probable extracted structure of ion pair complexes was1:1:1 for all extracted complex, in addition to other effective parameters on extraction efficiency in this study.

Extraction and Preconcentration of Cd (II) by using Crown Ether DB18C6

Extracted Cd(II) as (CdCl3-) and (CdCl42-) from HCl media after preparing ion pair complexes according to liquid ion exchange method by using DB18C6 after changing to liquid ion exchanger K-Crown+; Cl-, spectrophotometric studies showed that the extracted ion pair complex had a wave length for maximum absorbance of λmax=277nm. Limitations to the study include optimum conditions for extraction in this study show a need for 0.3M HCl, to be present 50µg for Cd(II), in addition to study extracted complex structure by Slope ratio method, the result appear more probable structure of extracted complex [K DB18C6]+;HCdCl4- and [K-DB18C6]+; CdCl3-. This method applied to spectrophotometric determination of Cd(II) in different sample and compare the results with atomic absorption spectroscopy.

Synthesis and characterization of Ag-ion-exchanged zeolite/TiO2 nanocomposites for antibacterial applications and photocatalytic degradation of antibiotics

This paper investigates the synthesis, antibacterial, and photocatalytic properties of silver ion-exchanged natural zeolite/TiO2 photocatalyst nanocomposite. Zeolite is known to have a porous surface structure, making it an ideal substrate and framework in different nanocomposites. Moreover, natural zeolite has a superior thermal and chemical stability, with hardly any reactivity with chemicals. Finding an effective and low-cost method to remove both antibiotics and bacteria from water resources has become a vital global issue due to the worldwide excessive use of chemicals and antibiotics. This research aims to propose a facile method to synthesize Ag-ion-exchanged zeolite/TiO2 catalyst for anti-bacterial purposes and photocatalytic removal of atibiotics from wastewaters. TiO2 particles were deposited on the surface of natural zeolite. Ag ion exchanging was performed via a liquid ion-exchange method using 0.1 M AgNO3 solution. X-ray diffractometry (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and Fourier-transform infrared spectroscopy (FTIR) were used to evaluate the structure of synthesized powders. Antibacterial activities of samples were assessed, using Staphylococcus aureus ATCC 25923 and Escherichia coli ATCC 25922 by disc diffusion method. It was shown that Ag-containing nanocomposite samples have an improved antibacterial performance in both cases. Results showed that the synthesized catalyst has promising potentials in wastewater treatment.

Hybrid Cu-Fe/ZSM-5 Catalyst Prepared by Liquid Ion-Exchange for NOx Removal by NH3-SCR Process

A series of Cu/ZSM-5, Fe/ZSM-5, and Cu-Fe/ZSM-5 catalysts (Si/Al in ZSM-5 = 25) were prepared by different metal loadings using the liquid ion-exchange method. Several characterization methods were conducted to explore the effects of metals on the physical and chemical properties of catalysts. Meanwhile, the electron paramagnetic resonance method is also used to assess the copper and/or iron elements’ coordination and valence state at intersections or in channels of ZSM-5. The metal-loading effects of all catalysts on the catalytic activities were studied for the removal of NOx in a fixed-bed flow reactor using selective catalytic reduction with ammonia (NH3-SCR). The results showed that the iron’s addition could markedly broaden the operation temperature range of the Cu/ZSM-5 catalyst for NH3-SCR between 200 and 550°C due to the presence of more isolated Cu2+ ions as well as additional oligomeric Fe3+ active sites and FexOy oligomeric species. This paper gives a facile and straightforward way to synthesize the practical-promising catalyst applied in NH3-SCR technology to control NOx emissions.

Liquid ion exchange methodology for extraction Cr (VI) using azo derivative compound

Abstract 2-[(4-Carboxy methyl phenyl)azo]-4,5-di phenyl imidazole [4-CMePADPI] used for extraction chromium as CrO4−2 and Cr2O7−2 from aqueous solutions according to liquid ion exchange method after ion pair association formed, the procedure demonstrate concentration of HCl needed for formation liquid ion exchanger that give a high extraction efficiency with ligand is 0.2 M, for CrO4−2 and 0.3 M for extraction Cr2O7−2 in organic phase. Furthermore, the optimum pH for extraction the studied ions is pH = 10 for CrO4−2 and pH = 5 for Cr2O7−2 in aqueous phase. The shaking time necessary for extraction was 15 min for CrO4−2 and 10 min for Cr2O7−2. The optimal chromium concentration appears 40 μg/5ml and 30 μg/5ml for CrO4−2 and Cr2O7−2 respectively. The experiments also deduce that the favourable organic solvent for extraction is amyl alcohol without any effect for the polarity of organic solvents, as well as the results show that the anion exchange reaction was endothermic for both studied anions. In order to explain the mechanism of liquid ion exchange extraction and solubilization of the ion-association complex in the liquid–liquid extraction process, thermodynamic investigations have been carried out.

The synthesis of Cu/SAPO-34 catalysts and evaluation ability of NOx treatment by NH3-SCR with Cu/ZSM-5 catalyst using commercial ZSM-5 as support

SAPO-34 molecular sieves were synthesized under hydrothermal conditions using different combinations of tetraethyl ammonium hydroxide (TEAOH), morpholine (Mor), and triethylamine (TEA) as organic structure-directing agents and economical silicon source by colloidal silica LUDOX AS-30. The products were characterized by X-ray diffraction, Field Emission Scanning Electron Microscopes, Energy-dispersive X-ray spectroscopy, NH3 temperature - programmed desorption, N2 adsorption-desorption. Electron paramagnetic resonance technique was applied to identify isolated Cu2+ ions in the framework. Although materials with the same chabazite framework structure are obtained, they possess different physicochemical properties, especially crystal size and acidity. Catalytic performances of Cu/SAPO-34 and Cu/ZSM-5 using commercial ZSM-5 as support with the loading of 3 wt% prepared by liquid ion-exchange method was performed for selective catalytic reduction (SCR) of NOx with NH3.

Evaluation of Cu/SAPO-34 Catalysts Prepared by Solid-State and Liquid Ion-Exchange Methods for NO x Removal by NH3-SCR.

Cu/SAPO-34 catalysts are prepared using solid-state ion exchange (SSIE) and liquid ion exchange (LIE). SSIE is conducted by calcining a physical mixture of H-SAPO-34 zeolite and CuO nanoparticles at elevated temperatures (500–800 °C). The conventional LIE method is conducted by exchanging Na-SAPO-34 with Cu(COOCH3)2 aqueous solution with a final calcination step at 500 °C. Catalysts were fully characterized, focusing on Cu species identification. The NH3-SCR activity is evaluated for NOx removal. Cu/SAPO-34 catalysts synthesized by SSIE at 700 °C achieved an optimal reaction rate, which was correlated with a higher proportion of Cu2+ ions. The activation energies of Cu/SAPO-34 catalysts prepared by SSIE and LIE with varying copper loadings are 32–38 and 42–47 kJ mol–1, respectively. The SSIE catalysts achieve higher turnover frequency than LIE catalysts for a similar copper content, which decreases on increasing the copper loading. These results provide evidence that Cu ions exchanged into the Cu/SAPO-34 catalysts synthesized by SSIE present higher activity than those prepared by LIE for NOx removal by NH3-SCR.

Effective adsorptive denitrogenation from model fuels over yttrium ion-exchanged Y zeolite

Abstract The adsorption removal of indole and quinoline in octane with and without toluene over zeolites NaY and Yttrium Ion-exchanged Y (YY) using batch adsorption experiments was studied at 25 o C and 1 atm. YY was prepared by treating NaY with Y(NO 3 ) 3 solution twice via liquid ion-exchange method. NaY and YY were both characterized by XRD, SEM, N 2 adsorption, XRF, NH 3 -TPD, and pyridine-FTIR techniques. Adsorption isotherms of indole, quinoline and toluene in octane were conducted at 25.0 o C to explain the influence of toluene on nitrogen removal over NaY and YY. The partial destruct of the crystalline structure of NaY was observed after the introduction of yttrium ion , which led to an evident decline in BET surface area and pore volume of YY. Strong Bronsted acidity and medium Lewis acidity were introduced by yttrium ion-exchange. Though the specific surface area and pore volume of YY were much lower than those of NaY, YY exhibited equivalent adsorption capacities for indole and quinoline as NaY in model fuels without toluene. In the presence of 20 vol.% toluene, however, YY exhibited much higher adsorption capacities for indole and quinoline than NaY, especially in the case of quinoline. The improved toluene-tolerant of YY was ascribed to the strong acid-base interaction between YY and quinoline and the decreased adsorption strength between YY and toluene.

Catalytic Ozonation of NO with Low Concentration Ozone over Recycled SAPO-34 Supported Iron Oxide

A series of SAPO-34 supported iron oxide (FeOx/SAPO-34) catalysts were prepared by a two-step liquid ion-exchange method. The effects of the exchange time and iron nitrate concentration on the structure and properties of the catalysts were investigated. The results showed that the FeOx/SAPO-34 catalysts significantly enhanced the ozonation of NO. The 0.05-FeOx/SAPO-34-15 catalyst prepared by mixing NH4+/SAPO-34 with 0.05 M iron nitrate solution for 15 h showed the most effective NO oxidation. Oxygen vacancies acted as the active sites for the catalytic oxidation of NO. The electron paramagnetic resonance results showed that the hydroxyl and superoxide radicals generated from ozone and the oxygen vacancies on the surface of the catalysts promoted the oxidation of NO. The 0.05-FeOx/SAPO-34-15 catalyst has a certain stability when the volume fraction of water vapor is in the range 0–8%.

液相イオン交換法によって調製したFe/ZSM-5によるNH3-SCR

液相イオン交換法によって調製したFe/ZSM-5によるNH3-SCR

Characterization and water adsorption properties of Ag- and Zn-exchanged A zeolites

Ag- and Zn-exchanged A zeolites are prepared by the liquid ion exchange method following the procedure reported in our previous studies. Samples with Ag and Zn metal loadings are obtained and characterized by physicochemical and thermal analyses. The obtained materials with improved physicochemical properties are promising candidates for use as haemostatic agents. Both powder X-ray diffraction and nitrogen adsorption measurements show good conservation of the zeolitic structure and texture after ionic exchange. Porosity measurements indicate that the variation of the porous volumes and the specific surface areas depends on the number and nature of exchanged cations. Thermal behavior of water adsorption studied by using TGA microbalance and differential scanning calorimetry highlights clearly the complexity of the adsorption and diffusion mechanisms of water molecules within the micropores of exchanged zeolites. The differences between sorption rates and hydration heats appear to be due mainly to the location and migration of Ag, Ca and Zn species in the cationic position of the A zeolite framework. The exothermicity of adsorption is attenuated by Ag and Zn exchange.

The role of various iron species in Fe-β catalysts with low iron loadings for NH3-SCR

A series of Fe-β catalysts, containing 0.17–0.52 wt% Fe, were prepared by a liquid ion-exchange method to study the influence of various iron species on NH3-SCR activity.

Catalytic upgrading pyrolysis vapors of Jatropha waste using metal promoted ZSM-5 catalysts: An analytical PY-GC/MS

HZSM-5 with high surface area of 625 m2/g was successfully synthesized by hydrothermal method at 160 °C for 72 h. The metal promoted on HZSM-5 catalyst was prepared by liquid ion exchange method. From XRD results, the addition of metals such as Co and Ni did not change the HZSM-5 structure. The metal/HZSM-5 showed lower crystallinity and surface area than the parent HZSM-5 because of the metal dispersion on the HZSM-5 surface. The metal contents of Co/HZSM-5 and Ni/HZSM-5 detected by EDX were less than 1 wt%. Catalytic fast pyrolysis of Jatropha waste using HZSM-5 and metals/HZSM-5 was investigated in terms of biomass to catalyst ratios (1:0, 1:1, 1:5 and 1:10) and types of metals (Co and Ni). From the results, it can be concluded that both biomass to catalyst ratios and the presence of metals had an effect on the increase in aromatic hydrocarbons yields as well as the decrease in the oxygenated and N-containing compounds. Both Co/HZSM-5 and Ni/HZSM-5 promoted the production of aliphatic compounds. Additionally, the PAHs compounds such as napthalenes and indenes, which caused the formation of coke, could be inhibited by metal/HZSM-5, particularly, Ni/HZSM-5. Among catalysts, Ni/HZSM-5 showed the highest hydrocarbon yield of 97.55% with N-containing compounds remained only 1.78%. The formation of hydrocarbon compounds increased the heating values of bio-oils while the elimination of the undesirable oxygenated compounds such as acids and ketones could alleviate problem regarding acidity and instability in bio oils.

Fe-Modified ZSM-5 and β Zeolites for Direct N<sub>2</sub>O Decomposition

Fe-modified ZSM-5 and β zeolites were prepared by adopting liquid ion-exchange method and their catalytic performance was studied in the N2O decomposition reaction. The state of Fe loaded on Fe-zeolites was investigated by means of UV-vis diffuse spectra, infrared spectroscopy, EPR and H2-TPR. The results of IR of hydroxyl stretching and UV-vis investigationSubscript texts indicated that part of the iron-ions was introduced into zeolites at the charge-balancing sites. The results of EPR and H2-TPR investigations showed that the same iron species were loaded on ZSM-5 and β zeolites. However, the results of IR of the perturbed anti-symmetric T-O-T vibrations of iron-ions indicated that different types of ZSM-5 and β zeolites resulted in different distributions of charge-balancing iron cations. The iron-ions could replace Brönsted acid protons at the straight channel wall (α sites), intersection of straight and sinusoidal channels (β sites), and sinusoidal channel wall (γ sites) within the ZSM-5 zeolite. In the case of Fe-β zeolites, iron-ions mainly located in the straight channels. We observed that the catalytic activity of the iron ions located on the α sites of ZSM-5 zeolites was better than those of iron ions located on β and γ sites in N2O direct decomposition, since the former was the most easily reduced from Fe3+to Fe2+in H2. Furthermore, it was found that Fe-β zeolite showed higher catalytic activity than Fe-ZSM-5 zeolite. This difference was attributed to the active sites located almost exclusively in the straight zeolite channels.

Reduction of N2O by CO over Fe- and Cu-BEA zeolites: An experimental and computational study of the mechanism

The catalytic reduction of N2O by CO over two types of modified beta zeolite (BEA) catalysts, i.e. Fe modified beta (Fe-BEA) and Cu modified beta (Cu-BEA), was investigated. Catalytic tests for N2O direct decomposition and reduction by CO over Fe-BEA prepared by liquid ion exchange method were performed through a fixed-bed reactor. The experimental results showed that N2O conversion is apparently improved using CO as reductant; Fe-BEA starts to reduce N2O from 513K; a complete N2O conversion is achieved at 650K; and the required temperature for this reaction is reduced by ca. 150K. The reaction mechanism over Fe-BEA was investigated by in situ FTIR and DFT methods with 5T [(Si(OH)3)4AlO4(Fe) or (FeO)] cluster models. For Cu-BEA, a 5T [(Si(OH)3)4AlO4(Cu)] cluster model was established to optimize the geometries of reactants, transition states, and products. Two different reaction routines, namely the redox mechanism and the associative mechanism, have been investigated for the reduction of N2O by CO over both Fe- and Cu-BEA. It was found that for Fe-BEA, the energy barrier over the [Fe]+ active site is much lower than that over [FeO]+ active site; the redox mechanism is preferred for both Fe- and Cu-BEA; and the energy barrier on [Cu]+ active site is higher than that on [Fe]+ active site, indicating that Fe-BEA is superior to Cu-BEA for the reduction of N2O by CO.

Adsorption of Thiophene Out of Model Gasoline Using Metal Ion-Exchanged Zeolite

Adsorptions of organic sulfur compounds thiophene was carried out using metal ion-exchanged Y-zeolites. Na-Yzeolites exchanged with Ag+, La3+, Cu2+, Ni2+, Bi3+ions were prepared by liquid ion exchange method. Ag+and La3+ions modified Yzeolites showed markedly high adsorptive capacities for Thiophene. The sulfur uptake increased in the order of Bi-Yzeolite < Ni-Yzeolite < CuY-zeolite < AgY-zeolite < LaY-zeolite for thiophene. The mole ratios of TP/Ag and TP/La were 0.098 and 0.071, respectively.

Natural Micas Intercalated with Al2O3 and Modified with Transition Metals as Catalysts of the Selective Oxidation of Ammonia to Nitrogen

Natural cationic layered clays—vermiculite and phlogopite—pretreated with acids were intercalated with alumina pillars. In next step, transition metals were deposited on the surface of pillared interlayer clays (PILC) by a liquid ion exchange method. The catalyst samples were characterized with respect to: composition (EPMA), structure (XRD), texture (BET), surface acidity (NH3-TPD) and coordination of deposited transition metals (UV–vis-DRS). The modified clays were tested in the role of catalyst for the selective oxidation of ammonia to nitrogen. In a series of the studied samples the best catalytic performance presented alumina pillared vermiculite modified with copper.

The Effect of Different Active Sites on the Catalytic Activity of Fe-ZSM-5 Zeolite for N2O Direct Decomposition

Fe-modified ZSM-5 zeolites (Si/Al = 25) were prepared by adopting the liquid ion-exchange method with nitrate and oxalate of iron as Fe precursors and their catalytic performance was studied in the N2O decomposition reaction. The results of FT-IR and H2-TPR investigations indicated that (i) part of the iron ions could replace Bronsted acid protons at the straight channel wall (α sites), intersection of straight and sinusoidal channels (β sites), and sinusoidal channel wall (γ sites) within the ZSM-5 zeolite; and (ii) different Fe precursors gave rise to various distributions of α, β, and γ sites. We observed that the Fe-ZSM-5 catalyst prepared with iron oxalate as Fe precursor outperformed the ones prepared with iron nitrate as Fe precursor in the direct decomposition of N2O. Furthermore, the catalytic activity of iron ions located at the α sites was higher than those of iron ions located at the β and γ sites.

Preparation and antimicrobial ability of natural proous antibacterial materials

The liquid ion exchange method, solid salt melt method and dry-wet circulation method were used to prepare natural porous antimicrobial materials with natural minerals, such as zeolite, spilite, palygorskite and montmorillonite, respectively. Atomic absorption spectrum and X-ray diffraction analysis were carried out to investigate the effects of Ag+, Cu2+ and Zn2+ on antimicrobial abilities of natural porous minerals, and the effect of preparation method on ion exchange capacity of antimicrobial material, respectively. The results show that for the ion exchange capacity, clay mineral is higher than fibrous mineral, i. e. both zeolite and montmorillonite are higher; the antimicrobial ability of material with Ag+ is the best; the exchange capacities of materials with Cu2+ or Zn2+ are all higher, but the antimicrobial ability of Cu2+ is better than that of Zn2+.