X-type Zeolite Research Articles

Optimizing sustainability and profitability: A multi-step approach to the synthesis of X-zeolite from blast furnace slag

To further unlock the circular economy potential of iron and steel industry and achieve peak carbon and carbon neutrality targets, this study provides a comprehensive analysis of the high value-added use of blast furnace slag (BFS) for the synthesis of X-type zeolite. The thermodynamic and dissolution behaviors during acid leaching are investigated through theoretical analysis, identifying the optimal pH is 0–1.63 and Eh is −1.01–2.00 V. Experiments determine that there are obvious improvement in silica gel leaching ratio at 353 K, 4 mol·L−1 HCl and V(HCl):m(slag) ratio of 12:1. Obtained silica gel has 91.56 % whiteness and 86.86 % SiO2. The optimal conditions for X-type zeolite synthesis are crystallization at 363 K for 6 h, with n(SiO2):n(Al2O3), n(Na2O):n(SiO2) and n(H2O):n(Na2O) establishes as 2.8, 2.8 and 45 respectively and resulting material has high crystallinity, purity of crystals and excellent performance. Furthermore, the mechanism is elucidated from the perspective of microstructural and molecular level. Economic evaluation along with carbon tax assessment indicated that it is economically beneficial both in direct profit and potential CO2 capture. These findings emphasize the feasibility, efficacy and economy of X-type zeolite synthesis from BFS, which contributes to turning waste into treasure and promoting the concept of “Green steel”.

Synthesis of Low-Silicon X-Type Zeolite from Lithium Slag and Its Fast Exchange Performance of Calcium and Magnesium Ions.

Without the addition of silicon and aluminum sources, a pure-phase KNaLSX zeolite was successfully synthesized from the residue (lithium slag), which was produced from spodumene in the production process of lithium carbonate. The KNaLSX samples were characterized by an X-ray Diffractometer (XRD), Scanning Electron Microscope (SEM), X-ray Fluorescence Spectrometer (XRF), Thermogravimetric Differential Thermal Analysis (TG-DTA), Fourier Transform Infrared Spectrometer (FT-IR), and N2 adsorption measurement. The ion exchange capacity and the ion exchange rate of calcium and magnesium ions were measured as used for a detergent builder, and the results were compared with the standard zeolites (KNaLSX and 4A). The experimental results show that the pure-phase KNaLSX synthSynthesis and characterization of co-crystalline zeolite composite of LSX/esized from lithium slag has a SiO2/Al2O3 ratio of 2.01 with a grain size of 3~4 μm, which is close to the commercial KNaLSX sample of a SiO2/Al2O3 ratio of 2.0. The BET-specific surface area of KNaLSX is 715 m2/g, which is larger than the low-silicon X-type zeolite (LSX) synthesized from waste residue reported in the literature. The ion exchange rate constant of calcium and magnesium ions in KNaLSX is 5 times and 3 times that of 4A zeolite, respectively. KNaLSX also has a high ion exchange capacity for magnesium ion of 191 mgMgCO3/g, which is 2 times than that of 4A zeolite, and a high ion exchange capacity for calcium ion of 302 mgCaCO3/g, which meets the first-grade standard of zeolite for detergent builders in China. The work provides the basis for high-value resource utilization of lithium slag and the development of a detergent builder for rapid washing.

Lithium leach residue synthesis process of high crystallinity hydroxysodalite, NaX, NaA zeolites and solidification and migration of potentially toxic elements

Converting lithium leach residue (LLR) into zeolite can reduce environmental impacts while also producing high value-added products. However, the synthesis of zeolites by LLR under alkali fusion may result in the solidification and migration of potentially toxic elements with secondary environmental impacts. Systematic research into this subject is rare in the open literature and the mobility of toxic elements from LLR derived zeolites is yet to be understood. In this paper, we have investigated the highly crystalline synthesis of hydroxy sodalite, X-type zeolite (NaX), and A-type zeolite (NaA) without stencil agent and crystal species, which can be achieved by modulating the alkali fusion temperature, all three zeolites have greater than 90 % conversion of the major elements aluminum and silicon. Meanwhile, the leachability of thallium (Tl), beryllium (Be), and potentially toxic elements (lead (Pb), mercury (Hg), cadmium (Cd), chromium (Cr), arsenic (As), barium (Ba), copper (Cu), nickel (Ni), cobalt (Co), zinc (Zn)) was monitored by pH-dependent leaching test for LLR and three kinds of synthesized zeolites according to the Chinese standard and the emission of toxic elements during the synthesis process was analyzed, to investigate the migration and quantify the distribution of the toxic elements in the LLR to the product zeolites and the cleaning wastewater. The migration efficiency of potentially toxic elements from LLR to the product zeolite and cleaning wastewater was explored. It was found that most of the toxic elements Tl, Be and potentially toxic elements were solidified in the structure of the zeolites by ion exchange (solidification rate > 90 %), and a small portion flowed into the cleaning wastewater. Although there are toxic elements solidified in the structure, there is no significant leaching under various pH conditions, which is in line with the Chinese standard (GB/T 5085.3–2007). Therefore, it is considered that LLR realizes environmentally friendly zeolite production and does not cause secondary pollution to the environment. This work demonstrates great potential for green recycling of LLR from the lithium extraction process and introduces an environmentally friendly slag treatment technology.

Recycling of fly ash to synthesize zeolites for efficient removal of dioxins

The large amount of fly ash (FA) produced by coal-fired power plants places tremendous pressure on the environment. Meanwhile, toxic dioxins emitted from municipal solid waste incineration plants are of great concern. To address these challenges, a win-win approach was proposed to re-utilize FA for synthesis of zeolite materials for dioxins adsorption. The results indicate that the Si/Al molar ratio in the liquid-phase precursor significantly influences the distribution of Si-Al 4-membered rings (Si/Al=1) and Si-Al 4-membered rings (Si/Al=3) in the system. These units are key secondary structures of the zeolite skeleton, determining the proportions of A-type and X-type zeolites in the product. With the increasing Si/Al molar ratio of precursor, the specific surface area and Si/Al molar ratio of zeolites derived from fly ash (ZFA) both increased, while they played a positive and negative role in dioxins adsorption, respectively. The adsorption of dioxins by ZFA peaked at a Si/Al molar ratio of precursor of 1.5, reaching 4.13×105 pg I-TEF/g, surpassing activated carbon by 1.46 times. This study not only elucidates the mechanism of Si/Al molar ratio of precursor on crystalline transformation of ZFA, but also confirms the potential of ZFA in dioxins adsorption.

Iron-enhanced X-type zeolite made by coal gangue for Pb/Cd-contaminated soil remediation

Iron-enhanced X-type zeolite made by coal gangue for Pb/Cd-contaminated soil remediation

Cost-effectiveness analysis and cost-benefit analysis for X-type zeolite production from fly ash

Cost-effectiveness analysis and cost-benefit analysis for X-type zeolite production from fly ash

A novel strategy for efficient utilization of manganese tailings: High SO2 resistance SCR catalyst preparation and faujasite zeolite synthesis

Herein, a core-shell structure SiO2@Mn catalyst was successfully synthesized from manganese tailings for NO removal through selective catalytic reduction with ammonia at low temperature. In the presence of 10 % H2O and 100 ppm SO2, the SiO2@Mn catalyst exhibited excellent catalytic activity of 85 % NO conversion at 225 °C. This special core-shell was constructed by inert nano-SiO2 particles, which grew and encapsulated on the surface of manganese oxide, inhibiting the reaction between SO2 with MnOx and thus improving the SO2 resistance. Furthermore, a filter residue was generated in the process of catalysts preparation. Under proper hydrothermal conditions, the residue comprising of Si, Al, and O was used to synthesize high-crystallinity X-type zeolite. This process fully utilized manganese tailings and inspired for Mn-based catalysts design and X-type zeolite preparation, realizing the dual benefits of atmosphere purification and solid waste disposal.

Synthesis of X-type zeolite and their influence on the filtration of dye effluents

Synthesis of X-type zeolite and their influence on the filtration of dye effluents

Vapour phase Guerbet condensation of ethanol to 1-butanol on CsX zeolite

Nowadays, the conversion of ethanol into valuable chemical products is getting wider application.One of such promising processes is Guerbet condensation of alcohols, which permits the obtaining of 1-butanol from renewable raw materials that are alternatives to petroleum ones.Oxide systems combining acid and basic sites in their composition are promising catalysts for such a transformation.In this study, the efficiency of the magnesium-aluminum oxide and zirconium-oxide catalysts was compared to the activity of the cesium form of X-type zeolite produced by hydrothermal ion exchange in the condensation of ethanol to 1-butanol. The integrity of the zeolite structure was confirmed by using the XRD and XRF analysis, as well as by the IR spectroscopy.The depth of exchange of native sodium for cesium was 82%. It was also found that cesium cations are localized only in ion-exchange positions of faujasite, in places SIII (supercages) and SI` (sodalite cages). CsX zeolite acid to basic sites ratio was found tobe close to optimal for this reaction. Cesium-containing zeolite at 300 °C showsethanol 35-55 % conversion and 20-25 % selectivity for 1-butanol, which is higher than the same characteristics for zirconium samples, but slightly inferior to magnesium-aluminum oxide catalysts. The obtained results indicate the promising use of zeolites of a similar nature in the process of condensation of ethanol to 1-butanol.

Potassium supported on zeolite-geopolymer hybrid materials as a new solid base catalyst for transesterification of soybean oil

The heterogeneous base catalysts were developed from zeolite-geopolymer hybrid material (Zeo-Geo) as a new support for potassium in transesterification of soybean oil. Zeo-Geo was prepared by mixing Al metal, metakaolin, and fumed silica in NaOH solution and curing at 60 °C, 24 h and 110 °C, 12 h. The Zeo-Geo contained a mixed phase of geopolymer and X-type zeolite. The xK/Zeo-Geo with x = 5, 10 or 15 wt% potassium were prepared by impregnation of Zeo-Geo with potassium acetate followed by calcination at 400 °C for 3 h. The phases of potassium were mainly K2O and K2CO3 and the basicity increased with potassium loading. The 15K/Zeo-Geo was the most active catalyst in transesterification of soybean oil with methanol, at 70 °C providing 97.64% biodiesel yield under the optimum condition: reaction time = 3 h, methanol to oil molar ratio = 16:1 and catalyst amount = 2 wt%. The catalyst was reused in 5 cycles without a significant activity loss and leaching of active species. From this study, 15K/Zeo-Geo has a potential for further development in large-scale production.

Hetero-metal solution to construct high permselective zeolite membranes

Zeolite membranes possess great application prospects in purifying chemical substances, however, the current synthetic conditions are insufficient to eliminate defects, restricting the industrial applications of zeolite membranes. In this study, compact X-type zeolite membranes were synthesized in hetero-alkali-metal cation synthesis solutions via in-situ heating method. The obtained X-type zeolite membrane possessed a methanol/methyl tert-butyl ether (MTBE) separation factor greater than 10,000 at a permeation flux of 1.3 kg m−2 h−1. A possible mechanism for the influence of hetero alkali meatal cations on the formation of zeolite membranes was proposed, which involved structural induction and regulation of the rates of crystal nucleation and growth. The hetero-alkali-metal cations entering the zeolite crystal caused distortion of the crystal structure, which promoted transformation of the zeolite crystal structure and accelerated crystal growth. Meanwhile, the rates of crystal nucleation and growth on the surface of the support were regulated by the cooperative action of the hetero-alkali-metal cations and Na+ in the synthesis solution through their solubility for the aluminosilicate gel, leading to the formation of compact zeolite membranes. This method controlled the zeolite crystal structure and compactness of the zeolite membrane by simply adding hetero-alkali-metal cations to the synthesis solution, providing a new idea for designing defect-free membranes with high permselectivity.

Physico-chemical and adsorption study of hydrothermally treated zeolite A and FAU-type zeolite X prepared from LD (Linz–Donawitz) slag of the steel industry

ABSTRACT Sodium-rich zeolite A and zeolite X (FAU-type) samples were synthesised from LD-slag via fusion-assisted hydrothermal treatment. The physicochemical and thermal stability of the prepared samples were examined with the help of various characterisation techniques, namely, Fourier Transform Infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and thermogravimetric analysis (TGA) analysis at three different pH conditions and treatment time. Moreover, the sustainability of the crystalline phase and the corresponding zeolite network was evaluated from XRD, FTIR, TGA and Field-Emission Scanning Electron Microscopy (FESEM) analysis. Zeolite A depicts a unique cubical structure and is thermally more stable as compared to zeolite type-X. Also, zeolite A showed the highest dye removal efficiency of 98.13%, as compared to 94.47% for zeolite X, along with equilibrium sorption capacities of 25.30 and 23.57 mg g−1, respectively. In addition, the study proposes that both the synthesised adsorbents are effective and economically sustainable for cationic methylene blue adsorption. Furthermore, methylene blue adsorption was regulated by a multistage diffusion process that agreed with a pseudo-second-order kinetic model (R2 = 0.999 and 0.996 for A- and X-type zeolites). The Langmuir isotherm model best suited the equilibrium data, with monolayer adsorption capacities of 20 and 25.40 mg g−1, respectively.

Techno-economic analysis of a novel full-chain blast furnace slag utilization system

As the main solid waste in the iron and steel industry, the waste heat recovery and comprehensive utilization of blast furnace slag had great significance for energy conservation and sustainable development. This paper proposed a novel full-chain blast furnace slag utilization system to solve the problem of waste heat recovery and high value-added production. Cascade recovery of slag waste heat was realized by using coal gasification reaction and the waste heat recovery ratio reached 73.61%. Meanwhile, two kinds of high value-added products of X-type zeolite and hydrotalcite-like compounds were synthesized simultaneously by using the beneficial components of blast furnace slag after fully recovering waste heat. Ultimately, the economic feasibility of the system was analyzed from two aspects of investment and profit. Under the reasonable economic assumptions, payback period of the project was 0.14 years, 10-year net present value was $ 326493.98 million, return on investment and internal rate of return were 737.74% and 312.82%, respectively. Through sensitivity analysis, the project could still be profitable in the production year under the condition that the sensitive factors of the system fluctuated within 40%. With great economic benefit and anti-risk ability, the novel full-chain blast furnace slag utilization system had potential in energy saving and emission reduction of iron and the iron and steel industry and the prospect of large-scale application.

Direct Etherification Reaction of Glycerol Using Alkali Metal Cation (Li+, Na+ and K+) Containing X-Type Zeolites as Heterogeneous Catalysts: Optimization of the Reaction Conditions

X-type zeolite (XZ-Na) containing Na+ as a cation was synthesized, and XZ-Li and XZ-K were prepared by exchanging the cations of XZ-Na with Li+ and K+, respectively. The specific surface areas, structures, and chemical compositions of the prepared zeolites were analyzed by BET, XRD, and SEM-EDX. The activity of the direct and selective etherifications of glycerol to diglycerol (DG) and triglycerol (TG) were investigated using each zeolite XZ-M (M = Li, Na or K) as a basic heterogeneous catalyst. The etherification reactions of glycerol were carried out at atmospheric pressure while controlling the reaction temperature, reaction time, and the amount of each zeolite. As the amount of each zeolite, reaction time, and reaction temperature increased, the conversion of glycerol also increased, but the selectivities of DG and TG decreased due to the increase in the production of oligomers. When each zeolite was used as a catalyst, the catalytic activity for the conversion of glycerol was observed as XZ-K > XZ-Li > XZ-Na, but the selectivities of DG and TG were observed as XZ-Li > XZ-Na > XZ-K. Especially, 3 wt.% of XZ-Li exhibited the excellent catalytic performance when the etherification of glycerol was optimized and carried out at 280 °C for 2 h: the conversion of glycerol was 89.6% and the yields of DG and TG were 61.2 and 21.2%, respectively.

Preparation of a Gangue-Based X-type Zeolite Molecular Sieve as a Multiphase Fenton Catalyst and Its Catalytic Performance.

In this study, a series of X-type zeolite molecular sieve catalysts, modified with copper (Cu-X), were prepared by an alkali fusion–hydrothermal synthesis using coal gangue from Inner Mongolia. These catalysts were used in the degradation of the methylene blue dye by a Fenton-like reaction. Characterization results showed that Cu is considered to be present in the surface structure of the zeolite in the form of doped Cu ions and metal oxide. It is believed that Cu2+ is the main active site involved in the Fenton reaction. The X-ray photoelectron spectroscopy (XPS) spectra indicated that Cu2+ and Cu+ coexist in the catalysts and participate together in the Fenton reaction. The degradation of methylene blue by the Cu-X catalysts was investigated to determine the optimal catalytic conditions in terms of six aspects: catalyst dosage, initial solution concentration, initial pH of the solution, H2O2 dosage, copper loading, and reaction temperature. The experimental results showed that CX-1.0 had excellent activity and stability for the degradation and decolorization of the methylene blue dye, which could completely degrade the dye within 90 min, and the total organic carbon removal rate reached as high as 97.8%. Electron spin resonance (ESR) and radical capture experiments showed that •OH played a dominant role in the Fenton-like reaction. Combined with XPS, ESR, and catalytic tests, the redox cycle of Cu+/Cu2+ was found to be accelerating the generation of reactive radicals in the Fenton system.

Synthesis of zeolite from volcanic ash: Characterization and application for cesium removal

Abstract Mt. Etna, the largest volcano in Europe, is periodically interested by intensive eruption activity sometimes causing environmental problems for the neighbouring urban areas such as Catania. The volcanic ash deposited on the roads is classified as waste (code 20 03 03 – municipal waste from European Waste Catalogue - EWC). In this work, with the aim to transform waste materials into useful product, two samples of ashes resulting from different explosive activities were treated by hydrothermal aging with distilled water and seawater. The results showed that the hydrothermal process determined mineralogical and magnetic changes in volcanic ashes. The data in fact indicated that X-type zeolite and sodalite were formed at 45, 60 and 70 °C of aging temperature. Moreover, magnetic characterization suggests an evolution of ferromagnetic materials to antiferromagnetic ones during zeolite formation. The presence of these new magnetic phases was responsible for the variety of magnetic behaviour. The applicability of obtained zeolite as novel adsorbent material in the field of water treatment was also evaluated. Batch adsorption experiments were carried to assert the adsorption capacity of novel synthetized zeolite in removing cesium ions from aqueous solutions thus confirming a possible End-of-Waste alternative.

Parameters Affecting the Synthesis of X and A Zeolites from Coal Fly Ash

This paper summarizes the investigation results on the main parameters affecting the synthesis of type X and A zeolites using coal silicious fly ash (FA) as raw material. The synthesis was performed by dissolution of alkali-fused alumino-silicates, followed by hydrothermal treatment. The experimental data confirm that fly ash SiO2/Al2O3 ratio, NaOH/FA ratio, acid treatment of pre-fused fly ash, salinity of solution have a significant effect on type and properties of newly formed zeolites. In summary, the results show that A and X-type zeolite form with FA SiO2/Al2O3 ratio < 1.12 and > 1.86, respectively. Moreover, FA characterized by SiO2/Al2O3 mole ratio of 3.15 is suitable for X-type zeolite synthesis while A-type zeolite does not form without NaAlO2 addition. The crystallization occurs faster at higher temperatures although above 90°C X-type zeolite evolves into more stable phases whereas increasing the crystallization time from 1 to 72 hours, the yield of the synthetic products enhances from 60 to 75%. The use of seawater is responsible for the synthesis of X-type showing both lower purity and specific surface area. However, the synthetic products are characterized by high exchange capacity (> 320 meq/100 g), thus suggesting their successful application as adsorbents and catalysts in different types of wastewater and industrial waste treatments.

Adsorption of Zirconium Ions by X-Type Zeolite

Dependence of zirconium adsorption value on agitation time, solution acidity, equilibrium concentrations of zirconium cations, and zeolite NaX particle size was investigated. The two most common adsorption theories Langmuir and Freundlich, were used to analyzing equilibrium adsorption data. Nonlinear approximation shows that the Freundlich adsorption theory provides higher R2 and lower χ2 for zirconium adsorption by NaX than the Langmuir adsorption theory. Experimental maximum adsorption values of NaX toward zirconium and strontium cations are 75 mg·g-1 and 156 mg·g-1, respectively. The desorption studies of zirconium ions from the surface of NaX by 1% oxalic acid and 10% HNO3 were performed. Degradation of the adsorbent in nitric acid was studied in a batch mode. The recovered suspended particles filter cake was investigated by X-ray fluorescence analysis. Alumina oxide (Al2O3) fraction decreases, and MgO is completely washed out from the adsorbent matrix in concentrated HNO3.

Techno-Economic Analysis of a Novel Full-Chain Blast Furnace Slag Utilization System

As the main solid waste in the iron and steel industry, the waste heat recovery and comprehensive utilization of blast furnace slag had great significance for energy conservation and sustainable development. This paper proposed a novel full-chain blast furnace slag utilization system to solve the problem of waste heat recovery and high value-added production. Cascade recovery of slag waste heat was realized by using coal gasification reaction and the waste heat recovery ratio reached 73.61%. Meanwhile, two kinds of high value-added products of X-type zeolite and hydrotalcite-like compounds were synthesized simultaneously by using the beneficial components of blast furnace slag after fully recovering waste heat. Ultimately, the economic feasibility of the system was analyzed from two aspects of investment and profit. Under the reasonable economic assumptions, payback period of the project was 0.14 years, 10-year net present value was $ 326493.98 million, return on investment and internal rate of return were 737.74% and 312.82%, respectively. The sensitive factors of the system fluctuated within 40% through sensitivity analysis. The project could still be profitable in the production year. With great economic benefit and anti-risk ability, the novel full-chain blast furnace slag utilization system had potential in energy saving and emission reduction.

Preferential Adsorption of Propylene over Propane on a Ag-Exchanged X-Type Zeolite Membrane.

We investigated the adsorption properties of propylene and propane on an olefin-selective Ag-X membrane and discussed the contribution of adsorption selectivity to propylene/propane separation performance through this membrane. The isotherms of propylene and propane on Ag-X membranes were measured in unary systems at 313 K. The amount of propylene adsorbed on the Ag-X membrane at a lower pressure increased remarkably compared with that on the Na-X membrane. Such a change of adsorption property could induce excellent separation property for the Ag-X membrane. We compared the adsorption properties in a binary system calculated based on the Markham-Benton approach with the results of a permeation test. The molar fractions of propylene in the adsorbed phase in the binary system provided good agreement with propylene purity on the permeation side of the Ag-X membrane. These results clearly show that permeation selectivity of the Ag-X membrane for the propylene/propane mixture is mainly governed by adsorption selectivity.