Type Zeolite Research Articles

Enhanced carbon dioxide capture through composite of polyamide 6 nanofibers and zeolites: Preparation and performance evaluation

The increasing concentration of atmospheric carbon dioxide (CO2) demands innovative solutions for its capture and sequestration. Composite and nanocomposite materials have gained attention for their high surface area, adjustable properties, and improved adsorption capabilities. This manuscript explores the preparation, characterization, and performance assessment of a novel composite material consisting of polyamide 6 nanofibers combined with two types of zeolites, designed for CO2 capture. We detail the fabrication process, as well as the structural, chemical, and morphological characterization of the composites. The results confirmed the successful modification of polyamide 6 nanofibers with both types of zeolites. CO2 sorption measurements revealed that the composite with zeolite Y exhibited a notably high sorption capacity, with a maximum of 35.8 cm³/g, significantly surpassing the performance of amine-modified nanofibers, which demonstrated sorption capacities approximately three times lower. These findings highlight the potential of this composite for efficient CO2 capture, providing valuable insights into its practical application for reducing greenhouse gas emissions. While the CO2 sorption capacities of the composite are lower than those of pure zeolites, the composite offers practical advantages, such as easier handling and simplified application.

Neighbourhood Sum-Based Structural Analysis for Sodalite System

Background: Sodalite is a type of zeolite with an intricate structure comprising a system of interrelated cages and tunnels. It is extensively used in sieving applications due to its unique structure and properties. As a result, it finds several uses in water and air purifica-tion, radioactive decontamination, detergents, and so on. Due to the potential positive envi-ronmental impact of sodalite materials, analysing the molecule at a structural level becomes the need of the hour. Methods: Molecular descriptors form the basis of many convenient and cost-effective tech-niques for studying molecular structures. In this article, the neighbourhood sum-based de-scriptors are computed edge-partition techniques, simplifying the intricate structures with cages and tunnels into more simple graphs for mathematical convenience. Results: This article presents the calculated analytical expressions for molecular descriptors, specifically focusing on various neighbourhood sum degree-based indices in sodalite struc-tures. Conclusion: The results presented in this article establish the dependence of the physical properties of a molecule on its underlying structure using the computed molecular de-scriptors. The graphical comparison of the results provides a visual representation of the be-haviour of indices with respect to the molecular structure.

Ion-exchange of copper into mordenite and clinoptilolite zeolites by molecular dynamics simulations and experimental investigations

Copper-exchanged zeolites have been subjected to several investigations because of their application as selective redox-active catalysts, and sensors. However, the ability of different types of zeolites to exchange Cu ions remains a matter of debate. All-atom molecular dynamics (MD) simulations, energy dispersive X-ray spectroscopy (EDS), and X-ray Fluorescence (XRF) methods have been used to evaluate the exchange of Cu(II) in mordenite and clinoptilolite zeolites using an aqueous method in the current study. Several parameters of copper ions have been measured for both types of zeolites, such as ion exchange ratio, mean square displacement (MSD), diffusion coefficient, and radial distribution function (RDF). These parameters were calculated for each zeolite system at different Cu ion concentrations in the feed solution. Copper exchange ratio and RDF analyses revealed a higher exchange ratio of copper ions in the mordenite framework. Analysis of the potential energy indicates the major adsorption sites for mordenite and clinoptilolite, which are located in the largest cavities of the zeolites. The adsorption energy of the mordenite sites (1.52 eV) was larger than that of clinoptilolite (1.28 eV). The stronger attraction between the copper ions and mordenite sites is consistent with the lower diffusion coefficients of the ions in this zeolite. The ion-exchange abilities of the zeolites were examined using EDS analysis. According to the EDS results, the mordenite zeolite exchanged more copper ions than the clinoptilolite, which is in agreement with the computational results.

Chabazitic zeolitite in cultivation and spray protection against Phytophthora infestans and Tuta absoluta in Solanum lycopersicum

Research objective: This article aims to highlight how chabazite zeolitite can lead to better growth and protection of tomato plants, in particular the benefits it can bring to crops both when buried in the soil, in terms of plant growth and fruit production, and as a reduction in the incidence of fungal diseases and insect attack when used as a spray in water. Materials and Methods: The experiments, which began in March 2024, were conducted in the CREA-OF greenhouses in Pescia (Pt), Tuscany, Italy (43°54′N 10°41′E) on tomato cv ‘Ciliegino’ plants. The plants were placed in pots with a diameter of 14, 20 plants for 3 replications, for a total of 60 seedlings per experimental thesis. The first trial on Solanum lycopersicum involved the following theses (irrigated and fertilised): i) peat 70% + pumice 30%; ii) peat 70% + pumice 20% + zeolitite chabazite 10%; iii) peat 70% + pumice 10% + zeolitite chabazite 20%. The second trial on Solanum lycopersicum included spray treatments with micronised zeolitite on the leaves to evaluate the control of diseases such as Phytophthora infestans and Tuta absoluta. The trial included the following theses (irrigated and fertilised): i) control with treatment with water sprayed on the leaves every 10 days; ii) control with treatment with Flipper 1 L/hl + Ranman Top 0.5L/hl, every 7 days; iii) treatment with zeolitite chabazite 5 kg/hl, every 7 days. On 19 September 2024, plant height (measured at 70 days after transplanting), plant nodes (measured at 70 days after transplanting), leaf area index, total dry biomass, fresh fruit weight and number of total fruits were determined. In addition, the number of plants affected by Phytophthora infestans and Tuta absoluta was evaluated. Results and Discussion: The experiment showed that the use of zeolitite and chabazite added to the growing medium to the extent of 10-20% can effectively improve the vegetative and root growth of Solanum lycopersicum. Furthermore, when micronised zeolitite is micronised on leaves, it can contain diseases such as Phytophtora infestans and Tuta absoluta, the same as using conventional products. This experiment conducted on Solanum lycopersicum shows an improvement in plant growth in the theses treated with zeolite added to the substrate, due to increased water and nutrient uptake and increased microbiological interactions in the plant, as well as a significant improvement in protection against plant diseases when micronised zeolite is sprayed on the leaves. In addition to having an insect repellent effect, zeolite has a disintegrating and dehydrating effect. The product causes respiratory problems, burns the exoskeleton, creates flight problems and reflects light. In addition, zeolitite chabazite, having a rough structure, causes problems of adherence to the leaf. As for fungi, on the other hand, it reduces moisture on the leaf and inhibits spore germination, as demonstrated in other scientific works by the same author. Conclusions: Zeolites have the potential to affect soil physical properties. In addition to reducing soil bulk density and increasing soil porosity, these factors can improve water retention, as well as their high internal pore volume. Also, due to the open network of the zeolite structure, new routes for water movement can be formed, resulting in improved infiltration rates and saturated hydraulic conductivity. Due to their outstanding chemical and physical properties, natural zeolites can be utilized in agricultural applications, such as their affinity for K+ and NH4+ and ability to exchange cations. Before any commercial applications can be made, it is necessary to evaluate the risk of leaching toxic surfactants loosely attached to zeolite surfaces. Using their ion exchange properties, natural, synthetic, and modified zeolite can be used to make slow-release nitrogen, potassium, and sulfur fertilizers. To control and release phosphorous slowly, zeolite ion exchange and mineral dissolution (similar to phosphate rock) can also be used. It is generally determined by a variety of experimental conditions how zeolite application impacts soil physical and chemical properties, including the type and rate of zeolite applied, the method of application, the texture and structure of the soil, the size of the zeolite particles, and the salinity of the water. Soils with coarse textures may benefit from zeolite amendments more than those with fine textures.

The adsorption performance of high crystallinity Na-p zeolites prepared from oil shale ash for the waste water treatment

ABSTRACTS The Na-p type zeolite has been prepared by the alkali fusion hydrothermal synthesis method using the pure oil shale ash (OSA) and mixture of OSA and coal fly ash (CFA) as raw materials, which was used for adsorption of methylene blue (MB). The XRD spectra of zeolite synthesized from pure oil shale residue under different conditions indicated that the optimal experimental conditions were determined as follows: acid leaching concentration of 10%, sodium hydroxide dosage of 7 g, crystallization temperature of 130°C, and crystallization time of 12 h. Under the same conditions, zeolite was synthesized using the mixture of OSA and CFA, and its properties were characterized using XRD, SEM, and BET techniques. The results showed that the specific surface area and crystallinity of the zeolite prepared from the mixture were 59.6 m2/g and 86.32%, respectively, which were higher than that of pure OSA (20.6 m2/g and 64.07%). When 0.05 g of zeolite was added to the 35 mg/L MB solution and adsorbed for 180 min, the removal rates of MB by pure OSA, single-source zeolite and zeolite prepared from the mixture were 27.6%, 83.4%, and 99.2%, respectively. The adjusted R square verified that the pseudo-second-order kinetics and Langmuir isotherm model were the best fitting models. The maximum adsorption capacity (Qmax) of zeolite prepared from the mixture for MB was 55.5 mg/g. The above results proved that the novel material prepared in this study could be a potential effective wastewater treatment material.

Thermolysis of asphalt deasphalting in the presence of natural clinoptilolite

The results of a study of the process of thermal conversion (thermolysis) of asphalt deasphalting in the presence of natural zeolites are presented. Because Clinoptilolite is the most common type of natural zeolite in Russia; if the proposed process is introduced into industry, it will be provided with zeolite in the required volumes. Conditions were selected under which the most intense conversion of raw materials was observed with the formation of significant quantities of gasoline and diesel fractions, and the yield of light products depends on the silicate module of the zeolite: it increases with increasing module. Mechanical processing of clinoptilolite helps to increase its catalytic activity in the process of asphalt thermolysis.

Treating liquid anaerobic digestate using natural zeolite and Arthrospira platensis cyanobacteria: From laboratory to pilot-scale

Over the past decade, using liquid digestate as a nutrient source for microalgae cultivation has gained considerable attention. However, its high ammonium concentration and turbidity often inhibit algal growth. To address this, natural zeolite was explored as a novel approach to reduce digestate toxicity before microalgae cultivation at both laboratory and pilot-scales. Clinoptilolite, a type of natural zeolite, was applied in adsorption columns at a ratio of 0.5 kgzeolite.L-1 to treat 0.45 L of liquid digestate. After 24 h of treatment, ammonium levels decreased significantly from 2273 to 115 mgN.L-1, corresponding to a 95 % removal efficiency and an adsorption capacity of 4.31 mg.gzeolite-1. Arthrospira platensis demonstrated strong growth in the treated digestate with minimal dilution (≤5x), in contrast to the high dilution (≥20x) required for the untreated digestate. Laboratory-scale results were effectively scaled up to pilot scale, detoxifying 15.5 L of digestate with similar performances. The pretreated digestate was subsequently used as a culture medium for Arthrospira platensis in flat panel photobioreactors without further dilution, achieving a final concentration of 0.82 gDW.L-1 and a biomass productivity of 33 mg.L-1.d-1. These findings underscore the potential of natural zeolite in enhancing microalgae-based processes for digestate detoxification and CO2 mitigation.

Application of aluminosilicate residue-based zeolite from lithium extraction in water treatment

In a previous study, the Na-P1 type zeolites were synthesized from aluminosilicate residues using an efficient and cost-effective process, exhibiting an excellent adsorption capacity for Ca2+ in comparison to commercial zeolites 13X and A. Building upon this, the current study evaluates their performance for the adsorption of various elements, including Ca2+, Mg2+, and NH4+. The objective was to evaluate the performance of the Na-P1 type zeolites for the adsorption of various elements, including Ca2+, Mg2+, and rare earth elements, with a particular emphasis on the adsorption kinetics and water hardness removal in comparison to commercial zeolite A. The results demonstrated that the Na-P1 zeolite exhibited a satisfactory sorption capacity for Ca2+ and NH4+ ions (66 mg/g), while displaying a relatively lower effectiveness for the sorption of Mg2+ ions (5.6 mg/g). The Langmuir model is particularly well suited to the sorption of Ca2+, while the Freundlich model is more appropriate for Mg2+. Both models demonstrated satisfactory representation of NH₄ ⁺ sorption. Moreover, the pseudo-second-order kinetic model provides an excellent description of the Ca2⁺ and Mg2⁺ sorption processes, while both models effectively describe the NH₄⁺ adsorption kinetics. Additionally, Na-P1 zeolite was observed to effectively reduce water hardness from 322 to 63 mg CaCO₃/L at temperatures of 10, 20, and 38 °C, and to 18 mg/L at 58 °C. These findings suggest that Na-P1 zeolite has promising potential for applications as a water softening agent. Regarding metals and rare earths, the Na-P1 zeolite demonstrated noteworthy sorption efficiencies for Cd2+ (138 mg/g), Ce3+ (209 mg/g), Cr3+ (56.2 mg/g), and Cu2+ (60.5 mg/g). However, it demonstrated lower sorption efficiencies for Co2+, Mn2+, Ni2+ and Dy3+ (below 16 mg/g). The findings illustrate that Na-P1 zeolites are effective for the adsorption of diverse elements, offering a promising avenue for the sustainable transformation of industrial waste into valuable materials for environmental applications.

Seeds Combining Pyrrolidine Control the Framework Al Distribution of FER Zeolite to Enhance Its Performance in the Skeletal Isomerization of n-Butene

FER zeolites have a unique framework structure and acid distribution, and are widely studied as a catalyst for reactions such as n-butene skeletal isomerization and dimethyl ether carbonylation. The Brönsted acid site (BAS) located in the 10-member ring (10-MR) of FER zeolites serves as the active site for the isomerization reaction of skeletal n-butene to produce isobutene. This study prepared five types of FER zeolites using different methods: using pyrrolidine (PY) alone as a template; using Na-form FER as seeds (SN) or H-form FER as seeds without organic structure directing agents (OSDAs); and combining the seeds of SN or SH with PY as OSDAs. The differences in the structure and acid distribution of the five zeolites were investigated, as well as their catalytic performance for the skeletal isomerization of n-butene. Experiments and characterization results showed that under hydrothermal synthesis conditions, the FER-PY+SH zeolites synthesized by using both H-form zeolites seeds and pyridine exhibited the highest aluminum concentrations at T1 and T3 sites, along with the greatest BAS located in the 10-MR. This unique composition contributed to the highest selectivity of isobutene. The FER-PY+SH catalyst was continuously used for 720 h at 350 °C, 0.1 MPa, and an n-butene mass space velocity of 2.0 h−1 for three cycles of 2160 h. During this period, the conversion of n-butene was over 39%, while the selectivity of isobutene exceeded 95%. The FER-PY+SH catalyst exhibited excellent stability and activity.

Design of physical and functional properties of zeolitic porous monoliths by combining different foaming additives

Self-supporting zeolitic foams were synthesized by a geopolymer gel conversion process, employing silicon powder and hydrogen peroxide as foaming additives. The influence of silicon and hydrogen peroxide combination on the physical properties, mechanical characteristics, and pore distribution was studied. Correlations between these properties were drawn. This approach allows to manufacture porous monoliths tuned in terms of zeolite type and amount and characterized by bulk density ranging between 573 and 762 kg/m3 and thermal conductivity 0.33–0.53 W/mK. Pore structure, size, and distribution were dominated by the type of foaming agent: the foamed samples showed the presence of two classes of pores, the first of the order of magnitude of 1 μm, the second of the order of magnitude of 100 μm. The use of hydrogen peroxide enhanced the porosity in the meso-macropore range (0.1–5 μm). The hydrothermal treatment performed on the foamed geopolymer allowed to achieve the crystallization of zeolites within the solid geopolymer. Mainly FAU and LTA were the zeolitic phases present in the foams, whereas the use of silicon as foaming agent locally increased the Si/Al ratio on the geopolymer surface, promoting the nucleation of FAU.

Zeolite-decorated black TiOx quantum dots for photocatalytic degradation of organic cationic dyes under LED light irradiation

Defect engineering is a promising strategy to reduce the band gap of semiconductors, enhancing their photocatalytic activity under visible light by introducing intra-bandgap energy states. Among the materials studied, oxygen-deficient black TiOx stands out due to its potential in photocatalytic reduction and hydrogen evolution. However, the valence band edge maximum (VBM) of TiOx is not thermodynamically favorable for the direct oxidation of water to hydroxyl radicals (H2O/•OH). Although the formation of extensive oxygen vacancies is necessary to extend the light absorption of black TiOx to longer wavelengths, a high density of oxygen vacancies (Ov) significantly shortens the diffusion length of charge carriers within the TiOx, leading to increased recombination of electrons and holes (e-/h+), thereby suppressing photocatalytic activity. To overcome these limitations, confining TiOx particles to the quantum dot (QD) size range and constructing heterojunctions with a secondary phase can substantially improve charge carrier separation and photocatalytic performance. In addition to engineering the electronic structure of composite photocatalysts, the preaccumulation of pollutants and their subsequent degradation is an effective strategy. This method decreases the distance between the adsorbed pollutant and the active sites for reactive oxygen species (ROSs) generation, enhancing the efficiency of the photocatalytic degradation process. In this study, we confined TiOx particles to the quantum dot size range by constructing a heterojunction with H-Beta zeolite, which contains defect-induced energy states within its wide band gap. This type of zeolite is particularly effective in adsorbing cationic azo dyes, facilitating pre-accumulation and degradation. The synthesized catalysts were extensively characterized using HRTEM to determine the average size of the TiOx particles and photoluminescence (PL) analysis to investigate charge carrier separation. Our results demonstrated that while TiOx alone showed negligible degradation efficiency, and no •OH were detected, the QD TiOx/Z4 composite achieved complete oxidation of CV by •OH, as confirmed by TOC analysis. The photocatalytic degradation mechanism was proposed based on these experimental findings. These insights could be of significant interest to researchers exploring defective semiconductors for photocatalytic oxidation of organic pollutants in the liquid phase under visible light (LED) irradiation.

Investigating the deposition of fibrous zeolite particles on leaf surfaces: A novel low-cost method for detecting the presence of airborne hazardous mineral fibers

Naturally occurring fibrous minerals, such as erionite, can pose a significant threat to human health when disturbed and subsequently respired. Understanding the spatial abundance and characteristics of these hazardous fibrous minerals in ambient air is crucial for minimizing human exposure and assessing risk. Conventional detection methods for airborne hazardous mineral fibers, such as those developed for asbestos, are of limited utility in environmental settings where fiber concentrations are low and different fiber types may be present and can be costly especially when monitoring large areas over long periods of time. This study presents an innovative methodology for detecting and identifying the presence of airborne naturally occurring fibrous zeolites, using leaf surface deposition sampling, SEM-EDX analysis for the detection and assessment of elemental composition, and TEM-SAED with continuous rotation diffraction (MicroED) to determine their crystallographic unit cell parameters. In total, 309 fibrous zeolite particles (FZPs) were identified on a range of tree leaf surfaces across 80% of the sampling sites located close to both active and disused zeolite quarries in the Taupo Volcanic Region, New Zealand. The FZPs displayed various morphologies including aggregates, bundles, and fibril-like structures. Of the FZPs detected, 91.2% were < 5µm in length. Tetrahedral Si:(Si+Al) ratio results indicated that 40% of the FZPs were in the reference range for zeolite mordenite. TEM-SAED plus MicroED analysis resulted in 61% of tested FZPs indexed to unit cell parameters that matched with mordenite. This research demonstrates the potential of leaf sampling as a cost-effective method for detecting airborne FZPs while the MicroED data can be utilized for distinguishing between different types of airborne fibrous zeolites in ambient air.

Spectroscopic characterization of black N- and P-doped zeolite templated carbons

The incorporation of heteroatoms (X) into the zeolite-templated carbon (ZTC) structure is a widely used technique to tailor its properties for specific applications such as gas adsorption, methane and hydrogen storage, and catalysis. However, the literature lacks sufficient data on Fourier-transform infrared spectroscopy (FTIR) analysis of ZTCs due to the challenge in obtaining high-quality FTIR spectra required for accurate assignment of the C–X bands, primarily caused by the black mass effect. In this work we prepared nitrogen (N) and phosphorus (P) doped ZTC samples using FAU type zeolite as a template and furfuryl alcohol as a carbon precursor. The Raman results confirmed the presence of medium-sized aromatic structures and also showed that doping these structures with N and P leads to some defects, although the overall conformation remains structurally intact. The FTIR spectra of the ZTC materials were obtained by controlling the preparation procedure and humidity, enabling clear analysis of the black samples. A Density Functional Theory (DFT) model based on the dimeric buckybowl structure was developed and complemented by experimental results obtained from X-ray photoelectron spectroscopy (XPS), nuclear magnetic resonance (NMR), and FTIR. The proposed DFT model was then used for deconvolution and precise band assignment of the experimental FTIR spectra. The FTIR deconvolution study also supported the incorporation of N and P into the ZTC as well as the presence of primarily two types of nitrogen species, amide (primary and secondary) and pyridine-like, while P was mainly incorporated as triphenylphosphine oxide and phosphonic acid.

Effects of Acid Sites on Thin MCM‐22 Zeolite Catalysts and Their Catalytic Applications for Acetylene Aromatization

AbstractTwo types of thin zeolite MCM‐22 catalysts were prepared by using a carbon sphere template. By applying different calcination methods, a hollow sphere‐type MCM‐22 catalyst (HS‐MCM‐22) and a nanosheet‐type MCM‐22 catalyst (NS‐MCM‐22) were synthesized. Those catalysts were tested and evaluated for acetylene aromatization to see the effects of thin structures. The two types of thin catalysts were found to have higher amounts of acid sites than those of the conventional MCM‐22 catalyst. It was found that the extremely short diffusion length not only enhanced the aromatic yield, but also suppressed the formation of graphitic coke. Notably, the diffusion length of NS‐MCM‐22 was found to be at least 15 times shorter than that of conventional MCM‐22, leading to an 11% and 18% increase in benzene yield, respectively. The thin structure seemed to help the produced aromatics efficiently desorb before they were further converted into carbon precursors and coke. According to the thermogravimetric analysis, the carbon species in the spent thin catalysts were found less graphitic than that of the conventional MCM‐22 catalyst. Because of this, the thin MCM‐22 catalysts were believed to show higher coke removal capability. Especially, the coke removal rate of NS‐MCM‐22 was estimated over 90% despite the severe carbon deposition during the reaction.

Valorizing waste activated sludge incineration ash to S-doped Fe2+@Zeolite 4A catalyst for the treatment of emerging contaminants exemplified by sulfamethoxazole

The global attention towards waste management and valorization has led to significant interest in recovering valuable components from sludge incineration ash (SIA) for the synthesis of functional environmental materials. In this study, the SIA was converted to an S-doped Fe2+-zeolite type catalyst (FZA) for the treatment of emerging contaminants (ECs), exemplified by sulfamethoxazole (SMX). Results demonstrate that FZA effectively catalyzed the activation of peracetic acid (PAA), achieving a remarkable degradation of 99.8% under optimized conditions. Mechanistic investigations reveal that the FZA/PAA system can generate ·OH, 1O2, O2·－, and Fe(Ⅳ), with ·OH playing a dominant role in ECs degradation. Additionally, the doped S facilitated electrochemical performance, Fe2+ regeneration and fixation in FZA. Practical application elucidated that the FZA/PAA system can work in complex environments to degrade various ECs without generating high-toxicity ingredients. Overall, valorizing SIA to FZA provides dual achievement in waste management and ECs removal.

Desulfurization reactions of thiophene and cyclohexane over Zn and Nb modified zeolites in FCC process

In refineries, one of the most important production units is Fluid Catalytic Cracking (FCC). In them, the incorporation of additives to the catalyst is a very interesting option to reduce the sulfur content of gasoline, and thus obtain commercial fuel specifications. In this study, the transformation of thiophene into a cyclohexane (HC) stream for its in-situ desulfurization has been investigated, using catalysts based on niobium or zinc (6 wt%) incorporated into three types of zeolites: HUSY, HBeta and HZSM-5. Catalytic tests were carried out at 773 K in an automatically controlled fixed-bed tubular reactor. The reaction products were analyzed online by gas chromatography, with FID detector for hydrocarbons and SCD for sulfur compounds, and the catalysts were characterized by XRD, FTIR, N2 adsorption isotherms, HRTEM, XRF, 29Si and 27Al solid state NMR, NH3-TPD and FTIR-pyridine techniques. The results indicate that the addition of metals did not significantly alter the textural and structural properties of the zeolites, and that the Nb/HB and Nb/HY catalysts were the most effective in the conversion of thiophene, and selective toward paraffins and H2S mainly. The performance of these materials was attributed to the existence of an optimal balance between the Brønsted and Lewis acid sites, which increased the hydrogen transfer coefficient (HTC) during the cyclohexane transformation, resulting in higher desulfurization activity. The addition of zinc drastically increased the density of the Lewis acid sites and decreased the HTC, favoring the production of aromatics and thiophene condensation reactions, thus transferring sulfur to the gasoline streams. In general, the catalysts investigated are of significant interest as additives for sulfur reduction in FCC gasoline streams, either by producing easily removable H2S or by transferring sulfur to heavier fractions.

Drying and Purification of Natural Gas on Modified Clinoptilolite Type Zeolite by Adsorption Method

Drying and Purification of Natural Gas on Modified Clinoptilolite Type Zeolite by Adsorption Method

Efficient and sustained inhibition of ammonia nitrogen release from sediment in water by microbial self-aggregation zeolite layer.

Despite global efforts to manage water eutrophication, the continual release of ammonia nitrogen from sediments maintains the eutrophic state of water bodies, presenting serious challenges to the management. In order to find an efficient method for sediment remediation, the experiment of using signal molecules to enhance the adhesion of microorganisms on zeolite was carried out. Five different zeolitic ammonium adsorptions were examined using two different signal molecules, N-(3-oxohexanoyl)-L-homoserine lactone (OHHL) and N-(β-ketocaproyl)-DL-homoserine lactone (C6), to enhance microbial attachment on two types of zeolites. The results showed that the modified microbial attached Z1 zeolite reinforced with signal molecule C6 had the best effect. The effect was better in the case of high ammonium adsorption, and the TN removal could reach 7.99mg·L-1 with an inhibition rate of 90.08%. The ammonia nitrogen removal reached 4.75mg·L-1 with an inhibition rate of 87.64%, and the ammonia nitrogen and total nitrogen of the overlying water reached the surface III water quality standard. In addition, the addition of the signal molecule increased the zeta potential on the surface of the bacterial colloid. In addition, the amount of protein I in the dissolved organic matter (DOM) fraction increased, improving microbial adhesion ability and facilitating their attachment to the zeolite surface. The signal molecule C6 could increase the zeta potential of microbial surface and promote the production of protein I, thus strengthening the attachment of zeolite biofilm and improving the water quality.

Enhancement of Gaseous o-Xylene Elimination by Chlorosulfonic Acid-Modified H-Zeolite Socony Mobil-5.

It is important to develop effective strategies for enhancing the removal capacity of aromatic volatile organic compounds (VOCs) by modifying conventional porous adsorbents. In this study, a novel HZSM-5 zeolite-supported sulfonic acid (ZSM-OSO3H) was prepared through ClSO3H modification in dichloromethane and employed for the elimination of gaseous o-xylene. The ClSO3H modification enables the bonding of -OSO3H groups onto the HZSM-5 support, achieving a loading of 8.25 mmol·g-1 and leading to a degradation in both crystallinity and textural structure. Within an active temperature range of 110-145 °C, ZSM-OSO3H can efficiently remove o-xylene through a novel reactive adsorption mechanism, exhibiting a removal rate exceeding 98% and reaching a maximum breakthrough adsorption capacity of 264.7 mg. The adsorbed o-xylene derivative is identified as 3,4-dimethylbenzenesulfonic acid. ZSM-OSO3H demonstrates superior adsorption performance for o-xylene along with excellent recyclability. These findings suggest that ClSO3H sulfonation offers a promising approach for modifying various types of zeolites to enhance both the elimination and resource conversion of aromatic VOCs.

STUDY OF THE COMBINED EFFECT OF POST-SYNTHETIC ALKALINE TREATMENT AND NICKEL MODIFICATION OF MFI ZEOLITE ON THE DYNAMICS OF ITS DEACTIVATION IN THE PROCESS OF REFINING STRAIGHT-RUN GASOLINE

To determine the combined effect of post-synthetic treatments on the catalytic properties of MFI type zeolite (other names ZSM-5 or pentasil) during the upgrading of straight-run gasoline fraction of oil, MFI zeolite was synthesized and on its basis a sample was obtained, treated with an alkaline solution, as well as a nickel-containing sample after alkaline treatment of the zeolite. Modification of zeolite powder treated with an alkaline solution with nanosized nickel powder was carried out by dry mechanical mixing of the original powders in a vibrating mill. The activity and dynamics of deactivation of the obtained zeolite catalysts during the upgrading of straight-run gasoline fraction of oil were studied. Along with determining the characteristics of the target reaction products - high-octane gasoline, an analysis of the resulting gaseous hydrocarbons was carried out and the amount of carbon compaction products was determined. It has been shown that post-synthetic treatments of zeolite have a positive effect on the qualitative composition and yield of catalysates and reduce the rate of deactivation of zeolite catalysts. Post-synthetic alkaline treatment of MFI zeolite significantly reduces its aromatizing and cracking activity, resulting in an increased yield of high-octane gasoline with improved environmental characteristics. The introduction of nickel nanopowder into alkali-treated zeolite further enhances this tendency. Carrying out post-synthetic treatments of zeolite increases the time of stable operation of the resulting zeolite systems in the process of upgrading straight-run gasoline and reduces the amount of carbon compaction products formed. The state, location and dimensions of the zeolite carrier, nickel particles and carbon compaction products were determined using the transmission electron microscopy method. It has been shown that oxidative regeneration of a carbonized catalyst makes it possible to almost completely remove the resulting carbon deposits from the surface of both the active component and the zeolite support. For citation: Velichkina L.M., Gerasimov E.Yu., Vosmerikov A.V. Study of the combined effect of post-synthetic alkaline treatment and nickel modification of MFI zeolite on the dynamics of its deactivation in the process of refining straight-run gasoline. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 8. P. 103-112. DOI: 10.6060/ivkkt.20246708.10t.