Y-type Zeolite Research Articles

Catalytic co-pyrolysis of yellow poplar and HDPE using MOF-incorporated HY zeolite catalysts

Catalytic co-pyrolysis of yellow poplar and high-density polypropylene (HDPE) was conducted using metal oxide on hydrogen y-type (HY) zeolite to selectively produce monoaromatic hydrocarbons. The reaction was investigated using a tandem micro-reactor connected to a gas chromatography–mass spectrometry (GC–MS) system, encompassing both in-situ and ex-situ studies. Fe oxide/HY and Cu oxide/HY catalysts, prepared via a metal–organic framework (MOF)-incorporated technique, demonstrated excellent metal dispersion and enhanced electron density. The Cu oxide/HY catalyst showed significant production of benzene, toluene, ethylbenzene, and xylene, reaching up to 28% in in-situ studies. Owing to its strong acid sites, this catalyst facilitated the formation of aromatic compounds. In ex-situ studies, furan and acetaldehyde were consumed through the Diels–Alder reaction. The increase in aromatic compounds was highlighted by a synergistic effect percentage as high as 175%. The mechanism of aromatic formation was elucidated through dealkylation, Diels–Alder, and aromatization reactions. The Cu oxide/HY catalyst, combined with the MOF-incorporated preparation technique presents a promising system for catalytic co-pyrolysis of biomass and HDPE. This approach will facilitate efficient and sustainable aromatic hydrocarbon production from renewable and plastic waste sources.

Synthesis of benzoic acid from catalytic co-pyrolysis of waste wind turbine blades and biomass and their kinetic analysis

This work aims to study the catalytic co-pyrolysis of waste wind turbine blades (WTB: consists of fiberglass/unsaturated polyester resin) and woody biomass (WB) over ZSM-5 and Y-type zeolite catalysts for the production of benzoic acid. The experiments were performed on an equal combination of WTB and WB (WTB/WB) and a fixed amount of catalyst (50 wt%) using a thermogravimetric (TG) analyser at 10, 20 and 30 °C/min. The evolved products from the catalytic co-pyrolysis process were recognized using TG-FTIR and GC/MS. The kinetic and thermodynamic characteristics of catalytic co-pyrolysis was studied using various linear and nonlinear approaches. Also, the decomposition curves were predicted mathematically using an artificial neural network algorithm. The results revealed that the mixture was decomposed in the presence of both catalysts in the form of dual decomposition peaks at 361–374 °C and 428–443 °C, respectively. Based on TG-FTIR results, the CO stretching and carbon dioxide clusters were their main functional groups. While the GC-MS analysis revealed that the released vapours were completely free of toxic styrene (the main compound of resin) and the catalytic co-pyrolysis treatment succeeded in converting it into highly abundant benzoic acid, especially at 10 °C/ min, with an estimated 71.4 % (ZSM-5) and 64 % (Y-type). Whereas the activation energy was estimated at 262–295 kJ/mol (ZSM-5) and 319–357 kJ/mol (Y-type) with almost similar reaction complexity when compared to the case of absence of catalysts. Finally, the developed ANN algorithm showed high efficiency in predicting TG decomposition zones for both WTB/WB mixtures over zeolite catalysts with R2 more than 0.99. These results demonstrate that WB and zeolite catalysts can be used for upgrading the pyrolysis oil of WTB and eliminate its toxic styrene and convert it into benzoic acid and other aromatic hydrocarbons compounds (such as benzene, alanine, and 2-Propanamine).

Effect of Carrier Materials for Active Silver in Antibacterial Powder Coatings

Environmentally friendly powder coatings which have the advantages of being VOC-free, low-cost, and high-efficiency with a high recovery rate have been attracting increasing research attention. The introduction of antibacterial agents into the powder coatings endows them with a capacity to kill bacteria and viruses on the surface of objects; additionally, this enables them to inhibit the indirect transmission of pathogenic microorganisms. Silver, possessing broad-spectrum, strong, and stable antibacterial properties, is considered to be a promising antibacterial material for use in coating applications. Carrier materials for active silver play an important role in its activity and stability. However, there is a lack of systematic studies on the effects of different types of carriers in such coating systems, especially in green powder coating systems. In this paper, we investigated two types of carriers for active silver agents: zeolite, i.e., Linde type A (LTA) zeolite and Y-type zeolite; clay-based materials, i.e., montmorillonite and vermiculite. All the agents showed high antibacterial activity, with antibacterial rates of over 99% as compared to commercial agents. Among the four agents, the Ag-LTA zeolite antimicrobial agent showed a reduction rate of over 99.99%; additionally, it maintained a reduction rate of 99% after seven washing cycles. Thus, this agent was demonstrated to have the highest effectiveness and high durability; these features can be attributed to the high silver content and small particle size. The LTA zeolite also provides a protective effect for silver ions, protecting them from reduction, due to the restriction of elemental silver formation within the confined interior space of the α-cage structure. The Y-type zeolite antimicrobial agent exhibited a slightly lower antimicrobial performance due to its higher silicon-to-aluminum ratio and its lower cation exchange capacity. Comparatively, antimicrobial agents utilizing clay-based carriers have lower cation exchange capacity, resulting in poorer antimicrobial effectiveness than zeolite carriers. In addition, silver loaded on clay-based materials is prone to detach from the carrier and undergo a reduction reaction, making the coating yellowish in color. This study first provides information on the roles of different types of carriers in powder coating systems; then, this information guides the selection of carriers for active silver for the development of efficient antimicrobial agents and coatings.

Dual-alkali treatment of Y-type zeolite synthesized from lithium-silicon powder waste for enhanced adsorption removal of low-concentration toluene

In this study, the dual-alkali treatment of the Y-ZLSP zeolite recycled from lithium-silicon powder (LSP) waste for enhanced adsorption removal of low-concentration toluene was systematically studied. The results revealed that a mild condition dual-alkali treatment of Y-ZLSP significantly improved its toluene adsorption performance, as well the regenerability and robustness. The Y-ZLSP-NT(1/1) that was obtained under the conditions of NaOH and TPAOH molar ratio at 1/1, total concentration of 0.0050 M, and treated at 55 °C for 0.5 h showed the best adsorption property, with a saturated adsorption capacity (qs) of 139.7 mg/g at 1000 mg/m3 inlet concentration. Importantly, it had an up to 112.1 mg/g high of breakthrough adsorption capacity (qb). Toluene adsorption on Y-ZLSP-NT(1/1) was governed by physical adsorption, primarily due to pore filling and hydrogen bonding. The dual-alkali treatment resulted in a controllable pore evolution and greatly enriched the surface acid functional groups of Y-ZLSP. The evolved microporosity provided more adsorption sites, the mesoporosity afforded mass transfer channels. The toluene adsorption on Y-ZLSP-NT(1/1) follows a pseudo-first-order model and is typically an entropy-driven exothermic process with ΔH, ΔG and ΔS of −1.98 kJ/mol, −8.29 kJ/mol and 34.50 J/(mol·K), respectively.

Effective catalytic hydroconversion of benzyloxybenzene and oxydibenzene to cyclanes over nickel-supported Y-type zeolite catalyst: Lignite-related model compounds to high-density fuels

The catalytic hydroconversion (CHC) of benzyloxybenzene (BOB) and oxydibenzene (ODB), two typical lignite-related model compounds (LRMCs) representing α-Ο-4 and 4-O-5 model linkages, have been investigated using uniformly dispersed Ni15/HY prepared by a three-step method. The cleavage of >CH-O- bridged bonds in BOB and partial hydrogenation of ODB are considered as a crucial first step, and the target reactions in this work are to produce complete hydrodeoxidized ring saturation products. Through the exploration of reaction mechanism, H+/H- and biatomic active hydrogen, as the main hydrogen species involved in the reaction, play an important role in the CHC of BOB and ODB. Herein, the synergic effect between the hydrogenation of nickel nanoparticles and the acidic function of Y-type zeolite improves the CHC performance, resulting in Ni15/HY displaying proficient catalytic activity and selectivity for the CHC of BOB and ODB. Under the optimal reaction conditions, BOB and ODB can be completely converted to cyclanes over Ni15/HY, and the main products are dicyclohexylmethane (57.6 %) and cyclohexane (92.4 %), respectively. The developed Ni15/HY can not only promote the hydroconversion of BOB and ODB to produce ring-saturated products, but also undergo the rearrangement reaction to produce two- or three-ring cyclanes, which is desirable to upgrade LRMCs to high-density hydrocarbon fuels.

Impact of Low-Temperature Water Exposure and Removal on Zeolite HY.

Aqueous-phase postsynthetic modifications of the industrially important Y-type zeolite are commonly used to change overall acid site concentrations, introduce stabilizing rare-earth cations, impart bifunctional character through metal cation exchange, and tailor the distribution of Brønsted and Lewis acid sites. Zeolite Y is known to undergo framework degradation in the presence of both vapor- and liquid-phase water at temperatures exceeding 100 °C, and rare-earth exchanged and stabilized HY catalysts are commonly used for fluidized catalytic cracking due to their increased hydrothermal resilience. Here, using detailed spectroscopy, crystallography, and flow-reactor experiments, we reveal unexpected decreases in Brønsted acid site (BAS) density for zeolite HY following exposure even to room-temperature liquid water. These data indicate that aqueous-phase ion-exchange procedures commonly used to modify zeolite Y are impacted by the liquid water and its removal, even when fractional heating rates and inert conditions much less severe than standard practice are used for catalyst dehydration. X-ray diffraction, thermogravimetric, and spectroscopic analyses reveal that the majority of framework degradation occurs during the removal of a strongly bound water fraction in HY, which does not form when NH4Y is immersed in liquid water and which leads to reduced acidity in HY even when dehydration conditions much milder than those typically practiced are employed. Na+-exchanged HY prepared via room-temperature aqueous dissolution demonstrates that Brønsted acid sites are lost in excess of the theoretical maximum that is possible from sodium titration. The structural impact of low-temperature aqueous-phase ion-exchange methods complicates the interpretation of subsequent data and likely explains the wide variation in reported acid site concentrations and catalytic activity of HY zeolites with high-Al content.

Catalytic Activity of Nonaggregating Cu Nanoparticles Supported in Pores of Zeolite for Aerobic Oxidation of Benzyl Alcohol.

Cu nanoparticles (NPs) as catalysts have the good advantage of being more abundant than noble metal NPs. In this study, we synthesized nonaggregating Cu NPs supported in Y-type zeolite by the photoreduction method. In this method, Cu ions in pores of zeolite can be slowly reduced with a small amount of reductant at room temperature. The high-resolution transmission electron microscope, energy dispersive X-ray spectroscopy, X-ray diffraction patterns, and UV-Vis spectra supported that nonaggregating Cu NPs existed in the pores of zeolite. Catalytic activities of Cu NP-zeolite were investigated for the aerobic oxidation of benzyl alcohol. Our Cu NP-zeolite had a large turnover frequency of 17 h-1. The yield of benzaldehyde increased in proportion to the amount of Cu loading at ≤0.5 wt %, indicating that Cu NPs in pores of zeolite work as catalysts for selective aerobic oxidation of benzyl alcohol. The high catalytic activity was brought by nonaggregating Cu NPs in pores of zeolite. The catalytic reaction for other aromatic alcohols with electron-donating groups proceeded, whereas it did not proceed for the aromatic alcohols with electron-withdrawing groups or aliphatic alcohols, indicating that the interaction between zeolite and the benzene ring also contributed to the reaction. This study would be expected to contribute to the development of Cu NP catalysts.

Synthesis of value-added aromatic chemicals from catalytic pyrolysis of waste wind turbine blades and their kinetic analysis using artificial neural network

This research aims to convert the resin fraction of waste wind turbine blades (WTB) into value-added aromatic chemicals using catalytic pyrolysis. The catalytic study on WTB made of glass fibre/unsaturated polyester resin (UPR) was performed on two different types of zeolite catalysts (ZSM-5 and Y-type) using a thermogravimetric (TG) analyser. The effect of catalyst and heating rate on the abundance and composition of the synthesised aromatic chemicals was observed using TG-FTIR and GC/MS. The kinetics and thermodynamic behaviour of catalytic pyrolysis of WTB was also studied using traditional modelling techniques (KAS, FWO, Friedman, Vyazovkin, and Cai) and an artificial neural network (ANN). TG-FTIR results showed that the gases released from the catalytic process were very rich in aromatic groups, while GC/MS analysis revealed that benzene, toluene, and ethylbenzene (BTE) were the main constituents of the synthesised aromatic chemicals with abundance estimated at 36% (ZSM-5 at 10°C/min) and 64% (Y-type at 15°C/min) accompanied by a significant reduction in styrene formation up to 16.2% (main toxic element in the UPR). Besides, it contributed to reduction of the activation energy of the reaction up to 126 KJ/mol (ZSM-5) and 100 KJ/mol (Y-type). The trained ANN model also showed high performance in predicting the thermal decomposition zones of WTB at unknown heating rates with R2 close to 1. Accordingly, the use of catalytic pyrolysis of WTB over a Y-type zeolite catalyst is highly recommended for decomposition of UPR to aromatic chemicals BTE and reduction of styrene in the produced fuel.

Two-stage conversion of CO2 to methanol and dimethyl ether using CuO–ZnO–Al2O3/protonated Y-type zeolite catalysts

The CuO-ZnO-Al2O3/protonated Y-type zeolite (CZA/HYZ) catalysts were prepared via co-precipitation method and employed in a two-stage CO2 conversion process using a dual fixed–bed column at different temperatures and 50 bar. Catalytic components of CZA/HYZ were copper species that have been identified with XPS. Remarkably, the fine structures of CZA/HYZ catalysts metal atoms were confirmed with XANES and EXAFS spectra. Molecular configurations of catalytic species in CZA/HYZ catalyst simulated from the XANES/EXAFS spectra-analyzed fine structural parameters were schematically displayed. The optimal catalytic performances of CZA/HYZ (CH3OH conversion=78.0%, CH3OCH3/HCOOH selectivity=91.7%/8.3%, CH3OCH3/HCOOH yield=71.5%/6.5%) were achieved at 250 ºC. The Arrhenius equation and a pseudo-first-order/second-order model were used to evaluate the activation energies and rate constants of CH3OH and CH3OCH3 formations at various catalytic temperatures. The low activation energies (2.720 and 1.160 kJ mol−1) and Gibbs energies (3.26 and −40.00 kJ mol−1) of CH3OH and CH3OCH3 formations at 250 ºC, demonstrated that their spontaneities were remarkably improved via CZA/HYZ, respectively. The total income from a 10–ton per day (10–TPD) for a petrochemical refinery plant waste gas utility process was USD $43,557d−1, as well a payback of 3.23 years, based on cost evaluation. The proposed process provides a continuous two-step process for manufacturing high–value-added chemicals using industrial CO2 emitted and syngas.

Adsorption/Desorption Performances of Simulated Radioactive Nuclide Cs+ on the Zeolite-Rich Geopolymer from the Hydrothermal Synthesis of Fly Ash

The operation of nuclear power plants generates a large amount of low- and intermediate-level radioactive waste liquid. Zeolite-rich geopolymers, which are synthesized under hydrothermal conditions from industrial waste fly ash, can effectively immobilize radioactive nuclides. In this study, the synthesis law of zeolite-rich geopolymers and the adsorption/desorption performances of radioactive nuclide Cs+ were researched using XRD, SEM and ICP. The results show that the increase in curing temperatures and NaOH concentrations leads to the transformation of Y-type zeolite to chabazite and cancrinite at low NaNO3 concentrations. However, at high NaNO3 concentrations, NaOH above 2 M has no obvious effect on the phase transformation of the main zeolite of chabazite and cancrinite. In the adsorption and desorption experiment of Cs+ on the chabazite/garronite-rich geopolymer, it was found that the adsorption of Cs+ in the low initial concentration range is more suitable for the Freundlich equation, while the Langmuir equation fits in the adsorption process at the high initial concentration range. Moreover, the desorption kinetics of Cs+ are in good agreement with the pseudo-second-order rate equation. Thus, the adsorption of Cs+ on chabazite/garronite-rich geopolymers is controlled by both physical and chemical reactions, while desorption is a chemical process.

Synthesis of binder-free pelletized Y zeolite for CO2 capture

Y-type zeolites are widely used in the carbon dioxide (CO2) adsorption applications due to their exceptional ion exchange performance and high stability. However, the pelletization of Y powder by adding binders such as kaolin often results in performance drops, which has limited its industrial application. This study employs a zeolite-kaolin blend to produce cylindrical pelletized Y zeolite, in which the kaolin is then transformed to zeolites via hydrothermal crystallization, resulting in binder-free Y pellets. The Design-Expert software and the response surface method (RSM) are employed to optimize the hydrothermal crystallization conditions for binder transformation, with the objective of attaining a maximized capacity for CO2 adsorption. Results demonstrate that optimized synthesis conditions yield cylindrical Y zeolite with a notable CO2 adsorption capacity of 5.52 mmol/g at 298 K and 1 bar, surpassing that of the initial Y powder. The average crushing strength is 110 N per particle (Diameter × Height = 3 mm × 3 mm). The IAST selectivity of CO2/N2 (15/85) is 824 at 298 K and 1 bar. The reaction mechanisms of the binder transformation are also investigated via experiments and DFT simulation. This study presents a simple and reliable method for manufacturing binder free Y zeolite, which is promising for carbon capture applications.

Unary Adsorption Equilibria of Hydrogen, Nitrogen, and Carbon Dioxide on Y-Type Zeolites at Temperatures from 298 to 393 K and at Pressures up to 3 MPa.

The equilibrium adsorption of CO2, N2, and H2 on commercially available Zeolite H-Y, Na-Y, and cation-exchanged NaTMA-Y was measured up to 3 MPa at 298.15, 313.15, 333.15, 353.15, and 393.15 K gravimetrically using a magnetic suspension balance. The chemical and textural characterization of the materials was carried out by thermogravimetric analysis, helium gravimetry, and N2 (77 K) physisorption. We report the excess and net isotherms as measured and estimates of the absolute adsorption isotherms. The latter are modeled using the simplified statistical isotherm (SSI) model to evaluate adsorbate-adsorbent interactions and parametrize the data for process modeling. When reported per unit volume of zeolite supercage, the SSI model indicates that the saturation capacity for a given gas takes the same value for the three adsorbents. The Henry's constants predicted by the model show a strong effect of the cation on the affinity of each adsorbate.

Effect of intergranular connectivity of NaAlB14 on Na+ extraction

This study investigated the effect of intergranular connectivity when Na+ was extracted from polycrystalline NaAlB14 to the Y-type zeolite via anisotropic ion diffusion control (ADC) and high-pressure diffusion control (HPDC) methods. Despite the low chemical intergranular connectivity in NaAlB14 without pre-annealing, Na+ was homogeneously extracted via HPDC process. Although the HPDC can form a strong physical compression between particles, the intergranular domain of the sample was oxidized by the backflow of oxide ions from the zeolite. Such oxidization can be solved by pre-annealing for chemical intergranular connectivity. In the case of Na+ extraction via ADC process, Na+ remained at the cathode side even after the treatment for 230 h. From the comparison between ADC and HPDC processes, a strong physical compression between particles by applying pressure can promote the diffusion of Na+. Therefore, pre-annealing and high-pressure applications are essential for ion diffusion control techniques.

Production of High-Efficiency Alternative Biodiesel from Transesterification of Waste Cooking Oil Using an In-house Made Y-Type Zeolite Catalyst

Production of High-Efficiency Alternative Biodiesel from Transesterification of Waste Cooking Oil Using an In-house Made Y-Type Zeolite Catalyst

Facile morphological tuning of thin film composite membranes for enhanced desalination performance

Polyamide (PA) membranes with a thin selective layer have been widely investigated for desalination and water treatment. Several modifications have been proposed over the years to tailor the morphology of such thin film composite (TFC) membranes by altering the support and/or selective layers to achieve superior performance. In this study, a facile approach towards fabricating a highly wrinkled selective layer has been demonstrated through bio-inspired modification of the support layer with Y-type zeolites. Results showed that incorporating zeolites in a smaller dimension (200 nm) produced by a unique ball milling technique is favorable for a defect-free selective layer in comparison to larger commercial zeolites. PA membranes formed by the interfacial polymerization (IP) of Piperazine (PIP) and 1,3,5-Benzenetricarbonyl trichloride (TMC) revealed highly wrinkled morphology due to the presence of zeolites in the TFC interlayer. At optimum fabrication conditions, the membrane exhibited a fast transport of 22.5 ± 2.2 Lm-2h-1bar-1 with a salt rejection of 48.6, 91.3, 99.1, and 99.5% for NaCl, MgCl2, MgSO4, and Na2SO4, respectively. Besides the unique preparation of zeolites in smaller dimensions, the novelty of this study lies in the facile membrane pretreatment before IP to achieve wrinkled PA membranes for enhanced nanofiltration performance.

Synthesis of N-Unprotected Diaryl Ketimines and Alkyl Ketimines from Ketones and Ammonia Using Porous Solid Acids with Analysis of Their Adsorption Behavior

Abstract The most atom-efficient synthetic method for N-unprotected ketimines (N-H ketimines) from ketones is the dehydration condensation reaction with ammonia (NH3). However, until now, few synthetic methods for N-H ketimines with high versatility have been known. In this study, we examined various solid acids and found that N-H diaryl ketimines with various functional groups on the aryl groups could be synthesized in high yields from diaryl ketones and NH3 under solvent-free conditions using silica-alumina (SiO2-Al2O3) or proton-exchanged Y-type zeolite (H-Y). Solid-state 13C and 15N NMR measurements indicated that the N-H ketimine formed in the pores of acidic zeolite was coordinated to NH4+ species on the pore surface. By quantum chemical calculations we also discussed the reason why the dehydration-condensation reaction between ketone and NH3, which is an endothermic reaction in a vacuum, was biased toward the product side in the actual experiment. In addition, this synthetic method can be applied to synthesize N-H alkyl ketimines with α-acidic hydrogens, which are less stable and more sensitive to hydrolysis and oligomerization than diaryl ketimines.

Effects of the Acidic and Textural Properties of Y-Type Zeolites on the Synthesis of Pyridine and 3-Picoline from Acrolein and Ammonia

A set of Y-type zeolites with Si/Al atomic ratios between 7–45 were studied as catalysts in the aminocyclization reaction between acrolein and ammonia to produce pyridine and 3-picoline. The catalytic activity tests at 360 °C revealed that the acrolein conversion increased in the order Z45 < ZY34 < ZY7 < ZY17, in agreement with the increase of the total acidity per gram of catalyst. In all cases, pyridine bases and cracking products (acetaldehyde and formaldehyde) were detected in the outflow from the reactor. The total yield of pyridines was inversely proportional to the total acidity for the catalysts, which presented large surface areas and micro- and mesoporosity. The selectivity towards 3-picoline was favored when using catalysts with a Brønsted/Lewis acid sites ratio close to 1. The formation of pyridine occurred more selectively over Lewis acid sites than Brønsted acid sites. The deactivation tests showed that the time on stream of the catalysts depended on the textural properties of zeolites, i.e., large pore volume and large BET area, as evidenced by the deactivation rate constants and the characterization of the spent catalysts. The physicochemical properties of the catalysts were determined by XRD, UV-vis, and Raman spectroscopies, infrared spectroscopy with adsorbed pyridine, N2 physisorption, and SEM-EDXS. After the reaction, the spent catalysts were characterized by XRD, Raman spectroscopy, TGA, and SEM-EDXS, indicating that the uniform deposition of polyaromatic species on the catalyst surface and within the porous system resulted in the loss of activity.

Y-Type Zeolite Synthesized from an Illite Applied for Removal of Pb(II) and Cu(II) Ions from Aqueous Solution: Box-Behnken Design and Kinetics

A Y-type zeolite was prepared from illite clay, which was activated and synthesized by a solid-phase alkali fusion technique with reduced reaction conditions and crystal methods. The optimal synthesis conditions were investigated using the Box-Behnken design for a NaOH/illite (mass ratio) of 1:2, an activation temperature of 185 °C, and an activation time of 2.7 h. The synthesized Y-type zeolites were characterized by various analytical techniques such as FT-IR, XRD, and SEM, and the results obtained show that small amounts of quartz and P-type zeolites are present in the synthesized products. The mixture was classified as a zeolitic mineral admixture (ZMA). The adsorption performance of ZMA on Pb(II) and Cu(II) in solution was evaluated by batch adsorption experiments. The results showed that ZMA had good adsorption performance for Pb(II) and Cu(II), with maximum adsorption amounts of 372.16 and 53.46 mg/g, respectively. From the investigation, it was concluded that the adsorption process is chemisorption occurring in monomolecular layers and relying on electrostatic adsorption, ion exchange and complexation of hydroxyl groups on the ZMA surface for heavy metal cations. The ZMA reusability result shows that sodium chloride has the ability to regenerate the active site by restoring the ion exchange capacity without significant loss of Pb(II) and Cu(II) adsorption.

Development of modified zeolite for adsorption of mixed sulfur compounds in natural gas by combination of ion exchange and impregnation

The economic and environmental benefits of natural gas in energy applications are widely known; consequently, the usage of natural gas has increased steadily with increasing environmental regulations in recent years. However, the widespread utilization of natural gas has been limited by regulations that require sulfur compounds to be added to natural gas for leak detection. Even traces of sulfur compounds can permanently poison the catalysts used for natural gas; hence, sulfur compounds should be removed for various natural gas applications. In this study, NaY-zeolites were modified by combining Cu ion-exchange and Na2O or CuO impregnation for adsorptive desulfurization. Adsorption experiments were conducted on gas mixtures containing ppm-level tetrahydrothiophene (THT) and tert-butyl mercaptan (TBM) in CH4 to compare the desulfurization performance of pristine and modified Y-type zeolites. The analysis results show that both Na2O and CuO caused changes in the acid sites and binding energies of metal atoms in the Cu ion-exchanged Y-zeolite. Na2O promoted the adsorption of TBM, while CuO inhibited it. Among the tested samples, the Cu ion-exchanged Y-zeolite containing Na2O showed the most efficient adsorption performance with a 3.97 wt% uptake for TBM, which is 30% higher than that of the Cu ion-exchanged Y-zeolite. The Cu ion-exchanged Y-zeolite containing CuO showed the lowest adsorption ability with a 2.21 wt% uptake for TBM.

Catalytical thermal conversion of waste fishing nets for a higher added value energy products generation and caprolactam recovery

The ongoing eutrophication processes and water pollution caused by marine plastic waste are relevant ecological problem. Collected wastes are possible alternative feedstock for additional higher added value energy product generation. Moreover, caprolactamis the main compound of nylon-6 waste fishing nets and its recovery conserves natural resources, maximizes waste economic performance, and closes the circular economy loop of the fishing net industry. In order to contribute to the creation of circular economy, investigation of pyrolysis process and the effect of catalyst synergy with different temperatures on the formulated products has been performed. This work aims to analyse the used fishing nets (FN), using TGA-DTG-FTIR systems and mini pyrolysis plant. Experiments were conducted with Y-type zeolite and ZSM-5 as catalysts with a ratio of 1 by 3 and 1 by 8, respectively. Micro-thermal analysis using the TGA-DTG-FTIR system was processed for feedstock characterization purposes, which showed that the fishing gear has one minor decomposition peak around 200 °C, and the major one around 450 °C, with a total weight loss of 88 wt%. Pyro-oils analysis showed that the main fractions could be assigned to aromatic and aliphatic hydrocarbons, such as naphthalene, styrene, and toluene. Moreover, the recovery of caprolactam shows a possibility to obtain not only energy products, but also higher added value chemical derivatives. Temperature and catalyst synergetic approach influence for the recovered products investigation showed the optimum conditions as 700 °C for the highest purity and quality products generation. Based on the results, catalytic thermal treatment at 700 °C with Y-Type could be adapted as a promising technique for extracting of caprolactam with a high yield (96 %).