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• MLP waste was converted to valuable paraffins and olefins waxes. • Pyrolysis waxes yield obtained were between 55-61 wt%. • Paraffin wax obtained from Al-MCM-41(50) catalyst was similar to pharmaceutical wax. • Quality of MLP wax almost equal to commercial paraffin wax. Multilayer film packaging (MLP) waste was decomposed completely at 500 °C. Catalysts were employed to convert residue polymer to waxes via pyrolysis at 500 °C. The activities achieved from using mordenite (Si/Al = 10), H-ZSM-5 (Si/Al = 25), MCM-41, and Al-MCM-41 (Si/Al ratio of 25, 50, and 75) catalysts were studied. The yield and property of the wax were improved with the use of the catalysis with various acidity and porous structure. The low yield of the waxes, when using mordenite and H-ZSM-5 catalysts, was caused by the microporous structure and strong acidic properties of the catalysts resulting in larger amount of gas production. The MCM-41 catalyst modified with various aluminum content raised the wax yield to 60 %. Al-MCM-41(50) produced the largest amount of wax when compared to Al-MCM-41(25), Al-MCM-41(75), and MCM-41. The mild acidity and mesoporous structure of Al-MCM-41(50) significantly enhanced the paraffins structure of the obtained waxes over other structures, while lower Si/Al ratios favored the conversion of paraffins toward olefin structure. The pyrolysis of MLP with Al-MCM-41(50) produced paraffins and olefins with the middle carbon ranging (C11-20) which were similar quality to pharmaceutical grade of petroleum wax. The spent catalysts of Al-MCM-41 series gradually decreased in wax yield and paraffins composition during the sequential MLP pyrolysis; however, the activity of catalysts was recovered after calcination of the spent catalysts. Furthermore, the viscosity of waxes obtained from Al-MCM-41(50) was 2384 Pa.s at 25 °C similar to the viscosity from commercial petroleum jelly base of 2333 Pa.s. [ABSTRACT FROM AUTHOR]

The release of Neogene volcanism in the southeastern part of the Iberian Peninsula produced a series of volcanic structures in the form of stratovolcanoes and calderas; however, other materials also accumulated such as large amounts of pyroclastic materials such as cinerites, ashes, and lapilli, which were later altered to form deposits of zeolites and bentonites. This work has focused on an area located on the northern flank of the San José-Los Escullos zeolite deposit, the only one of its kind with industrial capacity in Spain. The main objective of this research is to characterize the zeolite (SZ) of this new area from the mineral, chemical, and technical points of view and establish its possible use as a natural pozzolan. In the first stage, a study of the mineralogical and chemical composition of the selected samples was carried out using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray fluorescence (XRF), and thermogravimetric analysis (TGA); in the second stage, chemical-qualitative and pozzolanicity technical tests were carried out at 8 and 15 days. In addition, a chemical analysis was performed using XRF on the specimens of mortars made with a standardized mixture of Portland cement (PC: 75%) and natural zeolite (SZ: 25%) at the ages of 7, 28, and 90 days. The results of the mineralogical analyses indicated that the samples are made up mainly of mordenite and subordinately by smectite, plagioclase, quartz, halloysite, illite, and muscovite. Qualitative chemical assays indicated a high percentage of reactive silica and reactive CaO and also negligible contents of insoluble residues. The results of the pozzolanicity test indicate that all the samples analyzed behave like natural pozzolans of good quality, increasing their pozzolanic reactivity from 8 to 15 days of testing. Chemical analyses of PC/SZ composite mortar specimens showed how a significant part of SiO2 and Al2O3 are released by zeolite while it absorbs a large part of the SO3 contained in the cement. The results presented in this research could be of great practical and scientific importance as they indicate the continuation of zeolitic mineralization beyond the limits of the San José-Los Escullos deposit, which would result in an increase in geological reserves and the extension of the useful life of the deposit, which is of vital importance to the local mining industry. [ABSTRACT FROM AUTHOR]

Bio-oil contains many oxygenated compounds, as well as high acid and water content, which can reduce the stability of its components and have poor overall physicochemical properties. In this study, the quality of bio-oil produced from the pyrolysis of oil palm fronds was enhanced through a hydrodeoxygenation (HDO) reaction that was preceded by esterification as a pre-treatment. The catalyst used in the HDO reaction is mixed metal oxide (Fe2O3-CoO) anchored within zeolite mordenite (Fe2O3-CoO/Mor). The catalysts were characterized using XRD, SEM-EDX, and BET methods. The presence of metal oxides on the surface of mordenite increases the activity of the catalyst in producing liquid products while reducing the formation of coke. Upgrading of bio-oil has improved the physicochemical properties of bio-oil compared to the one-stage upgrading process. The analysis of product showed that the C and H content increased from 11.5 to 23.5 wt% and from 9.76 to 11.2 wt%, respectively. On the other hand, the O content decreased from 78.7 to 65.2 wt% with a degree of deoxygenation of 59.8%. Moreover, higher heating value (HHV) of the bio-oil increased by 38% from 11.6 to 16.0 MJ/kg. [ABSTRACT FROM AUTHOR]

In this study, the hydrogen storage properties of various synthetic zeolites, including Zeolite Y (FAU), Mordenite (MOR), ZSM-12 (MTW), and MCM-22 (MWW) are determined at 77 K and atmospheric pressure. The structures of the zeolites are characterized by XRD, ICP-OES, FE-SEM, TGA and N 2 adsorption-desorption isotherms. The results show that H-MCM-22 zeolite has the highest hydrogen storage capacity at 1.0 bar with 1.19 wt%, followed by H-MOR zeolite with 1.05 wt%, H–Y zeolite with 0.75 wt% and H-ZSM-12 zeolite with 0.60 wt%. The hydrogen adsorption data on FAU, MOR, MTW, and MWW at 77 K obey the Sips isotherm model. The experimental data show that the ultra-micropore volume of the zeolite is effective in hydrogen adsorption at low-pressure ranges. In addition, increasing the aluminum content of the zeolite increases the hydrogen adsorption capacity of the zeolite at atmospheric pressure. Therefore, zeolites with channel sizes close to the kinetic diameter of a hydrogen molecule, large cage volumes, and high aluminum content are potential candidates for energy storage applications. [Display omitted] • ZSM-12 and MCM-22 were synthesized and characterized. • The H 2 adsorption capacities of four zeolites were determined at 77 K and 1.0 bar. • The experimental data were analyzed using the Langmuir, Freundlich, and Sips isotherms. [ABSTRACT FROM AUTHOR]

Adsorption properties of sulfurous compounds in natural gases have been studied using clinoptilolite type zeolite catalyst with rich deposits in Azerbaijan. As a result, it was determined that the use of modified clinoptilolite is the most effective based on experimental evidence for the adsorption of H2S, COS and RSH on modified clinoptilolite and NaX zeolite. Based on H2S and COS adsorption heats in modified clinoptilolite, the optimal temperature of regeneration was determined at 250 °C. This is the value of the rate of desorption of sulfur compounds (H2S and COS) from NaX zeolite at 320 °C, determined in industry, in other equal conditions. Thermally modified clinoptilolite is shown to have the best absorption and protective properties. [ABSTRACT FROM AUTHOR]

This work is concerned with classification and study of the composition and properties of hydrothermal zeolites from the Yagodninskoe deposit, (Kamchatka) which were formed in volcanic rocks. The study involved X-ray phase analysis and X-ray fluorescence, optical and scanning electron microscopy. We determined specific syrface AREA the pore size distribution, as well as cation exchange capacity in zeolites. The study resulted in the identification of four main rock types at the deposit: the original unaltered perlites, zeolites rock, zeolitized tuffs, as well as poorly zeolitized tuff breccias. The Content of zeolite group minerals reaches 70%. The minerals mostly include clinoptilolite and, to a lesser degree, mordenite, stilbite, and heulandite. The zeolites are of the alkaline type, with the cation exchange capacity equal to 205.9 mg-equi/100 g. It has been found that these zeolites were mostly formed from perlites and tuff breccias. It is pointed out that the Yagodninskoe zeolites are high quality minerals, and make a promising object of further exploration. [ABSTRACT FROM AUTHOR]

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As the Brønsted acid sites in the 8-membered ring (8-MR) of mordenite (MOR) are reported to be the active center for dimethyl ether (DME) carbonylation reaction, it is of great importance to selectively increase the Brønsted acid amount in the 8-MR. Herein, a series of Fe-HMOR was prepared through one-pot hydrothermal synthesis by adding the EDTA–Fe complex into the gel. By combining XRD, FTIR, UV–Vis, Raman and XPS, it was found that the Fe atoms selectively substituted for the Al atoms in the 12-MR channels because of the large size of the EDTA–Fe complex. The NH3-TPD and Py-IR results showed that with the increase in Fe addition from Fe/Si = 0 to 0.02, the Brønsted acid sites derived from Si-OH-Al in the 8-MR first increased and then decreased, with the maximum at Fe/Si = 0.01. The Fe-modified MOR with Fe/Si = 0.01 showed the highest activity in DME carbonylation, which was three times that of HMOR. The TG/DTG results indicated that the carbon deposition and heavy coke formation in the spent Fe-HMOR catalysts were inhibited due to Fe addition. This work provides a practical way to design a catalyst with enhanced catalytic performance. [ABSTRACT FROM AUTHOR]

Hydrogen sulfide (H2S) is a hazardous gas found in natural gas and biogas, lethal over 100 ppm. When released into the atmosphere, it can turn into sulfur dioxide. One option to remove H2S is using porous materials such as zeolites. Among them, mordenite stands out due to its channel structure, wide availability, and low cost. In this work, we evaluated the H2S adsorption capacity of mordenite using a volumetric static method. The results show the adsorption capacity of H2S in mordenite varies with the exchanged cation. The highest was measured in Na‐mordenite (~4.08 mmol H2S/g mordenite). The experimental breakthrough curves for this zeolite confirmed Langmuir‐type adsorption and strong affinity between Na+ cations and H2S. Despite this interaction, the XRD diffractograms of Na‐mordenite show that the material retained its crystalline structure. More information about the differences in the amount of H2S adsorbed in the zeolites caused by the change in exchanged cation was obtained by H2S adsorption followed by FTIR spectroscopy. The spectra show differences in the position of the peaks related to the different adsorption modes of H2S caused by a change in the polarizing power of the cations due to their charge and position inside the zeolite pores. [ABSTRACT FROM AUTHOR]

The insufficiency of freshwater supplies has posed a serious threat to sustainable socioeconomic growth, and seawater desalination is considered to be the most promising solution to alleviate such pressure. Currently, 2D carbon membranes are identified as deserving candidates due to their high permeability and multiple tunable properties. However, they remain challenging to systematically uncover the potential relationships between structures and properties in various 2D carbon materials. For this, a machine learning (ML) model based on feature datasets of 2D carbon materials effecting desalination properties is trained. The results suggest that structures with a maximum pore size of 10–12 atoms and atomic densities between 0.28 and 0.41 are more likely to achieve high properties. Cml‐MOR based on MOR‐type mordenite zeolite for validation is selected. Further, Cml‐MOR is demonstrated to feature remarkable salt ion adsorption. The effective water flux of Cml‐MOR is 113.51 L cm−2 day−1 MPa−1, and the salt rejection at 110 MPa can reach 98.9%. This work is expected to apply this efficient method to investigate the structure and properties of 2D carbon membranes with great structural diversity; this will attract more people to focus on them and explore their important potential for practical applications. [ABSTRACT FROM AUTHOR]

In this study, pyrazole tartrate (Pya·DL) and tartaric acid (DL) complexed with cobalt–iron bimetallic modified hydrogen-type mordenite (HMOR) were prepared using the ion exchange method. The results demonstrate that the stability of the dimethyl ether (DME) carbonylation reaction to methyl acetate (MA) was significantly improved after the introduction of Pya·DL to HMOR. The Co∙Fe∙DL-Pya·DL-HMOR (0.8) sample exhibited sustainable stability within 400 h DME carbonylation, exhibiting a DME conversion rate of about 70% and MA selectivity of above 99%. Through modification with the DL-complexed cobalt–iron bimetal, the dispersion of cobalt–iron was greatly enhanced, leading to the formation of new metal Lewis acidic sites (LAS) and thus a significant improvement in catalysis activity. Pya·DL effectively eliminated non-framework aluminum in HMOR, enlarged its pore size, and created channels for carbon deposition diffusion, thereby preventing carbon accumulation and pore blockage. Additionally, Pya·DL shielded the Bronsted acid sites (BAS) in the 12 MR channel, effectively suppressing the side reactions of carbon deposition and reducing the formation of hard carbon deposits. These improvements collectively contribute to the enhanced stability of the DME carbonylation reaction. [ABSTRACT FROM AUTHOR]

Adsorption of various glycerol conformations at Brønsted sites in mordenite is studied by the density functional theory. It is shown that the adsorption energy depends on the initial conformation of the glycerol molecule and ranges from –44.0 kcal/mol (ββ conformation) to –64.7 kcal/mol (αγ conformation). In some cases, the glycerol molecule switches its conformation as a result of nanoconfinement. It is shown that the most energetically favorable adsorption of glycerol on mordenite proceeds via the primary OH group. High adsorption energy is due to the proton transfer from the zeolite Brønsted site to glycerol as a result of the hydrogen bond formation and also due to the formation of up to four additional hydrogen bonds with oxygen atoms of the zeolite framework. As a result, the backbone of the adsorbed molecule deforms, which fact should affect the course of chemical reactions involving glycerol. [ABSTRACT FROM AUTHOR]

In this research, upconversion nanocrystals incorporated with MOR zeolite composites were synthesized using the desilicated MOR zeolite as a host for the in situ growth of NaREF4 (RE = Y, Gd) Yb/Er nanocrystals. The structure and morphology of the composites were studied with XRD, XPS, and TEM measurements, and the spectral studies indicated that the subsequent thermal treatment can effectively improve the upconversion emission intensity of Er3+. By using the NaYF4:Yb/Er@DSi1.0MOR-HT composite that holds the strongest upconversion emission, a probe of UCNC@DSiMOR/BPEI was constructed with the modification of branched poly ethylenimine for the detection of Cu2+. It was indicated that the integrated emission intensity of Er3+ shows a linear dependence with the logarithm value of the Cu2+ concentration ranging from 0.1 to 10 μM. This study offered a feasible method for the construction of UCNC@zeolite composites with enhanced upconversion emission, which may have a potential application as fluorescent probes for the detection of various metal ions by adjusting the doping luminescent center. [ABSTRACT FROM AUTHOR]

The Pauzhetka geothermal field was surveyed to study the mineral deposits that were formed as thermal water was discharged from well separators. We studied the compositions, structure, and geochemical properties of these sediments along the flow and in vertical cross sections of manmade "sinters". It was found that, at the beginning of thermal water discharges, the sediments were composed of X-ray-amorphous mordenite–opal mixtures; later on, the sediments became wholly siliceous. The zeolite component of the mineral deposits determines their high sorption properties in relation to Au, Ag, Hg, As, Rb, Sr, Ba, Cs and other elements; the mordenite matrix receives sulfides of iron, silver, and copper. It is shown that the mineral deposits which were formed at the ground surface of the Pauzhetka geothermal field constitute an indicator of alkaline mineral-forming and ore-forming environment in the lower horizons of the Pauzhetka geothermal system. [ABSTRACT FROM AUTHOR]

Mordenite was synthesized at 170 ºC under stirring (60 rpm) with different contents of L-glutamic acid monosodium salt (MSG) between 4 and 48 h. The materials were characterized by XRD, EDX, NH3-TPD, TG/DTG, SEM and N2 physisorption. The catalytic activity of zeolites was evaluated in the n-hexane cracking reaction at 550 ºC for 180 min. Mordenite was obtained with high relative crystallinity (83 ˗ 101%). The insertion of the amino acid salt reduced the acidity of the zeolites from 0.788 to 0.612 mmol g-1. Thermal analyses indicated the complete removal of MSG from the zeolite structure after washing, eliminating the calcination process and consequently, reducing costs. The micrographs revealed crystals of < 10 μm. N2 physisorption isotherms showed an increase in microporosity (SMicro from 411 to 445 m2 g-1 and VMicro from 0.165 to 0.178 cm3 g-1) and a higher degree of mesoporosity (VMeso from 0.009 to 0.012 cm3 g-1) for the samples with the lowest contents of MSG, indicating an optimal range for the addition of amino acid salt. The results of the n-hexane cracking reaction over mordenite samples revealed a higher tendency for the production of light olefins. The Mor/6Glut sample demonstrated high activity and a slower deactivation rate than conventional mordenite, due to the synergy of its lower acidity and mesoporosity. [ABSTRACT FROM AUTHOR]

This research shows the effect of a catalyst supported on mordenite (natural and modified) impregnated with nickel, calcium, and potassium on palm kernel shell gasification for hydrogen production. The gasification process was carried out using a lab-scale fixed bed reactor at 900 °C with steam as gasifying agent. The use of the catalysts significantly improved the hydrogen production and the incorporation of metals in the mordenite increased hydrogen selectivity. The maximum H 2 content in the non-catalyzed gasification was approximately 34 mol%, while in the treatments with catalysts it ranged between 40 and 73 mol%. The T2-C5 catalyst impregnated with Ni, Ca, and K presented the highest H 2 content (72.9 mol%), which is associated with the synergistic interaction of nickel, calcium, and potassium. This catalyst presented the highest strong acidity (1.30 mmol NH 3 g−1) and the highest crystallinity (85.8%) compared to the other catalysts, properties that influenced the catalytic performance. • Synthesis of novel catalysts for H 2 production from biomass gasification. • Catalysts were supported on mordenite with different Ca/Ni, K/Ni and Ca/K/Ni ratios. • Catalysts were characterized with different techniques and used in gasification. • A synergistic effect of Ca, K and Ni favored hydrogen production. • Acidity and crystallinity influenced catalyst performance in the reaction. [ABSTRACT FROM AUTHOR]

Atmospheric air pollution is determined by the functioning of both technogenic and natural sources of pollution. The main anthropogenic sources of pollution are: transport, industrial enterprises, energy facilities and agriculture. In order to select a rational and effective method of atmospheric emissions purification from harmful components, systematic study was carried out to identify the potential of natural zeolites of Georgia. In particular, four samples of zeolite-containing rocks were investigated: analcime, clinoptilolite, phillipsite, mordenite and their modified forms. By means of the chromatographic method of researching the adsorption properties of natural zeolites, the best adsorption capability of mordenite and its modified hydrogen form obtained by two methods towards nitrogen oxides has been revealed. The perspective and profitability of using the hydrogen form of mordenite treated with ammonium in the processes of purification of nitrous gases from exhaust gases is shown, as well as the possibility of using the recovered products (aqueous solutions of ammonium salts) obtained from its regeneration as a nitrogen fertilizer in agriculture. The experimental adsorption purification of the sample (H-mordenite) was carried out in the process of research. The sample was taken from the outlet pipe of the contact apparatus in the ammonia oxidation shop of the nitric acid production enterprise of LLC “Rustavi Azoti”. It has been found that the modified mordenites can be proposed as an environmentally friendly, highly efficient sorbent in the processes of air purification from toxic impurities. Of the two forms of H-mordenite investigated, the adsorption data obtained for NH4+-ion-modified mordenite is approximately 20 % better than the acid-modified form. It should be noted that the use of granulated zeolites (mordenite) in adsorbers with dense packing is very effective. It is also important from the economic point of view that it is possible to reuse spent high-silica sorbents after their regeneration by oxidation method, since such zeolites are resistant to oxidants, such as hydroxyl radicals, ozone, etc., and it is possible to regenerate them without removing them from adsorber. [ABSTRACT FROM AUTHOR]

A series of binder‐free mordenite (MOR) zeolites were successfully prepared by hydrothermal conversion of shaped precursors containing aluminosilicate and MOR seeds. In the synthesis of seed crystals, hexadecyltrimethylammonium bromide (CTAB) was used as a crystal growth inhibitor as well as a pore filler to adjust the morphology and introduce mesoporous pores. As a result, large aggregates, assembled nanosheets, and flowers‐like MOR were successfully synthesized with these MOR seeds. The effect of seed morphology on the performance of the binder‐free MOR was studied by scanning electron microscopy (SEM), N2 adsorption–desorption, and NH3‐TPD characterization techniques. It was found that the mesopore volume of formed MOR was positively correlated with those of the seeds. The synthesized binder‐free MOR showed high activity (0.28 g methyl acetate gcat−1 h−1), 100% selectivity, and high stability in dimethyl ether (DME) carbonylation to methyl acetate, which can be attributed to the larger surface area and more mesopores. The synthesis of MOR nano‐assemblies via this cost‐effective strategy has a wide range of potential applications. [ABSTRACT FROM AUTHOR]

Zeolites are crystalline aluminosilicates that exist naturally, and they are the most common mineral in sedimentary rocks. These minerals are called tectosilicates, and they have an open, three-dimensional structure with the cations required to maintain equilibrium of electrostatic charge between the aluminum framework and silicon tetrahedral units. Most common zeolites are chabazite, clinoptilolite, phillipsite, erionite, stilbite, heulandite, and mordenite. Zeolites are harmless for the environment and living things. Their multipurpose application in agriculture is mainly due to their high porosity, sorption-ion-exchange capability, and welldeveloped specific surface area. Applying zeolites directly to the soil improves its sorption capacity while simultaneously decreasing acidity and boosting nutrient uptake efficiency. Increased yields and less nutrient dispersion in the environment are achieved through better nitrogen utilization from fertilizers. This contributes to the closed-loop economy, the depletion of environmental resources, and the principles of sustainable development. Thus, zeolites have the potential to directly enhance agricultural environments. [ABSTRACT FROM AUTHOR]

Bio-oil from the pyrolysis of palm fronds waste has potential to be used as an alternative fuel. However, due to its poor physicochemical properties, it requires further treatment to improve its overall quality. In this study, the conversion of palm fronds waste into bio-oil was carried out using the semi-fast pyrolysis at 500 °C and continued with esterification and hydrodeoxygenation (HDO). Metal oxides of Cu and Zn with a zeolite carrier mordenite (Mor) were used as bifunctional catalysts in the HDO reaction performed in a fixed-bed system reactor with temperature variations (250, 300, and 350 °C) for 2 h. Upgraded bio-oil (UBO) products at optimum conditions were analyzed for their physicochemical properties. In the pyrolysis process, the highest bio-oil conversion of 46.3% was obtained at a sample size of 60 mesh with the main component of furan compounds (46.31%). In the upgrading process through the esterification pretreatment, the optimum condition of HDO was determined to be at 300 °C, this can be seen from the high yield of liquid phase products produced on each catalyst (Mor; 89.85%, and CuO-ZnO/Mor; 88.25%). The physicochemical properties of upgraded bio-oil obtained under optimum conditions showed an increase in the quality of bio-oil with a decrease in water content (up to 23%), an increase in higher heating value (HHV) (up to 14.67% in CuO-ZnO/Mor). It is known that HDO with CuO-ZnO/Mor catalyst has a higher selectivity than Mor catalyst in converting aromatic hydrocarbon compounds such as methyl cyclohexane which is a potential component of a fuel. [ABSTRACT FROM AUTHOR]

The release of Neogene volcanism in the southeastern part of the Iberian Peninsula produced a series of volcanic structures in the form of stratovolcanoes and calderas; however, other materials also accumulated such as large amounts of pyroclastic materials such as cinerites, ashes, and lapilli, which were later altered to form deposits of zeolites and bentonites. This work has focused on an area located on the northern flank of the San José-Los Escullos zeolite deposit, the only one of its kind with industrial capacity in Spain. The main objective of this research is to characterize the zeolite (SZ) of this new area from the mineral, chemical, and technical points of view and establish its possible use as a natural pozzolan. In the first stage, a study of the mineralogical and chemical composition of the selected samples was carried out using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray fluorescence (XRF), and thermogravimetric analysis (TGA); in the second stage, chemical-qualitative and pozzolanicity technical tests were carried out at 8 and 15 days. In addition, a chemical analysis was performed using XRF on the specimens of mortars made with a standardized mixture of Portland cement (PC: 75%) and natural zeolite (SZ: 25%) at the ages of 7, 28, and 90 days. The results of the mineralogical analyses indicated that the samples are made up mainly of mordenite and subordinately by smectite, plagioclase, quartz, halloysite, illite, and muscovite. Qualitative chemical assays indicated a high percentage of reactive silica and reactive CaO and also negligible contents of insoluble residues. The results of the pozzolanicity test indicate that all the samples analyzed behave like natural pozzolans of good quality, increasing their pozzolanic reactivity from 8 to 15 days of testing. Chemical analyses of PC/SZ composite mortar specimens showed how a significant part of SiO2 and Al2O3 are released by zeolite while it absorbs a large part of the SO3 contained in the cement. The results presented in this research could be of great practical and scientific importance as they indicate the continuation of zeolitic mineralization beyond the limits of the San José-Los Escullos deposit, which would result in an increase in geological reserves and the extension of the useful life of the deposit, which is of vital importance to the local mining industry.

Columnar structures have been exposed by preferential weathering in non-welded, non-vapor-phase-altered zones of the 1.2 to 1.8 Ma Bandelier Tuff ignimbrites around Valles Caldera, New Mexico. These long, largely vertical cylindrical features are similar in composition and texture to the host ignimbrite but represent areas that underwent alteration to make them more resistant to erosion. Analyses show that the column ignimbrite was altered by the addition of the zeolite mordenite as a mineral cement into pore spaces. This, and the presence of illite and, to a lesser extent, chlorite, suggests alteration at ~120–125°C. We map column geometry, spacing, stratigraphic location, and spatial distribution. Columns are mostly vertical, there is a correlation between the diameters and spacing, and they exist in linear to rounded clusters of a few to 30 columns. Based on the location within the ignimbrites, the shape and form of column groups, and the temperature of formation of the columns, we propose that slumping of over-steepened valley walls exposed friable, warm, unaltered ignimbrite that enabled ponded meteoritic water to permeate into the deposit, which allowed localized convective chimney cells to form. We develop an analytical model to show that infiltrating water is convectively unstable, and, for reasonable permeabilities, we can explain the observed column spacing and alteration temperature. This model permits columns to form within parts of the deposits perched in ignimbrite deposited against pre-existing valley walls. An abundant supply of water from high precipitation is implied, reflecting a syn-glacial, pluvial climate in the southwestern United States at that time (1–2 Ma ago).

The adsorption, temperature-programmed desorption, and carbonylation of dimethyl ether (DME) in the presence of mordenite and ferrierite (SiO2/Al2O3 ≈ 20, Zeolyst International) is studied. The effect of introducing Cu, Co, and Mg cations by ion exchange is discussed. Dimethyl ether carbonylation is conducted at 200°С, a pressure of 3 MPa, and a space velocity of 8000 mL g–1 h–1 in the following mixture (vol %): DME, ⁓2.2; CO, 92.8–95.5; and the rest, N2. After an induction period, the methyl acetate content in the presence of mordenite is about 4–5 times higher than that in the presence of ferrierite. Water, methanol, and hydrocarbons are formed in trace amounts. The introduction of Cu, Co, and Mg cations into mordenite by ion exchange (single ion-exchange run, cation/Al ratio of no more than 35%) leads to an increase not only in stability, but also in activity in the DME carbonylation reaction. It is found that an increase in the content of copper (from 1.19 to 2.23 wt %) and magnesium (from 0.62 to 1.8 wt %) has different effects on activity. It increases in the case of copper and decreases in the case of magnesium. The prereduction of a copper-exchanged mordenite leads to the appearance of metallic copper particles on the surface of the mordenite crystallites and a decrease in activity. According to in situ diffuse reflectance infrared spectroscopy, the introduction of magnesium cations by three ion-exchange runs leads to a significant decrease in the number of Brønsted acid sites (BASes) in both the 12-MR and 8-MR channels of the mordenite. The catalytic characteristics of ferrierite hardly change upon the introduction of copper and magnesium by ion exchange. [ABSTRACT FROM AUTHOR]

A study is performed to establish the main factors that allow regulation of the activity and selectivity of the synthesis of solketal from glycerol and acetone, and the acidic and catalytic properties of mordenite zeolites (MOR, SiO2 : Al2O3 = 29.2) and faujasite (FAU, SiO2 : Al2O3 = 14.9; 97 and 810). The reaction is studied in a methanol solution at an acetone : glycerol molar ratio of 2.5 and a temperature of 25–50°C. Using zeolites, the main product is solketal with a selectivity of 88.1–94.7%. It is shown that the main factors determining the conversion of glycerol and the yield of solketal are the accessibility of the reagents to active sites, the number and strength of acid sites, and their resistance to the toxic action of water molecules that form during the reaction. [ABSTRACT FROM AUTHOR]

Here, we report the results of our 1H nuclear magnetic resonance study of the dynamics of water molecules confined in zeolites (mordenite and ZSM-5 structures) with hierarchical porosity (micropores in zeolite lamella and mesopores formed by amorphous SiO2 in the inter-lamellar space). 1H nuclear magnetic resonance (NMR) spectra show that water experiences complex behavior within the temperature range from 173 to 298 K. The temperature dependence of 1H spin-lattice relaxation evidences the presence of three processes with different activation energies: freezing (about 30 kJ/mol), fast rotation (about 10 kJ/mol), and translational motion of water molecules (23.6 and 26.0 kJ/mol for pillared mordenite and ZSM-5, respectively). For translational motion, the activation energy is markedly lower than for water in mesoporous silica or zeolites with similar mesopore size but with disordered secondary porosity. This indicates that the process of water diffusion in zeolites with hierarchical porosity is governed not only by the presence of mesopores, but also by the mutual arrangement of meso- and micropores. The translational motion of water molecules is determined mainly by zeolite micropores. [ABSTRACT FROM AUTHOR]

BACKGROUND: Grand efforts have been recently devoted to the development of catalysts based on the excellent performance of Cu‐ and Fe‐dependent enzymes in methanotrophic bacteria for the partial oxidation of methane to methanol under ambient conditions. As a continuation of the study on the stepwise manner for this conversion over zeolite‐based catalysts, in this work, the effects of zeolite topology and activation temperature on the catalytic performance of Cu‐ and Fe‐containing zeolites were investigated. RESULTS: Cu species exchanged in the medium‐pore zeolites (mordenite, ZSM‐5, and ferrierite) afforded better methanol production, while large‐pore zeolites (zeolite β and zeolite γ) were inappropriate to accommodate active Cu sites. Notably, Cu/silicalite‐1 containing CuO species was also reactive to methane after the activation in O2, yielding a minor methanol amount. Furthermore, the activity of Fe/mordenite towards the methanol in the O2‐assisted procedure was reported for the first time but with a much lower yield as compared to that of Cu/mordenite. The methanol yield over Cu/mordenite increased with the activation temperature because increasing the activation temperature favored the Cu‐exchange degree with a higher priority at the side pockets as compared to the main channels of mordenite, as evidenced from infrared analysis. CONCLUSION: The selective oxidation of methane to methanol by O2 via a stepwise manner can be obtained over both ion‐exchanged Cu species and well‐dispersed CuO nanoparticles with better activity being recorded for the former. The activity of Cu‐exchanged zeolites was considerably dependent on the zeolite topology and the charge‐balancing position of the Cu2+ cations. © 2023 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

Copper(II)‐containing mordenite (CuMOR) is capable of activation of C−H bonds in C1‐C3 alkanes, albeit there are remarkable differences between the functionalization of ethane and propane compared to methane. The reaction of ethane and propane with CuMOR results in the formation of ethylene and propylene, while the reaction of methane predominantly yields methanol and dimethyl ether. By combining in situ FTIR and MAS NMR spectroscopies as well as time‐resolved Cu K‐edge X‐ray absorption spectroscopy, the reaction mechanism was derived, which differs significantly for each alkane. The formation of ethylene and propylene proceeds via oxidative dehydrogenation of the corresponding alkanes with selectivity above 95 % for ethane and above 85 % for propane. The formation of stable π‐complexes of olefins with CuI sites, formed upon reduction of CuII‐oxo species, protects olefins from further oxidation and/or oligomerization. This is different from methane, the activation of which proceeds via oxidative hydroxylation leading to the formation of surface methoxy species bonded to the zeolite framework. Our findings constitute one of the major steps in the direct conversion of alkanes to important commodities and open a novel research direction aiming at the selective synthesis of olefins. [ABSTRACT FROM AUTHOR]

To achieve a better catalytic performance, it is of great interest to synthesize nanosized zeolites with reduced internal diffusion limitations. Herein, c-axis shortened wheel-like mordenite nanoassemblies were synthesized. The crystal growth along the [001] direction was successfully inhibited with K+ cations as structure breaking agents. The wheel-like crystal is 1.5–2 μm in diameter and 200–300 nm in thickness. The growth of such a unique structure underwent a nonclassical crystallization process including the generation of amorphous worm-like particles and formation of wheel-like crystallites followed by a–b plane oriented growth of the crystals. The obtained MOR wheel-like assemblies possessed larger surface area and external surface area, displayed better mass transfer properties, and exhibited much better catalytic performance than MOR spheroid-like assemblies and conventional bulk MOR zeolite in dimethyl ether (DME) carbonylation reaction, with two and a half times higher the conversion of DME than the bulk MOR, although these samples had identical Si/Al ratios and acid properties. This work provides a simple route to control the zeolite morphology by alkali metal cations and brings forward an effective strategy to prepare zeolite materials with improved catalytic performance. [ABSTRACT FROM AUTHOR]

Nitrogen oxides (NOx), which result from the decomposition of nitrocellulose (NC)-based solid propellants, promote the degradation of this later and alter its long-term stability. Thus, to avoid such situation and ensure a better stability, conventional stabilizers such as aromatic amines or urea compounds are usually added to the NC-based formulations. However, these latter may generate carcinogenic and toxic species that may negatively affect both human health and environment. Herein, based on its selective adsorption capacity of NOx, the stability potential of a porous inorganic compound, namely, mordenite (MOR), on nitrocellulose was assessed. Three NC-based samples (S1–S3) were prepared through the incorporation of 3 wt.% of stabilizing agents, i.e., S1: pure NC, S2: NC + DPA, and S3: NC + MOR. The effect on the stability of this inorganic compound with regard to pure NC has been highlighted utilizing stability tests and kinetic modeling. Beforehand, the compatibility of mordenite with nitrocellulose was initially checked by means of DSC and FTIR. Furthermore, the obtained results via Vacuum Stability Test (VST) and Bergmann–Junk (B&J) test demonstrated that S3 displayed a better stability than S1 and comparable behavior to S2. The determination of the kinetic triplet by isoconversional methods confirmed the effectiveness of MOR as a stabilizing agent. These findings claim that such inorganic compound may be used efficiently as a stabilizer for NC-based energetic formulations. [ABSTRACT FROM AUTHOR]

Veratryl alcohol (VA) is preferentially oxidized to veratraldehyde (VADE) using a heterogeneous catalyst, which is more favoured in industries. Commercial mordenite (Ca,Na2,K2) Al2Si10O24·7H2O) was desilicated with NaOH and loaded with nickel and iron bimetal by the wet impregnation method. The synthesised Mordenite-Fe(5 %)/Ni(5–20 %) bimetallic catalyst, possessing active Bronsted acid sites, was employed to selectively oxidize the veratryl alcohol reaction. FT-IR, XRD, BET, HR-SEM, HR-TEM, and TPD were employed to determine the catalyst's textural attributes, morphology, chemical properties, and stability. Selective oxidation was performed over the catalysts using TBHP as an oxidant in a continuous reactor. To examine the most active catalyst among the four and to maximise the conversion and yield, the reaction conditions are optimised for various reaction parameters The reaction conditions were optimized by attaining 100 % conversion at temperature (90° C) for time (2 hr) and a maximum conversion of 97 % and a selectivity of 99 % at 10 bar pressure, WHSV (1.0 h−1) with acetonitrile solvent. The result of the study display that Fe (5 %) and Ni(15 %) impregnated on mordenite exhibits excellent catalytic stability with conversion (100 %) and selectivity (99 %) among the other catalysts. During regeneration, the conversion rate declined from 99.5 to 92.4.7 % and selectivity declined from 100 % to 96.2 % at the end of the seventh cycle. The high selectivity and stability of MOR-Fe(5 %)/Ni(15 %) imply that they might function properly as appropriate catalysts for the oxidation of aromatic alcohols. The advantages of the current synthesis are its cost-efficiency and eco-friendliness.

The potential of Georgian natural Mordenite has been studied as a low-cost, eco-friendly adsorbent for the removal of lead ions (Pb(II)) from aqueous solutions in various experimental environments. The natural and modified Mordenite structural characterization was carried out using XRD, SEM-EDS, and XRF, methods. The following parameters were studied for adsorption: dependence of solution pH, adsorbent dose, and initial concentration of lead (II) ions. The results of the optimization study showed that a high dose of adsorbent and a low concentration of Pb (II) ion increase the sorption. The optimum pH was found to be 6-8. Sorption capacity increased along with pH. Langmuir and Freundlich isotherms were used to model the adsorption data. Correlation coefficient values (R2) were 0.975 and 0.922, respectively. Isotherm studies showed that the uptake equilibrium is best described by the Langmuir adsorption isotherm. The maximum sorption capacity was found to be 11.439 mg/g. The research results showed that natural Georgian Mordenite can be used to remove Pb (II) ions from aqueous solutions.

Abstract This work examines the impact of mordenite-rich tuff (MT) on the technological properties of fired clay brick. These specimens were obtained by substituting clay with MT in various proportions (0, 5, 10, 15, 20, 50, and 100 wt%). They were pressed at 10 MPa, air-dried in the laboratory, and fired at 900 °C using two different clays: clay of Remila (CR) and clay of Adjiba (CA), Algeria. The mechanical, thermal, and physical properties of fired bricks were determined and compared to those of control bricks (0 wt%). According to the finding, the partial and total substitution of clay by MT reduced the sample’s thermal conductivity and bulk density. Thus, the MT increased the apparent porosity and the water absorption of clay brick while maintaining the compressive strength within the limits of the Algerian standards. This research revealed the possibility of producing bricks containing up to 100% by weight of MT with the required technical and environmental properties.

As the Brønsted acid sites in the 8-membered ring (8-MR) of mordenite (MOR) are reported to be the active center for dimethyl ether (DME) carbonylation reaction, it is of great importance to selectively increase the Brønsted acid amount in the 8-MR. Herein, a series of Fe-HMOR was prepared through one-pot hydrothermal synthesis by adding the EDTA–Fe complex into the gel. By combining XRD, FTIR, UV–Vis, Raman and XPS, it was found that the Fe atoms selectively substituted for the Al atoms in the 12-MR channels because of the large size of the EDTA–Fe complex. The NH3-TPD and Py-IR results showed that with the increase in Fe addition from Fe/Si = 0 to 0.02, the Brønsted acid sites derived from Si-OH-Al in the 8-MR first increased and then decreased, with the maximum at Fe/Si = 0.01. The Fe-modified MOR with Fe/Si = 0.01 showed the highest activity in DME carbonylation, which was three times that of HMOR. The TG/DTG results indicated that the carbon deposition and heavy coke formation in the spent Fe-HMOR catalysts were inhibited due to Fe addition. This work provides a practical way to design a catalyst with enhanced catalytic performance.

The potential of Georgian natural Mordenite has been studied as a low-cost, eco-friendly adsorbent for the removal of lead (II) ions from aqueous solutions in various experimental environments. The natural and modified Mordenite structural characterization was carried out using XRD, SEM-EDS, XRF, methods. The following parameters were studied for adsorption: dependence of solution pH, adsorbent dose, and initial concentration of lead (II) ions. The results of the optimization study showed that a high dose of adsorbent and a low concentration of Pb (II) ion increase the sorption. The optimum pH was found to be 6-8. Sorption capacity increased along with pH. Langmuir and Freundlich isotherms were used to model the adsorption data. Correlation coefficient values (R2) were 0.975 and 0.922, respectively. Isotherm studies showed that the uptake equilibrium is best described by the Langmuir adsorption isotherm. The maximum sorption capacity was found to be 11.439 mg/g. The research results showed that natural Georgian Mordenite can be used to remove Pb (II) ions from aqueous solutions. [ABSTRACT FROM AUTHOR]

Mordenite's excellent physical and chemical qualities set it apart from other zeolites with similar applications in industry. Mordenite is frequently produced through hydrothermal processing with TEA+ cations. The best template agent is TEA+ cations, despite the fact that they may lead to a variety of problems, such as the release of toxicity, the high cost of production, the contamination of wastewater, and environmental damage. So, it's important to develop a mordenite synthesis technique that doesn't need an organic template or a cheap template. The mordenite-type zeolites were prepared using sand from the western part of Iraq (Ar-Rutbah). Silica was extracted from Iraqi sand as a silica source and sodium aluminate as a source of alumina Al by using the SOL-GEL method through the hydrothermal technique at temperatures ranging from 23 to 27 °C over a period of 7 days. Analyses such as XRD, BET surface area AFM, FT-IR, and FE-SEM were performed on the sample. The average particle size was 31.9 nm, and the BET surface area was 202.487. XRF detected the ratio of silica to alumina (Si/Al = 4.55), and the exchange of sodium ions for hydrogen ions through ionic exchange is 100%. The micrograph clearly reveals a tiny portion of the crystal band with a flaky habit, while FE-SEM images of synthesized H-MOR show that plates form the majority of the crystals. [ABSTRACT FROM AUTHOR]

The natural zeolites were ultrasonically treated and impregnated with silver nanoparticles. The surface stabilized silver nanoparticles dispersion was obtained using an effective electrochemical reduction method. The phase and elemental composition, structure of the Ag-impregnated zeolites (clinoptilolite and mordenite) was studied by various methods such as powder X-ray diffraction, X-ray fluorescence analyses and Fourier-transform infrared spectroscopy. The Ag-impregnated clinoptilolite and mordenite natural zeolite materials with 1.20 wt %, 0.97 wt %, 0.83 wt % and 1.18 wt % silver content were established by XRF analysis. As initial materials were used three types clinoptilolite from Beli Plast, Most, Golobradovo (Kardzhali, Bulgaria) deposits and mordenite from Lyaskovets deposit in Eastern Rhodopes, Bulgaria. The catalytic ability of Ag-mordenite and Ag-clinoptilolites was investigated in the ecologically important reaction of ozone decomposition. The Ag-loaded mordenite demonstrates the higher conversion degree of ozone more than 40% in comparison with Ag-clinoptilolite materials at room temperature. [ABSTRACT FROM AUTHOR]

Cu‐exchanged mordenite (MOR) is a promising material for partial CH4 oxidation. The structural diversity of Cu species within MOR makes it difficult to identify the active Cu sites and to determine their redox and kinetic properties. In this study, the Cu speciation in Cu‐MOR materials with different Cu loadings has been determined using operando electron paramagnetic resonance (EPR) and operando ultraviolet‐visible (UV/Vis) spectroscopy as well as in situ photoluminescence (PL) and Fourier‐transform infrared (FTIR) spectroscopy. A novel pathway for CH4 oxidation involving paired [CuOH]+ and bare Cu2+ species has been identified. The reduction of bare Cu2+ ions facilitated by adjacent [CuOH]+ demonstrates that the frequently reported assumption of redox‐inert Cu2+ centers does not generally apply. The measured site‐specific reaction kinetics show that dimeric Cu species exhibit a faster reaction rate and a higher apparent activation energy than monomeric Cu2+ active sites highlighting their difference in the CH4 oxidation potential. [ABSTRACT FROM AUTHOR]

Micro-mesoporous Mordenite and ZSM-5 zeolites with tailor-made pore structures are produced using post-synthetic dealumination and desilication treatment. Inductively coupled plasma–optical emission spectroscopy (ICP-OES) analysis showed that post-synthetic acid and base treatment resulting into tuning the Si/Al ratio, thereby increasing the acidity of sample. Acidic characteristics of the samples were confirmed using pyridine FTIR and NH3− TPD. Acetic acid was converted to benzyl acetate by reacting with benzyl alcohol, over both hierarchical samples and their parent counterparts. Acid-modified zeolites were compared with those of base-modified one and also with the unaltered parent materials. Mesoporous pore volume of all zeolites significantly increased due to base alteration compared to the acid alteration and the parent samples. In other studies, the micro-/meso-H-ZSM-5 catalyst showed considerable potential for benzylation, exhibiting an impressive AA conversion rate of 94% with 95% benzyl acetate selectivity. In comparison, in the current study, an alternative catalyst consisting of base-altered Mordenite was found to surpass these results, achieving a 100% AA conversion and 98.2% selectivity towards benzyl acetate. Optimization of the process was investigated by altering time, temperature and catalyst amount. Analysis of reaction products was validated by GC and GC–MS. The reaction rate constants exhibited a positive correlation with increasing reaction temperature, as per the principles of first-order reaction kinetics (R2 > 0.94); and activation energy for AA benzylation over Mor-0.1 M NaOH was found to be 13.87 kJ mol−1, which is significantly lower than the previously reported value. [ABSTRACT FROM AUTHOR]

In this contribution, the formation and growth of coke and its consequences on the mordenite catalyst were investigated on microbalance, through the transformation of propene at 350 °C. The kinetic results revealed that a higher initial coking activity leads to faster initial deactivation and there is a proportionality between the rate of coke formation and the rate of its deactivation. The increase of propene pressure supports the rate of coke formation rather than its growth to heavier and more aromatic molecules. This self-deactivation results from the inhibition of Brønsted acid sites predominantly by pore blockage. Combining the residual acidity and coke composition data makes it possible to estimate the contribution of pore blocking and site poisoning. These two deactivation modes are related and occur simultaneously. [ABSTRACT FROM AUTHOR]

The thermal power plants produce huge quantity of fly ash as waste materials, and dumped in to the ash dykes, which occupies several acres of land and ultimately, spoil it. Researchers are looking for the reasonable treatment process to convert the fly ash into useful materials like zeolites. In this work, fly ash derived Mordenite zeolite has been synthesized with improved catalytic activity. The utility of this material is demonstrated as a solid acid catalyst for the synthesis of n-butyl levulinate from biomass derived levulinic acid. This study demonstrates successful cost effective transformation of fly ash into environmentally benign catalyst.

As clean energy, methane has huge reserves and great development potential in the future. Copper zeolites are efficient in the oxidation of methane to methanol. Water has been confirmed as a source of oxygen to regenerate the copper-zeolite active sites to enable selective anaerobic oxidation of methane to methanol. In this work, we report that the methanol yield increased from 36 μmol/g (Cu-MOR1) to 92 μmol/g (Cu-MOR1-water) as a result of water enhancing the activity of copper ion-exchange mordenite catalyst. We show for the first time that water could convert inactive copper species into active copper species during catalyst activation. A combination of the XPS, FTIR, and NMR results indicates that water dissociates and then converts ZCuIIZ into ZCuII(OH) (where Z indicates framework O (Ofw) bonded to one isolated Al in a framework T-site, i.e., 1Al) and simultaneously produces a Brönsted acid site during catalyst activation. This finding can be used to tune the state of copper species and design highly active copper-zeolite catalysts for methane oxidation to methanol. [ABSTRACT FROM AUTHOR]

The carbonylation of dimethyl ether (DME) to produce methyl acetate (MA) has a promising prospect in industry. Mordenite (MOR) has been widely studied due to its excellent catalytic activity and high MA selectivity; however, its microporous characteristic limits the intracrystalline diffusion that influences the activity and stability. Therefore, it becomes essential to clarify the relationship between catalytic activity and diffusion. In this study, a series of MOR samples with similar Si/Al contents and aspect ratios, but different sizes, were successfully synthesized by adjusting the synthesis parameters (Si/Al contents in gel, aging time, the amount of water, and alkalinity). Based on quantitative analysis of acid properties and catalyst evaluation, both the apparent turnover frequency of MA (TOFMA) and the stability decrease with the increase in particle size. Diffusion parameter measurements and kinetic analysis via zero length column methods show that the intracrystalline diffusion restriction becomes more serious with increasing particle size. The larger the MOR crystals with enhanced mass transfer limitation that undergo lower activity, the higher the selectivity of byproducts, as well as the faster their deactivation. [ABSTRACT FROM AUTHOR]

The adsorption of two model dyes, methylene blue (MB) and Acid Red 97 (AR97), onto mordenite was examined in this study using an experimental design method. They used response surface modeling and a Box-Behnken surface statistical design to optimize the removal of dyes from aqueous solutions. Solution pH, the quantity of dyes, and the dose of mordenite were the three factors taken into consideration. The study discovered that the adsorption of methylene blue was significantly influenced by solution pH, with pH 10 having the best adsorption effectiveness. In contrast, pH 3 was discovered to be the ideal setting for Acid Red 97. Additionally, the scientists discovered that both dyes experienced chemisorption, which is a chemical reaction between the dye and the surface of the mordenite. The study also looked into how time, dosage, and pH affected the adsorption procedure. Further research into the impact of temperature revealed that higher temperatures resulted in greater adsorption effectiveness. The adsorption process for both dyes was endothermic and spontaneous, which is compatible with thermodynamic principles, which contend that chemical reactions are more likely to occur at higher temperatures. Compare the adsorption outcomes with various adsorbents. It was discovered that AR97 and MB had the best adsorption rates, respectively, of 1,212.76 mg and 559.8 mg/g. Overall, the study offers insightful information about the adsorption of dyes onto mordenite and emphasises the significance of taking a number of variables into account when designing an adsorption process, including solution pH, temperature, and dose. [ABSTRACT FROM AUTHOR]

Mordenite (MOR)/PTFE Nafion composite membranes were produced by impregnating Nafion solutions in a PTFE porous support with a modified form of MOR. A 3-mercaptopropyl triethoxysilane (MPTES) - MOR mixture is used as a filler in the PTFE Nafion membrane to block methanol crossover and increase water uptake. An experiment was conducted with a membrane without M-MOR (PTFE Nafion membrane) and a membrane with M-MOR at 2, 4, and 10 wt% (2-, 4-, and 10-M-MOR/PTFE Nafion membranes, respectively). In order to improve the interfacial properties, surface modification of the zeolite was conducted with a silane coupling reaction. The MOR samples were analyzed by SEM, SEM-EDS, and BET surface area analysis. The Nafion membrane was analyzed by SEM, according to the water uptake, and by an electrochemical analysis. The 10-M-MOR/PTFE Nafion membrane showed greater water uptake of 75% compared to the PTFE Nafion membrane without M-MOR (28%). It was found that the addition of MOR had a positive effect on the reduction of the methanol permeability of the MOR/PTFE Nafion membrane. The DMFC (Direct Methanol Fuel Cell) power density of MEA with the 4-M-MOR/PTFE Nafion membrane (4-M-MOR MEA) was found to be 71% higher than that of the PTFE Nafion membrane (0-M-MOR MEA). 1), International Journal of Hydrogen Energy, Effects on the electrochemical performance of surface-modified mordenite in a PTFE Nafion composite membrane for direct methanol fuel cells, Gyu-Na Bae, Hye-Won Kim, Eun-Mi Jung, Sungmin Kang, Yong-Gun Shul, Dong-Hyun Peck. [Display omitted] • Modified mordenite (MOR)/PTFE Nafion composite membranes were produced by impregnating Nafion solutions in a PTFE support. • It was found that the addition of MOR had a positive effect on the reduction of the methanol permeability. • The maximum power density of the 4-M-MOR MEA for DMFC was 71% higher than that of the 0-M-MOR MEA. [ABSTRACT FROM AUTHOR]