Mordenite Zeolite Research Articles

Modulating acid sites in Y zeolite for valorisation of furfural to get γ-valerolactone.

Furfural is a biomass-derived platform molecule that can be converted into a variety of useful products. Catalysts having appropriate balance between Lewis and Brønsted acid sites are suitable for valorisation of furfural. Lewis acidic metal ion incorporated zeolites were studied for this purpose. However, incorporating Lewis acidic metal ions into an alumino-silicate framework of a zeolite is a cumbersome process. Hence, an attempt has been made in this work to modulate the acid sites of Y zeolite via thermal treatment to effect controlled dealumination and use it for valorisation of furfural using isopropyl alcohol, which is a cascade transformation. The thermal treatment of zeolites changed the distribution of acid sites and increased the weak plus moderate to strong acid site ratio. Among the thermally dealuminated Y, beta and mordenite zeolites, with SiO2/Al2O3 ratio 5.2, 25 and 20, only Y zeolite could yield γ-valerolactone, the final product of the aimed cascade transformation. Complete conversion of furfural and 52% γ-valerolactone yield could be achieved under the optimized conditions using NH4Y zeolite thermally dealuminated at 700 °C (TY700). The better catalytic activity of TY700 could be correlated to a combination different factors such as framework structure, suitable weak plus moderate to strong acid site ratio, presence of both penta-coordinated and octahedral Al sites and balance between Brønsted and Lewis acid sites.

Kinetic, Spectroscopic, and Theoretical Study of Toluene Alkylation with Ethylene on Acidic Mordenite Zeolite

Kinetic, Spectroscopic, and Theoretical Study of Toluene Alkylation with Ethylene on Acidic Mordenite Zeolite

Carbonylation of dimethyl ether in mordenite using Inelastic Neutron Scattering

Zeolite mordenite (MOR, Si/Al = 10) was used as catalyst for the reaction between CO and dimethyl ether (DME) to give methyl acetate. Since the reaction is catalysed by Brønsted acid sites, Inelastic Neutron Scattering (INS) is an appropriate technique to identify the intermediates. Although the accepted mechanism goes through an adsorbed methoxy, its characteristic peak at 963 cm−1 was only detected in the reaction MOR + DME, in the absence of CO. When CO is present, the peak at 963 cm−1 is substituted by other peaks that give valuable information of the reaction intermediates, indicating that either methoxy intermediates are not formed or are quickly replaced by the acetyl intermediate, [SiO(COCH3)Al], strongly stabilised in the micropore pockets of mordenite. Upon reaction of MOR + CO + DME, a characteristic peak at 1050 cm−1, although being present in liquid methyl acetate, could not be assigned to adsorbed methyl acetate since it loses intensity as the reaction proceeds (upon heating), and was assigned to a strong interaction between CO and DME adsorbed in one or two Brønsted sites, leading to some intermediate that shares this vibrational feature with methyl acetate in liquid phase. Finally, a peak at 1275 cm−1 in the spectrum of MOR + CO + DME upon heating is assigned to the formation of methyl acetate when the sample is heated, corresponding to C–O stretching of methyl acetate. This is further confirmed by the absence of this peak before heating. Overall, INS technique has allowed an accurate determination and interpretation of peaks involved in the carbonylation of DME in mordenite.

Synthesis and application of Pt-containing catalysts based on mordenite zeolite and natural halloysite nanotubes in the gas-phase isomerization of C-8 aromatic fraction

The MOR-type zeolite was synthesized by a template-free method using natural aluminosilicate halloysite nanotubes (HNT) as a hard template and a source of aluminum and silicon. Samples were studied using a complex of physicochemical methods of analysis: XRD, TEM, N2 physisorption, NH3-TPD and XRF. Specific BET surface area of MOR prepared using HNT is 306 m2/g, mesopores in the MOR:HNT accounted for 30 % of the total pore volume. Based on the synthesized materials (MOR, MOR:HNT and MOR + HNT), Pt-containing catalysts were prepared. The catalysts were investigated in the gas-phase isomerization of C-8 aromatic fraction in a temperature range of 360–420 °C, varying LHSV from 2 to 6 h−1, at H2 pressure of 1 MPa and hydrogen/feedstock volume ratio of 900 nl/l. The prepared catalysts demonstrated strong activity in ethylbenzene transformation (more than 95 %), while providing a high yield of p-xylene (more than 95 % of thermodynamic value).

Effect of seed on synthesis of binder‐free mordenite for dimethyl ether carbonylation

AbstractA 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.

Modification and characterization of Mordenite zeolite derived from waste coal fly ash and its application as a heterogeneous catalyst for the n-butyl levulinate synthesis

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.

Atomic and Electronic Structures on a Mordenite Zeolite

Atomic and Electronic Structures on a Mordenite Zeolite

Designing mordenite zeolites with tunable distribution of acid sites in channels and nano-morphology to boost the catalytic behavior performance of dimethyl ether carbonylation

Mordenite (MOR) zeolite is an efficient catalyst for dimethyl ether (DME) carbonylation, which a key step of indirect production of ethanol from syngas. Herein, a nanosheets MOR zeolite with an ultrathin thickness of 10–30 nm can be facilely synthesized by using a commercial cetyltrimethylammonium hydroxide agent. It greatly shortened the pore length of 8-membered ring (8-MR) side pocket and more amount of Brønsted acid sites (BAS) can be exposed. More importantly, the amount of BAS in 8-MR side pockets of the MOR zeolite can be significantly increased. It should be noted that the morphology of MOR zeolite with prismatic, nanosheets, and petal-like can be obtained and precisely regulated. As a result, the conversion of DME over the nanosheets MOR zeolite is increased by nearly 2 times. Our finding proposed a novel strategy for constructing tunable nanosized morphology MOR zeolite and simultaneously directional enrichment of BAS in 8-MR channels.

Enhancement of the dimethyl ether carbonylation activation via regulating acid sites distribution in FER zeolite framework

The carbonylation of dimethyl ether (DME) with CO is a key step for ethanol synthesis from syngas, but traditional mordenite (MOR) zeolite shows low catalytic stability. Herein, various FER zeolite nanosheets were prepared with four types of organic templates. The catalytic performance of FER in DME carbonylation is strongly dependent on the location of strong acid site in framework, which can be effectively regulated by altering organic template. FER-MORP sample synthesized with morpholine shows the highest DME conversion of 53%, thus, giving a methyl acetate space-time yield (STYMA) of 0.889mmol g-1 h-1. DFT calculation, NH3-IR, 1H/27Al/29Si MAS NMR, and in situ DRIFTS results indicate that morpholine directs more Al species, or strong Brønsted acid sites (BAS), to locate in 8-membered ring (8-MR) channels, which not only enhances carbonylation activity but also suppresses formation of coke species. The catalytic performance is well maintained within 4 repeated recycles (∼460 h).

Speciation and Reactivity Control of Cu-Oxo Clusters via Extraframework Al in Mordenite for Methane Oxidation.

The stoichiometric conversion of methane to methanol by Cu-exchanged zeolites can be brought to highest yields by the presence of extraframework Al and high CH4 chemical potentials. Combining theory and experiments, the differences in chemical reactivity of monometallic Cu-oxo and bimetallic Cu-Al-oxo nanoclusters stabilized in zeolite mordenite (MOR) are investigated. Cu-L3 edge X-ray absorption near-edge structure (XANES), infrared (IR), and ultraviolet-visible (UV-vis) spectroscopies, in combination with CH4 oxidation activity tests, support the presence of two types of active clusters in MOR and allow quantification of the relative proportions of each type in dependence of the Cu concentration. Ab initio molecular dynamics (MD) calculations and thermodynamic analyses indicate that the superior performance of materials enriched in Cu-Al-oxo clusters is related to the activity of two μ-oxo bridges in the cluster. Replacing H2O with ethanol in the product extraction step led to the formation of ethyl methyl ether, expanding this way the applicability of these materials for the activation and functionalization of CH4. We show that competition between different ion-exchanged metal-oxo structures during the synthesis of Cu-exchanged zeolites determines the formation of active species, and this provides guidelines for the synthesis of highly active materials for CH4 activation and functionalization.

Post-synthetically modified hierarchical Mordenite and ZSM-5 zeolite and their catalytic performances in benzylation of acetic acid to benzyl acetate

Post-synthetically modified hierarchical Mordenite and ZSM-5 zeolite and their catalytic performances in benzylation of acetic acid to benzyl acetate

Coke toxicities, descriptors of the deactivating effect of coke on microporous and desilicated mordenite zeolite

Coke toxicities, descriptors of the deactivating effect of coke on microporous and desilicated mordenite zeolite

Zeolitization of a devitrified high-silica rhyolitic tuff producing dachiardite: A comparison of hydrothermal experiments with the corresponding reaction progress modeling

We have investigated the hydrothermal alteration of polished wafers of tuff reacted with dilute groundwater at 90 °C, 150 °C and 250 °C for time periods ranging from 2 months to nearly 1 year. The polished rock wafer provided a convenient surface upon which to grow secondary minerals. Reaction product minerals were identified and analyzed at the end of each experiment and, along with the evolving fluid chemistry, were compared to computational results from corresponding reaction progress models.At 250 °C after a few months the run products in the experiment were dominantly the mordenite group zeolite minerals: dachiardite (a Ca-rich variety) and mordenite, itself. At 150 °C after a few months of reaction only minor amounts of clay were produced, but after 1 year of reaction at this temperature both mordenite group zeolites were again present. At this lower temperature the total amount of run products was much smaller. At 90 °C no run products could be seen at all, even after 1 year of reaction. The reaction progress modeling results for reaction products were in good relative agreement with the experimental results.The higher the temperature, and the greater the extent of reaction, the better the fluid phase modeling results agreed with the actual experimental results. At 250 °C the agreement was good for nearly all elements. At 150 °C agreement for pH, SiO2, Na and K were good, but less good for Al, Mg and Ca, especially after short reaction times. At 90 °C agreement for pH, SiO2 and Na was reasonable, but not as good for the other elements, and all modeling results for short reaction times did not match experimental results as well as the longer time results.This study demonstrates that reaction progress modeling provides a powerful tool for predicting hydrothermal rock-water interactions, with results expected to improve, as more and better quality thermodynamic and kinetic data become available and as process-oriented simulators incorporate better and more comprehensive sub-models for mineral dissolution and growth.

Hydrothermal Synthesis of Mordenite Type Zeolite

Zeolite is a crystalline alumino-silicate microporous material, which has been widely used as ion-exchangers, adsorbent and catalyst.
 Recently, several researches highlights the progress of zeolite-based catalysts in the CO2 conversion to valuable products.
 In the present work, hydrothermal synthesis of mordenite zeolite crystals, with composition of the chemical products Al2O3, 12.5 SiO2,2.4 NaOH, 110 H2O at 160°C for 96 hours (4 days) at Ph 11 is described. 
 Results of characterization of the mordenite zeolite by XRD, FTIR, EDAX, SEM, TGA, are presented and discussed.
 In the present work, hydrothermal synthesis and characterization of mordenite zeolite crystals is described.

Tuning High-Density Polyethylene Hydrocracking through Mordenite Zeolite Crystal Engineering

We investigate the hydrocracking of high-density polyethylene using a bifunctional Pt/Al2O3 and modified mordenite acid catalyst. Mass transport limitations impact polymer diffusion into the mordenite pore complex. Initial reaction intermediates are formed on the zeolite’s outer surface. Intercrystallite open-end mesopores improve the diffusion of reaction intermediates deeper into the crystal. Recrystallization and desilication of mordenite lead to a higher polymer conversion and shift the product distribution maximum from pentanes to hexanes and heptanes. The nature of mesopores (occluded or open) and total Brønsted acidity significantly impact zeolite activity and selectivity.

Highly dispersed Cu-anchored nanoparticles based mordenite zeolite catalyst (Cu-MOR): Influence of the different preparation methods for direct methane oxidation (DMTM) to methanol

Methane is widely recognized as one of the most significant greenhouse gases released into the atmosphere by shale gas and natural gas, contributing to global warming. Developing innovative technology for converting methane into transferable, storable, and useable liquid fuels is essential for long-term sustainability and carbon neutrality. Direct methane oxidation (DMTM) is one of the most efficient and cost-effective methods for producing methanol. The purpose of this research was to develop a highly active Cu-loaded mordenite zeolites (Cu-MOR) catalyst by the hydrothermal and ion exchange processes. Different methods were employed for Cu incorporation via double solvent, physical mixing, wetness impregnation, and incipient wetness impregnation. The synthesized catalysts were characterized by X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), N2-adsorption analysis, Fourier Transform Infrared Spectroscopy (FTIR), and Methane Temperature Programmed Desorption (CH4-TPD). The DMTM was performed, and it was found that the Cu-MOR (WI) catalyst that was prepared by wetness impregnation exhibited a higher methanol yield (26.5 μmol gcat−1) compared to other catalysts as a result of the high metal dispersion and high methane adsorption. According to data from TEM and CH4-TPD, this superior performance was strongly related to the particle sizes of copper and the synthesis methods used. Additionally, it was discovered that the longer the methane was in contact with the Cu-MOR (WI), the greater the amount of methanol that was produced (83.3 μmol gcat−1). Based on the finding that the Cu-MOR (WI) catalyst is highly efficient for the DMTM, this study has the potential to significantly decrease methane emissions.

Pyrolysis of Palm Fronds Waste into Bio-Oil and Upgrading Process Via Esterification-Hydrodeoxygenation Using Cu–Zn Metal Oxide Catalyst Loaded on Mordenite Zeolite

Pyrolysis of Palm Fronds Waste into Bio-Oil and Upgrading Process Via Esterification-Hydrodeoxygenation Using Cu–Zn Metal Oxide Catalyst Loaded on Mordenite Zeolite

Organic Structure-Directing Agent Free Synthesis of Mordenite with Seeds, Used as A Support for Mo Catalysts in the Transesterification of Soybean Oil

This work prepared mordenite using seeds and without organic structure-directing agents (OSDAs). The Mo/Mordenite was prepared through wet impregnation and the catalysts’ performance was checked for transesterification of soybean oil with methanol. The mordenite zeolite was prepared through hydrothermal crystallization under static conditions with a molar composition of 6Na<sub>2</sub>O:Al<sub>2</sub>O<sub>3</sub>:30SiO<sub>2</sub>:780H<sub>2</sub>O. The catalyst samples were characterized crystallinity through X-ray diffraction, elemental composition by X-ray fluorescence spectroscopy, Surface areas by N<sub>2</sub> adsorption-desorption, surface morphology scanning electron microscopy, functional group by infrared spectroscopy and active sites by temperature programmed desorption of ammonia. The transesterification of soybean oil was carried out using the following parameters: 5% catalyst by weight, 1:12 oil to methanol molar ratio, at 200°C for either 12 h or 24 h. X-ray diffraction patterns showed the characteristic peaks of the mordenite structure. After molybdenum oxide was added, the structure of mordenite zeolite was conserved while the specific surface area was reduced. The morphology can be described as a highly crystalline material with well-defined crystalline particles having a spherical profile characteristic of the typical morphology of sodium mordenite zeolite with a low silicon/aluminum ratio. The catalyst samples exhibited sites of a weak and medium-strength nature. The higher activity of the catalyst (Mo/Mordenite) about mordenite zeolite, could be justified by the existence of molybdenum. The wet impregnation of metal (Mo) on the surface of the MOR zeolite is an effective option to increase the acidity of the solid catalysts. Mordenite with 8.84% Mo could be a promising catalyst for the biodiesel factory.

Liquid-phase benzylation of toluene by benzyl alcohol over micro-mesoporous hierarchical mordenite zeolite.

In this work, post-synthetic effective acid (HNO3) and base (NaOH) etching technique are used to create hierarchical mordenite having different pore structure. The powder X-ray diffraction (P-XRD) technique was used to confirm the crystalline structure of the base-modified and acid-modified mordenite. Field emission-scanning electron microscope (FE-SEM) was employed to confirm the structural morphology of the materials. The modified mordenite was further characterised by inductive coupled plasma-optical emission spectrometry (ICP-OES), N2 adsorption-desorption isotherms, thermogravimetric analysis (TGA), and acid-base titration, to confirm the structural integrity, presence of active acidic sites, and other vital parameters. The structure was well conserved after the change, as evidenced by the characterisation. The toluene benzylation with benzyl alcohol using hierarchical mordenite and H-mordenite produced mono-benzylated toluene. Comparison between acid treated, base treated, and H-mordenite was done. All samples were catalytically active as proved by the catalytic result in the benzylation reaction. The results show that the base alteration dramatically enhances the mesoporous surface area of H-mordenite. Furthermore, the acid-treated mordenite had the highest benzyl alcohol conversion (75%), but the base-modified mordenite had benzyl alcohol conversion of 73% with the highest mono-benzylated toluene selectivity (61%). The process was further optimised by varying the reaction temperature, duration, and catalyst quantity. Gas chromatography (GC) was used to evaluate the reaction products and gas chromatography-mass spectrometry (GC-MS) was used to confirm them. Introduction of mesoporosity in the microporous mordenite was found to have significant effect on their catalytic activity.

CO methanation over highly active and coke-resistant ruthenium-doped fibrous mordenite zeolite catalyst for synthetic natural gas (SNG) production

Synthetic natural gas, or SNG, can be used as a low-carbon substitute for fossil fuels such as coal, gasoline, and natural gas. SNG can be produced by methanation of CO using an appropriate and efficient catalyst. In this study, a ruthenium-doped fibrous silica-mordenite (Ru-FSMOR) catalyst was prepared by a microemulsion method for CO methanation. X-ray diffraction (XRD), transmission electron microscopy (TEM), N2 adsorption-desorption, Fourier transform infrared (FTIR)-KBr, FTIR-pyrrole adsorption, hydrogen temperature-programmed reduction (H2-TPR), and thermogravimetric analysis (TGA) were used to examine the catalytic properties. The Ru-FSMOR catalyst demonstrated substantially improved catalytic capacity at 450 °C, with 84% conversion of CO and 78% CH4 yield compared to other catalysts. In addition, the Ru-FSMOR demonstrated excellent thermal stability, as evidenced by the absence of any deactivation after 100 h. Multiple factors, including high surface area, basicity, and the presence of uniformly distributed Ru, which served as CO and H2 adsorption sites, significantly improve the CO methanation activity. The Ru-FSMOR exhibited optimum metal-support interaction amongst the series of catalysts evaluated, inhibiting crystallite movement and protecting against coke deposits. Additionally, in-situ FTIR spectroscopy revealed that CO and H2 molecules are activated by linear adsorption of CO* as intermediates. These disintegrate into immobilized C*, which undergoes hydrogenation during CO methanation to produce methane.