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Cyclohexylphenol (CHP) is a high added-value chemical, extensively used for the preparation of dyes, resins and biocides. This molecule is currently synthetized by phenol alkylation with cyclohexene/cyclohexanol using highly polluting mineral Bronsted acids as catalysts. The present contribution reports the one-pot production of cyclohexylphenol via hydroalkylation, using phenol as the only organic reactant, over a number of bifunctional catalysts consisting of Co2P (5 wt.% Co) supported over different zeolites (ferrierite, mordenite, beta and MCM-22). Phenol conversion increased in the order: Co2P/Mordenite (30%)

In this study, one-pot syntheses of cancrinite (CAN) and analcime (ANA) frameworks from mordenite (MOR) natural zeolite were performed for the first time. The effects of the synthesis gel composition and alkalinity on the phase formation and crystallinity of the product were investigated. All studied zeolites were evaluated for their catalytic activities in ethanol conversion reactions from 473 K to 673 K and at 1 atm. The results suggested that the formation pathways of CAN and ANA are highly dependent on the alkalinity of the synthesis solution and the type of starting material regardless of synthesis template. The use of natural MOR zeolite (MORNZ) in the synthesis can contribute to highly crystalline ANA structures comparable to the ANA products obtained from fumed silica and sodium aluminate (NaAlO2). The quantity and locations of the acidic-cationic dual active sites of the proton-form product zeolites are suitable for synthesizing acetaldehyde from ethanol with over 90% product selectivity. However, further development of synthesis procedures to enhance the surface area is needed to improve the ethanol conversion of the resulting zeolites. This work provides a new perspective on highly crystalline and pure-phase zeolitic structural formations from natural zeolite and their potential application in ethanol conversion.

Methane over-oxidation by copper-exchanged zeolites prevents realization of high-yield catalytic conversion. However, there has been little description of the mechanism for methane over-oxidation at the copper active sites of these zeolites. Using density functional theory (DFT) computations, we reported that tricopper [Cu3 O3 ]2+ active sites can over-oxidize methane. However, the role of [Cu3 O3 ]2+ sites in methane-to-methanol conversion remains under debate. Here, we examine methane over-oxidation by dicopper [Cu2 O]2+ and [Cu2 O2 ]2+ sites using DFT in zeolite mordenite (MOR). For [Cu2 O2 ]2+ , we considered the μ-(η2 :η2 ) peroxo-, and bis(μ-oxo) motifs. These sites were considered in the eight-membered (8MR) ring of MOR. μ-(η2 :η2 ) peroxo sites are unstable relative to the bis(μ-oxo) motif with a small interconversion barrier. Unlike [Cu2 O]2+ which is active for methane C-H activation, [Cu2 O2 ]2+ has a very large methane C-H activation barrier in the 8MR. Stabilization of methanol and methyl at unreacted dicopper sites however leads to over-oxidation via sequential hydrogen atom abstraction steps. For methanol, these are initiated by abstraction of the CH3 group, followed by OH and can proceed near 200 °C. Thus, for [Cu2 O]2+ and [Cu2 O2 ]2+ species, over-oxidation is an inter-site process. We discuss the implications of these findings for methanol selectivity, especially in comparison to the intra-site process for [Cu3 O3 ]2+ sites and the role of Bronsted acid sites.

The selective catalytic oxidation of ammonia (NH3-SCO) to N2 and H2O at low temperatures was studied to remove low-concentration (50 ppm) NH3 from the air. A series of mordenite (M20)-supported Pt-Au alloy catalysts with different Pt:Au ratios were synthesized and tested in the NH3-SCO. The NH3 conversion and N2 selectivity both depended on the ratio of Pt to Au. The 0.52 wt% Pt84Au16/M20 catalyst showed the highest NH3 conversion (90% at 144 °C) even better than Pt100/M20, which was ascribed to the combination of electron-deficient Pt and electron-rich Au in the alloy nanoparticles. The effects of acid sites on the NH3-SCO were investigated by NaOH treatment of Pt84Au16/M20 catalyst. Results suggested that the acid sites could help to increase NH3 conversion, and that Bronsted acid sites are essential for the selective formation of N2.

A series of mono (Ni, Cu, Co), bi (NiCu, NiCo, CuCo), and trimetallic (NiCuCo) mordenite supported catalysts were characterized and evaluated for the continuous, near-atmospheric pressure, thermal deoxygenation of acetic acid. Acetic acid was selected as a model reactant due to its abundance in both biomass pyrolysis upgrading streams and its analogous structure to carboxylic acids found in vegetable oil upgrading streams. Surface area and metal loading were nearly constant for all studied catalysts, allowing an in-depth direct comparison of the metallic activity for reaction pathways including gasification, decarboxylation, decarbonylation, hydrodeoxygenation, and ketonization. In the absence of Ni or in the absence of H 2, the observed catalytic activity was low. Results from the bimetallic samples at 400 °C highlighted the importance of Ni for H2 activation and Co for the simultaneous promotion of hydrodeoxygenation and gasification. A nearly linear correlation between the Ni content and the conversion of acetic acid was observed at 400 °C. Cryogenic argon isotherms revealed the location of metal sites within the mordenite pore, further emphasizing the impact of confining environments on the deoxygenation of bio-derived compounds. TGA, TPR, and TPD studies provided information on catalyst stability, reducibility, and acidity, respectively. HRTEM indicated that agglomerates formed under the studied reaction conditions. The fresh Ni/MOR catalyst, under differential conversion conditions, was stable for ~ 24 h at 460 °C, for an additional ~ 20 h upon regeneration at 460 °C, and for an additional 30 h upon regeneration at 500 °C. Long-exposure activity was observed in the Ni/MOR catalyst, favoring hydrodeoxygenation and decarbonylation for at least 70 h under integral conversion conditions. In the bimetallic NiCo/MOR catalyst, Co stabilized Ni active sites in a co-located configuration which promoted hydrodeoxygenation, but also promoted gasification, and eventually lead to coking/lower conversion.

A biased acid site distribution in mordenite (MOR), which refers to the enrichment of acid sites within 8-membered ring (MR) channels, was observed with the addition of N-methyl-2-pyrrolidone (NMP)...

Cuban and Mexican zeolites are of particular interest from economic outlook because of their exceptional properties and abundance. Here, we present the results of the comparative study of the elemental, structural, morphological, thermal and textural properties of natural zeolites: clinoptilolite, mordenite and erionite from various deposits. Despite a complex phase and element compositions of the studied materials, some general features were detected. The observed dehydration steps are related to water desorption from porosity of different size ranges: mesopores, main and small zeolite voids. This dehydration pattern interferes with the exchangeable cation composition that also affects the general trends. Thermochemical properties of samples are influenced by the geographical location of the deposits. Depending on the origin of the sample, the dehydration enthalpy varies in quite a wide range, which is a function of both zeolite framework structure and exchangeable cation composition. The study of meso- and macropore systems reveals that all the samples exhibit multimodal pore size distribution and possess significant amounts of mesoporosity and even macroporosity. Among the studied samples, the mordenite from Palmarito de Cauto, the clinoptilolite from Etla and the erionite from Agua Prieta (Sonora) have a significant number of pores with average size of about 3 nm. All the samples, except erionite from Agua Prieta, show macroporosity with rather well-defined pore size between 0.3 and 2 μm. The porosity over mass does not change noticeably from one sample to other and varies from 0.32 to 0.65 cm3 g−1.

Channeling carbon dioxide The separation of gas molecules with physisorbents can be challenging because there is often a tradeoff between capacity and selectivity. Zhou et al. report a template-free hydrothermal synthesis of the one-dimensional channel zeolite mordenite, in which some silicon was replaced by iron. Rather than forming a powder that requires further shaping, this mechanically stable material self-assembled into monoliths. Iron atoms bound in tetrahedral zeolite sites narrowed the channels and enabled the size-exclusion separation of carbon dioxide (CO 2 ) over nitrogen (N 2 ) and methane. High CO 2 uptake and highly efficient CO 2 –N 2 separation was demonstrated for both dry and humid conditions. Science , aax5776, this issue p. 315

JACS Au 1(9), 1412 – 1421 (2021). doi:10.1021/jacsau.1c00196, Cu-zeolites are able to directly convert methane to methanol via a three-step process using O$_2$ as oxidant. Among the different zeolite topologies, Cu-exchanged mordenite (MOR) shows the highest methanol yields, attributed to a preferential formation of active Cu–oxo species in its 8-MR pores. The presence of extra-framework or partially detached Al species entrained in the micropores of MOR leads to the formation of nearly homotopic redox active Cu–Al–oxo nanoclusters with the ability to activate CH$_4$. Studies of the activity of these sites together with characterization by $^{27}$Al NMR and IR spectroscopy leads to the conclusion that the active species are located in the 8-MR side pockets of MOR, and it consists of two Cu ions and one Al linked by O. This Cu–Al–oxo cluster shows an activity per Cu in methane oxidation significantly higher than of any previously reported active Cu–oxo species. In order to determine unambiguously the structure of the active Cu–Al–oxo cluster, we combine experimental XANES of Cu K- and L-edges, Cu K-edge HERFD-XANES, and Cu K-edge EXAFS with TDDFT and AIMD-assisted simulations. Our results provide evidence of a [Cu$_2$AlO$_2$]$^{2+}$ cluster exchanged on MOR Al pairs that is able to oxidize up to two methane molecules per cluster at ambient pressure., Published by ACS Publications, Washington, DC

Conventional washing methods release little radioactive cesium fixed in soils. Adding a Cs+ adsorbent to a suspension of Cs-contaminated soil rapidly removes the Cs+ released to the solution, causing more Cs+ release from the soil. We investigated this method by adding a sheet embedded with mordenite powder to a suspension of 133Cs+-retaining wet/dry montmorillonite and water/0.1 mol L−1 KNO3. Adding the sheet increased Cs+ release in all cases, with the highest increase for wet montmorillonite in water. The advantages of this method are the easy removal of the sheet from the suspension and the low Cs concentration in the final solution.

Selective and stable production of C2 oxygenates from syngas is enabled by a phosphate-passivated mordenite catalyst used in tandem with a commercial Cu/ZnO/AlMgOx catalyst. Unmodified mordenite used in this arrangement is accompanied by substantial hydrocarbon formation and carbon deposition. Therefore, phosphate groups are used to remove or significantly reduce Bronsted acidity in mordenite by capping aluminum sites. Such groups are stable to calcination and catalyst regeneration. Trimethylphosphite is used as a phosphate precursor because it is able to enter the 12 membered-ring pores of mordenite where hydrocarbon formation occurs, but not enter the 8 membered-ring side-pockets, where methanol carbonylation occurs selectively. The catalyst was characterized using X-ray fluorescence, X-ray diffraction, and thermal gravimetric analysis. Optionally, a third bed of Cu/ZnO/AlMgO x catalyst is able to hydrodeoxygenate acetic acid to ethanol. The C2 oxygenate selectivity is over 96% and among the best reported in a single reactor with a syngas feed.

The growing consumption of light olefins has stimulated intensive researches on methanol to olefin (MTO) process which possesses great advantages for coal conversion to value-added chemicals in an environmentally benign way. The catalysts commonly used for MTO process faces several challenges such as poor selectivity control, low hydrothermal stability and short lifetime. In the present study, we prepared a series of mordenite zeolites with variable Al contents (Si/Al molar ratios of 51−436) by a sequential dealumination treatment of air-calcination and acid leaching. The textural properties, acidity and Al location before and after the dealumination treatment have been systematically studied and their effect on MTO especially the methanol to propylene (MTP) performance was thoroughly investigated. The mordenite zeolites with the Si/Al ratios over 150 selectively catalyzed methanol conversion in the MTP pathway, providing a high propylene selectivity of 63% and propylene/ethylene ratio of > 10. Compared to the low-silica MOR catalysts, highly dealuminated MOR showed much higher stability and longer lifetime, which can be further enhanced via harsh hydrothermal pretreatment. Furthermore, the lifetime was highly related to the crystal size along c-axis. The excellent performance of highly dealuminated MOR is likely ascribed to the mesopores formed upon dealumination and the scarce Al sites located in the T sites shared by the 8-member ring (MR) side pockets and 12-MR pore channels.

Mordenite zeolite is now the most promising catalyst for the carbonylation of dimethyl ether (DME) to methyl acetate because of the excellent initial activity and selectivity, but it suffers from r...

Copper-exchanged zeolites are promising catalysts for the direct methane-to-methanol reaction, but the design of improved catalysts has been hampered by limited understanding of the active site str...

There is significant interest in improving methanol yields from methane in copper-exchanged zeolites. Interestingly, zeolites with proton, H+, precursors provide greater methanol yields and selecti...

A zeolite membrane reactor can be employed for hydrogenation of CO2 to methanol. The removal of water from the reaction environment would increase the reaction rate and the achievable conversion. The separation of water from mixtures containing CO2, hydrogen and water at suitable temperatures for this reaction was tested with several zeolite membranes (zeolite A, mordenite, zeolite T, chabazite and Ti-Chabazite). Zeolite A provided the best H2O/H2 separation factor. Preliminary experiments comparing a traditional reactor and the combination of a traditional reactor with a membrane reactor show that the yield of methanol was improved, in one case being higher than the limit corresponding to the thermodynamic equilibrium in a conventional reactor.

Mordenite (MOR)-type zeolites with a Si/Al molar ratio of up to 13 with crystallite sizes of ca. 60 nm were successfully synthesized from Al-rich aluminosilicates with a Si/Al ratio of 2 and additional SiO2 under seed-assisted hydrothermal conditions for 6 h or longer without any organic structure-directing agents (OSDAs). In stark contrast, under the same hydrothermal conditions for 6 h, control experiments using starting reagent(s), such as Al-poor aluminosilicate, pure SiO2, tetraethyl orthosilicate, and Al(NO3)3, all of which are typically employed for zeolite synthesis, failed to yield MOR-type zeolites. The penta-coordinated Al species, which are present in Al-rich aluminosilicates and are more reactive than the tetra- and hexa-coordinated Al species typically found in alumina and Al-poor aluminosilicates, played a decisive role in the OSDA-free synthesis of MOR-type zeolites.

Bifunctional catalysts on the basis of Ukrainian natural mordenite-clinoptilolite rocks modified by hydrochloric acid and by witness impregnation with nickel have been synthesized. Samples have been characterized by means of XRD, XRF, FTIR-spectroscopy, low temperature nitrogen adsorption/desorption, DTA/TG, TEM. Catalysts have been tested in micro pulse linear hexane isomerization. Hydrochloric acid treatment of natural zeolite rock leads to silica-to-alumina ratio increasing and raising the BET surface as well as the volumes of mesopores and micropores. The nickel nanoparticles deposited over zeolite crystals have a predominant size of 10 nm, but for some samples smaller ones of 5 nm and bigger ones of 20–50 nm have been found using TEM investigations. Pyridine sorption shows Bronsted and Lewis acidity of the catalysts, moreover the lower hydrochloric acid concentration using leads to practically equal Bronsted and Lewis acidity, the higher acid concentrations causes the Lewis acidity predominance. DTA/TG investigations show that water physically sorbed in the pores of the samples has been removed up to 200 °C from lager cavities of acid-treated catalysts and up to 500 °C from narrower cavities for untreated initial rock. Removing zeolite structure water up to 800 °C causes the dehydroxylation and Bronsted acidity transformation into Lewis acidity. The sample dealuminated by 1 mol dm−3 acid with nickel nanoparticles of 5–8 nm demonstrates the best performance in the isomerization of n-hexane. It is characterized by a 20% yield of hexane isomers at 250 °C and 70% selectivity.

The effects of the ultrasonic (US) pretreatment of synthesis gel for the preparation of mordenite zeolite were studied in comparison with the classical stirring method. Even though the US pretreatment was performed before the hydrothermal crystallization, it significantly affected the properties of the obtained mordenite crystals. The US-assisted procedure resulted in a material with improved textural characteristics, in particular, the micropore volume accessible for nitrogen molecules in the as-made form. On the other hand, mordenite prepared with the classical stirring method demonstrated comparable sorption properties only after a postsynthetic treatment. Moreover, in the case of US-pretreated mordenite, altered crystal shape and more homogeneous morphology were observed. 29Si magic-angle spinning nuclear magnetic resonance (MAS NMR) demonstrated that the US pretreatment introduced structural changes on the atomic level, resulting in fewer defects (reflected in the number of silanol groups) and less pore blockage (affected by Na+ cations) for the as-made sample.

The research about modification of mordenite characteristics has been performed by H2C2O4 and/or NaOH treatments and catalytic activity tests in hydrotreating of pyrolyzed a-cellulose. Commercial mordenite (HSZ-604OA) as mordenite control (HM) immersed in 0.05, 0.5, and 1.0 M H2C2O4 at 70 °C for three hours resulting in HM-0.05, HM-0.5, and HM-1. The four mordenites were immersed in 0.1 M NaOH for 15 minutes resulting in BHM, BHM-0.05, BHM-0.5, and BHM-1. The catalysts obtained were analyzed by XRD, SAA, ICP, and acidity test. The catalytic activity of the mordenites was evaluated in hydrotreating of pyrolyzed a-cellulose using stainless steel reactor with an H2 gas flow rate of 20 mL.min−1 at 450 °C for two hours with a catalyst: feed weight ratio of 1:60. The liquid products obtained from the hydrotreating were analyzed using GC-MS. The research results showed that the H2C2O4 and/or NaOH treatment towards the mordenites increased Si/Al ratio and decreased crystallinity. The acidity of mordenites decreased along with the increase of the Si/Al ratio. The average pore diameter of BHM, BHM-0.05, BHM-0.5, and BHM-1 mordenites were 2.898; 3.005; 3.792; 7.429 nm, respectively. The BHM-0.5 mordenite showed the highest catalytic activity in generating liquid product (88.88 wt%) and selectivity toward propanol (4.87 wt%). The BHM-1 mordenite showed catalytic activity in generating liquid product (41.16 wt%) and selectivity toward ethanol (1.21 wt%) and 2-heptyne (4.36 wt%). Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

One-step methane-to-methanol conversion is a “dream reaction” for chemists. In this Letter, continuous direct conversion of methane into methanol with steam under mild conditions using Cu(II)-excha...

Recently, there is sustainable growth in the biodiesel industry due to high utilization of fossil fuels all over the world. Therefore, biodiesel production is increasing very high which shows the production of the by-product glycerol is also increasing which has huge applications of producing value-added products like solketal, lactic acid, dihydroxy acetone, glyceraldehydes. Among them, solketal has a key important to improve properties of gasoline by increasing the octane number. In this work, conversion of glycerol to solketal is carried out by using heterogeneous catalysts like zeolite beta, mordenite, ZSM-5, SAPO-34, SAPO-11, and Y-zeolite. The reaction was done in a batch reactor at 60 °C with a time of 180 min. Highest conversion was observed over zeolite mordenite catalyst due to highest Bronsted acidity among them.

The direct transformation of ethanol to acetaldehyde is an important step in the cascade conversion of bioethanol to higher value chemicals and for the development of sustainable fuels. Herein, zinc oxide supported on alkali cation-exchanged mordenite (ZnO/M–MOR) prepared by a simple wetness impregnation method, is shown to be a selective and stable catalyst for the direct dehydrogenation of ethanol to acetaldehyde at 400 °C under continuous flow conditions. Through variation of the ZnO loading and the zeolite counter-cation (Na, K, Rb, Cs), an optimum catalyst material was identified, ZnO/Rb–MOR loaded at 3.5 wt% Zn. Acetaldehyde productivity (normalised to Zn) could be increased by over 80% and ethylene selectivity reduced to 0.9 % through simple variation of the extra-framework alkali cation. Very low ethylene production leads to low levels of carbonaceous deposits and therefore minimal deactivation at short time on stream (< 5 h). Detailed analysis of the optimized system reveals excellent selectivity and stability beyond 120 h time on stream, resulting in an average acetaldehyde productivity of 16 mmol gcat−1 h−1 and overall acetaldehyde selectivity of 90% whilst operating at an ethanol conversion level of 40 %. Additionally, the use of a zeolite support is shown to greatly improving the usage efficiency of Zn atoms by virtue of an acetaldehyde productivity increase from 20 to 48 mmol mmolZn−1 h−1 for unsupported and supported ZnO, respectively. The new catalyst system shows that ZnO can be tuned to give very low ethylene selectivity and extended lifetimes in ethanol dehydrogenation to acetaldehyde which has not previously been reported.

Expectations for industrial implementation of direct conversion of CH4 to CH3OH are growing with the increasing demand for energy-efficient chemical processes. In this study, catalytic production of CH3OH by direct oxidation of CH4 with O2 was performed using Cu zeolite catalysts in a CH4/O2/H2O flow reaction. Among the various Cu zeolites investigated, the Cu-MOR catalyst exhibited relatively high CH3OH production with a turnover number of 7.4 molCH3OH molCu−1 over 24 h (CH4 conversion: 0.011%). The catalytically active Cu species and catalytic cycle were investigated by in situ simultaneous X-ray absorption and infrared spectroscopy. The results suggest that the key to the catalytic cycle over Cu-MOR is the redox of Cu(I)/Cu(II) species. Furthermore, H2O-adsorption-included dynamic Cu species are revealed to be catalytically active.

Among the many industrially important zeolites, mordenite is found to be interesting because of its unique and exceptional physical and chemical properties. Mordenite (high silica zeolite) is generally prepared by the hydrothermal method using TEA+ cations. TEA+ cations are the best templating agent, though they can create a number of issues, for instance, generating poison and high manufacturing cost, wastewater contamination, and environmental pollution. Hence, it is necessary to find a mordenite synthesis method without using an organic template or low-cost template. In this review, a number of unique sources were used in the preparation of mordenite zeolite, for instance, silica sources (rice husk ash, silica gel, silica fumes), alumina sources (metakaolin, faujasite zeolite) and sources containing both silica and alumina (waste coal fly ash). These synthesis approaches are also based on the absence of a template or low-cost mixed organic templates (for instance, glycerol (GL), ethylene glycol (EG), and polyethylene glycol 200 (PEG)) or pyrrolidine-based mesoporogen (N-cetyl-N-methylpyrrolidinium) modifying the mordenite framework which can create unique properties. The framework properties and optical properties (indium-exchanged mordenite zeolite) have been discussed. Mordenite is generally used in alkylation, dewaxing, reforming, hydrocracking, catalysis, separation, and purification reactions because of its large pore size, strong acidity, and high thermal and chemical stability, although the applications are not limited for mordenite zeolite. Recently, several applications such as electrochemical detection, isomerization, carbonylation, hydrodeoxygenation, adsorption, biomass conversion, biological applications (antibacterial activity), photocatalysis, fuel cells and polymerization reactions using mordenite zeolite were explored which have been described in detail in this review.

Zr-modified bicontinuous lamellar silica mordenite supported Pt catalysts were synthesized using the zirconyl chloride oxahydrate as the precursor for Zr species by the incipient wetness impregnation method. The influence of zirconium loading on the properties of Zr-modified HM@KCC-1 catalysts for n-hexane isomerization were studied. The results of XRD and lattice structure from IR study indicated that increasing zirconium loading did not change the properties of catalysts. The IR study with pre-adsorbed 2,6-dimethylpyridine as a probe molecule affirmed that increasing zirconium loading could increase the Lewis acid sites. The generation of protonic acid sites which were active in n-hexane hydroisomerization was mainly from molecular hydrogen through a hydrogen spill-over mechanism as established by in situ-IR study. The results for the catalytic testing indicated that PtZr/HM@KCC-1 catalyst was highly selective in n-hexane hydroisomerization due to abundant permanent Lewis acid sites for its promotive effect in the generation of protonic acid sites. However, the incorporation of excessive zirconium amount up to 10 wt percent loading led to a decline in the amount of protonic acid sites generated, thus reduced the hydroisomerization performance in the process. The optimum conditions for hydroisomerization of n-hexane over Pt5Zr/HM@KCC-1 were reaction temperature of 293 °C, treatment temperature of 474 °C and F/W of 502 mL/g.min with the predicted value for isomer yield of 83.9%.

Three Ni catalyst supported on mordenite zeolite with the same content of nickel, ∼2 wt.%, were prepared by incipient wetness impregnation (IWI), ionic exchange (IE), and deposition-precipitation (DP) methods. The catalysts were characterized by, X-ray diffraction (XRD), textural properties, temperature-programmed reduction (TPR), transmission electron microscopy (TEM) and scanning electron microscopy / energy-dispersive spectroscopy (SEM/EDS). For all the catalysts conversion and selectivity were studied in naphthalene hydrogenation without or with thiophene in the feedstock. Despite the low nickel content, the three preparations showed a high initial total naphthalene conversion up to 94%. The Ni-IWI catalyst exhibited high selectivity to tetralin and deactivated very fast. Ni-IE catalyst had good activity; however, it shows deactivation and the main products are related to acid reactions. The Ni-DP shows high hydrogenation activity and was the most active catalyst, it generated decalins, especially cis-decalin and at a long reaction time on stream, the catalyst remains active. TEM and TPR results suggest that this behavior is related to the crystal sizes which in turn is conected with the preparation method. In presence of thiophene, all the catalysts deactivate; but the Ni-DP deactivation was slower.

Zeolites Y, A and mordenite (ZY, ZA and ZM) were obtained from diatomite in a template-free system, and the products were modified by thiourea (TU). Characterization studies results indicated that the TU molecules were loaded onto the exterior surfaces of the synthetic zeolites as well as the channels. Elemental analysis and energy-dispersive X-ray spectrometer proved that the TU molecules loaded on to ZA were more than ZY and ZM. Removal of Cd(II) was investigated, and it was found that the modified zeolites have higher removal capacity, modified ZA is especially noticeable. In the adsorption experiments, the effects of various parameters such as sorbent content, contact time, concentration of cadmium solution, pH, selectivity and regeneration were discussed. At the best removal efficiency by modified zeolites, the maximum adsorption capacity is 94.3 mg·g−1, 103.2 mg·g−1 and 89.7 mg·g−1 at 25 °C, respectively. The sorbents show good efficiency for the removal of Cd(II) in the presence of different multivalent cations and have good regeneration effect. For the modified samples, removal experiments take place via ion exchange and complexation processes.

Present paper highlights the adsorption performances of mordenite (MOR), polyaniline-mordenite (PANI/MOR), copper oxide-mordenite (CuO/MOR) and silver oxide-mordenite (AgO/MOR) nanocomposites towar...

Nylon 6-mordenite composite membranes having porous morphology were applied to the selective separation of heavy metal ions from aqueous heavy metal solution with Pb2+, Cu2+ and Cd2+. The membrane preparation was carried out in the wet phase inversion method using methanol/CaCl2/Nylon 6 solution. The resultant membranes containing mordenite powders with 10, 20 and 30 wt% loading were obtained as coagulated in water. Depending on the mordenite loading in the composite membranes, the porous morphology was changed in a finger-like and/ or sponge structure. In batch adsorption experiments, the higher mordenite loading in the composite membranes was the higher separation capacity for heavy metal ions. The composite membrane loading 30 wt% mordenite (NZC 30) had the optimal performance of Pb2+ ion capture in the maximum adsorption capacity of 38.5 mg/g at pH 5. The batch separation factor calculated using Langmuir isotherm parameters supported the selective adsorption of Pb2+ relative to those of Cd2+ and Cu2+. In addition, the permeabilities of water and the mixed ion solution with 20 mg/L concentration were investigated. The value of the separation factor of NZC 30 was 9.2 for Pb2+ against Cu2+. In the regeneration of the reused membranes, the values of the regeneration efficiency of NZC 30 still maintained a good separation performance in Pb2+ with 24.1 mg/g at 5-time reusing. Porous nylon 6-mordenite composite membranes were fabricated from methanol/CaCl2/Nylon 6 solution via the wet phase inversion method and applied to selective separation of Pb2+, Cu2+ and Cd2+ from mixture solution

Zr-mordenite catalysts were prepared by post-treatment method and H-mordenite catalyst was synthesized by hydrothermal method for the dimethyl ether carbonylation reaction. XRD, N2 adsorption/desorption, ICP-OES, SEM, TEM, UV–Vis, XPS, Raman, CO-TPD, NH3-TPD, 27Al MAS NMR, FTIR and Py-IR were employed to characterize the catalysts. The results demonstrated that part of Zr atoms existed in a tetrahedral coordination state after incorporating into the mordenite framework. Zirconium Lewis acid sites with the ability to absorb CO molecules were formed during this process although the amount of Bronsted acid sites in 8-member ring channels decreased upon the incorporation of zirconium. During the concentration of zirconium nitrate solution increased from 0.02 to 0.08 mol/L, the Zr-mordenite catalyst through post-treatment with 0.04 mol/L zirconium nitrate solution exhibited the best catalytic performance at 473 K and 1 MPa. Dimethyl ether conversion and methyl acetate selectivity increased to 78% and 96% respectively compared with H-mordenite catalyst. Schematic of Zr incorporating MOR framework

The hydrodeoxygenation (HDO) of 2-methoxy phenol (MP), a lignin-derived compound, has massive prospective for valuable compounds production. The lignin derived model compounds can be used for production of green chemicals. The model compound MP conversion into cyclohexane was investigated over Ru metal loaded on various supports (ZSM-5, Y-zeolite, β-zeolite, COK-12, mordenite, ZrO2, and TiO2). The catalytic properties such as the acidic sites, pore size, and morphology influenced the HDO activity and selectivity of the cyclohexane. The yield of cyclohexane increases up to optimum acidity further increases the acidity of the catalyst, the product yield decreased. The experiments carried out at temperature range of 200–300 °C, and 1–25 bar hydrogen pressure in a fixed bed reactor. The parameters greatly influenced the HDO as well as the cyclohexane yield, selectivity, and MP conversion. The highest conversion (100%) and yield of cyclohexane (99.0%) observed at 250 °C under pressure of 20 bar with Ru/ZSM-5 catalyst. Further the recyclability and stability have been checked and observed that Ru/ZSM-5 is stable up to 200 h and displayed excellence activity in both HDO and cyclohexane selectivity. Weight hourly space velocity (WHSV) was investigated (0.5–1.5 h−1). The suitable WHSV found for HDO of 2-methoxy phenol and cyclohexane yield was 1 h−1. The reaction mechanism showed that the Ru/ZSM-5 catalyst provoked the HDO compared to the others catalyst.

In this work, the selectivity of different solid catalysts in the alkylation reaction of toluene with hex-1-ene has been studied in order to maximize mono-alkylated products. The reaction has been carried out in a fixed-bed reactor, at 120°C. An industrial alkylation catalyst has been used as a reference along with three commercial acid zeolites with difference structures (faujasite, mordenite and beta). All of catalysts achieved total conversion. Mono-alkyltoluenes selectivity was higher than 95% in all cases and formation of di-alkyltoluenes was less than 4.5%. The main products, mono-alkyltoluenes, were identified by Nuclear Magnetic Resonance spectroscopy. This work analyses the effect of physicochemical and structural properties of solid catalysts on the selectivity to the different alkylation products.

A bicontinuous lamellar silica mordenite (HM@KCC-1) has been successfully synthesized by microemulsion technique assisted with mordenite-seed recrystallization, followed by protonation and impregnation with platinum (Pt). The catalysts were extensively characterized by XRD, N2 adsorption, FTIR, FESEM, TEM and ESR and the activity was tested in hydroisomerization of n-hexane. Fourier Transform-Infrared Spectroscopy (FT-IR) study through pyridine and 2,6- dimethylpyridine adsorption revealed that Pt/HM@KCC-1 possessed abundant Lewis acid sites and moderate Bronsted acid sites while Pt/HM possessed strong Lewis and Bronsted acid sites. At 300 °C, the conversion of n-hexane on Pt//HM@KCC-1 reached 75% with 98% isomer selectivity and 74% isomer yield. The enhancement of catalytic performance is attributed to the well-dispersed Pt nanoparticles, tuned acidic properties and improved textural properties which provided a well balance in the acid/metal functions. Thus, favours the reaction towards higher hydroisomerization selectivity, limiting the undesired consecutive cracking reaction.

Dimethyl ether (DME) carbonylation over mordenite (MOR) is a typical spatial confined reaction, but the superior shape selectivity is accompanied by a diffusion limitation of the microporous channel. Thus, enhancing mass transfer to improve the catalytic performance of MOR is important for its application. In this study, an unbiased chemical etching with a NH4F solution was employed to introduce secondary porosity into MOR. Through altering the etching temperature, a series of hierarchical MOR with different porosities were successfully prepared. XRD, Ar adsorption, and ICP together with the quantification of acid sites confirmed that the microporous structure and acidity of pristine zeolite were preserved after etching. The Weisz–Prater criterion was used to assess the internal diffusion limitation of DME and methyl acetate (MA). Moreover, toluene was chosen as a representative molecule in zero length column measurements, in order to explore the mass transfer of coke precursors in pristine and modified MOR. Combining the catalytic performance (i.e., TOFMA, selectivity, and deactivation rate constant) and diffusivity of molecules within MOR, we obtain insight into the influence of diffusion on zeolite-catalyzed DME carbonylation.

Low-temperature anaerobic methane conversion to methanol (MTM) using copper ion-exchanged mordenite (Cu-MOR) as the catalyst and water as the sole source of oxygen is promising for sustainable utilization of methane. Integrating in situ calorimetric, spectroscopic, and structural methodologies, we report a systematic study on energetics of water-cationic species-framework guest-host interactions as a function of water loading for several mordenites relevant to low-temperature MTM. Notably, the near-zero coverage hydration enthalpy on Cu-MOR is -133.1 ± 6.0 kJ/mol water, which is related to Cu-MOR regeneration using water as oxidant. The copper oxo sites are thermally stable up to 915 °C and remain chemically intact as an oxygen source after complete hydration and dehydration. This study underscores the importance of manipulating the oxidation state and coordination chemistry of transition metal guest species in zeolites by fine-tuning the partial pressure of water as a strategy for rational design, synthesis, and modification of catalysts.

Chemistry - a European journal 26(34), 7563 - 7567 (2020). doi:10.1002/chem.202000772, Copper‐oxo clusters exchanged in zeolite mordenite are active in the stoichiometric conversion of methane to methanol at low temperatures. Here, we show an unprecedented methanol yield per Cu of 0.6, with a 90–95 % selectivity, on a MOR solely containing [Cu$_3$($\mu$‐O)$_3$]$^{2+ }$active sites. DFT calculations, spectroscopic characterization and kinetic analysis show that increasing the chemical potential of methane enables the utilization of two μ‐oxo bridge oxygen out of the three available in the tricopper‐oxo cluster structure. Methanol and methoxy groups are stabilized in parallel, leading to methanol desorption in the presence of water., Published by Wiley-VCH, Weinheim

The hydrodeoxygenation (HDO) of m-Cresol (a representative of lignin bio-oil) has enormous potential for the production of valuable compounds. The products obtained from HDO of m-Cresol (m-Cr) are blendable into conventional fuels and essential for chemical industries such as plastic, fiber, rubber, resin, film, and coating industry. Ruthenium loaded acidic supports (ZSM-5, β-zeolite, y-zeolite, mordenite, COK12, ZrO2, TiO2) were used for the selective hydrodeoxygenation of m-Cresol into methylcyclohexane (MCXane). The effects of acid sites, as well as the pore size of the different supports on the hydrodeoxygenation activity and selectivity towards methylcyclohexane were addressed. The methylcyclohexane yield increased with increasing number of acid sites up to optimum acidity (532 μmol/gm) along with pore size (5.9 Ao). The experiments were carried out at 225–325 °C and 1–40 bar hydrogen pressure in a fixed bed reactor and observed that reaction temperature, and hydrogen pressure promoted the hydrodeoxygenation. The Ru/ZSM-5 is a stable (240 h) catalyst and displayed excellent behavior in both hydrodeoxygenation activity (100%) and methylcyclohexane selectivity (100%) for m-Cresol.

The adsorption selectivity, Sads, is a key metric that quantifies the efficacy of any adsorbent in mixture separations. It is common practice to use ideal adsorbed solution theory (IAST) for estimating the value of Sads, using unary isotherm data inputs. In a number of experimental investigations, the phenomena of selectivity reversals and adsorption azeotropy (Sads = 1) have been reported in the published literature; such reversals may result from changes in mixture compositions, pressures, or pore loadings. In many cases, IAST is unable to anticipate such selectivity reversals. In this article, configurational-bias Monte Carlo simulations are used to gain insights into the phenomena of selectivity reversals. Two fundamentally different scenarios of selectivity reversals have been identified. In the first scenario, selectivity reversals are caused by inhomogeneous distribution of adsorbates due to preferential location and siting of a guest species in the pore space. For example, CO2 locates preferentially in the side pockets of mordenite and in window regions of DDR, CHA, and LTA zeolites. CO2 also congregates around the extra-framework cations of NaX zeolite. IAST fails to anticipate such selectivity reversals because its development relies on the assumption that the competition between guest species is uniform within the pore space. In the second scenario, selectivity reversals are caused by entropy effects that manifest near pore saturation conditions; the component that is preferentially adsorbed is the one that has the higher packing efficiency. For a homologous series of compounds, the component with the smaller chain length is favored at high pore occupancies. For adsorption of mixtures of alkane isomers within the intersecting channel network of MFI zeolite, the linear isomer is favored on the basis of entropic considerations.

This study investigated the soil adsorption characteristics against gaseous mercury. A method for the adsorption tests using gaseous mercury was established, and the distribution coefficients for silica sand, decomposed granite soil, mordenite, and calcium bentonite were evaluated. Glass vials with polytetrafluoroethylene (PTFE) plugs were suitable for the adsorption tests as gaseous mercury did not adsorb onto the glass vials, indicating that the effects of the gaseous mercury adsorbed onto the glass vials are negligible. Although the PTFE plug could not completely seal a vial containing gaseous mercury, the leakage could be corrected using the damping time constant. The soil adsorption tests revealed changes in the gaseous mercury concentrations, which were fitted to the Langmuir nonequilibrium adsorption model. Assuming gaseous mercury did not leak from the vial, numerical simulations were conducted using the fitted parameters of the maximum adsorption amount, adsorption rate, and desorption rate. The evaluated distribution coefficients at equilibrium conditions were 56.3 mL/g for silica sand, 2070 mL/g for decomposed granite soil, 3490 mL/g for mordenite, and 7140 mL/g for calcium bentonite.

Acid treatment of mordenite was conducted using acetic acid to increase the Si/Al ratio. The acid treatment of mordenite by acetic acid was performed using sonication. The various time of treatments was used to investigate the effect of sonication in acid treatment of mordenite. Mordenite and all samples after treatment were characterized by ICP, FT-IR, XRD, and ammonia adsorption to measure their acidity. The Si/Al ratio of mordenite was increased from 11.33 to 17.31, 19.47, and 20.58 respectively for 3, 6, and 9 h of sonication. This result was supported by the T‒O bond vibration of samples which shift to higher wavenumber. The increase of the Si/Al ratio was followed by the decrease of acidity. The XRD test result revealed partial loss of mordenite framework after acid treatment. The results indicated that the sonication method can be used for acid treatment of mordenite.

Nylon 6–mordenite composite membranes were fabricated for adsorbing ethylene released from bananas. In the membrane fabrication, the wet–phase inversion method was employed when nylon 6/mordenite/m...

Precisely controlled crystal growth endows zeolites with special textural and catalytic properties. A nanosheet mordenite zeolite with a thickness of ca. 11 nm, named as MOR-NS, has been prepared using a well-designed gemini-type amphiphilic surfactant as bifunctional structure-directing agent (SDA). Its benzyl diquarternary ammonium cations structurally directed the formation of MOR topology, whereas the long and hydrophobic hexadecyl tailing group prevented the extensive crystal growth along b axis. This kind of orientated crystallization took place through the inorganic-organic interaction between silica species and SDA molecules present in the whole process. The thin MOR nanosheets, with highly exposed (010) planes and 8-membered ring (MR) windows, exhibited a much improved ethylene selectivity (42.1 %) for methanol-to-olefin (MTO) reactions when compared with conventional bulk MOR crystals (3.3 %).

Mordenite zeolite is considered a molecular sieve because of its adsorbent material characteristics used in the industry as a gas separator. High Si/Al ratios of this zeolitic material in its crystal lattice provide high thermal stability in the structure. To minimize the production costs, this work synthesized the mordenite zeolite in absence organic template (high costs of production). For this purpose, rice husk ash (silicon source) was used from a thermoelectric plant that uses biomass for power generation under the “Moving Grade Reactor” method and metakaolin (aluminium source) derived from the construction. To obtain the zeolitic material, an alkaline treatment with sodium hydroxide and deionized water was required. Different Si/Al ratios (5, 10, 15, and 20) were used to evaluate the highest efficiency in adsorption capacity. The textural properties of mordenite as a function of specific surface area ranged from 314 to 347 m2/g, with micropore volume 0.198–0.279 cm3/g with average pore diameter ranging from 5.9 to 6.2 A. N2 adsorption/desorption isotherms obtained for mordenite presented type IV hysteresis, characteristic of microporous materials. X-ray diffraction showed crystalline phases of mordenite zeolite, mostly. The FTIR reinforces the success of mordenite synthesis by the vibration bands corresponding to the zeolitic material. TGA revealed water desorption and absence of an organic director. The mean cation-exchange capacity values ranged from 1.10 to 1.78 meq/g indicating a 62% increase of 20-mordenite zeolite compared to 5-mordenite in the zeolitization process. This result is satisfactory and promising for the use of mordenite as adsorbent material.

Pyridine-modified mordenite (MOR) zeolite catalysts have attracted great attention in recent years due to their unique shape selectivity within eight-membered ring (8-MR) side pockets for dimethyl ...

Pyrolysis of Ulva prolifera macroalgae (UM), an aquatic biomass, was carried out in a fixed-bed reactor in the presence of three zeolites based catalysts (ZSM-5, Y-Zeolite and Mordenite) with the different catalyst to biomass ratio. A comparison between non-catalytic and catalytic behavior of ZSM-5, Y-Zeolite and Mordenite catalyst in the conversion of UM showed that is affected by properties of zeolites. Bio-oil yield was increased in the presence of Y-Zeolite while decreased with ZSM-5 and Mordenite catalyst. Maximum bio-oil yield for non-catalytic pyrolysis was (38.5 wt%) and with Y-Zeolite catalyst (41.3 wt%) was obtained at 400 °C respectively. All catalyst showed a higher gas yield. The higher gas yield might be attributed to that catalytic pyrolysis did the secondary cracking of pyrolytic volatiles and promoted the larger small molecules. The chemical components and functional groups present in the pyrolytic bio-oils are identified by GC–MS, FT-IR, 1H-NMR and elemental analysis techniques. Phenol observed very less percentage in the case of non-catalytic pyrolysis bio-oil (9.9%), whereas catalytic pyrolysis bio-oil showed a higher percentage (16.1%). The higher amount of oxygen present in raw biomass reduced significantly when used catalyst due to the oxygen reacts with carbon and produce (CO and CO2) and water.