Mesoporous ZSM-5 Zeolite Research Articles

Application of diffuse reflectance near-infrared spectrometry and chemometrics in characterization of micro and mesoporous ZSM-5 zeolites.

Evaluation of porosity type of zeolites is one of the critical topics in catalysis science. The relationship between external surface area and diffuse reflectance (DR) spectra in the near-infrared spectral region has been employed to propose a method for estimation of micro or mesoporosity in ZSM-5 zeolite samples. Linear discriminant analysis (LDA) was utilized to estimate degree of porosity based on near-infrared diffuse reflectance spectra. The textural properties (surface area and pore volume) of micro and mesoporous ZSM-5 samples were measured using N2 adsorption/desorption technique at 77 K and external surface area was calculated by t-plot as a reference method in this work. Several porous ZSM-5 samples with only microporous channels or mesoporous besides them were classified in terms of external surface area and meso pore volume derived from t-plot as “Micro” or “Micro + Meso” type samples. It was concluded that LDA using the PCA for feature selection is capable of generalization and could precisely predict the type of porosity in ZSM-5 zeolites.

CO2 adsorption on polyethylenimine-modified ZSM-5 zeolite synthesized from rice husk ash

Mesoporous ZSM-5 zeolite as the adsorbent supporting material was synthesized from rice husk ash (RHA), and then impregnated with polyethylenimine (PEI) for amine functional modification. A series of adsorbents (ZSM-5-PEI-X) with different PEI loading ratios were characterized by XRD, FTIR, TGA/DTG, nitrogen adsorption-desorption, SEM and EDX techniques. The measurement of the adsorption capacity at different temperatures was indicated that ZSM-5-PEI-30 had the highest adsorption capacity at 120 °C (1.96 mmol/g). The experimental data were fitted by adsorption kinetic models and isotherm models, indicated that fractional-order model and the Dual-site langmuir model can be used to describe the adsorption mechanism and predict the adsorption performance. The high CO2 adsorption selectivity and regeneration stability suggested that this adsorbent is a potential candidate in the adsorption and separation of CO2 in industrial flue gas.

PH-responsive mesoporous ZSM-5 zeolites/chitosan core-shell nanodisks loaded with doxorubicin against osteosarcoma

Oral or intravenous chemotherapy is an important strategy to treat metastatic cancer, but it may cause systemic toxicity for healthy tissue. Herein, we for the first time fabricated mesoporous ZSM-5 zeolites/chitosan core-shell nanodisks loaded with doxorubicin (ZSM-5/CS/DOX) as drug delivery systems against osteosarcoma. The mesoporous ZSM-5 zeolites exhibited disk-like shapes with thicknesses of 100nm and diameters of 300nm, and the mesopores with pore sizes of 3.75nm were originated from desilication treatment. The pH-responsive ZSM-5/CS/DOX nanodisks possessed a great drug loading efficiency of 97.7%, and their controlled release trends of DOX were fitted well with the Korsmeyer-Peppas model. The DOX could be efficiently released the ZSM-5/CS/DOX nanodisks after cellular endocytosis and induced cancer cells apoptosis. Moreover, the pH-responsive drug carriers led to efficient tumor inhibition with low side effects, especially cardiac toxicity, as confirmed by pharmacokinetic study, serological examination and H&E staining assays. Therefore, the ZSM-5/CS/DOX nanodisks are a promising pH-responsive drug carrier for targeted cancer therapy.

Acidic Mesoporous Zeolite ZSM-5 Supported Cu Catalyst with Good Catalytic Performance in the Hydroxysulfurization of Styrenes with Disulfides.

Development of highly active heterogeneous catalysts is an effective strategy for modern organic synthesis chemistry. In this work, acidic mesoporous zeolite ZSM-5 (HZSM-5-M), acidic-free mesoporous zeolite TS-1 (TS-1-M), and basic ETS-10 zeolite supported metal Cu catalysts were prepared to investigate their catalytic performances in the hydroxysulfurization of styrenes with diaryl disulfides. The effect of pore size and acidities of the supports, as well as the Cu species electronic properties of the catalysts on reaction activity were investigated. The results show that Cu+ and Cu2+ binded on HZSM-5-M show the highest activity and product selectivity for the desired β-hydroxysulfides compounds.

Fabrication of novel hierarchical ZSM-5 zeolite membranes with tunable mesopores for ultrafiltration

A series of novel hierarchical ZSM-5 zeolite membranes with tunable mesopore sizes have been prepared successfully by using amphiphilic organosilane 3-[(trimethoxysilyl) propyl]octyldimethyl-ammonium chloride (TPOAC) as the mesogenous template and part of the Si source. The effects of several synthesis parameters, such as the TPOAC/SiO2 ratio, synthesis temperature and crystallization time, on the microstructures and rejection performance of the hierarchical ZSM-5 zeolite membranes were systematically investigated. Multiple techniques, such as XRD, SEM, N2 adsorption techniques, TEM, IR, 13C MAS NMR and 29Si MAS NMR were employed for the characterizations. The filtration of dextran in water shows that the membranes have molecular weight cutoff (MWCO) ranging from 9500 to 943,000, corresponding to the molecular size in the range of 4.5–37nm. The sharp increase in the rejection of dextran with the increase of molecular weight indicated narrow pore size distribution of the membrane. These results show that the hierarchical mesoporous ZSM-5 zeolite membranes have a great potential for ultrafiltration with high performance.

Direct synthesis of ordered mesoporous ZSM-5 zeolites from in situ crystallization of carbonaceous SBA-15

Two types of ordered mesoporous ZSM-5 zeolites with different mesopores were synthesized by a two-step method. First, carbonaceous SBA-15 was produced by in situ carbonization of SBA-15/P123 composite. Then the obtained SBA-15/C composite was transformed into crystallized mesoporous ZSM-5 by impregnation TPAOH followed by steam-assisted crystallization. The final calcined samples synthesized with typical SBA-15/P123 precursor showed a wormlike morphology with the mean mesopore size of 4.6 nm, while samples synthesized with the addition of trimethylbenzene as swelling agent in the precursor exhibited the morphology of microsphere with the mesopore size of about 9.5 nm. Both two types of mesoporous ZSM-5 zeolites exhibited large surface area and mesopore structure. The steam-assisted crystallization (SAC) was performed with lower consumption of solvents. This two-step method may also be suitable for synthesizing other ordered mesoporous zeolites used as catalysts in some catalytic processes.

Adsorption of crystal violet dye onto a mesoporous ZSM-5 zeolite synthetized using chitin as template

HypothesisZSM-5 zeolite is an efficient adsorbent for several compounds. However, is a microporous material, and consequently, is little efficient for large dye molecules. In order to make ZSM-5 zeolite a mesoporous material with ability to adsorb dyes, the use of chitin (low-cost biopolymer) as template in the synthesis route can be an alternative. ExperimentsZSM-5 zeolites were synthetized using a nucleating gel as structure-directing agent for the material formation, followed by the chitin insertion (or not), homogenization and hydrothermal treatment. The obtained zeolites (ZSM-5 and chitin/ZSM-5) from these different methods were characterized. The potential of ZSM-5 and chitin/ZSM-5 zeolites to adsorb crystal violet dye (CV) was evaluated in batch mode, considering the effects of adsorbent dosage and pH. Equilibrium, thermodynamic and kinetic studies were also performed. FindingsThe use of chitin in the synthesis route provided the following improvements on the ZSM-5 structure: (i) the mesopores volume increased from 0.027 (ZSM-5) to 0.142cm3g−1 (chitin/ZSM-5); (ii) the pore diameter increased from 1.97 (ZSM-5) to 22.49nm (chitin/ZSM-5); (iii) the porosity was increased and the crystallinity was decreased. For both, ZSM-5 and chitin/ZSM-5, the CV adsorption was favored with adsorbent dosage of 2.0gL−1 and pH of 7.5. The pseudo-second order model was suitable to represent the adsorption kinetics and, the Langmuir model was adequate to represent the equilibrium. The maximum adsorption capacity increased from 141.8 (ZSM-5) to 1217.3mgg−1 (chitin/ZSM-5). The adsorption was spontaneous, favorable and endothermic.

Synthesis and applications of ordered and disordered mesoporous zeolites: Present and future prospective

Zeolites are microporous aluminosilicates that are used extensively for a wide variety of industrial applications. Applications of microporous zeolites are limited to transformations of small molecules due to the pore diffusion limitation imposed by the microporous network structure. In order to overcome this limitation, zeolites with inter-/intra-crystalline mesopores are generally preferred. This review article presents the details of various strategies for the preparation of mesoporous zeolites with inter-/intra-crystalline mesopores. A wide range of soft templates and additives is described in details for their use in the synthesis of mesoporous ZSM-5 and Beta zeolites. A brief report on the applications of mesoporous zeolites in various acid catalyzed reactions, involving large organic molecules, is provided in this article. Another important feature of this article is that it summarizes the applications of mesoporous zeolites in the electrochemical detection of various physiologically important biomolecules and organic/inorganic water pollutants. Further, the role of mesoporous zeolites based electrode materials for direct methanol fuel cell application is presented. Finally, the potential role of mesoporous zeolites in the field of biomedical engineering, particularly as a bone implant material, is summarized.

Enhanced Phenol Hydrodeoxygenation Over a Ni Catalyst Supported on a Mixed Mesoporous ZSM-5 Zeolite and Al2O3

Developing highly active catalysts for bio-oil hydrodeoxygenation is of great importance in the low cost production of conventional transport alkane fuels. Toward this goal, a Ni catalyst supported on mesoporous ZSM-5 zeolite mixed with 25 wt% γ-Al2O3 (Ni/Al-HMZSM-5) was designed for hydrodeoxygenation of phenol as model compound. For comparison, the catalytic activities of Ni catalysts on conventional microporous ZSM-5, mesoporous ZSM-5 and γ-Al2O3 were also investigated. It was found that almost complete phenol conversion (99.6%) was achieved over the Ni/Al-HMZSM-5 catalyst along with a high cyclohexane selectivity (98.3%) under a relatively mild condition (170 °C, 4 MPa H2). The open mesopores, stronger acid sites and synergism effect of Bronsted and Lewis acidities are jointly responsible for the excellent hydrodeoxygenation performance. In addition, it was shown that the catalyst was recycled several times with little loss of activity and selectivity.

Efficient Conversion of Light Cycle Oil into High-Octane-Number Gasoline and Light Olefins over a Mesoporous ZSM-5 Catalyst

Producing high-octane-number (ON) gasoline and light olefins is a promising route to valorize light cycle oil (LCO). In this work, the LCO was mildly hydrogenated and then catalytically cracked to produce high-ON gasoline and light olefins. Mesoporous ZSM-5 zeolite (meso-ZSM-5) was prepared and, for the first time, was applied in this process to crack the hydrogenated LCO (hydro-LCO). The catalytic performance of meso-ZSM-5 was evaluated in detail under different reaction temperatures and weight hourly space velocities (WHSVs). The results showed that, in comparison to less than 64 wt % hydro-LCO conversion over the conventional ZSM-5 catalyst, the novel catalyst exhibited excellent performance in cracking hydro-LCO with quite a high conversion of 84.8 wt %, affording a gasoline yield of 56.4 wt % and light olefin yield of 19.3 wt % at 560 °C and 10 h–1. In addition, the conversion behaviors of hydro-LCO components were analyzed over both the conventional ZSM-5 and meso-ZSM-5 catalysts. Finally, on the ba...

Synthesis of mesoporous ZSM-5 from rice husk ash with ultrasound assisted alkali-treatment method used in catalytic cracking of light naphtha

A series of mesoporous ZSM-5 zeolite was synthesized with ultrasonic assisted alkali-treatment technique and their catalytic activity was investigated in catalytic cracking of light naphtha. ZSM-5 zeolite was synthesized from rice husk ash without using any organic template. Effect of alkali-treatment conditions on physicochemical properties of synthesized zeolite was investigated with XRD, FESEM, TEM, N2 adsorption-desorption isotherm, NH3-TPD and TGA technique. It was found that ultrasound energy facilitates the creation of hierarchical structure of ZSM-5 during alkali-treatment. According to XRD analysis, zeolite structure was preserved after 20min ultrasonic assisted alkaline treatment. However, prolonged dessilication time led to the destruction of MFI zeolite structure. The synthesized ZSM-5 represented highly ordered hexagonal-shape morphology. With increasing alkali-treatment time, the plough land roughness appeared on the surface of zeolite. Comparison of the textural properties samples revealed that the mesopore surface area of alkali-treated samples increased considerably with the increase of ultrasonic assisted alkali-treatment time. Results from catalytic activity tests showed that ultrasound energy has great influence on the activity of ZSM-5. The sample had the highest activity after alkali-treated for 20min in presence of ultrasound energy which was due to their appropriate hierarchical structure.

Synthesis and catalytic characterization of ZSM-5 zeolite with uniform mesopores prepared in the presence of a novel organosiloxane

Intracrystal-mesoporous ZSM-5 zeolites of varying SiO2/Al2O3 molar ratios with different morphologies have been synthesized by employing a novel organosiloxane (OSO) as mesopore-directing template. In comparison to the previously reported ZSM-5 zeolites with mesoporosity, the mesoporous ZSM-5 zeolites obtained in this paper have high hierarchical factor (HF, 0.13–0.18), meaning that little microporosity has been consumed with abundant mesopores introduced within zeolite frameworks. The effects of tetrapropylammonium hydroxide (TPAOH), SiO2/Al2O3 molar ratios, crystallization temperature and crystallization time on the morphologies and textural properties of the products have been discussed in detail. The synthesized mesoporous ZSM-5 zeolites were characterized with X-ray diffraction (XRD), nitrogen sorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), nuclear magnetic resonance (NMR) spectroscopy, inductively coupled plasma (ICP) optical emission spectroscopy, the temperature-programmed desorption of NH3 technique (NH3-TPD) and thermogravimetric (TG)/differential scanning calorimetry (DSC) techniques. The outstanding hydrothermal stability of mesoporous ZSM-5 zeolites have been demonstrated by the hydrothermal treatment test. The Na+ ion-exchange test exhibits obvious superiority compared to traditional ZSM-5 zeolite. And the primary catalytic performance in reaction of cracking of 1, 3, 5-tri-isopropylbenzene also exhibits excellent conversion activity and products selectivity.

Synthesis of ZSM-5 zeolite from coal fly ash and rice husk: characterization and application for partial oxidation of methane to methanol

Indonesian fly ash (SiO2/Al2O3 mole ratio = 3.59) was used together with rice husk (SiO2 92%) as raw material for mesoporous ZSM-5 zeolite synthesis. Prior being used, coal fly ash and rice husk were subjected to pre-treatment in order to extract silicate (SiO44-) and aluminate (AlO45-) and to remove the impurities. Then the ZSM-5 zeolite were synthesized through hydrothermal treatment using two types of templates (TPAOH and PDDA). The as-synthesized ZSM-5 was characterized using FTIR, XRD, SEM-EDX, and BET. The result of FTIR showed peaks at 1250-950 cm-1 (vasymetric T-O), 820-650 cm-1 (vsymetric T-O), and at 650-500 cm-1 confirming the presence of the five number ring of the pentasil structure. The result of XRD showed the appearance of certain peaks in the position 2 theta between 7-9° and 22-25° indicative of ZSM-5 structure, but also showed the pattern of low intensity magnetite and hematite. The SEM image showed the rough surface of hexagonal crystals from ZSM-5 structure, indicative of mesoporosity in the structure. EDX result showed Si/Al ratio of 20, while surface area analysis gave SA of 43.16. The ZSM-5 zeolites then was modified with cobalt oxide through impregnation method. The catalytic activity as heterogeneous catalysts in partial oxidation of methane was tested. The result showed that hence the catalytic activity of ZSM-5 and Co/ZSM-5 from fly ash and rice husk were still inferior compared to the pro-analysis sourced-counterpart, they were potential to be used as catalyst in the partial oxidation of methane to methanol.

Enhanced Adsorption Desulfurization Performance over Mesoporous ZSM-5 by Alkali Treatment

The adsorption sulfur capacity and selectivity are two key challenges for adsorption desulfurization technology of FCC gasoline. In order to improve the above issues, the mesopores were first introduced into ZSM-5 zeolites by a NaOH alkali treatment method to reduce the diffusion limitations and increase the sulfur capacity, in which the effects of the alkali concentration, treatment time, and temperature on the pore properties of zeolites were well discussed. The desulfurization performance was tested in a fixed-bed reactor using model fuel. The results demonstrated that the alkali treatment time was the most influential factor for the sulfur capacity. The mesoporous ZSM-5 adsorbents prepared under the conditions of 0.5 M NaOH, 150 min, and 75 °C showed the maximal sulfur capacity, the breakthrough and saturation sulfur capacities of which were 14.00 and 17.46 mg of S/g of adsorbent, respectively. In addition, Ni2+ ions were exchanged into mesoporous ZSM-5 zeolites to enhance the sulfur selectivity. The ...

Catalytic performance of CoMo catalysts supported on mesoporous ZSM-5 zeolite-alumina composites in the hydrodesulfurization of 4,6-dimethyldibenzothiophene

Composite materials (AZ-M-x) were prepared by mechanically mixing the mesoporous zeolite ZSM-5 (MZSM-5) and γ-Al2O3. This composite was employed as a support for CoMo catalysts (CoMoS/AZ-M-x). The CoMoS/AZ-M-x catalysts show high activity (TOF=2.1–3.0×10−3s−1) in the hydrodesulfurization (HDS) of 4,6-dimethyldibenzothiophene (4,6-DMDBT) as compared to the CoMo catalyst supported on γ-Al2O3 (CoMoS/γ-Al2O3, TOF=1.9×10−4s−1), and the HDS activity increased with the MZSM-5 content in the composites. In contrast, the HDS activity of a mixture of microporous ZSM-5 with γ-Al2O3 supported CoMo catalyst is similar to that of the CoMoS/γ-Al2O3 catalyst. Compared with microporous ZSM-5, introducing MZSM-5 into γ-Al2O3 improves the mesoporous structure of the composites, which benefits mass transfer of the reactant molecules. Furthermore, MZSM-5 in the composites modifies their surface properties with abundant acidic hydroxyl groups, which can weaken the Mo-support interaction, leading to modifications in the morphology of the MoS2 phases to form multi-stacked MoS2 active phases on the CoMoS/AZ-M-x catalysts.

Novel Mesoporous ZSM-5 Zeolite with Disparate Morphologies Synthesized by a Double Long-alkyl-chain Organosilane Template

AbstractA novel hierarchical ZSM-5 zeolite containing two disparate morphologies was prepared by using a new organosilane surfactant with two long alkyl chains. Main crystal phase arrayed regularly and stacked in dense layers. However, the rest of crystalline phase was shaped like egg tarts.

Highly efficient and recyclable basic mesoporous zeolite catalyzed condensation, hydroxylation, and cycloaddition reactions

Crystalline mesoporous ZSM-5 zeolite was prepared in the presence of 1,4-diazabicyclo[2.2.2]octane derived multi-cationic structure directing agent. The calcined form of the mesoprous zeolite was treated with NH4OH to obtain basic mesoporous ZSM-5. Catalyst was characterized by the complementary combination of X-ray diffraction, N2-adsorption, electron microscopes, and temperature programme desorption techniques. Catalytic activity of the basic mesoporous ZSM-5 was systematically assessed using Knoevenagel condensation reaction for the synthesis a wide range of substituted styrene. Applications of the catalyst were investigated in the benzamide hydroxylation for the synthesis of carbinolamides and one-pot, multi-component condensation reaction for the synthesis of naphthopyrans. Finally, the catalyst was evaluated in the cycloaddition of CO2 to epoxide for the synthesis of cyclic carbonates. Recycling study shows that no significant decrease in the catalytic activity was observed after five recycles.

Partial oxidation of methane to methanol over catalyst ZSM-5 from coal fly ash and rice husk ash

Methane is one of the greenhouse gases that can be converted into liquid fuels such as methanol to retain most of the energy of methane and produce a cleaner environment. The conversion of methane to methanol using ZMS-5 represents a breakthrough in the utilization of methane. However, material sources for zeolite synthesis as catalyst usually are pro-analysis grade materials, which are expensive. Therefore, in this research, coal fly ash and rice husk ash were used as raw materials for mesoporous ZSM-5 zeolite synthesis. First, coal fly ash and rice husk were subjected to pre-treatment to extract silicate (SiO 4 4− ) and aluminate (AlO 4 5− ) and impurities separation. The ZSM-5 zeolite was synthesized through hydrothermal treatment using two types of templates. After ZSM-5 was synthesized, it was modified with Cobalt through impregnation method. The catalytic activity of both ZSM-5 and Co/ZSM-5 zeolites as heterogeneous catalysts in partial oxidation of methane were preliminary tested and compared with that commercial one. The result showed that the zeolite catalyst ZSM-5 from fly ash coal and rice husk ash has the potential to be used as catalysts in the partial oxidation of methane to methanol.

Effect of citric acid addition on the morphology and activity of Ni2P supported on mesoporous zeolite ZSM-5 for the hydrogenation of 4,6-DMDBT and phenanthrene

Preparing small, highly dispersed Ni2P particles is important for improving the hydrogenation ability of Ni2P. Here, Ni2P nanoparticles (approximately 4.3nm) on mesoporous zeolite ZSM-5 (Ni2P/MZSM-5-CA) were prepared using citric acid (CA) as an assistant agent. The formation mechanism of small Ni2P particles when CA was added was investigated by combining UV–vis diffuse reflectance spectroscopy, Fourier transform infrared spectroscopy, and temperature-programmed reduction with a transmission electron microscope and CO chemisorption. The results indicated that the formed CA–Ni complex with high viscosity favors the Ni precursor dispersed on the dried catalyst. After calcination, the released Ni species strongly interacted with surface acidic hydroxyl groups on MZSM-5, leading to the formation of Ni2P particles with small sizes and good dispersion under a reducing atmosphere. The reaction rate constants and TOFs over Ni2P/MZSM-5-CA (16.2×10−2μmolg−1s−1 and 9.7×10−4s−1) are much higher than over Ni2P/MZSM-5 (8.2×10−2μmolg−1s−1 and 8.3×10−4s−1) in 4,6-dimethyldibenzothiophene hydrodesulfurization. In addition, Ni2P/MZSM-5-CA catalyst shows higher activity than Ni2P catalyst without CA in phenanthrene hydrogenation.

A Mesoporous ZSM-5 Zeolite Synthetized by a Novel Double Long-Alkyl-Chain Organosilane Template

Abstract A ZSM-5 zeolite molecular sieve was prepared by using a new type of double long-alkyl-chain organosilane template. The structure of the acquired zeolite was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nitrogen adsorption–desorption measurement, which showed a piled circular sponge crystal morphology and contained mesopores around 4 nm in it.