Zeolite Composites Research Articles

Core-shell SAPO-34@ZSM-5 composite via in situ solid-solid transformation of pre-coating MCM-41 shell and its application in methanol-to-olefins

Hierarchically core-shell-structured SAPO-34@ZSM-5 composite zeolite was successfully achieved by an in situ solid-solid transformation of a pre-coating MCM-41 shell layer with the help of ZSM-5 seeds under a traditional hydrothermal crystallization route. As a result, a uniform nano-sized polycrystalline ZSM-5 shell closely grows on the core SAPO-34 microsphere, thus forming a desirable core-shell structured zeolite composite. Besides, the SAPO-34 core and the polycrystalline ZSM-5 shell are intimately connected through mesosilica substrates as a “bridge” which guarantees the integrity of the core-shell structure very well, even under harsh ultrasonic treatment at a high frequency. More crucially, this innovative method effectively overcomes the chemical and structural incompatibility between the core crystals and the shell zeolite during synthesis, and simultaneously avoids the collapse and dissolution of SAPO-34 crystals mainly derived from the shielding effect of MCM-41 shell layer under a highly alkaline gel precursor yielding ZSM-5. Furthermore, the methanol-to-olefins (MTO) was selected as a probe reaction so as to investigate the catalytic performance of the core-shell SAPO-34@ZSM-5. It is found that besides obtaining high light olefins yield (12.3% more than that on the reference catalyst), the catalytic lifetime over core-shell SAPO-34@ZSM-5 catalyst is greatly improved, about 3 times as long as that over the pristine SAPO-34 and 2.6 times as long as that on the corresponding physically-blended SAPO-34+ZSM-5. The superior catalytic performances on the core-shell SAPO-34@ZSM-5 can be attributed to the synergetic effects between SAPO-34 (core) and ZSM-5 (shell) including different framework structures, moderate acidic properties, and well-defined hierarchical architectures.

Synthesis of composite zeolite membrane by low-temperature water bath for efficient dynamic hardwater softening

In recent years, zeolite membrane has developed rapidly in the application of water treatment technology. However, the traditional zeolite membrane preparation process has the shortcomings of high temperature hydrothermal and other complex processes, which hinder its potential for large-scale industrial applications. In this study, a metakaolin/slag composite NaA zeolite membrane (GNaAM-20) on stainless steel substrate was prepared by composite geopolymer (metakaolin mixed with 20% slag) in a low-temperature water bath method, and GNaAM-20 was applied to the dynamic separation of Ca2+ from hard water. In this work, the mechanical strength (10.08 MPa) and crystallinity (92.13%) of composite zeolite membrane were enhanced by adjusting the slag content, so that a compact and higher removal efficiency zeolite membrane was prepared. The results showed that the GNaAM-20 had excellent acid resistance (pH = 1) with a removal efficiency of 92.03%, and the Ca2+ average removal efficiency by dynamic filtration after ten times of filtration (500 mL per filtration) was 91.2% using a 500 mg·L−1 Ca2+ solution. The maximum dynamic membrane adsorption capacity of GNaAM-20 was 102.54 mg·g−1. Compared with powder or gel adsorbents. GNaAM-20 virtually maintained its initial removal abilities after 5 regeneration cycles (average removal rate of more than 95%), and it had more significant advantages in terms of recycling and regeneration. Therefore, this study provides new ideas for achieving hard water softening and provides scientific guidance for industrial production.

Polycrystalline ZSM-5@Beta core–shell composites fabricated by a seed-directed approach: A catalyst to boosting light olefin production by ordered hierarchical cracking

Featuring engineerable reaction pathway, ordered hierarchical cracking over core–shell structured zeolites (core@shell) plays a pivotal role in achieving the high-efficient conversion of low-value oil fractions into important petrochemical building blocks such as ethylene and propylene. However, the synthesis of core@shell zeolite composites with specific desirable textures is technically challenging. Herein, a novel embryo seed-breeding (ESB) approach was developed to synthesize polycrystalline ZSM-5@Beta core–shell composites (pZ@B) for boosted light olefin production. For the first time, pZ@B composites composed of a polycrystalline ZSM-5 core and a submicron-sized Beta shell was reported, which shows enhanced inner-diffusion properties and improved hydrothermal stabilities than that of conventional ZSM-5@Beta composites. In pZ@B-catalyzed reations, bulky molecules undergone a preliminary cracking into intermediate products within the Beta shell, followed by the direct diffusion into the micropores of the ZSM-5 core where they could be cracked selectively into ethylene and propylene. Compared with physically mixed zeolites and hierarchical ZSM-5, pZ@B composites showed the highest conversion and yield of ethylene and propylene in the cracking reaction of both decalin and practical industrial heavy oil. The superior catalytic activity of pZ@B can be attributed to the high accessibility of acid sites and the ordered hierarchical cracking space derived from the core–shell structure.

Performance characteristics of desiccant rotor using metal organic framework material

A desiccant rotor is often adopted for dehumidification applications, owing to the increased importance of humidity control and energy saving in air conditioning and ventilation systems for buildings. In previous studies, silica gel, zeolite, and silica composites have been widely used in the desiccant rotor. However, it is difficult to further improve the dehumidification performance of a conventional desiccant rotor, owing to the inherent limitations of the desiccant material. In this study, a desiccant rotor using a metal organic framework (MOF) material was proposed and manufactured to improve the dehumidification performance under various operating conditions. The dehumidification and regeneration performance of the MOF desiccant rotor were measured and analyzed by varying the temperature, humidity, volumetric flow rate of the process air, and temperature of the regeneration air. Furthermore, the performance of the MOF desiccant rotor was compared to that of a conventional silica composite desiccant rotor. The MOF desiccant rotor showed 53% lower sensible energy ratio and 139% higher specific moisture removal capacity than the conventional desiccant rotor. In addition, empirical correlations were developed for performance predictions for the MOF desiccant rotor.

Erythromycin Scavenging from Aqueous Solutions by Zeolitic Materials Derived from Fly Ash.

Erythromycin (EA) is an antibiotic whose concentration in water and wastewater has been reported to be above the standard levels. Since the methods used so far to remove EA from aquatic environments have not been effective, the development of effective methods for EA removal is necessary. In the present study, fly ash (FA)-based zeolite materials, which have not been investigated as EA sorbents before, were used. The possibilities of managing waste FA and using its transformation products for EA sorption were presented. The efficiency of EA removal from experimental solutions and real wastewater was evaluated. In addition, the sorbents' mineral composition, chemical composition, and physicochemical properties and the effects of adsorbent mass, contact time, initial EA concentration, and pH on EA removal were analyzed. The EA was removed within the first 2 min of the reaction with an efficiency of 99% from experimental solutions and 94% from real wastewater. The maximum adsorption capacities were 314.7 mg g-1 for the fly ash-based synthetic zeolite (NaP1_FA) and 363.0 mg g-1 for the carbon-zeolite composite (NaP1_C). A fivefold regeneration of the NaP1_FA and NaP1_C showed no significant loss of adsorption efficiency. These findings indicate that zeolitic materials effectively remove EA and can be further investigated for removing other pharmaceuticals from water and wastewater.

Synthesis of a ZSM-5 (core)/SAPO-11 (shell) composite zeolite and its catalytic performance in the methylation of naphthalene with methanol.

In the present work, a ZSM-5 (core)/SAPO-11 (shell) composite was prepared by the hydrothermal method and characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), temperature programmed desorption of ammonia (NH3-TPD), and other characterization techniques. The catalytic performance of ZSM-5/SAPO-11 for the methylation of naphthalene with methanol was also studied. For comparison, the mechanical mixture was prepared through the blending of ZSM-5 and SAPO-11. The experimental results showed ZSM-5/SAPO-11 has been prepared with good crystallization, and exhibited a core-shell structure, with the ZSM-5 phase as the core and the SAPO-11 phase as the shell. The pore size of ZSM-5/SAPO-11 was between that of ZSM-5 and SAPO-11, and it had fewer acid sites than ZSM-5 and the mechanical mixture but more acid sites than SAPO-11. The excellent catalytic performance of ZSM-5/SAPO-11 was due to suitable pore size and acidity. The formation mechanism of the ZSM-5/SAPO-11 composite zeolite was also discussed.

Zeolites as sustainable alternatives to traditional tanning chemistries

A new material gaining industrial significance for sustainable leather is based on a composite of collagen and zeolite. The zeolite forms a 3D network structure covering collagen fibres, improving protein stability and creating material strength.

Improved catalytic performance in gas-phase dimethyl ether carbonylation over facile NH4F etched ferrierite.

Gas-phase dimethyl ether (DME) carbonylation to methyl acetate (MA) initiates a promising route for producing ethanol from syngas. Ferrierite (FER, ZSM-35) has received considerable attention as it displays excellent stability in the carbonylation reaction and its modification strategy is to improve its catalytic activity on the premise of maintaining its stability as much as possible. However, conventional post-treatment methods such as dealumination and desilication usually selectively remove framework Al or Si atoms, ultimately altering the intrinsic composition, crystallinity, and acidity of zeolites inevitably. In this study, we successfully prepared a series of hierarchical ZSM-35 materials through post-treatment with NH4F etching, which dissolved framework Al and Si at similar rates and preferentially attacked the defective sites. Interestingly, the produced pore systems effectively penetrated the [100] plane, offering elevated access to both the 8-membered ring (8-MR) and 10-membered ring (10-MR) channels. The physicochemical and acid properties of the pristine and NH4F etched ZSM-35 samples were comprehensively characterized using various techniques, including XRD, XRF, FESEM, HRTEM, Nitrogen adsorption-desorption, NH3-TPD, Py-IR, 27Al MAS NMR, and 29Si MAS NMR. Under moderate treatment conditions, the intrinsic microporous structure, acid properties, and crystallinity of zeolite were retained, leading to superior catalytic activity and stability with respect to the pristine sample. Nonetheless, severe NH4F etching disrupted the crystalline framework and created additional defective sites, bringing about faster deposition of coke precursors on the interior Brønsted acid sites (BAS) and decreased catalytic performance. This technique provides a novel and efficient method to slightly enhance the micropore and mesopore volume of industrially pertinent zeolites through a straightforward post-treatment, thus elevating the catalytic performance of these zeolites.

Comparative experiments on a new CaCl2-based composite material and zeolite 13X inside a thermochemical heat storage reactor

Thermal energy storage includes sensible, latent and thermochemical heat storage. The latter is particularly interesting because the heat is stored as a chemical potential, which reduces heat loss in long-term applications. The viability of thermochemical storage systems strongly depends on the energy density of the storage material. The development of high energy density materials is thus essential to achieve compact systems suitable for a wide range of applications. A new sol-gel composite material is investigated here: it is composed of CaCl2 dispersed within a matrix of silica and PEG-600 polymer. Composite materials containing CaCl2 have the highest storage capacities and seem to be the most promising candidates. The aim is to develop a composite that is both efficient and stable. The suitability of the material depends on the ability of the PEG to stabilise calcium chloride and prevent its deliquescence and leakage. The experimental results are compared to those obtained using zeolite 13X, which is a reference adsorbent material.

Investigation of Particle Breakdown in the Production of Composite Magnesium Chloride and Zeolite Based Thermochemical Energy Storage Materials

Investigation of Particle Breakdown in the Production of Composite Magnesium Chloride and Zeolite Based Thermochemical Energy Storage Materials

An adsorption agent based on chitosan–zeolite composite: environmental and radioactive liquid waste remediation

Chitosan–zeolite composite as a low-cost and efficient material in the removal of caesium in synthetic and liquid organic radioactive waste solutions.

Preparation of a microfibrous Fe/LTA zeolite membrane catalyst for acetone oxidation: effect of the preparation method

A novel Fe2O3-coated microfiber composite zeolite membrane catalyst (Fe/LTA/PSSF) was prepared for the catalytic combustion of acetone. The macropore structure of PSSF is conducive to improving the efficiency of mass and heat transfer.

Effect of Zeolite Concentration on Hydrogel Characteristics of Arrowroot-Based Starch-G-Poly(Acrylic Acid)/Zeolite Composite

This study aims to synthesize a hydrogel zeolite composite of arrowroot starch graft copolymerized with acrylic acid through a radical polymerization reaction in a water. Various scenarios were tested using different natural zeolite concentration to determine the impact on swelling/water absorption of the composite. The resulting product was a solid gel-the test results showed that the swelling increased as the ratio of starch to acrylic acid decreased. Increased starch concentrations generally lead to decreased water absorption (swelling capacity). Adding a zeolite improved swelling to some extent and the optimum zeolite concentration was 60%. The increased concentration of zeolite also hardened the hydrogel composite. The highest swelling in the hydrogel composite of starch-g-poly(acrylic acid)/zeolite 60% is 1056.25 g.g-1. FTIR analysis of functional groups was conducted to determine differences in the IR spectra of arrowroot starch, acrylic acid, hydrogels, zeolites, and composite hydrogel. Si-O signal appearing on the IR spectra of hydrogel composite with wave number 1030 cm-1 indicates that composite hydrogel with zeolite was synthesized

Upgradation of Eugenol to ASTM D 1655 standard Bio-Jet(A) fuel range hydrocarbons via hydrodeoxygenation process over Ru-Ni supported KIT-6/HZSM-5

A novel hierarchical Zeolite composite was successfully synthesized for bio-fuel application via catalytic hydrodeoxygenation of Lignin-Derived Phenolic Model Compound (LDPMC) in a downflow fixed bed reactor. The utilization of massive noble metals in the hydrodeoxygenation process in factories leads to an increase in the total cost of LDPMC technology. A fractional replacement of Ruthenium (Ru) by another transition metal Nickel (Ni), is a potentially effective method. The core asset of the novel synthesized catalyst displayed the advantageous properties of both micro- and mesoporous. This could be confirmed by the results of XRD, BET, and surface analyzing microscopes. The synthesis of Rux-Ni10-x/KIT-6-HZSM-5 (x = 2, 4 & 6) bimetallic-monometallic catalysts and their catalytic performance for hydrodeoxygenation of Eugenol are reported in the present study. The hierarchical Zeolite composite catalysts were synthesized by a wet-chemistry method. The active catalysts were characterized by ATR-IR, H2-TPR, NH3-TPD, HR-SEM, HR-TEM, XPS, and TGA techniques. The synthesized 2 %Ru-8 %Ni/KIT-6-HZSM-5 exhibited 100 % conversion with a maximum yield of 48.70 % of the complete deoxygenated product (Jet A range fuel) due to the synergistic effect between Ru and Ni on hierarchical Zeolite composite support and superior catalytic activity compared to the other synthesized catalysts with the highest metal dispersion. The stability and reproducibility of catalysts were steady even after 4 cycles. The Ruthenium and Nickel loaded hierarchical Zeolite composite support showed superior activity related to other reported catalysts even at atmospheric pressure under variable experimental conditions.

Removal of Indigo dye from aqueous solution using amidoximated acrylonitrile /Na-Y- Zeolite composite

Removal of Indigo dye from aqueous solution using amidoximated acrylonitrile /Na-Y- Zeolite composite

Step-By-Step Modeling and Demetallation Experimental Study on the Porous Structure in Zeolites

The organization of microporous space in zeolites is discussed. A new step-by-step model is proposed that explains the principles of organizing the hierarchy of microporous space at the stage of assembling zeolites from elements of minimal size: a primary building unit, secondary building units, tertiary building units or building polyhedra, a sodalite cage, and a supercage. To illustrate the stepwise hierarchical porous structure of nanomaterials, the following zeolites with small and large micropores have been selected as the model objects: sodalite (SOD, the maximum diameter of a sphere that can enter the pores is 0.3 nm) and zeolites of type A (LTA, the maximum diameter of a sphere that can enter the pores is 0.41 nm), type X, Y (FAU, the maximum diameter of a sphere that can enter the pores is 0.75 nm), and type BETA (the maximum diameter of a sphere that can enter the pores is 0.67 nm). Two-dimensional and three-dimensional modeling in 3Ds Max software was used. We believe that such an approach will be useful for developing ways to create complex zeolite compositions for specific applications, such as catalysis, where the geometry of the pores determines the size of the molecules entering the voids and computer modeling can play an important predictive role. This work takes a look at specific aspects of using the heat desorption method to study mesoporous materials with a BETA zeolite as an example and presents the results of experimental research into the characteristics of the porous structure of hierarchically structured zeolite materials (specific surface area 180-380 m2/g, external surface area 120-200 m2/g, micropore volume 0.001-0.1 mL/g).

Filter material based on zeolite-activated charcoal from cocoa shells as ammonium adsorbent in greywater treatment

• Filter Zeolite-Activated Charcoal from Cocoa Shells characterized by Porosity, Hardness, XRD and SEM EDX. • Filter with the best physical test is a filter with a composition of (75:25) % that is sintered at a temperature of 700°C. • Improved mesoporous characteristics coupled with ion-exchange significantly enhanced the ammonium removal capability of Zeolite-Activated Charcoal from Cocoa Shells. • Ammonium removal efficiency of Zeolite-Activated Charcoal from Cocoa Shells up to 68.25 %. A filter based on zeolite-activated charcoal cocoa shells has been made as an ammonium absorber in greywater. The two filter materials, Zeolite as matrix and activated charcoal of cocoa shells as filler, were first prepared in powder form with a size of 75 µm (200 mesh). The zeolite matrix was chemically activated using 1 M NaCl solution and dried at 100 °C for 24 hours, while the activated charcoal filler of cocoa shell was carbonized at 150°C for 1 hour. The filters were printed using a hydraulic press with a given mass of 5 tons for 10 minutes, with variations in the composition of zeolite and activated charcoal cocoa shell in the filter, namely (75:25) %, (80:20) %, (85:15) %, (90:10) %, (95:5) %, (100:0) %. The filters were then physically activated with sintering process at temperature variations of 700 °C, 800 °C, and 900 °C, for 4 hours. The physical and mechanical properties of the filters were characterized to determine the value of porosity, water absorption and hardness of the filters. Filter with the optimum physical test was found in the sample with the composition of (75:25) % which is sintered at a temperature of 700 °C. This filter is known to have with a porosity value of 53.01%, water absorption capacity of 53.10%. Meanwhile, the filter with the best hardness value was found in the sample with a composition of (100:0) % which was sintered at a temperature of 900°C with a value of 351.31 MPa. The test application of the filter as an ammonium absorber revealed that the filter was capable to reduce the ammonium concentration in greywater treatment up to 75.95 %.

Low-cost zeolitic carriers for delivery of hydroxychloroquine immunomodulatory agent with antiviral activity

The coronavirus pandemic prompted scientists to look for active pharmaceutical ingredients that could be effective in treating COVID-19. One of them was hydroxychloroquine, an antimalarial and immunomodulatory agent exhibiting antiviral activity. The anchoring of this drug on porous carriers enables control of its delivery to a specific place in the body, and thus increases bioavailability. In this work, we developed low-cost zeolitic platforms for hydroxychloroquine. The waste solution generated during zeolite production from fly ashes was used in the synthesis of Na-A and Na-X carriers at laboratory and technical scale. The materials were characterized by high purity and single mineral phase composition. The surface charge of zeolites varied from negative at pH 5.8, and 7.2, to positive at pH 1.2. All samples indicated good sorption ability towards hydroxychloroquine. The mechanism of drug adsorption was based on electrostatic interactions and followed the Freundlich model. Zeolitic carriers modified the hydroxychloroquine release profiles at conditions mimicking the pH of body fluids. The mode of drug liberation was affected by particle size distributions, morphological forms, and chemical compositions of zeolites. The most hydroxychloroquine controlled release at pH 5.8 for the Na-X material was noted, which indicates that it can enhance the drug therapeutic efficacy.

Comparative Review of Different Adsorption Techniques Used in Heavy Metals Removal in Water

The rising shortage of water resources and the need to provide water in many regions like Morocco around the world has been crucial and will become increasingly alarming in the future. Water bodies can be practically polluted or impaired by industrial, agricultural, and anthropogenic waste. Heavy metals are widely known environmental contaminants due to their toxicity, prevalence, and bioaccumulation. They build up in the environment, disrupting the food chains as chronic pollutants. In organisms, including humans, the deposition of possibly hazardous heavy metals poses a significant threat to health. This review paper highlights the present research on heavy metal removal, focusing on adsorbents and techniques accessible and feasible, such as adsorptive separation by substances, including a metal oxide, graphene, zeolite, and carbon-based composites. These techniques received a lot of acknowledgment due to their significant active surface area, high proportion of functional groups, increased chemical and thermal stability, and impressive adsorption efficiency and efficacy. The economic aspects and feasibility of adsorbents have also been presented.

Effect and Evaluation of Zeolite and Biohumus on Biological Indicators of Irrigated Seed-gray Soils

The effect of zeolite and biohumus on the biological activity of irrigated grass-gray soils under beans of the subtropical zone was studied. It was determined that the biological activity of the irrigated grass-gray soils changes depending on the growth phase of the bean, the applied biohumus and zeolite rate. Based on complex biological indicators (activity of enzymes, the number of microorganisms, abundance of carbon dioxide released from the soil, intensity of the nitrification process, intensity of decomposition of cellulose), bio-diagnostics of irrigated meadow-gray soils were given, an integral indicator of the biological condition of the soil was determined, and a biological assessment was carried out.
 The purpose of the work is to determine the effect of biohumus and zeolite on the biological activity of irrigated grass-gray soils used under the bean plant, and to conduct a biological evaluation based on complex biological indicators.
 The research object is irrigated meadow-gray soils (in WRB - Irragic Calsisols) of the subtropical zone, various doses of biohumus and zeolite, small bean-mung bean (Vigna Angularis) plant. Scheme of the experiment: 1. control (without fertilizer); 2. biohumus 5 t/ha; 3. zeolite 5 t/ha (clinoptilolite); 4. biohumus 5 t/ha + zeolite 5 t/ha; 5. biohumus 7.5 t/ha; 6. zeolite 7.5 t/ha; 4. biohumus 7.5 t/ha + zeolite 7.5 t/ha.
 Chemical composition of zeolite: Na2O-0.55; MgO-1.49; Al2O3-11.86; SiO2-66,0; P2O5-0.11; SO3-0.01; K2O -9.02; CaO-6.61; TiO2-0.51%; MnO-0.07; Fe2O3-3.77.
 Chemical composition of biohumus: humus 16%, pH 7, total azot (N) 3.2%, total phosphorus (P) 2.6%, total potassium (K) 2%, Ca 4.3%, Mg 0.6%, Fe 0.45%, Cu 0.5%, C:N 13.
 Mathematical-statistical calculation of the numbers obtained as a result of the research was carried out based on the Anova programma. The obtained results show a significant difference between the variants and compared to the control.