Zeolite Pores Research Articles

Cultivation of Microalgae Mixed Culture from Mahoni Small Lake UI Campus Depok using Zeolite Substrate with Varying Pb Concentration

Research on the cultivation of mixed cultures of Situ (small lake) Mahoni UI Campus Depok has been done. This research was a preliminary study to measure and compare the growth of Situ Mahoni mixed cultures microalgae grown in Bold's Basal Medium (BBM) with addition of zeolite and without addition of zeolite, and varying concentrations of heavy metal Pb. The concentrations of heavy metal Pb used were 0 ppm, 20 ppm, 40 ppm, 60 ppm, 80 ppm, and 100 ppm for two treatments. The results of this research were that the growth of mixed cultures with the addition of zeolite had the highest abundance of 8.800 cells/mL on day 5 (T5) at a Pb concentration of 40 ppm. Meanwhile, the growth of mixed culture without the addition of zeolite had the highest abundance of 21.700 cells/mL on day 10 (T10) at a Pb concentration of 60 ppm. The growth of microalgae mixed cultures in the medium without addition of zeolite was higher than using zeolite. The activation of zeolite pores causes the microalgae growth is relatively lower. This work aimed to study the growth of a mixed cultures microalgae in varying concentrations of Pb with and without the addition of zeolite

Synthesis and Structure Determination by 3D Electron Diffraction of the Extra‐large Pore Zeolite ITQ‐70

In this study, we present the synthesis, characterization, and structural analysis of a novel zeolite, ITQ‐70, using 3D electron diffraction tomography. This unique material was synthesized under alkaline conditions, employing tetrakis(diethylamino)phosphonium as organic structure‐directing agent, leading to the formation of a pure silica zeolite. ITQ‐70 is distinguished by its extra‐large pore apertures, which extend along all three axes and intersect one to each other. A notable feature of this zeolite is the presence of structurally ordered defects in very high concentration (38% of the silicon atoms). As a result, ITQ‐70 exhibits the lowest framework density (10.0 T/1000Å3) ever reported for any zeolite except RWY (7.6 T/1000Å3), which contains sulfur instead of oxygen connecting T‐atoms.

Investigation of hydrolysis of sugarcane bagasse into glucose over solid acid HSO3-ZSM-5 zeolite for fermentation to bioethanol

ABSTRACT In the pursuit of sustainable energy sources, biomass has emerged as a promising alternative to fossil fuels due to its renewability and carbon neutrality. This current work presents the application of solid acid zeolite catalyst for biomass hydrolysis into reducing sugar for fermentation. Sulfonated ZSM-5 zeolite was prepared by grafting sulfonic acid group on the surface and/or into the pores of porous ZSM-5 zeolite and characterized by several analyses. The as-synthesized HSO3-ZSM-5 zeolite was then investigated as a solid acid catalyst for the hydrolysis of alkaline pretreated sugarcane bagasse (SB). Containing sulfonic acid groups – a very strong acid – on the surface, HSO3-ZSM-5 zeolite presented high catalytic activity and high efficiency in the hydrolysis of SB biomass. When the hydrolysis was carried out under optimal conditions, approximately 106.8 g/L of reducing sugar including of glucose, xylose, arabinose, and cellobiose was recovered. 86.65% fermentable sugars could be achieved after catalytic hydrolysis, and 48.7% of SB in total was converted to reducing sugar and others. Moreover, this solid acid catalyst can be reused impressively several times with no significant loss in catalytic activity. The sugar hydrolyzate could be used for fermentative production of bio-ethanol. Results indicated the possibility of using solid acid zeolite in the hydrolysis of lignocellulose to generate sugars that can be further applied in biofuel or chemical manufacturing.

A hierarchical porous Fe3O4-COOH@H-ZIF-67 composite as magnetic solid-phase extraction adsorbent for benzimidazole pesticides

A hierarchical porous structural magnetic zeolite imidazolate framework-67 composite (Fe3O4-COOH@H-ZIF-67) was prepared through directly mixing the H-ZIF-67 and glutaric anhydride functionalized Fe3O4 nanospheres, of which the H-ZIF-67 was synthesized through a double template pore size regulation method. The successful preparation of Fe3O4-COOH@H-ZIF-67 composite was confirmed based on the material characterization using different techniques. The prepared composite was applied in the efficient removal of four benzimidazole pesticides (BZDs) in water using magnetic solid-phase extraction (MSPE) process. The results of static and dynamic adsorption experiments indicate that the adsorption of BZDs on Fe3O4-COOH@H-ZIF-67 follow pseudo-second-order kinetics, the Langmuir model fitted well with the adsorption data (R2 are all higher than 0.9969), and the maximum adsorption capacity for BZDs are 7.44–31.11 mg/g. Meanwhile, the adsorption mechanism study indicate that both hydrogen bonding and coordination play important roles during the adsorption process of BZDs. Finally, the developed MSPE method was combined with HPLC analysis and applied in the removal of BZDs from simulated pesticides wastewater. The removal rate was 82.76–96.18 %, and the treated samples met the requirements of the maximum residue limits of CBZ in the national standard GB 21523–2008. In addition, the adsorbent can be used at least three times and the extraction efficiency changed within 3 % after being stored in dry atmosphere at room temperature for 90 days. The results of this work manifested that Fe3O4-COOH@H-ZIF-67 composite can be used for removal and analysis of BZDs in complex samples.

Fabrication of yeast engineered porous 13X adsorbent layers for CO2 capture

This study investigates a novel environmentally friendly coating technique using yeast fermentation to obtain super porous Zeolite 13X adsorbent layers through freeze-drying technique for CO2 capture applications. Several mass ratios of sugar to yeast were used to control the porosity and pore sizes in the adsorbent layer. A unique peeling process was integrated to obtain foamy, hollow structures to have deeper layer accessibility of adsorbent for adsorption applications. These coated adsorbent layers were experimentally characterized as a function of the mass ratio of sugar to yeast and adsorbent solid fraction. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and Fourier-transform infrared spectroscopy (FT-IR) are used to analyze the coated layers. The void fraction for coated samples is found to vary between 0.48 and 0.56, making the samples applicable for adsorption applications. Adsorption performance experiments are performed to test the coated samples' performance compared to 13X powder. Due to their simplistic fabrication, cost-effectiveness, rapid pore formation, and high adsorption capacity, these porous 13X layers hold potential for large-scale fabrication and CO2 capture applications.

Non-linear Kinetic Model of Coke Deactivation in Methanol-to-Gasoline Conversion: Effects of Nano and Micro ZSM-5 Crystals

Methanol-to-gasoline conversion over ZSM-5 catalysts, a non-petroleum carbon fuel process, is significantly impacted by coke deposition, which deactivates the catalyst by blocking zeolite pores during the reaction and diffusion process. This study investigated the differences in coke species development and deactivation using a non-linear kinetic model, comparing microcrystalline ZSM-5 with longer pore lengths to nanocrystalline ZSM-5 with shorter pores, both tested at 350°C. Catalyst and coke were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), temperature-programmed oxidation (TPO), thermogravimetric analysis (TGA), and an elemental analyzer. Micro ZSM-5 initially achieved 99% conversion but rapidly dropped to 61% due to coke buildup, while nano ZSM-5 maintained over 98% conversion for 24hours before declining, highlighting the superior catalytic durability of shorter pores. Micro ZSM-5 showed faster coking, accumulating 7.19% coke with higher temperature-resistant graphitic coke, whereas nano ZSM-5 exhibited a lower coke buildup of 4.56%, forming primarily amorphous coke. A two-step non-linear kinetic model for soft and hard coke oxidation was applied, with the second-order model providing the highest correlation coefficient. The activation energy for coke decomposition was influenced by pore length, revealing distinct kinetic behaviors for hydrogen-deficient graphitic coke and amorphous coke. This study underscores the importance of zeolite pore structure on coke formation, deposition patterns, and catalytic durability, offering deeper insights into the methanol-to-gasoline conversion process.

Advanced Synthesis of Hierarchically Porous Zeolite Catalysts Utilizing Biomass Templates for the Catalytic Pyrolysis of Stearic Acid into Short-Chain Olefins

Advanced Synthesis of Hierarchically Porous Zeolite Catalysts Utilizing Biomass Templates for the Catalytic Pyrolysis of Stearic Acid into Short-Chain Olefins

Unraveling Molecular Diffusion Behaviors on the Acidic Sites of H‐ZSM‐5 Zeolite Using Time‐Resolved In Situ FT‐IR Technique

AbstractZeolites, renowned for their abundant crystalline structures and moderate acidities, have garnered significant attention in industrial chemical processes. Among them, the diffusion behaviors of various hydrocarbons within zeolite play a pivotal role due to their profound impact on product selectivity and separation efficiency. While acid sites are essential in determining the catalytic performance of zeolites, their effect on intra‐crystalline diffusivities has often been neglected in catalyst design. Herein, we employ a homemade time‐resolved in situ Fourier Transform Infrared (TR in situ FT‐IR) spectroscopy to investigate the intricate interplay between Brønsted acid sites and various probe molecules. Our study reveals that an augmentation in the density of Brønsted acid sites within H‐ZSM‐5 zeolites remarkably enhances the diffusivity of 1‐butene, in stark contrast to the behavior observed for iso‐butane. This contrasting effect in diffusivity is attributed to the distinct nature of interactions between alkenes and alkanes with Brønsted acid sites. Specifically, the π‐H interactions between alkenes and acid sites act as a driving force, propelling the alkene molecules forward through the zeolite pores. These findings offer valuable insights into designing tailored zeolites with specific acid site properties, controlling the transport behaviors of various probe molecules, and promising new avenues for catalysis and separation.

Cu nanoparticles immobilized in mesopores generated in zeolite for high-performing CO2 hydrogenation to methanol

Copper nanoparticles (Cu NPs) are commonly used as catalyst active components in CO2 hydrogenation reactions. However, they often lose their catalytic activity due to sintering in most reaction environments. This study explores a solution for Cu-supported catalysts used for methanol production from CO2 hydrogenation by fixing Cu NPs in the mesopores generated in zeolite. Mesopores were generated in NaY zeolite by partially dealuminating its framework. High-resolution (scanning) transmission electron microscopy (HR(S)TEM) and CO adsorption measurements confirm that the synthesized mesoporous zeolite-supported Cu NPs are highly dispersed and fixed within the mesopores. In comparison with conventional microporous zeolite-supported Cu NPs (2 wt%), Cu NPs (2 wt%, average size of 2.2 nm) in mesoporous zeolite increased methanol production from ∼26 mmolgCu−1h−1 to approximately 56 mmolgCu−1h−1 at 250 °C. By further modifying the mesoporous zeolite with Zr (2 wt%), Cu NPs increased in size, and the methanol production rate increased approximately 2.2 folds to 125 mmolgCu−1h−1 under similar conditions due to zeolite electronic modification and the newly formed Zr-zeolite/Cu interface. However, the addition of Zr significantly increased the Cu NP size and moved part of them out of the mesopores, lowering their stability. In situ DRIFTS experiments reveal CO2 hydrogenation proceeds through the formate route via a direct formation of dominantly carbonate (*CO3), which hydrogenates to formate (*HCOO) and traces of methoxy (*H3CO), and subsequently methanol (CH3OH). This study reports the design of active and stable catalysts for CO2 hydrogenation to methanol by engineering Cu NPs in zeolite pores.

Stability and Dynamics of Zeolite-Confined Gold Nanoclusters.

Nanoengineered metal@zeolite materials have recently emerged as a promising class of catalysts for several industrially relevant reactions. These materials, which consist of small transition metal nanoclusters confined within three-dimensional zeolite pores, are interesting because they show higher stability and better sintering resistance under reaction conditions. While several such hybrid catalysts have been reported experimentally, key questions such as the impact of the zeolite frameworks on the properties of the metal clusters are not well understood. To address such knowledge gaps, in this study, we report a robust and transferable machine learning-based potential (MLP) that is capable of describing the structure, stability, and dynamics of zeolite-confined gold nanoclusters. Specifically, we show that the resulting MLP maintains ab initio accuracy across a range of temperatures (300-1000 K) and can be used to investigate time scales (>10 ns), length scales (ca. 10,000 atoms), and phenomena (e.g., ensemble-averaged stability and diffusivity) that are typically inaccessible using density functional theory (DFT). Taken together, this study represents an important step in enabling the rational theory-guided design of metal@zeolite catalysts.

Tailor-made the ultrathin nanosheet and acid site accessibility of mordenite zeolite for carbonylation of dimethyl ether

Precisely tailored nano-morphology and crystal growth endures mordenite (MOR) zeolites with reduced internal diffusion resistance, enabling greater accessibility of existing acid sites to further stimulate catalysis. Controllable synthesis nanosheet MOR zeolite thinner than 20 nm along at least one dimension is highly attractive but remains great challenge. Herein, c axis along the [001] direction shortened MOR nanosheets with a thickness of 10–20 nm was synthesized. As expected, the mass transfer performance over the nanosheet sample is significantly improved by 2.5 times compared with the conventional nano-morphology. Furthermore, more Brønsted acid sites (BAS) can be induced into 8-membered ring (8-MR) pores in the nanosheet MOR zeolite. The conversion of dimethyl ether (DME) to methyl acetate over the ultrathin MOR zeolite is increased from 17.4 % to 71.7 % compared to that of the conventional nanoparticle. The DME conversion was stable at 70.0 % after reaction 80 h, when the acid sites located in 12-membered ring pores was poisoned by the pyridine molecule. Unexpectedly, we discovered that the desorption behavior of pyridine is also influenced by the accessibility of acid site, not only by the amount of BAS in 8-MR. The unique nanosheet structure with short c axis reduces the spatial stability of pyridine adsorbed on BAS in the 8-MR side pocket and the BAS in the 8-MR side pocket can be recovered at lower temperatures. Herein, a new insight into of DME carbonylation catalyzed by ultrathin nanosheet of MOR zeolite is revealed.

Solidifying High-Concentration Electrolytes Using Faujasite as Nanosized Porous Zeolite Additive for Solid-Type Batteries

Solidifying High-Concentration Electrolytes Using Faujasite as Nanosized Porous Zeolite Additive for Solid-Type Batteries

Electrolytic manganese residue and red mud co-treatment: Synthesizing zeolite X and adsorbing leaching solution from electrolytic manganese residue

Electrolytic manganese residue (EMR) and red mud (RM) are solid wastes from electrolytic metallic manganese and alumina production. These wastes continue to accumulate, causing significant environmental damage and resource waste. To solve these problems, porous zeolite X (ERZ) was synthesized with EMR and RM as the main raw materials. ERZ was then employed to adsorb the leaching solution generated during EMR purification. Also, an investigation was carried out to ascertain the most favorable parameters for the synthesis of zeolite, and the resulting ERZ was characterized. The results indicated that the synthesized ERZ exhibits excellent crystallinity, high thermal stability, and a large specific surface area. Next, solid-state NMR (SSNMR), XRD, and Raman spectroscopy were used to characterize the ERZ synthesis process: the structural units of X zeolite are β cages and 4Rs. Additionally, the study examined the adsorption impact of ERZ on impurity ions in the leaching solution, revealing that the adsorption mechanism is chemisorption. Furthermore, the effective regeneration of ERZ demonstrated its significant practical utility. To summarize, this study presents a new feasible way for effectively utilizing EMR and BA.

Structural stability and adsorption behaviour of CO2-loaded pure silica CHA and ITW zeolites upon compression

The present study investigates the structural stability and adsorption behavior of ultrahigh CO2-loaded pure-silica zeolites chabazite (CHA) and ITQ-12 (ITW) under high pressure conditions. To analyze these properties, we have utilized in situ synchrotron-based X-ray powder diffraction techniques. Lattice indexation provides information of the filling process and, through Rietveld refinements and Fourier recycling methods, we have been able to (i) determine the location and amount of guest carbon dioxide molecules within the cavities of pure-SiO2 CHA zeolite and (ii) tentatively determine that within the channels of the porous pure-SiO2 ITW framework. The filling of the zeolite pores with CO2 molecules was found to have a positive impact on the structural stability of both CHA and ITW under compression, which do not undergo pressure-induced amorphization up to 12.2 GPa and 15.9 GPa, respectively. Interestingly, low compressibility takes place in CHA zeolite below 4 GPa during CO2 loading and a second-order phase transition occurs in CO2-filled ITW zeolite at 2.1 GPa. These results highlight the influence of CO2 adsorption on the compressibility behavior of these zeolites. Overall, our study provides detailed insights into the structural behavior of CO2-loaded CHA and ITW under high pressure and allows comparison with other pure silica zeolites described in the literature.

Encapsulation of cobalt molybdate on modified hierarchical porous TS-1 zeolite catalyst for efficient oxidative desulfurization of fuel

Morphological modulation of heterogeneous catalysts has been shown to be a useful strategy for adjusting the concentration or intrinsic activity of active sites and their catalytic activity in catalysis. Herein, a hierarchical porous TS-1-supported cobalt molybdate catalyst (CoMoO4/TS-1-DR) was obtained through a facile dissolution-regrowth strategy. In an oxidative desulfurization reaction using O2 as the oxidant, the as-prepared catalyst demonstrated exceptional performance compared to the supported catalyst prepared via the impregnation method due to the bimodal pore architecture presented. Moreover, in situ CoMoO4 synthesis lowers active site leaching, thus showing better reaction stability. After 7 recycles, the removal rate of DBT still remained at 88.8%. This work offers a generic in situ encapsulation strategy for designing hierarchical porous zeolite catalysts and the synthesis of loaded metal oxides.

Cobalt-promoted palladium confined in HZSM-5 zeolite for toluene storage and oxidation capacity in humid environment

Although oxide-zeolite bifunctional catalysts with storage and oxidation capacity was efficient for VOCs removal, the inevitable moisture in the air usually harms the catalysts performance. Herein, cobalt was in situ confined with palladium in HZSM-5 by a one-pot hydrothermal method and significantly improved the storage and oxidation abilities in humid air. The optimal Pd0.90Co0.10@Z5 catalyst showed a considerable toluene storage capacity of 76.8 mg/g (100 ppm toluene/humid air, GHSV=60,000 h−1), and the best oxidation activity (600 ppm toluene/humid air, GHSV=60,000 h−1, TOFPd = 15.5 × 10−3 s−1 at 200 °C). Pd0.90Co0.10@Z5 formed an intrapenetrated mesoporous structure with the smallest Pd clusters of dAV=2.6 nm. The synergistic effect between palladium and cobalt promoted electron transfer and Pd0.90Co0.10@Z5 had the highest Pd2+/Pd0 ratio of 3.50. Co2+ can activate water to form Co(OH)3 and provide an additional ·OH oxidation pathway, ·OH and reactive oxygen species (O*) together promote the deep oxidation of intermediates. This work provides a novel approach that bimetallic collaboration combined with porous zeolite can improve the catalytic performance and water resistance.

Multi-mode luminescence anti-counterfeiting and visual iron(Ⅲ) ions RTP detection constructed by assembly of CDs&Eu3+ in porous RHO zeolite

Carbon dots (CDs)-based composites have shown impressive performance in fields of information encryption and sensing, however, a great challenge is to simultaneously implement multi-mode luminescence and room-temperature phosphorescence (RTP) detection in single system due to the formidable synthesis. Herein, a multifunctional composite of Eu&CDs@pRHO has been designed by co-assembly strategy and prepared via a facile calcination and impregnation treatment. Eu&CDs@pRHO exhibits intense fluorescence (FL) and RTP coming from two individual luminous centers, Eu3+ in the free pores and CDs in the interrupted structure of RHO zeolite. Unique four-mode color outputs including pink (Eu3+, ex.254 nm), light violet (CDs, ex.365 nm), blue (CDs, 254 nm off), and green (CDs, 365 nm off) could be realized, on the basis of it, a preliminary application of advanced information encoding has been demonstrated. Given the free pores of matrix and stable RTP in water of confined CDs, a visual RTP detection of Fe3+ ions is achieved with the detection limit as low as 9.8 μmol/L. This work has opened up a new perspective for the strategic amalgamation of luminous guests with porous zeolite to construct the advanced functional materials.

Improvement of the Oxidative Desulfurization Performance Using MoO3/CuO‐Modified Hierarchical HY Zeolite

AbstractThe presence of sulfur compounds in the chemical industry poses significant environmental and economic problems, including endangering human and animal lives and damaging equipment. For this purpose, hierarchical HY zeolite (Hie‐Y) with a SiO2/Al2O3 molar ratio 10 was successfully synthesized through sequential desilication‐dealumination using NH4OH treatment. A weak alkaline media with surfactant cetyltrimethylammonium bromide (CTAB) facilitates mesoporosity formation and preserves the zeolite structure. Metal oxide (CuO, MoO3) ‐ hierarchical HY zeolite nanocomposites have been prepared by one or a combination of 3 methods: 1) ion exchange, 2) precipitation, and 3) calcination. The obtained catalysts were characterized using XRD, FT‐IR, FESEM, UV‐Vis, EDS, and BET techniques. The formation of a hierarchical structure is associated with structure preservation, but partial destruction occurs based on the entering Cu in the zeolite pores. These catalysts have been studied in the oxidative desulfurization (ODS) reaction. Several parameters, including temperature, catalyst amount, DBT concentration, and reaction time, were evaluated in ODS using the Taguchi Design of Experiments. Catalytic activity order was obtained as Y<Hie‐Y<Hie‐Y/CuO<Hie‐Y/MoO3<Hie‐Y/MoO3/CuO. Results indicate an activity increase for the Hie‐Y/MoO3/CuO hierarchical structure owing to synergistic effects of secondary mesoporosity and metal oxides. The catalyst was recoverable and reused for five consecutive runs with preservation of catalytic activity.

PP upcycling employing FCC spent catalyst: The role of contaminants, atmosphere and pressure

Innovative and sustainable approaches are being pursued to convert plastic waste into high-value fuels, particularly without using noble metal catalysts or external hydrogen sources. In this scenario, we explored the utilization of a spent fluid catalytic cracking (FCC) catalyst (ECAT), aiming to enhance the yield and quality of products through catalytic cracking of Polypropylene (PP) under different reaction conditions. Under a 20 bar H2 atmosphere, ECAT efficiently cracked PP into alkanes (71.6 %) and aromatics (25.5 %), with minimal alkenes (2.2 %) production. Similarly, under a 20 bar N2 atmosphere, ECAT achieved comparable conversion levels, producing mainly saturated hydrocarbons, which was intriguing. However, tests conducted at 1 bar N2 pressure showed that PP conversion remains unaffected but presents higher olefins’ yield and lower aromatics than ECAT. Thus, pressure seems to favor aromatization and in situ hydrogen transfer. By comparing the performance of ECAT with commercial CBV 712 zeolite, we propose that PP acts as an internal hydrogen source, eliminating the need for external supply improving efficiency and selectivity. Interestingly, mechanistic insights suggested that dehydroaromatization and hydrogen transfer within zeolite pores were dominant, and pressure (H2 or N2) could have helped it. In addition, contrary to previous studies that claim that metal contaminants in ECAT are essential for the hydrogenation process, our findings suggest that for this particular ECAT composition, we do not observe any boost in alkane yield due to the presence of these metals. Hence, our study comprehensively evaluates different strategies that can be employed to promote PP upcycling promoted by ECAT.

Sulfonic Acid-Functionalized Tetraphenylethylene-Amplified Electrochemiluminescence by Regulating π-π Interaction.

The electrochemiluminescence (ECL) effectiveness of the tris(bipyridine) ruthenium(II) (Ru(bpy)32+) system is hampered by aggregation-caused quenching (ACQ) in optoelectronic systems as a result of π-π accumulation of the aromatic ring structure. In this work, a negatively charged tetraphenylvinyl molecule (TPE-2SO3Na, TPE-4SO3Na) was synthesized to modify the electrode interface, and the π-π accumulation between Ru(bpy)32+ molecules was transformed into the π-π interaction between Ru(bpy)32+ and TPE molecules. Interestingly, the ECL signal intensity of the Ru(bpy)32+-tripropylamine (TPA) system in the presence of TPE-2SO3Na was increased by about 15 times due to the π-π action and electrostatic action. In comparison with traditional physical packaging with porous zeolites, metal-organic frameworks (MOFs), and covalent organic frameworks (COFs), the fabricated electrode interface modification strategy was simple and efficient to avoid π-π accumulation in aqueous solutions. Our success will inspire other researchers to investigate the supramolecular interaction (π-π interaction, electrostatic interaction, hydrophilic interaction, and host-guest interaction) at the electrode interface to amplify the ECL intensities of Ru(bpy)32+.