Zeolite 4A Research Articles

Study of 4A and 5A zeolite as a catalyst material in a catalytic converter for NO emission reduction in a CI engine.

The major contribution to atmospheric air pollution is from the heavy vehicular emission. At present, it is rising at an alarming rate. These automotive pollutions can be reduced to a great extent by the exhaust gas after-treatment methods. Among these, catalytic converter (CC) is the major source to reduce regulatory emission in the internal combustion (IC) engine. Most catalytic materials work in some specific temperature ranges, and they are also costly. In this study, the zeolite 4A (ZSM 4A) and zeolite 5A (ZSM 5A) powder were converted into a solid mold and tested as a catalytic material in the converter. The experimental readings were taken with the fabricated CC at the exhaust with various loads (0, 4, 8, 12, and 16kg) in the single-cylinder Kirloskar 5.2kW diesel engine. Waste plastics were pyrolyzed into oil and blended with diesel in the 50:50 ratio of diesel plastic blend (DPB) for this study. Nitrogen oxide (NO) and hydrocarbon (HC) were reduced by 18% and 22% respectively for ZSM 5A and 12% and 16% respectively for ZSM 4A.

Evaluation of the H2S and NO adsorption and release capacity of PEG-zeolites and PEG-titanosilicates composites

The exogeneous delivery of hydrogen sulfide (H2S) and nitric oxide (NO) has proven to have several therapeutic effects. However, the development of porous materials to be used as drug carries, specifically as carriers of gaseous molecules, is still in its infancy. In here, we synthesized and characterized four polyethylene glycol (PEG) composites obtained from two different kinds of zeolites (4A and Y) and two titanosilicates (ETS-4 and ETS-10). The H2S and NO adsorption capacities are important aspects of the H2S/NO carriers, and they were determined for all the PEG-composites. Additionally, release studies of the H2S/NO loaded composites in aqueous solution at physiological pH revealed a longer NO release than their parent material while for H2S this was not observed, yet the % of released H2S is higher than the parent material. Cytotoxicity studies using HeLa cell line showed that PEG composites at 450 μg/mL have no toxicity. The results indicate that all PEG composites may have potential as NO-carrier, while for H2S only the 4A@PEG may be evaluated.

One-step plasma reforming of CO2[sbnd]CH4 into hydrogen and liquid fuels: The roles of Cu and Fe sites on products distribution

Low-carbon plasma-catalysis technology has shown emerging potential for direct conversion of CO2/CH4 into H2 energy and value-added oxygenates at low temperatures. Nevertheless, how to efficiently regulate the distribution of the products and further reveal the catalytic roles of the active sites in plasma-catalysis remains a major challenge. Herein, we exploited 5A zeolite supported catalysts with varied Cu/Fe active sites and further investigated the effects of Ar/H2O additives in this reaction to tune the products distribution. Comprehensive characterization together with the evaluation tests revealed that Cu0 species in Cu/5A was favorable to the formation of CH3OH (18.0%), and Fe2+ in Fe/5A promoted the CH3COOH (7.9%) production. Noted that the addition of Ar greatly enhanced the conversions of CO2 (30.3%) and CH4 (55.6%) and the H2O additive significantly improved the H2 selectivity (56.6%). Upon systemic in-situ DRIFTS and kinetic modelling, the synergistic conversion routes involving the crucial radicals adsorption process over the catalysts surface were proposed. This work provides new insights into the design of highly selective catalysts for tuning the products distribution in the plasma-catalytic co-conversion of CO2/CH4.

Performance of zeolite- and PCM-based cascade hybrid heat accumulator with cast thermal conductivity enhancers

The study tackles the issue of facilitating heat transfer in a newly designed versatile thermal energy storage (TES) unit that uses waste or renewable energy. The novel hybrid heat storage unit, consisting of a phase change material (paraffin) and zeolite (4A) deposits to be used for short-term or long-term storage, was constructed and characterised. Cast aluminium heat transfer enhancers were designed, manufactured by 3D printing with investment casting and then applied in order to shorten the charging time and to equalise the temperature distribution in the accumulator. This approach ensured both the exceptional flexibility of the process and the easy optimisation of the heat transporting surfaces’ shape and weight, resulting in improved thermal behaviour without severely limiting the volume of the storage medium. Honeycomb-based perforated inserts were chosen as the most effective heat transfer geometries for both deposits. The performance of the hybrid heat storage unit was evaluated during an analysis of cyclic work’s. The theoretical values of heat efficiency and energy storage capacity were calculated as 65.7% and 2.63 kWh, respectively (2.29 kWh for the zeolite chamber and 0.34 kWh for the PCM one). Future work may deal with adjusting the connection between chambers (e.g. limiting heat losses).

Effects of the ion-exchange sequence on the CO2 uptake and CO2–over–N2 selectivity of zeolite NaKA

The CO2 and N2 adsorption on small-pore zeolite |Na12-xKx|-A was hypothesized to be affected by the ion exchange sequence used for the zeolite preparation. Zeolites were prepared by ion exchange of a commercially available zeolite |Na12|-A (4A) and a zeolite |K12|-A (3A) composition prepared from zeolite 4A. The CO2 and N2 adsorption properties were studied experimentally, and the binary CO2-over-N2 selectivity was estimated from single-component adsorption data using the apparent Henry's law coefficients. It was observed that the level of CO2 adsorption was reduced by increasing the K content for both series of zeolite NaKA. Zeolite |Na12-xKx|-A-from-4A had the highest CO2 adsorption capacity (at 1 atm and 273 K) for a given K content. At low K content, zeolite |Na12-xKx|-A-from-3A had the highest CO2-over-N2 selectivity. At an intermediate K content, the zeolites prepared from 4A had the highest selectivity. These differences show that non-equilibrium processes during the ion exchange are important for the CO2 and N2 adsorption properties of the derived zeolites. As of now, we refrain from speculating whether they relate to the detailed positioning of K+ and Na+ cations in the local structure of the zeolite or to mass-transport-related concentration gradients of the cations in the structure. Irrespectively, it was observed that the ion-exchange sequence affects the CO2 and N2 adsorption properties of the zeolites, which could be of general importance when it comes to the tuning of the properties of cation-rich zeolites.

Adsorption dynamics of ethane from air in structured fixed beds with different microfibrous composites

Adsorption dynamics of ethane in two granular fixed beds and structured fixed beds with microfibrous composites was studied. 5A zeolite membrane 5A/PSSF (paper-like sintered stainless steel fiber) and microfibrous entrapped activated carbon (MEAC) composites were prepared by wet layup papermaking/sintering technique and in-situ hydrothermal method. Microfibrous composites were characterized by X-ray diffraction, scanning electron microscopy and N2 adsorption/desorption. Structured fixed beds were designed by filling granular adsorbents (5A zeolite or activated carbon) and microfibrous composites at the inlet and outlet of the beds, respectively. Effects of flow rate, bed height and structure on the breakthrough curves were investigated. The length of unused bed (LUB) was determined, and Yoon–Nelson model was used to fit the breakthrough curves. The experimental results showed ethane was effectively adsorbed on the granular adsorbents and microfibrous composites. Both composites could decrease the LUB values and enhance bed utilization. All breakthrough curves fitted well to Yoon–Nelson model, with correlation coefficient exceeding 0.89. The adsorption rate of ethane could be improved in the structured fixed beds, which showed an enhanced mass transfer efficiency for ethane adsorption. LUB values of structured fixed beds with 5A/PSSF composites were larger, the bed utilization values were lower, and the adsorption rate constants were higher than those with MEAC composites under the same conditions.

Fabrication of Pebax/4A Zeolite Nanocomposite Membrane to Enhance CO2 Selectivity Compared to Pure O2, N2, and CH4 Gases

The separation of carbon dioxide is essential for the environment. Using membranes to separate this gas is economical, but the weakness in permeability and mechanical strength has prevented their commercialization. Robeson proved that permeability and selectivity have the opposite relationship and provided an upper limit for pairs of gases. Worth to be mentioned that any membrane placed above this limit could be commercialized. Scientists proposed mixed matrix membranes to overcome this problem. These membranes contain two phases, polymer, and inorganic. This research focuused on membrane technology and aimed to prepare a membrane that has a good performance for CO2 separation and at the same time its cost is economical, so by adding a reasonable price zeolite available in the market named 4A to the Pebax1657 polymer and changing the operating conditions of the process, permeability and Selectivity was measured. Pebax polymer and 4A zeolite were selected as respectively the polymer and mineral phases for membrane fabrication. The fabricated membranes were evaluated by XRD, FT-IR, FE-SEM, BET, EDAX, TGA/DSC, and mechanical strength tests. Finally, the selectivity of CO2 compared to N2, O2, and CH4 improved by 53, 67, and 75%, respectively, and obtained a good position on the Robeson diagram.

Comparative study on the performance of two synthetic zeolite 4A on the removal of heavy metals from aqueous solution—effect of coal fly ash as Al and Si source

Comparative study on the performance of two synthetic zeolite 4A on the removal of heavy metals from aqueous solution—effect of coal fly ash as Al and Si source

The role of carbon dioxide and water in the degradation of zeolite 4A, zeolite 13X and silica gels

The degradation of desiccants is important in designing natural gas conditioning processes.

Study of simultaneous adsorption of ammonium and phosphate in waters by La-F4A zeolites prepared from spent FCC catalyst

The problem of resource disposal of massive spent fluid catalytic catalyst needs to be solved urgently. Thus an environmentally friendly, highly efficient and economical cost adsorbent used for nitrogen and phosphorus removal was prepared from spent fluid catalytic catalyst. A novel 4A zeolite adsorbent loaded with lanthanum hydroxide (La-F4A) was prepared by acid leaching pretreatment, alkali fusion roasting hydrothermal and co-precipitation method. And use La-F4A in the study of simultaneous adsorption of ammonia-nitrogen and phosphorus in water. Adsorption experiments were carried out under the condition that the primordial concentrations of PO4 and NH4+-N were respectively 1 & 10mg/L. La-F4A has an adaptive adsorption ability on NH4+-N and PO4 in the pH range of 4-9. When the temperature is 298K, the dosage is 1.0 g/L, the contact time is 240 min, and test water pH=7, the maximum adsorption capacities for NH4+-N and PO4 are 7.64 mg/g and 0.93 mg/g respectively. The behaviours accord with the pseudo-second-order adsorption kinetic model. The adsorption of PO4 conforms to the Langmuir isotherm model while NH4+-N conforms to the Freundlich isotherm model. Coexisting anions have almost no effect on the adsorption of PO4, coexisting cations have different inhibitory effects on the adsorption of NH4+-N. After four desorption cycles, the removal efficiency of La-F4A for NH4+-N and PO4 was 77% and 93% of the initial capacity. There are both chemical adsorption and physical adsorption in the process. The ammonium removal mechanism is the ion exchange between NH4+ and Na+ in the framework, and the phosphate removal mechanism is the ligand exchange between PO4 and hydroxyl to form LaPO4. La-F4A is regarded to be an excellent adsorbent for ammonium and phosphate removal.

Cost And Product Optimization of Upgrading Light Naphtha Using Pressure Swing Adsorption Method by Aspen Adsorption Simulation

Light naphtha is an organic compound produced from the distillation process that is often sold at a low price because of its poor performance, especially in the value of Research Octane Number (RON). The goal of this study was to improve the quality of naphtha to become a useful fuel with qualifying performance that is High Optimum Mogas Component (HOMC) by using the Pressure Swing Adsorption (PSA) method with the help of Aspen Adsorption simulations to find the most optimal combination of zeolite adsorbents (Beta and 5A) to use in the process. The principle of this quality improvement is to separate the compounds contained in naphtha that have low RON values from those that have high RON values so that the performance of naphtha that has gone through the adsorption process can be maximized. For this study, the RON target from HOMC is 95, while the value of RON for feed light naphtha ranges from 61-65. There are three compounds simulated in this PSA process, n-pentane and n-hexane as compounds that want to be separated because they have low RON values from iso-pentane which has a high RON value. Furthermore, after acquiring the combination of adsorbents that resulted in the products that have the highest RON, the economic potential of all variables was evaluated to get the most optimal process to use. The economic potential is also analyzed to find the profit of the PSA process. The most optimal results are obtained when the adsorbent configuration produces the product with the highest RON and produces high economic potential. The results showed that the most optimal adsorbent combination is to use 30% Zeolite Beta; 70% Zeolite 5A with product results having the highest RON of 84 and economic potential of US$ 114,410,163.92.

The effects of dry grinding and wet grinding on synthesizing iodosodalite

How to dispose of radioactive iodine waste in a green and safe way has become a hot spot for research institutions around the world. In this study, we mainly compare the effects of wet grinding - hydrolysis transformation - sintering (wet grinding) and dry grinding - cold pressing - sintering (dry grinding) on the synthesis of iodosodalite. The analysis results show that the particle size of 4A zeolite treated by wet grinding for 2.5 ​h is approximately 5.5 ​μm. The results of in situ XRD, infrared spectroscopy, and in situ Raman show that the effect of wet grinding and refining treatment is more obvious for iodosodalite synthesis at 900 ​°C. TEM-EDS shows that the morphology of iodosodalite prepared by the wet method is more intact. Based on the above results, it is demonstrated that the wet milling treatment method is more favorable for the synthesis of iodosodalite.

Evaluation of high‐performance adsorbents for separation of CO2 from industrial effluent gases

AbstractThe aim of this work is the investigation of several CO2 adsorbents such as three synthetic zeolites (4A, 5A, and 13X), a natural zeolite (clinoptilolite), an activated carbon (AC), and a metal organic framework (MOF‐MIL‐53) for the postcombustion CO2 capture via temperature‐pressure swing adsorption. The adsorbents were evaluated in terms of the CO2 adsorption capacity and performance during successive adsorption–desorption cycles at different conditions (1–6 bar and 120–180°C) using different mixtures of gases simulating a combustion process stream (N2/CO2/O2/CO). The 13X zeolite showed excellent adsorption capacity of 4.3 mmolCO2/g zeolite and very stable performance during successive cycles. © 2022 Society of Chemical Industry and John Wiley & Sons, Ltd.

Biogas upgrading by pressure swing adsorption using zeolite 4A. Effect of purge on process performance

The use of bio-methane as a fuel is an important alternative to reduce the emission of greenhouse gases. Pressure swing adsorption (PSA) processes using carbon molecular sieve adsorbents are industrial state-of-the-art technologies for biogas upgrading. Replacing the CMS adsorbent with a cheaper alternative can be a way to reduce costs for downscaling the technology to make it available to farms operating at low flows and avoiding large methane emissions to atmosphere.We have evaluated the use of zeolite 4A as a selective material that partially excludes (or strongly delays) CH4 adsorption. Adsorption equilibrium and kinetics (at zero-coverage) of pure gases (283, 303 and 323 K) was measured. Adsorption equilibrium was fitted with the multi-site Langmuir model and there is a difference of 3 orders of magnitude in diffusion constants. Binary breakthrough and a two-column PSA experiment were performed to validate a mathematical model. The model was used to determine good operating conditions with this adsorbent material. Bio-methane purity over 98 % was obtained at a recovery biome-thane of ∼ 90 %. These performance indicators were obtained in similar pressure conditions as commercial adsorbents used in industrial PSA units indicating that zeolite 4A is a viable alternative for biogas upgrading processes.

A novel hybrid treatment for pharmaceutical wastewater implying electroflocculation, catalytic ozonation with Ni-Co Zeolite 5A° catalyst followed by ceramic membrane filtration

The removal of veterinary antibiotics in pharmaceutical wastewaters become more challenging with modern-day technologies due to their persistent nature. In a sequence, the release of veterinary antibiotics containing wastewater such as Enrofloxacin (EFC) and Tylosin Tartrate (TT) in water bodies has increased the chance for bacteria to attain the antibiotic resistance genes and also moved to others via horizontal gene movement. As a result, the microbes become more resistant even to conventional antibiotics due to the growth of antibiotic resistance genes in microbes. Consequently, conventional treatment technologies just partially remove the pharmaceuticals from the wastewater and are not fully effective because they are not premeditated to remove antibiotics drugs. This alarming situation seriously threatens human well-being and aquatic life. Therefore, it is indeed important to develop an economical advanced oxidation treatment method for the efficacious treatment of pharmaceutical wastewater (PhWW). In the current study, a novel approach was adopted by implying Electroflocculation (EF), Catalytic ozonation (CO) in combination with novel catalyst Ni-Co-Zeolite 5A° followed by Ceramic membrane filtration (CMF). For the first time, in the current investigation, the studied hybrid process (EF + CO–CMF) using Zeolite 5A° coated with double metal salts of Nickel and Cobalt was applied as a catalyst in ozonation (O3) for the treatment of PhWW. Moreover, the removal of COD, BOD5, and turbidity was also studied and compared with national and international effluent quantity discharge standards. The obtained results exhibited that the combined EF + CO process has achieved removal efficiencies of 33 %, 93 %, 78 %, 45 %, and 60 % for EFC, TT, COD, BOD5, and turbidity respectively. Furthermore, the integration of CMF after EF + CO has enhanced the removal of pollutants up to the mark. It was revealed that the novel combined treatment method EF + Ni-Co Zeolite 5A°/O3–CMF has removed the EFC, TT, COD, BOD5, and turbidity of 97 %, 98 %, 90 %, 86 %, and 93 % respectively at optimum conditions (pH = 7.1 ± 0.2; treatment time = 30 min; EF voltage = 10 V; catalyst dose = 10 g/L; O3 = 1.1 mg/min). Additionally, it was observed that biodegradability (BOD5/COD ratios) enhanced from 0.48 to 0.60, and become easily biodegradable for further treatment. Henceforth, EF + Ni-Co Zeolite 5A°/O3–CMF treated wastewater has also complied with the Punjab Environmental Quality Standards (PEQS). Therefore, this novel hybrid treatment process may efficaciously apply at an industrial scale for the treatment of veterinary antibiotics containing PhWW.

Low-pressure adsorption of hydrogen isotopologues on LTA4A zeolites - A grand canonical Monte Carlo simulation study

Effective removal of the trace quantities of hydrogen and its isotopologues is crucial for the proper functioning of the tritium extraction system (TES) in the fuel cycle system of the fusion reactor. Zeolite molecular sieves of Linde Type A (LTA) framework are considered potential adsorbent materials for the cryogenic molecular sieve bed (CMSB) of the TES. However, the adsorption isotherm data of H2, HD, D2, HT, DT, and T2 on LTA 4A zeolites at low pressures (1–1000 Pa) and 77.4 K temperature is scarce in the literature. Grand canonical Monte Carlo (GCMC) simulations were performed to study the hydrogen isotopologues adsorption in the pressure and temperature ranges of operation of the CMSB of TES. The adsorption isotherms show that the equilibrium loading capacity is larger for T2, followed by D2 and H2 at 77.4 K. In the case of heteronuclear isotopologues, the loading capacity is larger for DT, followed by HT and HD under the same conditions of interest. The increase in the equilibrium adsorption capacity with isotopic mass could be attributed to the difference in the zero-point energies of the isotopologues. The effect of Si/Al ratio in the LTA zeolites on the cryosorption of hydrogen isotopes is investigated. The results show that, as the Si/Al ratio decreased, the equilibrium loading of the hydrogen molecules increased. The results obtained from this work are in good agreement with our experimental results and published data in the literature.

Utilisation of waste Cu-, Mn- and Fe-loaded zeolites generated after wastewater treatment as catalysts for air treatment.

Disposal of copper, manganese and iron is particularly problematic in wastewater of metallurgical and galvanization plants, the electronics industry and agriculture. On the other hand, volatile organic compounds (VOCs), emitted from industrial processes, transportation and consumer products are the main class of air pollutants. The study revealed the potential of waste metal-loaded zeolite, generated through wastewater treatment procedures, to be utilised as an effective VOC removal catalyst for air treatment. In the first step, we have evaluated the sorption performance of natural zeolite clinoptilolite (HEU type), and synthetic zeolite 4A (LTA type) for the simultaneous removal of Cu2+, Mn2+ and Fe3+ species from aqueous solution. By a detailed sorption study, we determined the optimum sorption conditions and maximum metal concentrations in wastewater that can be after treatment disposed of in rivers or municipal plants. The efficiency of both zeolites for metal immobilization was demonstrated for concentrations up to 5mg metals/1g zeolite. These waste Cu-, Mn- and Fe-loaded zeolites were thermally treated at 540°C before the second step, where we evaluated their catalytic performance in removing VOC. The thermally treated waste Cu-, Mn- and Fe-loaded natural zeolite clinoptilolite showed good catalytic performance in total toluene oxidation as a model VOC (conversion rate up to 96% at 510°C) and cycling stability (less than 15% drop in conversion rate in 4h). In contrast, this is not the case for thermally treated waste Cu-, Mn- and Fe-loaded synthetic zeolite 4A.

Simple Aminated Modified Zeolite 4A Synthesized Using Fly Ash and Its Remediation of Mercury Contamination: Characteristics and Mechanism

In this study, through simple ammonia impregnation, more amine functional groups could be introduced into the zeolite 4A synthesized using fly ash, which efficiently improved the mercury ion removal capacity of modified zeolites. The impregnation-modification mechanism of NH3·H2O, ammonium chloride, and silane coupling agent (KH792) for zeolite 4A, and the Hg2+ ion removal-efficiency by aminated zeolites, were studied and compared. Through ion exchange and hydroxyl reactions, NH3·H2O impregnation introduced the same kinds of nitrogen-containing groups into zeolite as KH792 grafting, which was more than the NH4Cl modification. The Hg2+ ion adsorption capacity of NH3·H2O-zeolite was higher than those of KH792-zeolite and NH4Cl-zeolite through ion exchange and the complexation of nitrogen-containing groups. When coexisting with Pb2+, Cu2+, and Zn2+ ions, the Hg2+ ion removal rate of NH3·H2O-zeolite was still higher than 99%. After five adsorption and desorption cycles, the Hg2+ ion removal rate of NH3·H2O-zeolite was 72.03%. When NH3·H2O-zeolite was added to the leaching of mercury-contaminated soil, the content of soluble mercury significantly decreased. Therefore, we synthesized a potential cheap and safe adsorbent using fly ash as the main raw material through the simple NH3·H2O impregnation modification for the treatment of mercury-contaminated water and soil.

Experimental Study of LiCl/LiBr-Zeolite Composite Adsorbent for Thermochemical Heat Storage

Adsorption-based thermochemical heat storage is a promising long-term energy storage technology that can be used for seasonal space heating, which has received significant amount of efforts on the research and development. In this paper, the heat storage capacity of composite adsorbents made by LiCl + LiBr salt and 3A zeolite was investigated. The basic characteristics of composite material groups were experimentally tested, and it was found that the adsorption composite with 15 wt% salt solution had excellent adsorption rate and adsorption capacity, which was considered as the optimal composite material. Furthermore, the heat storage density of the composite material could be as high as 585.3 J/g, which was 30.9% higher than that of pure zeolite. Using 3 kg of the composite material, the adsorption heat storage experiment was carried out using a lab-scale reactor. The effects of air velocity and relative humidity on the adsorption performance were investigated. It was found that a flow rate of 15 m3/h and a relative humidity of 70% led to the most released adsorption heat from the composite material, and 74.3% of energy discharge efficiency. Furthermore, an adsorption heat storage system and a residential model were built in the TRNSYS software to evaluate the building heating effect of such heat storage system. It is found that the ambient temperature will affect the heating effect of the adsorption heat storage system. The coefficient of performance (COP) of this model is as high as 6.67. Compared with the gas boiler heating system, the adsorption heat storage energy can replace part of the gas consumption to achieve energy savings.

Step-by-step desolvation enables high-rate and ultra-stable sodium storage in hard carbon anodes

Hard carbon is regarded as the most promising anode material for sodium-ion (Na-ion) batteries, owing to its advantages of high abundance, low cost, and low operating potential. However, the rate capability and cycle life span of hard carbon anodes are far from satisfactory, severely hindering its industrial applications. Here, we demonstrate that the desolvation process defines the Na-ion diffusion kinetics and the formation of a solid electrolyte interface (SEI). The 3A zeolite molecular sieve film on the hard carbon is proposed to develop a step-by-step desolvation pathway that effectively reduces the high activation energy of the direct desolvation process. Moreover, step-by-step desolvation yields a thin and inorganic-dominated SEI with a lower activation energy for Na+ transport. As a result, it contributes to greatly improved power density and cycling stability for both ester and ether electrolytes. When the above insights are applied, the hard carbon anode achieves the longest life span and minimum capacity fading rate at all evaluated current densities. Moreover, with the increase in current densities, an improved plateau capacity ratio is observed. This step-by-step desolvation strategy comprehensively enhances various properties of hard carbon anodes, which provides the possibility of building practical Na-ion batteries with high power density, high energy density, and durability.