Absence Of Organic Templates Research Articles

Fabrication of hydrophilic and durable Beta zeolite membranes for dehydration of fuel n-butanol by adjusting Al spatial distribution

Highly hydrophilic and durable Beta zeolite membranes with high aluminum (Al) spatial distribution were synthesized on inexpensive α-alumina supports via an organic template-free synthesis gel. In the absence of organic templates, the Al spatial distribution of Beta zeolite membrane crystal was regulated by the synthesis parameters such as the Al2O3/SiO2 ratio, alkalinity, H2O/SiO2 ratio and crystallization temperature, and the crystal morphology, Si/Al ratio and dehydration performance of the membrane could be further effectively controlled. Under optimal synthesis conditions, the prepared Beta zeolite membrane had an excellent separation factor of over 22,000 and a high permeation flux of 3.02 kg m−2 h−1 in the case of a 90 wt% n-butanol/water mixture at 75 °C. The high-performance Beta zeolite membrane was applied for continuous dehydration to obtain anhydrous n-butanol (99.9 wt%) from a 90 wt% n-butanol/water mixture. Furthermore, Beta zeolite membranes showed long-term acid stability in pervaporation dehydration of a 90 wt% n-butanol/water mixture with a pH value of approximately 2.0 at 75 °C for 192 h, indicating that these membranes by adjusting Al spatial distribution exhibited excellent hydrophilicity and acid resistance, which had a broad promising prospect of industrial applications for dehydration separation of acid-containing organic solvents.

Radicalized seeds-assist route for the rapid synthesis of zeolite ECR-1 in the absence of organic templates

Several different types of seeds have been introduced into the organic template-free synthesis of zeolite ECR-1. The corresponding crystallization process was affected by the structural properties of added seeds. A radicalized seeds-assist route for the rapid synthesis of zeolite ECR-1 in the absence of organic templates is demonstrated. The radicalized zeolite ECR-1 seeds can accelerate the induction and growth period of crystallization simultaneously. The crystalized zeolite ECR-1 products were characterized by X-ray diffraction, scanning electron microscopy, X-ray fluorescence, nitrogen adsorption-desorption and temperature-programmed desorption of ammonia. Compared with those synthesized in the presence of normal seeds, the zeolite ECR-1 products obtained via radicalized seeds-assist route exhibited higher crystallinity, consumed shorter crystallization time and presented a better catalytic performance in iso-butane cracking reaction.

Organotemplate-free synthesis of Al-rich ZSM-35 and ZSM-22 zeolites with the addition of ZSM-57 zeolite seeds

An organotemplate-free synthesis of Al-rich ZSM-35 (Si/Al ratio at about 5) and ZSM-22 (Si/Al ratio at about 20) zeolites has been successfully shown with the addition of ZSM-57 zeolite seeds in the absence of organic templates.

Accelerated synthesis of Al-rich zeolite beta via different radicalized seeds in the absence of organic templates

Abstract The radicalized seed strategy is introduced into the synthesis of Al-rich zeolite Beta without any organic templates. The different radicalized seeds milled for varied times (15 min, 30 min, 1 h, 2 h, 4 h) have been systematically investigated. By performing X-ray diffraction, Raman spectroscopy and electron paramagnetic resonance, the changes in seed structures and signals of radicals were characterized. Compared with the crystallization products synthesized in the presence of normal seeds, those synthesized in the presence of radicalized seeds milled for 30 min exhibited higher crystallinity, higher yields and larger BET specific surface areas and consumed shorter crystallization time. In the radicalized seed strategy, relatively complete ordered structures of seeds and generation of more free radicals are necessary to reach better acceleration effect.

Potassium-directed sustainable synthesis of new high silica small-pore zeolite with KFI structure (ZJM-7) as an efficient catalyst for NH3-SCR reaction

High silica small-pore aluminosilicate zeolites such as SSZ-13 have been commercially applied in selective catalytic reduction of NOx with NH3 (NH3-SCR), but their syntheses usually require the use of organic templates, which are environmentally unfriendly. Solution for this problem is sustainable synthesis of high silica small-pore zeolites in the absence of organic templates. One of examples is 8-membered ring aluminosilicate KFI zeolite, which is always Al-rich (Si/Al<4, KFI-4.0) in conventional synthesis. In this report, inspired by high throughput calculations, we successfully prepared new high silica small pore zeolite with KFI structure (Si/Al>5, designated as ZJM-7) in the presence of K+. Interestingly, even after hydrothermal treatment at 850 °C for 12 h, Cu-ZJM-7 catalyst still shows excellent performance in the NH3-SCR reaction. The combination of sustainable synthesis and excellent catalytic properties of ZJM-7 zeolite might provide a good opportunity for developing highly efficient and low-cost SCR catalysts in the future.

Cost-effective and facile one step synthesis of ZSM-5 from silica fume waste with the aid of metakaolin and its NOx removal performance

The disposal of powdery silica fume waste has become an urgent environmental problem, the synthesis of zeolitic materials using silica fume is a commendable remedy to this crisis. In this study, a cost-effective and facile one-step strategy was proposed for the first time for hydrothermal synthesis of ZSM-5 zeolite using silica fume waste with the aid of inexpensive metakaolin in the absence of organic templates. This method allowed the total transformation of silica fume into ZSM-5 which exhibited similar characteristics to those obtained from conventional chemical reagents. The as-synthesized ZSM-5 under the optimized condition was used to prepare Ni, Cu and Zn/ZSM-5 catalysts by means of ion exchange and calcination treatments for NOx removal by NH3-SCR, and they exhibited high NO conversion of 92, 100, and 95%, respectively. This study would be a promising candidate for cost-effective and environment friendly synthesis of zeolite using silica fume waste in large scale.

Facile and seed-direct synthesis of pure EUO zeolite with enhanced catalytic performance

The preparation of pure EUO zeolite under conventional conditions usually takes more than three days, limiting the application of the EUO zeolite. It is widely acquainted that the seed-assisted synthesis of zeolites without organotemplates is inexpensive, environmentally-friendly and lead to Al-rich products. However, synthesis with EUO seeds in the absence of organic-templates always leads to the formation of impurity phases. In this work, EUO zeolite (s-EUO) is successfully obtained by seed-directed synthesis without organotemplates. This is the first seed- directed synthesis of pure EUO zeolite with special Al source. Physicochemical characterization results show that the synthesized s-EUO zeolite exhibits high crystallinity and high specific surface area, and contains uniform crystals and plenty acidic sites. The s-EUO crystallization (by this method) occurs in a considerably shorter time (18 h) and in a more mild condition (160 °C, static state), compared to that of the conventional EUO zeolites (c-EUO, 72 h at 180 °C, at rotation) in the presence of organotemplate. Moreover, the catalytic performance of the H-form of the s-EUO zeolite is enhanced to that of the c-EUO zeolite for m-xylene isomerization, confirming the NH3-TPD results.

Application of Cu-FAU nanozeolites for decontamination of surfaces soiled with the ESKAPE pathogens

Antimicrobial resistance is a global threat with catastrophic forecasts in terms of human and economic losses. The so-called ESKAPE pathogens (Enterococcus species, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumanii, Pseudomonas aeruginosa and Enterobacter species) represent a range of species of particular concern because they cause many serious hospital infections, and can show resistance toward available commercial antibiotics. Copper-containing zeolite nanocrystals (10–30 nm) with FAU-type structure (Cu-FAU), in the form of stable colloidal suspensions, were prepared at high yield in the absence of organic templates and studied for their activity against ESKAPE microorganisms. The materials were active against all six ESKAPE species. The survival of Staphylococcus aureus, Klebsiella pneumoniae and Pseudomonas aeruginosa on stainless-steel coupons after direct treatment with the Cu-FAU zeolite suspensions was determined quantitatively. Complete decontamination (5-log reduction in bacterial counts) was achieved within 20 min for P. aeruginosa, and within 10 min for the K. pneumoniae and S. aureus. This result is significant, particularly for sanitization of surfaces in healthcare settings, with the potential to initiate a new direction of research to help address the global antimicrobial resistance threat.

Adsorption of carbon dioxide and methane on nanosized sodalite octahydrate zeolite

ABSTRACTNanosized sodalite octahydrate zeolite has been developed using a crystallization room temperature in the absence of organic templates. The best aging time found was 120 h and in this time the nanosized sodalite octahydrate zeolite is formed. The samples were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-Transform Infrared (FTIR) spectroscopy, x-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and N2 adsorption–desorption isotherm. The equilibrium adsorption capacities of pure gases CO2 and CH4 were measured at 298 and 308 K up to 20 bar on both powder and granules of sodalite octahydrate zeolite. With increasing temperature, the adsorption capacity decreases for both sodalite octahydrate zeolite powder and granules. The selectivity of CO2 at 308 K over CH4 was 6.53.

The synthesis of analcime zeolite nanoparticles using silica extracted from stem of sorghum Halepenesic ash and their application as support for electrooxidation of formaldehyde

In this work, a free template method is used to synthesize nanostructured analcime (ANA) zeolite from natural source and the prepared zeolite is applied as substrate to fabricate a modified electrode. To this aim, ANA zeolite nanoparticles are synthesized by hydrothermal method using amorphous silica extracted from stem of sorghum ash (SSA) with approximately 92.34% purity in the absence of organic template. The effects of different parameters such as Si/Al ratio, heating time, temperature and stirring time on synthesis and crystallinity of zeolite are optimized. The synthesized zeolite is characterized using X-ray diffraction, Fourier-transform infrared and scanning electron microscopy (SEM) techniques. SEM shows that ANA zeolite nanoparticles appear as spherical particles contains some smaller nanoparticles which arranged in regular pattern to each other. Also, some fibers consist of nanoparticles in range of 30–48 nm are observed.The modified carbon paste electrode (CPE) is prepared based on ANA modified with Ni species (Ni/ANACPE). The electrochemical oxidation of formaldehyde is studied at Ni/ANACPE in alkaline solution. From cyclic voltammetry studies, it is shown that Ni/ANACPE can facilitate the oxidation of formaldehyde compared to CPE. The effects of some parameters such as scan rate of potential, concentration of formaldehyde, amount of Ni-zeolite are investigated on the oxidation of formaldehyde. Also using chronoamperometry technique, the catalytic rate constant (k) for oxidation of formaldehyde is found to be 7.56 × 104 cm3 mol−1 s−1.

Mesoporous and Al-rich MFI crystals assembled with aligned nanorods in the absence of organic templates

Mesoporous zeolites have been paid much attention recently due to their excellent mass transfer and high activity for bulky molecules as well as unique shape selectivity, but their syntheses usually require the presence of organic templates. Here, we report organotemplate-free synthesis of mesoporous and Al-rich MFI zeolite in the presence of the zeolite seeds (MFI-SDS). The MFI-SDS crystals are assembled with rod-like nanocrystals having almost the same aligned direction, confirmed by the sample transmission electron microscopy (TEM). The space between nanocrystals forms the mesoporosity in the sample, supported by N2 sorption isotherms. 27Al MAS NMR spectroscopy and ICP analysis show that the MFI-SDS has abundant tetrahedral Al species in the zeolite framework, giving the Si/Al ratio at 9.5. Catalytic tests in cumene cracking show that the MFI-SDS exhibits higher catalytic activities and longer catalyst life than conventional ZSM-5 zeolites synthesized in the absence (ZSM-5-OTF) or presence of organic template, TPA+ (ZSM-5-TPA). The excellent catalytic performance should be assigned to the combined contribution of the presence of both mesoporosity and rich tetrahedral Al species in the MFI-SDS. These features would be critically important for industrial applications of MFI zeolite catalysts in the future.

Effect of anion type on the synthesis of mesoporous nanostructured MgO, and its excellent adsorption capacity for the removal of toxic heavy metal ions from water

MgO nanostructures with controllable morphology and tunable textural properties synthesized via aqueous based route in the absence of organic templates were found to be excellent adsorbent for the removal of Pb(ii) and Cd(ii) ions from water.

Effects of Hydrothermal Duration on Synthesized Zeolite Rice Husk Particles

Zeolite particles were synthesized through in-situ extraction of silica from rice husk ash without seeding method in the absence of organic template by a static hydrothermal condition at various duration for 8, 12, and 24h. The effect amorphous silica content on hydrothermal duration of synthesis products was evaluated with X-ray diffraction (XRD), and field emission microscopy (FESEM). The present of zeolite Y without seeding method via XRD analysis show a mixture of zeolite A, Y and P. The transformation of amorphous rice husk particle was increased gradually with the increased of hydrothermal reaction. The FESEM images showed agglomerated cubic-shaped morphology of the powders with increase in crystallization reaction. .

Organic template-free synthesis of SAPO-34 molecular sieve membranes for CO2–CH4 separation

Continuous SAPO-34 molecular sieve membranes have been synthesized in the absence of organic templates used for CO2–CH4 separation.

The Characteristic of Synthesized Zeolite Rice Husk Particles via Different Routes

Zeolite particles were synthesized through in-situ extraction of silica from rice husk ash without seeding method in the absence of organic template by a static hydrothermal condition at 100oC/24h at varied ageing 8-24h. The effect of amorphous silica content on ageing time of synthesis products was evaluated with X-ray diffraction (XRD), Fourier transform infrared (FTIR) and field emission microscopy (FESEM). The present of zeolite Y without seeding method by XRD analysis show a mixture of zeolite A, Y and P. The transformation of amorphous rice husk particle gradually increased as early at 8 hours in ageing and increased with increase in ageing reaction. The vibration bands at around 974 cm-1 indicated Si-OH vibrations of the surface silanols, which is the characteristic of mesoporous silica. The FESEM images showed cubic-shaped morphology of the powders increased with increase in ageing reaction.

Template-free synthesis of beta zeolite membranes on porous α-Al₂O₃ supports.

The preferentially (h0l)-oriented beta zeolite membrane was prepared on the porous α-Al2O3 support by secondary growth of a beta seed layer in the absence of organic templates.

Organic template-free synthesis of ZSM-5 zeolite particles using rice husk ash as silica source

ZSM-5 zeolite particles were synthesized through in-situ extraction of silica from rice husk ash in the absence of organic template by a simple hydrothermal condition at 150°C/72–96h. The powders were characterized by XRD, TGA, DTA, FTIR, N2 physisorption studies, and field emission scanning electron microscopy (FESEM). Crystallization of ZSM-5 started at 150°C/72h. The vibration bands at around 540 and 1220cm−1 indicated the presence of characteristic double 5-ring of ZSM-5. The BET surface area and pore volume increased with increase in synthesis time from 72 to 96h at 150°C. FESEM images showed coffin-shaped morphology of ZSM-5 particles.

Synthesis and characterization of zeolite W and its ion-exchange properties to K+ in seawater

Zeolite W was synthesized by hydrothermal method using sodium aluminate and soluble glass as the raw materials in the absence of organic template. The ion-exchange equilibrium and ion-exchange capacity of the synthetic sample to K+ in seawater, as well as the selectivity coefficient to K+ in the mixed K+–Na+ solution were investigated. The sample was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersion spectroscopy (EDS) and Fourier transform infrared spectroscopy (FT-IR). Based on the ion-exchange equilibrium curve, it shows that the ion-exchange velocity of the sample to K+ is a rapid process and reaches leveling within 20min. The ion-exchange capacity of the sample to K+ is 54.9mg/g in seawater, and the selectivity coefficient to K+ is 85.6 in the mixed K+–Na+ solution. The sample has high selectivity to K+, and therefore it can be used to extract potassium selectively from seawater. The sample, which is mainly composed of Si, Al, K and O, exhibits a bouquet-like shape and is zeolite W verified by its XRD pattern.

Micron- and nanosized FAU-type zeolites from fly ash for antibacterial applications

The development of procedures for the synthesis of nanosized zeolites from cheap sources in the absence of organic templates is of great industrial importance. In this work, the size of FAU-type zeolites was decreased from micron- to nano-dimensions by reducing the amount of distilled water added to fly ash after alkali fusion. The fly ash zeolites showed high antimicrobial activity after introduction of Cu and Ag, which was associated with the release of Cu/Ag into the medium. This activity of Cu-containing zeolites from fly ash was similar to the activity of Cu-containing zeolites prepared by conventional methods but lower than that of Ag-containing zeolites.

Synthesis of mordenite zeolite in absence of organic template

Mordenite is a zeolite that has been used as a selective adsorbent and as a catalyst. Mordenite zeolite with crystal diameter 65nm and crystal length 7μm was successively synthesized in the absence of organic template by hydrothermal method at 180°C for 5days after stirring at high speed and aging in the synthesis mixture with the molar composition of 12Na2O:100SiO2:2Al2O3:500H2O. The produced samples were investigated using XRD, SEM, FT-IR, EDS, DTA/TG and BET surface area. The prepared sample, crystallized in needle shape crystals. Total (BET) surface area was 52.14m2/g whereas, total pore volume was 0.2cm3/g. Average pore diameter was 24.16Å. Thermogravimetry analysis (DTA/TG) showed that, at room temperature to 800°C, mordenite mass loss is 6%.