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In this study, metal–organic frameworks (MOFs) based on zirconium which are called MOF-808 were synthesized by solvothermal method. A series of Zr-MOF were synthesized at different temperatures and reaction times to find the best synthesis samples to produce dimethyl ether from dehydration of methanol. As synthesized MOFs were characterized with x-ray diffraction, standard electron microscopy, and BET, they showed high methanol conversion and selectivity for methanol oxidation. The relationship between crystallinity, reactivity and relation catalysts life was discussed. For the first time, this MOF was used as a solid catalyst in the conversion of methanol to dimethyl ether due to its thermal stability and moderate acidity. The results show that all samples had a crystalline structure and were properly synthesized. The performance of the synthesized catalysts, the selectivity, and the effect of reactor temperature in the conversion of methanol to dimethyl ether in a tubular reactor with weight hourly space velocity = 5 h−1 were investigated. The highest surface area is nearly 1360 m2/g, size dimension of samples is in the range of 200–800 nm, and the highest Langmuir surface area is 1530 m2/g. [ABSTRACT FROM AUTHOR]

Aromatic hydrocarbons are essential compounds, that the presence of which in fuels can improve the octane number. The conversion of the light alkanes to high value aromatics is vital from theoretical and industrial standpoints. Zeolites such as ZSM-5 play an essential role in the aromatization of light alkanes. This paper highlights the mechanism of aromatization of light alkanes such as methane, ethane, propane, butane, and its isomers. Furthermore, effective factors on the aromatization of light alkanes including metal type, crystallinity, acidity, space velocity, pretreatment of zeolites, co-feeding of light hydrocarbon, and operating factors such as temperature have been investigated to determine how a system of zeolite with metals can be useful to reach aromatization with high conversion. [ABSTRACT FROM AUTHOR]

Copper promoter has been added to HZSM-5 catalyst by ion exchange and impregnation methods in the methanol to gasoline (MTG) conversion process. Since the amount and the type of addition of the promoter influence the nanocatalyst performance, four nanocatalysts containing different types and amounts (0%, 1.9% with ion exchange, 1.9% with impregnation, and 7% with impregnation) of the added promoter prepared via one of the two addition methods have been compared. Among the nanocatalysts studied, although the catalyst promoted by the ion exchange method performs better (conversion: 100% and yield: 47.8%), it may have a lower catalyst life than that by impregnation (7%). [ABSTRACT FROM AUTHOR]

ZSM-5 nanoparticles are widely used as the catalyst in the methanol conversion to olefins (MTO) process due to their high surface area and short diffusion path length. However, agglomerate formation is a challenge for this catalyst. To address this issue, in this study, electrospinning was used for the first time to synthesize fibrous catalysts comprised of ZSM-5 nanoparticles embedded in the alumina nanofibers. The catalysts were characterized using XRD, FTIR, SEM, TEM, EDX-map, BET, and NH 3 -TPD analyses. In the synthesized samples, ZSM-5 nanoparticles with an average particle size of 683 nm are uniformly and homogeneously dispersed over alumina nanofibers with a 300 nm diameter. These composites form core-shell structures and have a reactor porosity of 0.85, which is higher than that of parent ZSM-5. In the MTO process, electrospun catalysts demonstrate superior catalytic activity and a longer lifespan than powder catalysts. 80 wt% ZSM-5- 20 wt% Al 2 O 3 with 47.76 % light olefin selectivity and complete methanol conversion after 321min on stream performed better than 50 wt% ZSM-5-50 wt% Al 2 O 3. Moreover, a lower coke formation of about 3.28 % was achieved for the 80 wt% ZSM-5- 20 wt% Al 2 O 3 sample. The reduced bulk density of the electrospun samples increases the probability of reactant and catalyst contact. Additionally, electrospinning is an effective method for reducing particle aggregation and improving catalytic process efficiency. [Display omitted] • Fibrous ZSM-Al 2 O 3 catalysts were synthesized by electrospinning for the first time. • Uniform distribution of ZSM-5 within Al 2 O 3 fiber decreased particle aggregation. • The lower bulk density of fiber catalysts facilitated reactant-catalyst contact. • Fibrous catalysts exhibited better performance in terms of activity and stability. [ABSTRACT FROM AUTHOR]

In this study, a well-designed hierarchical BiFeO 3 /ZIF-67 (BFO-ZIF) composite was successfully synthesized to improve the performance of photocatalytic hydrogen generation in comparison to bare BiFeO 3 and ZIF-67. Moreover, the behavior of the resultant electrocatalysts was also investigated in the hydrogen evolution reaction (HER). The synthesized electro-photocatalysts were characterized by various physical and photo/electrochemical analyses. The remarkable outcomes of the composite with 50 wt% of ZIF-67 in hydrogen generation correspond to the high specific surface area of the photocatalyst concurrently with the formation of active sites and new charge channels, leading to a modified charge transfer pathway and lower electron-hole recombination. The maximum H 2 generation rate over the optimal BFO-ZIF composite (BFO-ZIF(50)) attained 1617 μmol g−1 h−1 during visible light exposure, surpassing the rates observed for pure BFO and ZIF-67. Furthermore, the BFO-ZIF(50) electrocatalyst, with the onset potential of −0.089 V, resulted in an overpotential of −0.19 V at a current density of 10 mA cm−2, while a Tafel slope of 81.6 mV dec−1 in 1.0 M KOH showed the highest activity. The elevated photocatalytic hydrogen generation and improved HER performance of the developed catalysts signify a synergistic effect resulting from the junction and the Z-scheme charge transfer mechanism between the ZIF-67 and BFO nanomaterials. This introduces the BFO-ZIF composite as an efficient photocatalyst and electrocatalyst for hydrogen generation and evolution reaction. • Photocatalytic hydrogen generation and HER were studied by BiFeO 3 /ZIF-67 composites. • The maximum hydrogen generation rate of 1617 μmol g−1 h−1 is achieved. • The optimal electrocatalyst exhibited the overpotential of −0.19 V (10 mA cm−2). • High activity is attributed to the synergistic effect between the ZIF-67 and BiFeO 3. [ABSTRACT FROM AUTHOR]

In this study ZSM-5 Nano particles with high crystallinity were synthesized using a dry gel conversion technique. An L9 orthogonal array of the Taguchi method was applied to investigate the effect of synthesis parameters, such as crystallization time, gel drying temperature, molar composition of template (TPAOH) and water content in the crystallization stage on crystallinity and particle size of the ZSM-5 catalyst. The products were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Beside short crystallization time, the particle sizes were considerably smaller in comparison with those prepared using the hydrothermal method. The results showed that the particle size and crystallinity increased with increasing water content and crystallization time. The effects of gel drying temperature and molar composition of template were found to be more complex, however. Comparing to hydrothermal method, ZSM-5 samples synthesized with the dry gel conversion exhibited higher selectivity to gasoline than other hydrocarbons. [ABSTRACT FROM AUTHOR]

In this work, the effect of incorporating tungsten in HZSM-5 zeolites over the performance of desulfurization and octane enhancement processes of heavy naphtha was investigated. The physical and chemical characterization of the catalysts were analyzed by means of XRD, BET, NH 3 -TPD, TPR and XRF. The catalytic properties were determined at 5 barg, 450 °C, H 2 /Oil = 150 Nml/ml and WHSV = 1 h −1 inside a fixed bed reactor. The standard methods of detailed hydrocarbon analysis, gas chromatography, ASTM D-2699 and ASTM-D5453 were utilized to determine the liquid hydrocarbon compositions, detailed analyses of the off-gases, research octane number and the total amount of sulfur of the feed and products, respectively. The obtained results showed that the interaction between the Brönsted and Lewis acid sites for the W/HZSM-5 samples at low SiO 2 /Al 2 O 3 ratios and consequently high acidity in the specific operating condition led to the parallel aromatization-desulfurization reactions to proceed perfectly. The total amount of sulfur decreased by 71 wt% for the SiO 2 /Al 2 O 3 ratio of 20, and the aromatic component of the feed increased from 14.16 wt% to 72.82 wt% for the SiO 2 /Al 2 O 3 ratio of 40; hence, RON raised from 52 to 98. Overall, by comparing the performance of the catalysts, it can be concluded that the best performance of simultaneous octane enhancement-desulfurization process was observed for the catalyst No_3, in which the amount of sulfur compounds decreased by 67.5% and the octane increased by 90%. [ABSTRACT FROM AUTHOR]

First, the effects of ultrasound-related variables on the crystallinity and particle size of synthesised SAPO-34 catalysts were modelled using a genetic programming (GP) method. The results confirm that GP has good predictive power. Secondly, optimisation of the ultrasound parameters was considered using a genetic algorithm (GA) to obtain SAPO-34 catalysts with high crystallinity and minimum particle size for the best performance in the methanol to light olefins process. The GP models were used as the fitness functions inside the GA. Finally, the optimum solution was validated experimentally and the results indicate that there is a good agreement between experimental and predicted values. [ABSTRACT FROM AUTHOR]

The effect of incorporating nickel in HZSM-5 zeolite on its performance of desulfurization alongside octane enhancement processes of heavy straight-run naphtha was investigated for the first time. Experimental results indicated that the synergy between Brönsted and Lewis surface acid sites of Ni/HZSM-5 at a low SiO 2 /Al 2 O 3 ratio and consequently of high acidity made a great impact on the coupling aromatization and desulfurization reactions of heavy naphtha as a proper feed. After using a SiO 2 /Al 2 O 3 ratio of 60, the amount (wt%) of total sulfur decreased by 88%. In addition, the research octane number increased from 52 to 94 at the SiO 2 /Al 2 O 3 ratio of 40. [ABSTRACT FROM AUTHOR]

SAPO-34/AlMCM-41, as a new hierarchical nanocomposite was successfully synthesized via hydrothermal and dry-gel conversion. In an experimental and statistical study, effect of five input parameters including synthesis period, drying temperature, NaOH/Si, water/dried-gel and SAPO% were investigated on range-order degree of mesochannels and the relative crystallinity. X-ray diffraction (XRD) patterns were recorded to characterize the ordered AlMCM-41 and crystalline SAPO-34 structures. Nitrogen adsorption-desorption technique, scanning electron microscopy (SEM), field-emission SEM (FESEM) equipped with an energy-dispersive X-ray spectroscopy (EDS-Map) and transmission electron microscopy (TEM) were used to study the textural properties, morphology and surface elemental composition. Two reduced polynomials were fitted to the responses with good precision. Further, based on analysis of variances, SAPO% and time duration of dry-gel conversion were observed as the most effective parameters on the composite structure. The hierarchical porosity, narrow pore size distribution, high external surface area and large specific pore volume were of interesting characteristics for this novel nanocomposite. [ABSTRACT FROM AUTHOR]

ABSTRACT: This study includes three main parts: synthesizing the hierarchical silicoaluminophosphate (SAPO‐34) catalyst, evaluating the performance of this modified catalyst in the methanol to light olefins (MTO) process, and providing a new dynamic kinetic model for the modified catalyst. At first, a carbon nanotube (CNT) was used as a mesopore template in the sonochemical synthesis of SAPO‐34 hierarchical catalyst. By comparing the performance of this hierarchical catalyst and the common catalyst in the MTO process, it is observed that better performance is obtained on a modified catalysts for a longer period of time. Then, nine process tests were performed in differential fixed bed reactors at different temperatures and space velocities to obtain the kinetic model of the desired catalyst in the MTO process. Finally, the dynamic kinetic model of the modified SAPO‐34 catalyst was considered for main reactions in the MTO process. In this model, the rate equations were assumed elementary and lumped, and the decreasing of the catalyst activity over time on stream was also considered. The reactions constant and catalyst activity coefficient for different reactions were obtained by simultaneous connection of the code related to the reactor model and the genetic algorithm and genetic programming codes. The results obtained from the kinetic model were consistent with the experimental results. [ABSTRACT FROM AUTHOR]

SAPO-34 is highly selective and hydrothermally stable for MTO reactions but it is rapidly deactivated by the formation of coke through its micropores. The promising SAPO-34/ZSM-5 nanocomposite catalyst with a different ratio was synthesized by the ultrasonic-assisted hydrothermal method and it obtained products that were characterized to further investigate their catalytic performance. Utilization of the ultrasound method led to a faster synthesis time, a decrease of crystallite size, an increase of surface area, and a dominant mesopore structure. The physicochemical properties of the product were extensively investigated by XRD, FESEM, TEM, FT-IR, N2 adsorption-desorption techniques, and NH3-TPD. Results indicate that the composite had high conversion and selectivity compared to that of the original ZSM-5 and SAPO-34. When composite structures due to the synergic effect between ZSM-5 and SAPO-34 acted as promoted catalysts, they improved catalytic properties of composite catalysts. Moreover, the SAPO-34/ZSM-5 nanocomposite catalyst with 50% ratio synthesized by the ultrasonic-assisted hydrothermal method (U-S/Z (50%)) showed 100% conversion and 90% selectivity to light olefin at 450 °C. [ABSTRACT FROM AUTHOR]

Experimental parameters were optimized by the analysis of variance (ANOVA) by D-optimal experimental design using three levels of pressure, temperature, weight hourly space velocity (WHSV) and catalyst particle size. The effects of the above parameters on the gasoline selectivity in methanol to gasoline conversion (MTG) were studied. Given the effect of catalyst particle size on MTG process, three HZSM-5 catalysts with particle sizes of 90, 2000 and 4000 nm were synthesized and the effect of this important parameter was studied along with those of other parameters. Fischer test results showed that catalyst particle size and temperature are the most and least effective parameters, respectively, in the ranges studied. The most important two-way interaction variable was that of temperature and WHSV. The optimal conditions to achieve maximum gasoline selectivity in maximum conversion are pressure = 9.40 bar, temperature = 392 °C, WHSV = 1 h − 1 and particle size = 994 nm. In addition, by implementing industrial conditions in the equation proposed by the experimental design, the optimal catalyst particle size was found to lie in the 2500–3300 nm range. [ABSTRACT FROM AUTHOR]

SAPO-34 as a catalyst has high selectivity and hydrothermal stability, but it is rapidly deactivated by the formation of coke in its micropores. Evaluating the natural Clinoptilolite capability as a binder in nanocomposite catalysts is of interest because of its low cost, and accelerating the reaction. The SAPO-34/Clinoptilolite (S/C) nanocomposite catalysts were synthesized via ultrasonic-assisted hydrothermal method using Clinoptilolite as a binder. Subsequent performance of the catalyst was investigated in the methanol to olefins (MTO) reaction. The structures of synthesized nanocomposite were characterized with several methods such as XRD, XRF, FESEM, TEM, NH 3 -TPD, FT-IR, and nitrogen adsorption techniques. The modified Clinoptilolite was attained using nitric acid treatment. Although the physicochemical analysis indicated that HNO 3 -treatment decreases the crystallinity of the Clinoptilolite, the specific surface area of natural zeolite enhances considerably from 20.07 to 187.8 m 2 /g. The nanocomposite catalysts showed high selectivity toward light olefins with 100% conversion and 90% selectivity to light olefins as desired products at 450 °C. Nanocomposite with the additional diffusion paths for mass transfer provided by binder-filled space ascend to higher catalytic lifetimes in compare with free SAPO-34 catalyst. [ABSTRACT FROM AUTHOR]

A combination of carbon nanotubes (CNTs) and diethylamine (DEA) was used as a multitemplate in sonochemical synthesis of silicoaluminophosphate (SAPO)-34 hierarchical catalyst. The results show that such use of CNTs as mesopore template in sonochemical synthesis generates catalysts with hierarchical structure and remarkably different external surface area and particle morphology; on addition of CNTs, nanoparticles with spherical hierarchical are formed, having much larger external surface area compared with the common, cubic shape of SAPO-34 particles. Comparing the performance of the improved hierarchical nanocatalyst obtained using the CNT template with the base catalyst (without use of CNTs) in the methanol to light olefins (MTO) process, it was observed that the improved catalyst remained active for a longer time. Also, a larger amount of light olefins could be produced using this nanocatalyst compared with the base catalyst. Additionally, the effect of crystallization time and amount of DEA as a micropore template on the physicochemical features and performance of SAPO-34 crystals in the MTO process was evaluated. Very low amounts of DEA and short crystallization time resulted in very low crystallinity of the synthesized SAPO-34. However, large amount or long time resulted in synthesis of agglomerated, large SAPO-34 catalysts. Neither of these is desirable, and intermediate values were found to be favorable for catalyst synthesis. [ABSTRACT FROM AUTHOR]

Synthesis of AIPO-5 and SAPO-5 nanoparticles was followed by applying hydrothermal method to use them as adsorbents in the removal of Fe3+, Pb2+, and Cd2+ ions.The synthesized products were characterized using powder X-ray diffraction, scanning electron microscope (SEM), FTIR and BET analysis. The adsorption isotherms and kinetics including Langmuir, Freundlich, pseudo-first order, pseudo-second order and intraparticle diffusion models have been employed. The experimental adsorption equilibrium and kinetic data nearly followed the Langmuir isotherm and pseudo-second order kinetic model, respectively. It was found that the existence of the bridging hydroxyl group in the SAPO-5 structure causes chemisorption of Fe3+, Pb2+, and Cd2+ ions on SAPO-5 which have greatly improved the performance of this adsorbent against its low external surface area. Using AIPO-5 and SAPO-5 as novel adsorbents in heavy metal adsorption for the first time indicated the great potential of these adsorbents in removal of heavy metal ions from water. [ABSTRACT FROM AUTHOR]

The kinetics study of SAPO-34 crystallization from a gel containing morpholine as a structure directing agent (SDA) was investigated by means of X-ray diffraction (XRD) patterns in order to determine the kinetics parameters, i.e. induction times, rate constants, frequency factors, and activation energies for the induction and growth stages. The kinetics data of growth period were determined by using the Avrami–Erofeev nucleation growth model. SAPO-34 molecular sieves were synthesized by using both sonochemical-assisted hydrothermal and conventional hydrothermal heating at temperatures of 180, 200, and 220 °C to elucidate the influence of crystallization method on the crystallization kinetics of SAPO-34. The activation energy values indicated that the crystal growth mechanism was enhanced for samples synthesized sonochemically, whereas the induction energy was not greatly affected by using sonication process. Also, the kinetic compensation effect (KCE) was considered in order to obtain the isokinetic temperature. [ABSTRACT FROM AUTHOR]

In this study, the silicoaluminophosphate (SAPO) particles were synthesized based on dry gel conversion method using diethyl amine (DEA) as an organic structure directing agent (SDA). Transport pores were introduced into the crystalline structure of the catalyst using carbon nanotubes (CNT) as a hard template. The significance of molar ratio of CNT in the starting gel and the other synthesis parameters such as crystallization time, gel drying temperature and water content added in the crystallization stage, on crystallinity of SAPO-34, crystal phase, particle size and morphology were studied. The products were characterized by XRD, SEM, TEM, BET and EDX. D-optimal experimental design with four numeric factors including gel drying temperature, crystallization time, water/dry gel mass ratio and mole of CNT in the precursor gel each at three levels was implemented to optimize the experimental parameters by analysis of variance (ANOVA). The Fischer test results showed that, all the parameters have significant effect on the crystallinity of the synthesized samples. [ABSTRACT FROM AUTHOR]

In chemical reactions, a principal and influential parameter is particle size. The effect of HZSM-5 catalyst particle size on the kinetics of methanol conversion to gasoline has been investigated in this work. Three catalysts of 90 nm (Z1), 1 μm (Z2) and 4 μm (Z3) containing Si/Al ratios of 25, and a 90 nm sized with a Si/Al ratio of 50 (Z4) were prepared. The experiments were performed at temperatures of 598, 623 and 648 K at different feed rates. Chen and Schipper kinetic models, credible models for MTG process, were chosen to study the catalyst particle size effect on MTG process kinetics. R 2 adj. values for each of the models show that the experimental data are in relatively good agreement with Chen and Schipper models. In order to check the results of modeling with experimental data, objective function parameter was applied as a criterion and Z1 catalyst showed the best performance using Chen model, closely followed by Z2. [ABSTRACT FROM AUTHOR]

A D-optimal experimental design with three levels of SiO2/Al2O3, template/SiO2, H2O/SiO2, Na2O/SiO2 and TPABr/TPAOH ratio parameters has been used to optimize the experimental parameters by an analysis of variances (ANOVA). The effects of these ratios in the initial synthetic mixture on the size of the ZSM-5 zeolite nanoparticles have been studied. XRD and FE-SEM analyses were used to characterize synthetic samples. Fischer test results showed that H2O/SiO2 and TPABr/TPAOH ratios are the most and least effective parameters, respectively, in the range studied. The most important two-way interaction variables were the interaction of template/SiO2 and TPABr/TPAOH molar ratios. The average particle size was in the 34-79 nm range. Furthermore, a mathematical model for the synthesis of ZSM-5 zeolite nanoparticles was derived using experimental results. The optimized gel composition is as follows: SiO2/Al2O3=91.20, template/SiO2=0.16, H2O/SiO2=40.42, Na2O/SiO2=0.0147 and TPABr/TPAOH=0. [ABSTRACT FROM AUTHOR]

This study describes the effect of different composition ratios of nano ZSM-5 synthetic gel for obtaining ZSM-5 with higher crystallinty. The genetic-fuzzy approach is developed to estimate nano ZSM-5 crystallinity. The input variables of the proposed model are SiO 2 /Al 2 O 3 , template/SiO 2 , H 2 O/SiO 2 , SiO 2 /Na 2 O and TPABr/TPAOH ratio parameters and the output variable is the relative crystallinity. According to the results presented, the model developed can accurately predict the relative crystallinity with R 2 equal to 0.97. [ABSTRACT FROM AUTHOR]

The ZSM-5 catalyst has received significant attention in recent years due to its significant properties such as strong acidity and high surface area. Crystal size of the catalyst has been recognized as an important factor in its performance. This review investigates the effects of the crystal size of ZSM-5 on its catalytic performance—selectivity; conversion; lifetime, product distribution; and coke formation during methanol to hydrocarbons (MTH), methanol to dimethyl ether, ethanol to gasoline (ETG), ethylene to gasoline (ETG), acetone to gasoline (ATG), acetone to olefin (ATO), naphtha cracking, and and n-dodecane cracking processes. This study demonstrates that the reduction of crystal size leads to higher levels of activity, conversion, and stability in these various processes. [ABSTRACT FROM AUTHOR]

The catalytic performance of SAPO-34 catalysts which were synthesised hydrothermally under different conditions was investigated in methanol-to-olefins reactions. The significance of template, silicon sources and crystallisation time on catalytic performance, and deactivation of SAPO-34 catalysts, were studied. High methanol conversion and yield of light olefins were obtained over the nano-sized catalyst synthesised with tetraethylammonium hydroxide as template source and tetraethyl orthosilicate as silica source with a crystallisation time of 24 h, owing to its higher crystallinity and smaller crystal size. The SAPO-34 catalysts with larger sizes of crystals deactivate rapidly, while smaller crystals retain their activity for a longer time. [ABSTRACT FROM AUTHOR]

DFT calculations have been performed at the B3LYP/6-31++g** level to investigate the effect of the cluster size of ZSM-5 on the hydrogen atom of the Brönsted acid site via NQR and NMR parameters in methanol adsorption. ZSM-5 clusters have been modeled as 1T, 2T, 5T and 8T. T represents a general tetrahedral unit. Chemical shifts, δ, of H atom in the Brönsted acid site as well as quadrupole coupling constant, C, and asymmetry parameter, η, of H atom in the Brönsted acid site have been calculated. Spectrometric parameters showed that these parameters are influenced by the size and the shell of surrounding central T. Results indicate that inclusion of the next shell of T atoms (silicon atoms) around bridged hydroxyl group in the bare cluster models raises C and H δ from 1T to 5T, 2T to 8T, while no significant changes are observed in the same electronic environment. The calculated the natural charge distribution of hydrogen atom in the Brönsted acid site analyzed by the NBO method for comparison of the cluster models. [ABSTRACT FROM AUTHOR]

ZSM-5 nanoparticles of 50–100 nm size were synthesized by simultaneously adding tetrapropylammonium hydroxide and bromide using the following stoichiometry: NaAlO 2 : 25 SiO 2 : x TPAOH: y TPABr: 0.033 Na 2 O: 1000 H 2 O in which x + y is equal to 9. The synthesized samples were characterized by X-ray diffraction, field emission scanning electron microscope, transmission electron microscopy and Brunauer–Emmett–Teller surface area analysis. Impacts of various ratios of tetrapropylammonium hydroxide to tetrapropylammonium bromide, on size, crystallinity and surface were examined and it was found that in 6 tetrapropylammonium bromide to 3 tetrapropylammonium hydroxide mixed templates optimized ratio, the smallest size with the biggest surface and high crystallinity was achieved. Using tetrapropylammonium bromide template only for synthesis of ZSM-5 in high molar stoichiometry ratio (9 tetrapropylammonium bromide) in synthesis gel lead to get amorphous particles because of the synthesis gel sharp pH drop during crystallization. [ABSTRACT FROM AUTHOR]

ABSTRACT Density functional theory calculations have been performed at the B3LYP/6-31++G** level to investigate the effect of the isomorphously substituted ZSM-5 zeolite with trivalent elements B, Al, and Ga on the hydrogen atom of the Brönsted acid site via nuclear quadrupole resonance (NQR) and nuclear magnetic resonance (NMR) parameters. ZSM-5 clusters were modeled as ((H)3SiO)3-Si-O(H)-M-(OSi(H)3)3 (M = B, Al, and Ga). Variations of isotropic chemical shifts, δiso, of 1H atom in the Brönsted acid site as well as quadrupole coupling constant, CQ, and asymmetry parameter, ηQ, of 2H atom in the Brönsted acid site are well correlated with the trend in acidic strength of isomorphously substituted H-ZSM-5, estimated from the experimental results: B-ZSM-5 < Ga-ZSM-5 < Al-ZSM-5. The CQ value of 2H atom in the Brönsted acid site decreases in the order: B-ZSM-5, Ga-ZSM-5, Al-ZSM-5, respectively; eventually, their ηQ values of 2H atom in the Brönsted acid site increase concluding models with high CQ have a lower Brönsted acidity than those with low CQ. In addition, the calculated chemical shifts of the Brönsted proton increase in the sequence: B-ZSM-5 < Ga-ZSM-5 < Al-ZSM-5. All the results show a high consistency among NQR and NMR parameters and relative acidity of the isomorphously substituted ZSM-5 zeolite. © 2014 Curtin University of Technology and John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This review aims at investigating the effect of the different synthetic parameters on the crystallinity and crystal size of nanosized ZSM-5 zeolite. The influence of the different parameters, such as the material of the synthesis source, the material ratio to each other, crystallization time and temperature, aging time and temperature, microwave treatment, seeding, and sonication, on the size of the final product is studied and the reason for each phenomenon is explained. [ABSTRACT FROM AUTHOR]

D-optimal experimental design with three levels of SiO2/Al2O3, template/SiO2, H2O/SiO2, SiO2/Na2O and TPABr/TPAOH ratio parameters was used to optimize the experimental parameters by the analysis of variance (ANOVA). The effects of above mentioned ratios in the initial synthetic mixture on the crystallinity of the ZSM-5 zeolite were studied. The synthesized samples were characterized by XRD, FE-SEM, and TEM analysis. Fischer test results showed that SiO2/Al2O3 and H2O/SiO2 molar ratios are the most and least effective parameters, respectively, in the range studied. The most important two-way interaction variable was that of template/SiO2 and Na2O/SiO2 molar ratios. The optimum composition of the gel compound to achieve relative maximum crystallinity is SiO2/Al2O3 = 99.96, template/SiO2 = 0.16, H2O/SiO2 = 34.68, Na2O/SiO2 = 0.02 and TPABr/TPAOH = 1.44. [ABSTRACT FROM AUTHOR]

In this literature, it was successfully prepared metal-organic framework MIL-53(Al) for the first time at convenient conditions using sonication irradiation. Comparison of Sonochemical-assisted hydrothermal synthesis with conventional hydrothermal method had been investigated. Suitable morphology and unique porosity properties were obtained through Sonochemical-assisted approach, which has presented excellent features and good thermal stability for crystals samples with nano-sized particles versus the conventional hydrothermal method. Low reaction temperature of 150 °C and short time of synthesis 6 h investigated pure crystallinity of MIL-53(Al) via Sonochemical-assisted synthesis due to its ability to supply controlled amounts of energy to the solution that leads to increase nucleation rate and crystal growth. The characterization of samples was specified using X-ray diffraction (XRD), Scanning Electron Microscope (SEM), Fourier Transform Infrared Spectroscopy (FTIR), Nitrogen Adsorption Technique (BET) and Thermal Gravimetric Analysis (TGA). Highest surface area is nearly to 1363.5 m2/g, best thermal stability up to 600 °C, more uniform and narrower size distribution in the range of 0.7–0.93 μm at short sonication time 24 h and low temperature at 150 °C were observed. Sonochemical-assisted method is a rapid, green and effective approach under mild process conditions to produce MIL-53(Al) with desirable properties, uniform and small crystals size. [Display omitted] • MIL-53(Al) was synthesized via sonochemical-assisted approach. • Highest surface area was observed by using Nitrogen adsorption technique (BET). • Suitable morphology and unique properties were obtained under short irradiation time. • Ultrasound waves and low temperature were led to uniform and small crystal sizes. [ABSTRACT FROM AUTHOR]

Abstract: SAPO-34 nanocrystals with high crystallinity were synthesized by means of sonochemical method. An L9 orthogonal array of the Taguchi method was implemented to investigate the effects of sonication conditions on the preparation of SAPO-34 with respect to crystallinity of the final product phase. The experimental data establish the favorable phase crystallinity which is improved by increasing the ultrasonic power and the sonication temperature. In the case of ultrasonic irradiation time, however, an initial increases in crystallinity from 5min to 15min is followed by a decrease in crystallinity for longer sonication time. [Copyright &y& Elsevier]

Abstract: The sonochemical method was developed to synthesize uniform SAPO-34 (silicoaluminophosphate molecular sieve) nanoparticles with high crystallinity using TEAOH as a structure-directing agent (SDA). The physicochemical characteristics of SAPO-34 products, i.e. crystallinity, particle size and shape can be controlled by varying the ultrasonic-related variable such as ultrasound power intensity, ultrasonic irradiation time, sonication temperature and geometrical characteristics of the ultrasonic device (e.g., sonotrode size). The products were characterized by XRD, SEM, TEM and BET. It is found that each of the parameters can play a significant role in acoustic cavitation, number of nuclei and the crystal growth. The experimental data establish that the crystallinity is related to ultrasonic intensity and diameter of the sonotrode, as well as sonication temperature. By increasing the ultrasonic power, duration and the sonication temperature, the mean sizes of particles decrease and the morphology of the products efficiently alters from spherical aggregates of cube type SAPO-34 particles to uniform spherical nanoparticles. [Copyright &y& Elsevier]

Abstract: Methanol conversion to light olefins was investigated over sonochemically prepared SAPO-34 nanocatalyst (SONO-SAPO-34) with crystal sizes of about 50nm and its catalytic properties were compared with those of 600nm SAPO-34 catalyst synthesized hydrothermally (HT-SAPO-34). Both catalysts were used to elucidate the effect of crystallite size on their catalytic performance, especially in terms of life time. The product distribution over the two catalysts is almost the same, although their deactivation behaviors differ considerably. The HT-SAPO-34 catalyst with large crystals deactivates rapidly, while the SONO-SAPO-34 nanocatalyst retains its activity for a long time. This variation in catalytic deactivation according to the crystallite size of the SAPO-34 catalysts is attributed to the number of accessible cavities near their external surface and the diffusion limitation of the reactant and product molecules. [Copyright &y& Elsevier]

This paper reports the performance of a compost biofilter subjected to periodic intermittent loads of gas-phase hexane and toluene. The biofilter was operated for 10 h per day, at different empty bed residence times (4, 2 and 1.3 min), and at different inlet concentrations of hexane and toluene, varying between 2 and 3.8 g m-3, respectively. Steady-state removal efficiency profiles, reaching more than 90% for both the pollutants, was observed after 44 days of operation. Periodic operation of the compost biofilter was characterized by an adsorption step, followed by biological conversion of the pollutants by the microorganisms inherent to the compost. After resuming daily biofilter operation, the required times for biochemical reaction to dominate the initial adsorption step was observed to be 2.5 and 1 h, respectively, for toluene and hexane. The maximum elimination capacity due to the biological step was found to be 61.6 g m-3 h-1. The results from this study showed the effectiveness of the biofilter to handle mixtures of gas-phase pollutants, subjected to regular intermittent operations, thus proving their worthiness for industrial use. [ABSTRACT FROM AUTHOR]

Abstract: Microwave synthesis has been shown to dramatically enhance the reaction rate of many zeolite syntheses. In this study, crystals of nanosized SAPO-34 molecular sieves were synthesized by using microwave-assisted hydrothermal heating with different synthesis conditions to elucidate the effect of these contributing factors on the SAPO-34 formation, in terms of the size and morphology of crystals. All samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and thermal gravimetric analysis (TGA). It was found that microwave-assisted hydrothermal heating was required to obtain fully crystalline SAPO-34 crystals. The hydrothermal heating time played a crucial role in the shape and size control of nanosized SAPO-34 crystals, while the aging time had a negligible effect. The smaller pure SAPO-34 crystals were formed when using a higher concentrated solution as the initial gel. Smaller crystals were produced at higher microwave power, whereas the crystal morphology was found to be independent of the microwave power levels. The crystal size and morphology of SAPO-34 could be controlled by microwave irradiation time and an optimum microwave irradiation time for the preparation of nanosized SAPO-34 crystals was found. [Copyright &y& Elsevier]

Fungal biofiltration is an efficient way to treat hydrophobic compounds. Although temperature is a key factor in the biofiltration, the process modeling based on temperature effect in the kinetic parameters has been rarely considered due to its complexity. Therefore, in this contribution, a dynamics mathematical model which takes into account dispersion in gas phase, diffusion in biofilm, and temperature effect in the kinetic constants and other physical properties has been presented. The model was calibrated and validated by using previously reported experimental research in which the effect of temperature and intermittent and continuous loading on the biodegradation of n-hexane vapor had been investigated. The model prediction results revealed that a zero-order kinetic reaction fitted intermittent loading in the temperature range of 30–35 °C and continuous loading in the temperature range of 35–45 °C. Sensitivity analysis showed that at high inlet loads, approaching optimum bed temperature could change the rate limited biodegradation to a diffusion limited condition, and a part of the biofilm became inactive. [ABSTRACT FROM AUTHOR]

Silver ions can be reduced by 24 kHz ultrasonic waves in ion-exchanged Ag+–Y zeolite. In this research, silver ions were introduced into the nano-porous (1.2 nm) zeolite lattice by ion-exchange route. After the reduction process, silver nanoparticles were placed in the cavities, with a size of about 1 nm and also on the external surfaces of the zeolite, with sizes about less than 10 nm. Fast and simple lab-scale reduction of silver ions in the zeolite is important for researchers who work on catalytic properties of metallic silver–zeolite. Several reduction methods have been reported but reduction by ultrasonic waves is a new, simple, and size-controllable method with a high practical value which does not need any complicated facilities. In a sonochemical process, a huge density of energy is provided by the collapse of bubbles which formed by ultrasonic waves. The released energy causes the formation of reducing radicals that consequently reduce the silver ions. It is concluded that the higher silver content may result in the formation of larger silver crystals on the external surface of zeolite crystals. Also, the addition of 1-propanol and 2-propanol to the aqueous reaction medium does not cause better reduction. In addition, increasing the irradiation time and ultrasonic power does not affect the silver crystal growth significantly but the extent of silver ion reduction increases when the power of ultrasonic waves increases. All samples were irradiated under the same ultrasonic conditions. The samples were analyzed by XRD, EDS, SEM, and TEM. [ABSTRACT FROM AUTHOR]

MIL-101(Fe)-NH 2 was synthesized using solvothermal method to assess the selective adsorption of CO 2 over N 2 and CH 4. The BET surface area of adsorbent sample was 915 m2.g-1. The adsorption capacities of CO 2 , N 2 and CH 4 on MIL-101(Fe)-NH 2 at 4 MP and 298 K were achieved equal to 13, 3.8 and 5 mmol. g -1 respectively. Khan adsorption equilibrium model was applied to correlate the adsorption isotherms of pure gases. In addition to Khan model, the adsorption isotherm of CO 2 , which showed type II behavior, was also obtained by BET model as well as a newly presented hybrid model, which resulted in excellent agreement with the experimental data. Moreover, the selectivity of CO 2 over N 2 and CH 4 was estimated by Ideal Adsorbed Solution Theory (IAST). Comparison of the achieved results from IAST method with experimental data verified the accuracy of this method in the lower pressure. The selectivity coefficient was about 2.2 for CO 2 over N 2 and CH 4 at 16 bar. The achieved results from a classical micropore diffusion model showed that the diffusion coefficient of the pure gases was approximately constant with pressure. Moreover, the estimated values for diffusion time constants (D C /r C 2 × 103) for CO 2 , N 2 and CH 4 were obtained equal to 1.178, 1.118, and 0.802 respectively. The adsorption kinetic data were also correlated with empirical models. Ultimately, the results showed that pseudo-nth order empirical model achieved the best agreement with the experimental data, and it can be successfully applied for kinetic modeling of gas adsorption by MIL-101(Fe)-NH 2 MOF. Chemisorption of acidic carbon dioxide by basic NH 2 agent leads to type II behavior. [Display omitted] • MIL-101(Fe)-NH 2 , which uses nontoxic Fe3+ as the metal center, was synthesized by the solvothermal method. • The adsorption capacities of CO 2 , N 2 and CH 4 on MIL-101(Fe)-NH 2 were achieved equal to 13, 3.8 and 5 mmol. g -1. • A new hybrid model was presented to correlate precisely the equilibrium experimental data at high pressure. • Kinetic adsorption data were correlated with the nth order empirical model. [ABSTRACT FROM AUTHOR]

The aim of this study is to design a nonlinear model based on neural network for estimation of ZSM-5 particle size. The experimental data were gathered from the literature. The main preparation variables affecting ZSM-5 particle size are SiO 2 /Al 2 O 3 , template/SiO 2 , H 2 O/SiO 2 , and SiO 2 /Na 2 O ratios, crystallization time, and temperature, which are selected as input variables of the neural model. The results indicate that the designed model can exactly estimate the effects of six input parameters on the ZSM-5 particle size. An optimization paradigm based on genetic algorithm is employed to determine the minimum value of ZSM-5 particle size and the corresponding operating conditions. The optimized gel composition is as follows: SiO 2 /Al 2 O 3 =113.6, template/SiO 2 =0. 3 2, H 2 O/SiO 2 =42.10, SiO 2 /Na 2 O 73.21 and the optimal temperature and crystallization time are 443 K and 98 h, respectively. [ABSTRACT FROM AUTHOR]

• MLR, ANN and GP were used to model the performance of hierarchical SAPO-34 in MTO process. • The GP models had the highest accuracy for training and test data. • The optimal SAPO-34 catalyst was introduced using GA. • GP models were employed to calculate the evaluation function in the GA. • The GA results were in good agreement with the experimental results. The present study has focused on performance analysis of ultrasound-assisted synthesized nano-hierarchical silico-alumino-phosphate-34 (SAPO-34) catalyst during methanol-to-light-olefins (MTO) process. A classical method, i.e., multiple linear regression (MLR) and two intelligent methods, i.e., genetic programming (GP) and artificial neural networks (ANN) were used for modeling of the performance of nano-hierarchical SAPO-34 catalyst. We studied the influence of basic parameters for the sonochemical synthesis of nano-hierarchical SAPO-34 catalyst such as crystallization time, ultrasonic irradiation time, ultrasonic intensity, amount of organic template (diethylamine (DEA) and carbon nanotube (CNT)) on its performance (methanol conversion and light olefins selectivity) in MTO process. The results revealed that the models achieved using the GP method had the highest accuracy for training and test data. Therefore, GP models were used in the following to predict the effect of main parameters for the sonochemical synthesis of nano-hierarchical SAPO-34 catalyst. Finally, an optimal catalyst with the highest yield into light olefins was predicted using the genetic optimization algorithm. The genetic models were employed as an evaluation function in the genetic algorithm (GA). A good agreement between the outputs of GP models for the optimal catalyst and experimental results were obtained. The optimal ultrasound-assisted synthesized nano-hierarchical SAPO-34 was accompanied by light olefins selectivity of 77% and methanol conversion of 94% from the onset of the process after 9 h. [ABSTRACT FROM AUTHOR]

In this work, molecular dynamics (MD) simulation is used to study the adsorption of the anticancer drug, doxorubicin (DOX), on the wall or surface of pristine and functionalized carbon nanotubes (FCNTs) in an aqueous solution. Initially, the CNTs were functionalized by tryptophan (Trp) and folic acid (FA), and then the DOX molecules were added to the system. The simulation results showed that the drug molecules can intensely interact with the FCNTs at physiological pH. Furthermore, it was found that as a result of functionalization, the solubility of FCNTs in an aqueous solution increases significantly. The effect of pH variation on drug release from both pristine and FCNTs was also investigated. The obtained results indicated that in acidic environments due to protonation of functional groups (Trp) and as a result of repulsive interaction between the DOX molecule and functional groups, the release of DOX molecules from FCNT's surface is facilitated. The drug release is also strongly dependent on the pH and protonated state of DOX and FCNT. [ABSTRACT FROM AUTHOR]

Methanol-to-olefin conversion is one of the most successful approaches to producing light olefins. It has been proved that SAPO-34 is the best catalyst for this process. This molecular-sieve is characterized by high thermal stability, moderate acid sites, and shape selectivity. In this report, SAPO-34 was synthesized using the seed-assisted method. Effects of OSDA and seed on crystallinity and particle size were investigated using Central Composite Design. Samples were characterized by XRD, FE-SEM, FTIR, BET, EDX, and TPD. Results showed that the samples had excellent physicochemical properties. The design of Experiments could predict the results accurately (R2 > 0.9). It was demonstrated that template was the key factor in the seed-assisted synthesis of SAPO-34. Template consumption was reduced by 50%, and it was proved that the synthesis time could be effectively decreased to 3 h due to rapid nucleation. Samples exhibited 100% methanol conversion and up to 90% selectivity toward ethylene and propylene. [Display omitted] • High satisfactory R2 for optimizing the OSDA and seed content in seed-assisted method. • Excellent physicochemical properties, with tunable morphology and acidic properties. • A green synthesis route with 50% reduced template consumption and 88% energy saving. • Outstanding MTO performances with up to 90% light olefin selectivity. [ABSTRACT FROM AUTHOR]

In an experimental and statistical study, the effects of five synthesis parameters on the degree of order of nano‐sized Al‐MCM‐41 were basically investigated. In a series of designed experiments, hydrothermal conditions (temperature and time), Si/Al, NaOH/Si, and cetyltrimethylammonium bromide/Si molar ratios were studied each at three levels. Degree of order of mesoporous channels was evaluated using small angle XRD. Nitrogen adsorption‐desorption technique, scanning and transmission electron microscopy (SEM‐TEM), and field‐emission SEM were also applied to detect the textural properties and the morphology of prepared nanoparticles. Energy‐dispersive X‐ray spectroscopy and mapping (EDS‐Map), inductively coupled plasma‐optical emission spectroscopy, and small angle X‐ray scattering were provided as complementary analyses. An accurate reduced quadratic equation was proposed as a function of effective terms in good agreement with the experimental results. Based on the analysis of variance, the amount of aluminum incorporated, sodium hydroxide, and the hydrothermal treatment duration was found to possess more dramatic effects on the degree of order than the other factors. The optimum conditions for the synthesis of a well‐ordered Al‐MCM‐41 were also obtained with the lowest template and the minimum hydrothermal duration verified by two validation tests. [ABSTRACT FROM AUTHOR]

Photoelectrocatalytic pollutant degradation is one of the most promising advanced oxidation processes for wastewater treatment. However, its efficiency dramatically depends on the development of photoelectrocatalyst materials. Therefore, here, ternary Ti 0.2 -V x -Bi (0.8−x) -oxides (x = 0.15, 0.3, 0.4, 0.5, and 0.65) were applied as the photoelectrocatalysts for pollutant degradation. The photoelectrocatalysts were synthesized by a dip-coating thermal decomposition (DCTD) method. The physical and optical characteristics of photoelectrocatalysts were analyzed by XRD, FE-SEM, EDS, PL, and DRS tests. The photo/electrochemical behavior of samples was studied by LSV, EIS, and chronoamperometry with and without visible light illumination. The activity of samples was investigated by photocatalytic, electrocatalytic, and photoelectrocatalytic treatment of methyl orange and rifampin solutions under visible light irradiation. The kinetics of photocatalytic, electrocatalytic, and photoelectrocatalytic degradation processes was investigated by the Langmuir-Hinshelwood (L-H) kinetic model. Moreover, the mineralization extent of rifampin was studied by COD test. The results pointed to the optimum composition of ternary Ti 0.2 V 0.4 Bi 0.4 -oxide, in terms of both photocurrent and degradation time, which could completely degrade methyl orange and rifampin solutions in less than 15 min at a current density of 5 mA/cm2 under visible light irradiation. The superior performance of Ti 0.2 V 0.4 Bi 0.4 -oxide was attributed to its smaller particle size (larger surface area), lower band gap (2.1 eV), the lower recombination rate of e-/h+ pairs, and lower charge transfer resistance than the other compositions. The high activity and stability of Ti 0.2 V 0.4 Bi 0.4 -oxide introduce it as an efficient photoelectrocatalyst for pollutant degradation by the advanced oxidation process (AOP). • Ternary Ti-V-Bi oxides were developed to proceed in a photoelectrocatalytic AOP. • A tuned band gap of 2.1 eV was measured for the Ti 0.2 V 0.4 Bi 0.4 -oxide electrocatalyst. • Less than 15 min was enough to degrade MO and rifampin solutions completely. • The (L-H) kinetic model investigated the kinetics of degradation processes. [ABSTRACT FROM AUTHOR]

Synthesis of nano SAPO-34 has attracted a considerable attention in recent years. The quality of catalytic performance of SAPO-34 is improved at nanoscale especially in the methanol to olefins (MTO) process. Due to higher surface area and smaller diffusion length, nano size SAPO-34 shows a longer life time in MTO reaction. This review investigates different routes for nano SAPO-34 synthesis. Also it investigates various effective factors such as crystallization time and temperature, type and concentration of template, water content, microwave and ultrasound power and irradiation time, which influence the final obtained SAPO-34 characteristics. [ABSTRACT FROM AUTHOR]

An experimental investigation of the SO2 removal reaction by pure CuO was performed by thermogravimetry. In addition, mathematical modelling of this non-catalytic gas-solid reaction was performed using the random pore model. Modelling predictions of CuO conversion-time profiles at various temperatures and SO2 partial pressures compared well with the experimental results. The inherent rate constants and the product layer diffusivities were estimated between 400 and 600 °C. [ABSTRACT FROM AUTHOR]

The crystallisation of the MeAPSO-34 material was studied under dry-gel conversion conditions and using two and three templates. This study has been focused on the effect of the incorporation of a mixture of Ni and Mn into the SAPO-34 framework. The MeSAPO-34 samples were characterised by X-ray diffraction, energy-dispersive X-ray spectrometer, scanning electron microscope, temperature-programmed desorption and Brunner–Emmett–Teller. The influence of metal incorporation into the framework of SAPO-34 (MeAPSO-34) on methanol conversion was investigated in this study. The performances on methanol conversion for these catalysts were different according to the properties of metals incorporated into the SAPO-34 structure. The catalytic performance demonstrated high activity and light olefins selectivity for the prepared catalysts. Among the light olefin products, Mn and Ni incorporation is helpful for propylene generation, but samples with a mixture of Ni and Mn favour the ethylene production. [ABSTRACT FROM AUTHOR]

The influence of using two, three and four templates on the catalytic performance of SAPO-34 catalyst during the methanol-to-olefins (MTO) reaction has been studied. SAPO-34 catalysts were prepared hydrothermally by applying various combinations of four organic templates (TEAOH, morpholine, DEA and TEA). The results showed that applying a combination of templates affects the activity and selectivity of samples by prolonging their life time. Comparing with a sample prepared by a single template, using more than one template enhances the methanol conversion and selectively of light olefins. Apart from the effect of the number of templates on the performance of these catalysts, acidity also plays a significant role. It was found that catalysts synthesised by two and four templates give better performance due to their mild acidity, smaller particle size and higher BET surface area. [ABSTRACT FROM AUTHOR]

In this work, the experimental investigationof SO2removalreaction by CuO was accomplished in a packed bed reactor between 400and 600 °C at 1250–5000 ppm of inlet SO2. Moreover,the mathematical modeling of this reaction was performed by the randompore model. The partial differential equations in a packed bed reactorwere solved using finite element technique. The kinetic parameterswere previously determined from thermogravimetry tests on a single-pelletCuO reaction with SO2at various concentrations and temperatures.The results of modeling consist of packed bed breakthrough curvesat different temperatures and SO2concentrations, whichwere compared with the experimental results successfully. By increasingthe reactor temperature from 400 to 600 °C, the appearance ofthe breakthrough curve shifts from 200 to 550 min. Similarly, by decreasingthe inlet SO2concentration from 5000 to 1250 ppm, thebreakthrough profile appears at 900 min instead of 200 min. [ABSTRACT FROM AUTHOR]

[Display omitted] • Synthesis of ZSM-5/ZSM-12 nanocomposites by hydrothermal and sonochemical methods. • Increasing crystallinity and ZSM-5 phase by raising Si/Al in hydrothermal samples. • Reducing crystallization time using the sonochemical synthesis method. • Increasing crystallinity, surface area, and ZSM-12 phase using ultrasonic waves. • Higher selectivity of olefins with more C 3 =/C 2 = ratio in the sonochemical sample. The use of ultrasonic waves was developed for synthesis of zeolites at shorter crystallization time with improving their desirable properties. A series of nanostructured ZSM-5/ZSM-12 composite zeolites with different Si/Al ratios and alkalinity using organic templates were prepared by hydrothermal and sonochemical synthesis methods. The physicochemical properties of synthesized nanocatalysts such as structure, morphology, textural, and acidity were characterized via XRD, FESEM, N 2 physisorption, FTIR, TPD-NH 3 , TGA-DTG techniques. The results revealed that increasing the Si/Al ratio and alkalinity in the hydrothermal samples enhanced the crystallization, formation of amorphous microcrystals, and dominant phase of MFI with decreasing MTW competitive phase. Zeolites synthesized by high-temperature and short-time sonochemical method had higher crystallinity, less dominant phase of ZSM-5, smaller crystals, greater surface areas, higher concentration of Brønsted acid sites, and stronger strength of moderate/strong acid sites. The catalytic performance of the zeolites for MTH conversion was evaluated under a reaction temperature of 450 °C at different times on stream. The results showed that the sonochemical zeolite had a higher methanol conversion (100%), higher selectivity toward olefins (28% vs. 19%) with more C 3 =/C 2 = ratio (0.79 vs. 0.58), and lower alkanes selectivity (66% vs. 72%) after 240 min TOS. [ABSTRACT FROM AUTHOR]