The aim of this paper is to modify the X zeolite adsorbent to enhance nitrogen adsorption capacity. To this end, a novel procedure for modification of X zeolite, including both NH4+ treatment and Ca2+ ion-exchange, is introduced which results in a hierarchical mesopore-micropore structure with multilayer N2 adsorption behavior. The presented adsorbents, “hierarchical X zeolite” (HX) and “Ca2+ exchanged hierarchical X zeolite” (CaHX), are compared with the available microporous 13X zeolites, modified by Na+ (NaX), and mixed Ca2+ /Na+ cations (CaNaX). The properties of these adsorbents are characterized by N2 adsorption-desorption in 77K, XRD, and XRF analysis. The high-pressure N2 adsorption isotherms are measured at 283, 298, and 31

The aim of this work is sorptive removal of cesium and strontium ions from aqueous solution using natural zeolite and management of produced secondary waste. Characterization of the natural zeolite was performed by X-ray diffraction (XRD), X-ray fluorescence (XRF), Brunauer–Emmett–Teller (BET), and field emission scanning electron microscopy (FE-SEM). The effective parameters on the sorption process such as initial solution pH, adsorbent dosage, and concentration of cesium and strontium ions were optimized by using experimental design method. Based on the results, removal efficiency for cesium ion was about 67.8% at the optimum condition of adsorbent dosage of 0.40 g, pH= 7.23 and Cs+ concentration of 10 mg L− 1, and for the strontium

A method based on diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) was employed to quantify the mesopore volume of the ZSM-48 zeolites. Partial least squares (PLS) and support vector machine (SVM) multivariate calibration methods were used to construct linear and non-linear regression models, respectively. N2 physisorption analysis using BET model was used as a reference method to determine the mesopore volume of zeolites. In mid-IR region, three different ranges, 3700–3800, 3200-3800 and 400-4000 cm-1 were investigated in order to selection the optimum spectral range for evaluation of the mesopore volume of the zeolites. The effect of orthogonal signal correction (OSC) as a preprocessing method on the quality of linea

Vanadium oxide supported on TiO2(P25) catalysts were synthesized via atomic layer deposition (ALD) of vanadyl acetylacetonate (VO(acac)2). Comprehensive investigations were performed to evaluate the ALD temperature window and the saturation deposition period of VO(acac)2, which were found to be 140–210??C and 120?min, respectively. The synthesized catalysts were compared to their corresponding impregnation ones for the oxidative dehydrogenation of propane reaction (ODH-P). The ODH-P results indicated the superior performance of the ALD catalysts for the low temperature ODH-P (< 350??C) given its better dispersion of vanadium oxide(vanadia) in the ALD catalysts. Several characterization techniques including HR-TEM, FE-SEM, XRD, BET, XPS

Separation of carbon dioxide in flue gases from the combustion equipment is one of the most serious concerns for industries and especially for the power plants which are the main producers of this pollutant gas. From the various separation methods, vacuum pressure swing adsorption (VPSA) process is attracted interest due to its lower energy consumption and high efficiency. A VPSA process was studied for the separation of a mixture of CO 2/N 2 (80% N 2 and 20% CO 2). Experiments were performed in an eight-step, four-bed setup using zeolite 13X and carbon molecular sieve (CMS) as adsorbents. Experimental measurements by the bench-scale system have been obtained in a pressure range of 2.7–4.7 bar, cycle times of 360–600 s, the product flow

Abstract Two types of zirconium-containing hierarchical SAPO-34 catalysts were successfully synthesized by isomorphous substitution and impregnation methods and applied for the conversion of methanol to light olefins. Carbon nanotube was employed as a mesopore template to create mesopores in the crystals of SAPO-34. Physical and chemical characterizations of the catalysts demonstrated that the modification of SAPO-34 with Zr by isomorphous substitution and impregnation methods gives rise to differences in acidity, porosity and crystal size. MTO results showed that the lifetime of the catalysts was in the order of ZrAPSO-34 > SAPO-34 > Zr/SAPO-34 while the selectivity to ethylene was in the order of Zr/SAPO-34 > ZrAPSO-34 > SAPO-34.

In regards to the unique properties of lithium, lithium separation with high purity is crucial in various industries. Due to the close radii of alkali and alkaline earth metals, this is important to choose a technique with appropriate properties for ion separation in aqueous medium. Among the available methods for lithium enrichment, polymer inclusion membrane (PIM) system has features that meet the needs. In this study, a PIM containing green polyol as the base polymer, 12-Crown-4 (12C4) as the carrier and 1-butyl-3-methylimidazolium chloride (BMIMCl) ionic liquid was synthesized to separate lithium ion from an aqueous solution of Li+, Na+, K+, Ca2+, and Mg2+. Also, the zeolitic imidazolate framework type ZIF-8 was employed in the membrane

SAPO-34 samples were prepared via a seeding-induced method with a considerable reduction of template concentration. The resultant SAPO-34 zeolites were investigated by XRD, FESEM, EDS, N2 adsorption, and NH3-TPD analyses. The samples represent different catalytic activity in the MTO process due to their differences in the physic-chemical properties, including crystallite/particle sizes, surface area, acid strength and concentration. Pure SAPO-34 was obtained with a 60% reduction of organic template for the first time. However, due to the increase of particle sizes, it did not show the desired catalytic performance. An excellent catalytic performance was achieved for the seeding-induced catalyst prepared by a 40% reduction of template conten

This study modelled and optimized the oxidative desulfurization of gas condensate with ozone, as a gaseous oxidant. Experiments in this study were non-catalytic, and sulfone extraction was done by acetone. Response surface methodology was applied for the experimental design, mathematical modeling, and optimization using Design-Expert? software. The influence of effective variables and their interaction on the response was also investigated. For the first time, non-catalytic ozonation of this feed was performed on the oxidative desulfurization process. The developed model properly fitted the experimental results. The accuracy of the model was confirmed, while this model predicted 95% desulfurization would result in the optimized conditions,

SAPO-34 catalysts were synthesized through the seeding approach under different seed conditions. The different seed synthesis times (6 h, 12 h, and 24 h) and three types of seeds were evaluated: the dried seed, the calcined seed, and the mother liquor from an unseeded synthesis, called the solution seed. Pure SAPO-34 was obtained using 12 h and 24 h solution seeds, in which a 40% reduction of template consumption was achieved simultaneously. All seeding induced samples represented higher catalytic performance in the MTO process than conventional SAPO-34 due to the smaller crystallite/particle sizes and larger external surface areas and mesopore volume. Furthermore, the changes in the acidity of samples affect their performance. The maximum

The SAPO-34 catalysts were successfully synthesized with different amounts of a cheap and green nonionic surfactant (Triton X-100) as a mesoporogen additive and MOR/TEAOH as microporous mixed templates. The prepared samples were characterized and tested in the methanol to olefins (MTO) reaction under the industrial feed composition of 72 wt% methanol in water. The results revealed that the surfactant concentration affects the acidity, particle size, and textural properties which results in different catalytic performances. The sample prepared with the surfactant molar ratio of 0.02 exhibits a 12% improvement in the light olefins selectivity (90%) as well as the longer catalyst lifetime (more than 330 min) compared to the parent one (79

High-end applications require a very tall vertical extraction column in some cases which deteriorates protection against radiation and cannot be employed for indoor applications. On the other hand, horizontal extraction columns offer higher efficiency and pretension, but lower maximum throughput. In order to address this issue, the L-shaped pulsed extraction column is a new type of extractors which were recently introduced for such applications with area constraints. The objective of this study is to evaluate the effects of operating parameters and physical properties on the variation of holdup and slip velocity in this type of extractors for three liquid systems including toluene–water, butyl acetate–water and n butanol–water without

Three Beta catalyst samples using carbon nanotubes (Beta/CNT), carbon nanofiber (Beta/CNF) and graphene oxide (Beta/GO) templates and one sample in the absence of nanostructured carbon templates have been successfully prepared to investigate the impact of carbon nanostructures as hard templates. Tetraethylammonium hydroxide has been applied as the template in each of the samples. XRD, FESEM, BET, FTIR and NH3-TPD analyses were used to study the effect of each of the hard templates on the physicochemical properties of the synthetic samples. In addition, the catalytic activity of the catalysts prepared was compared in the methanol to olefin conversion (MTO) reaction at atmospheric pressure, temperature of 400 ?C and WHSV of 8.0 h−1. Varia

Mesoporous ZSM-48 zeolite was prepared by alkaline desilication at optimized conditions using central composite design (CCD) under response surface methodology (RSM). Statistical models were designed to predict high BET surface area, high mesopore volume and specified mean pore diameter. The desilication temperature and NaOH solution concentration were varied in the ranges 0.1-0.3 M and 60-80 ?C respectively. It was found that the NaOH concentration was more effective factor than temperature for mesoporosity development in ZSM-48 zeolite. Variance analysis showed that CCD equations were significant for the desilication parameters (R2=0.98 for mesopore volume, R2=0.95 for BET surface area and R2=0.98 for mean pore diameter). The influence

In order to study the effect of carbon nanostructures as hard templates, three silicoaluminophosphate samples using carbon nanotubes (SAPO-34/CNT), carbon nanofiber (SAPO-34/CNF) and graphene oxide (SAPO-34/GO) as well as one sample in the absence of nanocarbon structures were successfully synthesized. The effect of each of the hard templates on the physicochemical properties of the synthetic samples was studied using XRD, FESEM, BET, FTIR and NH3-TPD analyses. Furthermore, the catalytic activity of the synthetic catalysts was compared in the methanol to olefin conversion (MTO) at atmospheric pressure, temperature of 400 ?C and WHSV of 4.0 h−1. The results of the investigation of physical characteristics of the catalysts indicate that

Heavy fuel oils usually have high sulfur content and most of the sulfur compounds have bulky thiophenic structures which resist desulfurization. Oxidation of these sulfur compounds to sulfones weakens the C–S bonds and sulfur can be removed as SO 2 by thermolysis. This study investigated oxidative desulfurization of heavy vacuum gas oil (2.81 wt% S). Oxidation was achieved with hydrogen peroxide and formic acid. Then, the oxidized feed underwent thermolysis at 355-410 C for 0.5-3 h to identify the maximum desulfurization with minimum feed conversion to light products. The effects of parameters such as time and temperature were studied. Temperature had significant effects in comparison to other parameters. Desulfurization of 65% with 6 wt%

Three ZSM-5 catalyst samples synthesized using carbon nanotubes (ZSM-5/CNT), carbon nanofiber (ZSM-5/CNF) and graphene oxide (ZSM-5/GO) templates as well as one sample containing no template have been studied to study the effect of carbon nanostructured hard templates. The template in each sample was tetrapropylammonium hydroxide. The impact of each of the hard templates on the physicochemical properties of the synthetic samples was investigated via XRD, FESEM, BET, NH 3-TPD and FTIR analyses. Moreover, the catalytic activity of the catalysts synthesized was compared in the methanol to olefin conversion (MTO) reaction at atmospheric pressure, temperature of 450 C and WHSV of 8.0 h− 1. Considering the results of the investigation of the ph

In this study, sonochemical synthesis was used to prepare nanostructured HZSM-5 catalysts. The three most effective ultrasound related variables including ultrasound power, irradiation time, and sonication temperature were investigated. The combined effect of these variables on relative crystallinity and mean crystal size of HZSM-5 nanocatalysts was studied using a central composite design. Higher crystallinity and lower crystal size were obtained by increasing ultrasound power, irradiation time, and sonication temperature while there was an optimum range for mentioned variables. The maximum relative crystallinity and minimum mean crystal size were obtained as 55.51% and 62.37 nm, respectively, under the optimal conditions of ultrasound pow

Nanostructured HZSM-5 catalysts were synthesized using sonochemical and hydrothermal techniques. The central composite experimental design method was applied to investigate the effects of three critical preparation variables including ultrasound power, irradiation time, and sonication temperature on the structure of the prepared catalysts. The catalysts were characterized by XRD and FE-SEM techniques. The catalytic performance of the selected catalysts was also evaluated in methanol conversion to propylene reaction. The results showed that higher crystallinity and lower particle size were obtained by increasing the above-mentioned factors. The maximum relative crystallinity and minimum mean particle size were obtained as 55.5% and 62.4 nm

In this study, hybrids of nanoporous MIL-101(Cr) and MIL-53(Al) were synthesized using a hydrothermal method for various time periods, ranging from 8 to 40 h. The prepared materials were characterized by powder X-ray diffraction (PXRD) and elemental analysis, and their specific surface areas were measured by N2 sorption at 77 K using the Brunauer–Emmett–Teller (BET) method. To investigate the practical application of these materials, the pure carbon dioxide and methane adsorption capacities of the samples were determined using the volumetric method. The Langmuir model was used to fit the CO2 and CH4 isotherms. Extended Langmuir (EL) equations and the ideal adsorbed solution theory (IAST) models were used to obtain the CO2/CH4 selectivit