Sharif Digital Repository

A novel mesoporous silica-functionalized dual Brønsted acidic species has been introduced as an efficient catalyst for solvent-free esterification of fatty acids with ethanol. The structure of the catalyst has been characterized by FT-IR spectroscopy, thermal gravimetric analysis (TGA), TEM and N2 adsorption-desorption. TGA of catalyst 1 showed no weight loss before 200 °C, indicating a high degree of hydrophobicity of the surface of the mesoporous silica. TEM images and nitrogen adsorption-desorption showed no noticeable changes to the structure of the catalyst before and after acid treatment. pH metric analysis was performed for the catalyst to determine the loading of the acidic sites.... 

Coke deposition mechanism on a commercial Pt-Re/γ-Al 2O3 naphtha reforming catalyst was studied. A used catalyst that was in industrial reforming operation for 28 months, as well as the fresh catalyst of the unit were characterized using XRD, XRF, and nitrogen adsorption/desorption analyses. Carbon and sulfur contents of the fresh and the used catalysts were determined using Leco combustion analyzer. The pore size distributions (PSD) of the fresh and the used reforming catalysts were determined using BJH and Comparison Plot methods. The Comparison Plot method produced the most reasonable PSDs for the catalysts. Through comparison of the PSDs of the fresh and the used catalysts, it was... 

In this paper, the pyrrolic nitrogen functional group's presence is investigated in the selective adsorption of CO2. The grand canonical Monte Carlo (GCMC), molecular dynamics (MD), and density functional theory (DFT) were used for this study's goal. GCMC was used to calculate adsorption isotherms, selectivity, and isosteric heats. MD was used to calculate the radial distribution function (RDF) and diffusion. Reactivity parameters, electrostatic potential (ESP), reduced density gradient (RDG), and independent gradient model (IGM) were calculated using DFT. Adsorption isotherms, selectivity, and isosteric heats demonstrated that the NH group caused the selective adsorption of CO2 among CH4,... 

GAC has been modified by loading of potassium nickel hexacyanoferrate (KNiCF) as a new adsorbent for cesium adsorption. The potassium nickel hexacyanoferrate-loaded granular activated carbon (KNiCF-GAC) was characterized using powder x-ray diffraction (XRD) and nitrogen adsorption-desorption isotherm data, infrared spectroscopy, and its cesium adsorption performance in aqueous solution was investigated. The effect of the various parameters such as initial pH value of the solution, contact time, temperature, and initial concentration of the cesium ion on the adsorption efficiencies of KNiCF-GAC have been studied systematically by batch experiments. The adsorption isotherm of KNiCF-GAC was... 

The preparation, characterization and catalytic application of a novel copper-loaded ionic liquid-based periodic mesoporous organosilica (Cu@PMO-IL) are described. The mesoporous structure of the Cu@PMO-IL material is characterized by transmission electron microscopy (TEM) and nitrogen adsorption-desorption analysis. The thermal stability of the material is also determined by thermal gravimetric analysis (TGA). The presence of copper species in the material framework is confirmed by X-ray photoelectron spectroscopy (XPS) and elemental analysis (EA). The catalytic application of Cu@PMO-IL nanocatalyst is then investigated in the Biginelli condensation of different aldehydes with urea and... 

Ultra fine CuO nanoparticles In the range of 2 ± 0.2 nm were synthesized by the supercritical hiydrotliermal method in a batch reactor. Itwas demonstrated that elevating the pH of the Cu2+ precursor solution to around 6 (neutral condition) not only does not lead to excessive agglomeration of the particles, but also reduces particle size and in general promotes their nanoscale characteristics. Prepared nanoparticles were immobilized in the biopolymcric matrix of barium alginate and calcined at different temperatures resulting in micro spherical granules of high porosity and elevated mechanical strength. The fabricated samples were characterized using x-ray diffractometry (XRD), transmission... 

The Zr-based metal-organic framework (MOF, UiO-66) was synthesized solvothermally. The synthesized UiO-66 was activated using different solvents (acetone, chloroform, and ethanol) via two activation methods of centrifugation and Soxhlet extraction over different periods (1–10 days). The crystalline structure and morphology of the synthesized UiO-66s were characterized by X-ray diffraction (XRD), nitrogen adsorption-desorption, and field-emission scanning electron microscopy (FESEM) techniques. The adsorption behaviors of the synthesized UiO-66s were then investigated by selecting anionic methyl red (MR) and cationic methylene blue (MB) as the model dyes. It was found that a change in... 

The Zr-based metal-organic framework (MOF, UiO-66) was synthesized solvothermally. The synthesized UiO-66 was activated using different solvents (acetone, chloroform, and ethanol) via two activation methods of centrifugation and Soxhlet extraction over different periods (1–10 days). The crystalline structure and morphology of the synthesized UiO-66s were characterized by X-ray diffraction (XRD), nitrogen adsorption-desorption, and field-emission scanning electron microscopy (FESEM) techniques. The adsorption behaviors of the synthesized UiO-66s were then investigated by selecting anionic methyl red (MR) and cationic methylene blue (MB) as the model dyes. It was found that a change in... 

In the present work, mesoporous nitrogen-doped carbon nanotubes (N-CNTs) were synthesized by using a low-cost and unique set of precursors (camphor and urea). The CVD method at 1000 °C was used with different camphor/urea ratios, and Co-Mo/MgO nanocatalyst was utilized as growth catalyst. Application of mesoporous N-CNTs in selective oxidation of H2S was studied experimentally and N-CNTs interactions with H2S was also investigated using DFT calculations. The as-synthesized N-CNTs were characterized using FTIR, FE-SEM, elemental analysis, X-ray diffraction (XRD), XPS and nitrogen adsorption/desorption. The N-CNT2 sample with urea to camphor ratio (U/C) of 1 showed the highest sulfur yield at... 

Several SAPO-34 samples with different Si/Al ratio (0.05-0.5) of synthesis gel were prepared hydrothermally at crystallization temperature of 190-215 °C. The products were characterized by XRD, SEM/EDX, NH3-TPD, FT-IR and nitrogen adsorption techniques. EDX data showed a deviation of elemental composition of products with respect to the Al, Si, and P from that of the gel mixture, but the increasing trend of Si/Al ratio of the products was confirmed. According to XRD and SEM results, crystallinity of samples increased with Si/Al ratio up to the low to medium range of ca. 0.13. However, a reduction in the crystallinity was observed with further increase of the silicon content of the synthesis... 

Graphene reinforced polymer derived carbon (carbon/graphene) aerogels were synthesized by carbonization of novolac/graphene oxide aerogels. Novolac/graphene oxide aerogels were synthesized using solvent-saturated-vapor-atmosphere technique. To this aim, 20 wt% solution of novolac resin with 0, 2, and 5 wt% graphene oxide in 2-propanol were made and were cured in an autoclave. Wet aerogels were dried in air and were carbonized at 800 °C in nitrogen atmosphere. Eliminating the time-consuming methods of drying like supercritical and freeze drying is one of the advantages of this method of synthesis of organic aerogles. Fourier transform infrared spectroscopy, field emission scanning electron... 

TiO2 nanoparticles were prepared by the sol - gel process using 2-hydroxylethy- lammonium formate as an ionic liquid. Nanoparticles were crystallized at various temperatures (300-700°C). The products were characterized using X-ray diffraction (XRD), nitrogen adsorption - desorption isotherms and scanning electron microscopy (SEM) techniques. It was found that the resulting TiO2 nanoparticles had good thermal stability either to resist collapse or the anatase-to-rutile phase transformation during heat treatment. The photocatalytic activity of the nanocrystalline TiO2 was evaluated by the degradation of Acid Blue 92 (AB92) which is commonly used as a textile dye. The results showed that the...