SMFs-supported Pd nanocatalysts in selective acetylene hydrogenation:Pore structure-dependent deactivation mechanism

In the present study,CNFs,ZnO and Al2O3 were deposited on the SMFs panels to investigate the deactivation mechanism of Pd-based catalysts in selective acetylene hydrogenation reaction.The examined supports were characterized by SEM,NH3-TPD and N2adsorption-desorption isotherms to indicate their intrinsic characteristics.Furthermore,in order to understand the mechanism of deactivation,the resulted green oil was characterized using FTIR and SIM DIS.FTIR results confirmed the presence of more unsaturated constituents and then,more branched hydrocarbons formed upon the reaction over alumina-supported catalyst in comparison with the ones supported on CNFs and ZnO,which in turn,could block the pores mouths.Besides the limited hydrogen transfer,N2 adsorption-desorption isotherms results supported that the lowest pore diameters of Al2O3/SMFs close to the surface led to fast deactivation,compared with the other catalysts,especially at higher temperatures.     

Optimization of synthesis procedure and structure characterization of manganese tungstate nanoplates

A simple and fast chemical method was used for synthesis of manganese tungstate nanoplates in flower-like clusters; while Taguchi robust design was employed as statistical method for optimization of the experimental parameters for the procedure. Ultrafine manganese tungstate plates in flower-like clusters were synthesized via a direct precipitation method involving addition of manganese ion solution to the aqueous tungstate reagent. Effects of various reaction conditions such as manganese and tungstate concentrations, flow rate of reagent addition and reactor temperature on the thickness of the synthesized manganese tungstate plates were investigated experimentally. Analysis of variance (ANOVA) showed that manganese tungstate nanoplates could be effectively synthesized by tuning significant parameters of precipitation procedure. Meanwhile, optimum conditions for synthesis of MnWO4 nanoplates via this simple, fast, and cost effective method were proposed. The structure and composition of the prepared nanoplates under optimum conditions were characterized by EDX, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), FT-IR spectroscopy, and photoluminescence techniques.      

Diammonium Hydrogen Phosphate: An Efficient and Versatile Catalyst for the One‐Pot Synthesis of Tetrahydrobenzo[b]pyran Derivatives in Aqueous Media

Diammonium hydrogen phosphate was used as a mild, efficient, neutral, and cheap catalyst for the synthesis of various 4H‐benzo[b]pyran derivatives via a one‐pot, three‐component condensation of aromatic aldehydes, active methylene compounds, and dimedone in aqueous media.     

Ultrasound-assisted emulsification microextraction using low density solvent for analysis of toxic nitrophenols in natural waters

An ultrasound-assisted emulsification microextraction (USAEME) based on low-density solvents was successfully applied for the extraction and pre-concentration of four toxic nitrophenols in water samples. The extracted analytes were analyzed by high-performance liquid chromatography-UV detection. The important parameters influencing the extraction efficiency were studied and optimized utilizing two different optimization methods: one variable at a time (OVAT) and central composite design (CCD). The results showed that the emulsification process can be completed in a few seconds using low-density solvents, but almost 10–20?min is necessary for high-density solvents. Under the optimum conditions (extraction solvent, 1-octanol; extraction solvent volume, 40?µL; sample pH, 3.0; salt concentration, 20% (w/v) NaCl; extraction temperature, 40 (±3)°C), limits of detection of the method were in the range of 0.25 to 1?µg?L^?1 and the repeatability and reproducibility of the proposed method, expressed as relative deviation, varied in the range of 2.2–4.2% and 4.7–6.9%, respectively. Linearity was found to be in the range of 1 to 200?µg?L^?1 and the preconcentration factors (PFs) were between 77 and 175. The relative recoveries of the four nitrophenols from water samples at spiking level of 10.0?µg?L^?1 were in the range of 92.0 to 115.0%.     

Exergetic and economic optimization of a solar-based cogeneration system applicable for desalination and power production

Journal of Thermal Analysis and Calorimetry - The selective drug delivery system could be an excellent alternative to fight cancer and pathogens, due to its minimized negative consequences....     

Mercuric chloride adsorption on sulfur-containing BC2N nanotube: toward HSAB concept

Electronic sensitivity of pristine and sulfur-containing BC₂N nanotubes to mercuric chloride (HgCl₂) molecule was investigated by utilizing density functional theory. It was found that HgCl₂ is weakly adsorbed on the tube, releasing energy of 6.4–8.1 kcal/mol, and electronic properties of the tube are not significantly changed. To overcome this problem, carbon atoms of the tube were substituted by sulfur atom. Of interest are sulfur derivative functional adsorbents because of their strong affinity toward mercury. This observation may be explained based on the Pearson’s hard–soft acid–base theory. It was demonstrated that the S-doped tube can not only strongly adsorb the HgCl₂ molecule, but also may effectively detect its presence due to drastic increment of the tube electrical conductivity.     

Synthesis,characterization and catalytic application of tributyl(carboxymethyl)phosphonium bromotrichloroferrate as a new magnetic ionic liquid for the preparation of 2,3-dihydroquinazolin-4(1H)-ones and 4H-pyrimidobenzothiazoles

Research on Chemical Intermediates - In this paper, tributyl(carboxymethyl)phosphonium bromotrichloroferrate as a new magnetic ionic liquid bearing acetic acid tags was synthesized and...