Low-angle X-ray Diffraction Research Articles

L-cysteine complex of palladium onto mesoporous channels of MCM-41 as reusable, homoselective and organic–inorganic hybrid nanocatalyst for the synthesis of tetrazoles

In this study, ordered structure with a hexagonal arrangement MCM-41 was synthesized and functionalized with L-cysteine group and further palladium particles has been supported on its surface (L-cysteine-Pd@MCM-41). The prepared catalyst is well characterized by various techniques such as low-angle X-ray diffraction (XRD), thermal gravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), N2 adsorption–desorption measurement isotherms, energy-dispersive X-ray spectroscopy (EDS), X-ray Mapping (WDX), scanning electron microscopy (SEM) and inductively coupled plasma (ICP) techniques. The collected data from all techniques provided evidence that palladium complex was immobilized onto MCM-41 pores. The obtained nanocatalyst demonstrated excellent activity as a new heterogeneous catalyst for the homoselective synthesis of 5-substituted 1H-tetrazole derivatives. This method has the advantages of simple methodology, eco-friendly and simplicity in the separation of catalyst, shorter reaction times, and high yields of the product. Finally, easy catalyst recovery was achieved and the catalyst could be recycled for six times without a significant decrease in activity and selectivity.

Capability of synthesized sulfonated aromatic cross-linked polymer covalently bonded montmorillonite framework in productivity process of biodiesel

Polystyrene clay nanocomposites represent a significant class of tailored materials that possess value-added properties based on their hybrid nature from organic and inorganic chemistry in their framework. Such materials had numerous applications extending from fire retardant properties, gas permeability, and catalysis. Herein, cross-linked polystyrene (CPS) and cross-linked polystyrene- organophilic montmorillonite (OMMT) nanocomposites (VO-MMT-PS) were prepared using 1,4-di(chloromethyl)benzene and ferric chloride as crosslinking agent and catalyst, respectively. The VO-MMT-CPS nanocomposites were prepared with 1, 3, and 5 wt% of MMT with respect to styrene to show the effect of the MMT layers on the properties of the polymer. The CPS and VO-MMT-CPS were post-sulfonated to create strong Brønsted acid sites on the surface of prepared materials. The prepared polymers are described by FTIR, N2–adsorption/desorption isotherms, TGA, and XRD techniques. The low angle XRD showed an increase in the OMMT layer after modification, and exfoliation structures are obtained after polymerization, whereas the entry of the OMMT layer in polymer structure increases the surface area of the polymer. The catalytic effects of the VO-MMT-CPS-SO3H nanocomposites were examined and compared to CPS-SO3H in the methanolysis of oleic acid to form the methyl oleate as a biodiesel model. The VO-MMT-CPS-SO3H that has a high OMMT ratio (5%) represented the highest catalytic performance in the methanolysis reaction with 89% conversion at 70 °C, 4% catalyst, 9:1 methanol: oleic acid molar ratio. Comparing 5% VO-MMT-CPS-SO3H to Amberlyst-15 as a commercial catalyst, the prepared catalysts exhibited better activity and higher thermal stabilities.

Optimization and Characterization of Aluminum Induced Texture Using Radio Frequency Power

The purpose of this study aims to investigate the surface morphology and roughness of Aluminum induced glass texturing (AIT) substrate after different surface treatments. Aluminum layers were deposited in thickness 370 nm and 240 nm on corning glass sheet using Radio Frequency (RF) power. The effect of different concentrations of hydrofluoric acid (HF), 4%, 5% and 6% on morphology, optical absorption and surface roughness of glass was described. The dipping time of coated glass sheet in HF for 2 min and 5 min created very rough and soft surface, respectively. Optical absorption of AIT substrate after dipping in HF was measured. The optimum texturing process achieved by deposition of aluminum layer 240 nm of thickness and dipping the substrate in 5% HF. The AIT substrate was characterized by low angle X-ray diffraction (XRD), ultraviolet-visible spectrophotometer (UV-VIS), stylus profiler and scanning electron microscope (SEM).

Synthesis of Fe2SiO4-Fe7Co3 Nanocomposite Dispersed in the Mesoporous SBA-15: Application as Magnetically Separable Adsorbent.

The mixture containing alloy and oxide with iron-based phases has shown interesting properties compared to the isolated species and the synergy between the phases has shown positive effect on dye adsorption. This paper describes the synthesis of Fe2SiO4-Fe7Co3-based nanocomposite dispersed in Santa Barbara Amorphous (SBA)-15 and its application in dye adsorption followed by magnetic separation. Thus, it was studied the variation of reduction temperature and amount of hydrogen used in synthesis and the effect of these parameters on the physicochemical properties of the iron and cobalt based oxide/alloy mixture, as well as the methylene blue adsorption capacity. The XRD and Mössbauer results, along with the temperature-programmed reduction (TPR) profiles, confirmed the formation of Fe2SiO4-Fe7Co3-based nanocomposites. Low-angle XRD, N2 isotherms, and TEM images show the formation of the SBA-15 based mesoporous support with a high surface area (640 m2/g). Adsorption tests confirmed that the material reduced at 700 °C using 2% of H2 presented the highest adsorption capacity (49 mg/g). The nanocomposites can be easily separated from the dispersion by applying an external magnetic field. The interaction between the dye and the nanocomposite occurs mainly by π-π interactions and the mixture of the Fe2SiO4 and Fe7Co3 leads to a synergistic effect, which favor the adsorption.

Fischer-Tropsch studies in a 3D-printed stainless steel microchannel microreactor coated with cobalt-based bimetallic-MCM-41 catalysts

Fischer-Tropsch (FT) synthesis was carried out using 3D-printed stainless steel (SS) microreactors, containing channels of dimensions 500 μm × 500 μm ×2.7 cm, to study the effect of Fe, Ru, and Ni on Co-MCM-41 catalyst. The mono and bimetallic cobalt-based catalysts: 15 % Co-MCM-41, 10 %Co5% Ru MCM-41, 10 %Co 5%Ni MCM-41, and 10 %Co 5%Fe MCM-41 were synthesized using one-pot hydrothermal method and characterized by SEM-EDX, TEM, TPR, FTIR, XPS, and low and wide angle XRD techniques. All the catalysts exhibited high surface area without the loss of ordered mesoporous structure as confirmed by large BET surface areas (400- 1000 m2/g) and low angle XRD data. The metal nanoparticles were in the range of 35−50 nm and well dispersed in a hexagonal matrix of MCM-41. TPR data indicate that all other metal oxides except that of cobalt can be reduced with H2 below 600 °C. Cobalt is present most likely as cobalt silicates that can only be reduced with H2 at a temperature over 650 °C. The microchannels of SS reactor were uniformly coated by dip coating a slurry of the catalyst with polyvinyl alcohol (PVA). The catalytic performance for FT synthesis was carried out in the SS microreactor at atmospheric pressure in the temperature range of 180–300 °C with H2/CO molar ratio of 3. Incorporation of the second metal in the Co-MCM-41 framework and the operating temperature had a significant effect on CO conversion and selectivity towards C1-C4 alkanes in FT synthesis. While the highest CO conversion of 74 % was obtained for CoFe-MCM-41 at 240 °C, the highest selectivity towards butane (11 %) and propane (39 %) was observed for CoRu-MCM-41 at 240 °C and CoFe-MCM-41 at 210 °C, respectively. The rate of deactivation of the catalysts -followed the order: CoRu-MCM-41> CoNi-MCM-41> Co-MCM-41> CoFe-MCM-41, indicating that CoFe-MCM-41 is the most suitable catalyst for F–T synthesis in terms of long term stability.

Controllable release activity of antibacterial Ag/SBA-16 cage-like synthesized by one-pot method

Abstract Without any chemicals, novel Ag/SBA-16 with well-ordered Im3m cubic cage-like pore was synthesized by one-pot method. Also, antibacterial ability and duration of Ag/SBA-16 was compared against Ag/SBA-15 based on their pore structure, loading, and releasing. Pore structure of particles were investigated by low angle X-ray diffraction (XRD) and Brunauer-Emmett-Teller (BET) analyses. Loading, releasing, properties of loaded Ag particles were studied by Inductively coupled plasma mass spectroscopy (ICP), Transmission electron microscope (TEM), and Energy-dispersive X-ray spectroscopy (EDAX). Ag/SBA-16 increases loaded Ag to 6.7% by weight due to its higher specific surface area. Also, it shows more controllable releasing due to narrower entrance pore size and trapping silver nanoparticles. These phenomena help Ag/SBA-16 to show more intensive and longer (more than 72 h) antibacterial activities against Ag/SBA-15.

KBTBD13 is an actin-binding protein that modulates muscle kinetics.

The mechanisms that modulate the kinetics of muscle relaxation are critically important for muscle function. A prime example of the impact of impaired relaxation kinetics is nemaline myopathy caused by mutations in KBTBD13 (NEM6). In addition to weakness, NEM6 patients have slow muscle relaxation, compromising contractility and daily life activities. The role of KBTBD13 in muscle is unknown, and the pathomechanism underlying NEM6 is undetermined. A combination of transcranial magnetic stimulation-induced muscle relaxation, muscle fiber- and sarcomere-contractility assays, low-angle x-ray diffraction, and superresolution microscopy revealed that the impaired muscle-relaxation kinetics in NEM6 patients are caused by structural changes in the thin filament, a sarcomeric microstructure. Using homology modeling and binding and contractility assays with recombinant KBTBD13, Kbtbd13-knockout and Kbtbd13R408C-knockin mouse models, and a GFP-labeled Kbtbd13-transgenic zebrafish model, we discovered that KBTBD13 binds to actin - a major constituent of the thin filament - and that mutations in KBTBD13 cause structural changes impairing muscle-relaxation kinetics. We propose that this actin-based impaired relaxation is central to NEM6 pathology.

Self-organization of silicates on different length scales exemplified by amorphous mesoporous silica and mesoporous zeolite beta using multiammonium surfactants.

In this study the structure directing effect of a gemini-type piperidine-based multi-ammonium surfactant during hydrothermal zeolite synthesis was investigated for two cases: with and without a source of aluminum. The absence of an aluminum source led to the formation of an amorphous mesoporous MCM-48 type silica material, while the presence of aluminum guaranteed the formation of zeolite beta with a hierarchical pore system. The two opposing cases were studied in a time and temperature-dependent manner. The mobility and through space interaction of these large surfactant molecules were studied by liquid state nuclear magnetic resonance (NMR) at a temperature relevant to hydrothermal synthesis (363 K) in pure water and upon addition of an aluminum and silicon source. In the gel state, at different stages of aging and hydrothermal synthesis, low angle X-ray diffraction (XRD) and solid state magic angle spinning nuclear magnetic resonance (1H MAS NMR) spectrometry determined the developing order within the system. At each of these different synthesis steps the respective intermediate materials were calcined. Transmission electron microscopy then allowed closer inspection of the locally developing mesoscopic order, while N2 physisorption was used to follow the evolution of porosity.

Efficacy-shaping nanomedicine by loading Calcium Peroxide into Tumor Microenvironment-responsive Nanoparticles for the Antitumor Therapy of Prostate Cancer.

Rationale: Prostate cancer has become one of the most threatening malignant tumors in men, leading to an imperative need to develop effective and safe therapies. Because of the unique metabolism of tumor cells, the tumor microenvironment (TME) exhibits distinctive properties compared with normal tissues, among which the pH difference has been utilized as an ideal antitumor strategy. Herein, we introduce a reactive oxygen species (ROS)-controlled-release nanosystem with TME-responsiveness by applying hollow mesoporous silica nanoparticles (HMSNs) as carriers loaded with calcium peroxide (CaO2) and coated with polyacrylic acid (PAA) to construct the functional material CaO2@HMSNs-PAA. The differences in pH values and exogenous ROS scavenging abilities between the tumor tissue and normal tissues and the dual pH-responsiveness from CaO2 and PAA lay a scientific foundation for the application of CaO2@HMSNs-PAA in the tumor-selective therapy for prostate cancer.Methods: The morphology and the structure of the nanosystem were characterized by the transmission electron microscope, scanning electron microscope, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, zeta potential, dynamic light scattering measurement, low-angle X-ray diffraction patterns and nitrogen adsorption/desorption isotherm. The CaO2 loading capacity and release profiles in different buffer solutions were determined by inductively coupled plasma-mass spectrometry. The in vitro intracellular uptake of CaO2@HMSNs-PAA was explored on the PC-3 prostate cancer cell line via confocal laser scanning microscopy. The CCK-8 cell proliferation assay was conducted to evaluate the cytotoxicity of CaO2@HMSNs-PAA against PC-3 cells. ROS produced by CaO2@HMSNs-PAA was observed by a fluorescence microscope. The flow cytometry was utilized to analyze the apoptosis of PC-3 cells induced by CaO2@HMSNs-PAA. The Western blot analysis was performed to detect expressions of critical mitochondria-mediated apoptosis markers in PC-3 cells after incubation with CaO2@HMSNs-PAA. The in vivo biosafety and antitumor efficacy were evaluated out on BALB/c mice and BALB/c nude mice subcutaneously transplanted with PC-3 cells, respectively.Results: Comprehensive characterizations indicated the successful synthesis of CaO2@HMSNs-PAA with significant TME-responsiveness. The experimental results demonstrated that the well-developed nanocarrier could efficiently deliver CaO2 to the tumor site and release ROS in response to the decreased pH value of TME, exerting ideal antitumor effects both in vitro and in vivo by activating the mitochondria-mediated apoptosis pathway. Simultaneously, this nanoplatform caused no detectable damage to normal tissues.Conclusions: After loading into the above nanocomposite, the free CaO2 without a significant antitumor effect can exert excellent antitumor efficacy by responsively releasing ROS under the acidic TME to induce the mitochondria-mediated apoptosis via remarkable oxidative stress and simultaneously minimize damages to normal tissues. The current study presents a new concept of “efficacy-shaping nanomedicine” for the tumor-selective treatment of prostate cancer.

Al30-PILLARED MONTMORILLONITE WITH ENHANCED TEXTURAL PROPERTIES DUE TO PRELIMINARY MECHANICAL TREATMENT

The effect of mechanical treatment of natural montmorillonite in a planetary-centrifugal mill on the efficiency of intercalating aluminum polyhydroxocomplexes [Al30O8(OH)56(H2O)26]18+ in the formation of pillared structures was studied. Measurements made using the photometry method showed that in the montmorillonite matrix, after intercalation of the Al30 polyhydroxocomplexes using mechanical treatment, an increase in the content of Al3+ cations by 13% was observed. According to the electrophoretic light scattering data, the particle size for the suspension of mechanically activated montmorillonite dispersed in water was about 100 nm. The raw, mechanically activated and pillared montmorillonites are characterized by the methods of low-angle X-ray diffraction, scanning electron microscopy, and low-temperature nitrogen adsorption-desorption. It was shown that preliminary mechanical activation of the initial substrate increases the basal distance d001 and significantly (approximately by 45–50%) increases the specific surface area and the total pore volume of Al30-pillared montmorillonite; in this case, both meso- and microporosity increase, and the pore size decreases by about 12%. The special importance of the size of montmorillonite particles during the intercalation and further formation of the pillared structure is shown. А decrease in the size of the montmorillonite particles during mechanical treatment increasing the area of the interphase boundary through which ion exchange takes place. It was shown that the small sizes of tactoids (about 100 nm) in an aqueous suspension play a key role in increasing the cation exchange capacity of mechanically activated montmorillonite. To a lesser extent, the efficiency of intercalation is influenced by the processes of defect formation and the related changes in the electrical properties of the silicate layers of montmorillonite. Based on the structural properties, the obtained pillared materials can be recommended for use as selective adsorbents, molecular sieves and catalysts.

Synthesis of n-Butyl Levulinate Using Mesoporous Zeolite H-BEA Catalysts with Different Catalytic Characteristics

The present work focuses on the utilization of waste biomass for the improvement of key catalytic properties of conventional zeolite H-BEA. In the present endeavor, zeolite H-BEA has been modified using cetyltrimethyl ammonium bromide (CTAB) and rice husk (a waste biomass resource), via desilication post synthetic route, which is not reported so far. The synthesized mesoporous zeolite H-BEA catalysts have been characterized by various characterization techniques such as, SEM, 27Al and 29Si MAS-NMR, wide and low angle XRD, ICP-OES, FT-IR, TGA, NH3-TPD and BET surface area. The resultant mesoporous zeolite materials (MCCK and MCRK) exhibited bimodal porosity as well as improved physicochemical properties, and the utility of these modified zeolites as heterogeneous catalysts has been demonstrated in the production of n-butyl levulinate via levulinic acid (LA) esterification. The catalytic material, which has been modified using CTAB and rice husk, is found to exhibit better catalytic activity towards the synthesis of n-butyl levulinate (95.6%) as compared to other zeolite counterparts under the optimised reaction conditions, which is attributed to its enhanced surface area and lower Si/Al ratio as compared to other catalysts under study.

Kinetics of Fischer–Tropsch Synthesis in a 3-D Printed Stainless Steel Microreactor Using Different Mesoporous Silica Supported Co-Ru Catalysts

Fischer–Tropsch (FT) synthesis was carried out in a 3D printed stainless steel (SS) microchannel microreactor using bimetallic Co-Ru catalysts on three different mesoporous silica supports. CoRu-MCM-41, CoRu-SBA-15, and CoRu-KIT-6 were synthesized using a one-pot hydrothermal method and characterized by Brunner–Emmett–Teller (BET), temperature programmed reduction (TPR), SEM-EDX, TEM, and X-ray photoelectron spectroscopy (XPS) techniques. The mesoporous catalysts show the long-range ordered structure as supported by BET and low-angle XRD studies. The TPR profiles of metal oxides with H2 varied significantly depending on the support. These catalysts were coated inside the microchannels using polyvinyl alcohol and kinetic performance was evaluated at three different temperatures, in the low-temperature FT regime (210–270 °C), at different Weight Hourly Space Velocity (WHSV) in the range of 3.15–25.2 kgcat.h/kmol using a syngas ratio of H2/CO = 2. The mesoporous supports have a significant effect on the FT kinetics and stability of the catalyst. The kinetic models (FT-3, FT-6), based on the Langmuir–Hinshelwood mechanism, were found to be statistically and physically relevant for FT synthesis using CoRu-MCM-41 and CoRu-KIT-6. The kinetic model equation (FT-2), derived using Eley–Rideal mechanism, is found to be relevant for CoRu-SBA-15 in the SS microchannel microreactor. CoRu-KIT-6 was found to be 2.5 times more active than Co-Ru-MCM-41 and slightly more active than CoRu-SBA-15, based on activation energy calculations. CoRu-KIT-6 was ~3 and ~1.5 times more stable than CoRu-SBA-15 and CoRu-MCM-41, respectively, based on CO conversion in the deactivation studies.

Enhanced Activation of Persulfate by Meso-CoFe2O4/SiO2 with Ultrasonic Treatment for Degradation of Chlorpyrifos.

Magnetic mesoporous CoFe2O4/SiO2 (Meso-CoFe2O4/SiO2) composites were simply synthesized. On the basis of previous studies, optimum preparation conditions of their structure and physical properties can be readily determined. CoFe2O4 nanocrystals and their mesoporous structure were authenticated by low-angle and wide-angle X-ray diffraction, high-resolution transmission electron microscopy, scanning electron microscopy, element mapping, X-ray photoelectron spectroscopy, nitrogen adsorption isotherms, and so on. They were applied to degrade chlorpyrifos where Meso-CoFe2O4/SiO2 composites provide a mesoporous microenvironment and combined with ultrasonic treatment can enhance heterogeneous activation of persulfate. Research findings showed that the system can be conducive to remove quickly chlorpyrifos and the removal ratios reached 99.99%. The results provided a strategy for the chlorpyrifos degradation and, similarly, pollution control of pesticide wastewater.

Effect of Ni loading on SBA-15 synthesized from palm oil fuel ash waste for hydrogen production via CH4 dry reforming

The successful synthesis of SBA-15 using silica source extracted from palm oil fuel ash (POFA) was proven with the presence of mesostructure characteristics as evidenced by low angle XRD, N2 adsorption-desorption isotherms and TEM. Different amounts of Ni were loaded on the synthesized SBA-15(POFA) using the impregnation method at 80 °C. The influence of Ni loading over the Ni/SBA-15(POFA) physiochemical properties and CO2 reforming of CH4 (CRM) were investigated in a stainless steel fixed-bed reactor at 800 °C and atmospheric pressure with 1:1 CO2:CH4 volumetric feed composition. An increment in Ni loading on SBA-15(POFA) from 1 to 5 wt% decreased the BET surface area and crystallinity of catalyst as proven by N2 adsorption–desorption and XRD analysis. The catalytic performance of CRM followed the sequence of 3 wt% > 5 wt% > 2 wt% > 1 wt% -Ni/SBA-15(POFA). This result was owing to the even distribution of Ni and good Ni–O–Si interaction of 3 wt% Ni/SBA-15(POFA) as proved by TEM, FTIR and XPS. Lowest H2/CO ratio and catalyst activity and stability of 1 wt% Ni/SBA-15(POFA) were due to the weaker Ni–O–Si interaction and small amount of basic sites that favor the reverse water gas shift (RWGS) reaction and carbon formation. The recent finding indicates that a quantity as small as 3 wt% Ni loaded onto SBA-15(POFA) could elicit outstanding catalytic performance in CRM, which was comparable with 10 wt% Ni loading catalysts reported in literature.

Synthesis of ordered mesoporous silicas from rice husk with tunable textural properties

Abstract Ordered mesoporous silicas were synthesized via cooperative self-assembly by using rice husk ash as silica source and P123 as main pore structure-directing agent. The incorporation of CTAB and BRIJ C10 as co-surfactant templates by different methods was investigated. Silicas with different pore size and mono-, bi- and trimodal porosity were obtained as a function of the co-surfactant used and the hydrolysis step performed. Low-angle XRD and TEM results confirmed the well-ordered pore structure of the synthesized silicas.

The Interacting Head Motif Structure Does Not Explain the X-Ray Diffraction Patterns in Relaxed Vertebrate (Bony Fish) Skeletal Muscle and Insect (Lethocerus) Flight Muscle.

Unlike electron microscopy, which can achieve very high resolution but to date can only be used to study static structures, time-resolved X-ray diffraction from contracting muscles can, in principle, be used to follow the molecular movements involved in force generation on a millisecond timescale, albeit at moderate resolution. However, previous X-ray diffraction studies of resting muscles have come up with structures for the head arrangements in resting myosin filaments that are different from the apparently ubiquitous interacting head motif (IHM) structures found by single particle analysis of electron micrographs of isolated myosin filaments from a variety of muscle types. This head organization is supposed to represent the super-relaxed state of the myosin filaments where adenosine triphosphate (ATP) usage is minimized. Here we have tested whether the interacting head motif structures will satisfactorily explain the observed low-angle X-ray diffraction patterns from resting vertebrate (bony fish) and invertebrate (insect flight) muscles. We find that the interacting head motif does not, in fact, explain what is observed. Previous X-ray models fit the observations much better. We conclude that the X-ray diffraction evidence has been well interpreted in the past and that there is more than one ordered myosin head state in resting muscle. There is, therefore, no reason to question some of the previous X-ray diffraction results on myosin filaments; time-resolved X-ray diffraction should be a reliable way to follow crossbridge action in active muscle and may be one of the few ways to visualise the molecular changes in myosin heads on a millisecond timescale as force is actually produced.

Synthesis of mesoporous silica for adsorption of chlordiazepoxide and its determination by HPLC: Experimental design.

In this work, mesoporous silica (SBA-15-NH2 ) was used as an efficient adsorbent for extraction of chlordiazepoxide from different samples based on dispersive nanomaterial-ultrasound assisted microextraction followed by high-performance liquid chromatography. The prepared sorbent was characterized by fourier transform infrared spectroscopy, scanning electron microscopy, low-angle X-ray diffraction, thermal analysis, and N2 adsorption-desorption surface area measurement. Several variables affecting the extraction efficiency of the chlordiazepoxide, including the amounts of adsorbent, time of adsorption, pH and volume of desorption solvent were optimized by central composite design combined with desirability function. The values of variables were set as 10mg of SBA-15-NH2 , 15min adsorption time, pH=7.3 and 1mL methanol. The linear response (0.998) was obtained in the range of 0.006-10µgmL-1 with detection limit 0.0014 µg/mL and extraction recovery was in the range of 91-96% with relative standard deviation<6%.

Mercury removal from aqueous solution via functionalized mesoporous silica nanoparticles with the amine compound

Studying the mercury removal from aqueous system using cubic mesoporous (Korea advanced institute of science and technology, KIT–6) and ethylenediamine functionalized KIT–6 (DA-KIT–6) silica materials were examined. The prepared KIT–6 and DA-KIT–6 were identified by FTIR, low–angle X-ray diffraction, Raman spectroscopy, 29Si NMR, BET, and HR-TEM. The removal of Hg2+ by adsorption was studied by applying various conditions such as the initial concentration of mercury ions, silica or modified silica amounts, contact time, and pH. Parameter optimization showed that the rate of Hg2+ adsorption of DA-KIT-6 is better than mesoporous KIT-6, which gave equilibrium adsorption rate of 95.9% and 82.5%, respectively, after 60 min at room temperature. The explanation of this behavior is due to the presence of ethylenediamine functionalized groups, –NH-(C2H4)–NH2, which have the ability to absorb Hg2+ ions from the aqueous solution. The thermodynamic calculations showed that the values of ΔG0, ΔS0, and ΔH0 were negative, which indicates that the adsorption of Hg2+ on the prepared silicas materials is exothermic and more energetically favorable sorption. The negative value of ΔS0 considers a decrease in the randomness at the sorbents–solution/interface during the Hg2+ adsorption onto the pores of silica materials (KIT-6 and DA-KIT-6).

Catalytic oxidation of sulfur compounds over Ce-SBA-15 and Ce-Zr-SBA-15

The catalytic oxidation of different sulfur compounds, commonly present in liquid fuel, was studied over a series of ceria and ceria-zirconium based oxidation mesoporous catalysts. SBA-15 was synthesized using sol-gel method and Ce and Ce-Zr were added by two different procedures: i) directly during the synthesis and ii) via post-synthesis method. The catalysts were characterized by XRD, N2 adsorption isotherms, XPS, DRUV-Vis, TEM, SEM and Py-FTIR. Low angle XRD, N2 isotherms and TEM confirmed that the structure was not changed after metal incorporation. Wide angle XRD, UV–vis-DRS, XPS and TEM determined that the catalysts prepared by direct synthesis presented higher dispersion of Ce oxides, smaller particle size and isolated Zr4+ species. FTIR of adsorbed/desorbed pyridine indicated that zirconium as promoter increases the Lewis acidity of the catalysts, especially during direct synthesis. Ce-Zr-SBA-15 catalyst prepared by direct synthesis was very active in the oxidation of dibenzothiophene, 4,6-dimethyl dibenzothiophene and benzothiophene using hydrogen peroxide (H2O2) as oxidant agent and acetonitrile as polar solvent. The effect of acidity in the catalyst, hydrogen peroxide concentration and temperature was studied. The deactivation test demonstrated that the catalyst is stable and adequate for the industrial process.

Ruthenium-Based Macromolecules as Potential Catalysts in Homogeneous and Heterogeneous Phases for the Utilization of Carbon Dioxide.

Ruthenium-containing tetraphenylporphyrin (Ru-TPP) molecule was prepared, and the structural elucidation was confirmed using 1H nuclear magnetic resonance (NMR), CHN, and mass spectral analyses. The incorporation of ruthenium ion into the cavities of the macromolecule was confirmed from the disappearance of the 1H NMR signal, characteristic of the N–H bond (−2.72 ppm in TPP). The CHN and mass spectral analyses of the ligand and metallomacromolecules are consistent with the theoretically calculated values. The homogeneous Ru-TPP macromolecule is grafted on the surface of aminosilane-, diaminosilane-, and iodosilane-functionalized SBA-15 molecular sieves. The successful grafting of Ru-TPP on functionalized mesoporous molecular sieve materials was evident from low-angle powder X-ray diffraction, 13C magic angle spinning NMR, and scanning electron microscopy–energy-dispersive X-ray analyses. The resultant homogeneous and heterogenized Ru-TPP catalysts were used for the utilization of carbon dioxide (CO2) under moderate reaction conditions. The homogeneous Ru-TPP catalyst showed first-order kinetics with respect to epoxide with the exclusive formation of cyclic carbonate (about 98%) and an activation energy of 16.07 kg/mol, which is much lower than some of the reported catalysts. Ru-TPP grafted on aminosilane- and iodosilane-functionalized materials showed better catalytic activity (above 90% conversion and 83–96% cyclic carbonate selectivity) and reusability for the chosen reaction.