Activation of ethyl acetate over metal substituted MCM-41: application to alkylation and acylation

Al-MCM-41, Fe,Al-MCM-41 and Zn,Al-MCM-41 materials with different silicon to metal ratios were synthesized hydrothermally and characterized by XRD, BET, FT-IR, Acidity measurement by pyridine adsorbed FT-IR spectroscopy, ²⁹Si and ²⁷Al MAS NMR and ESR techniques. The orderly arrangement of mesoporous materials was clearly revealed from the XRD patterns. ²⁹Si and ²⁷Al MAS NMR established the co-ordination environment of silicon and aluminium. Electron paramagnetic resonance (EPR) study confirmed the co-ordination environment of Fe in Fe,Al-MCM-41 framework. The catalytic activity of these materials was evaluated in the vapour phase alkylation and acylation of ethylbenzene with ethyl acetate in the temperature range between 250 and 400 °C. The products were found to be 1,3-diethylbenzene (1,3-DEB), 1,4-diethylbenzene (1,4-DEB), 1,2-diethylbenzene (1,2-DEB), 4-ethylacetophenone (4-EAP) and acetophenone (AP). The reaction products revealed that activation of ethyl acetate is a convenient route for both alkylation and acylation reactions. The order of the catalysts activity for the reaction is found to be Fe,Al-MCM-41 (50) > Fe,Al-MCM-41 (100) > Zn,Al-MCM-41 (50) > Zn,Al-MCM-41 (100) > Al-MCM-41 (50) > Al-MCM-41 (100). In addition to the density of acid sites, the strength of acid sites is also important for this reaction. The effects of temperature, feed ratio, WHSV and time on stream were also examined and the results are discussed.     

Selective ion-exchange in MAPO-36 and its application in toluene disproportionation

MAPO-36 was synthesized hydrothermally by isomorphic substitution of Mg²⁺ in the framework of AlPO-36 and ion-exchanged with Fe³⁺, Zn²⁺, La³⁺ and Ce³⁺ by wet method. The materials were characterized by XRD, TGA, TPD (ammonia) and SEM-EDX. XRD revealed absence of structural degradation after ion-exchange. TPD (ammonia) showed selective ion-exchange of strong acid sites in ion-exchanged MAPO-36. The weight loss around 550 °C in TGA for Fe, La and CeMAPO-36 suggested conversion of M(OH)₂⁺ to MO⁺. Toluene disproportionation was carried over all catalysts in which diphenyl methane derivative was suggested to be the principle intermediate in the formation of p-xylene and other products. The time on stream study showed exclusive formation of p-xylene after 6 h.     

Copolymer/Clay Nanocomposites for Biomedical Applications

Nanoclays still hold a great strength in biomedical nanotechnology applications due to their exceptional properties despite the development of several new nanostructured materials. This article reviews the recent advances in copolymer/clay nanocomposites with a focus on health care applications. In general, the structure of clay comprises aluminosilicate layers separated by a few nanometers. Recently, nanoclay‐incorporated copolymers have attracted the interest of both researchers and industry due to their phenomenal properties such as barrier function, stiffness, thermal/flame resistance, superhydrophobicity, biocompatibility, stimuli responsiveness, sustained drug release, resistance to hydrolysis, outstanding dynamic mechanical properties including resilience and low temperature flexibility, excellent hydrolytic stability, and antimicrobial properties. Surface modification of nanoclays provides additional properties due to improved adhesion between the polymer matrix and the nanoclay, high surface free energy, a high degree of intercalation, or exfoliated morphology. The architecture of the copolymer/clay nanocomposites has great impact on biomedical applications, too, by providing various cues especially in drug delivery systems and regenerative medicine.     

Failure Analysis of Motorized Bellow-Sealed Valve of Sodium Loop in Fast Breeder Test Reactor

Journal of Failure Analysis and Prevention - A motorized bellow-sealed valve in the steam generator leak detection circuit of fast breeder test reactor developed sodium leak while carrying out...     

Scalable Lanthanum Titanate (La2Ti2O7) nanostructures as UV photodetectors

Thermally and chemically stable perovskite-like layer structures have attracted extensively in the field of energy and environmental applications. In this study, La₂Ti₂O₇ was synthesized by the solvothermal method at 180 °C. This method provides high pure and homogeneously dispersed nanorods of orthorhombic phase having length of 250 nm and width of 70 nm. Even though this is a low-temperature synthesis method, it yields high crystalline nature after calcination. The novelty of this work is its synthesis methodology by the solvothermal route to achieve lower weight loss of La₂Ti₂O₇. Furthermore, they exhibit narrow absorption in the UV-region from 200 to 350 nm, makes it possible to fabricate it as UV photodetector at ambient condition. In presence of UV illumination at 390 nm, it shows sharp photocurrent response with the decay time of 1.7 s.

     

Microstructural,Optical, Morphological,Luminescence and Electrical Properties of a CdO Nanocomposite Synthesized by a Chemical Route Assisted Microwave Irradiation Technique

This article reports a CdO nanocomposite successfully synthesized by a chemical route assisted microwave irradiation technique. Sodium dodecyl benzene sulfonate (SDBS) is a good surfactant and it is used in forming the nanocomposite. The microwave irradiation technique is simple and less time consuming for preparing a nanocomposite. The obtained products were characterized by different techniques such as X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR), UV-Vis DRS, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), room temperature photoluminescence (PL), and DC electrical conductivity. The grain size determined by the XRD pattern was found to be 20–40 nm. The lattice fringes and nanocomposite morphology particle size were obtained by TEM. The room temperature PL spectra reveal blue and red emissions. The calculated average electrical conductivity was around 5.1 × 10⁻⁸ to 2.02 × 10⁻⁸ S/cm.

     

Preparation and characterization of camptothecin-loaded alginate/poly[N-(2-hydroxypropyl) methacrylamide] hydrogel beads for anticancer treatment

Encapsulation of poor water-soluble drugs into a biocompatible polymeric matrix is a good strategy for in vitro drug delivery. Present study deals with the preparation and optimization of alginate/poly[N-(2-hydroxypropyl) methacrylamide] beads (SA/pHPMA) for the delivery of an anticancer drug such as camptothecin (CPT). Beads were prepared by ionotropic gelation technique using calcium chloride and optimized concentrations of 10?w/v% of sodium alginate beads and 10:10?w/v% of poly[N-(2-hydroxypropyl) methacrylamide]:sodium alginate (SA/pHPMA) beads were prepared. Twenty ppm of CPT was incorporated into the beads by the imbibition method. XRD, thermogravimetric analysis, and differential scanning calorimetry studies of the beads showed no free pHPMA and CPT indicating their uniform dispersion into the matrix. FTIR analysis showed weak interaction between CPT and polymers. In vitro release of CPT from SA/pHPMA beads showed slow and sustained release of 80% while SA beads showed 62% retaining the shape of the beads in phosphate-buffered saline at pH 7.4. The presence of CPT inside the prepared beads has the potential to be used as soft bandages for treatment of cancer.     

Microencapsulation of hazelnut oil through spray drying

This study was performed to investigate the influence of air inlet temperature (AIT) on the microencapsulation of hazelnut oil by spray drying. Encapsulated powders were analyzed for moisture content, powder yield, surface oil, encapsulation efficiency (EE), bulk density, and particle morphology. The obtained results demonstrated that moisture content, surface oil, and bulk density decreased by 37.8, 27.5, and 33%, respectively as AIT increased from 140 to 220°C. However, powder yield and encapsulation efficiency increased considerably with the rise in AIT. Higher EEs of about 75–80% were observed in this study.