Vapor phase beckmann rearrangement of cyclohexanone oxime over different ferrierite zeolite catalysts

Ferrierite zeolite catalysts prepared using different procedures have been tested for their activity for vapor phase Beckmann rearrangement of cyclohexanone oxime to ε -caprolactam. We report here the results of a study seeking the influence of temperature, nitrogen feed rate, oxime concentration and solvents on the catalyst performance. At low concentration of oxime (2.5 wt%), using acetonitrile as solvent the maximum in the conversion of oxime and selectivity to ε -caprolactam has been obtained. The presence of weak, medium and strong acid sites as indicated by temperature-programmed desorption of NH3 corroborates well with the catalytic activities of various ferrierites shown here. Solvent polarity is found to significantly affect the conversion of cyclohexanone oxime

Physical and magnetic properties of barium calcium hexaferrite nano-particles synthesized by water-in-oil reverse micelle and co-precipitation techniques

BaCaB2BFeB16BOB27B hexaferrite particles were prepared using two different techniques namely (i) reverse micelle and (ii) co-precipitation with and without presence of surfactants (cationic, anionic and nonionic). The precipitate was calcinated at 950EsC for 4 hours and characterized by using various instrumental techniques. The structural studies of the samples were studied by using XRD and SEM. The field dependent magnetic properties of prepared Ba-Ca hexaferrite powder was investigated at room temperature by using vibrating sample magnetometer. It has been observed that the type of surfactant plays a crucial role in deciding the morphology of the particles. There is significant change in crystallite size of the resultant Ba-Ca hexaferrite prepared in presence of anionic surfactant sodium dodecyl sulfate (SDS) and reverse micelle route. The samples prepared in presence of cationic and non ionic surfactants show agglomerated large particles. Magnetic study reveals that the value of anisotropy constant (K) depends on the type of surfactant used. The sample prepared in presence of nonionic surfactant Polyethylene glycol sorbitan monooleate (Tween 80) shows low anisotropy constant (0.26×10P-3P HAP2P/kg) where as the sample prepared in presence of SDS surfactant exhibits high anisotropy constant (3.26×10P-3P HAP2P/kg) compared to normal sample (0.41 ×10P-3P HAP2P/kg)

Comparative analysis of co-processed starches prepared by three different methods

Co-processing is currently of interest in the generation of high-functionality excipients for tablet formulation. In the present study, comparative analysis of the powder and tableting properties of three co-processed starches prepared by three different methods was carried out. The co-processed excipients consisting of maize starch (90%), acacia gum (7.5%) and colloidal silicon dioxide (2.5%) were prepared by co-dispersion (SAS-CD), co-fusion (SAS-CF) and co-granulation (SAS-CG). Powder properties of each co-processed excipient were characterized by measuring particle size, flow indices, particle density, dilution potential and lubricant sensitivity ratio. Heckel and Walker models were used to evaluate the compaction behaviour of the three co-processed starches. Tablets were produced with paracetamol as the model drug by direct compression on an eccentric Tablet Press fitted with 12 mm flat-faced punches and compressed at 216 MPa. The tablets were stored at room temperature for 24 h prior to evaluation. The results revealed that co-granulated co-processed excipient (SAS-CG) gave relatively better properties in terms of flow, compressibility, dilution potential, deformation, disintegration, crushing strength and friability. This study has shown that the method of co-processing influences the powder and tableting properties of the co-processed excipient

Comparative analysis of co-processed starches prepared by three different methods

Co-processing is currently of interest in the generation of high-functionality excipients for tablet formulation. In the present study, comparative analysis of the powder and tableting properties of three co-processed starches prepared by three different methods was carried out. The co-processed excipients consisting of maize starch (90%), acacia gum (7.5%) and colloidal silicon dioxide (2.5%) were prepared by co-dispersion (SAS-CD), co-fusion (SAS-CF) and co-granulation (SAS-CG). Powder properties of each co-processed excipient were characterized by measuring particle size, flow indices, particle density, dilution potential and lubricant sensitivity ratio. Heckel and Walker models were used to evaluate the compaction behaviour of the three co-processed starches. Tablets were produced with paracetamol as the model drug by direct compression on an eccentric Tablet Press fitted with 12 mm flat-faced punches and compressed at 216 MPa. The tablets were stored at room temperature for 24 h prior to evaluation. The results revealed that co-granulated co-processed excipient (SAS-CG) gave relatively better properties in terms of flow, compressibility, dilution potential, deformation, disintegration, crushing strength and friability. This study has shown that the method of co-processing influences the powder and tableting properties of the co-processed excipient

Synthesis, characterization and catalytic performance of titanium silicalite-1 prepared in micellar media

Titanium silicalite-1 (TS-1) was synthesized in the presence of small amount of TPAOH using Tween 20, as nonionic surfactant. The procedure gives highly pure nanometer-sized homogeneous crystalline product and higher rate of crystallization. The results are compared with the TS-1 sample prepared without surfactant. Characterization of TS-1 has been carried out by using X-ray diffraction and shows that the samples are fully crystalline, while FTIR spectroscopy shows the presence of characteristic band for TS-1 at 960 cm-1, confirming Si-O-Ti linkages present in the product. The UV-visible spectroscopy of the sample prepared without surfactant at low TPAOH concentration shows the presence of extra framework of TiO2 species. Scanning electron micrograph (SEM) of the sample shows homogeneous particle size (~150 nm), while the sample without surfactant shows the presence of particle size ranging between 150 and 200 nm. Catalytic activity of TS-1 sample was also confirmed for octene epoxidation

Synthesis and characterization of dodecanethiol-capped cadmium sulfide nanoparticles in a winsor II microemulsion of diethyl ether/AOT/water

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Synthesis and magnetic properties of barium-calcium hexaferrite particles prepared by sol-gel and microemulsion techniques

The preparation of W-type hexaferrite particles with the composition BaCa2Fe16O27 by microemulsion and a stearic acid sol-gel method with and without surfactant has been investigated at various sintering temperatures. The structural and magnetic characteristics have been studied by X-ray diffraction (XRD), a vibrating sample magnetometer (VSM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential scanning calorimetric (DSC) and Fourier transform infrared (FTIR) techniques. The effect of sintering temperature on the properties of BaCa2Fe16O27 hexaferrites has been studied. The value of saturation magnetization (Ms) depends on types of surfactant used. The sample prepared in the presence of polyoxyethylene (20) sorbitan monooleat (Tween 80) shows low saturation magnetization (Ms=15.10 emu/g), whereas the other sample prepared in the presence of a surfactant cetyltrimethylammonium bromide (CTAB) exhibits high saturation magnetization (Ms=24.60 emu/g) compared to the normal sample

Barium hexaaluminate nanowhiskers synthesized by novel sol-gel process in reverse micellar media

Barium hexaaluminate (BHA) synthesized by coupling of sol-gel process in reverse microemulsions shows a unique nanowhisker morphology and high surface area, which are retained after calcination at 1300 °C