Cochin University of Science and Technology

About: Cochin University of Science and Technology is a education organization based out in Kochi, Kerala, India. It is known for research contribution in the topics: Thin film & Natural rubber. The organization has 5382 authors who have published 7690 publications receiving 103827 citations. The organization is also known as: CUSAT & Cochin University.

Selective benzoylation of o-xylene to 3,4-dimethylbenzophenone using various zeolite catalysts

Abstract: The liquid phase benzoylation of o -xylene with benzoyl chloride (BOC) over various zeolite catalysts is studied in a batch reactor at atmospheric pressure and 411 K. The results obtained over different zeolite catalysts are compared with the homogeneous Lewis acid catalyst, AlCl 3 and amorphous silica–alumina. The protonic form of zeolite beta is found to be an efficient catalyst compared to other zeolites in the benzoylation of o -xylene. The conversion of BOC, turnover rate of BOC conversion (TOF) and selectivity for 3,4-dimethylbenzophenone (3,4-DMBP) over zeolite H-beta are found to be 52.8 wt.%, 69.7×10 −5 s −1 mol −1 Al and 94.7 wt.%, respectively, at the following reaction conditions [H-beta to BOC (w/w)=0.28, o -xylene to BOC (molar ratio)=5; 411 K; 1 atm]. The non-shape selective AlCl 3 catalyst produces higher amount of consecutive products (16.2 wt.%) and hence gives lower selectivity for 3,4-DMBP (76.5 wt.%). The acidity and pore structure of H-beta appeared to be responsible for good performance. Increase in reaction time, catalyst concentration, reaction temperature, o -xylene to BOC molar ratio enhances the conversion of BOC, whereas it decreases with the increase in degree of Na-exchange and SiO 2 /Al 2 O 3 molar ratios of H-beta. The zeolite H-beta is recycled three times without the loss of 3,4-DMBP selectivity but with a decline in the catalytic activity of H-beta. Additionally, the benzoylation of m -xylene and p -xylene is also investigated using H-beta. The Friedel–Crafts acylation reaction mechanism involves the formation of an electrophile (C 6 H 5 CO + ) over an acidic zeolite catalyst which attacks the xylene ring resulting in the formation of dimethyl benzophenones.

Magnetic and processability studies on rubber ferrite composites based on natural rubber and mixed ferrite

Abstract: Polycrystalline single phasic mixed ferrites belonging to the series Ni1−xZnxFe2O4 for various values of x have been prepared by conventional ceramic techniques. Pre-characterized nickel zinc ferrites were then incorporated into a natural rubber matrix according to a specific recipe for various loadings. The processability and cure parameters were then determined. The magnetic properties of the ceramic filler as well as the ferrite loaded rubber ferrite composites (RFC) were evaluated and compared. A general equation for predicting the magnetic properties was also formulated. The validity of these equations were then checked and correlated with the experimental data. The coercivity of the RFCs almost resemble that of the ceramic component in the RFC. Percolation threshold is not reached for a maximum loading of 120 phr (parts per hundred rubber by weight) of the filler. These studies indicate that flexible magnets can be made with appropriate magnetic properties namely saturation magnetisation (Ms) and magnetic field strength (Hc) by a judicious choice of x and a corresponding loading. These studies also suggest that there is no possible interaction between the filler and the matrix at least at the macroscopic level. The formulated equation will aid in synthesizing RFCs with predetermined magnetic properties.