Benzylation of some Aromatics using Metal Ferrite Catalysts

Abstract

Five ferrite catalysts(M2+Fe23+O2-4), whereM2+ represents Co2+,Ni2+, Fe2+, Zn2+orCa2+, were prepared byco-precipitation method, in whichone or more metals were precipitated together with the support or precursor. Chemical phases dispersion, surface areas, porous structure and particle size and shape were created in a single step. The synthesized ferrites were purified by washing with BaCl2solution till they were sulfate free.Theywere characterized by X-ray diffraction (XRD), to show a cubic spinel shape crystal structure. Their atomic absorption spectroscopic data (AAS)coincided with the optimum molar ratio of M2+: Fe3+2according to M2+ : Fe23+ : O2-41:2:4 formula. Fourier transform Infra-RedFT-IR showed two main peaksofthe Fe-Oand M-O, oneat υ1= 398-4000cm-1for Fe-Fer.,Co-Fer.,Ni-Fer.,Zn-Fer. and υ1*= 400-4000 cm-1for Ca-Fer. and the second at υ2=385- 600cm-1 corresponding to intrinsic stretching vibrations of the metal at the tetrahedral site (M tetra-O) and the metal at the octahedral site ( M octa- O). Scanning electron microscopy (SEM) photographs reflectthe topographic morphology of M-Ferrites of the irregular block-shaped agglomerates. The prepared ferrites were used as catalyst to benzylate toluene, xylene and benzene using benzyl chloride (BC). Following the reactions with the gas chromatography, the results confirmedhigh activity of ferrites to catalyze benzylation reaction between benzyl chloride (BC) and the some aromatics. These reactions were studied at different conditions, such as temperature ( 90, 80, 70, 60, 50 ºC), molar ratio: ( 1:5, 1:10, 1:15and 1:20), weight of catalyst: (0.05, 0.07, 0.1 and 0.15g), type of catalyst: ( Fe2+- Fer., Co2+- Fer., Ni2+- Fer., Ca2+-Fer. and Zn2+-Fer.) and reaction time(0 to 3 hours). The optimum conditions for benzylation were as follows: xylene (70 ºC, 1:15, 0.1g weight of catalyst and Fe-fer. type of catalyst),benzene (60 ºC, 1:15, 0.1g weight of catalyst and Fe-fer. type of catalyst)and toluene (60 ºC, 1:20, 0.1g weight of catalyst and Fe-fer. type of catalyst). The results showed a noticeablereusability and leaching tests for the catalysts.The reaction productswere monitored by gas chromatographic separation with a flame ionization detector, the outcome of the results representedincreased catalytic activity in, xylene, benzene and toluene respectively.This work provedthat ferrites are good catalysts for benzylation of benzene, toluene and xylene.