Alkylation of benzene over Fe-based metal organic frameworks (MOFs) at low temperature condition

Abstract

Iron based metal organic frameworks as novel catalysts were developed for ethylbenzene synthesis by alkylation of benzene with ethanol in low temperature gas phase conditions employing MIL-101 (Fe) and MIL-88 (Fe) catalysts. Both of catalysts were synthesized with solvothermal method. Catalysts characterization were performed using X-Ray Diffraction (XRD), Fourier Transform Infrared spectroscopy (FT-IR), Differential Scanning Calorimetry (DSC), and Field Emission Scanning Electron Microscope (FE-SEM). Nitrogen adsorption measurements were done to determining the catalyst surface area and pore volume and pore size distribution. Also the acidity of catalysts was measured using NH3-TPD. The catalysts activity and product selectivity for ethylbenzene production have been investigated in a specially designed flow microreactor in gas phase. Effects of temperature and space velocity at constant benzene to ethanol ratio (3:1 volumetric ratio) have been studied for catalyst performance and ethylbenzene selectivity and yield. In comparison of two synthesized catalysts, MIL-88 showed a higher performance (100% ethanol conversion, 72% benzene conversion and 76% ethylbenzene selectivity at 175 °C). The main byproduct was recognized as toluene. Long reaction time for both catalysts showed no decline in conversion and selectivity of desired product. The BET measurement and the FTIR spectra of used catalysts revealed these Fe-based metal organic frameworks are stable catalysts for alkylation of benzene by ethanol.