Selective oxidation of benzene to phenol using functionalized membrane via Fenton-like process

Abstract

This study investigates direct conversion of benzene to phenol in liquid phase using catalytic membrane reactor. Functionalized membranes were prepared and utilized to introduce a novel method for one-step hydroxylation of benzene. Non-solvent induced phase separation (NIPS) technique was employed to prepare asymmetric poly(vinylidene fluoride) (PVDF) membranes with finger-like structure. The prepared membranes were modified by surface dehydrofluorination technique as a chemical treatment prior to catalyst loading. Iron oxide nanoparticles, as catalyst, were integrated into the membrane pores functionalized with poly(acrylic acid) (PAA) for prevention of leaching and agglomeration. Formation of CC conjugated double bonds through the chemical treatment and grafting of PAA were approved by attenuated total reflectance fourier transform infrared spectroscopy (ATR-FTIR). The loading content of the catalyst was evaluated by energy-dispersive X-ray spectroscopy (EDS) and inductively coupled plasma-atomic emission spectrometry (ICP-AES) analyses. Additionally, structural properties of the membranes such as morphology, mechanical strength, hydrophobicity-hydrophilicity, pore size and porosity were studied.We investigated influence of different parameters such as catalyst loading content, contact time of feed and catalyst, and reaction temperature on the selectivity and yield of phenol. Promising results were obtained. For instance, phenol yield of 6.22% and phenol selectivity of 100% were achieved at contact time of 1 s, reaction temperature of 45 °C, trans-membrane pressure (TMP) of 0.4 bar, and membrane cross-flow rate of 439 L/m2.hr. The catalyst loading content was equal to 25.5 w% of the catalytic membrane.