Adsorptive removal of nitrogen-containing compounds from fuel by metal-organic frameworks

The adsorptive denitrogenation from fuels over three metal-organic frameworks(MIL-96(Al),MIL-53(Al)and MIL-101(Cr))was studied by batch adsorption experiments.Four nitrogen-containing compounds(NCCs)pyridine,pyrrole,quinoline and indole were used as model NCCs in fuels to study the adsorption mechanism.The physicochemical properties of the adsorbents were characterized by XRD,N2physical adsorption,FT-IR spectrum and Hammett indicator method.The metal-organic frameworks(MOFs),especially the MIL-101(Cr)containing Lewis acid sites as well as high specific surface area,can adsorb large quantities of NCCs from fuels.In addition,the adsorptive capacity over MIL-101(Cr)will be different for NCCs with different basicity.The stronger basicity of the NCC is,the more it can be absorbed over MIL-101(Cr).Furthermore,pore size and shape also affect the adsorption capacity for a given adsorbate,which can be proved by the adsorption over MIL-53(Al)and MIL-96(Al).The pseudo-second-order kinetic model and Langmuir equation can be used to describe kinetics and thermodynamics of the adsorption process,respectively.Finally,the regeneration of the used adsorbent has been conducted successfully by just washing it with ethanol.

Multi-response optimization of MIL-101 synthesis for selectively adsorbing N-compounds from fuels

In this work,MIL-101,a metal organic framework,has been synthesized and examined in the adsorptive denitrogenation process.Due to the importance of adsorption capacity and selectivity,the effects of synthesis parameters including metal type,reagent ratio,time and temperature on the MIL-101 performance were investigated by measuring quinoline(QUI)separation from iso-octane.The optimum conditions were determined using a Taguchi experimental design and the multiresponse optimization(multivariate statistical)method.Based on the arithmetic mean of normalized QUI adsorption capacity and QUI/dibenzothiophene(DBT)selectivity,as the objective function,the optimum value of synthesis parameters were found to be manganese as metal type in the structure,180°C for synthesis temperature,15h for synthesis time and 1.00 for reagent molar ratio.Under these conditions,QUI adsorption capacity and QUI/DBT selectivity were 19.3 mg-N/g-Ads.and 24.6,respectively.Accordingly,the arithmetic mean between normalized values of these measured parameters was equal to 1.10,which is in good agreement with the predicted value.The MIL-101 produced under optimum conditions was characterized by determining its specific surface area,X-ray powder diffraction patterns and Fourier transform infrared spectroscopy.Finally,isotherm and kinetic studies indicate that the Langmuir isotherm and pseudo-first-order model can successfully describe the experimental data.