Organic-inorganic hybrid supermicroporous iron(III) phosphonate nanoparticles as an efficient catalyst for the synthesis of biofuels

Article abstract of DOI:10.1002/chem.201300128

Here we report a novel family of crystalline, supermicroporous iron(III) phosphonate nanomaterials (HFeP-1-3, HFeP-1-2, and HFeP-1-4) with different Fe^III-to-organophosphonate ligand mole ratios. The materials were synthesized by using a hydrothermal reaction between benzene-1,3,5-triphosphonic acid and iron(III) chloride under acidic conditions (pH≈4.0). Powder X-ray diffraction, N₂ sorption, transmission and scanning electron microscopy (TEM and SEM) image analysis, thermogravimetric and differential thermal analysis (TGA-DTA), and FTIR spectroscopic tools were used to characterize the materials. The triclinic crystal phase [P1(2) space group] of the hybrid iron phosphonate was established by a Rietveld refinement of the PXRD analysis of HFeP-1-3 by using the MAUD program. The unit cell parameters are a=8.749(1), b=8.578(1), c=17.725(3) ?; α=104.47(3), β=97.64(1), γ=113.56(3)°; and V=1013.41 ?³. With these crystal parameters, we proposed an 24-membered-ring open framework structure for HFeP-1. Compound HFeP-1-3, with an starting Fe/ligand molar ratio of 3.0, shows the highest Brunauer-Emmett-Telller (BET) surface area of 556 m²g ^-1 and uniform supermicropores of approximately 1.1 nm. The acidic surface of the porous iron(III) phosphonate nanoparticles was used in a highly efficient and recyclable catalytic transesterification reaction for the synthesis of biofuels under mild reaction conditions. Iron brews biofuels: Highly crystalline, supermicroporous iron(III) phosphonate nanoparticles have been synthesized through a hydrothermal reaction between benzene-1,3,5- triphosphonic acid and FeCl₃. The resulting material was used as an efficient and recyclable catalyst for the synthesis of biofuels under mild reaction conditions (see scheme). Copyright