An investigation of the catalytic decomposition of formic acid on raw and manganese oxide coated sepiolite surfaces

In this study, a mild chemical method was developed to synthesize manganese oxide coated sepiolite from RS, Mn(NO3)2 and H2O2 in an alkaline solution at room temperature. The samples were characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), infrared (IR) and thermal analysis (TA). After heating up to 600 °C, the structure of the γ-MnO2 phase gradually transformed into the Mn2O3 phase. TA indicated the transformation of γ-MnO2 into Mn2O3 between 400 and 600 °C. IR spectra of manganese oxides showed signature bands between 400 and 650 cm− 1 due to Mn–O lattice vibrations. The thermal desorption of pyridine was followed by IR and TA techniques to estimate the acidity of the samples. Decomposition of formic acid over RS and MCS was studied by IR spectroscopy at 100–400 °C. Monodentate symmetric and asymmetric formates were observed after formic acid adsorption between 100 and 300 °C.

► Sepiolite coated with MnO2 was tested as catalyst for formic acid decomposition.
► The decomposition of formic acid with the coated sepiolite is superior to the raw sepiolite.
► The coated sepiolite displayed higher adsorption of formic acid than raw sepiolite.