The organic modified montmorillonite was prepared by first and second intercalation modification of Na-montmorillonite

which was used to catalyze the reaction of technical grade oleic acid to prepare dimer acid

and the influence of the catalyst structure and composition on the catalytic performance was analyzed. All the samples were characterized by X-ray diffraction (XRD)

Fourier transform-infrared spectroscopy (FTIR)

scanning electron microscope (SEM)

transmission electron microscopy (TEM)

thermogravimetry (TG)

and dispersion experiments. The experimental results show that the layer spacing of modified montmorillonite is expanded from 1.48 nm to 3.82 nm

and the original sandwich structure remains unchanged. The surface morphology and internal structure of modified montmorillonite were changed

the surface became loose

the interlayer spacing was enlarged

and the content of intercalation agent was increased. The dispersion experiment showed that the montmorillonite had good dispersion performance in oleic acid after second modification. Under the same conditions

the second intercalation montmorillonite catalytic dimerization reaction of oleic acid

yield of dimer acid was 75.33%

which was 2.14 times higher than that of Na-MMT. Through FTIR

1H NMR and LC-MS showed that the synthesized product is dimer acid. Thus

it is evident that

the wider the interlayer spacing

the stronger the dispersion

and the better is the catalytic performance

this indicates that increasing the interlayer spacing and lipophilicity of MMT can promote the diffusion and adsorption of unsaturated fatty acids

thereby significantly increasing the yield of dimer acid.