Esterification of rapeseed oil fatty acids using a carbon-based heterogeneous acid catalyst derived from cellulose

• The conversion of cellulose into catalyst in presence of conc. H2SO4 reached ∼61%.
• High amounts of COOH, OH and SO3H sites have attached on obtained catalyst surface.
• Acidic sites increase hydrophilicity of catalyst surface and its catalytic performance.
• The conversion of rapeseed oil fatty acids over obtained catalyst reached 96.7%.
• The catalyst initial activity can be partially recovered by simple regeneration method.

The present work demonstrates a single-step preparation of sulfo carbon-based solid acid catalyst (CSO3H) obtained from cellulose by direct carbonization–sulfonation with conc. H2SO4. The variation of reaction conditions, such as, reaction temperature (50–180 °C), weight ratio of H2SO4 to cellulose (5/1–30/1) and reaction time (1–10 h) provided CSO3H with relatively abundant density of acid sites attached on catalyst surface. The CSO3H with the highest density of SO3H groups (0.81 mmol H+/g) was obtained at 100 °C using weight ratio of H2SO4 to cellulose (20/1) after 3 h of reaction. The catalyst was characterized by means of N2 sorption analysis (average pore diameter 12.8 nm, specific surface area 1.38 m2/g, pore volume 0.004 cm3/g), FT-IR, TG, XRD, FE-SEM and S elemental analysis. The conversion of rapeseed oil fatty acids (RFA) in esterification reactions with CSO3H as catalyst was quite similar to the commercial Amberlyst-15 and the biodiesel with ester content of ≥96.5% was successfully obtained under optimized reaction conditions.

Figure optionsDownload high-quality image (136 K)Download as PowerPoint slide