K2CO3-loaded hydrotalcite: A promising heterogeneous solid base catalyst for biolubricant base oil production from waste cooking oils

- Comprehensive study on HT/K2CO3 catalyst for biolubricant base oil production.
- Both catalyst preparation and transesterification conditions were optimized.
- Metal ion leaching was significantly reduced by optimal HT/K2CO3 catalyst.
- Reactivation methods were firstly investigated for the optimal catalyst recycling.
- The catalyst performance, quality and function mechanism were elaborated.

Hydrotalcite (HT) loaded with potassium carbonate (K2CO3) was originally applied as a promising heterogeneous solid base catalyst for the production of trimethylolpropane fatty acid triester (TFATE) as the biolubricant base oil through transesterification of fatty acid methyl esters (FAME) from waste cooking oils and trimethylolpropane (TMP), in which FAME to TMP ratio (3:1), catalyst dosage (2% w/w), pressure (300 Pa), temperature (160 °C) and time (2 h) were optimized in order to obtain the best TFATE yield (80.6%). Based on the above, K2CO3 dosage (30% w/w) and calcination temperature (500 °C) in the preparation of HT/K2CO3 catalyst were optimized to improve the TFATE yield to 93.9% along with 97.7% of conversion rate of FAME (CRF). The catalyst recycling was also investigated to determine the suitable reactivated method. Besides, HT/K2CO3 catalysts in various states were characterized for better comprehension of their functional mechanisms and appropriate potential applications.

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