Design of an acidic sulfonated mesoporous carbon catalyst for the synthesis of butyl levulinate from levulinic acid, B Bakhtiari, AN Chermahini, Z Babaei, Environmental Progress & Sustainable Energy, e13721 ,2021

In this work, the ordered mesoporous carbon CMK-8 which has some advantages, including large specific pore volume, high surface area, and also its tunable pore size, was synthesized, then functionalized with various sulfonic acid groups and utilized as a heterogeneous catalyst in the esterification reaction of levulinic acid (LA) into n-butyl levulinate (BL). The prepared catalysts were characterized using Fourier transformed-infrared spectroscopy, N₂ adsorption–desorption, small-angle X-ray diffraction analysis, elemental analysis, transmission electron microscopy, field emission scanning electron microscope, thermal gravimetric analysis, energy dispersive X-ray spectroscopy, and elemental mapping. The important parameters such as reaction temperature, reaction time, catalyst amount, and LA to n-BuOH molar ratio were investigated by Taguchi experimental design. Maximum BL yield (75.1%) and LA conversion (95%) were obtained with CMK-8-SO₃H catalyst under optimum reaction conditions: reaction temperature 130°C, reaction time 10 h, catalyst dosage 0.015 g, and LA to n-BuOH molar ratio 1:10. Among the entire parameters, LA to n-BuOH molar ratio followed by the reaction temperature, catalyst concentration, and reaction time have the most influence on BL yield. Finally, the regeneration and reusability of the CMK-8-SO₃H catalyst were studied, and the recovered catalyst showed high stability and activity after four runs.

https://aiche.onlinelibrary.wiley.com/doi/abs/10.1002/ep.13721