Synthesis p-menthane-3,8-diol over sustainable acid carbon catalysts derived from alkaline lignin

摘要

p-Menthane-3,8-diol (PMD) is a compound that has been receiving growing attention as a natural insect repellent, which has lower toxicity than widely used N,N-diethyl m-toluamide (DEET). 1 In this study, sustainable acid carbon catalysts derived from alkaline lignin (AL) were prepared for synthesizing PMD from a widely available chemical of (±)-citronellal (Scheme 1). The effect of pyrolysis temperature of AL toward the acid properties of the carbon catalysts was also investigated. The catalytic performances of the AL-based carbon acid catalysts were higher than those standard catalyst materials such as carbon black and H-USY. Especially, when AL was pyrolyzed at 400 °C, the obtained catalyst showed high conversion of citronellal (96 %) and high yield of PMD product (79 %). This study shows a new perspective to utilize wasted alkaline lignin as a source of acid catalysts.