循環農業：農業廢棄物高價值化【環境工程學系/林坤儀特聘教授】
| 論文篇名 | 英文：TEMPO-Functionalized Silica as an Efficient and Recyclable Oxidation Catalyst for Conversion of a Lignin Model Compound to Value-Added Products 中文：TEMPO功能化二氧化矽作為將木質素模型化合物轉化為增值產品的高效可循環氧化催化劑 |
| 期刊名稱 | WASTE AND BIOMASS VALORIZATION |
| 發表年份,卷數,起迄頁數 | 2019, in press |
| 作者 | Zheng, Meng‑Wei; Lin, Kun‑Yi Andrew(林坤儀)*; Lin, Chia‑Hua* |
| DOI | 10.1007/s12649-019-00910-8 |
| 中文摘要 | 木質素模型化合物香草醇（VAL）的催化氧化為香草醛（VN）是增值木質素基生物質的一種有前途的方法。由於對醇氧化的研究興趣集中在直接使用O2上，因此已開發出2,2,6,6-四甲基哌啶1-氧基（TEMPO）作為氧化催化劑，可以由O2介導以循環氧化醇。但是，由於從反應介質中回收均相TEMPO可能是一個問題，因此有必要開發一種可回收的異質TEMPO用於VAL氧化。在本研究中，通過將OH-TEMPO和原矽酸四乙酯簡單縮合以將TEMPO官能團插入SiO2基質中，可以製造出特定的異質TEMPO。然後將所得的TEMPO @ SiO2複合材料首次用於將VAL氧化為VN。通過與助催化劑Cu 結合，TEMPO @ SiO2 / Cu 成功地將VAL選擇性地轉化為VN，相應的轉化效率達到CVAL = 96％，SVN = 96.5，YVN = 92.6％。在環境溫度下30分鐘內可以方便地獲得如此優異的轉化效率，這表明TEMPO @ SiO2不僅是高活性催化劑，而且還是可持續的氧化催化劑。 TEMPO @ SiO2 / Cu 的最佳條件是7.5 g / L TEMPO @ SiO2和5 g / L銅鹽。 TEMPO @ SiO2還可以在多個循環中重複使用，以將VAL轉換為VN，並且對VN的選擇性穩定。這些特徵證明，TEMPO @ SiO2確實是一種有前途的，高選擇性和高效的非均相催化劑，可將木質素模型化合物VAL增值至目標產品VN。 |
| 英文摘要 | Catalytic oxidation of a lignin model compound, vanillyl alcohol (VAL), to vanillin (VN), is a promising process for valorizing lignin-based biomass. As research interests in oxidation of alcohols are concentrated on direct usage of O2, 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO) has been developed as an oxidation catalyst which can be mediated by O2 to cyclically oxidize alcohols. However, as recover of homogeneous TEMPO from reaction media could be an issue, it is necessary to develop a recyclable heterogeneous TEMPO for VAL oxidation. In the present study, a particular heterogeneous TEMPO is fabricated via a simple condensation of OH-TEMPO and tetraethyl orthosilicate to insert TEMPO functional groups into SiO2 matrices. The resulting composite of TEMPO@SiO2 is then employed for the first time for oxidation of VAL to VN. By incorporation with a co-catalyst, Cu , TEMPO@SiO2/Cu successfully and selectively converts VAL to VN, and the corresponding conversion efficiency reaches CVAL = 96% with SVN = 96.5 and YVN = 92.6%. Such a superior conversion efficiency is achieved conveniently at ambient temperature within 30 min, demonstrating that TEMPO@SiO2 is not only a highly active catalyst but also a sustainable oxidation catalyst. The optimum condition of TEMPO@SiO2/Cu is 7.5 g/L of TEMPO@SiO2 and 5 g/L of Cu salt. TEMPO@SiO2 can be also reused over multiple cycles for VAL conversion to VN with a stably high selectivity for VN. These features validate that TEMPO@SiO2 is indeed a promising, highly-selective and efficient heterogeneous catalyst for valorization of VAL, the lignin model compound, to the target product, VN. |
