脱水Ni-Fe类水滑石的制备及其作为环保型催化剂用于生物质糠醛的高选择性缩醛化反应

合成了含硝酸根离子的脱水Ni-Fe类水滑石（Ni-Fe HTLCs）并将其应用于室温下的糠醛缩醛化反应。脱水Ni-Fe HTLCs对糠醛缩醛化反应显示出高选择性并基本实现糠醛的完全转化。作为耐水的路易斯酸和脱水剂，脱水Ni-Fe HTLCs被证明是适用于糠醛缩醛化反应的高效双功能催化剂。通过研究发现，脱除Ni-Fe HTLCs中水分导致颗粒收缩并增强层板间硝酸根离子间的电荷互斥，Ni-Fe HTLCs中弱酸性位点在糠醛缩醛化中发挥重要作用，脱水可改变酸性位点结构并增强其活性。脱水Ni-Fe HTLCs可吸收缩醛化反应中产生的大部分水分，但吸水后Ni-Fe HTLCs的结构并不能完全恢复，这可能是由扩散进入HTLCs层板间的有机分子导致。

Preparation of Dehydrated Ni-Fe Hydrotalcite-like Compounds as an Eco-Friendly Catalyst for Highly Selective Acetalization of Biomass-Derived Furfural

The dehydrated Ni-Fe hydrotalcite-like compounds (Ni-Fe HTLCs) containing nitrate anions were synthesized and applied in furfural acetalization at room temperature. The dehydrated Ni-Fe HTLCs showed good selectivity for furfural acetalization and achieved almost complete conversion of furfural. The dehydrated Ni-Fe HTLCs as water-tolerant Lewis acids and water scavengers was proved to be an efficient bifunctional catalyst for furfural acetalization. The removal of interlayer water leads to shrinkage of Ni-Fe HTLCs particles and increase in electronic repulsion among NO₃^- ions in the interlayer. The weak acid sites in Ni-Fe HTLCs play an important role in furfural acetalization. The dehydration changes structure of the acid sites and thus improves activity of the weak acid sites. The dehydrated Ni-Fe HTLCs can absorb the most of the resulting water during furfural acetalization, but the structure of Ni-Fe HTLCs cannot completely recover after rehydration possibly due to hindering effect of organic molecules diffusing into interlayer space.