Strong Lewis Base Ga4B2O9: Ga-O Connectivity Enhanced Basicity and Its Applications in the Strecker Reaction and Catalytic Conversion of n-Propanol
Strong Lewis Base Ga4B2O9: Ga-O Connectivity Enhanced Basicity and Its Applications in the Strecker Reaction and Catalytic Conversion of n-Propanol
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强路易斯碱Ga4B2O9：Ga-O连通增强碱度及其在Strecker反应和正丙醇催化转化中的应用
DOI：
10.1021/acsami.8b04144
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发表时间：
2018
影响因子：
9.5
通讯作者：
Yang Tao
中科院分区：
文献类型：
--
作者：
Hu Shixiang;Wang Weilu;Yue Mufei;Wang Guangjia;Gao Wenliang;Cong Rihong;Yang Tao
非均相固体碱催化在化学工业中具有重要的应用价值和发展前景，但由于缺乏令人满意的固体碱催化剂，与固体酸催化相比，非均相固体碱催化发展不够。为了获得强碱性，以前的策略是用碱性金属将氧化物碱化以产生表面空位或缺陷，这在催化条件下存在不稳定性。像MgO这样的单组分碱性氧化物是稳定的，但缺乏吸电能力。本文证明了一种特殊的原子连通性可以提高单组分固体中氧的路易斯碱度，例如Ga4B2O9。结构诱导的碱度来自于μ3-O与五配位Ga3+的完全连接。在碱催化Strecker反应合成α-氨基腈过程中，Ga4B2O9的收率高达81%，是一种耐用的催化剂。此外，在streker反应中考察了几种单组分固体碱，其中Ga4B2O9具有最多的强碱中心（23.1 μmol/g）和最高的催化效率。a4B2O9也适用于高温固-气催化，例如，Ga4B2O9高效催化正丙醇脱氢，对丙醛有很高的选择性（79%）。而硼酸镓为Brönsted酸的Ga-PKU-1更倾向于催化脱水制得丙烯，其选择性为94%。
Heterogeneous solid base catalysis is valuable and promising in chemical industry, however it is insufficiently developed compared to solid acid catalysis due to the lack of satisfied solid base catalysts. To gain the strong basicity, the previous strategy was to basify oxides with alkaline metals to create surficial vacancies or defects, which suffers from the instability under catalytic conditions. Monocomponent basic oxides like MgO are literally stable but deficient in electronwithdrawing ability. Here we prove that a special connectivity of atoms could enhance the Lewis basicity of oxygen in monocomponent solids exemplified by Ga4B2O9. The structure-induced basicity is from the μ3-O linked exclusively to five-coordinated Ga3+. Ga4B2O9 behaved as a durable.catalyst with a high yield of 81% in the base-catalyzed synthesis of α-aminonitriles by Strecker reaction. In addition, several monocomponent solid bases were evaluated in the Strecker reaction, and Ga4B2O9 has the largest amount of strong base centers (23.1 μmol/g) and the highest catalytic efficiency. a4B2O9 is also applicable in hightemperature solid−gas catalysis, for example, Ga4B2O9 catalyzed efficiently the dehydrogenation of n-propanol, resulting in a high selectivity to propanal (79%). In contrast, the comparison gallium borate, Ga-PKU-1, which is a Brönsted acid, preferred to catalyze the dehydration process to obtain propylene with a selectivity of 94%.