Catalytic upgrading of ethanol to n-butanol over a novel Ca-Fe modified mixed oxide Mg-Al catalyst from hydrotalcite-base precursor
Catalytic upgrading of ethanol to n-butanol over a novel Ca-Fe modified mixed oxide Mg-Al catalyst from hydrotalcite-base precursor
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DOI：
10.1016/j.cattod.2021.07.029
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发表时间：
2022-06-07
期刊：
影响因子：
5.3
通讯作者：
Alemany, L. J.
中科院分区：
文献类型：
--
作者：
Molina-Ramirez, S.;Cortes-Reyes, M.;Alemany, L. J.
正丁醇具有广泛的应用，最近，已经提出使用正丁醇作为燃料，其可以单独使用或与汽油或柴油混合使用。因此，为了深化从乙醇生产正丁醇的一步催化过程，开发、制备和表征了不同化学/空间环境下的双功能催化剂，如MgAl-和CaFeMg-多氧化物催化剂。考虑到Mg2+和Al3+被Ca2+和Fe3+部分取代，通过热分解合成的水滑石得到两种混合氧化物，即MgAl-Ox和Ca20Fe20MgAl-Ox。使用 NH3 和 CO2 作为探针分子分析样品的酸性质和碱性质，并进行 TPD 分析以量化酸/碱位点的相对贡献。 Ca20Fe20MgAl-Ox 样品的碱度有所改善，酸度降低幅度最小。通过 DRIFT-MS 研究和瞬态脉冲实验，在固定床反应器中在瞬态和连续操作模式下测量了活化催化剂的性能。经证实，两种催化剂，特别是Ca20Fe20MgAl-Ox，由于调节的酸和碱位点能够以乙氧基形式改变乙醇吸附，并且结合较高的碱度与中心以乙醇作为氢供体催化加氢，因此促进从乙醇合成C-4-化合物。 Ca20Fe20MgAl-Ox 在 280 ℃ 时乙醇转化率达到 36%，在 400 ℃ 时乙醇转化率达到 71%，对正丁醇和其他 C-4 化合物具有更高的选择性。不同温度下的两个平行静音：直接乙醛自缩合和中间巴豆醇转移氢化，在正丁醇形成中得到证实并普遍存在。
n-Butanol is used in a wide range of applications and recently, the use of n-butanol as a fuel, which can be employed pure or blended with gasoline or diesel, has been proposed. So, in an attempt to deepen in the one-step catalytic process to produce n-butanol from ethanol, bifunctional catalysts in different chemical/spatial environment as MgAl- and CaFeMg-multioxide catalysts were developed, prepared and characterized. Both mixed oxides were obtained by thermal decomposition of the synthesized hydrotalcites considering the partial substitution of Mg2+ and Al3+ by Ca2+ and Fe3+, namely MgAl-Ox and Ca20Fe20MgAl-Ox. The nature of acid and basic properties of the samples were analyzed employing NH3 and CO2 as probe molecules, and TPD analysis were performed to quantify the relative contribution of acidic/basic sites. Ca20Fe20MgAl-Ox sample presented an improved basicity with minimal acidity reduction. The performances of the activated catalysts were measured in a fixed-bed reactor under transient and continuous operation modes by DRIFT-MS studies and under transient pulse experiments. It was verified that both catalysts, but specially Ca20Fe20MgAl-Ox, promote the synthesis of C-4-compounds from ethanol due to the modulated acid and basic sites capable of modify the ethanol adsorption in the form of ethoxy-species and a combined higher basicity with centers to catalyze the hydrogenation using the ethanol as the hydrogen donor. Ca20Fe20MgAl-Ox reached ethanol conversion values of 36% at 280 degrees C and 71% at 400 degrees C with a higher selectivity to n-butanol and other C-4-compounds. Two parallel mutes at differentiated temperatures: direct acetaldehyde self-condensation and the intermediary crotyl alcohol transfer hydrogenation, were evidenced and prevailing in n-butanol formation.