Because n‐butanol as a fuel additive has more advantageous physicochemical properties than those of ethanol, ethanol valorization to n‐butanol through homo‐ or heterogeneous catalysis has received much attention in recent decades in both scientific and industrial fields. Recent progress in catalyst development for upgrading ethanol to n‐butanol, which involves homogeneous catalysts, such as iridium and ruthenium complexes, and heterogeneous catalysts, including metal oxides, hydroxyapatite (HAP), and, in particular, supported metal catalysts, is reviewed herein. The structure–activity relationships of catalysts and underlying reaction mechanisms are critically examined, and future research directions on the design and improvement of catalysts are also proposed.

catalyst exhibited 49.8% of ethanol conversion, 48.6% of selectivity toward n-butanol, and thereby 24.2% of n-butanol yield at relatively low temperature (523 K) and pressure (2 MPa) during a 200 h long-term evaluation. The high catalytic activity and selectivity of Pd@UiO-66 catalyst are primarily ascribed to the close synergy of highly dispersed Pd nanoparticles and coordinatively unsaturated Zr sites on Zr 6 nodes of UiO-66, as active centers for dehydrogenation/hydrogenation and aldol condensation, respectively; however, the high stability of the catalyst is mainly attributed to the electrostatic attraction of Pd nanoparticles with Zr 6 nodes and the confinement effect of the cavities of UiO-66.

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Aldol condensation is a very useful reaction for biomass upgrading by coupling small molecule platform compounds into high value-added products. Here we choose acetaldehyde (AcH) condensation, the rate-determining step in bioethanol transformations, as a targeted reaction, and prepared four CeO 2 catalysts with different concentrations of surface oxygen vacancies to investigate the role of oxygen vacancies in this reaction. To the best of our knowledge, it is the first time to demonstrate that there is a linear correlation between the activity of aldol condensation and the concentration of oxygen vacancies. Based on in-situ FTIR studies, we conclude that oxygen vacancies are the Lewis acid sites for activation and stabilization of AcH, while lattice oxygen act as base sites for the formation of enolate species which are the key intermediates for AcH coupling reactions. Moreover, the proposed reaction mechanism indicates that Ce cations which are weak Lewis acid sites are not involved in the AcH condensation.

Direct conversion of methane to high valueadded oxygenates under mild conditions has attracted extensive interest. However, the over-oxidation of target products is usually unavoidable due to the easily excessive activation of CÀ H bond on the sites of supported metal species. Here, we identified the most efficient Zr-oxo nodes of UiO-66 metal-organic frameworks (MOFs) catalysts for the selective oxidation of methane with H 2 O 2 . These nodes were modified by three types of benzene 1, 4-dicarboxylates (NH 2 -BDC, H 2 BDC, and NO 2 -BDC). Detailed characterizations and DFT calculations revealed that these ligands can effectively tune the electronic properties of Zr-oxo nodes and the H 2 BDC ligand led to optimal electronic density of Zr-oxo nodes in UiO-66. Thus the UiO-66-H catalyst promoted the formation of * OH species that adsorbed on Zr-oxo nodes, and facilitated the activation of methane with a lower energy barrier and subsequent conversion to hydroxylation oxygenates with 100 % selectivity.