Supported catalysts based on layered double hydroxides for catalytic oxidation and hydrogenation: general functionality and promising application prospects

Abstract

Oxidation and hydrogenation catalysis plays a crucial role in the current chemical industry for the production of key chemicals and intermediates. Because of their easy separation and recyclability, supported catalysts are widely used in these two processes. Layered double hydroxides (LDHs) with the advantages of unique structure, composition diversity, high stability, ease of preparation and low cost have shown great potential in the design and synthesis of novel supported catalysts. This review summarizes the recent progress in supported catalysts by using LDHs as supports/precursors for catalytic oxidation and hydrogenation. Particularly, partial hydrogenation of acetylene, hydrogenation of dimethyl terephthalate, methanation, epoxidation of olefins, elimination of NOx and SOx emissions, and selective oxidation of biomass have been chosen as representative reactions in the petrochemical, fine chemicals, environmental protection and clean energy fields to highlight the potential application and the general functionality of LDH-based catalysts in catalytic oxidation and hydrogenation. Finally, we concisely discuss some of the scientific challenges and opportunities of supported catalysts based on LDH materials.

Recent advances on the utilization of layered double hydroxides (LDHs) and related heterogeneous catalysts in a lignocellulosic-feedstock biorefinery scheme

“…Although the relationship between the structural and catalytic properties of these types of materials has been widely covered in several literature revisions, 11,20,24,[27][28][29][30] this section highlights the importance of the LDH structure for the design of highly active and stable heterogeneous catalysts to be implemented in a biorefinery process.…”

“…Au, Ni, Ru, Pd). 20 Additionally, the uniform distribution of the M 2+ and M 3+ cations in the layered structure makes these materials excellent precursors for the preparation of highly dispersed metal-supported catalysts. [52][53][54][55][56][57] This preparation approach requires the introduction of the catalytically active species as substituted cations in the structure of the LDHs during the synthesis, followed by calcination and reduction steps.…”

“…In a recent literature revision, Li et al 20 summarized several advantages of the utilization of LDHs in the field of heterogeneous catalysis. From those advantages, we have selected three properties as the most relevant ones for the design of solid catalysts for biorefinery processes: (i) cation-tunability of the brucite-like layers and anionic exchangeability, which provides to the LDHs-derived catalysts a wide versatility in composition; 26,32 (ii) tunable basicity of the surface in both, nature (Brønsted and Lewis type basic sites) and strength (from weak-middle to strong basic sites); 28,33 and (iii) uniform dispersion of M 2+ and M 3+ cations in the layers, as well as preferred orientation of anions in the interlayer, allowing the formation of highly dispersed and stable metal supported catalysts.…”

“…[11][12][13][14] These types of heterogeneous catalysts are already playing a relevant role in several biomass valorization processes (including lignocellulosic biomass), as can be seen from the numerous scientific reports and literature revisions dedicated to this topic. [15][16][17][18][19][20][21][22][23] Nonetheless, most of the reviews currently available in the literature are focused on the utilization and potential of inorganic metal oxides (either pure or mixed metal oxides) and zeolites for biomass transformation (and derived platform molecules), and less attention has been given to LDH-type and derived catalysts.…”

Layered Double Hydroxide Nanostructured Photocatalysts for Renewable Energy Production

“…[ 19,22,23 ] Li et al reviewed the synthesis of LDHs, their transformation to mixed metal oxides by thermal treatment and/or reduction, and also their applications to heterogeneous catalysts. [24][25][26] The fabrication and applications of LDH-based nanocomposites represent an important new direction in the development of multifunctional materials, [ 20,[27][28][29] with the obtained nanocomposites exhibiting enormous promise in are divalent and trivalent cations, and A is the interlayer anion ( Figure 2 ). However, LDH materials can also accommodate cations in other valence states, including Li + , Sn 4+ or Ti 4+ , and have been widely studied as adsorbents and as catalyst supports due to the tunability of their compositions and morphologies.…”