Homogeneous Catalysis for Sustainable Hydrogen Storage in Formic Acid and Alcohols

Abstract

Hydrogen gas is a storable form of chemical energy that could complement intermittent renewable energy conversion. One of the main disadvantages of hydrogen gas arises from its low density, and therefore, efficient handling and storage methods are key factors that need to be addressed to realize a hydrogen-based economy. Storage systems based on liquids, in particular, formic acid and alcohols, are highly attractive hydrogen carriers as they can be made from CO or other renewable materials, they can be used in stationary power storage units such as hydrogen filling stations, and they can be used directly as transportation fuels. However, to bring about a paradigm change in our energy infrastructure, efficient catalytic processes that release the hydrogen from these molecules, as well as catalysts that regenerate these molecules from CO and hydrogen, are required. In this review, we describe the considerable progress that has been made in homogeneous catalysis for these critical reactions, namely, the hydrogenation of CO to formic acid and methanol and the reverse dehydrogenation reactions. The dehydrogenation of higher alcohols available from renewable feedstocks is also described. Key structural features of the catalysts are analyzed, as is the role of additives, which are required in many systems. Particular attention is paid to advances in sustainable catalytic processes, especially to additive-free processes and catalysts based on Earth-abundant metal ions. Mechanistic information is also presented, and it is hoped that this review not only provides an account of the state of the art in the field but also offers insights into how superior catalytic systems can be obtained in the future.

Fabrication of a Spherical Superstructure of Carbon Nanorods

“…[16,22,[25][26][27][28][29] Herein, we fabricate a spherical superstructure of carbon nanorods (SS-CNR), for the first time, by the self-templated thermal transformation of a spherical superstructure of MOF nanorods (SS-MOFNR). [31] The synthetic approach for SS-CNR is shown in Figure 1. The obtained SS-CNR with preserved superstructure can be used as an excellent support for immobilizing ultrafine Pd nanoparticles (NPs), which show an exceptionally high activity for hydrogen evolution from formic acid (FA) that has been considered a safe and promising hydrogen carrier.…”

Hidrogén tárolása homogén katalitikus kémiai rendszerekben

“…platform vegyület, amelynek bázisán az ipar a jelenleg fosszilis szénhidrogén alapon elõállított vegyületek, anyagféleségek sokaságát gyártaná. Ugyancsak a metanol lehetne a legszélesebb körben használt motorhajtó anyag, ideális esetben közvetlenül metanollal mûködõ tüzelõanyag elemben 8 oxidálva vízzé és szén-dioxiddá. Ha a metanolt légköri szén-dioxid hidrogénezésével állítják elõ (1. egyenlet), aminek üzemanyagként történõ elégetése során ekvimoláris mennyiségû CO 2 keletkezik, akkor a körfolyamat révén formálisan nem kerül többlet szén-dioxid a levegõbe.…”

Formation of metallacarboxylic acids through Hieber base reaction. A density functional theory study

“…Development of homogeneous transition metal catalysts for H 2 production from methanol [11, 12] has attracted much attention in the past few decades. Morton and Cole-Hamilton developed a ruthenium catalyst [Ru(H) 2 (X 2 )(PPh 3 ) 3 ] (X = N, H) for partial dehydrogenation of alcohols (including methanol) with notable turnover frequencies [13].…”