Liquid Organic Hydrogen Carriers (LOHCs) as H‐Source for Bio‐Derived Fuels and Additives Production

Abstract

consumption combined with a resource efficient circular economy approach, with the final goal of minimizing the impact of health, safety, security and environment.In the design of a greener future, the replacement of depleting sources with renewable ones is at the center of a sustainable development. [2] Biomass is a natural, abundant, renewable, carbon-neutral source; its use represents a promising strategy to address the need for substituting fossil feedstock in the preparation of chemicals, fuels, and materials, besides energy production. [3][4][5][6][7][8][9][10][11][12][13][14] The major issues that limit the large-scale utilization of biomass in fuel production are the differences in cost and process efficiencies compared to those for fossil fuels. [15] After the Covid-19 crisis, this aspect has become even more evident, as reported by the International Agency of Energy, ultimately causing the first contraction in biofuel production over the past two decades. [16] The reduced transport fuel demand and the decreased petroleum-based fuel prices have transitorily lowered the economic interest for biofuel production. In this pandemic and emergency scenario, therefore, has emerged even more clearly the importance of developing efficient strategies for biomass conversion into fuels, making economically attractive the use of environmentally friendly renewable energy systems (Figure 1). [17] Among the plethora of biomass transformations, hydrogenation and hydrodeoxygenation reactions are widely used for decreasing the oxygen content of biomass-derived platforms to increase their potential as fuels. [18][19][20] In this context, as well as in the challenging goal of creating a decarbonized energy system, hydrogen plays a prominent role in the chemical industry. [21][22][23][24] It is important to notice that the vast majority of the worldwide hydrogen production (45-65 Mt/year) features a significant CO 2 footprint as a consequence of different hydrocarbon reforming processes (i.e., steam-reforming of fossil fuels, thermal cracking of natural gas, solar-thermal reforming of methane) or of coal gasification. [25] Several efforts have been directed during the past years toward the definition of possible effective approaches to a green H 2 production by water splitting. [26][27][28][29][30][31] To date, however, both water electrolysis and photo-driven water splitting are economically and energetically unfavorable, with a long way ahead to hold the promise of a zero-carbon energy system. Indeed, the associated energy demand as well as the low market prices of oxygen, inevitably co-produced from water electrolysis, hinder the shaping of a large-scale employment of this technology.Liquid organic hydrogen carriers (LOHCs) are attractive materials for their ability to generate in situ hydrogen that may be directly used to produce target biofuel precursors, fuels or fuel additives. Indeed, the replacement of fossil feedstock is an urgent necessity for shifting toward a carbon neutral energy economy. Several desired chemica...

Formic Acid Dehydrogenation over Ru- and Pd-Based Catalysts: Gas- vs. Liquid-Phase Reactions

“…Among the main solutions to hydrogen transport and storage issues, liquid organic hydrogen carriers (LOHCs) have emerged as one of the most promising and attractive materials for hydrogen storage since they are compounds that are able to capture and release hydrogen through chemical reactions. Their ability to generate in situ hydrogen in conjunction with their high gravimetric storage density (2–4 kWh kg −1 ) as compared to metal hydrides (<1 kWh kg −1 ) or compressed hydrogen gas (2 kWh kg −1 ) has converted these materials into a safer option for energy storage via hydrogen [ 3 , 4 ]. Furthermore, the current crude-oil-based infrastructure could serve for the implementation of LOHCs since they are liquid at ambient conditions and present properties similar to those of traditional liquid oils [ 3 ].…”

Catalytic Dehydrogenation of Liquid Organic Hydrogen Carrier Model Compounds by CpM+ (M = Fe, Co, Ni) in the Gas Phase

“…A key requirement of these LOHC systems is the need for dehydrogenation catalysts to liberate hydrogen on demand, and much work has been carried out to develop both homogeneous and heterogeneous catalysts. ,− While heterogeneous catalysts seem to hold most promise for large-scale dehydrogenation, the use of homogeneous catalysts offers advantages in studying reaction mechanisms and characterizing reactive intermediates. Multiple groups have investigated molecular catalysts involving the dehydrogenation of not only homocyclic compounds, but also N-heterocycles.…”

Anisole hydrodeoxygenation over Ni–Co bimetallic catalyst: a combination of experimental, kinetic and DFT study

“…2 Conventional hydrogen and liquid organic hydrogen carriers (LOHCs) can be used for HDO. 3 However, noble metal catalysts, high temperature and uncontrolled HDO limit the use of LOHCs for low cost selective production of cyclic alcohol. 4–6…”

“…2 Conventional hydrogen and liquid organic hydrogen carriers (LOHCs) can be used for HDO. 3 However, noble metal catalysts, high temperature and uncontrolled HDO limit the use of LOHCs for low cost selective production of cyclic alcohol. [4][5][6] Non-noble metal-based catalytic systems with high hydrogenation capability and controlled deoxygenation are critical for developing an efficient process.…”

“…[7][8][9][10] Literature reports suggest that the combination of Ni with transition metals such as Fe, Mo, Co, and Cu is more active and selective for HDO under ambient reaction conditions. 3,4 Therefore, numerous bimetallic catalysts Ni-Co, Ni-Fe, Ni-Cu, and Ni-Mo have been used for HDO. It was found that Ni-Mo and Ni-Fe based catalysts are suitable for the production of aromatic compounds.…”