Starting with coal, followed by petroleum oil and natural gas, the utilization of fossil fuels has allowed the fast and unprecedented development of human society. However, the burning of these ...resources in ever increasing pace is accompanied by large amounts of anthropogenic CO
2
emissions, which are outpacing the natural carbon cycle, causing adverse global environmental changes, the full extent of which is still unclear. Even through fossil fuels are still abundant, they are nevertheless limited and will, in time, be depleted. Chemical recycling of CO
2
to renewable fuels and materials, primarily methanol, offers a powerful alternative to tackle both issues, that is, global climate change and fossil fuel depletion. The energy needed for the reduction of CO
2
can come from any renewable energy source such as solar and wind. Methanol, the simplest C
1
liquid product that can be easily obtained from any carbon source, including biomass and CO
2
, has been proposed as a key component of such an anthropogenic carbon cycle in the framework of a "Methanol Economy". Methanol itself is an excellent fuel for internal combustion engines, fuel cells, stoves,
etc.
It's dehydration product, dimethyl ether, is a diesel fuel and liquefied petroleum gas (LPG) substitute. Furthermore, methanol can be transformed to ethylene, propylene and most of the petrochemical products currently obtained from fossil fuels. The conversion of CO
2
to methanol is discussed in detail in this review.
Possible pathways to recycle CO
2
to methanol, dimethyl ether and derived products in a sustainable anthropogenic carbon cycle are discussed.
Easy to prepare solid materials based on fumed silica impregnated with polyethylenimine (PEI) were found to be superior adsorbents for the capture of carbon dioxide directly from air. During the ...initial hours of the experiments, these adsorbents effectively scrubbed all the CO2 from the air despite its very low concentration. The effect of moisture on the adsorption characteristics and capacity was studied at room temperature. Regenerative ability was also determined in a short series of adsorption/desorption cycles.
Adsorbents prepared easily by impregnation of fumed silica with polyethylenimine (PEI) are promising candidates for the capture of CO2 directly from the air. These inexpensive adsorbents have high ...CO2 adsorption capacity at ambient temperature and can be regenerated in repeated cycles under mild conditions. Despite the very low CO2 concentration, they are able to scrub efficiently all CO2 out of the air in the initial hours of the experiments. The influence of parameters such as PEI loading, adsorption and desorption temperature, particle size, and PEI molecular weight on the adsorption behavior were investigated. The mild regeneration temperatures required could allow the use of waste heat available in many industrial processes as well as solar heat. CO2 adsorption from the air has a number of applications. Removal of CO2 from a closed environment, such as a submarine or space vehicles, is essential for life support. The supply of CO2‐free air is also critical for alkaline fuel cells and batteries. Direct air capture of CO2 could also help mitigate the rising concerns about atmospheric CO2 concentration and associated climatic changes, while, at the same time, provide the first step for an anthropogenic carbon cycle.
As easy as breathing: Materials prepared from widely available fumed silica and polyethylenimines are used as efficient and inexpensive adsorbents for the capture of CO2 directly from the air (see picture). They can be easily regenerated under mild conditions for numerous adsorption/desorption cycles.
Due to the intermittent nature of most renewable energy sources, such as solar and wind, energy storage is increasingly required. Since electricity is difficult to store, hydrogen obtained by ...electrochemical water splitting has been proposed as an energy carrier. However, the handling and transportation of hydrogen in large quantities is in itself a challenge. We therefore present here a method for hydrogen storage based on a CO2(HCO3−)/H2 and formate equilibrium. This amine‐free and efficient reversible system (>90 % yield in both directions) is catalyzed by well‐defined and commercially available Ru pincer complexes. The formate dehydrogenation was triggered by simple pressure swing without requiring external pH control or the change of either the solvent or the catalyst. Up to six hydrogenation–dehydrogenation cycles were performed and the catalyst performance remained steady with high selectivity (CO free H2/CO2 mixture was produced).
Carbon‐neutral cycle! A practical, reversible, and amine‐free hydrogen‐storage system using Ru‐pincer catalyst is presented here. At high H2 pressure, hydrogen combined with CO2 (HCO3−) is stored in the form of formate salts. At low pressure, H2 is released. Up to six hydrogenation–dehydrogenation cycles were performed and the catalyst performance remained steady with high selectivity.
This study represents a notable step toward a potentially carbon neutral energy storage solution based on formic acid as a hydrogen/energy carrier. A catalytic system derived from IrCl3 and ...1,3-bis(2′-pyridyl-imino)-isoindoline (IndH) in the presence of aqueous sodium formate showed high selectivity and robustness for hydrogen generation from formic acid (FA) at 90–100 °C under both high and moderate pressure conditions suppressing the formation of CO impurity. Being a solid substance, the catalyst can be recovered by a simple filtration, if necessary. Furthermore, addition of neat formic acid is sufficient to reuse the catalyst and maintain a constant flow of H2 and CO2 mixture and the stable performance of a coupled fuel cell. The easy to recycle catalyst did not show any loss of activity after 20 days of continuous use, and similar activity was observed even a year after the original preparation. The reactor for formic acid decomposition provided a one to one ratio of a H2/CO2 mixture that was coupled to a hydrogen/air proton exchange membrane (PEM) fuel cell to demonstrate a stable and continuous conversion of chemical energy to electricity. This integrated system embodies the first example of an indirect formic acid fuel cell, which can function, without the requirement of applying inert conditions and feed gas purification, for extended periods of time.
The present Minireview covers the formation and the structural characterization of noble metal carbonyl and hydrido carbonyl complexes, with particular emphasis on ruthenium complexes using formic ...acid as a carbonyl and hydride source. The catalytic activity of these organometallic compounds for the decarboxylation of formic acid, a potential hydrogen storage material, is also reviewed. In addition, the first preparation of Ru4(CO)12H4 from RuCl3 and formic acid as well as the catalytic activity of Ru4(CO)12H4 for the decomposition of formic acid to hydrogen and carbon dioxide are presented.
Renewable energy carrier: Carbonylation and hydrido carbonylation of ruthenium halides by formic acid is reviewed. The first preparation of Ru4(CO)12H4, using formic acid as the exclusive CO and hydride source, and the catalytic activity of Ru4(CO)12H4 for the decomposition of formic acid to CO2 and H2 are also reported.
Formic acid is decomposed to H2 and CO2 in the presence of RuCl3 and triphenylphosphines in an emulsion. In situ formed ruthenium carbonyls, such as Ru(HCO2)2(CO)2(PPh3)2 (1), Ru(CO)3(PPh3)2 (2), and ...Ru2(HCO2)2(CO)4(PPh3)2 (3), and a large cluster, involving a Ru12 core, were identified and structurally characterized from the reaction mixtures. The catalytic activity of the mono and binuclear complexes was also investigated and it was found that Ru2(HCO2)2(CO)4(PPh3)2 (3) shows high stability even at elevated temperatures and pressures and its activity is 1 order of magnitude lower than those measured for the mononuclear complexes. It was also attempted to use Ru(HCO2)2(CO)2(PPh3)2 (1) as a catalyst for the hydrogenation of CO2 to formic acid under neutral conditions. Although the reduction of CO2 did not take place, the conversion of Ru(HCO2)2(CO)2(PPh3)2 (1) to an unexpected carbonate, Ru(CO3)(CO)2(PPh3)2·H2O was observed.
The monomer N′‐octadecyl‐Nα‐(4‐vinyl)‐benzoyl‐L‐phenylalanineamide (4) based on L‐phenylalanine has been simply but effectively synthesized, and its self‐assembling properties have been investigated. ...FTIR and a variable‐temperature 1H NMR spectroscopic investigation demonstrated that the aggregation of compound 4 in various organic solvents is due to the formation of intermolecular hydrogen bonds among the amide moieties. UV/Vis measurements indicated that the multiple π–π interactions of the phenyl groups also contribute to the self‐assembly. As was observed by 13C cross‐polarization magic‐angle spinning (CP/MAS) NMR and variable‐temperature 1H NMR measurements, the ordered alkyl chains also played an important role in the molecular aggregation by van der Waals interactions. Compound 4 was polymerized by surface‐initiated atom transfer radical polymerization from porous silica gel to prepare a packing material for HPLC. The results of thermogravimetric analysis showed that a relatively large amount of polymer was grafted onto the silica surface. The organic phase on silica was in a noncrystalline solid form in which the long alkyl chain exists in a less‐ordered gauche conformation. Analysis of chromatographic performance for polyaromatic hydrocarbon samples showed higher selectivity than conventional reversed‐phase HPLC packing materials.
Pack it in: An L‐phenylalanine‐based vinylic monomer (1) self‐assembles by hydrogen bonding. Its surface‐initiated radical polymerization can be carried out from silica particles to produce a stationary phase (Sil‐poly1) for HPLC applications. The chromatographic performance of Sil‐poly1 for polyaromatic hydrocarbons (PAHs; see figure) shows higher selectivity than conventional reversed‐phase HPLC packing materials.
