Energy transition, and the related chemistry transition due to their strong nexus, is creating a major worldwide change in the current production system, driven initially by social and environmental ...pressures (cleaner production, reduced greenhouse gas emissions), but today instead is pushed by economic (renewable energy sources are becoming progressively the more economic energy form) and geopolitical (energy security) motivations. Current process technologies in the area of chemical and fuel production cannot just be adapted, they need to be fully redesigned (also in terms of concepts, materials, engineering) to address the new challenges of using renewable energy sources in delocalized productions (small-scale production at the regional level using local resources and in strong symbiosis to other local productions). Rather than operations at high temperatures and sometimes also higher pressure, with heat as the main medium to provide/withdrawn energy to sustain the reaction, the use of renewable energy sources requires to change the catalytic technology, for example, using photons and/or electrons to drive the catalytic reactions, with operations typically at (or close to) ambient conditions. ...changing from thermal to photo/electrocatalysis requires a full rethinking of the conceptual aspects of catalyst design. 2 This opens new possibilities for the area of smart catalytic materials. ...by extending this concept, it is possible to consider photoelectron catalytic (PEC) devices able to operate directly in the sun-driven reduction of CO2 to chemicals/fuels capturing CO2 directly from the air, a giant step towards the uses of these devices for a sustainable future.
This review analyses the opportunities and prospects in the chemical recycling of carbon dioxide to fuels, as a complementary technology to carbon sequestration and storage (CSS). It is remarked that ...the requisites for this objective are (i) minimize as much as possible the consumption of hydrogen (or hydrogen sources), (ii) produce fuels that can be easily stored and transported, and (iii) use renewable energy sources. From this perspective, the preferable option is to produce alcohols (preferably ≥C2) using solar energy to produce the protons and electrons necessary for the reaction of CO
2 reduction. It is evidenced, however, that this is still a long-term objective, even if already some good advances in this direction exist. The different topics discussed in the review include CO
2 (i) reverse water–gas shift and (ii) hydrogenation to hydrocarbons, alcohols, dimethyl ether and formic acid, (iii) reaction with hydrocarbons to syngas, (iv) photo- and electrochemical/catalytic conversion, and (v) thermochemical conversion. Other relevant options, such as the use of micro-algae or other bio-catalysis based processes, or the use of microwave and plasma processes are instead not addressed. Therefore, the area of carbon dioxide conversion to fuels and chemicals is a very active R&D sector, and it is anticipated that it represents a challenging possibility for companies to develop complementary strategies to CSS to reduce greenhouse gas emissions.
The introduction of renewable energy in the chemical production chain is a key strategic factor both to realize a sustainable, resource‐efficient, low‐carbon economy and society and to drive ...innovation and competiveness in the chemical production. This Concept discusses this concept in terms of motivations, perspectives, and impact as well as technical barriers to achieve this goal. It is shown how an important element to realize this scenario is to foster the paths converting carbon dioxide (CO2) into feedstock for the chemical/process industry, which is one of the most efficient methods to rapidly introduce renewable energy into the chemical production chain. Some of the possible options to proceed in this direction are discussed, with focus on the technical barriers and enabling factors such as catalysis. The tight interconnection between CO2 management and the use of renewable energy is evidenced.
Measuring up: The introduction of renewable energy in the chemical production chain is a key strategic factor both to realize a sustainable, resource‐efficient, low‐carbon economy and society and to drive innovation and competiveness in the chemical production. Carbon dioxide (CO2) recycling is one possible option. This Concept discusses this concept in terms of motivations, perspectives, and impact as well as technical barriers to achieve this goal.
Ammonia is synthesized directly from water and N2 at room temperature and atmospheric pressure in a flow electrochemical cell operating in gas phase (half‐cell for the NH3 synthesis). Iron supported ...on carbon nanotubes (CNTs) was used as the electrocatalyst in this half‐cell. A rate of ammonia formation of 2.2×10−3 gNH3
m−2 h−1 was obtained at room temperature and atmospheric pressure in a flow of N2, with stable behavior for at least 60 h of reaction, under an applied potential of −2.0 V. This value is higher than the rate of ammonia formation obtained using noble metals (Ru/C) under comparable reaction conditions. Furthermore, hydrogen gas with a total Faraday efficiency as high as 95.1 % was obtained. Data also indicate that the active sites in NH3 electrocatalytic synthesis may be associated to specific carbon sites formed at the interface between iron particles and CNT and able to activate N2, making it more reactive towards hydrogenation.
Sustainable industrial chemistry: Ammonia is synthesized directly from water and N2 at room temperature and atmospheric pressure in an electrochemical flow cell operating in the gas phase (half‐cell for NH3 synthesis). Iron supported on carbon nanotubes was used as the electrocatalyst in this half‐cell.
There is increasing interest in plasma technology for CO2 conversion because it can operate at mild conditions and it can store fluctuating renewable electricity into value-added compounds and ...renewable fuels. This perspective paper aims to provide a view on the future for non-specialists who want to understand the role of plasma technology in the new scenario for sustainable and low-carbon energy and chemistry. Thus, it is prepared to give a personal view on future opportunities and challenges. First, we introduce the current state-of-the-art and the potential of plasma-based CO2 conversion. Subsequently, we discuss the challenges to overcome the current limitations and to apply plasma technology on a large scale. The final section discusses the general context and the potential benefits of plasma-based CO2 conversion for our life and the impact on climate change. It also includes a brief analysis on the future scenario for energy and chemical production, and how plasma technology may realize new paths for CO2 utilization.
Solar fuels from water and CO2 are a topic of current large scientific and industrial interest. Research advances on bioroutes, concentrated solar thermal and low‐temperature conversion using ...semiconductors and a photoelectrocatalytic (PEC) approach, are critically discussed and compared in an attempt to define challenges and current limits and to identify the priorities on which focus research and development (R&D). The need to produce fuels that are easy to transport and store, which can be integrated into the existing energy infrastructure, is emphasized. The role of solar fuels produced from CO2 in comparison with solar H2 is analyzed. Solar fuels are complementary to solar to electrical energy conversion, but they still need intensified R&D before possible commercialization.
State of the art research advances on bioroutes, concentrated solar thermal and low‐temperature conversion using semiconductors to produce solar fuels from water and CO2, are critically discussed in an attempt to define challenges and current limits and to identify the priorities on which focus research and development. The role of solar fuels produced from CO2 in comparison with solar H2 is analyzed and compared.
Nanocarbon materials play a critical role in the development of new or improved technologies and devices for sustainable production and use of renewable energy. This perspective paper defines some of ...the trends and outlooks in this exciting area, with the effort of evidencing some of the possibilities offered from the growing level of knowledge, as testified from the exponentially rising number of publications, and putting bases for a more rational design of these nanomaterials. The basic members of the new carbon family are fullerene, graphene, and carbon nanotube. Derived from them are carbon quantum dots, nanohorn, nanofiber, nano ribbon, nanocapsulate, nanocage and other nanomorphologies. Second generation nanocarbons are those which have been modified by surface functionalization or doping with heteroatoms to create specific tailored properties. The third generation of nanocarbons is the nanoarchitectured supramolecular hybrids or composites of the first and second genera- tion nanocarbons, or with organic or inorganic species. The advantages of the new carbon materials, relating to the field of sustainable energy, are discussed, evidencing the unique properties that they offer for developing next generation solar devices and energy storage solutions.
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