How green was my valley: Green carbon science focuses on the transformations of carbon‐containing compounds in the entire carbon cycle. The ultimate aim is to use carbon resources efficiently and ...minimize the net CO2 emission. This holistic view also has ramifications for related fields including petroleum refining and the production of liquid fuels and chemicals from coal, methane, CO2, and biomass.
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► Progress on CO2 capture, storage, and utilization (CCSU) in Chinese Academy of Sciences (CAS) were reviewed. ► The main advantages and disadvantages of the CCSU process were ...discussed. ► The further research directions of CCSU were proposed.
This article reviews the progress made in CO2 capture, storage, and utilization in Chinese Academy of Sciences (CAS). New concepts such as adsorption using dry regenerable solid sorbents as well as functional ionic liquids (ILs) for CO2 capture are thoroughly discussed. Carbon sequestration, such as geological sequestration, mineral carbonation and ocean storage are also covered. The utilization of CO2 as a raw material in the synthesis of chemicals and liquid energy carriers which offers a way to mitigate the increasing CO2 buildup is introduced.
CO2 electroreduction is a promising technique for satisfying both renewable energy storage and a negative carbon cycle. However, it remains a challenge to convert CO2 into C2 products with high ...efficiency and selectivity. Herein, we report a nitrogen‐doped ordered cylindrical mesoporous carbon as a robust metal‐free catalyst for CO2 electroreduction, enabling the efficient production of ethanol with nearly 100 % selectivity and high faradaic efficiency of 77 % at −0.56 V versus the reversible hydrogen electrode. Experiments and density functional theory calculations demonstrate that the synergetic effect of the nitrogen heteroatoms and the cylindrical channel configurations facilitate the dimerization of key CO* intermediates and the subsequent proton–electron transfers, resulting in superior electrocatalytic performance for synthesizing ethanol from CO2.
Favoring flat drinks: Ethanol was synthesized by CO2 electroreduction over a nitrogen‐doped ordered cylindrical mesoporous carbon. Almost 100 % selectivity toward ethanol with a high faradaic efficiency of 77 % at −0.56 V vs. RHE was achieved, which was attributed to the synergetic effect of the nitrogen heteroatoms and the cylindrical channel configurations.
Plant rejuvenation refers to the reversal of the adult phase in plants and the recovery of part or all of juvenile plant characteristics. The growth and reproductive vitality of plants can be ...increased after rejuvenation. In recent years, research has successfully reversed the development clock in plants by certain methods; created rejuvenated plants and revealed the basic rules of plant morphology, physiology and reproduction. Here, we reconstitute the changes at the morphological and macromolecular levels, including those in RNA, phytohormones and DNA, during plant rejuvenation. In addition, the characteristics of plant phase changes that can be used as references for plant rejuvenation are also summarized. We further propose possible mechanisms for plant rejuvenation, methods for reversing plant development and problems that should be avoided. Overall, this study highlights the physiological and molecular events involved in plant rejuvenation.
Carbon dioxide (CO2) hydrogenation to liquid fuels including gasoline, jet fuel, diesel, methanol, ethanol, and other higher alcohols via heterogeneous catalysis, using renewable energy, not only ...effectively alleviates environmental problems caused by massive CO2 emissions, but also reduces our excessive dependence on fossil fuels. In this Outlook, we review the latest development in the design of novel and very promising heterogeneous catalysts for direct CO2 hydrogenation to methanol, liquid hydrocarbons, and higher alcohols. Compared with methanol production, the synthesis of products with two or more carbons (C2+) faces greater challenges. Highly efficient synthesis of C2+ products from CO2 hydrogenation can be achieved by a reaction coupling strategy that first converts CO2 to carbon monoxide or methanol and then conducts a C–C coupling reaction over a bifunctional/multifunctional catalyst. Apart from the catalytic performance, unique catalyst design ideas, and structure–performance relationship, we also discuss current challenges in catalyst development and perspectives for industrial applications.
Conversion of carbon dioxide (CO2) into fuels and chemicals by electroreduction has attracted significant interest, although it suffers from a large overpotential and low selectivity. A Pd‐Sn alloy ...electrocatalyst was developed for the exclusive conversion of CO2 into formic acid in an aqueous solution. This catalyst showed a nearly perfect faradaic efficiency toward formic acid formation at the very low overpotential of −0.26 V, where both CO formation and hydrogen evolution were completely suppressed. Density functional theory (DFT) calculations suggested that the formation of the key reaction intermediate HCOO* as well as the product formic acid was the most favorable over the Pd‐Sn alloy catalyst surface with an atomic composition of PdSnO2, consistent with experiments.
The right mix: Pd‐Sn alloy supported electrocatalysts were synthesized for the electrochemical conversion of CO2 in an aqueous solution. A nearly perfect faradaic efficiency toward formic acid formation at a very low overpotential of −0.26 V was achieved over PdSn/C, which was attributed to the optimal surface oxide configuration.
Using hydrocarbons as reagents
Adding small alkyl groups to complex molecules usually relies on alkyl halide reagents. Laudadio
et al.
now report a convenient method to add ethane and propane ...directly across conjugated olefins with no prefunctionalization or byproducts (see the Perspective by Oksdath-Mansilla). The C–H bond scission in this hydroalkylation is accomplished by a decatungstate photocatalyst that also acts as a hydrogen atom transfer agent to complete the process. The reaction, optimized under flow conditions, works with methane as well, albeit with lower efficiency.
Science
, this issue p.
92
; see also p.
34
A photocatalytic method adds saturated hydrocarbons across conjugated olefins with no by-products.
Direct activation of gaseous hydrocarbons remains a major challenge for the chemistry community. Because of the intrinsic inertness of these compounds, harsh reaction conditions are typically required to enable C(sp
3
)–H bond cleavage, barring potential applications in synthetic organic chemistry. Here, we report a general and mild strategy to activate C(sp
3
)–H bonds in methane, ethane, propane, and isobutane through hydrogen atom transfer using inexpensive decatungstate as photocatalyst at room temperature. The corresponding carbon-centered radicals can be effectively trapped by a variety of Michael acceptors, leading to the corresponding hydroalkylated adducts in good isolated yields and high selectivity (38 examples).
Lower olefins-generally referring to ethylene, propylene and butylene-are basic carbon-based building blocks that are widely used in the chemical industry, and are traditionally produced through ...thermal or catalytic cracking of a range of hydrocarbon feedstocks, such as naphtha, gas oil, condensates and light alkanes. With the rapid depletion of the limited petroleum reserves that serve as the source of these hydrocarbons, there is an urgent need for processes that can produce lower olefins from alternative feedstocks. The 'Fischer-Tropsch to olefins' (FTO) process has long offered a way of producing lower olefins directly from syngas-a mixture of hydrogen and carbon monoxide that is readily derived from coal, biomass and natural gas. But the hydrocarbons obtained with the FTO process typically follow the so-called Anderson-Schulz-Flory distribution, which is characterized by a maximum C
-C
hydrocarbon fraction of about 56.7 per cent and an undesired methane fraction of about 29.2 per cent (refs 1, 10, 11, 12). Here we show that, under mild reaction conditions, cobalt carbide quadrangular nanoprisms catalyse the FTO conversion of syngas with high selectivity for the production of lower olefins (constituting around 60.8 per cent of the carbon products), while generating little methane (about 5.0 per cent), with the ratio of desired unsaturated hydrocarbons to less valuable saturated hydrocarbons amongst the C
-C
products being as high as 30. Detailed catalyst characterization during the initial reaction stage and theoretical calculations indicate that preferentially exposed {101} and {020} facets play a pivotal role during syngas conversion, in that they favour olefin production and inhibit methane formation, and thereby render cobalt carbide nanoprisms a promising new catalyst system for directly converting syngas into lower olefins.
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•In-Zr/SAPO-34 catalysts were used for direct CO2 hydrogenation to lower olefins.•In-Zr composite oxides were prepared with the introduction of different Zr content.•A selectivity for ...C2=–C4= was up to 80% in hydrocarbons with 2% CH4 and 64% CO.•The addition of a certain amount of Zr can markedly enhance catalytic performance.
Direct production of lower olefins (C2=−C4=: ethylene, propylene and butylene), basic carbon-based building blocks, from carbon dioxide (CO2) hydrogenation is highly attractive, although the selectivity towards olefins has been too low. Here we present a series of bifunctional catalysts contained indium-zirconium composite oxides with different In:Zr atomic ratios and SAPO-34 zeolite, which can achieve a selectivity for C2=–C4= as high as 65–80% and that for C2–C4 of 96% with only about 2.5% methane among the hydrocarbon products at CO2 conversion of 15–27%. The selectivity of CO via the reverse water gas shift reaction is lower than 70%. The product distribution is completely different from that obtained via CO2-based Fischer-Tropsch synthesis and deviates greatly from the classical Anderson-Schulz-Flory distribution. The zirconium component plays a critical role in determining the physicochemical properties and catalytic performance of bifunctional catalysts. Catalyst characterization and density functional theory calculations demonstrate that the incorporation of a certain amount of zirconium can create more oxygen vacancy sites, stabilize the intermediates in CO2 hydrogenation and prevent the sintering of the active nanoparticles, thus leading to significantly enhanced catalytic activity, selectivity of hydrocarbons and stability for direct CO2 hydrogenation to lower olefins at the relatively high reaction temperature of 380 °C.
Conversion of carbon dioxide (CO2) to fuels and chemicals with the help of renewable hydrogen (H2) is a very attractive approach to reduce CO2 emissions and replace dwindling fossil fuels. However, ...it is still a great challenge to synthesize aromatics directly from CO2 hydrogenation, because CO2 is thermodynamically very stable, and the aromatics are highly unsaturated products with complex structures. Here, we demonstrate that the combination of the sodium-modified spinel oxide ZnFeO x , which alone shows excellent performance for CO2 hydrogenation to olefins, and hierarchical nanocrystalline HZSM-5 aggregates can realize a highly efficient synthesis of aromatics directly from CO2 and H2. The maximum of aromatics selectivity was up to 75.6% among all hydrocarbons at 41.2% CO2 conversion. Additionally, the selectivity toward CO and CH4 is usually less than 20% over this catalyst system. The suitable amount of the residual sodium, hierarchical pore structure, and appropriate density of Brønsted acid sites endow the composite catalyst with an outstanding aromatics yield and high catalytic stability.
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