Dream Reaction Research Articles

Synthesis of acrylic acid and acrylates from CO<sub>2</sub> and ethylene — the thorny path from dream to reality

The development of atom-economical and efficient processes for obtaining a variety of chemical products using CO<sub>2</sub> as C<sub>1</sub>-synthon plays an increasingly important role in modern scientific and technological research. Due to the inertness of CO2 many extremely attractive routes to valuable chemical products turn out to be impossible to implement, particularly for thermodynamic reasons, leaving one only dreaming about them as something unattainable. This review demonstrates how the catalytic coupling of ethylene and CO<sub>2</sub> into acrylic acid, once considered a "dream reaction" has not only become a reality, but has also evolved into the category of technological processes. The key stages of the long-term development of this unique reaction from the discovery of metal activation of CO<sub>2</sub> and stoichiometric preparation of metallalactones to catalytic synthesis using a variety of metal-catalysts (Ni, Pd, Ru, Rh) showcase the ingenuity and skill of researchers as well as an example of consistent development in this field of chemistry. We believe that this remarkably successful example will inspire scientists to tackle any "impossible" problems.<br> The bibliography includes 117 references.

The fabrication of potassium ion modification on Cu2O(111) for enhanced propylene oxide selectivity: Insights from density functional theory

Utilizing the alkali metal effect to enhance catalyst performance is an effective approach in the development of highly efficient catalysts. Herein, we report a K+ ion-modification strategy on Cu-based catalysts for the direct epoxidation of propylene (DEP) using molecular oxygen, a reaction deemed as one of the “dream reactions” in heterogeneous catalysis. By elaborately engineering of K+-modified Cu2O(111) catalyst, we unveil the versatile roles played by K+ ions in promoting catalytic performance for DEP. Firstly, K+ ions stabilize the surface coordination structures of Cu2O(111). Secondly, K+ ions make the dissociation of adsorbed O2* less likely, thus facilitating the reaction of propylene with O2*. Furthermore, both K+ and two-coordinated Cu+ serve as active centers in this reaction. Lastly, K+ ions create unique surface coordination structures favorable for propylene oxide (PO) formation. The density functional theory (DFT) calculations demonstrate that the effective utilization of the alkali metal effect can engineer highly efficient Cu-based catalysts for DEP.

The formation of nickelalactone in CO2/C2H4 coupling reaction: A benchmark, dispersion correction, and energy decomposition analysis

The oxidative coupling of CO2 and ethylene for synthesizing acrylic acid and its derivatives is considered one of the “dream reactions” in catalysis. The formation of acrylic acid by CO2/C2H4 coupling is hardly possible due to the endothermic nature of the reaction. This work reports a comprehensive study of the nickelalactone formation from CO2/C2H4 coupling over Ni-catalysts. We have evaluated the accuracy of the DLPNO-CCSD(T) method in determining the barrier heights and the reaction energetics for the nickelalactone formation. Extrapolation to the complete basis set limit was performed using two-point extrapolation methods. It was found that the DLPNO-CCSD(T) method, in combination with the complete basis set cc-pVTZ/cc-pVQZ extrapolation, gives the error within 1.0 kcal/mol. To gain a molecular understanding of the formation of acrylic acid by CO2/C2H4 coupling, the distortion-interaction model was used as an energy decomposition method to analyze the inner- and outer-sphere reaction transition states, considering two competing pathways. It was found that i) the inner-sphere reaction is superior to the outer-sphere reaction owing to the lower distortion energy and stronger interactions, ii) three prominent pairs of orbital interactions exist between the Ni-C2H4 complex and the CO2 molecule, and iii) the dispersion correction is crucial to obtaining reliable non-covalent interaction energies.

Can we achieve efficient photocatalytic partial oxidation of methane to methanol: A perspective on oxygen reaction pathways

As the primary component of natural gas, methane is an essential raw material in chemical industries. Meanwhile, it is also a powerful greenhouse gas that causes severe global warming effects. On-site conversion of methane to value-added chemicals and fuels, especially transportable and storable methanol, is a dream reaction. However, traditional methane oxidation methods will consume huge amounts of energy and lead to carbon emission. Utilizing only renewable solar energy, photocatalysis has attracted increasing interest for methane oxidation to methanol due to its low energy consumption and environmental friendliness. In this work, a perspective on photocatalytic methane oxidation to methanol is proposed by analyzing the oxygen source of methanol, which can be a new strategy to modulate the methane oxidation reaction. It provides a new angle to understand the mechanism of the reaction, and inspirations for optimizing the efficiency and selectivity of methanol production from photocatalytic methane oxidation.

Young German Catalysis Society ‐ YounGeCatS

Young, creative, connecting.1 As the youth organization of the GeCatS (German Catalysis Society), we are focusing on the field of catalysis, where we facilitate intensive exchange and discussion between our members and within the scientific community. That is why we offer a variety of platforms for a successful exchange: An important event are our annual network meetings, where we visit chemical companies in Germany such as Covestro, Clariant and many more. In addition, the network meetings also offer time and space to connect as well as to personally develop oneself in the frame of soft skill workshops, e.g., design of posters and talks along with their presentation. Every 2nd year, we also offer Summer Schools on exciting topics in catalysis such as “Shaping a green future” or “Dream reactions”. We partly organize them in cooperation with the young reaction engineers, the NaWuReTs to foster an interdisciplinary exchange among chemists and engineers. The participating PhD students and postdocs approach the topic by lectures and group sessions and have plenty of opportunity to socialize, for example while enjoying a dinner together. By contributing actively to the program, we also help to make the annual GeCatS meeting in Weimar a success. We work closely together with GeCatS and the Dechema e.V. to make this event a yearly highlight in the schedule of German catalysis researchers. Here we organize poster sessions, which give PhD students the opportunity to showcase their research in short presentations. The best contributions are honored with a poster award. Furthermore, we promote the collaboration of young scientists from industry and academia by organizing an informal social event in a local pub. At our career forum, there is also the opportunity to meet potential employers and find out about job opportunities. Young European Catalysis Society - YounGeCatS Founded: 2012 Organizationteam: Anna Katharina Beine, Rene Eckert, Tanja Franken, Pawel Naliwajko, Juliane Titus, Clara Watermann, Sebastian Weber Homepage: http://gecats.org/YounGeCatS.html Contact: [email protected] Twitter: @youngecats We have now presented our organization quite sufficiently and would prefer to give space to the opinions of our members: Unfortunately, I don′t remember any specific experience of the network meetings in particular, but I found the general format very nice and I remember it well overall. The combination of scientific lectures, personal development, visits and insights into exciting companies and get-togethers is, in my view, a very exciting format. Whether this took place in Hanau, Munich, Leipzig or Rosenheim - it was always a successful event. On the way to my current position, YounGeCatS helped me only indirectly through the collection of experience and insights into different areas and companies. However, the contacts I made in YounGeCatS still help me now to find the right contacts for various questions and thus to be able to solve scientific problems together. As a doctoral student, I participated in conferences alone, i.e., without other colleagues from my institute. It was always nice to know that many familiar faces were represented there, whom you got to know through the YounGeCatS network meetings. This way, a good scientific exchange could always take place. In addition, the contacts made in this way can also lead to good collaborations beyond the doctoral period. I have always enjoyed the selection, organization and implementation of the poster workshops in particular. I think that it is a great exercise for the presenters and that those present are more likely to dare to actively participate in the discussion in a small group. As I was one of the founding members of YounGeCatS, I have a lot of great memories of our activities of the first five years. Especially our planning meetings in advance to any events were very intense and quite rememberable. One of the greatest memories are associated actually with our first “official” meeting in a bar directly after the initial assembly of the first organization team. We exchanged first ideas and collected our mobile numbers on a beer coaster – I keep the copy till today. Take every networking meeting, exchange ideas and most of all: have fun. YounGeCatS is open to all interested young scientists in the field of catalysis. If you do not want to miss any update follow us on social media (LinkedIn & Twitter) or become part of our mailing list (just write an E-Mail to “[email protected]”)

The mechanism of visible light-induced C-C cross-coupling by Csp3-H bond activation.

Csp3-C cross-coupling by activating Csp3-H bonds is a dream reaction for the chemical community, and visible light-induced transition metal-catalysis under mild reaction conditions is considered a powerful tool to achieve it. Advancement of this research area is still in its infancy because of the chemical and technical complexity of this catalysis. Mechanistic studies illuminating the operative reaction pathways can rationalize the increasing amount of experimental catalysis data and provide the knowledge allowing faster and rational advances in the field. This goal requires complementary experimental and theoretical mechanistic studies, as each of them is unfit to clarify the operative mechanisms alone. In this tutorial review we summarize representative experimental and computational mechanistic studies, highlighting weaknesses, strengths, and synergies between the two approaches.

Copper-zeolites Prepared by Solid-state Ion Exchange - Characterization and Evaluation for the Direct Conversion of Methane to Methanol

AbstractDirect conversion of methane to methanol (MTM) over Cu-zeolites is a so-called “dream reaction” for the chemical industry. There is still a lot that can be done in order to optimize the reaction by e.g. achieving a deeper understanding of the reaction mechanism and the nature of the Cu-sites. In this study, we investigated a solid-state ion exchange method to incorporate CuI ions into zeolites (MOR, BEA, ZSM-5 and FAU), as a more scalable technique. The solid-state ion exchange led to a Cu/Al ration of about 0.8, however with a heterogeneous distribution of Cu. Regardless, Fourier transform-infrared spectroscopy still revealed that most Brønsted acid sites were exchanged in all four samples. Further, CH4-temperature programmed reaction experiments showed that some Cu-sites formed were reactive towards CH4, with CuI-MOR and CuI-FAU having the largest CH4 consumption. Ultimately, the CuI-zeolites were tested in the MTM reaction and proved capable of producing methanol, even without the presence of Brønsted sites. A MOR with lower Cu/Al ratio (0.30) was also tested for comparison, and as this sample obtained a much higher productivity than the CuI-MOR with high Cu-loading (0.10 vs. 0.03 molMeOH/molCu), it was demonstrated that some fine-tuning is necessary to obtain the active Cu sites for methane activation.

Catalytic direct hydrocarboxylation of styrenes with CO2 and H2.

A three-component hydrocarboxylation of an olefin with CO2 and H2 could be regarded as a dream reaction, since it would provide a straightforward approach for the synthesis of aliphatic carboxylic acids in perfect atom economy. However, this transformation has not been realized in a direct manner under mild conditions, because boosting the carboxylation with thermodynamically stable CO2 while suppressing the rapid hydrogenation of olefin remains a challenging task. Here, we report a rhodium-catalysed reductive hydrocarboxylation of styrene derivatives with CO2 and H2 under mild conditions, in which H2 served as the terminal reductant. In this approach, the carboxylation process was largely accelerated by visible light irradiation, which was proved both experimentally and by computational studies. Hydrocarboxylation of various kinds of styrene derivatives was achieved in good yields without additional base under ambient pressure of CO2/H2 at room temperature. Mechanistic investigations revealed that use of a cationic rhodium complex was critical to achieve high hydrocarboxylation selectivity.

Mechanistic insights into propylene oxidation to acrolein over gold catalysts

Direct epoxidation of propylene with H2/O2, being the dream reaction for propylene oxide (PO) production, has raised wide scientific and industrial interests. Fundamentally understanding the formation mechanism of acrolein, as the main by-product of this epoxidation process, is very important to achieve the high yield of PO. In this study, we perform the spin-polarized density functional theory (DFT) calculations to investigate the reaction pathway from propylene to acrolein over two representative Au surfaces, that is, Au(1 1 1) and Au(1 0 0), which incorporates propylene adsorption, methyl hydrogen activation and acrolein formation. The results show that the oxygenated species (mainly O*, OH* and OOH*) are able to stabilize the adsorption of propylene to decrease the energy barrier for its activation. It is demonstrated that the OOH* on Au(1 1 1) surface emerges as the most easily formed oxygenated species via the H-assisted O2 dissociation, which is also the most active for the cleavage of methyl CH bond in propylene. Furthermore, three pathways of acrolein formation activated by O*/OH*/OOH* are analyzed, in which O* is found as the key species to form acrolein. Finally, Bader charge analysis was conducted to explore the reasons behind the promotion effect of the oxygenated species. The insights reported here could be valuable in the design and optimization of gold catalysts for the direct epoxidation of propylene.

Non‐oxidative Dehydrogenation of Methanol to Formaldehyde over Bulk β‐Ga2O3

AbstractThe non‐oxidative dehydrogenation of methanol to formaldehyde is considered a dream reaction compared with the classical oxidative route, because the valuable coupled product hydrogen is formed instead of water, and the produced anhydrous formaldehyde is highly suitable for the further synthesis of oxygenated synthetic fuels. This study reports on the high catalytic performance of pure β‐Ga2O3 in this reaction at temperatures between 500 °C and 650 °C. At 550 °C and a GHSV of 45500 h−1, an initial selectivity to formaldehyde of 77 % was obtained at a methanol conversion of 72 %. Performing the reaction at temperatures beyond this range and lower GHSV resulted in a lower formaldehyde selectivity. The catalyst suffered from deactivation caused by formation of carbon deposits, but it was possible to regenerate its initial activity at 500 °C and 550 °C completely by an oxidative treatment. Irreversible deactivation occurred at 650 °C due to partial volatilization of Ga2O3.

Direct Propylene Epoxidation with Molecular Oxygen over Cobalt-Containing Zeolites.

Direct propylene epoxidation with molecular oxygen is a dream reaction with 100% atom economy, but aerobic epoxidation is challenging because of the undesired over-oxidation and isomerization of epoxide products. Herein, we report the construction of uniform cobalt ions confined in faujasite zeolite, namely, Co@Y, which exhibits unprecedented catalytic performance in the aerobic epoxidation of propylene. Propylene conversion of 24.6% is achieved at propylene oxide selectivity of 57% at 773 K, giving a state-of-the-art propylene oxide production rate of 4.7 mmol/gcat/h. The catalytic performance of Co@Y is very stable, and no activity loss can be observed for over 200 h. Spectroscopic analyses reveal the details of molecular oxygen activation on isolated cobalt ions, followed by interaction with propylene to produce epoxide, in which the Co2+-Coδ+-Co2+ (2 < δ < 3) redox cycle is involved. The reaction pathway of propylene oxide and byproduct acrolein formation from propylene epoxidation is investigated by density functional theory calculations, and the unique catalytic performance of Co@Y is interpreted. This work presents an explicit example of constructing specific transition-metal ions within the zeolite matrix toward selective catalytic oxidations.

Bioinspired Trinuclear Copper Catalyst for Water Oxidation with a Turnover Frequency up to 20000 s-1.

Solar-powered water splitting is a dream reaction for constructing an artificial photosynthetic system for producing solar fuels. Natural photosystem II is a prototype template for research on artificial solar energy conversion by oxidizing water into molecular oxygen and supplying four electrons for fuel production. Although a range of synthetic molecular water oxidation catalysts have been developed, the understanding of O-O bond formation in this multielectron and multiproton catalytic process is limited, and thus water oxidation is still a big challenge. Herein, we report a trinuclear copper cluster that displays outstanding reactivity toward catalytic water oxidation inspired by multicopper oxidases (MCOs), which provides efficient catalytic four-electron reduction of O2 to water. This synthetic mimic exhibits a turnover frequency of 20000 s-1 in sodium bicarbonate solution, which is about 150 and 15 times higher than that of the mononuclear Cu catalyst (F-N2O2Cu, 131.6 s-1) and binuclear Cu2 complex (HappCu2, 1375 s-1), respectively. This work shows that the cooperation between multiple metals is an effective strategy to regulate the formation of O-O bond in water oxidation catalysis.

Plasma assisted CO2 splitting to carbon and oxygen: A concept review analysis

This concept review paper analyses the possibility to develop a technical solution for the challenging reaction of CO2 splitting to carbon and O2 (CO2tC). This is a dream reaction in the area of addressing climate change and greenhouse gas emissions. There are quite limited literature indications that were reviewed, with an analysis also of the limits and perspectives. Not-thermal plasma, in combination with catalysis, is one of the possibilities to promote this reaction. Current studies on plasma-assisted CO2 splitting are limited mainly to the formation of CO. By combining data on the status of current studies on plasma CO2 splitting with those on CO2tC it is possible to propose a tentative novel approach. This is a conceptual idea presented and discussed as vehicle to stimulate research in the area, including proposing alternative possibilities. The challenges of this concept and reaction are discussed.

Methane oxidation to methanol over copper-containing zeolite

Methane oxidation to methanol over copper-containing zeolite

Recent Advances in Photocatalytic Transformation of Carbohydrates Into Valuable Platform Chemicals

In response to the less accessible fossil resources and deteriorating environmental problems, catalytic conversion of the abundant and renewable lignocellulosic biomass to replace fossil resources for the production of value-added chemicals and fuels is of great importance. Depolymerization of carbohydrate and its derivatives can obtain a series of C5-C6 monosaccharides (e.g., glucose and xylose) and their derived platform compounds (e.g., HMF and furfural). Selective transformation of lignocellulose using sustainable solar energy via photocatalysis has attract broad interest from a growing scientific community. The unique photogenerated reactive species (e.g., h+, e−, •OH, •O2−, and 1O2), novel reaction pathways as well as the mild reaction conditions make photocatalysis a “dream reaction.” This review is aimed to provide an overview of the up-to-date contributions achieved in the selective photocatalytic transformation of carbohydrate and its derivatives. Photocatalytic methods, properties and merits of different catalytic systems are well summarized. We then put forward future perspective and challenges in this field.

Water-involved methane-selective catalytic oxidation by dioxygen over copper zeolites

Summary The selective oxidation of methane to methanol is a dream reaction of direct methane functionalization, which remains a key challenge in catalysis and a hot topic of controversy. Herein, we report the water-involved methane-selective catalytic oxidation by dioxygen over copper zeolites. At 573 K, a state-of-the-art methanol space-time yield of 543 mmol/molCu/h with methanol selectivity of 91% is achieved with a Cu–CHA catalyst. Temperature-programmed surface reactions with isotope labeling suggest water as the apparent oxygen and hydrogen source of hydroxyl in methanol. Spectroscopic analyses reveal the fast redox cycle of Cu2+-Cu+-Cu2+ during methane-selective oxidation, which is closely related to the high catalytic activity of Cu–CHA. Density functional theory calculations suggest that both CuOH monomer and dimer in Cu–CHA can catalyze the selective oxidation of methane to methanol with Cu–OOH as the key reaction intermediate, and meanwhile, various copper sites may undergo interconversion under reaction conditions.

Continuous Synthesis of Methanol from Methane and Steam over Copper-Mordenite

One-step methane-to-methanol conversion is a “dream reaction” for chemists. In this Letter, continuous direct conversion of methane into methanol with steam under mild conditions using Cu(II)-excha...

Green synthesized cobalt-bipyridine constructed conjugated microporous polymer: An efficient heterogeneous catalyst for cycloaddition of epoxides via CO2 fixation under ambient conditions

Abstract The conversion of carbon dioxide into valuable cyclic carbonates has been of intensive interest owing to the 100% atomic economy. Conjugated microporous polymers (CMPs) are attractive porous materials contain organic functionalities for applications in gas capture, energy storage, and catalysis. Herein, we developed a new synthesis method of CMP, obtained at room temperature which is one of the “dream reaction”, possessing large surface areas (1356 m2/g) and exhibiting excellent CO2 capture (77.26 cm3/g at 273.15 K/1.00 bar). After loading cobalt acetate, we obtained Co-coordinated CMP (named as TBB-BPY-Co), exhibiting extraordinary activities (turnover frequencies of up to 250 h-1) for the coupling epoxides with CO2 forming cyclic carbonates at room temperature and atmospheric with free-solvent. Moreover, the heterogeneous catalyst showed even better catalytic efficiency than relevant homogeneous catalyst and a higher recyclability (up to 10 times). This study provided an effective and efficient strategy for the carbon dioxide conversion of industrial and economic value.

Selective Photo-oxidation of Methane to Methanol with Oxygen over Dual-Cocatalyst-Modified Titanium Dioxide

Direct and selective oxidation of CH4 with dioxygen to methanol is a “dream reaction” in modern catalysis yet remains a great challenge. Here, we report that TiO2 loaded with dual cocatalysts, that...

Critical Roles of Doping Cl on Cu2O Nanocrystals for Direct Epoxidation of Propylene by Molecular Oxygen.

Direct epoxidation of propylene by molecular oxygen alone is one of the "dream reactions" in heterogeneous catalysis. Despite much effort, the yield of propylene epoxide is still too low to be commercially attractive due to the trade-off between conversion and selectivity. Here, we demonstrate that doping Cl into the lattice of Cu2O nanocrystals by the intergrowth method not only can enhance the catalytic selectivity and conversion of direct propylene epoxidation but also can solve the long-existing Cl loss problem. In particular, Cl-doped rhombic dodecahedral Cu2O with (110) exposing facets exhibited 63% PO selectivity with a 12.0 h-1 turnover frequency at 200 °C, outperforming any other coinage metal-based catalysts under mild conditions. Comprehensive characterization and theoretical calculations revealed that the Cl-decorated Cu(I) facilitated formation of electrophilic oxygen species, thus boosting the production of propylene oxide. This work provides a general strategy to develop catalysts and explore the promoter effect by creating uniform isolated anion doping to activate a nearby metal center by virtue of well-defined nanocrystals.