Surface science approach to the heterogeneous cycloaddition of CO2 to epoxides catalyzed by site-isolated metal complexes and single atoms: a review

Green Chemical Engineering, Journal Year: 2022, Volume and Issue: 3(3), P. 210 - 227

Published: Feb. 5, 2022

The cycloaddition of CO2 to epoxides afford cyclic organic carbonates is an increasingly relevant non-reductive strategy convert useful products able serve as high-boiling solvents, chemical intermediates, and monomers for the preparation more sustainable polymers. development efficient robust heterogeneous catalysts such transformation is, therefore, crucial can be carried out by several strategies that often require sophisticated and/or expensive networks, linkers, or compounds. A different approach CO2-epoxide coupling applying surface science methodologies graft molecular fragments single atoms on various supports leading well-defined active sites. In this context, organometallic chemistry (SOMC), along with comparable methodologies, a valuable efficient, single-site Lewis acids target reaction metal oxides, whereas, other grafting applied prepare analogous kinds surfaces. Finally, we discuss very recent advances in application atom towards highly epoxides. Overall, show prepared facile hold significant potential future synthesis from CO2.

Language: Английский

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Rapid atom-efficient polyolefin plastics hydrogenolysis mediated by a well-defined single-site electrophilic/cationic organo-zirconium catalyst

Nature Communications, Journal Year: 2022, Volume and Issue: 13(1)

Published: Nov. 23, 2022

Abstract Polyolefins comprise a major fraction of single-use plastics, yet their catalytic deconstruction/recycling has proven challenging due to inert saturated hydrocarbon connectivities. Here very electrophilic, formally cationic earth-abundant single-site organozirconium catalyst chemisorbed on highly Brønsted acidic sulfated alumina support and characterized by broad array experimental theoretical techniques, is shown mediate the rapid hydrogenolytic cleavage molecular macromolecular hydrocarbons under mild conditions, with onset as low 90 °C/0.5 atm H 2 0.02 mol% loading. For polyethylene, quantitative hydrogenolysis light proceeds within 48 min an activity > 4000 mol(CH units)·mol(Zr) −1 ·h at 200 °C/2 pressure. Under similar solventless polyethylene- co −1-octene, isotactic polypropylene, post-consumer food container cap are rapidly hydrogenolyzed mass hydrocarbons. Regarding mechanism, theory experiment identify turnover-limiting C-C scission pathway involving ß -alkyl transfer rather than more common σ-bond metathesis.

Language: Английский

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A co-anchoring strategy for the synthesis of polar bimodal polyethylene

Nature Communications, Journal Year: 2023, Volume and Issue: 14(1)

Published: March 15, 2023

Since polar groups can poison the metal centers in catalysts, incorporation of comonomers usually comes at expense catalytic activity and polymer molecular weight. In this contribution, we demonstrate bimodal polyethylene as a potential solution to trade-off. The more-polar/more-branched low-molecular-weight fraction provides polarity processability, while less-polar/less-branched high-molecular-weight mechanical melt properties. To achieve high miscibility between these two fractions, three synthetic routes are investigated: mixtures homogeneous separately supported heterogeneous co-anchoring strategy (CAS) heterogenize different catalysts on one solid support. CAS route is only viable for synthesis with good level entanglement minimal phase separation. This produces polyolefin materials excellent properties, surface/dyeing gas barrier well extrudability 3D-printability.

Language: Английский

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Heterogenization Strategies for Nickel Catalyzed Synthesis of Polyolefins and Composites

Accounts of Materials Research, Journal Year: 2023, Volume and Issue: 4(6), P. 496 - 506

Published: May 20, 2023

ConspectusPolyolefin is one of the most common synthetic polymers. However, polyolefins are nonpolar materials, which leads to poor compatibility with polar thus limiting their application in some fields. Polar functionalized can lead significantly improved dyeability, adhesiveness and fillers, realize customized properties polyolefin materials. Transition-metal-catalyzed coordination copolymerization olefin comonomers represents a direct potentially economic route synthesize polar-functionalized has attracted great attention recent decades. Literally hundreds nickel palladium catalysts have been synthesized investigated olefin-polar monomer achieve high efficiency by tuning molecular structures catalysts. In particular, earth-abundant low-cost nickel-based hold potential for industrial applications. research efforts focus on homogeneous catalysts, while industrially preferred heterogeneous systems remained largely unexplored. With objective bridging this gap, our group recently developed series heterogenization strategies synthesis high-performance taking advantage hydrogen bond anchoring, ionic coanchoring, cocatalyst, cluster formation. These involve known or easily accessible be adapted various catalytic systems, simultaneous enhancement all parameters such as thermal stability, activity, comonomer incorporation ratio, copolymer weight versus counterparts. addition, performance tuned changing type support, thereby facilitating discovery Most importantly, product morphology control achieved. This desirable polymerization processes because it avoids reactor fouling results significant improvements safety operational processes. Finally, these give access materials (polar-functionalized polyolefins, in-reactor blends polyolefin-based functional composites) custom-made properties. Compared melt blending, composites obtained situ better material By using prepared situ. applications many fields, electrical conductivity, photodegradation, flame retardancy, barrier, etc. It expected that continuous mechanism/catalysts, heterogenizatioin will eventually commercialization nickel-catalyzed production composites.

Language: Английский

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Heterogenized Molecular Rhodium Phosphine Catalysts within Metal–Organic Frameworks for Alkene Hydroformylation

ACS Catalysis, Journal Year: 2023, Volume and Issue: 13(7), P. 4193 - 4204

Published: March 13, 2023

Molecularly defined organometallic rhodium phosphine complexes were efficiently heterogenized within a MOF structure without affecting neither their molecular nature nor catalytic behavior. Phosphine-functionalized MOF-808 served as solid ligand in series of eight catalysts. These MOF-heterogenized catalysts showed activity up to 2100 h–1 for ethylene hydroformylation toward propionaldehyde the sole carbon-containing product. The combined experimental and computational methods applied this unique MOF-based system allowed unraveling evolution active Rh species under conditions, line with mechanisms at play during reaction. catalyst also successfully catalyzed longer bulkier alkenes similar selectivity than that obtained its homogeneous counterpart. MOF-808, designed porous crystalline macroligand well-defined catalysts, allows benefiting from scale understanding interactions well stabilization through site isolation recycling ability.

Language: Английский

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Outer‐Shell Self‐Supported Nickel Catalysts for the Synthesis of Polyolefin Composites

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 62(18)

Published: March 3, 2023

In situ heterogeneous olefin polymerization has attracted much attention for the synthesis of polyolefin composites. However, complicated syntheses specially designed catalysts or detrimental effects interactions between catalyst and solid supports pose great challenges. this contribution, an outer-shell self-supporting strategy was to heterogenize nickel on different fillers via precipitation homopolymerization ionic cluster type polar monomer. These demonstrated high activity, good product morphology control, stable performances in ethylene copolymerization. Moreover, various composites with mechanical customized properties can be efficiently synthesized.

Language: Английский

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Cationic Tantalum Hydrides Catalyze Hydrogenolysis and Alkane Metathesis Reactions of Paraffins and Polyethylene

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(9), P. 4964 - 4968

Published: Feb. 24, 2023

Sulfated aluminum oxide (SAO), a high surface area material containing sulfate anions that behave like weakly coordinating anions, reacts with Ta(═CHtBu)(CH2tBu)3 to form [Ta(CH2tBu)2(O-)2][SAO] (1). Subsequent treatment H2 forms Ta-H+ sites supported on SAO are active in hydrogenolysis and alkane metathesis reactions. In both reactions is more than related neutral Ta-H silica. This reaction chemistry extends melts of high-density polyethylene (HDPE), where converts 30% low molecular weight HDPE (Mn = 2.5 kg mol-1; Đ 3.6) paraffins under conditions. Under conditions this MW fraction 6.2 kDa; 2.3) products (C13-C32). These results show incorporating charge as design element d0 metal hydrides viable strategy increase the rate challenging involving reorganization C-C bonds alkanes.

Language: Английский

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Synthesis of Polar-functionalized Isotactic Polypropylenes Using Commercial Heterogeneous Ziegler–Natta Catalyst

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(10), P. 6837 - 6845

Published: March 1, 2024

The efficient synthesis of polar-functionalized polypropylenes with high molecular weight and stereoregularity represents a challenging task. This challenge becomes even more daunting when pursuing an industrially preferred heterogeneous process. study demonstrated the realization these goals through use commercial Ziegler–Natta catalysts in copolymerization propylene ionic cluster polar monomers. results revealed activity (∼1.1 × 107 g mol–1 h–1), moderate monomer incorporation ratios (∼4.9 mol %), copolymer (Mw > 105 mol–1), ([mmmm] ∼ 96%), melting temperature range (150–162 °C). utilization monomers improved thermal stability as well stereoselectivity catalyst. Moreover, catalyst can homopolymerize activities (>104 h–1). resulting isotactic (iPP) exhibited superior tensile strength, impact creep resistance, transparency, crystallinity compared nonpolar iPP. enhancement was attributable to dual roles unit, serving both transparent nucleating agent dynamic cross-linking functionality. Furthermore, iPP compatibility materials, offering benefits for applications composites, recycling mixed plastic wastes, 3D printing, other fields. offered comprehensive solution future industrial production via copolymerization, bridging gap between practical process from synthetic chemistry perspective enhanced material properties application perspective.

Language: Английский

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Recent advances in the design of high-performance cobalt-based catalysts for dry reforming of methane

Green Chemistry, Journal Year: 2024, Volume and Issue: 26(9), P. 5103 - 5126

Published: Jan. 1, 2024

In this review, many strategies, such as improving metal dispersion, strengthening metal–support interaction, increasing CO 2 adsorption and activation, promoting oxygen release/storage capacity, were proposed to improve catalytic performance of DRM.

Language: Английский

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Photoelectrochemical CO₂ Reduction to CO Enabled by a Molecular Catalyst Attached to High-Surface-Area Porous Silicon

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(12), P. 7998 - 8004

Published: March 15, 2024

A high-surface-area p-type porous Si photocathode containing a covalently immobilized molecular Re catalyst is highly selective for the photoelectrochemical conversion of CO2 to CO. It gives Faradaic efficiencies up 90% CO at potentials −1.7 V (versus ferrocenium/ferrocene) under 1 sun illumination in an acetonitrile solution phenol. The photovoltage approximately 300 mV based on comparisons with similar n-type cathodes dark. Using estimate equilibrium potential reduction optimized reaction conditions, photoelectrolysis was performed small overpotential, and onset electrocatalysis cyclic voltammograms occurred modest underpotential. photoelectrode more stable production than generated by attaching same planar wafer. Further, facile characterization Si-based photoelectrodes using transmission mode FTIR spectroscopy leads reproducible catalytic performance.

Language: Английский

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