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The terpolymerization of ethylene with hexene and styrene derivatives was achieved with a rare earth metal catalyst (C5Me4SiMe3)Sc(CH2C6H4NMe2-o)2 to prepare functional polyethylene. The catalyst system exhibited high activity in the terpolymerization of ethylene with hexene and amine-substituted styrene, affording terpolymers a moderate molecular weight and a unimodal molecular weight distribution. In addition, the comonomer content of the terpolymers can be controlled by changing the feeding ratio of monomers. The aliphatic region of the 13C NMR spectra reveals that the structural units of the comonomers are separately incorporated into the polyethylene backbone. Terpolymers containing styrene derivatives exhibit enhanced tensile strength and significantly improve hydrophilic properties. [ABSTRACT FROM AUTHOR]

An effective method has been developed for the synthesis of unique macrohetero[N,S]cycles 1,4,7(8,9,10,11,12,14)-trithia-2,9(10,11,12,13,14,16)-diazacycloalkane 1,1-dioxides by cyclothiomethylation of sulfonamide with bishydroxydithioalkanes and 1,3,6(7)-oxadithioalkanes in the presence of rare earth metal catalysts. A detailed conformational analysis of 1,4,7-trithia-2,9-diazacycloalkane 1,1-dioxide has been carried out, and the energetically most probable path of cyclic interconversion has been proposed. [ABSTRACT FROM AUTHOR]

Pt supported on carbon (Pt/C) is deemed as the state-of-the-art catalyst towards oxygen reduction reactions (ORRs) in chemical and biological fuel cells. However, due to the high cost and scarcity of Pt, researchers have focused on the development of Earth-abundant non-precious metal catalysts, hoping to replace the traditional Pt/C catalyst and successfully commercialize the chemical and biological fuel cells. In this regard, electrocatalysts made of transition metals emerged as excellent candidates for ORRs, especially the electrocatalysts made of Fe and Co in combination with N-doped carbons, which produce potentially active M-N4-C (M=Co, Fe) ORR sites. At present, however, the transition metal-based catalysts are popular; recently, electrocatalysts made of rare earth metals are emerging as efficient catalysts, due to the fact that rare earth metals also have the potential to form rare earth metal-N4-C active sites, just like transition metal Fe-N4-C/Co-N4-C. In addition, mixed valance states and uniqueness of f-orbitals of the rare earth metals are believed to improve the redox properties of the catalyst that helps in enhancing ORR activity. Among the rare earth metals, Ce is the most interesting element that can be explored as an ORR electrocatalyst in combination with the N-doped carbon. Unique f-orbitals of Ce can induce distinctive electronic behavior to the catalyst that helps to form stable coordination structures with N-doped carbons, in addition to its excellent ability to scavenge the OH● produced during ORRs, therefore helping in catalyst stability. In this study, we have synthesized Ce/N-C catalysts by a metal–organic framework and pyrolysis strategy. The ORR activity of Ce/N-C catalysts has been optimized by systematically increasing the Ce content and performing RDE studies in 0.1 M HClO4 electrolyte. The Ce/N-C catalyst has been characterized systematically by both physicochemical and electrochemical characterizations. The optimized Ce/N-C-3 catalyst exhibited a half-wave potential of 0.68 V vs. RHE. In addition, the Ce/N-C-3 catalyst also delivered acceptable stability with a loss of 70 mV in its half-wave potential when compared to 110 mV loss for Pt/C (10 wt.%) catalyst, after 5000 potential cycles. When Ce/N-C-3 is used as a cathode catalyst in dual-chamber microbial fuel cells, it delivered a volumetric power density of ~300 mW m−3, along with an organic matter degradation of 74% after continuous operation of DCMFCs for 30 days. [ABSTRACT FROM AUTHOR]

O2-Assisted oxidative dehydrogenation of propane (O2-ODHP) could convert abundant shale gas into propylene as an important chemical raw material, meaning O2-ODHP has practical significance. Thermodynamically, high temperature is beneficial for O2-ODHP; however, high reaction temperature always causes the overoxidation of propylene, leading to a decline in its selectivity. In this regard, it is crucial to achieve low temperatures while maintaining high efficiency and selectivity during O2-ODHP. The use of catalytic technology provides more opportunities for achieving high-efficiency O2-ODHP under mild conditions. Up to now, many kinds of catalytic systems have been elaborately designed, including transition metal oxide catalysts (such as vanadium-based catalysts, molybdenum-based catalysts, etc.), transition metal-based catalysts (such as Pt nanoclusters), rare earth metal oxide catalysts (especially CeO2 related catalysts), and non-metallic catalysts (BN, other B-containing catalysts, and C-based catalysts). In this review, we have summarized the development progress of mainstream catalysts in O2-ODHP, aiming at providing a clear picture to the catalysis community and advancing this research field further. [ABSTRACT FROM AUTHOR]

The selective conversion of levulinic acid (LA) obtained from lignocellulosic biomass represents a crucial pathway for producing the key value‐added chemical compound γ‐valerolactone (GVL). Herein, we constructed a series of Pt‐based titanium‐silicalite‐1 (TS‐1) bifunctional catalysts modified with rare earth metal Ce through a simple spin‐coating impregnation method, and the catalytic performance was significantly improved compared to the unmodified Pt1.2/TS‐1. Pt0.7‐Ce0.5/TS‐1 exhibited the best aqueous‐phase catalytic activity (with a GVL yield of 99.4%). The introduction of CeOx can reduce the particle size of Pt nanoparticles and promote the formation of electron‐rich Pt species while delivering abundant oxygen vacancies (OV) for the catalysts. The characterization and testing results highlight the synergistic effect of OV and electron‐rich Pt sites on the oriented adsorption and selective hydrogenation of LA, providing new insights into constructing more efficient noble metal‐based zeolite catalysts for biomass conversion. [ABSTRACT FROM AUTHOR]

Keywords: Lewis acids; homogeneous catalysis; water-tolerant; kinetic analysis; zirconium; amides; esters; ethers EN Lewis acids homogeneous catalysis water-tolerant kinetic analysis zirconium amides esters ethers 1678 1684 7 08/18/23 20230901 NES 230901 Graph Lewis acidic reagents and catalysts are highly versatile in synthetic chemistry as they promote a wide range of organic reactions. The zirconocene triflate catalyst was assessed in the model reaction using benzoic acid and 2-phenylethanol in an equimolar ratio (0.5 M), which proceeded reliably in aromatic solvents to form the ester product in ca. 70% yield after 24 hours at 80 °C. In addition, up to 50 equivalents of water to catalyst could be added to the reaction mixture without negatively affecting the reaction rate, whereas the addition of molecular sieves reduced the activity of the zirconocene catalyst. Lewis acids, homogeneous catalysis, water-tolerant, kinetic analysis, zirconium, amides, esters, ethers. [Extracted from the article]

(Co)poly-γ-butyrolactone (pGBL) is a thermoplastic material of high interest to replace common plastics with a more sustainable alternative due to its biodegradability, re-monomerizability and opportunity to be obtained from renewable feedstocks. Mild methods to produce pGBL by ring-opening polymerization (ROP) have only been developed in the last decade. Unfortunately, these methods involve the use of sophisticated catalysts, very low temperatures or relatively diluted mixtures. To develop a more environmentally, economically and industrially relevant pGBL synthesis process, the aim was to increase the ROP temperature to be applicable for large scale reaction and optimize the base/alcohol system to circumvent the use of sophisticated organic or rare earth metal catalysts. To that end, the strong base potassium tert-butoxide in combination with benzyl alcohol or with polyols such as 1,4-benzenedimethanol or glycerol was used for the ROP. This simple system gives access to high GBL conversions and medium to high molecular weight (co)polymers. [ABSTRACT FROM AUTHOR]

Due to the large ionic radius and high electro-positivity nature, rare earth metal complexes are difficult to stabilize and undergo pathways like ligand redistribution and intramolecular C-H activation. To solve such problems and retain reactive versatility, rare earth complexes supported by a variety of tridentate PNP pincer ligands have been explored. Such complexes can serve as perfect precursors for preparing ultra-active rare earth species containing two metal-carbon bands, let alone Ln=N and Ln=P multiple bonds. In addition, the combined stability and activity of the cation rare earth mediates made them the best catalysts for the polymerization of olefins and other non-polar hydrocarbon monomers, especially conjugated dienes. The practical utilization of rare earth metal catalysts for new materials production have also extensively explored by experts from the academic and industries. [ABSTRACT FROM AUTHOR]

Recently, biomass gasification process has gained lots of attention because of sustainable energy sources utilization. Being renewable energy source, biomass can serve as a viable replacement for fossil fuels. The process gasification is the conversion of organic substance via thermochemical process where syngas is produced along with the solid product termed as char. Such process is also well known for the generation of heat and power and synthesize the second-generation biofuels and hydrogen production. Unfortunately, tar formation in gasifiers during biomass gasification remains a main problem to commercialization. In the current review we focus at recent advancements in catalytic biomass gasification about supercritical water catalytic gasification and discuss on gasification process, parametric impact, biomass-pretreatment and catalytic deactivate mechanism in order to overcome the challenges and improve the catalytic yield. Future direction and critical prospective of catalytic biomass gasification are also discussed in this review. • The document delves into biomass gasification technology, encompassing both biochemical and thermochemical conversion methods, with a particular focus on supercritical water gasification. • The review explores the application of homogeneous and heterogeneous catalysts in supercritical water gasification, emphasizing the unique role of rare earth metal oxide catalysts. • The document outlines future research, including SCWG of real biomass, catalyst optimization, reaction mechanisms, and addressing equipment corrosion and blockage issues. [ABSTRACT FROM AUTHOR]

10.1007/s10973-016-5465-z 22 Grams J., Ryczkowski R., Sadek R., Chalupka K., Przybysz K., Casale S., Dzwigaj S. Hydrogen-rich gas production by upgrading of biomass pyrolysis vapors over NiBEA catalyst: Impact of dealumination and preparation method. Due to limited fossil fuel reserves, the global political situation, and progressive environmental pollution, the development of new methods of hydrogen production is highly demanded. Due to the insufficient selectivity of the biomass pyrolysis process, it is necessary to apply catalysts to enhance hydrogen-rich gas production [[15]]. [Extracted from the article]

Digoxin (DGN), a widely used cardiac glycoside steroid for treating heart diseases. The prescription dosage range of digoxin is 0.5 – 2.0 ng/mL and concentration above 2 ng/mL can lead to intoxication. To monitor and detect digoxin in blood level is essential to minimize the endanger toxicity of human health. Addressing this concern, here we prepare a cerium manganese oxide (CMO) catalyst by a simple chemical coprecipitation method followed by heat treatment. The CMO morphological and structural characteristics were investigated by various spectroscopic techniques. The electrochemical properties of CMO catalyst were evaluated using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques, which also determined its electrochemical performance. Due to the high conductivity and large surface area with abundant active sites, CMO catalyst was used as a modified electrode material for detecting DGN in biological samples. The CMO sensor exhibits excellent electrocatalytic performance, with a dynamic linear range of 7.81 ×10–6 pg/L to 430 ×10–6 pg/L. The limit of detection and limit of quantification (LOD and LOQ) were found to be 1.99 ×10–6 pg/L and 6.05 ×10–6 pg/L, respectively. Furthermore, the sensor's efficiency was validated through selectivity test and analysis of biological samples such as human blood and urine. [Display omitted] • The CMO catalyst was synthesized by coprecipitation method followed by annealing. • CMO modified GCE has excellent analytical performance for cardiac glycoside digoxin. • The sensor displayed wide linear range of 7.81 ×10–6 pg/L to 430 x 10–6 pg/L with the LOD of 1.99 ×10–6 pg/L. • The CMO modified electrode is appropriate for real-sample analysis in blood serum and urine samples. [ABSTRACT FROM AUTHOR]

• Catalysts modified by rare earth metals have efficient catalytic performance. • Inhibition of H 2 is greatly suppressed over 10Ni/A 1 Mg 4 O α. • Solid solution formed and induced surface defects in 10Ni/A 1 Mg 4 O α. • Stronger basicity modified by La and Ce performed to promote electron donate to Ni sites. • Ce and Y greatly improve the intrinsic activity of catalysts. The lack of detailed functions of different REMs in NH 3 decomposition to H 2 makes the efficient modified catalysts not rationally be designed though many REMs-modified catalysts have been reported. In this work, the 10Ni/A 1 Mg 4 O α (A = La, Ce, and Y) and 10Ni/MgO, in which supports were synthesized by the sol–gel method and Ni was loaded by the wet-impregnate method, were comparatively investigated to reveal the effect of REMs against NH 3 decomposition reaction. The presence of REMs enhanced the activity of 10Ni/A 1 Mg 4 O α and decreased the activation energy as greatly as by half compared to 10Ni/MgO. The produced H 2 in situ has little impact on the activity of 10Ni/A 1 Mg 4 O α , among which Ce has the most excellent H 2 desorption ability. The intrinsic activity of catalysts was improved better by Ce and Y than La and the best Ni particle size is around 6 nm according to TOF, though the Ni particle is the smallest (4.9 nm) in 10Ni/La 1 Mg 4 O α. The surface structure of catalysts was tuned by doping REMs, forming a solid solution and some defects (oxygen vacancies), which enhanced the interaction between active metal and support with obvious electron transfer from support to Ni obtaining a better Ni dispersion and making NiO easier to be reduced. Additionally, the catalysts doped by La or Ce possess more oxygen vacancy due to the changes of La 2 O 2 CO 3 and the valence of Ce, exhibiting stronger basic sites and better N 2 desorption capacity. The study offers a promising strategy for utilizing appropriate or multiple REMs to synthesize effective catalysts effectively for catalyzing NH 3 decomposition in the future. [ABSTRACT FROM AUTHOR]

[Display omitted] • The synthesized Ce 0.6 Zr 0.4 O 2 nanocrystals catalyzed MgH 2 exhibited exceptional hydrogen sorption kinetics performance. • MgH 2 + 7 wt% Ce 0.6 Zr 0.4 O 2 absorbed 6.02 wt% within 3 min at 150 ℃. • The capacity retention rate of the MgH 2 + 7 wt% Ce 0.6 Zr 0.4 O 2 composite remains ∼ 98.9 % after 20 cycles at 270 °C. • The apparent activation energy E a of dehydrogenated reaction has reduced by ∼ 45 %. • The in-situ formed CeH 2.73 /CeO 2-x and ZrO 2 enhanced the de-/absorption properties of Ce 0.6 Zr 0.4 O 2 catalyzed-MgH 2. Magnesium hydride (MgH 2) has been widely recognized as a highly promising solid-state media for hydrogen storage. However, the high operating temperature and the intrinsic sluggish kinetics hinder the practical application as a portable solid storage carrier. To address this issue, we have successfully fabricated a novel rare earth-containing bimetallic oxide additive, namely Ce 0.6 Zr 0.4 O 2 nanocrystals, which exhibits a significant catalytic effect in enhancing the hydrogen storage properties of MgH 2. By incorporating 7 wt% Ce 0.6 Zr 0.4 O 2 into MgH 2 , the modified composite releases hydrogen as low as 201 °C. Furthermore, in an isothermal dehydrogenation test conducted at 270 °C for 8 min, approximately 6.15 wt% of H 2 was desorbed. The composites can rapidly recharge hydrogen at a low temperature of 50 °C and 6.02 wt% H 2 being absorbed within 3 min at 150 °C under 50.0 bar. Comparatively, the dehydrogenation activation energy of the Ce 0.6 Zr 0.4 O 2 -modified MgH 2 significantly decreased compared to MgH 2 by ball milling. In addition to its improved hydrogen storage properties, the composite also exhibits excellent cycling stability. Through cyclic de-/rehydrogenation experiments conducted at 270 °C, a capacity retention of 98.9 % was achieved over 20 cycles. This exceptional performance can be attributed to the in-situ formation of the CeH 2.73 /CeO 2-x and ZrO 2 , which originated from the Ce 0.6 Zr 0.4 O 2 additive following the first de-/rehydrogenation cycle. The uniform dispersion of the multiphase component nano-sized active species within the MgH 2 matrix facilitates charge transfer and accelerates hydrogen diffusion. Density functional theory calculations revealed the dissociation energy barrier and dissociation energy of H 2 were alleviated by integrating Zr into CeO 2. This work provides valuable insights for further rational designs of novel catalysts by transition metals and rare earths in promoting the commercialization of MgH 2. [ABSTRACT FROM AUTHOR]

• The ORR reaction pathway and catalytic mechanism of rare earth-based catalysts are briefly described. • The latest progress of rare earth-based ORR catalysts is systematically summarized. • Rare earth elements play an indispensable role in improving the activity of electrocatalytic materials through the formation of heterostructure interface, doping/substitution engineering, strain effect, etc. Rare earth (RE) metals have special 4f shell electronic configuration and special physical and chemical properties. Therefore, rare-earth-based catalysts are extensive used in the electrochemical cathodic oxygen reduction reaction (ORR) of proton exchange membrane (PEM) fuel cells. However, the low conductivity and low active site density of these catalysts limit their effective application in electrochemistry. The results show that the oxygen reduction activity and stability of rare-earth-based catalysts can be significantly improved by controlling the electronic structure and spatial configuration of active sites through doping of metal/nonmetal elements. In this paper, the main research work on metal/nonmetallic element doping to improve the performance of rare earth-based-catalysts in recent years was reviewed, including noble metal element doping, non-noble metal element doping, non-metallic element doping, perovskite and so on. The paper further summarized and pointed out the problems and challenges faced by rare-earth-based catalysts, and looked forward to their development prospects and future research directions. In recent years, rare earth metals have been widely used in the electrochemical cathodic oxygen reduction (ORR) of fuel cells because of their special 4f shell electronic structure and special physical and chemical properties. However, the low conductivity and low active site density of these catalysts limit their effective application in electrochemistry. The results show that the electronic structure and spatial configuration of the active sites can be significantly improved by doping metal/non-metal elements, which can significantly improve the oxygen reduction activity and stability of the rare-earth based catalysts. In this paper, the main research work on improving the performance of rare earth-based catalysts doped with metal/non-metal elements at home and abroad in recent years is reviewed, and their development prospects and future prospects are also prospected. [Display omitted] [ABSTRACT FROM AUTHOR]

Transitioning to lower carbon energy and environment sustainability requires a reduction in greenhouse gases such as carbon dioxide (CO2) and methane (CH4) that contribute to global warming. One of the most actively studied rare earth metal catalysts is cerium oxide (CeO2) which produces remarkable improvements in catalysts in dry reforming methane. This paper reviews the management of CO2 emissions and the recent advent and trends in bimetallic catalyst development utilizing CeO2 in dry reforming methane (DRM) and steam reforming methane (SRM) from 2015 to 2021 as a way to reduce greenhouse gas emissions. This paper focus on the identification of key trends in catalyst preparation using CeO2 and the effectiveness of the catalysts formulated. [ABSTRACT FROM AUTHOR]

Platinum (Pt) is considered as the most efficient catalyst for hydrogen evolution reaction (HER) with a nearly zero overpotential, but it is limited by the high cost and poor stability. Herein, we report an efficient electrocatalyst of Pt–Ni alloy nanoparticles (NPs) supported on the La-modified flexible carbon nanocomposite fibers (PtNi@La-CNFs) for HER. The rare earth metal oxide in the catalyst has a structure-effect relationship with the carbon fibers to form a flexible fiber membrane. Experimental results show that the macroscopic and microscopic properties of carbon nanocomposite fibers can be optimized by doping La 2 O 3 , and the Pt–Ni NPs can be anchored effectively. The Pt 1 Ni 1 @La-CNFs electrocatalyst exhibits a small overpotential of 32 mV to achieve current density of 10 mA cm−2 with a low Tafel slope of 51 mV dec−1 in alkaline medium, outperforming that of Pt@La-CNFs and the commercial Pt/C catalyst. This study reveals that the multiple coupling effect of rare earth compound, precious metal, and transition metal in composite catalyst can tailor its the electronic configuration, and results in an enhanced HER performance. This work opens up a novel approach to design high active and low cost Pt-based HER catalysts. • La-modified improved flexibility and mechanical strength of the CNFs. • Pt–Ni metal alloys particles enhanced the HER activity through internal electron transfer. • Better electrocatalytic performance than the commercial Pt/C catalyst. [ABSTRACT FROM AUTHOR]

[Display omitted] • The influence of the rare earth metals (Ce, La, and Y) was investigated on the 50 wt% Ni/Al 2 O 3 catalyst. • The Y promoter demonstrated 68.61 % CH 4 conversion with higher BET = 139.23 m2 g. • 5 wt% Y loading led to highly graphitized and the formation of carbon lattice with supreme crystalline. • The 50Ni-5Y/Al 2 O 3 catalyst has remained completely stable after 10 h at 575 °C. Catalytic methane decomposition is an economical and green procedure to procreate CO x -free hydrogen as a renewable energy source. This paper describes the mesoporous high surface area Ni/Al 2 O 3 catalysts enhanced with the rare earth metals (cerium, lanthanum, and yttrium) fabricated via neoteric one-pot hydrothermal strategy, and the co-catalysts performance in the methane decomposition process, explores. This comparative study shows that Yttria exhibited dramatic catalytic activity and thermal stability among the above promoters. The maximum CH 4 conversions of 61.16, 68.61, and 63.74 % have been obtained over the 50Ni-xY/Al 2 O 3 (x = 2.5, 5, and 10 wt%) at 650 °C and GHSV = 24000 mL.(h.g cat)−1, respectively. The optimal sample (5 wt% Y-doped) reveals a superior lifetime in high-temperature stability tests after 10 h. Moreover, the analysis of carbon nanofiber's textural properties indicates that Y loading leads to highly graphitized (I D /I G = 1.22 to 0.98) and the formation of a carbon lattice with supreme crystallization. [ABSTRACT FROM AUTHOR]

This paper reports about the production of syngas from dry reforming of ethanol (EDR) upon LaCuO 3 and CeCuO 3 catalysts that were prepared by using citrate sol-gel method. EDRs were run with fresh catalyst at each varied variable and 42 L/g cat /h of feed in a tubular reactor under atmospheric pressure. At equal feed pressure of reactants, steady state CO 2 conversion increased exponentially from 700 to 800 °C while H 2 and CO yields were increasing differently in sigmoid trend rendering H 2 /CO ratios to drop linearly from 1.7 to 1.0. However, these reaction results except the latter are otherwise when ethanol-CO 2 ratio was increased (reducing CO 2 pressure) at 750 °C. A minimum H 2 /CO ratio was evidenced at the ethanol-CO 2 ratio of 1.48. LaCuO 3 catalyst was more superior in producing syngas owing to its relatively low reduction temperature, high surface area and crystallinity, many active sites, good surface morphology and many C –O, C –H and hydroxyl groups. • Characterization of LaCuO 3 and CeCuO 3 catalysts prepared by using the sol-gel method. • Yield of hydrogen and CO from catalytic ethanol dry reforming at different reaction temperatures and feed ratios. • The ratio of hydrogen to carbon monoxide as syngas product from the ethanol dry reforming reaction. • Relation between characterization results and the reaction results. [ABSTRACT FROM AUTHOR]

Summary Methane is the main component of natural gas. The effective activation of C‐H bond of methane to synthesize value‐added compounds under mild conditions is attractive. Compared to the most investigated noble metal catalysts (such as Au, Pd, and Rh), rare earth metal catalysts possess stronger oxidizing activity. Herein, we report the first synthesis of Ce cation‐based phosphomolybdic salt (CePMo12O40) with a simple milling method. Furthermore, CePMo12O40‐based TiO2 catalyst (CePMo/TiO2) exhibited excellent catalytic performance for selective conversion of methane, achieving high yield (5618.5 μmol/gcat) of organic oxygenates (CH3OOH, HCOOH, and HCHO) using O2 as an oxidant in water at 150°C under 1.5G sunlight irradiation for 2 hours. It was found that the yield of total produced organic oxygenates over CePMo/TiO2 is 119% larger with 1.5G sunlight light irradiation than that without the light irradiation. In addition, the introduction of CePMo into TiO2 increased its photocatalytic activity for organic oxygenates by 11%. The isotope‐labeling evaluation revealed that both H2O and O2 participated the oxidation of methane into CH3OOH, HCOOH, and HCHO. This work provides the first example of rare earth POM‐based photocatalysts for conversion of methane into liquid oxygenates. [ABSTRACT FROM AUTHOR]

Understanding how the local environment of a “single-atom” catalyst affects stability and reactivity remains a challenge. We present an in-depth study of copper1, silver1, gold1, nickel1, palladium1, platinum1, rhodium1, and iridium1 species on Fe3O4(001), a model support in which all metals occupy the same twofold-coordinated adsorption site upon deposition at room temperature. Surface science techniques revealed that CO adsorption strength at single metal sites differs from the respective metal surfaces and supported clusters. Charge transfer into the support modifies the d-states of the metal atom and the strength of the metal–CO bond. These effects could strengthen the bond (as for Ag1–CO) or weaken it (as for Ni1–CO), but CO-induced structural distortions reduce adsorption energies from those expected on the basis of electronic structure alone. The extent of the relaxations depends on the local geometry and could be predicted by analogy to coordination chemistry. [ABSTRACT FROM AUTHOR]

Janus polymerization is featured as a combination of cationic and anionic growing ends in one living polymer chain. In the copolymerization of THF and CL catalyzed by lutetium triflates and initiated by propylene oxide, three stages are identified by kinetic study including (1) fast cationic polymerization with slow anionic one, (2) fast anionic polymerization with dormant cationic one, and (3) reactivation of cationic polymerization with coupling of anionic and cationic chain ends. In this work, density functional theory (DFT) calculation is employed to investigate the reaction details of ionic polymerization and dormancy. A "tripedal crow" configuration is proposed to illustrate the unique high-coordinated ligand exchange configuration in anionic polymerization in different stages. The trigger of dormancy is determined as chain structures rather than concentration of triflate anion according to both calculation and experimental results. [ABSTRACT FROM AUTHOR]

Functionalized aliphatic polyesters attract increasing attentions as biocompatible and biodegradable polymers with broad applications in biological science. In this contribution, we propose a facile and controllable synthetic technique for functional poly(ε- caprolactone) (PCL) via Janus polymerization, which comprises cationic ring-opening copolymerization (ROP) of ε-caprolactone (CL) with 3,3-bis(chloromethyl) oxacyclobutane (CO) and (coordinated) anionic ROP of CL at a single propagating chain by rare earth metal triflates (RE(OTf)3) and propylene oxide, thus generating block copolymers in one step. The compositions of the copolymers of poly(CLb-(CL-r-CO)) can be modulated by various RE(OTf)3. Scandium triflate catalyzes Janus polymerization to yield the copolymers containing the highest CO contents among all the RE(OTf)3 catalysts used with complete conversion of CL. The chlorine in CO repeating units is ready to be transferred into azide group which affords the modification sites to react with 9-ethynyl-9-fluorenol and mPEG-alkyne, respectively, via copper(I)-catalyzed azide-alkyne cycloaddition reaction with quantitative conversions of azides, as confirmed by FTIR analyses. According to NMR and SEC analyses, copolymers (PCC-g-PEG) bearing a homo-PCL block and a PEG-grafted block of poly(CO-co-CL) demonstrate well-defined chemical structures. The investigations on thermal properties reveal the strong phase separation between PCL and PEG blocks. The amphiphilic PCC-g-PEG is able to self-assemble into micelles in aqueous solution while cylindrical and lamellar morphologies are observed in bulk. We provide an efficient protocol to synthesize functional PCL combining onestep Janus polymerization and precise post-polymerization click reaction. [ABSTRACT FROM AUTHOR]

Abstract The effects of rare-earth elements M = Gd, Er, and La and alkali metals M = K, Li, Na, and Rb substitutions on Tl 0.7 M 0.3 Sr 2 Ca 0.8 Cr 0.2 Cu 2 O 7 (Tl-1212) were investigated. The characterization includes X-ray diffraction method, scanning electron microscopy, electrical resistance and AC susceptibility measurements. X-ray diffraction patterns showed that almost all samples consisted of major Tl-1212 and minor Tl-1201 and Ca 0.3 Sr 0.7 CuO 2 phase. Rare-earth elemental substitution improved the formation of the Tl-1212 phase but suppressed the transition temperature. Scanning electron micrographs showed smaller grain size in the substituted samples compared with non-substituted sample. The temperature-dependent electrical resistance measurements showed metallic normal state behavior for all samples. Alkali metals substitutions showed higher zero transition temperature, T c-zero compared with the rare-earth elemental substitution. AC susceptibility measurements showed a higher superconducting transition, T cχ′ for alkali metals substitutions (84–93 K) compared with the rare-earth elemental substitutions (50–61 K). The inter-grain critical current density at the peak temperature T p of the imaginary part χ", J c (T p) measured using the Bean's model was between 17 and 22 A cm−2. The effects of rare-earth elements and alkali metals substitutions were discussed in terms of ionic radius and the concept of average Cu valence. Highlights • Rare-earth elements enhanced Tl-1212 phase but severely suppressed T c. • Alkali metals suppressed Tl-1212 phase but T c was not severely suppressed. • Optimally doped Tl-1212 was severely affected by rare-earth but not by alkali metal. [ABSTRACT FROM AUTHOR]

A highly efficient strategy for the synthesis of polylactide with the UV absorption ability was established by employing a Salan-yttrium complex (acting as a fast runing catalyst) combined with large excess hydroxyl functionalized benzophenone, BP′-OH. During polymerization, BP′-OH, acting as the chain transfer agent, attached to the active rare-earth metal catalyst via a rapid-reversible exchange reaction to initiate the polymerization. Thus, more polyester chains appeared to grow from one active metal species, and the UV absorption fragments were incorporated into the polymer chains at specific sites, in situ. A high productivity up to 1000 molLA/mol(Salan-Y) was successfully achieved and 100 BP′-labeled PLA chains grew from each active metal center. [ABSTRACT FROM AUTHOR]

The use of ligands to tune the reactivity and regioselectivity of transition metal‐based catalyst for silicon‐mediated organic synthesis (SiMOS) is an important topic and challenge in organosilicon chemistry and synthetic organic chemitstry. In this manuscript, the dual ligand platinum catalyst system was developed for the hydrosilylation of alkynes. It was found that regioselectivity enhancement was determined with combinational use of phosphine ligand (6a) and multifunctional Py‐BINMOL ligand (4a). The corresponding vinylsilanes were obtained in high yields and high regioselectivities. [ABSTRACT FROM AUTHOR]

Rare-earth metal complexes (Flu-CH2-Py)Ln(CH2SiMe3)2(THF) n (Ln=Sc( 1), Lu( 2), Tm( 3), Y( 4) and Gd( 5)), upon the activation of [Ph3C][B(C6F5)4] and Al iBu3, were employed to catalyze the polymerization of allene derivatives under mild conditions. The Gd, Y, Tm, Lu metal based precursors exhibited distinguished 2,3-selectivity (>99.9 %) for phenylallene (PA) polymerization, whereas the smallest Sc metal based precursor showed a moderate 2,3-selectivity. The activity increased with the central metal size following the trend of Gd( 5)>Tm( 4)>Y( 3)>Lu( 2)>Sc( 1). Moreover, Gd( 5) also realized the purely 2,3-selective polymerizations of polar or nonpolar allene derivatives, para-methylphenylallene, para-flourophenylallene and para-methoxyphenylallene, regardless of electron-donating or -withdrawing substituents. Owing to the highly regular backbones, these polymers (except PPA) were crystalline, thus being the first crystalline polymers based on allene derivatives. [ABSTRACT FROM AUTHOR]

The complexes of rare-earth metals (Y, La, Sm and Lu) with a chiral tridentate amido-fluorenyl ligand were synthesized and characterized. These complexes demonstrated high efficiency in catalyzing both the intramolecular hydroamination of non-activated olefins and the cyanosilylation of ketones under very mild conditions, however, with no enantiocontrol being achieved. 1 H NMR monitoring of the reaction process suggests the weak coordination capacity of the fluorenyl moiety might be responsible for the lack of asymmetric inducing power of the chiral complexes in such transformations. [ABSTRACT FROM AUTHOR]

The stereoselective and sequence controlled coordination copolymerizations of butadiene (BD) and styrene (St) with diblock, tapered, gradient, and random sequence distributions were achieved for the first time through varying the central metals of the rare-earth metal bis(alkyl) catalyst precursors (Flu-CH2-Py)Ln(CH2SiMe3)2(THF)x (Flu = fluorenyl, Py = pyridyl, x = 1: Ln = Nd(1), Y(2), Tm(3); x = 0, Ln = Sc(4)). The thermal behavior, morphology, and the mechanical property of these copolymers were analyzed, and their relationships were established for the first time. The mechanism of central metal size tuning the sequence distribution was discussed based on DFT calculations. [ABSTRACT FROM AUTHOR]

In their Research Article, M. E. Fieser and co-workers explore the combination of rare earth metal trichloride salts with a phosphonium chloride ionic liquid to form metal-containing ionic liquids. These MILs exhibited improved rates of polymerization and faster growth of high molecular weight polymers than previous simple rare earth metal salt catalysts systems. Keywords: yttrium; lanthanides; ionic liquids; ring-opening polymerization; polymers EN yttrium lanthanides ionic liquids ring-opening polymerization polymers 1 1 1 07/14/23 20230622 NES 230622 B The Front Cover b (designed by Rika Mizoguchi) shows a Metal Ionic Liquid fertilizer catalyzing the growth of perfectly alternating copolymers of various epoxides and cyclic anhydrides, represented as growing vines. [Extracted from the article]

Chiral N,N'-dioxide/Y(OTf)3 and Sc(OTf)3 complexes have been developed as efficient catalysts for the bisvinylogous Mukaiyama aldol reaction of silyl ketene acetal with α-ketoesters and aldehydes, respectively. The catalytic systems were highly ε-selective, and the substrate scope was wide. The corresponding ε-hydroxy-α,β,γ,δ-unsaturated esters were obtained in up to 95% yield and 98% ee. [ABSTRACT FROM AUTHOR]

A series of neutral lanthanide alkoxide complexes stabilized by a new salen-type Schiff-base ligand were synthesized, and their catalytic behaviors for the ring-opening polymerization of lactide were explored. Amine elimination reactions of N -methyl- N ′, N ″-bis(3,5-di- tert -butylsalicylidene)-2,2′-diaminodiethylamine (LH 2 ) with Ln[N(SiMe 3 ) 2 ] 3 (Ln = Sm, Nd, La) in a 1:1 M ratio in THF, followed by reactions with 1 equiv of alcohols ( t BuOH, EtOH and CH 3 OCH 2 CH 2 OH), produced lanthanide alkoxide complexes LLn(O t Bu)(THF) (Ln = Sm ( 1 ), Nd ( 2 ), La ( 3 )), [LSm( μ -OEt)] 2 ( 4 ) and [LSm( μ -OCH 2 CH 2 OCH 3 )] 2 ( 5 ), respectively, whereas the same reaction with Yb[N(SiMe 3 ) 2 ] 3 gave an unexpected homoleptic complex L 2 Yb 2 ( μ -L) ( 6 ). X-ray structural determination showed that complexes 1 – 3 have a THF-solvated monomeric structure, whereas complexes 4 – 6 have an unsolvated dimeric structure. All lanthanide alkoxide complexes can efficiently initiate the ring-opening polymerization (ROP) of L -LA and rac -LA. The polymerization kinetics of L -LA initiated by complex 1 has been studied in detail and the first-order kinetic dependence on both l -lactide concentration and initiator concentration was found. Furthermore, all complexes showed moderate stereoselectivity for rac -LA polymerization to afford heterotactic-rich polylactides. [ABSTRACT FROM AUTHOR]

The C-H polyaddition of dimethoxyarenes such as 1,4-dimethoxybenzene and 4,4'-dimethoxybiphenyl to unconjugated dienes such as norbomadiene and 1,4-divinylbenzene has been achieved for the first time by using cationic half-sandwich rare earth alkyl catalysts. This protocol afforded novel polymer materials consisting of dimethoxyarene moieties and nonpolar hydrocarbon structure motifs (cyclic, linear, and aromatic) in perfectly alternating sequences that are otherwise difficult to make. The reaction proceeded via C=C double bond insertion into a C-H bond ortho to each of the two methoxy groups in a step-growth polymerization fashion. [ABSTRACT FROM AUTHOR]

In this paper, we investigated the DME ATR reaction with different types of precious metal (Pt, Rh, Ru)-supported CGO catalysts. We also evaluated the reaction characteristics of DME ATR reaction by modifying certain reforming conditions, including the temperature, the amount of air and water, and the flow rate. The Ru-added CGO catalyst showed the best performance in DME ATR. The operating condition that produced the greatest effect on conversion efficiency was temperature; however the amounts of steam and air were also important with regard to conversion efficiency and the reaction heat. In case higher GHSV conditions the methane yields are increased. To maximize conversion efficiency with thermal neutral operating conditions, we suggest an SCR of 1.5, OCR of 0.45, over temperature of 700 °C, and a GHSV of less than 20,000/h. Under harsh conditions, such as low temperature and high GHSV, the methane yield increases. Therefore, the high temperature DME ATR reaction seems to consist of two main steps: the DME decomposition to methane and the methane autothermal reforming reaction. [ABSTRACT FROM AUTHOR]

The lanthanide-catalyzed oxidative C-O coupling of 1,3-dicarbonyl compounds with diacyl peroxides, specifically the cyclic malonyl peroxides, has been developed. An important feature of this new reaction concerns the advantageous role of the peroxide acting both as oxidant and reagent for C-O coupling. It is shown that lanthanide salts may be used in combination with peroxides for selective oxidative transformations. The vast range of lanthanide salts (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Y) catalyzes oxidative C-O coupling much more efficiently than other used Lewis and Bronsted acids. This oxidative cross-coupling protocol furnishes mono and double C-O coupling products chemo-selectively in high yields with a broad substrate scope. The double C-O coupling products may be hydrolyzed to vicinal tricarbonyl compounds, which are otherwise cumbersome to prepare. Based on the present experimental results, a nucleophilic substitution mechanism is proposed for the C-O coupling process in which the lanthanide metal ion serves as Lewis acid to activate the enol of the 1,3-dicarbonyl substrate. The side reactions-chlorination and hydroxylation of the 1,3-dicarbonyl partners-may be minimized under proper conditions. [ABSTRACT FROM AUTHOR]

Lanthanide-based catalysts are highly active for isoprene polymerization in hexane. In this paper, a ternary catalyst consisting of neodymium neodecanoate {Nd(vers)3}, Al(iBu)3 and Al(iBu)2Cl was studied by using X-ray-absorption fine-structure (XAFS) technique. A sealed and moisture-proof liquid sample cell with adjustable thickness was designed for Nd LIII-edge XAFS measurements. Based on the XAFS data analysis, detailed structure changes around the Nd center were obtained. It was found that the Nd(vers)3 molecules formed an oligomer structure in hexane solution with two Nd–O subshells (5O @ 2.39 Å and 5O @ 2.54 Å) around the Nd center. The alkylation process by adding Al(iBu)3 to the hexane solution of Nd(vers)3 partially destroyed the aggregation degree of Nd(vers)3 molecules in hexane solution. Al(iBu)3 ligands were bonded to the Nd center by Nd–C bonding. With the Nd : Al ratio increasing from 1 : 2.5 to 1 : 10, the O neighbors around Nd decreased from 4 to 2 but with an unchanged Nd–O bond length of 2.38 Å, and the C neighbors around Nd were kept at ca. 4 with Nd–C bond lengths in the range of 2.57–2.58 Å. The Nd–O bonds can be further replaced by Nd–C bonds during the aging process. The chlorination process by adding Al(iBu)2Cl to the mixture solution of Nd(vers)3 and Al(iBu)3 restrained intensively the agglomeration of Nd(vers)3 molecules in hexane solution. Al(iBu)2Cl ligands were bonded to the Nd center by Nd–Cl bonds. There were about 3–4 C neighbors at 2.58 Å, 2 Cl neighbors at 2.87 Å, and 2 Al next-neighbors at 3.14 Å around the Nd center. After allowing the ternary catalyst to stand for 5 days, the coordination numbers of Nd–C and Nd–Cl were all stabilized to 3 without bond length changes, and partial single Cl− anions were also bonded to the Nd center. All these structural details and their change tendency demonstrate that the decrease of aggregation degree of Nd(vers)3 molecules in hexane solution can improve the catalytic activity of the ternary lanthanide-based catalyst system. [ABSTRACT FROM AUTHOR]

Molecular hydrides of the rare-earth metals play an important role as homogeneous catalysts and as counterparts of solid-state interstitial hydrides. Structurally well-characterized non-metallocene-type hydride complexes allow the study of elementary reactions that occur at rare-earth-metal centers and of catalytic reactions involving bonds between rare-earth metals and hydrides. In addition to neutral hydrides, cationic derivatives have now become available. [ABSTRACT FROM AUTHOR]

Recent studies have shown that rare earth metal-mediated group transfer polymerization (REM-GTP) can be applied to a variety of polar monomers, besides the classic (meth)­acrylates or (meth)acrylamides, giving access to new polymeric materials. This article highlights progress in this new field and gives a current overview of the initiation and propagation of vinylphosphonates, the extension to Michael-type nitrogen-coordinating monomers, and application to block copolymers, statistical copolymers, and 2D and 3D structures. Based on molecular understanding and high-precision synthesis, REM-GTP represents a versatile method for the preparation of new materials. [ABSTRACT FROM AUTHOR]

To improve the photoeatalytic efficiency of TiO2 for amoxicillin removal, a series of precious metals catalysts (M/TiO2, M = Ru, Rh, Pd, Ag, Ir, Pt or Au) were prepared by light deposition method. The synergistic photocatalytic activity of M/TiO2 with KBrO3 for degradation of amoxieillin (20 mg/L) in aqueous solution was researched under UV light (365 nm). The effects of metal loading, catalyst concentration, KBrO3 concentration and pH on the photoeatalytie activity of Rh/TiO2 with KBrO3 were explored. The results show that the photoeatalytie activity of M/TiO2 is closely related to its work function and KBrO3 has a greatly synergistic role on M/TiO2. Under the conditions of 0.1% Rh loading, Rh/TiO2 concentration of 0.15 g/L, KBrO3 concentration of 0.5 mmol/L and reaction liquid pH value at 5, the amoxicillin can be degradated completely within 90 min. Furthermore, the results of kinetic study show that the degradation reaction can be expressed by the first-order reaction kinetic model. [ABSTRACT FROM AUTHOR]

Rare-earthmetal bis(alkyl) complexes (Flu–NHC)Ln(CH2SiMe3)2(Ln = Dy (1), Er(2), Sc (3)) attached by fluorenyl-modifiedN-heterocyclic carbene ligands ((Flu H–NHC–H)Br) havebeen synthesized by treatment of (FluH–NHC–H)Brwith (trimethylsilylmethyl)lithium (LiCH2SiMe3) and rare-earth metal tris(alkyl)s (Ln(CH2SiMe3)3(THF)2) via double-deprotonation reactionsin moderate to high yields. Under mild conditions (40 °C andnormal ethylene pressure), the scandium precursor 3,upon activation of AliBu3and[Ph3C][B(C6F5)4], showedhigh activity (4120 kg molSc–1h–1atm–1) for the copolymerizationof ethylene and 1-hexene with moderate 1-hexene insertion ratio (20.2%),although the analogous complexes 1and 2were inert. In addition, this system displayed excellent catalyticperformances for the copolymerization of ethylene and a higher α-olefin1-octene with an activity of up to 3640 kg molSc–1h–1atm–1. The content of 1-octenecould be controlled swiftly from 2.1% to 38.7% by varying the 1-octenefeed ratio. Thus the isolated P(E-co-Oct) polymers varied from opaquecrystalline solids with high melting points, e.g., Tm= 103.6 °C, to transparent elastomers. This representsthe first rare-earth metal based homogeneous catalyst that can initiatethe copolymerization of ethylene and 1-octene, the catalytic performancesof which are comparable with those reported for the most active group4 metallocene systems. [ABSTRACT FROM AUTHOR]

Abstract: A series of itaconate esters, e.g. dimethyl itaconate, dibutyl itaconate and diisooctyl itaconate, were synthesized using solid acid SO4 2−/MxOy (M=Ti4+, Fe3+, Zr4+, Al3+) and SO4 2−/TiO2–SiO2 modified with lanthanide ion (Ln=La3+, Ce4+, Sm3+) as catalysts. It was found that SO4 2−/TiO2–SiO2 modified with lanthanide ion were of the same excellent catalytic activity as sulfuric acid (H2SO4). Moreover, Ln∼SO4 2−/TiO2–SiO2 is of excellent stability. Take La3+∼SO4 2−/TiO2–SiO2 for example, the influence of the preparation conditions on catalytic performance was in detail examined by Py-FTIR, NH3-FTIR, XRD and NH3-TPD, and the optimum preparation conditions were obtained. Furthermore, the effective separation of product combined with the recyclable catalyst is expected to contribute to the development of clean and environmental friendly strategy for the synthesis of itaconate esters. [Copyright &y& Elsevier]

The following article from the Journal of Applied Polymer Science, 'Palladium (II)-Rare Earth Metal Catalyzed Copolymerization of CO and Styrene in [bmim]+PF6− Ionic Liquid' by Jintang Guo, Guang Hu, Shan Gao, and Peng Li, published online on 14 November 2011 in Wiley Online Library (wileyonlinelibrary.com), has been retracted by agreement between the authors; the journal's Managing Editor, Stefano Tonzani; and Wiley Periodicals, Inc. The retraction has been agreed due to the inappropriate use of previously published work, in particular Figures 6 and 7. [ABSTRACT FROM AUTHOR]

Abstract: We report a series of novel, highly efficient, hydrolytically stable and recyclable Lewis acid rare earth triflate catalysts for the living/controlled bulk ring-opening polymerization (ROP) of tetrahydrofuran (THF) in the presence of epoxides. The rare earth triflates [RE(OTf)3] include that of Sc, Y, La, Nd, Dy and Lu. Epoxides include propylene oxide (PO), cyclohexene oxide (CHO) or styrene oxide (SO). Especially RE(OTf)3/PO shows high activities, producing PTHF with up to 62 percent conversion and relatively narrow molecular weight distributions (MWDs) (as low as 1.14). Molecular weights (MWs) can be readily controlled from 1.7 to 56.1 kDa by changing monomer to catalyst molar ratios. The Sc(OTf)3/PO catalyst gives an α,ω-dihydroxyl telechelic PTHF with MWs close to calculated values and MWDs below 1.2. The rare earth catalysts are easily recovered by simple water extractions. For instance, Sc(OTf)3 can be used at least six times without an obvious decrease of catalytic activity. A polymerization mechanism involving the first two propagation steps of the alkyltetrahydrofuranium cation is proposed to account for the induction periods observed. [Copyright &y& Elsevier]

O-Aryllithium complexes are easily preparedfrom stable aminophosphonium salts, and their coordination to rare-earthmetals was studied. The ligand to metal ratio in the formed complexeswas shown to depend exclusively on the substituent on the nitrogenatom of the ligand. Aryllithium derivatives 3aand 3b, exhibiting bulky groups (SiMe3and tBu, respectively), gave monocoordinated yttrium complexes 4a-Y and 4b-Y. On the other hand, with aryllithium 3a, possessing an isopropyl at nitrogen,complexes of YIII, NdIII, and GdIIIwith a 2:1 ligand to metal ratio could be obtained. Finally withless hindered ligands such as 6c, featuring an n-butyl substituent, triscoordinated Y, Nd, and La complexeswere accessible. X-ray crystal structures have been obtained withall three stoichiometries. These complexes were employed as catalystprecursors for 1,3-butadiene polymerization using various activators.Yttrium complexes were found ineffective, but some neodymium complexesachieved highly selective polymerization of 1,3-butadiene, givingup to 95% of 1,4-cis-polybutadiene albeit with mildactivity. [ABSTRACT FROM AUTHOR]