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Atomically dispersed cerium species, anchored to high-area alumina by unsaturated penta-coordinated aluminum, strongly interact with atomically dispersed Cu species to provide active centers for water–gas shift reaction (WGSR). The alumina-anchored Ce3+ species stabilize atomically dispersed Cu+ to form Cu+–Ce3+ active complexes and they work synergistically to enhance low-temperature WGSR activity. This work offers alternative approaches to developing low-cost catalysts for the WGSR process. [ABSTRACT FROM AUTHOR]

High transformation of the propane and CO2 reaction to propylene (PDH–CO2) is impelled by the reverse water–gas shift entails strong catalysts toward the reverse water–gas shift (RWGS) as well as propane dehydrogenation (PDH). A series of Co-modified Fe2O3–ZrO2 with proportions of 3–9 wt% (nCoFe–ZrO2) were synthesized using an oxalate coprecipitation method and their catalytic activity for PDH–CO2 at 550 °C was studied. 7CoFe–ZrO2 displayed the highest conversion to both CO2 and propane (37.6% and 47.4%) and propylene yield (38.1%) at a lower apparent activation energy. The interaction between Co species and Fe species and its effects on the active Fe3O4 and the adsorption of propane/CO2 were revealed using XRD, UV-Vis DRS, SEM/TEM, XPS, NH3/CO2/C3H8-TPD, and H2-TPR analysis. With Co-modification, the reduction of Fe2O3 to Fe3O4 was enhanced, which accelerated RWGS in addition to PDH. The key role of the *OOCH intermediate for promoting PDH and RWGS during PDH–CO2 reaction was traced through in situ DRIFTS characterization. [ABSTRACT FROM AUTHOR]

Hydrazones as organometallic equivalents have emerged as a general and sustainable strategy to utilize naturally abundant aldehydes and ketones as feedstocks while only releasing water and nitrogen gas as byproducts. Yet the addition of these carbanion equivalents to carbonyl compounds has been limited to the use of precious metals as catalysts and hazardous solvents under an inert atmosphere. Herein, we report the development of a manganese-based catalyst system for the addition of aldehydes to carbonyl compounds producing secondary and tertiary alcohols with yields of up to 91%. Furthermore, this method has proven robust and reproducible under aqueous and aerobic conditions to employ an earth-abundant metal catalyst, hence advancing hydrazone umpolung chemistry to be more sustainable and operationally simple. [ABSTRACT FROM AUTHOR]

A fundamental understanding of the exact structural characteristics and reaction mechanisms of interface active sites is vital to engineering an energetic metal–support boundary in heterogeneous catalysis. Herein, benefiting from a newly developed high-temperature ion trap reactor, the reverse water–gas shift (RWGS) (CO2 + H2 → CO + H2O) catalyzed by a series of compositionally and structurally well-defined RhnVO3,4− (n = 3–7) clusters were identified under variable temperatures (298–773 K). It is discovered that the Rh5–7VO3,4− clusters can function more effectively to drive RWGS at relatively low temperatures. The experimentally observed size-dependent catalytic behavior was rationalized by quantum-chemical calculations; the framework of RhnVO3,4− is constructed by depositing the Rhn clusters on the VO3,4 "support", and a sandwiched base–acid–base [Rhout−–Rhin+–VO3,4−; Rhout and Rhin represent the outer and inner Rh atoms, respectively] feature in Rh5–7VO3,4− governs the adsorption and activation of reactants as well as the facile desorption of the products. In contrast, isolated Rh5–7− clusters without the electronic modification of the VO3,4 "support" can only catalyze RWGS under relatively high-temperature conditions. [ABSTRACT FROM AUTHOR]

A high-entropy porous spinel oxide [(Co0.2Cr0.2Fe0.2Mn0.2Ni0.2)3O4] was synthesized via a solvothermal method and calcination. Solvothermal conditions yielding homogeneous precursor composites with five metals were optimized. Low-temperature calcination of the amorphous composites at 500 °C for 60 min yielded porous spheres formed by small primary particles, with crystal structures attributed to single-phase spinels. The homogeneity of the five elements in the spheres was verified via scanning transmission electron microscopy and energy-dispersive X-ray spectroscopy analysis. The high-entropy (Co0.2Cr0.2Fe0.2Mn0.2Ni0.2)3O4 spheres exhibited superior catalytic activity and long-term stability for the reverse water–gas shift reaction at 700 °C for at least 15 h. The importance of the Cr component in stabilizing the spinel structure was demonstrated. Mn, Fe, Co, and Ni served as active sites in the reaction. The advantage of solvothermal synthesis for porous high-entropy materials was discussed. [ABSTRACT FROM AUTHOR]

Investigation of catalytic hydrogenation of CO2 to CO via the reverse water-gas shift (RWGS) was undertaken using Ni/SiO2-based catalysts. Among the array of catalysts tested, the Ni/SiO2 catalyst derived from the reduction of silicalite-1-encapsulated, ligand-protected Ni2+ (Ni0.2@S-1-red) exhibited promising performance. This catalyst demonstrated a CO2 conversion rate approaching the equilibrium conversion of RWGS, a selectivity for CO exceeding 99%, and a high space time yield of CO (9.7 mol gNi -1 h-1). The outcomes observed can be attributed to several factors, such as the highly dispersed Ni0 and Niδ+ species, as well as the presence of bridging oxygen of the Ni-O-Si structure, on which CO2 can be adsorbed moderately. The moderately bonded CO2 on Ni0.2@S-1-red allows for the efficient desorption of its reduced intermediate, i.e. *CO, resulting in the generation of gaseous CO at a rapid rate, consequently preventing its deep hydrogenation to CH4. Complementary Density Functional Theory (DFT) calculations were performed and revealed that CO molecules have poor adsorption and higher adsorption energy on the Ni@S-1 surface compared to the S-1 surface. This supports the rapid desorption of *CO and the observed high selectivity of CO. Moreover, the structure-activity correlation analysis further supports the claim of Ni0.2@S-1-red as a promising RWGS catalyst. [ABSTRACT FROM AUTHOR]

Reverse water gas shift (RWGS) can convert CO2 into CO by using renewable hydrogen. However, this important reaction is endothermic and equilibrium constrained, and thus traditionally performed at 900 K or higher temperatures using solid catalysts. In this work, we found that RWGS can be carried out at low temperatures without equilibrium constraints using a redox method called chemical looping (CL), which uses the reduction and oxidation of solid oxide surfaces. When using our developed MGa2Ox (M = Ni, Cu, Co) materials, the reaction can proceed with almost 100% CO2 conversion even at temperatures as low as 673 K. This allows RWGS to proceed without equilibrium constraints at low temperatures and greatly decreases the cost for the separation of unreacted CO2 and produced CO. Our novel gallium-based material is the first material that can achieve high conversion rates at low temperatures in reverse water gas shift using chemical looping (RWGS-CL). Ni outperformed Cu and Co as a dopant, and the redox mechanism of NiGa2Ox is a phase change due to the redox of Ga during the RWGS-CL process. This major finding is a big step forward for the effective utilization of CO2 in the future. [ABSTRACT FROM AUTHOR]

Converting CO2 to valuable chemicals through a variety of thermal, photo-, and electro-catalytic reaction processes will reduce the net CO2 emission and contribute positively to the "net-zero" goal. C1 and C2 products are important chemical feedstocks and can be produced from the effective catalytic conversion of CO2. The key to developing effective CO2 conversion catalysts is an understanding of CO2 interaction and the elementary bond-breaking and formation steps on the active catalysts. Over the past two decades, density functional theory-based approaches have enabled both mechanistic understanding and catalyst design for CO2 activation and conversion. In this article, we review our recent effort in understanding the mechanism of CO2 activation and conversion, focusing on the unique role of the metal/metal oxide interfaces in both thermal and electrochemical catalytic CO2 reduction. We showed that In2O3-based catalysts exhibited a uniquely high methanol selectivity while suppressing CO formation from the reverse water–gas shift reaction. We have also demonstrated that the metal/metal-oxide interfaces can be tuned by selecting an appropriate metal and metal oxide to optimize its activity and selectivity for both thermal- and electro-catalytic reduction of CO2. The oxophilicity of the metal in the metal oxide can be used as a qualitative measure for determining the selectivity towards CH3OH or CH4 in the electro-catalytic reduction of CO2. The studies demonstrated the impact of the density functional theory-based atomic-level approaches in unravelling the reaction mechanism and predicting highly efficient catalysts and catalytic systems. [ABSTRACT FROM AUTHOR]

The key to optimizing energy-consuming catalytic conversions lies in acquiring a fundamental understanding of the nature of the active sites and the mechanisms of elementary steps at an atomically precise level, while it is challenging to capture the crucial step that determines the overall temperature of a real-life catalytic reaction. Herein, benefiting from a newly-developed high-temperature ion trap reactor, the reverse water-gas shift (CO2 + H2 → CO + H2O) reaction catalyzed by the Rhn− (n = 3–11) clusters was investigated under variable temperatures (298–783 K) and the critical temperature that each elementary step (Rhn− + CO2 and RhnO− + H2) requires to take place was identified. The Rh4− cluster strikingly surpasses other Rhn− clusters to drive the catalysis at a mild starting temperature (∼440 K). This finding represents the first example that a specifically sized cluster catalyst that works under an optimum condition can be accurately filtered by using state-of-the-art mass spectrometric experiments and rationalized by quantum-chemical calculations. [ABSTRACT FROM AUTHOR]

The degradation of desiccants is important in designing natural gas conditioning processes. Previous studies have focused on the effect of changes in regeneration gas water content, regeneration temperature and number of thermal cycles. However, less is known about how other components impact the lifespan of desiccants over thousands of thermal cycles. Herein we present results on how desiccant degradation is influenced by CO2 in a process fluid. Increasing the CO2 concentration resulted in less degradation across unsupported zeolite 4A, zeolite 13X and silica gels. Additionally, higher water concentrations in the regeneration gas resulted in a decrease in the degradation at the same CO2 concentration. For zeolite 13X, the surface area and pore volumes were larger in the samples subjected to greater CO2 concentrations. For silica gels, a higher capacity for water adsorption after 5000 thermal swing adsorption cycles was observed in samples with a lower concentration of surface silanol groups. [ABSTRACT FROM AUTHOR]

A new composite material CsPbBr3@HPU-22 was prepared by using {[Zn2(ADDA)2(DMF)(H2O)2]·(DMF)}n (HPU-22) as a carrier to encapsulate CsPbBr3 in channels. The obtained composite material has high sensitivity to water. Under the stimulation of a humid environment or water vapor, the color of the CsPbBr3@HPU-22 product can be seen to turn from yellow to white. In addition, it is necessary to note that the changed color could recover after drying. A study of the mechanism demonstrated that the inter-conversion between CsPbBr3 and CsPb2Br5 is the major reason for this reversible color change during the wetting and drying process. In addition, CsPbBr3@HPU-22 also exhibited high sensitivity to acid–base gases, accompanied by a change in fluorescence color under UV light. The evidence showed that the protonation of DMF molecules might result in the reversible response of CsPbBr3@HPU-22 to acid–base gases. Therefore, the multi-response to water and acid–base gas stimulation gives the CsPbBr3@HPU-22 applications in the field of high-level anti-counterfeiting. [ABSTRACT FROM AUTHOR]

Water management by gas diffusion electrodes is a fundamental aspect of the performance of electrochemical cells. Herein, we introduce the characteristic constrictions size as a descriptor for microporous layers (MPL). This parameter is calculated by volumetric analysis of focused ion beam nanotomography and compared to mercury intrusion porosimetry measurements. [ABSTRACT FROM AUTHOR]

Rapid detection of contaminants for the purpose of sensitive and quantitative monitoring of environmental hazards is an essential first step in realizing the avoidance of human health risks. In this regard, we present a fast and simple electrochemical method of detecting di-n-butyl phthalate (DBP) from river water samples using a phthalic acid group specific aptamer modified on a gold nanoparticle (AuNP) functionalized graphene oxide nano-platelet (GO) and ionic liquid (IL) nanocomposite. Here, the IL/GO nanocomposite allows an enhanced interaction with phthalate esters, thereby increasing the sensitivity of the sensor surface. The proposed sensor showed a wide linear dynamic range from 0.14 pg mL−1 to 0.35 ng mL−1 and from 0.35 ng mL−1 to 7 ng mL−1 with a detection limit of ≤0.042 pg mL−1, which were evaluated using standard, analytical grade DBP; the limit of quantification was determined using different concentrations of DBP in DI water in comparison with gas chromatography-mass spectroscopy (GC/MS) values. The proposed sensor was used to monitor the DBP concentrations in river water samples collected from various locations across South Korea. The quantitative data from the measurements in comparison with standard GC/MS values were then used to ascertain the human health risk posed by the daily consumption of these river waters. [ABSTRACT FROM AUTHOR]

A passivated Au/α-MoC catalyst, containing 2–4 layered Au clusters of 1.6 nm, was re-activated by CH4/H2 at 590 °C, during which the structure of the gold-carbide interface changed considerably. The partially-oxidized surface Mo species were carburized to MoC, while the Au clusters dispersed into smaller ones, accompanied by the coating of carbide thin layers on Au. This restructuring promoted charge transfer from Au to MoC and extended the Au-MoC interfacial perimeter, which was largely responsible for the activity in the low-temperature water-gas shift reaction. [ABSTRACT FROM AUTHOR]

Compound specific isotope analysis (CSIA) provides a valuable tool to identify multiple sources and to elucidate the underlying transformation processes of different organic contaminants in complex environments. Different from conventional isotope ratio mass spectrometry (IRMS) based techniques, a mid-infrared laser based analytical approach is newly developed in this study for gas chromatography (GC) separation and carbon CSIA of aromatic organic pollutants in water. The accuracy and precision of our method are evaluated by determining δ13C values of benzene, toluene, ethylbenzene and 1,2,4-trimethylbenzene dissolved in water. Headspace samples at microgram-per-liter aqueous concentrations are analyzed and the obtained precision is higher than 0.3‰ for all the target compounds. The accuracy of our method is cross validated by comparing with the conventional IRMS measurements, where the differences in δ13C values of the target compounds are within 0.5‰. The validated approach is applied to monitor the temporal trend of the carbon isotopic composition of 1,2,4-trimethylbenzene in drilling fluids collected during horizontal shale drilling processes. The increasing δ13C trend indicates carbon isotope sensitive processes likely caused by subsurface transformations of 1,2,4-trimethylbenzene. To the best of our knowledge, this is the first validated optical carbon CSIA approach proven to be applicable for a wide spectrum of organic compounds. [ABSTRACT FROM AUTHOR]

CeO2-based nanomaterials have received tremendous attention due to their variety of applications. This paper is focused on the recent advances in facet-controlled CeO2-based nanomaterials by the hydrothermal method. CeO2-based nanomaterials with controllable size and exposed facets can be prepared by adjusting the reaction parameters. Moreover, doping and loading metals can improve the oxygen storage capacity (OSC) of CeO2 and its catalytic activity. Various research studies on catalytic applications such as CO oxidation, water–gas shift reaction (WGSR), decomposition of hydrocarbons, and photocatalytic reaction have been carried out to exhibit the high potential of facet-controlled CeO2 nanomaterials. This review will provide readers with various ideas for facet-controlled CeO2-based nanomaterials. [ABSTRACT FROM AUTHOR]

CO2 conversion to CO by reverse water-gas shift using chemical looping (RWGS-CL) can be conducted at lower temperatures (ca. 723–823 K) than the conventional catalytic RWGS (>973 K), and has been attracting attention as an efficient process for CO production from CO2. In this study, Co–In2O3 was developed as an oxygen storage material (OSM) that can realize an efficient RWGS-CL process. Co–In2O3 showed a high CO2 splitting rate in the mid-temperature range (723–823 K) compared with previously reported materials and had high durability through redox cycles. Importantly, the maximum CO2 conversion in the CO2 splitting step (ca. 80%) was much higher than the equilibrium conversion of catalytic RWGS in the mid-temperature range, indicating that Co–In2O3 is a suitable OSM for the RWGS-CL process. [ABSTRACT FROM AUTHOR]

Herein, a new strategy for the direct synthesis of functionalized pyrroles from β-amino alcohols and ynones via ruthenium-catalyzed acceptorless dehydrogenative coupling has been demonstrated. This developed methodology proceeds in an atom- and step-economic fashion together with the merits of broad substrate scope, operational simplicity, and water and hydrogen gas as the sole by-products, which provides an alternative and sustainable way to access functionalized pyrroles. Further, this method was applied to the rapid synthesis of the COX-1/COX-2 inhibitor and boron dipyrromethene derivative successfully. [ABSTRACT FROM AUTHOR]

Single-atom catalysts (SACs) have attracted great attention in heterogeneous catalysis. In this Feature Article, we summarize the recent advances of typical Au and Pt-group-metal (PGM) based SACs and their applications in the water–gas shift (WGS) reaction in the past two decades. First, oxide and carbide supported single atoms are categorized. Then, the active sites in the WGS reaction are identified and discussed, with SACs as the positive state or metallic state. After that, the reaction mechanisms of the WGS are presented, which are classified into two categories of redox mechanism and associative mechanism. Finally, the challenges and opportunities in this emerging field for the collection of hydrogen are proposed on the basis of current developments. It is believed that more and more exciting findings based on SACs are forthcoming. [ABSTRACT FROM AUTHOR]

Iron based catalysts have been widely used in CO2 hydrogenation reactions and phase transformation during hydrogenation has been noted. Herein, iron oxide was observed to be in situ carburized into Fe3C, and Fe3C was identified as the active and stable phase during the reverse water gas shift (RWGS) reaction. Factors such as the reduction degree of iron oxide and reaction temperatures were revealed to affect the phase transformation from iron oxide to Fe3C. The feed gas ratio of H2/CO2 had a decisive effect on the in situ formation of Fe3C and an optimized ratio of 2 was crucial to avoid the excessive oxidation or reduction of carbide. Ex situ synthesized Fe3C via CO carbonization had an inferior catalytic performance compared with the in situ generated Fe3C due to the unexpected but inescapable carbon deposition. [ABSTRACT FROM AUTHOR]

In comparison with the Co analog, small Fe clusters incorporated in a graphene matrix exhibit a photo-assisted increase of 110% in reverse water gas shift CO2 hydrogenation under UV-Vis light irradiation. Available data indicate that the photo-assistance derives from light absorption by the N-doped graphene followed by charge recombination at the Fe clusters, increasing their local temperature. [ABSTRACT FROM AUTHOR]

Puckering transitions of the proline residue for Ac-Pro-X (X = OH, OMe, and NHMe) with trans and cis prolyl peptide bonds were explored along the pseudorotation phase angle using DFT methods in the gas phase and in water. It is observed that the puckering transition proceeds from a down-puckered conformation to an up-puckered one and vice versa through the transition state (TS) with an envelope form having the N atom on top of the envelope structure, although there are some differences in barriers to the puckering transition depending on the C-terminal end group. The relative conformational energies of local minima and TSs for Ac-Pro-X at the CCSD(T), MP2, M06-2X, and DSD-PBEP86-D3BJ levels of theory with various basis sets were assessed against the benchmark CCSD(T)/CBS-limit energies in the gas phase and in water. The double-hybrid DSD-PBEP86-D3BJ/def2-QZVP level of theory exhibited the best performance (RMSD ≈ 0.17 kcal mol−1) against the benchmark CCSD(T)/CBS-limit energies. At all three levels of theory, the barrier height to the down-to-up puckering transition was in the order Ac-trans-Pro-OMe > Ac-trans-Pro-OH > Ac-trans-Pro-NHMe, whereas it was Ac-cis-Pro-NHMe > Ac-cis-Pro-OMe > Ac-cis-Pro-OH in water. From the comparison of the relative free energies of puckered structures and barriers to the puckering transition for Ac-trans-X-OMe (X = 11 Cγ-substituted Pro derivatives) in water, flp and mep residues exhibited a higher preference for down-puckering; and Hyp, Flp, and Mep residues exhibited a higher preference for up-puckering. Hence, the placement of flp/mep and Hyp/Flp/Mep in the X and Y positions of the X–Y-Gly triplet repeat in collagen model peptides, respectively, is expected to enhance the preorganization and thereby the stability of collagen triple helices. [ABSTRACT FROM AUTHOR]

DaltonTransactions An international journal of inorganic chemistry rsc. li/ dalton Volume 53 Number 19 21 May 2024 Pages 8055- 8498 ISSN 1477- 9226 PAPER Kazuya Kobiro et al. Low- temperature synthesis of porous high- entropy ( CoCrFeMnNi) 3 O 4 spheres and their application to the reverse water– gas shift reaction as catalysts [Extracted from the article]

Ni catalysts tend to easily undergo methanation and metal sintering at high temperatures during the CO2 hydrogenation reaction. Herein, Ni2P, a typical kind of transition metal phosphide, had been demonstrated to be efficient for use in the reverse water gas (RWGS) reaction. Under weight hourly space velocity (WHSV) values of 150 000 and 300 000 mL g−1 h−1, the Ni2P/CeO2 catalyst presented a high CO selectivity, better than that of the conventional Ni/CeO2 catalyst. The activity was also well maintained in a 20 h stability test. Detailed physicochemical characterization proved that the moderate adsorption strength of CO2, as well as more strong adsorption active sites for H2 on the Ni2P/CeO2 surface, prevented the CO2 from further hydrogenating to CH4, which accounted for the remarkable CO selectivity and stability of the CO2 RWGS reaction. [ABSTRACT FROM AUTHOR]

A series of Sn-modified CuZnAlSi slurry catalysts were prepared by the complete liquid phase method to perform the synthesis of dimethyl ether (DME) from syngas. The catalysts were characterized by XRD, TEM, H2-TPR, N2-adsorption, NH3-TPD and XPS. The results showed that the slurry catalysts with a suitable amount of Sn significantly suppressed the water gas shift reaction and enhanced the selectivity of DME. The introduction of Sn may improve the Cu dispersion and modulate the acid property, which can increase CO conversion and suppress the formation of hydrocarbons, respectively. The optimized bifunctional catalyst performed 53.47% CO conversion with 82.12% DME selectivity. [ABSTRACT FROM AUTHOR]

In situ generated Sn nanoparticles on fluorine-doped tin oxide act as an electrocatalyst for the CO2 reduction reaction to efficiently and stably produce synthetic gas from water and carbon dioxide with the reaction rate drastically enhanced by the addition of ammonium ions. [ABSTRACT FROM AUTHOR]

5-Hydroxymethylfurfural (HMF) is a natural product derived from the degradation of sugars in e.g. milk, honey and raisins. Recent studies have shown that this compound has several beneficial physiological effects including antioxidant activity. In the present paper, the antiradical properties of 5-HMF were systematically investigated by using the M06-2X/6-311++G(d,p) model chemistry in the gas phase, in water solution and, for a lipid-mimetic environment, in pentyl ethanoate solvent. The thermodynamic and kinetic modelling of the reactions of 5-HMF with a range of reactive oxidative species revealed that 5-HMF scavenges HO˙ and HOO˙ radicals. The overall rate constants for the HO˙ radical scavenging in the gas phase and water and pentyl ethanoate solvents are 2.39 × 1012, 5.92 × 109 and 5.28 × 109 M−1 s−1, respectively, whereas those for the HOO˙ radical scavenging in these environments are low with k = 1.27 × 102, 12.1 and 5.48 M−1 s−1, respectively. The radical adduct formation mechanism plays an important role in the reactions of 5-HMF with HO˙ radicals in all of the studied media. [ABSTRACT FROM AUTHOR]

Owing to the combination of intriguing activity and conductivity, hybrid compositions of layered double hydroxides (LDHs) and carbon-based materials have been extensively and widely applied to evolve oxygen gas during water splitting. Here, a facile in situ nucleation strategy was used to construct ultrafine NiFe-LDH nanosheets monodispersed on a carbon black (CB) substrate. Notably, this work displayed the interfacial impact of combining CB with NiFe-LDHs on electrocatalyst activation. Interestingly, the optimized NiFe-LDHs/CB composite displays a fast activation rate and excellent water oxidation performance on a glassy-carbon electrode (an overpotential of 226 mV at 10 mA cm−2; a Tafel slope of 57 mV dec−1). This is due to the high active area, low impedance and ultra-high active metal atom utilization rate, accelerating charge transfer at the interface during the activation process. More importantly, this work highlights the interfacial charge transfer effect during the activation process and supplies clues for designing electrocatalysts. [ABSTRACT FROM AUTHOR]

Tandem catalysis via methanol intermediate is a promising route for the direct conversion of syngas into aromatics. However, the simultaneous formation of CO2 is a serious problem. Here, we demonstrate that CO2 was formed by the water-gas shift (WGS) reaction (CO + H2O → CO2 + H2) over a ZnO–ZrO2/H-ZSM-5 catalyst, and the net CO2 formation could be inhibited without affecting the formation of aromatics by co-feeding CO2. [ABSTRACT FROM AUTHOR]

Methyl methoxyacetate (MMAc) is a significant chemical product and can be applied as a gasoline and diesel fuel additive. This study aimed to achieve the industrial production of MMAc via dimethoxymethane (DMM) carbonylation. The effects of industrial DMM sources, reaction temperature, water content, pretreatment temperature, reaction pressure and time, the ratio of CO to DMM and recycle times were systematically investigated without any solvent. The conversion of DMM was 99.98% with 50.66% selectivity of MMAc at 393 K, 6.0 MPa reaction pressure, with the ratio of CO to DMM of only 1.97/1. When water was extracted from the DMM reactant, the MMAc selectivity significantly rose to 68.83%. This resin catalyst was reused for more than nineteen times in a slurry phase reactor and continuously performed for 300 h without noticeable loss of activity in a fixed bed reactor, displaying excellent stability. The mixed products were successfully separated by distillation, and 99.18% purity of MMAc was obtained. Therefore, the reported DMM carbonylation to MMAc process has an excellent basis for industrial application. [ABSTRACT FROM AUTHOR]

Hydroxyapatite [Ca10(PO4)6(OH)2, HAP] has P–OH Brønsted acidic sites, Ca2+ Lewis acidic sites, and OH− and O2− basic sites on which acidic and basic gas molecules can be selectively adsorbed, and has no micropore onto which various molecules adsorb regardless of the chemical properties of gas molecules. The interaction between the surface sites and acidic and basic gas and water molecules has been investigated by evaluating the adsorption properties of various molecules on the surfaces of calcium-deficient HAP. The specific adsorption sites were assessed by examining the reversible and irreversible adsorption of NH3, CO2, aldehydes, and water vapor on HAP at the temperature of 298 K, using two HAP samples with different Ca/P ratios, but similar structures and surface areas: Ca-deficient HAP with an extreme lower Ca/P ratio (named P-HAP) and one with a higher Ca/P ratio (named C-HAP). Irreversible adsorption of NH3 on C-HAP is attributed to the adsorption on both Ca2+ Lewis acidic and P–OH Brønsted acidic sites. Irreversible adsorption on P-HAP is attributed to the adsorption on P–OH Brønsted acidic sites only. Irreversible adsorption of CO2 occurred on C-HAP only, and preferentially on OH− basic sites. Acetaldehyde undergoes a catalytic reaction over both OH− basic sites and surface P–OH Brønsted acidic sites at 298 K. Water irreversible adsorption was extensively observed for P-HAP, and water was barely desorbed at low pressures. In situ powder X-ray diffraction showed an asymmetric expansion of the lattice in the [100] direction, indicating that water was incorporated into P-HAP crystals, especially on structural OH− sites. Irreversible adsorption of acidic and basic molecules was therefore less observed on P-HAP than on C-HAP, but P-HAP had considerable irreversible adsorption of water vapor with associated asymmetric lattice expansion. The incorporation of water vapor was first observed and could be useful to improve adsorption or catalytic performance with the mediation of water vapor and/or hydration. [ABSTRACT FROM AUTHOR]

Herein, (VO)2P2O7 nanosheets function as a highly-active electrocatalyst for the hydrogen evolution reaction with an ultralow overpotential of 30 mV at 10 mA cm−2 in basic media, being close to Pt/C. Furthermore, as a bifunctional electrocatalyst, (VO)2P2O7 not only exhibits high activity but also good stability for overall water splitting. [ABSTRACT FROM AUTHOR]

Hierarchical MIL-88B-on-MOF-5 octapods were synthesized via a mechanism involving phase-competition-driven growth (PCDG). Dramatically different morphologies (nanocubes, octapods, flowers) were also produced by controlling the phase competition between MIL-88B and MOF-5. The octapod MOFs showed a high catalytic performance for the reverse water–gas shift (RWGS) reaction. [ABSTRACT FROM AUTHOR]

The first nickel-catalysed dehydrogenative coupling of primary alcohols and ethylene glycol with aromatic diamines for selective synthesis of mono- and di-substituted benzimidazoles and quinoxalines is reported. The earth-abundant, non-precious and simple NiCl2/L1 system enables the synthesis of N-heterocycles releasing water and hydrogen gas as byproducts. Mechanistic studies involving deuterium labeling experiments and quantitative determination of hydrogen gas evaluation were performed. [ABSTRACT FROM AUTHOR]

The production of hydrogen from fossil fuels by steam reforming/water gas shift can be enhanced by separating the reaction byproduct, CO2, within the reactor as it is produced. Such a separation-enhanced reaction not only has higher conversion efficiency, but can also be considered a greener process which produces high-purity hydrogen with little CO2contamination. Supported ionic liquid membranes may be able to achieve this separation task since they are known to have high CO2and low H2solubilities. In this study, the 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide family of ionic liquids has been selected for this purpose, based on limited literature data. The solubilities of major reaction gases, namely CO2, H2, CO, and CH4, in 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide are compared to one another. In addition, the solubilities of CO2and H2in 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide are compared. The results indicate, from a thermodynamic point of view, the possibility of using this family of ionic liquids as separation membranes with practical CO2/H2selectivities. [ABSTRACT FROM AUTHOR]

Glycerol can be effectively converted to synthesis gas (selectivity higher than 80%) with small amounts of water or no water using plasmas at low temperature and atmospheric pressure, without external heating. [ABSTRACT FROM AUTHOR]

An atomic layer epitaxy technique was used to produce nanoscale 2.9–3.4 nm copper particles supported on silica, and the nanoscale Cu/SiO2catalysts can show surprisingly high activity for the water gas shift reaction, in comparison with the 5.6 wt% Pt/SiO2and 10.3 wt% Cu/SiO2prepared by the impregnation method. [ABSTRACT FROM AUTHOR]