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The effect of iron promoter on the catalytic properties of Rh-Mn-Li/SiO2 catalyst in the synthesis of C2 oxygenates from syngas was investigated by means of the following techniques: CO hydrogenation reaction, temperature-programmed reduction (TPR), temperature-programmed desorption and reaction of adsorbed CO (CO-TPD and TPSR) and pulse adsorption of CO. The results showed that the addition of iron promoter could improve the activity of the catalysts. Unexpectedly, the yield of C2 oxygenates increased greatly from 331.6 up to 457.5 g/(kg h) when 0.05% Fe was added into Rh-Mn-Li/SiO2 catalyst, while no change in the selectivity to C2 oxygenates was observed. However, the activity and selectivity of C2 oxygenates were greatly decreased if the Fe amount exceeded 1.0%. The existence of a little iron decreased the reducibility of Rh precursor, while the reduction of Fe component itself became easier. CO uptake decreased with increasing the quantity of Fe addition. This phenomenon was further confirmed by CO-TPD results. The CO-TPD and TPSR results showed that only the strongly adsorbed CO could be hydrogenated, while the weakly adsorbed CO was desorbed. We propose that Fe is highly dispersed and in close contact with Rh and Mn; such arrangements were responsible for the high yield of C2 oxygenates. [Copyright &y& Elsevier]

[Display omitted] • Mn-doped spinels Co 1-x Mn x Al 2 O 4 synthesized with sol-gel technique were first time evaluated as FTS catalyst supports. • Lattice Mn doping caused the formation of nanoscale lattice defects and the exposure of high index face on grain surface. • Lattice defects and the high index face on grain surface improved the dispersity of loaded metal Co. • Mn-doped spinels Co 1-x Mn x Al 2 O 4 were found more capable than CoAl 2 O 4 for CO adsorption. • The influence of lattice doped Mn was different from impregnated Mn on the properties of the catalysts. Mn-doped spinel oxides CoAl 2 O 4 marked as CMA-m (m = Co/Mn atom ratio) herein were synthesized and evaluated for the first time as supports of Co-based Fischer-Tropsch synthesis (FTS) catalysts. HAADF-STEM images showed that Mn doping caused more crystal defects on the surface of CMA-m grains, which may provide more attachment sites for cobalt loading, leading to much smaller Co0 particle size of 15Co/CMA-m than that of 15Co/CoAl 2 O 4. Data of H 2 /CO chemisorption showed that the interaction of highly dispersed Co0 with lattice Mn-doped CMA-m grain has a promotive effect on CO adsorption capability. FTS evaluation results demonstrate that 15Co/CMA-20 showed the highest CO conversion, C 5+ selectivity and C 5+ STY, benefiting from its high Co0 dispersion and CO chemisorption capability as a result of suitable Mn doping into the lattice of CoAl 2 O 4 , which was confirmed very different from the influence of impregnated Mn oxide over CoAl 2 O 4. [ABSTRACT FROM AUTHOR]

• Surface oxygen groups of activated carbon-based carrier can be cleansed by H 2 treatment and regenerated by a following oxidation procedure. • Increasing the concentration of the surface oxygen groups of activated carbon-based carrier can effectively increase the FTS activity and C 5+ selectivity. • Oxygen-rich surface can decrease the reduction temperature of Co oxides, facilitate the dispersion of Co NPs, decrease the Co particle size and promote the H 2 /CO uptake. Surface oxygen groups of carbon materials has been validated to be necessary for the synthesis of supported catalysts. Herein we report that the activity and selectivity of activated carbon-based material supported Co catalysts can be tuned by modifying the surface oxygen group concentration. As the groups were cleansed by H 2 at 1173 K, the FTS activity dropped from 8.4 to 4.0 mmol CO/(gcat∙h). Whereas a following oxidation procedure could restore the FTS activity by regenerating the groups. Among which the HNO 3 treatment exhibited the best effect with a remarkable elevation of activity (from 4.0 to 13.6 mmol CO/(gcat∙h)) and C 5+ /ROH combined selectivity (64.9 C%). Characterization methods proved that the rationale behind which should be attributed to the increased Co dispersion/reduction degrees and CO/H 2 uptakes facilitated by the surface oxygen groups, and it exhibited that the activity of FTS increased as the surface oxygen group concentration and acidity were elevated. [ABSTRACT FROM AUTHOR]

The architecture of magma plumbing systems plays a fundamental role in volcano eruption and evolution. However, the precise configuration of crustal magma reservoirs and conduits responsible for supplying eruptions are difficult to explore across most active volcanic systems. Consequently, our understanding of their correlation with eruption dynamics is limited. Axial Seamount is an active submarine volcano located along the Juan de Fuca Ridge, with known eruptions in 1998, 2011, and 2015. Here we present high-resolution images of P-wave velocity, attenuation, and estimates of temperature and partial melt beneath the summit of Axial Seamount, derived from multi-parameter full waveform inversion of a 2D multi-channel seismic line. Multiple magma reservoirs, including a newly discovered western magma reservoir, are identified in the upper crust, with the maximum melt fraction of ~15-32% in the upper main magma reservoir (MMR) and lower fractions of 10% to 26% in other satellite reservoirs. In addition, a feeding conduit below the MMR with a melt fraction of ~4-11% and a low-velocity throat beneath the eastern caldera wall connecting the MMR roof with eruptive fissures are imaged. These findings delineate an asymmetric shallow plumbing system beneath Axial Seamount, providing insights into the magma pathways that fed recent eruptions., (© 2024. The Author(s).)

Supported metal clusters comprising of well-tailored low-nuclearity heteroatoms have great potentials in catalysis owing to the maximized exposure of active sites and metal synergy. However, atomically precise design of these architectures is still challenging for the lack of practical approaches. Here, we report a defect-driven nanostructuring strategy through combining defect engineering of nitrogen-doped carbons and sequential metal depositions to prepare a series of Pt and Mo ensembles ranging from single atoms to sub-nanoclusters. When applied in continuous gas-phase decomposition of formic acid, the low-nuclearity ensembles with unique Pt 3 Mo 1 N 3 configuration deliver high-purity hydrogen at full conversion with unexpected high activity of 0.62 mol HCOOH mol Pt -1 s -1 and remarkable stability, significantly outperforming the previously reported catalysts. The remarkable performance is rationalized by a joint operando dual-beam Fourier transformed infrared spectroscopy and density functional theory modeling study, pointing to the Pt-Mo synergy in creating a new reaction path for consecutive HCOOH dissociations., (© 2023. The Author(s).)

Fischer-Tropsch synthesis (FTS), which provides a green route to the production of clean fuels and fine chemicals, represents some significant applications of catalytic materials and processes in the chemical industry. FTS reactions show a diversity of mechanisms, involve various catalytic materials, and offer options for continuous investigation. Cobalt-based catalysts have been widely used for Fischer-Tropsch synthesis both in academia and in industry. This mini-review will focus on relevant research achievements in cobalt-based FTS catalysts by our group in the Dalian Institute of Chemical Physics (DICP). Specific contents will include the development of Co/Co 2 C-based nano-catalysts (i) for the highly selective synthesis of clean fuels over Co-based catalysts supported by carbon materials and (ii) for the synthesis of linear α-alcohols and olefins over Co-Co 2 C-based catalysts supported by carbon materials. The direct synthesis of linear α-alcohols from syngas using a Co-Co 2 C/AC catalyst is highlighted. The innovative work of FTS using activated carbon (AC)-supported Co/Co 2 C-based nano-catalysts could bring some insight into new FTS catalyst designs.

A P-modified Co/SiO 2 catalyst was reported for the first time in the selective hydrogenation of dimethyl oxalate (DMO) to methyl glycolate (MG) reaction and the synthesized Co 8 P/SiO 2 exhibited 94.6% conversion of DMO and 88.1% selectivity to MG during a 300 h continuous test. The doping element of P in the catalyst was indispensable and played an important role in improving the catalytic performance of the Co/SiO 2 catalyst.

The importance of a low-viscosity asthenosphere underlying mobile plates has been highlighted since the earliest days of the plate tectonics revolution. However, absolute asthenospheric viscosities are still poorly constrained, with estimates spanning up to 3 orders of magnitude. Here we follow a new approach using analytic solutions for Poiseuille-Couette channel flow to compute asthenospheric viscosities under the Caribbean. We estimate Caribbean dynamic topography and the associated pressure gradient, which, combined with flow velocities estimated from geologic markers and tomographic structure, yield our best-estimate asthenospheric viscosity of (3.0 ± 1.5)*10 18 Pa s. This value is consistent with independent estimates for non-cratonic and oceanic regions, and challenges the hypothesis that higher-viscosity asthenosphere inferred from postglacial rebound is globally-representative. The active flow driven by Galapagos plume overpressure shown here contradicts the traditional view that the asthenosphere is only a passive lubricating layer for Earth's tectonic plates.

Laboratory experiments and geodynamic simulations demonstrate that poloidal- and toroidal-mode mantle flows develop around subduction zones. Here, we use a new 3-D azimuthal anisotropy model constructed by full waveform inversion, to infer deep subduction-induced mantle flows underneath Middle America. At depths shallower than 150 km, poloidal-mode flow is perpendicular to the trajectory of the Middle American Trench. From 300 to 450 km depth, return flows surround the edges of the Rivera and Atlantic slabs, while escape flows are inferred through slab windows beneath Panama and central Mexico. Furthermore, at 700 km depth, the study region is dominated by the Farallon anomaly, with fast axes perpendicular to its strike, suggesting the development of lattice-preferred orientations by substantial stress. These observations provide depth-dependent seismic anisotropy for future mantle flow simulations, and call for further investigations about the deformation mechanisms and elasticity of minerals in the transition zone and uppermost lower mantle.

We constructed a three-dimensional azimuthally anisotropic model of Europe and the North Atlantic Ocean based on adjoint seismic tomography. Several features are well correlated with historical tectonic events in this region, such as extension along the North Atlantic Ridge, trench retreat in the Mediterranean, and counterclockwise rotation of the Anatolian Plate. Beneath northeastern Europe, the direction of the fast anisotropic axis follows trends of ancient rift systems older than 350 million years, suggesting "frozen-in" anisotropy related to the formation of the craton. Local anisotropic strength profiles identify the brittle-ductile transitions in lithospheric strength. In continental regions, these profiles also identify the lower crust, characterized by ductile flow. The observed anisotropic fabric is generally consistent with the current surface strain rate measured by geodetic surveys.