Synthesis and Catalytic Application of Ru-Deposited Magnetic nanoparticles for the selective hydrogenation of CO2 gas

: In this report, a hybrid terpyridine (tpy) ligand functionalized with magnetic support was synthesized to obtain well-dispersed Ru NPs with a 2.0±0.5 nm mean size. This material was further analyzed using different analytical techniques before utilizing it as a catalyst for the CO¬2 hydrogenation reaction. A noticeable application of Ru-deposited magnetic nanoparticles as catalysts was observed during the CO2 hydrogenation. We successfully synthesized the formic acid with a high TON value under high-pressure reaction conditions. Easy recovery of the catalyst under the applied magnetic field helped us to reuse the catalyst up to 6 times with good TON and TOV value.

High-pressure reaction profiles and activation volumes of 1,3-cyclohexadiene dimerizations computed by the extreme pressure-polarizable continuum model (XP-PCM)

Quantum chemical calculations are reported for the thermal dimerizations of 1,3-cyclohexadiene at 1 atm and high pressures up to 6 GPa. Previous experiments [Klärner et al. Angew. Chem. Int. Ed. 1986, 25, 108], based on measured activation energies and activation volumes, suggested concerted mechanisms for the formation of the endo [4+2] cycloadduct and a [6+4]-ene adduct, and stepwise mechanisms for the formation of the exo [4+2] cycloadduct and two [2+2] cycloadducts. Computed activation enthalpies (ωB97XD, CCSD(T) and SC-NEVPT2) of plausible dimerization pathways at 1 atm agree well with the experiment activation energies and the values from previous calculations [Ess et al. J. Org. Chem. 2008, 73, 7586]. High-pressure reaction profiles, computed by the recently-developed extreme pressure-polarizable continuum model (XP-PCM), show that the reduction of reaction barrier is more profound in concerted reactions than in stepwise reactions, which is rationalized on the basis of the volume profiles of different mechanisms. A clear shift of the transition state towards the reactant by high pressure is revealed for the [6+4]-ene reaction by the calculations. The computed activation volumes by XP-PCM agree excellently with the experimental values, confirming the existence of competing mechanisms in the thermal dimerizations of 1,3-cyclohexadiene.

Crystallite Size on Micromechanical Characteristics of WO3 Microparticles

This study evaluated the relationship between crystallite size and micromechanical characteristics of micrometersized monoclinic WO3 particles. To avoid the existence of other parameters in the measurement (such as impurities and porous structure in the particle), micrometer WO3 particles were prepared using a direct heat treatment of ultrapure micrometer-sized ammonium tungstate powders. The crystallite size was controlled independently in constant WO3 particle outer diameters to obtain a precise measurement result. The mechanical properties, i.e., hardness and Young’s modulus, were measured by load-controlled nanoindentation test on the singular WO3 particles. The force and displacement relationship data was plotted and analyzed to obtain the relationship between crystallite size and mechanical properties. The results revealed that the micromechanical properties of WO3 particles were strongly dependent on the crystallite size. The hardness and Young’s modulus values increased more than three times when increasing the crystallite size to about 40 nm. The study was completed with a proposed mechanism of crack propagation inside the particle due to static load. The study demonstrates the important role of crystallite size in determining the micromechanical characteristics of WO3 particles. The result is useful especially when utilizing WO3 microparticles for various processes involving extreme conditions, such as high pressure reaction.

Massive carbon storage in convergent margins initiated by subduction of limestone

Remobilization of sedimentary carbonate in subduction zones modulates arc volcanism emissions and thus Earth’s climate over geological timescales. Although limestones (or chalk) are thought to be the major carbon reservoir subducted to subarc depths, their fate is still unclear. Here we present high-pressure reaction experiments between impure limestone (7.4 wt.% clay) and dunite at 1.3–2.7 GPa to constrain the melting behaviour of subducted natural limestone in contact with peridotite. The results show that although clay impurities significantly depress the solidus of limestone, melting will not occur whilst limestones are still part of the subducting slab. Buoyancy calculations suggest that most of these limestones would form solid-state diapirs intruding into the mantle wedge, resulting in limited carbon flux to the deep mantle (< ~10 Mt C y−1). Less than 20% melting within the mantle wedge indicates that most limestones remain stable and are stored in subarc lithosphere, resulting in massive carbon storage in convergent margins considering their high carbon flux (~21.4 Mt C y−1). Assimilation and outgassing of these carbonates during arc magma ascent may dominate the carbon flux in volcanic arcs.

Simulation Experiment of TSR Promotes Cracking of Coal Generation H2S

Thermochemical sulfate reduction (TSR) is one of the main contributors to the formation of hydrogen sulfide (H2S) in coal seam strata. Four reaction systems (coal, coal+water, coal+water and MgSO4, and coal+water and MgSO4 and AlCl3) were selected and simulated from 250°C to 600°C with eight temperature steps using a high-temperature and high-pressure reaction device, and the evolution characteristics of the gaseous products of hydrocarbons (methane, C2-5) and nonhydrocarbon gases (CO2, H2, and H2S) were studied. Thermal simulation experiments showed that the TSR led to the reduction of heavy hydrocarbons, and the presence of salts accelerated the evolution of hydrocarbons; SO42-, Al3+, and Mg2+ had a certain promoting effect on the TSR, which increased the total amount of alkane gas, H2S, and CO2 production. Improving the salinity of the reaction system can promote the occurrence of TSR, and water plays a key role in hydrocarbon generation evolution and the TSR.

Kinetika Reaksi Hidrogenasi Ester Lemak Menjadi Alkohol Lemak Dengan Katalis Tembaga- Mangan

Fatty alcohol (FAOH) can be produced by hydrogenating of fatty acid methyl ester (FAME) using the copper-based catalyst. Copper-Chrom (Cu-Cr) is the best catalyst for high-pressure reaction condition, which is copper (Cu) as the main active component and chrom (Cr) as a promoter. Since Cr is feared to be toxic, one of the best replacement candidates is manganese (Mn). The research aims is to find the kinetic equation of hydrogenation FAME to FAOH using a Cu-Mn commercial catalyst. FAME with methyl laurate and methyl myristate as the main compounds is used as feedstock. The main products are lauryl alcohol and myristyl alcohol. The reaction was carried out in an isothermal continuous fixed bed reactor under conditions of temperature 220 – 240 oC, pressure 50 bar, and liquid hourly space velocity (LHSV) 5-12.5 hr-1. The kinetic equation is determined using the power law model. The FAME hydrogenation on copper - manganese catalyst is the half order reaction. The activation energy value is 86.32 kJ/mol and the Arrhenius constant value is 5.87x106 M0.5/s.