다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

The conversion of CO2 with CH4 into liquid fuels and chemicals in a single-step catalytic process that bypasses the production of syngas remains a challenge. In this study, liquid fuels and chemicals (e.g., acetic acid, methanol, ethanol, and formaldehyde) were synthesized in a one-step process from CO2 and CH4 at room temperature (30 °C) and atmospheric pressure for the first time by using a novel plasma reactor with a water electrode. The total selectivity to oxygenates was approximately 50–60 %, with acetic acid being the major component at 40.2 % selectivity, the highest value reported for acetic acid thus far. Interestingly, the direct plasma synthesis of acetic acid from CH4 and CO2 is an ideal reaction with 100 % atom economy, but it is almost impossible by thermal catalysis owing to the significant thermodynamic barrier. The combination of plasma and catalyst in this process shows great potential for manipulating the distribution of liquid chemical products in a given process.

/pdf/one-step-reforming-of-co2-and-ch4-into-high-value-liquid-5ab3isnpwn.pdf

One-Step Reforming of CO2 and CH4 into High-Value Liquid Chemicals and Fuels at Room Temperature by Plasma-Driven Catalysis.

Catalytic transformation of CH4 under a mild condition is significant for efficient utilization of shale gas under the circumstance of switching raw materials of chemical industries to shale gas. Here, we report the transformation of CH4 to acetic acid and methanol through coupling of CH4, CO and O2 on single-site Rh1O5 anchored in microporous aluminosilicates in solution at ≤150 °C. The activity of these singly dispersed precious metal sites for production of organic oxygenates can reach about 0.10 acetic acid molecules on a Rh1O5 site per second at 150 °C with a selectivity of ~70% for production of acetic acid. It is higher than the activity of free Rh cations by >1000 times. Computational studies suggest that the first C–H bond of CH4 is activated by Rh1O5 anchored on the wall of micropores of ZSM-5; the formed CH3 then couples with CO and OH, to produce acetic acid over a low activation barrier. Catalytic transformation of CH4 under mild conditions has implications to shale gas utilization. Here, the authors report the transformation of CH4 to acetic acid through coupling of CH4, CO and O2 on single-site Rh1O5 anchored in microporous aluminosilicates in liquid phase.

/pdf/single-rhodium-atoms-anchored-in-micropores-for-efficient-1mcybpds7g.pdf

Single rhodium atoms anchored in micropores for efficient transformation of methane under mild conditions.

Silver (Ag) and copper (Cu) nanoparticles have shown great potential in variety applications due to their excellent electrical and thermal properties resulting high demand in the market. Decreasing in size to nanometer scale has shown distinct improvement in these inherent properties due to larger surface-to-volume ratio. Ag and Cu nanoparticles are also shown higher surface reactivity, and therefore being used to improve interfacial and catalytic process. Their melting points have also dramatically decreased compared with bulk and thus can be processed at relatively low temperature. Besides, regularly alloying Ag into Cu to create Ag–Cu alloy nanoparticles could be used to improve fast oxidizing property of Cu nanoparticles. There are varieties methods have been reported on the synthesis of Ag, Cu, and Ag–Cu alloy nanoparticles. This review aims to cover chemical reduction means for synthesis of those nanoparticles. Advances of this technique utilizing different reagents namely metal salt precursors, reducing agents, and stabilizers, as well as their effects on respective nanoparticles have been systematically reviewed. Other parameters such as pH and temperature that have been considered as an important factor influencing the quality of those nanoparticles have also been reviewed thoroughly.

Advances of Ag, Cu, and Ag–Cu alloy nanoparticles synthesized via chemical reduction route

Natural gas is envisioned as a primary source of energy and hydrocarbons in the foreseeable future. Though shale gas has recently become abundant, it has two main concerns: its environmental impact and sustainable utilization. The former is the result of recent reports of natural gas emissions and flares into the environment, where it acts as a powerful greenhouse gas, whereas the latter is dictated by the need for efficient hydrocarbon utilization. Modern natural gas processing units that yield clean fuels and feedstock from methane, CH 4 , require extremely large capital investments and are not economical in remote natural gas extraction sites. Single step (direct), non-syngas based catalytic routes of CH 4 conversion to value added products have not been competitive economically and need to be reevaluated in the light of shale gas availability. This perspective discusses general considerations for the desired hydrocarbon products, the thermodynamic limitations involved in a single step conversion of CH 4 and heterogeneous catalytic routes based on high temperatures and oxide based catalysts. We then discuss other catalysts and methods of CH 4 activation that have recently emerged and are conceptually different from metal oxide catalyst based routes, such as those using sulfur or halogens. Lastly, we discuss a possible route of CH 4 monetization beyond the first reactive product (such as ethylene oligomerization into fuels), as well as currently explored photo(electro)chemical routes of CH 4 activation.

CH4 conversion to value added products: Potential, limitations and extensions of a single step heterogeneous catalysis

Possibility of Direct Conversion of CH4 and CO2 to High-Value Products

A systematic theoretical study was performed to investigate methanol synthesis from CO/CO2 hydrogenation and the water-gas-shift (WGS) reaction on Cu(111) and Cu2O(111) surfaces using density functional theory (DFT) and kinetic Monte Carlo (KMC) simulations Specifically, DFT was used to investigate methanol synthesis from CO/CO2 hydrogenation on these surfaces at P = 80 atm, T = 553 K and (CO+ CO2)/H2 = 20/80 The results show that methanol can be synthesized from CO or CO2 hydrogenation and is dependent on the catalyst’s preparation as well as the active site type Further, CO is the main carbon source when the surface is predominantly covered by Cu+ species However, CO2 is the primary carbon source when metallic Cu covers the surface Under the reaction conditions investigated, H2 and CO easily reduce Cu2O to metallic Cu, and the Cu+ species are stabilized by the presence of H2O, CO2, carrier (such as MgO) or alkali metals For this reason, the scale of methanol produced from CO or CO2 hydrogenation depends on the ratio of Cu+/Cu0

Reaction mechanisms of methanol synthesis from CO/CO2 hydrogenation on Cu2O(111): Comparison with Cu(111)

The influence of the liquid environment on the reaction mechanism in slurry reactors has not been fully investigated. In this work, dimethyl ether (DME) synthesis from methanol dehydration over γ-Al 2 O 3 (1 1 0) and AlOOH (1 0 0) in liquid paraffin and in the gas phase is studied using density functional theory combined with the conductor-like solvent model. The liquid paraffin can influence surface relaxation, Mulliken charges, and adsorptive behavior of γ-Al 2 O 3 and AlOOH. For DME synthesis, liquid paraffin does not influence the reaction path over the γ-Al 2 O 3 surface, but influences its activation energy. Liquid paraffin influences the activation energy and also alters the reaction path of DME synthesis over AlOOH

Theoretical studies on the reaction mechanisms of AlOOH- and γ-Al2O3-catalysed methanol dehydration in the gas and liquid phases

Synthesis of AlOOH slurry catalyst and catalytic activity for methanol dehydration to dimethyl ether

Cu nanoparticles have been synthesized by a novel method, where diethanolamine (DEA) is used as reductant, solvent, surface modifier and shape controller. As-obtained nano-copper has been characterized by XRD, SEM, TEM, XPS and FT-IR. The results show that the nano-copper particles are cubic. The well-dispersed copper nanocubes are single crystals and antioxidized. Nanocube is not oxidized when exposed to air at room temperature for a year. The precursor concentration has little effect on the size and morphology of the product. In addition, this method is simple; raw materials are cheap that makes it applicable for large-scale preparation of copper nanocubes.

Zhihua Gao

Papers

Possibility of Direct Conversion of CH4 and CO2 to High-Value Products

Reaction mechanisms of methanol synthesis from CO/CO2 hydrogenation on Cu2O(111): Comparison with Cu(111)

Theoretical studies on the reaction mechanisms of AlOOH- and γ-Al2O3-catalysed methanol dehydration in the gas and liquid phases

Synthesis of AlOOH slurry catalyst and catalytic activity for methanol dehydration to dimethyl ether

Synthesis of Cu nanoparticles for large-scale preparation