CO2 Transformation at Controlled Temperature with Lithium Hydroxide Solution and Metallic Lithium

This paper presents a study on CO2 atmospheric transformation which was reacted directly with lithium hydroxide solution and metallic lithium. This solution was obtained through the reaction between metallic lithium and deionized water where hydrogen is produced and by exposing the metal at ambient conditions. In the transformation process, atmospheric CO2 gas reacts directly with LiOH solution, in both cases, the CO2 transformation kinetics was different. For this purpose, reactions between CO2 and LiOH solution were carried out under controlled temperature and the second process only with metallic lithium, which was exposed at room temperature, however, in these two processes lithium carbonate oxide was formed and identified. According to the results, the efficiency in CO2 transformation is a function of temperature value which was variable until completely obtaining the by-product, its XRD characterization indicated the formation only of Li2CO3 in both procedures. Under laboratory conditions lithium compounds selectively reacted with CO2. In the same way, there is an alternative procedure to obtain LiOH and Li2CO3 for different applications in various areas.

Public debate on metallic hydrogen to boost high pressure research

Instead of praises from colleagues,the claim of observation of metallic hydrogen at 495 GPa by Dias and Silvera met much skepticism,and grew into a public debate at the International Conference on High-Pressure Science and Technology,AIRAPT26.We briefly review this debate,and extend the topic to show that this disputation could be an opportunity to benefit the whole high pressure community.

Co-intensification of gold leaching with heavy metals and hydrogen peroxide

Co-intensification was researched to accelerate gold leaching with regards to its electrochemical nature by using anodic intensifiers of heavy metal ions (Pb2+,Bi3+,Tl+,Hg2+ and Ag+) on the basis of hydrogen peroxide assistant leaching on three different types of materials which were classified as a refractory sulphide gold concentrate,an easily leachable sulphide gold concentrate,and a low grade oxide gold ore according to their leaching characteristics.The results showed that,favorable co-intensification effects on the three materials were obtained and leaching time of gold was effectively shortened to no longer than 12 h from 16 to 24 h for hydrogen peroxide assistant leaching.For the five tested heavy metal ions,Bi3+and Tl+ presented co-intensifying effect on all the three materials,and Hg2+ caused co-intensifying effect on both refractory and easily leachable sulphide gold concentrates,and Pb2+ and Ag+ only had co-intensifying effect on the easily leachable sulphide gold concentrate.

Hydrogenated Graphene as Metal-free Catalyst for Fenton-like Reaction

碳的催化剂是金属催化剂的潜在的选择。Graphene 为它的高表面区域和轻重量被付了许多注意。这里， hydrogenated graphene 被 graphene 氧化物的简单 gamma 光线照耀准备了在房间温度的水的暂停。传播电子显微镜，元素分析， X 光检查光电子光谱学，和紫外力的分光光度计研究验证了 graphene 的加氢。同样准备的 hydrogenated graphene 能在水里为器官的染料的象 Fenton 一样降级被用作没有金属的碳的催化剂。

Catalyses of Metals and Their Sulfides in Selective Hydrogenation of 9,10-Diphenylanthracene

Catalytic hydrogenation and hydrocracking of 9,10 diphenylanthracene (9,10 DPA) , used as a coal related model compound, was investigated at a relatively low temperature. The results show that the Fe and Ni mainly catalyze non ipso hydrogenation of 9,10 DPA without sulfur, but selectively promote ipso hydrogenation of 9,10 DPA in the presence of sulfur.

ELECTRONIC STATES AND HYDROGEN EMBRITTLEMENTIN TRANSITION METALS

An electronic approach to the mechanism of hydrogen embrittlement in metals is pre-sented and discussed. Some problems of the mechanism of hydrogen embrittlement are pointed out from an electronic point of view. Electronic structure calculations in a periodically cleaved or slipped lattice are developed in orker to identofy deformation-sensitive electronic states in the absence of hydrogen. The calculational results are given and discussed for a trunsition metal, Pd. Electronic structure calculations in the presence of hydrogen are outlined and hydrogen embrittlement in transition metals is discussed in terms of electronic states.

Electrocatalytic Activity of Ni/C Electrodes Prepared by Metal Vapor Synthesis For Hydrogen Evolution in Alkaline Solution

The metal vapor synthesis (MVS) methed was used to prepare activatedcarbon supported nickel electrode. The electrocatalytic activity of the electrode forhydrogen evolution reaction(HGR) in alkaline solution was studied. Cathodicpolarization curves showed the electrocatalytic activity of Ni/C electrode prepared byMVS method was higher than that of the one prepared by conventional method.

MODIFICATION OF TRANSITION METAL CATIONS TO POLYMER-STABILIZED PLATINUM COLLOIDAL CLUSTERS IN ENANTIOSELECTIVE HYDROGENATION OF METHYL PYRUVATE

Modification of transition metal cations to polymer-stabilized Pt colloidal clusters modified with cinchonidine was studied in enantioselective hydrogenation of methyl pyruvate.Compared to the enantiomeric excess(e.e.)value(71.4%) obtained without the presence of metal cations,obvious e.e.enhancement(up to 82.5%)was resulted from the addition of Zn^(2+) but with a certain decrease in activity.The reaction parameters in the presence of Zn^(2+) were also studied.It was found that the Pt colloidal catalysts in the presence of metal cations performed very differently from that in the absence of metal cations.

EFFECTS OF RARE EARTH METAL ON HYDROGEN BEHAVIOUR IN STEEL 16Mn

The slow tensile tests,dynamic hydrogen charging tensile tests and hydrogen evolution tests after hydrogen charging were used to study the effects of rare earth metal(REM)on hydrogen behaviour in a steel 16Mn(St.52).The ratios of RE/S were chosen as 0,0.7,2.2 and 7.7,respectively.It was shown that the steel with RE/S = 2.2 give a lower hydrogen embrittlement susceptibility than others.The steels without REM can adsorb much more amount of hydrogen than that with REM under the same hydrogen charging conditions.And the amount of adsorbed hydrogen for the foriner can be evolved easier than that for the latter at room temperature,50℃ and 80℃,respectively.The experimental results were explained by the trap theory of hydrogen,the short-circuit diffusion paths in the interfaces between the elongated MnS inclusions and the matrix,and strong ability of REM to adsorb hydrogen.

Addition of cerium and yttrium to ferritic steel weld metal to improve hydrogen trapping efficiency

The applicability of Ce and Y as promising candidate elements to form irreversible traps in weld metal was investigated by thermal desorption spectroscopy(TDS) with gas chromatography(GC). The precise nature of the precipitate particles newly formed in the weld metal by the addition of Ce and Y to a certain alloy system was characterized. Moreover,the hydrogen trapping efficiency expressed as the reduction of the diffusible hydrogen in the weld metal was analyzed. The results showed that the addition of Ce and/or Y to this alloy system led to the formation of a mixed type of(Ce,Ti)-based oxide,(Y,Ni)-based carbide,or(Ce,Y,Ti)-based oxide particles. Because of the high activation energy of the mixed type of particles(≥ 150 k J/mol),the trapping efficiency for hydrogen was considered to be sufficiently high to effectively reduce the diffusible hydrogen content.

Purified oxygenand nitrogen-modified multi-walled carbon nanotubes as metal-free catalysts for selective olefin hydrogenation

Oxygen and nitrogen-functionalized carbon nanotubes （OCNTs and NCNTs） were applied as metal-free catalysts in selective olefin hydro- genation. A series of NCNTs was synthesized by NH3 post-treatment of OCNTs. Temperature-programmed desorption, N2 physisorption, Raman spectroscopy, high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy were employed to characterize the surface properties of OCNTs and NCNTs, aiming at a detailed analysis of the type and amount of oxygen- and nitrogen-containing groups as well as surface defects. The gas-phase treatments applied for oxygen and nitrogen functionalization at elevated temperatures up to 600 ℃ led to the increase of surface defects, but did not cause structural damages in the bulk. NCNTs showed a clearly higher activity than the pristine CNTs and OCNTs in the hydrogenation of 1,5-cyclooctadiene, and also the selectivity to cyclooctene was higher. The favorable catalytic properties are ascribed to the nitrogen-containing surface functional groups as well as surface defects related to nitrogen species. In contrast, oxygen-containing surface groups and the surface defects caused by oxygen species did not show clear contribution to the hydrogenation catalysis.

Scaling law of hydrogen evolution reaction for InSe monolayer with 3d transition metals doping and strain engineering

Recently, two dimensional In Se attracts great attentions as potential hydrogen production photocatalysts.Here, comprehensive investigations on the hydrogen evolution reaction activity of In Se monolayer with3 d transition metal doping and biaxial strain were performed based on the density functional theory.Transition metal dopants significantly increase the bonding strength between H and Se, and then adjust the hydrogen adsorption free energy to 0.02 e V by Zn doping. The enhanced hydrogen evolution reaction activity results from less electron occupying H 1 s-Se 4 pzanti-bonding states, which is well correlated with the pzband center level. Importantly, the universal scalling law was proposed to descript the evolution of hydrogen adsorption free energy including both doping and strain effects. Moreover, with appropriate band alignment, optical absorption, and carriers separation ability, Zn doped In Se monolayer is considered as a promising candidate of visible-light photocatalyst for hydrogen production.

Transition metal nanoparticles supported La-promoted MgO as catalysts for hydrogen production via catalytic decomposition of ammonia

The uniformly dispersed transition metal(Co, Ni and Fe) nanoparticles supported on the surface of La-promoted Mg O were prepared via a deposition-precipitation method for hydrogen production from catalytic decomposition of ammonia. X-ray diffraction, N2 adsorption-desorption, transmission electron microscopy, temperature-programmed reduction and temperature-programmed desorption were used to investigate the structure-activity relation of catalysts in NH3 decomposition. The results show that the strong interaction between active species and support can effectively prevent the active species from agglomerating during ammonia decomposition reaction. In addition, the introduction of La species not only facilitates the adsorption and decomposition of NH3 and desorption of N2, but also benefits the better dispersion of the active species. The prepared catalysts showed very high catalytic activity for ammonia decomposition compared with the same active composition samples that reported previously. Meanwhile, the catalysts showed excellent high-temperature stability and no any deactivation was observed, which are very promising candidates for the decomposition of ammonia to hydrogen.

Hydrogen absorption and desorption in metallic glass and nanocrystalline Zr_(52.5)Cu_(17.9)Ni_(14.6)Ti_5Al_(10) alloy

To illuminate the intrinsic surface activity of Zr52.5Cu17.9Ni14.6Ti5Al10 alloy in its glass and nanocrystalline states,hydrogen absorption and desorption in both states was investigated by gas chromatographic analysis. The results show that the Zr52.5Cu17.9Ni14.6Ti5Al10 alloy in the nanocrystalline state can absorb a larger amount of hydrogen than that in glass state at room temperature after activation. According to the desorption process and surface state,the significant change in absorption induced by crystallization is proposed to result from that the glassy alloy has a higher desorption energy,which can adsorb gas physically and nonselectively,and is difficult to activate,while the nanocrystalline alloy can absorb much hydrogen due to the inter-atomic or intra-atomic electron transfer,which accelerates the kinetics of the catalytic reaction for the dissociation of molecular hydrogen into atomic hydrogen.

Highly Dispersed Pd Nanoparticles Supported on Zr-Doped MgAl Mixed Metal Oxides for 2-Ethylanthraquinone Hydrogenation

In this study,Pd-Mg(Al)-LDH/γ-Al2O3 and Pd-Mg(Al)Zr-LDH/γ-Al2O3 precursors were synthesized by impregnating Na2PdCl4 on Mg(Al)-LDH/γ-Al2O3 and Mg(Al)Zr-LDH/γ-Al2O3,and then the precursors were calcinated and reduced to obtain Pd-Mg(Al)-MMO/γ-Al2O3 and Pd-Mg(Al)Zr-MMO/γ-Al2O3 catalysts.Compared with Pd/γ-Al2O3 catalyst,the hydrogenation efficiency of Pd-Mg(Al)-MMO/γ-Al2O3 and Pd-Mg(Al)Zr-MMO/γ-Al2O3 increased by 15.7%and 24.0%,respectively.Moreover,the stability of Pd-Mg(Al)Zr-MMO/γ-Al2O3 catalyst was also higher than that of Pd/γ-Al2O3.After four runs,the hydrogenation efficiency of Pd/γ-Al2O3 decreased from 12.1 to 10.0 g/L,while that of Pd-Mg(Al)Zr-MMO/γ-Al2O3 decreased from 15.0 to 14.3 g/L.The active aquinones selectivities of all catalysts were almost 99%.The structures of the catalysts were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),N2 adsorption–desorption,inductively coupled plasma-atomic emission spectrometry(ICP-AES),CO chemisorption analysis,transmission electron microscopy(TEM),temperature-programmed reduction with hydrogen(H2-TPR),and X-ray photoelectron spectroscopy(XPS).The results indicate that the improved catalytic performance is attributed to the stronger interaction between Pd and Mg(Al)Zr-MMO/γ-Al2O3,smaller Pd particle size and higher Pd dispersion.This work develops an effective method to synthesize highly dispersed Pd nanoparticles based on the layered double hydroxides(LDHs)precursor.

THE EFFECT OF TRANSITION METAL IONS-IRON ON HYDROGEN PEROXIDE BLEACHING

Hydrogen peroxide bleaching has been extensivelyused in high-yield pulp bleaching. Unfortunately,hydrogen peroxide can be decomposed underalkaline condition, especially when transition metalions exit. Experiments show that the valence oftransition metal ion is also responsible for thedecomposition of hydrogen peroxide.Iron ions are present in two oxidation states, Fe2+ andFe3+. They are both catalytically active to hydrogenperoxide decomposition. Because Fe3+ is brown, itcan affect the brightness of pulp directly, it can alsocombine with phenol, forming complexes which notonly are stable structures and are difficult to beremoved from pulp, but also significantly affect thebrightness of pulp because of their color.Sodium silicate and magnesium sulfate, when usedtogether, can greatly decrease hydrogen peroxidedecomposition. The optimum dosage of sodiumsilicate is about 0.1% (on solution) for Fe2~ and0.25% (on solution) for Fe3~. Adding chelants such asDTPA or EDTA with stabilizers simultaneously canobviously improve pulp brightness. For iron ions, thechelate effect of DTPA is better than that of EDTA.Under acidic conditions, sodium hyposulfite andcellulose can reduce Fe3+ to Fez+ effectively, and pulpbrightness is improved greatly. Adding sodiumthiosulfate simultaneously with magnesium sulfate,sodium silicate, and DTPA to alkaline peroxidesolution can result in higher brightness of pulp.pH is a key parameter during hydrogen peroxidebleaching, the optimum pH value should be 10.5-12.

Hydroxylation of Phenol Catalyzed by Iron Metal-Organic Framework (Fe-BTC) with Hydrogen Peroxide

Liquid phase catalytic hydroxylation of phenol by Fe-containing metal-organic framework, Fe-BTC (BTC = 1,3,5-benzenetricarboxylate) using 30% H2O2 as an oxidant and H2O as solvent showed good activity and stability under mild reaction conditions. Phenol reacts with hydrogen peroxide over Fe-BTC to produce two main products, viz., catechol and hydroquinone. The effect of temperature, time, substrate/hydrogen peroxide mole ratio and amount of catalyst on catalytic performance were studied. The catalyst could be reused four times without losing significant loss of catalytic performance. The crystallinity and structure of catalyst were unchanged during the catalysis reaction, as confirmed by comparison of XRD and SEM of the fresh and reused catalyst. A reaction mechanism is proposed based on the experimental results.

Selective Area Growth and Characterization of GaN Nanorods Fabricated by Adjusting the Hydrogen Flow Rate and Growth Temperature with Metal Organic Chemical Vapor Deposition

CaN nanorods are successfully fabricated by adjusting the flow rate ratio of hydrogen （H2）/nitrogen （N2） and growth temperature of the selective area growth （SAG） method with metal organic chemical vapor deposition （MOCVD）. The SAG template is obtained by nanospherical-lens photolithography. It is found that increasing the flow rate of 1-12 will change the CaN crystal shape from pyramid to vertical rod, while increasing the growth temperature will reduce the diameters of GaN rods to nanometer scale. Finally the CaN nanorods with smooth lateral surface and relatively good quality are obtained under the condition that the H2：N2 ratio is 1：1 and the growth temperature is 1030℃. The good crystal quality and orientation of GaN nanorods are confirmed by high resolution transmission electron microscopy. The cathodoluminescence spectrum suggests that the crystal and optical quality is also improved with increasing the temperature.

Modification of Metal Complex on the StereoselectiveHydrogenation of 2,3-Butanedione

The modification of some metal complexes on Pt/Al2O3 clusters leads to remarkable increases in both the activity and the selectivity for meso-2,3-butanediol in the stereoselectivity hydrogenation of 2,3-butanedione.