Synthesis of lanthanide β-diketonates by solid state reaction at low heating temperature

Solid state reactions between β-diketones (HPMBP, HDBM) and LnAc₃ · xH₂O(La,Nd:x=3/2; Tb:x=4) have been investigated at low heating temperature. Pure compounds of Ln(PMBP)₃ and Ln(DBM)₃ are obtained by solid state reaction, and characterized by elemental analysis, infrared radiation (IR), X-ray diffraction (XRD) and photoacoustic spectra. The solid state reaction properties of β-diketones and their influences on the structures of products are discussed. Project supported by the National Natural Science Foundation of China (29475209)     

Low-Temperature Selective Catalytic Reduction of NO with NH<Subscript>3</Subscript> over Fe–Ce–O<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> Catalysts

In this study, we used a simple impregnation method to prepare Fe–Ce–O _x catalysts and tested them regarding their low-temperature (200–300 °C) selective catalytic reduction (SCR) of NO using NH₃. We investigated the effects of Fe/Ce molar ratio, the gas hourly space velocity (GHSV), the stability and SO₂/H₂O resistance of the catalysts. The results showed that the FeCe(1:6)O _x (Ce/Fe molar ratio is 1:6) catalyst, which has some ordered parallel channels, exhibited good SCR performance. The FeCe(1:6)O _x catalyst had the highest NO conversion with an activity of 94–99% at temperatures between 200 and 300 °C at a space velocity of 28,800 h^?1. The NO conversion for the FeCe(1:6)O _x catalyst also reached 80–98% between 200 and 300 °C at a space velocity of 204,000 h^?1. In addition, the FeCe(1:6)O _x catalyst demonstrated good stability in a 10-h SCR reaction at 200–300 °C. Even in the presence of SO₂ and H₂O, the FeCe(1:6)O _x catalyst exhibited good SCR performance.     

Study on hydrogen sulfide removal based on bench-scale experiment by bio-trickling filter

A bench-scale experiment for control of hydrogen sulfide (H2S) emissions was carried out continuously for nearly four months by using bio-trickling filter packed with ZX01 stuffing. The results suggested that the bio-trickling filter had proven excellent performance over substantial operational periods. Removal efficiency of H2S was nearly 100% when volumetric loading of the bio-trickling filter varied from 0.64 g/(m3·h) to 38.20 g/(m3·h) and metabolism products of H2S were mainly composed of SO42–. When inlet concentration of H2S was 250 mg/m3, the optimum gas retention time was 30 s and the optimum spray water flow rate was 0.005 9~0.012 L/(cm2·h). The bio-trickling filter had good ability to resist shock of high volumetric loading, and was not blocked during experiments for nearly four months during which resistance was maintained at relatively lower value, so that the bio-trickling filter need not carry out back washing frequently and can be operated steadily for long-term.     

Solubilities of 2-naphthalenesulfonic acid monohydrate and sodium 2-naphthalenesulfonate in sulfuric acid solution and their application for preparing sodium 2-naphthalenesulfonate

The solubilities of 2-naphthalenesulfonic acid monohydrate and sodium 2-naphthalenesulfonate in sulfuric acid solutions were measured at temperatures ranging from 278.15 to 338.15 K by using a dynamic method. The concentration of sulfuric acid solution ranged from 0 to 80wt%,. The solubilities of 2-naphthalenesulfonic acid monohydrate and sodium 2-naphthalenesulfonate increased with temperature, and both of them were the lowest at 70wt %, of sulfuric acid solution(w~0_3 =0.70)while the highest in pure water. The solubility data were correlated by the modified Apelblat equation. Based on the solubility difference between 2-naphthalenesulfonic acid monohydrate and sodium 2-naphthalenesulfonate, a new technique in which sodium sulfate was used to replace sodium sulfite in the neutralization reaction was developed. The suitable mole ratio of H_2O to Na_2SO_4 in the neutralization reaction was 80∶1, and that of 2-naphthalenesulfonic acid monohydrate to Na_2SO_4 was 3.2∶1. The material balance under the suitable mole ratios was given and discussed.     

Study of transport behavior for Fe-doping La<Subscript>0.67</Subscript>Ca<Subscript>0.33</Subscript>MnO<Subscript>3</Subscript> perovskite manganese

Systematic studies of the transport properties of La_0.67Ca_0.33Mn_1?xFe _x O₃ (x=0–0.3) systems showed that with increasing Fe-doping contentx the resistance increases and the insulator-metal transition temperature moves to lower temperature. For small doping content, the transport property satisfies metal transport behavior below the transition temperature, and above the transition temperature it satisfies the small polaron model. This behavior can be explained by Fe³⁺ doping, which easily forms Fe³⁺?O^2??Mn⁴⁺ channel, suppressing the double exchange Mn³⁺?O^2??Mn⁴⁺ channel and enhancing the spin scattering of Mn ions induced by antiferromagnetic clusters of Fe ions.     

Preparation and photocatalytic activity of BiOBr/TiO<Subscript>2</Subscript> heterojunction nanocomposites

An efficient visible-light-responsive BiOBr/TiO₂ heterojunction nanocomposite was fabricated successfully using in-situ depositing technique at room temperature by introducing BiOBr onto the surface of TiO₂ nanobelts pre-prepared by hydrothermal reaction and etched with H₂SO₄. The obtained particles were characterized by XRD, SEM, TEM, XPS, UV-Vis DRS and PL techniques. BiOBr/TiO₂ heterojunction nanocomposites with different mass ratios of m(BiOBr)/m(TiO₂) were discussed in order to get the best photocatalytic activity, and BiOBr/TiO₂-1.0 was proved to be the optimal mass ratio. BiOBr/TiO₂-1.0 exhibited excellent photocatalytic activity in the degradation of RhB compared with TiO₂ nanobelts, pure BiOBr and the mechanical mixture of TiO₂ nanobelts and BiOBr. At last, a possible mechanism of photocatalytic enhancement was proposed.     

Preparation of SO4^2-/TiO2-La2O3 solid superacid and its catalytic activities in acetalation and ketalation

SO4^2- / TiO2-La2O3, a novel solid superacid, was prepared and its catalytic activities at different synthetic conditions are discussed with esterification of n-butanoic acid and n-butyl alcohol as probing reaction. The optimum conditions have also been found, mole ratio of n（La^3＋）：n（Ti^4＋） is 1：34, the soaked consistency of H2SO4 is 0.8 tool/L, the soaked time of HESO4 is 24 h, the calcining temperature is 480 ℃, the calcining time is 3 h. Then it was applied in the catalytic synthesis often important ketals and acetals as catalyst and revealed high catalytic activity. Under these conditions on which the molar ratio of aldehyde/ketone to glycol is l： 1.5, the mass ratio of the catalyst used in the reactants is 0.5%, and the reaction time is 1.0 h, the yields of ketals and acetals can reach 41.4%-95.8%.     

Structure and Magnetic Properties of Fe1-xCx Solid Solution Prepared by Mechanical Alloying

Supersaturated solid solutions Fe1-xCx （0≤x≤0.9 ） of wide composition range have been prepared by mechanical alloying process. Nanocrystalline phase was formed for 0 ≤ x ≤ 0.67 and a large grain phase for 0.75 ≤ x ≤ 0.9. The large fraction of graphite volume puts off formation of nanocrystalline phase for high carbon content. In the large grain phase, magnetization follows simple magnetic dilution, and eoereivity He is mainly due to dissolution of carbon at grain boundaries. In the nanocrystalline phase the alloying effect of carbon is revealed by a distinct reduction of average magnetic moment. The increasing lattice constant with increasing carbon content is observed for x ≤ 0.5, suggesting that the high carbon concentration may enhance diffusion of carbon into the Fe lattice. It shows a discontinuity in the Hc variation with a grain size D of nanocrystalline phase. For small grain D below the critical value, Hc increases with D. For a large grain D, Hc decreases with increasing D. The solubility limit of carbon in a-Fe extended by nanocry- stalline phase formation is discussed.     

Chemically processed Nb-doped SrTiO3 films and properties

Homogeneous, crack-free SrNb_xTi_1−x O₃ thin films on (110) silicon substrates were successfully fabricated by sol-gel processing. The optimum route and conditions were systematically investigated. Sr(OAc)₂ glacial acctic acid solution, after being refluxed and reacted with tartrate, formed Sr(OAc)₂(C₄H₆O₆)₂; Ti(OBu)₄ formed Ti(OAc)_4−x (AcAc)_x after having the ligand partially exchanged with AcAc, while Nb(OC₂H₅)₅ formed (OAc)₂Nb(AcAc) (C₄H₆O₆) by exchanging of ligand in glacial acetic acid with (CH₃CO)₂O. All the metal species after undergoing partial hydrolysis and polymerization with hydroxyl or oxygen, formed SrNb_xTi_1−x O₁₃ cluster sol. Methyl cellulose (MCL) caused SrNb_xTi_1−x O₃ sol to have polymeric structure and easily form films. SrNb_xTi_1−x O₃ films with perovskite were subsequently formed after being annealed at 650∼750 °C for 60 min in 25% N₂+75% H₂ (volume ratio) atmosphere. Resistivity of the SrNb_0.1Ti_0.9O₃ films at room temperature was 64 μω·cm, a particular T ² temperature dependence of the resistivity, from 25 K up to room temperature, was observed. Project (No. 2002CB613305) supported by the National Basic Research Program (973) of China     

Maize seed coatings and seedling sprayings with chitosan and hydrogen peroxide: their influence on some phenological and biochemical behaviors

Objective:To evaluate the effect of chitosan(CH) and hydrogen peroxide(H2O2) seed coatings and seedling sprinklings on two different maize varieties by measuring their phenology,the H2O2 presence,the catalase(CAT) activity,and the protein quantity.Methods:Seven groups of ten seeds for each maize variety were treated with CH(2%(20 g/L) and 0.2%(2 g/L)) or H2O2(8 mmol/L) by coating,sprinkling,or both.Germination and seedling growth were measured.One month after germination,the presence of H2O2 in seedlings in the coated seed treatments was evaluated.Protein content and CAT activity were determined under all treatments.Results:H2O2 seed coating enhanced the germination rate and increased seedling and stem length in the quality protein maize(QPM) variety.Seedlings had a higher emergence velocity under this treatment in both varieties.CH and H2O2 sprinklings did not have an effect on seedling phenology.Exogenous application of H2O2 promoted an increase of endogenous H2O2.CH and H2O2 seedling sprinkling increased the protein content in both maize varieties,while there was no significant effect on the CAT activity of treated seeds and seedlings.Conclusions:CH and H2O2 enhance some phenological and biochemical features of maize depending on their method of application.     

Performance of biotrickling filters for hydrogen sulfide removal under starvation and shock loads conditions

In the industrial operation of biotrickling filters for hydrogen sulfide (H₂S) removal, shock loads or starvation was common due to process variations or equipment malfunctions. In this study, effects of starvation and shock loads on the performance of biotrickling filters for H₂S removal were investigated. Four experiments were conducted to evaluate the changes of biomass and viable bacteria numbers in the biotrickling filters during a 24-d starvation. Compared to biomass, viable bacteria numbers decreased significantly during the starvation, especially when airflow was maintained in the absence of spray liquid. During the subsequent re-acclimation, all the bioreactors could resume high removal efficiencies within 4 d regardless of the previous starvation conditions. The results show that the re-acclimation time, in the case of biotrickling filters for H₂S removal, is mainly controlled by viable H₂S oxidizing bacteria numbers. On the other hand, the biotrickling filters can protect against shock loads in inlet fluctuating H₂S concentration after resuming normal operation. When the biotrickling filters were supplied with H₂S at an input of lower than 1700 mg/m³, their removal efficiencies were nearly 98% regardless of previous H₂S input. Project supported by the Foundation for Society Development of Jilin Province (No. 20080412-1), the Education Research Foundation for Science and Technology Development of Jilin Province, and the Foundation for Doctor Research in Northeast Dianli University of Jilin Province (No. BSJXM-200710), China     

Organic nitrogen components in soils from southeast China

Objective:To investigate the amounts of extractable organic nitrogen(EON),and the relationships between EON and total extractable nitrogen(TEN),especially the amino acids(AAs) adsorbed by soils,and a series of other hydrolyzed soil nitrogen indices in typical land use soil types from southeast China.Under traditional agricultural planting conditions,the functions of EON,especially AAs in the rhizosphere and in bulk soil zones were also investigated.Methods:Pot experiments were conducted using plants of pakchoi(Brassica chinensis L.) and rice(Oryza sativa L.).In the rhizosphere and bulk soil zone studies,organic nitrogen components were extracted with either distilled water,0.5 mol/L K2SO4or acid hydrolysis.Results:K2SO4-EON constituted more than 30% of TEN pools.K2SO4-extractable AAs accounted for 25% of EON pools and nearly 10% of TEN pools in rhizosphere soils.Overall,both K2SO4-EON and extractable AAs contents had positive correlations with TEN pools.Conclusions:EON represented a major component of TEN pools in garden and paddy soils under traditional planting conditions.Although only a small proportion of the EON was present in the form of water-extractable and K2SO4-extractable AAs,the release of AAs from soil exchangeable sites might be an important source of organic nitrogen(N) for plant growth.Our findings suggest that the content of most organic forms of N was significantly greater in rhizosphere than in bulk soil zone samples.However,it was also apparent that the TEN pool content was lower in rhizosphere than in bulk soil samples without added N.     

Vapor-liquid equilibrium simulation of binary and ternary mixtures of CH4, C2H4 and iso-C4H10

The vapor-liquid equilibrium（VLE） properties for the binary and ternary mixtures of CH4,C2H4 and isoC4H10 are of great importance in the recovery of ethylene from mixture containing CH4 and C2H4 with iso-C4H10 as solvent.Hence,Gibbs ensemble Monte Carlo（GEMC） simulations were used to estimate vapor-liquid equilibrium for the binary and ternary mixtures of CH4,C2H4 and iso-C4H10 with the united atom potential NERD model.The selected simulation conditions are based on the experiment in the literature.The results of this work were shown to be in satisfactory agreement with available experimental data and predictions of Peng-Robinson equation of state.The structure of simulated liquid phase is also characterized by radial distribution function（RDF）,which contributes to further understanding of the VLE curve of these systems.RDF is not sensitive to the pressure and temperature range.With the increase of pressure or the decrease of temperature,the molecules tend to gather together.     

2000-2020年中国氮氧化物排放清单及排放趋势

研究目的：建立2000-2020年中国氮氧化物排放清单,了解中国主要行业和省份氮氧化物的排放情况,为评估氮氧化物的环境影响和制定相关减排政策提供依据。创新要点：分析了中国主要省份产业结构对氮氧化物排放量的影响;根据不同情景分析,预测2020年中国氮氧化物的排放量。研究方法：1．基于自底向上法,根据不同类型化石燃料的氮氧化物排放因子,结合化石燃料消耗量,建立中国2000-2010年氮氧化物排放清单;2．基于IPAT方程,并以中国2000--2010年的国内生产总值增长数据和氮氧化物排放量为依据,分三种情景,分析2011-2020年中国能源消耗和氮氧化物排放趋势。重要结论：2010年中国氮氧化物的排放量约是2000年的两倍：自2009年起,中国氮氧化物总排放量超过,二氧化硫总排放量;主要由于产业结构和地区生产总值的不同,中国东部和西部氮氧化物排放量有明显差异;制造业、电力行业和交通运输业是中国氮氧化物的主要排放源,其中交通运输业氮氧化物排放量呈现逐年增长趋势;预计2020年中国氮氧化物排放量为19．7Mt。     

Influence of annealing conditions on the properties of Cu(In,Ga)Se<Subscript>2</Subscript> thin films fabricated by electrodeposition

Cu(In,Ga)Se₂ (CIGS) precursor films were deposited on Mo/glass by electrodeposition, and then annealed in Se vapor. The annealing temperature ranged from 450 °C to 580 °C, and two heating rates were selected. The results showed that the crystalline quality of the CIGS films and formation of the Cu-Se compound could be strongly influenced by the selenization temperature and heating rate. Raman spectroscopy and X-ray diffraction (XRD) analysis showed that when the selenization temperature was increased from 450 °C to 550 °C, the amount of binary CuSe phase decreased and the amount of Cu2Se increased. After annealing at 580 °C, a minimum amount of Cu_2?xSe compounds was obtained and the degree of CIGS film crystallinity was higher than in other samples. The relationship between the properties of the film and the heating rate was studied. XRD and Raman spectra showed a decrease in the Cu_2?xSe phase with increasing heating rate. Scanning electron microscopy (SEM) and XRD showed a remarkable increase in the grain size of CIGS during rapid heating.     

Fabrication of Ce-ReS2 by Molten Salt for Electrochemical Hydrogen Evolution

Renewable and economical generation of hydrogen via electrochemical methods shows great potential in addressing the energy crisis. In this study, an emerging molten salt method was adopted for the synthesis of a cerium-modified rhenium disulfide nanosheet for electrical hydrogen evolution reactions. The prepared 1% Ce-doped rhenium disulfide (ReS₂) sample showed promoted hydrogen evolution performance in both acid and alkaline electrolytes compared to bare ReS₂. Generating of abundant defects in ReS₂ exposed more reaction active sites. Moreover, adding cerium accelerated the hydrogen evolution dynamics. Hopefully, this work will offer new insight into developing ReS₂-based electrocatalysts for hydrogen evolution reactions.

     

Chemical kinetic modeling for the effects of methyl ester moiety in biodiesel on PAHs and NO x formation

In order to investigate the effects of methyl ester moiety on polycyclic aromatic hydrocarbons (PAHs) and NO x formation in biodiesel combustion, the combined models were developed based on detailed methyl butanoate (MB) oxidation model and n-butane model. Also, PAHs detailed reaction mechanism and NO x formation mechanism were added to the detailed models to form the combined models. The combined models were used to compare the combustion of n-butane and MB in a shock tube simulation to understand the effects of methyl ester moiety. The results indicated that compared with n-butane, the methyl ester moiety in MB leads to different reaction pathways, more CO and CO 2 formation and less formation of PAHs precursors such as ethylene and acetylene. In addition, a better chemical insight into the effects of methyl ester moiety on NO x formation was given, which will help to understand the combustion process of biodiesel.     

Effect of rich air/fuel ratio and temperature on NO x desorption of lean NO x trap

An experimental and model-based study of the effect of rich air/fuel ratios （AFRs） and temperature on the NOx slip of a lean NOx trap （LNT） was conducted in a lean-burn gasoline engine with an LNT after-treatment system. The emissions of the engine test bench and the inlet temperature of the LNT were used as the major inlet boundary conditions of the LNT. The engine periodically operated between a constant lean AFR of 23 with alterable rich AFRs of 10, 11, 12, 13, and 14. A decrease in the rich AFR of the engine strengthened the desorption atmosphere in the LNT, an effect closely related to the number of reductants, and further heightened the NOx desorption of the LNT, but with a penalty in fuel consumption. To eliminate that penalty, the inlet boundary conditions of the LNT were varied by adjusting the inlet temperature within a range between 200 ℃ and 400℃. An increase in inlet temperature heightened the NOx desorption of the LNT, and a NOx breakthrough occurred after the inlet tem- perature exceeded 390 ℃. To control NOx breakthrough, the inlet temperature can be adjusted to offset the strong desorption atmosphere in the LNT commonly created by a rich AFR.     

Novel Method for Preparing a Carbon Nanotube-Supported Cobalt Catalyst for Fischer–Tropsch Synthesis:Hydrogen Dielectric-Barrier Discharge Plasma

Hydrogen dielectric-barrier discharge (H₂-DBD) plasma was successfully used to prepare carbon nanotubes (CNTs)-supported cobalt (Co) catalyst. The H₂-DBD plasma treatment simultaneously decomposed and reduced the cobalt precursor at a lower temperature and in a shorter time than the conventional method (calcination and hydrogen reduction). It is considered that the H₂-DBD plasma method can remarkably decrease the amount of energy input compared to traditional methods used to prepare the Co-based catalyst in Fischer–Tropsch synthesis (FTS). Results showed that the Co catalyst prepared by H₂-DBD plasma had an equivalent catalytic performance for FTS as that prepared using the conventional method in calcination and hydrogen reduction, thereby determining that H₂-DBD plasma was an effective alternative treatment for preparing the Co/CNTs catalyst for FTS. This technology will provide a new strategy for preparing catalysts in other catalysis processes.