FeNiO_x和LiOH催化剂体系上乙醇转化到丁醇（英文）

随着生物发酵技术的进步和化学转化方法的发展,全球乙醇产量迅速增加.然而,乙醇存在能量密度低、吸水、对发动机腐蚀性高等缺点,其在汽油中的添加量有限,一般低于15%,这严重限制了乙醇产业的发展.与此相比,丁醇具有更高的能量密度和汽油添加量,是一种更加理想的油品添加剂.因此,乙醇催化转化为丁醇是连接高乙醇产量和优质丁醇需求的桥梁,具有重要的学术和应用价值.在过去的几十年里,均相催化剂、复合氧化物催化剂、羟基磷灰石及金属促进的氧化物催化剂迅速发展,但是仍存在乙醇转化率低、丁醇选择性差和催化剂不能循环等问题.乙醇催化转化为丁醇是一个Guerbet反应,乙醇首先脱氢生成乙醛,乙醛通过缩合、脱水生成巴豆醛,巴豆醛通过加氢得到丁醇.反应中主要涉及氢转移活性位和羟醛缩合活性位.因此,本文中我们根据催化反应机理,筛选了不同金属氧化物和碱催化剂体系,分别用于乙醇脱氢、巴豆醛加氢和乙醛缩合、脱水反应.结果发现,在FeNiOx和LiOH催化体系中,乙醇转化率和丁醇选择性最好.通过优化反应温度、反应时间、金属氧化物和碱量等条件,在493 K反应釜中反应24 h,得到28%的乙醇转化率、71%的丁醇选择性和超过90%的C4-C8高碳醇选择性,达到了部分均相贵金属催化剂上的反应结果.在FeNiOx和LiOH催化体系中,FeNiOx具有较强的磁性,便于磁性分离,循环八次后仍具有较高的催化活性,展示出优异的稳定性.LiOH可以通过蒸馏分离,循环三次没有明显失活,但有少量Li2CO3生成,其可以通过焙烧的方式恢复.通过穆斯堡尔谱、氢气吸附、XPS等表征和条件实验发现,FeNiOx中存在金属态的镍、铁和不同氧化态的铁物种,其能促进乙醇的脱氢和后续巴豆醛的加氢,起到氢转移的作用.LiOH具有合适的酸碱性,能够促进乙醛的羟醛缩合,并加速乙醇转化.在两者协同作用下,乙醇转化率和丁醇选择性都有显著提高.这一研究策略对此反应中新型催化剂的开发和反应机理的认识都具有重要的推动作用.

Dynamic failure risk of coal pillar formed by irregular shape longwall face:A case study

Irregular shape workface would result in the presence of coal pillar, which leads to high stress concentration and possibly induces coal bumps. In order to study the coal bump mechanism of pillars, static and dynamic stress overlapping(SDSO) method was proposed to explain the impacts of static stress concentration and tremors induced by mining activities. The stress and deformation in surrounding rock of mining face were analyzed based on the field case study at 1303 workface in Zhaolou Coal Mine in China.The results illustrate that the surrounding rock of a workface could be divided into four different zones,i.e., residual stress zone, stress decrease zone, stress increase zone and original stress zone. The stress increase zone is prone to failure under the SDSO impact loading conditions and will provide elastic energy for inducing coal bump. Based on the numerical modelling results, the evolution of static stress in coal pillar as the size of gob increasing was studied, and the impact of dynamic stress was investigated through analyzing the characteristics of tremor activities. The numerical results demonstrate the peak value of vertical stress in coal pillar rises from about 30 MPa with mining distance 10 m to 52.6 MPa with mining distance 120 m, and the location of peak stress transfers to the inner zone of coal pillars as the workface moves forward. For the daily tremor activities, tremors with high energy released indicate high dynamic stress disturbance on the surrounding rock, therefore, the impact of dynamic stressing is more serious during workface extension period because the tremor frequency and average energy after workface extension are higher than those before the workface extension.

Water sorption on coal:effects of oxygen-containing function groups and pore structure

Coal-water interactions have profound influences on gas extraction from coal and coal utilization.Experimental measurements on three coals using X-ray photoelectron spectroscopy(XPS),low-temperature nitrogen adsorption and dynamic water vapor sorption(DVS)were conducted.A mechanism-based isotherm model was proposed to estimate the water vapor uptake at various relative humidities,which is well validated with the DVS data.The validated isotherm model of sorption was further used to derive the isosteric heat of water vapor sorption.The specific surface area of coal pores is not the determining parameter that controls water vapor sorption at least during the primary adsorption stage.Oxidation degree dominates the primary adsorption,and which togethering with the cumulative pore volume determine the secondary adsorption.Higher temperature has limited effects on primary adsorption process.The isosteric heat of water adsorption decreases as water vapor uptake increases,which is found to be close to the latent heat of bulk water condensation at higher relative humidity.The results confirmed that the primary adsorption is controlled by the stronger bonding energy while the interaction energy between water molecules during secondary adsorption stage is relatively weak.However,the thermodynamics of coal-water interactions are complicated since the internal bonding interactions within the coal are disrupted at the same time as new bonding interactions take place within water molecules.Coal has a shrinkage/swelling colloidal structure with moisture loss/gain and it may exhibit collapse behavior with some collapses irreversible as a function of relative humidity,which further plays a significant role in determining moisture retention.

Active and stable Cu doped NiMgAlO catalysts for upgrading ethanol to n-butanol

Upgrading ethanol to n-butanol is an attractive way for renewable n-butanol production. Herein, Cu was selected to modify NiMgAlO catalysts for improving ethanol conversion and n-butanol selectivity. Over the optimized 2%Cu-NiMgAlO catalyst, ethanol conversion and n-butanol selectivity were enhanced to 30.0% and 64.2%, respectively, in 200 h time on stream at 523 K. According to physicochemical characterizations and theoretical calculations, the key role of multiple active sites in this reaction was extensively investigated. The plate-like structure of hydrotalcite was maintained over 2%Cu-NiMgAlO catalysts, with an average Ni particle size of ca. 5.4 nm. The presence of Cu species created CuNi alloy sites and Lewis acid-base pairs, and increased hydrogen transfer and condensation reactions, resulting in elevated ethanol conversion and n-butanol selectivity. Additionally, CuNi alloy had a strong interaction with CuNiMgAl oxides, forming homogeneous boundary due to their close ionic radius and lattice matching, and afforded the long time stability in the ethanol to n-butanol reaction.

Experimental study on the adverse effect of gel fracturing fluid on gas sorption behavior for Illinois coal

Hydraulic fracturing is an effective technology for coal reservoir stimulation.After fracturing operation and flowback,a fraction of fracturing fluid will be essentially remained in the formation which ultimately damages the flowability of the formation.In this study,we quantified the gel-based fracturing fluid induced damages on gas sorption for Illinois coal in US.We conducted the high-pressure methane and CO_(2)sorption experiments to investigate the sorption damage due to the gel residue.The infrared spectroscopy tests were used to analyze the evolution of the functional group of the coal during fracturing fluid treatment.The results show that there is no significant chemical reaction between the fracturing fluid and coal,and the damage of sorption is attributed to the physical blockage and interactions.As the concentration of fracturing fluid increases,the density of residues on the coal surface increases and the adhesion film becomes progressively denser.The adhesion film on coal can apparently reduce the number of adsorption sites for gas and lead to a decrease of gas sorption capacity.In addition,the gel residue can decrease the interconnectivity of pore structure of coal which can also limit the sorption capacity by isolating the gas from the potential sorption sites.For the low concentration of fracturing fluid,the Langmuir volume was reduced to less than one-half of that of raw coal.After the fracturing fluid invades,the desorption hysteresis of methane and CO_(2)in coal was found to be amplified.The impact on the methane desorption hysteresis is significantly higher than CO_(2)does.The reason for the increasing of hysteresis may be that the adsorption swelling caused by the residue adhered on the pore edge,or the pore blockage caused by the residue invasion under high gas pressure.The results of this study quantitatively confirm the fracturing fluid induced gas sorption damage on coal and provide a baseline assessment for coal fracturing fluid formulation and technology.

Respirable nano-particulate generations and their pathogenesis in mining workplaces:a review

There is a growing concern in mining community about the contribution of nano-particulates to miner's health.Despite the health influence of respirable dusts and associated lung diseases have been recognized for decades in the mining industry,the nano-scale particulates accompanying with complicated physiochemical properties and their enor-mous contribution in quantity have been drawing attentions only in recent a few years because of the advancement of nano-science discipline.In this review,we examine the current regulations of dusts exposure and the dominant mass-based monitoring methods to point out the ignorance of nano-particulates in mining industry.The recognized mining-related nano-particulates sources are summarized to identify the mechanically generated finer particulates including particles and aerosols.In addition,the mechanism of adverse health impact on miner with exposure to nano-scale particulates is discussed in a detail to emphasize their substantial detriment as a potential respiratory hazard.Characterization of the complex physiochemical properties of nano-particulates are then summarized and discussed because these properties could be different from regular respirable dusts due to their dramatically increased surface area and particulate counts.The intent of this review is to demonstrate the potential of adverse health effect of nano-particulate on the mine personals throughout the mining cycle and to identify the research gaps of the mine nano-particulate characterization and quantification.We suggest that further understanding of the mining induced nano-particulate properties and their pathogenesis are critical for the future engineering control measure to mitigate the potential health threat for future miners.

Special Issue on mine dust research:health effects and control technologies

Coal remains one of the principal sources of energy for the world.During the extraction,transport,and processing of coal in underground and surface mining operations,sig-nificant amounts of airborne respirable dusts can be gen-erated and released to the working space.Chronic exposure to coal dusts puts the miners at risk for various lung dis-eases,including coal workers'pneumoconiosis,emphy-sema,silicosis,and chronic bronchitis.Apart from the miners'lung disease,the coal mine dusts also potentially increase the risk of mine explosion which has been rec-ognized as one of the most severe hazards in underground coal mine.

Anti-angiogenic effect of tripterygium glycosides tablets in animal models of rheumatoid arthritis:A systematic review and meta-analysis

Objectives:To explore and summarize the beneficial effects of a traditional Chinese medicine preparation,Tripterygium glycosides tablets(TGT),in rheumatoid arthritis(RA)animal models of neovascularization,and to provide a reference for future clinical applications and research on its pharmacologic mechanism.Methods:We searched the databases PubMed,Embase,Web of Science,Chinese National Knowledge Infrastructure,VIP,Wan Fang and SinoMed(China Biomedical Document Service System)to identify studies of TGT with outcome indicators of angiogenesis-related factors that were published before April2020.Subgroup analysis and meta-regression were performed for dosage and duration of TGT.Statistical tests and subgroup analysis were conducted using RevMan 5.3,and meta-regression and sensitivity analysis were conducted using STATA/SE 15.0.Results:Fourteen studies of TGT in RA rats were included in this analysis.Treatment with TGT significantly reduces synovial microvessel density and the expression of vascular endothelial growth factor(VEGF),VEGF receptor 2,hypoxia inducible factor a,c-Fos,c-Jun,angiopoietin-1 and angiopoietin-2 compared with control groups(P<.05).Subgroup analysis did not show a significant association of the mRNA levels of VEGF in synovium,assessed using quantitative real-time PCR,with duration or dosage of TGT.Meta-regression analysis also indicated that the effects of dosage and duration were not significantly associated with differences in VEGF mRNA levels.Sensitivity analysis on VEGF m RNA levels did not fundamentally change the results.Conclusions:TGT can reduce synovial neovascularization by decreasing synovial microvessel density and expression of VEGF,VEGF receptor 2,hypoxia-inducible factor a,c-Fos,c-Jun,Ang-1 and Ang-2,thereby suppressing pannus formation and bone destruction in rat models of RA.Additional well-designed studies are required to confirm these findings.

Influences of various grazing systems on community biomass of a desert grassland in Inner Mongolia,China

This study investigated the effects of various grazing systems, including continuous grazing, rotational grazing, and no-grazing systems, on the community biomass in the Stipa breviflora Griseb desert grassland during the grazing seasons in 2005, 2006, and 2007, based on study sites established in 1999. We found that the seasonal dynamics of the aboveground biomass were quite similar among the three treatments, which reached peak values in period from August to September during each study year. The continuous grazing system reduced the aboveground biomass from 2005 to 2007 under drought conditions, and the rotational grazing and no-grazing systems maintained more aboveground biomass than the continuous grazing system did. The belowground biomass declined with the increase of soil depth among the three treatments, and in the surface 20-cm soil layer it accounted for more than 60% of the total biomass. The belowground biomass was found to be highly correlated with soil depth under rotational grazing. The total belowground biomass within the 0--100-cm soil layer for rotational grazing was sig- nificantly higher than for continuous grazing and no-grazing, and had 15,775 kg/ha more biomass. Our results demonstrate that conservative rotational grazing can alleviate grassland deterioration by reserving more aboveground and belowground biomass than the continuous grazing system does.

非光气制异氰酸酯绿色过程

异氰酸酯是聚氨酯合成的主要原料.目前,工业上主要采用光气法制备异氰酸酯.该工艺使用剧毒的光气同时副产大量腐蚀性的氯化氢.非光气制异氰酸酯是绿色化学及相关过程的最重要的内容,它的实现将导致传统的光气工艺乃至聚氨酯行业产生革命性的变化.本文主要介绍了本课题组多年来不同羰源下催化羰化制N-取代氨基甲酸烷基酯、热裂解制备异氰酸两步反应的研究进展及存在的问题,特别是近两年本课题组在脂肪族N-取代氨基甲酸烷基酯热裂解过程中聚合物的形成与解聚方面的思路,提出了具有工业实际应用价值的非光气制异氰酸酯的三步反应过程.

Important Green Chemistry and Catalysis： Non-phosgene Syntheses of Isocyanates - Thermal Cracking Way

Currently, industrial production of isocyanates, or diisocyanates in particular, has been exclusively based on phosgene processes. Phosgene is extremely toxic and large amounts of corrosive HC1 are produced as a side product. In the view of environment protection and society safety, development of non-phosgene processes for isocyanates production will be highly desired, and this should be one of the most important missions for green chemistry and catalysis. In this review, efforts for development of non-phosgene method for syntheses of isocyanates, i.e., catalytic syntheses of N-substituted carbamates from nitro- or amino-compounds with CO, dimethyl carbonate （DMC）, urea and even CO2 etc. as carbonyl sources, then thermal cracking of N-substituted carbamates to afford corresponding i socyanates, are summarized, and a brief prospect for non-phosgene syntheses of isocyanates is also addressed.

Nano CuO/ZSM-5 zeolite as a green and efficient catalyst for dehydration of 1,4-butanediol to tetrahydrofuran

Nano CuO/ZSM-5 zeolite was prepared and used as a catalyst for dehydration of 1,4-butanediol(BDO) to tetrahydrofuran(THF) in liquid-phase. It was found that the 4.6 wt% CuO/ZSM-5 displayed good catalytic performance, and nearly 100%of BDO conversion and more than 99% of THF selectivity could be achieved by a rotary evaporator reactor at 170 °C under the atmospheric pressure. With such mild reaction conditions, 2400 g BDO could be converted to THF over 1 g catalyst under semi-continuous operation. Characterizations with X-ray diffraction(XRD), temperature-programmed reduction(TPR),NH3-temperature programmed desorption(TPD), X-ray photoelectron spectroscopy(XPS), transmission electron microscope(TEM) and Brunauer-Emmett-Teller(BET) over fresh and used 4.6 wt% CuO/ZSM-5 were conducted. Based on the results of the characterization and catalytic performance of 4.6 wt% CuO/ZSM-5, it can be conjectured that the formed 1–3 nm CuO nanoparticles, suitable acidity of the catalyst due to the synergic interaction of CuO and ZSM-5 support promoted the dehydration of BDO to THF.

Paternal transgenerational nutritional epigenetic effect:A new insight into nutritional manipulation to reduce the use of antibiotics in animal feeding

The use of antibiotics in animal feeding has been banned in many countries because of increasing concerns about the development of bacterial resistance to antibiotics and potential issues on food safety.Searching for antibiotic substitutes is essential.Applying transgenerational epigenetic technology to animal production could be an alternative.Some environmental changes can be transferred to memorylike responses in the offspring through epigenetic mechanisms without changing the DNA sequence.In this paper,we reviewed those nutrients and non-nutritional additives that have transgenerational epigenetic effects,including some amino acids,vitamins,and polysaccharides.The paternal transgenerational nutritional epigenetic regulation was particularly focused on mechanism of the substantial contribution of male stud animals to the animal industries.We illustrated the effects of paternal transgenerational epigenetics on the metabolism and immunity in farming animals and proposed strategies to modulate male breeding livestock or poultry.