Process design and economic analysis of methacrylic acid extraction for three organic solvents

In this work,a techno-economic study for the solvent based extraction of methacrylic acid from an aqueous solution is presented.The involved phase equilibrium calculations in process design are verified by measured experimental data.First,experiments are conducted with different solvent candidates to measure LLE(liquid–liquid equilibrium)data and to establish the effects of extraction temperature and dosage of solvent.Next,the binary interaction parameters for the UNIQUAC model to be used for equilibrium calculations are fine-tuned with measured data.Then,a process for the solvent based extraction of methacrylic acid recovery is designed and verified through simulation with the regressed UNIQUAC model parameters.The optimal configuration of the process flowsheet is determined by minimizing the total annualized cost.Among the three solvent candidates considered-cyclohexane,hexane and toluene-the highest efficiency and the lowest total annualized cost is found with toluene as the solvent.

Silver modified Cu/SiO2 catalyst for the hydrogenation of methyl acetate to ethanol

A series of silver modified Cu/SiO2 catalysts were synthesized with ammonia-evaporation method and applied in vapor-phase hydrogenation of methyl acetate to ethanol.The influence of additive‘Ag’on the structural evolution of catalyst was systematically studied by several characterization techniques,such as N2 adsorption–desorption,N2O titration,PXRD,FTIR,in-situ FTIR,H2-TPR,H2-TPD,XPS and TEM.Results showed that incorporation of a small amount of Ag could enhance the structural stability,and the strong interaction between Cu and Ag species was conducive to increase the dispersion of copper species and create a suitable Cu+/(Cu0+Cu+)ratio,which was proposed to be responsible for the improved catalytic activity.The maximum conversion of MA(94.1%)and selectivity of ethanol(91.3%)over optimized Cu-0.5 Ag/SiO2 and 120 h on stream without deactivation under optimal conditions demonstrates its excellent stability.

A perspective of chalcogenide semiconductor-noble metal nanocomposites through structural transformations

Intense efforts have been devoted to the synthesis of heterogeneous nanocomposites consisting of chalcogenide semiconductors and noble metals,which usually exhibit enhanced properties owing to the synergistic effect between their different material domains.Tailoring the structure of the metal domains in the nanocomposites may lead to further improvements of its performance for a given application.This review therefore highlights the strategies based on a structural conversion process for the fabrication of nanocomposites consisting of chalcogenide semiconductors and noble metals with various internal structures,e.g.,hollow or cage-bell.This strategy relies on a unique inside-out diffusion phenomenon of Ag in core-shell nanoparticles with Ag residing at core or inner shell region.In the presence of sulfur or selenium precursors,the diffused Ag are converted into Ag2S or Ag2Se,which is connected with the remaining noble metal parts,forming nanocomposites consisting of silver chalcogenide and noble metal nanoparticles with hollow or cage-bell structures.We would focus on the introduction of the fundamentals,principles,electrocatalytic applications as well as perspectives of the chalcogenide semiconductor-noble metal nanocomposites derived from their core-shell precursors so as to provide the readers insights in designing efficient nanocomposites for electrocatalysis.

High-performance Si-Containing anode materials in lithium-ion batteries: A superstructure of Si@Co-NC composite works effectively

To mitigate the massive volume expansion of Si-based anode during the charge/discharge cycles,we synthesized a superstructure of Si@Co±NC composite via the carbonization of zeolite imidazolate frameworks incorporated with Si nanoparticles.The Si@Co±NC is comprised of Sinanoparticle core and N-doped/Co-incorporated carbon shell,and there is void space between the core and the shell.When using as anode material for LIBs,Si@Co±NC displayed a super performance with a charge/discharge capacity of 191.6/191.4 mA h g^(-1)and a coulombic efficiency of 100.1%at 1000 mA g^(-1)after 3000 cycles,and the capacity loss rate is 0.022%per cycle only.The excellent electrochemical property of Si@Co±NC is because its electronic conductivity is enhanced by doping the carbon shell with N atoms and by incorporating with Co particles,and the pathway of lithium ions transmission is shortened by the hollow structure and abundant mesopores in the carbon shell.Also,the volume expansion of Si nanoparticles is well accommodated in the void space and suppressed by the carbon host matrix.This work shows that,through designing a superstructure for the anode materials,we can synergistically reduce the work function and introduce the confinement effect,thus significantly enhancing the anode materials’electrochemical performance in LIBs.

High recycling Fe_(3)O_(4)-CdTe nanocomposites for the detection of organophosphorothioate pesticide chlorpyrifos

To alleviate the secondary contamination of our environment when using quantum dots(QDs) to detect the organophosphorothioate pesticides(OPPs),we herein report a strategy to assemble magnetic Fe_(3)O_(4) nanoparticles and luminescent Cd Te quantum dots(QDs) into a composite nanosystem,which possesses both the magnetic property of Fe_(3)O_(4) nanoparticles and the luminescent character of Cd Te QDs,for the detection of chlorpyrifos,one of the typical OPPs.This strategy involves the isolated synthesis of magnetic Fe_(3)O_(4) nanoparticles with positive charges and luminescent Cd Te QDs with negative charges,and their subsequent assembly by electrostatic interaction.The as-prepared Fe_(3)O_(4)-Cd Te nanocomposites have a detection limit as low as 10 ppb for chlorpyrifos,and are also selective for the OPPs with a phosphorothioate moiety(P=S bond).In specific,the Fe_(3)O_(4)-Cd Te nanocomposites can be conveniently harvested by a normal magnet,and the recycling rate for both Cd and Fe determined by inductively coupled plasma atomic emission spectroscopy(ICP-AES) is higher than 96%,showing great potential in alleviating the Cd pollution on the environment.

Cooperative catalytic effects between the penta-coordinated Al and Al_(2)O_(3)in Al_(2)O_(3)-AlPO_(4)for aldol condensation of methyl acetate with formaldehyde to methyl acrylate

The bare amorphous Al_(2)O_(3)-AlPO_(4)and Cs/Al_(2)O_(3)-AlPO_(4)catalysts were developed for the aldol condensation of methyl acetate with formaldehyde to methyl acrylate.The structure and property of catalyst were characterized by XRD,XPS,BET,Pyridine-IR,FT-IR,^(27)Al-MASNMR,NH_(3)-/CO_(2)-TPD and SEM.The correlation between structural features and acid-base properties was established,and the loading effect of the cesium species was investigated.Due to cooperative catalytic effects between the penta-coordinated Al and Al_(2)O_(3),the weak-Ⅱacid and medium acid site densities and the product selectivity were improved.While the basic site densities of these catalysts were almost in proportion to the conversion of methyl acetate.The loaded Cs could form new basic sites and change the distribution of acid sites which further enhance the catalytic performance.As a result,the 10Cs/8AlP was proved to be an optimal catalyst with the yield and selectivity of 21.2%and 85%for methyl acrylate respectively.During the reaction,a deactivation behavior was observed on 10Cs/8AlP catalyst due to the carbon deposition,however,it could be regenerated by thermal treatment in the air atmosphere at 400℃.

Rough-surfaced bimetallic copper–palladium alloy multicubes as highly bifunctional electrocatalysts for formic acid oxidation and oxygen reduction

Engineering the morphology of nanomaterials and modifying their electronic structure are effective ways to improve their performance in electrocatalysis. Through combining the co-reduction of Pd2+ and Cu2+ precursors with a digestive ripening process in oleylamine, we report the synthesis of copper-palladium(Cu-Pd) alloy multicubes with rough surfaces. Benefiting from their alloy and unique rough-surfaced structure,which provides ample edge/corner and step atoms as well as the electronic coupling between Cu and Pd leading to the lower of d-band center, the rough-surfaced Cu-Pd alloy multicubes show much better electrocatalytic performance not only for formic acid oxidation but also for oxygen reduction in comparison with those of spherical Cu-Pd alloy nanoparticles and commercial Pd/C catalyst. In contrast, we confirm that the rough-surfaced Cu-Pd alloy multicubes only exhibit very low Faradaic efficiency(34.3%) for electrocatalytic conversion of carbon dioxide(CO2) to carbon monoxide(CO) due to the presence of strong competing hydrogen evolution reaction, which results in their very poor selectivity for the reduction of CO2 to CO. The findings in this study not only offer a promising strategy to produce highly effective electrocatalysts for direct formic acid fuel cells, but also enlighten the ideas to design efficient electrocatalysts for CO2 reduction.

Advanced Nonflammable Localized High-Concentration Electrolyte For High Energy Density Lithium Battery

The key to realize long-life high energy density lithium batteries is to exploit functional electrolytes capable of stabilizing both high voltage cathode and lithium anode.The emergence of localized high-concentration electrolytes(LHCEs)shows great promise for ameliorating the above-mentioned interfacial issues.In this work,a lithium difluoro(oxalate)borate(LiDFOB)based nonflammable dual-anion LHCE is designed and prepared.Dissolving in the mixture of trimethyl phosphate(TMP)/1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropylether(D_(2)),the continuously consumption of LiDFOB is suppressed by simply introducing lithium nitrate(LiNO_(3)).Meantime,as most of the TMP molecular are coordinated with Li^(+),the electrolyte does not show incompatibility issue between neither metal lithium nor graphite anode.Therefore,it demonstrates excellent capability in stabilizing the interface of Ni-rich cathode and regulating lithium deposition morphology.The Li||LiNi_(0.87)Co_(0.08)Mn_(0.05)O_(2)(NCM87)batteries exhibit high capacity retention of more than 90%after 200 cycles even under the high cutoff voltage of 4.5 V,1 C rate.This study offers a prospective method to develop safe electrolytes suitable for high voltage applications,thus providing higher energy densities.

Ordered mesoporous Cu-Ca-Zr:A superior catalyst for direct synthesis of methyl formate from syngas

It is still a big challenge to obtain both highly active and stable Cu-based catalysts for direct synthesis of methyl formate(MF)from syngas.To address the issue,we have designed and synthesized a series of ternary Cu-Ca-Zr catalysts,namely,the ordered mesoporous Cu-Ca-Zr catalyst prepared by one-pot evaporation-induced self-assembly(EISA)method,and the supported CuO/CaO-ZrO_(2)catalysts by impregnating with copper precursor or by immobilizing copper nanoparticles.In the latter two catalysts,the ordered mesoporous CaO-ZrO_(2)support was also prepared by the EISA method.The catalysts were characterized by techniques such as ICP,XRD,TEM,N2 isotherm adsorption-desorption,XPS and H2-TPR,and used for direct synthesis of MF.The results indicated that the catalyst prepared by onepot EISA method,in which the CuO species are highly dispersed in frame of CaO-ZrO_(2),exhibits much better activity and stability as compared with the other two catalysts with most of CuO located on the outer surface of the CaO-ZrO_(2)support,because the former has a higher specific surface area,enhanced synergistic effect and stronger interaction between the CaO-ZrO_(2)support and CuO active constituent.

Ionic-microenvironment stabilizes the disulfide engineered lysine decarboxylase for efficient cadaverine production

Cadaverine is the key monomer for the synthesis of nylon 5X.Efficient and alkaline stable lysine decarboxylases are highly desirable for cadaverine production as the reaction pH increasing from 6.3 to 8.5.However,the most studied lysine decarboxylase CadA(E.coli)lost almost all activity at pH 8.0,which is the foremost challenge for the industrial-cadaverine production.In this study,we first found that the Na^(+)-microenvironment significantly improved the alkaline stability of the disulfide engineered lysine decarboxylaseΔLdcEt3(P233C/L628C)(half-life 362 h),compared to the conventional buffer(half-life 0.66 h)at pH 8.0.Meanwhile,the whole-cell conversion efficiency of the industrial-grade L-lysine withΔLdcEt3 could reach up to 99%in 2 h in the fermenter.Experi-mental investigation and molecular dynamics confirmed that Na^(+)-microenvironment could improve active-aggregation state and affect secondary structure ofΔLdcEt3.Therefore,Na^(+)-microenvironment stabilizesΔLdcEt3 providing a great potential industrial application for high-level cadaverine production.