Chemical Reaction Route Selection Based on Green Chemical Engineering

In the preliminary stage of chemical process design, the choice of chemical reaction route is the key design decision, and the concepts of atom utilization and environmental quotient have become extremely useful tools. However, the waste quality such as chemical toxicity and other engineering factors have not been taken into account. Therefore, a synthetic route selection index, Iroute, is proposed to determine the suitability of a chemical route in this paper. Iroute considers the effects of 'extended atom economy', material renewability, chemical characteristics and some engineering factors. The extended atom economy concept regards not only the value of the desired product but also the value of byproducts. The methodology by using Iroute to compare different routes is illustrated in case study of cyclohexanone oxime and acrylonitrile manufacture.

Homopteran Vector Biomarkers for Efficient Circulative Plant Virus Transmission are Conserved in Multiple Aphid Species and the Whitefly Bemisia tabaci

Plant viruses in the families Luteoviridae and Geminiviridae are phloem restricted and are transmitted in a persistent,circulative manner by homopteran insects.Using fluorescence 2-D difference gel electrophoresis to compare the proteomes of F2 genotypes of Schizaphis graminum segregating for virus transmission ability,we recently discovered a panel of protein biomarkers that predict vector competency.Here we used aphid and whitefly nucleotide and expressed sequence tag database mining to test whether these biomarkers are conserved in other homopteran insects.S.graminum gene homologs that shared a high degree of predicted amino acid identity were discovered in two other aphid species and in the whitefly Bemisia tabaci.Selected reaction monitoring mass spectrometry was used to validate the expression of these biomarkers proteins in multiple aphid vector species.The conservation of these proteins in multiple insect taxa that transmit plant viruses along the circulative transmission pathway creates the opportunity to use these biomarkers to rapidly identify insect populations that are the most efficient vectors and allow them to be targeted for control prior to the spread of virus within a crop.

Importance, features and uses of metal oxide catalysts in heterogeneous catalysis

This short review paper aims at assembling the present state of the art of the multiuses of metal oxides in heterogeneous catalysis, concerning liquid and gaseous phases of the reactant mixtures on solid catalysts. It includes the description of the main types of metal oxide catalysts, of their various preparation procedures and of the main reactions catalysed by them (acid-base type, selective and total oxidations, bi-functional catalysis, photocatalysis, biomass treatments, environmental catalysis and some of the numerous industrial applications). Challenges and prospectives are also discussed.

Effect of CeO_(2) nanoparticle sizes on catalytic performances of sulfated CeO_(2)/Al_(2)O_(3) catalyst in NH_(3)-SCR reaction

The sulfated CeO_(2)/Al_(2)O_(3) catalysts with different sizes of CeO_(2)nanoparticles were prepared by using pure H_2O or acetic acid solution as impregnation solvent, and the influence of sizes of CeO_(2) nanoparticles on the catalytic performances of the sulfated CeO_(2)/Al_(2)O_(3) catalyst was studied. The catalytic performance tests show that the sulfated CeO_(2)/Al_(2)O_(3) catalyst using acetic acid solution as impregnation solvent has better catalytic activity and the resistance to K+poisoning than the sulfated CeO_(2)/Al_(2)O_(3) catalyst using pure H_(2)O as impregnation solvent. The excellent catalytic performances can be ascribed to the smaller sizes of CeO_(2) nanoparticles in CeO_(2)/Al_(2)O_(3) catalyst using acetic acid solution, which results in larger amount of adsorbed sulfate species, surface acid sites, surface active oxygen species and excellent redox property. These features are helpful for improving the catalytic performances of sulfated CeO_(2)/Al_(2)O_(3) catalyst using smaller amount of CeO_(2) to cut the costs.

2D phosphides heterostructures on titanium microfiltration membrane for enhanced ampere-level current density overall seawater splitting

The advancement of direct seawater electrolysis is a significant step towards sustainable hydrogen production,addressing the critical need for renewable energy sources and efficient resource utilization.However,direct seawater electrolysis has to face several challenges posed by the corrosiveness of highly concentrated chloride and the competitive chlorine evolution reaction(ClER).To overcome these issues,we designed a novel NiP_(2)@CoP electrocatalyst on a porous titanium microfiltration(Ti MF)membrane.The obtained bifunctional NiP_(2)@CoP catalyst outperforms the Pt/C and IrO_(2),as evidenced by its low overpotentials of 192 and 425 mV at a current density of 500 mA·cm^(-2) for hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)in alkaline seawater(1 M KOH+0.5 M NaCl),respectively.Especially,only 231 and 569 mV overpotentials are required at the current density of 1500 mA·cm^(-2) towards HER and OER in alkaline seawater,respectively.More importantly,no ClER was observed,demonstrating its excellent selectivity to OER.The selection of porous Ti MF membrane as an electrode substrate further enhances the performance by providing a robust structure that promotes the fast generation and release of gas bubbles.Our promising outcomes obtained with NiP_(2)@CoP catalysts on Ti MF support,therefore,pave the way for the commercial viability of direct seawater electrolysis technologies at industrial-level current densities.

Surface modification boosts exciton extraction in confined layered structure for selective oxidation reaction

Extracting photogenerated species from bulk to surface is an essential process for gaining efficient semiconductor-based photocatalysis.However,compared with charged photogenerated carriers,neutral exciton exhibits negligible response to electric field.Accordingly,traditional strategies involving band-alignment construction for boosting directional transfer of charge carriers are impracticable for extracting bulk excitons.To this issue,we here propose that the extraction of bulk exciton could be effectively implemented by surface modification.By taking confined layered bismuth oxycarbonate(Bi_(2)O_(2)CO_(3))as an example,we highlight that the incorporation of iodine atoms on the surface could modify the micro-region electronic structure and hence lead to reduced energy of surface excitonic states.Benefiting from the energy gradient between bulk and surface excitonic states,iodine-modified Bi_(2)O_(2)CO_(3)possesses high-efficiency bulk exciton extraction,and hence exhibits promoted performance in triggering1 O2-mediated selective oxidation reaction.This work presents the positive role of surface modification in regulating excitonic processes of semiconductor-based photocatalysts.

Chemo-selective Suzuki–Miyaura reactions:Synthesis of highly substituted[1,6]-naphthyridines

The Suzuki-Miyaura reaction of methyl-5-bromo-8-（tosyloxy）-1,6-naphthyridine-7-carboxylate（5）,with 2 equiv. of arylboronic acids gave diarylated product, 5,8–diaryl-1,6-naphthyridine-7-carboxylate（7）, whereas 1 equiv. of arylboronic acid resulted in site-selective formation of 5-aryl-8-（tosyloxy）-1,6-naphthyridine-7-carboxylate（8）. The reactions proceeded with excellent chemo-selectivity in favor of the bromide group. Likewise, one-pot reaction with completely different boronic acids by sequential addition produced 1,6-naphthyridine-7-carboxylates,（10） containing two different aryl groups at 5 and 8 positions.

The reactivities of Mo cluster——A selective substitution reaction of the bridging(dtp)ligand and the crystal structure of{Mo_3S_4(μ-O_2CR)(dtp)_3(Py)}

The reaction of trinuclear molybdenum cluster{Mo_3S_4(μ-dtp)(dtp)_3(H_2O)}1[dtp= S_2P(OEt)_2]with RCO_2Na(R=H,CH_3)in the presence of Py gave the black compounds{Mo_3S_4(μ- O_2CR)(dtp)_3(Py)}(2,R=H,3,R=CH_3).Both compounds are characterized by X-ray crystallo- graphy.It is shown that crystals 2 and 3 belong to space group P with Z=2 and a=10.519(2),b= 12.121(2),c=15.757(2),α=93.27(1),β=94.63(1),γ=105.22(1)°,V=1925~3 for crystal 2,whereas a=9.556(2),b=14.067(7),c=15.914(9),α=101.41(4),β=101.44(4),γ=74.26(3)°,V=1994~3 for crystal 3.The final R factors are 0.041 and 0.048 for crystal 2 and 3 respectively.The structure analysis indicates that(O_2CR)^- ligand selectively substitutes the bridging(dtp)ligand.This type of Mo_3 cluster molecule where structure contains two species of bidentate ligand is for the first time to be obtained by us.

Quantitative detection of single amino acid polymorphisms by targeted proteomics

Single-nucleotide polymorphisms(SNPs)are recognized as one kind of major genetic variants in population scale.However,polymorphisms at the proteome level in population scale remain elusive.In the present study,we named amino acid variances derived from SNPs within coding regions as single amino acid polymorphisms(SAPs)at the proteome level,and developed a pipeline of nontargeted and targeted proteomics to identify and quantify SAP peptides in human plasma.The absolute concentrations of three selected SAP-peptide pairs among 290 Asian individuals were measured by selected reaction monitoring(SRM)approach,and their associations with both obesity and diabetes were further analyzed.This work revealed that heterozygotes and homozygotes with various SAPs in a population could have different associations with particular traits.In addition,the SRM approach allows us for the first time to separately measure the absolute concentration of each SAP peptide in the heterozygotes,which also shows different associations with particular traits.

Erosion of a Polyimide Material Exposed to Simulated Atomic Oxygen Environment

Oxygen plasma source generated by thermal cathode filament discharge has been used to study the erosion process of polyim- ide （PI） materials in atomic oxygen （AO） environment, and their mass loss, surface morphology and surface chemical composi- tions have been examined by scanning electron microscope （SEM） and X-ray photoelectron spectroscopy （XPS） after exposure to incremental AO flux. The data indicate that the physical adsorption of AO at the samples＇ surface results in the increase of oxygen concentration when polyimide is exposed to AO flux. Then selective chemical reactions of groups of polyimide materials with AO yield volatile organic compounds, sample mass loss is on linear increase and carpet-like surface morphology forms. In the initial exposure to AO, the reaction occurs mainly between AO and carbon in specific location of aromatic ring, then the re- action rate of C=O groups gradually increases. After AO exposure, the oxygen concentration increases while nitrogen and carbon concentration decreases. Reaction rate of groups containing nitrogen is slower compared with carbon and oxygen.

Selective introduction of surface defects in anatase TiO2 nanosheets for highly efficient photocatalytic hydrogen generation

Defect engineering greatly enhances the cat-alytic activity of transition metal semiconductor photocat-alysts.Recently,localized surface defects engineering has been intensively researched,but it still remains challenges on how to tilt the balance to the controllable construction of surface defects rather than bulk ones.Here,we report a facile room-temperature solution processing strategy on(001)facet exposed anatase TiO_(2) nanosheets(ATO),in which localized defects are generated on the surface selectivity with high concentration.To achieve the aspect,lithium-ethylenediamine(Li-EDA)treatment is carried out on(001)facet exposed ATO under a mild condition.The optimized sample exhibits outstanding photocatalytic H_(2) production rates of 9.28 mmol·g^(-1)·h^(-1) with loading 0.5 wt%Pt as co-catalyst(AM 1.5),which is nearly 7.5 times higher than that of the pristine ATO.This defect engi-neering strategy of ATO photocatalyst will spark the ideas for the defects engineering and semiconductor photocata-lyst,which is with important application prospect in solar energy conversion,including hydrogen generation and carbon dioxide reduction.

Recent Progresses in Titanosilicates

Titanosilicates, with tetrahedrally coordinated Ti4＋ ions in highly crystalline zeolite frameworks, are a class of unique heterogeneous catalysts useful for the liquid-phase selective oxidation reactions. The great success of green Ti-zeolites/H2O2 reaction system has aroused considerable scientific and industrial interests. The catalytic properties of titanosilicates relay on zeolite topologies, crystal morphology, the content and micro-environment of tetrahedral Ti4＋ ions. The ever-growing needs for the oxidation catalysts in processing bulky molecules in petrochemical and fine chemical industries have set off a new tide of developing novel titanosilicates with significantly improved cat- alytic performance than traditional ones. This mini review summarizes recent progresses in developing the titano- silicates with novel topology, morphology as well as chemically modified micro-environment.

Effect of Copper Content on the Direct Process of Organosilane Synthesis from Silicon and Methyl Chloride

The effect of copper concentration on the performance of the catalytic reaction between silicon and methyl chloride was investigated using online gas chromatogram. The catalyst concentration greatly influences various aspects of the direct organosilane synthesis process, including the reaction rate, the selec- tivity, and the silicon conversion. The reaction activity and the silicon conversion increase as the catalyst concentration increases. However, the reaction selectivity decreases for the catalyst concentrations more .than 9 wt.%. The cross-sections of deactivated contact mass particles were observed by optical microscopy and analyzed by scanning electron microscope combined with energy dispersive X-ray detector （SEM-EDX） The observations showed that a textured substance formed on the original flat surface of the silicon particles after deactivation with copper only in a shallow surface layer of the contact mass. This indicates that the copper diffusion is the rate limiting step which causes the reaction deactivation.

Selective derivatization of oxime-blocked tolylene-2,4-diisocyanate

A selective reaction of cyclohexanone oxime-blocked tolylene-2,4-diisocyanate（2,4-TDI）with amino siloxane was observed,in which amines were capable of discriminating two reactive groups in the 2,4-TDI molecule.Thus,tolylene-2-tert-butyldimethylsilyloxyethyl carbamide-4-cyclohexanone oxime carbamate was synthesized and its precise structure was determined by single-crystal X-ray diffraction.Moreover,it was found that oxime-blocked isocyanate could react selectively with the–NH2group with the–OH group unprotected in ethanolamine.

Selective oxidation of methane and carbon deposition over Fe_2O_3/Ce_(1-x)Zr_xO_2 oxides

A series of Fe2O3/Al2O3, Fe2O3/CeO2, Ce0.7Zr0.3O2, and Fe2O3/Ce1-xZrxO2（x = 0.1–0.4） oxides was prepared and their physicochemical features were investigated by X-ray diffraction（XRD）, transmission electron microscope（TEM）, and H2-temperature-programmed reduction（H2-TPR） techniques. The gas–solid reactions between these oxides and methane for syngas generation as well as the catalytic performance for selective oxidation of carbon deposition in O2-enriched atmosphere were investigated in detail. The results show that the samples with the presence of Fe2O3show much higher activity for methane oxidation compared with the Ce0.7Zr0.3O2solid solution,while the CeO2-contained samples represent higher CO selectively in methane oxidation than the Fe2O3/Al2O3sample. This suggests that the iron species should be the active sites for methane activation, and the cerium oxides provide the oxygen source for the selective oxidation of the activated methane to syngas during the reaction between methane and Fe2O3/Ce0.7Zr0.3O2. For the oxidation process of the carbon deposition, the CeO2-containing samples show much higher CO selectivity than the Fe2O3/Al2O3sample, which indicates that the cerium species should play a very important role in catalyzing the carbon selective oxidation to CO. The presence of the Ce–Zr–O solid solution could induce the growth direction of the carbonfilament, resulting in a loose contact between the carbon filament and the catalyst. This results in abundant exposed active sites for catalyzing carbon oxidation, strongly improving the oxidation rate of the carbon deposition over this sample. In addition, the Fe2O3/Ce0.7Zr0.3O2also represents much higher selectivity（ca. 97 %） for the conversion of carbon to CO than the Fe2O3/CeO2sample, which can be attributed to the higher concentration of reduced cerium sites on this sample. The increase of the Zr content in the Fe2O3/Ce1-xZrxO2samples could improve the reactivity of the materials for methane oxidation, but it also reduces the selectivity for CO formation.

含双晶格氧的无定形锆掺杂锰氧化物选择性高效氧化5-羟甲基糠醛为2,5-呋喃二羧酸

晶格氧介导的氧化还原反应可以将有机物选择性氧化为高附加值产物,是实现生物质资源高值化利用的重要途径.其关键科学难题在于:如何使催化材料同时具有较低的晶格氧(O_(L))结合能以产生活性O_(L),以及较高的O_(L)结合能以保持其在催化过程中的结构稳定性.在本工作中,我们制备了无定形锆掺杂的锰氧化物(amor-Zr:MnO_(x))催化材料,并证实其同时具有高活性的O_(L)以及高稳定性的O_(L).以5-羟甲基糠醛(HMF)的选择性氧化为反应模型,amor-Zr_(0.2)MnO_(x)催化剂实现了HMF的高效选择性氧化,产物中2,5-呋喃二甲酸(FDCA)的选择性高达99%,1小时内FDCA产率高达3600μmol_(FDCA)g_(cat)^(-1)h^(-1),在类似反应条件下其性能优于大多数Mn基和相关过渡金属氧化物基催化材料.实验和理论研究表明,amor-Zr:MnO_(x)的优异性能源于其同时含有两种O_(L).首先,锆提高了锰相邻的O_(L)的氧化活性,并促进了反应后氧空位对O_(2)的吸附/活化,获得活性O_(L)且同步促进催化反应中O_(L)的再生;锆相邻的O_(L)具有较低的反应活性,有利于催化材料保持结构稳定性.本工作有望为理解晶格氧的氧化机制以及高活性催化材料的设计提供思路.

Single Atom Catalysts in Liquid Phase Selective Hydrogenations

Single atom catalysts(SACs)offer exceptional atom efficiency,activity,and selectivity for many catalytic systems.In recent years,SACs have demonstrated great potential in liquid phase selective hydrogenation.In this review,we discuss the critical challenge of selective hydrogenation reactions.Meanwhile,we highlight recent achievements in the design and construction of SACs,as well as their application in liquid reactions.Finally,the current issues and future opportunities for development in the field of SACs are given.

1T-phase MoS_(2)edge-anchored Pt_(1)-S_(3)active site boosting selective hydrogenation of biomass-derived maleic anhydride

Selective hydrogenation of biomass-derived maleic anhydride(MAH)to succinic anhydride(SA)is valuable but remains a challenge due to the complicated reaction network.We here report that single Pt atoms decorated onto the edges of two-dimensional(2D)1Tphase MoS_(2)(Pt1/1T-MOS_(2)SAC)as a proof-of-concept catalyst can efficiently convert biomass-derived MAH to SA with 100%conversion and 100%selectivity under mild conditions.The kinetic data and characterization results suggest that the catalytic performance of the edge-anchored Pt1/1T-MoS_(2)SAC originates from the facile H_(2)dissociation induced by the electron-deficient Pt1atoms and the pocket-like configuration of Pt1active site confines the adsorption configuration of MAH by the steric effect.The strategy of fabricating edge-confined catalysts offers a new direction to design novel SACs for biomass-derived transformations.