Comparative catalytic study on butene/isobutane alkylation over LaX and CeX zeolites: The influence of calcination atmosphere

Lanthanum-containing(LaX)and cerium-containing X zeolites(CeX)were prepared by a doubleexchange,double-calcination method.By changing the calcination atmospheres between nitrogen and air,the Ce^(IV) contents in CeX zeolites were adjusted and their impacts on physicochemical properties and catalytic performance in isobutane alkylation were established.The crystallinity of CeX zeolite was found to be negatively correlated with the Ce^(IV) content.This i s believed to be due to the water formed during the oxidation of Ce^(III),which facilitates the framework dealumination.As a consequence,calcining in air resulted in a great elimination of strong Brønsted acid sites while under nitrogen protection,this phenomenon was mostly hindered and the sample’s acidity was preserved.When tested in a continuously flowed slurry reactor,the catalyst lifetime for isobutane alkylation was found to be linearly related to the strong Brønsted acid concentration.In addition,Ce^(3+)was found more benefit for the hydride transfer compared with La^(3+),which is ascribed to the stronger polarization effect on the CH bond of isobutane.Moreover,the decline of hydride transfer activity can be slowed down by the catalytic cracking of the bulky molecules.Based on the product distribution,a new catalytic cycle of dimethylhexanes(DMHs)involving a direct formation of isobutene rather than tert-butyl carbocation was proposed in isobutane alkylation.

Synthesis of propylene glycol ethers from propylene oxide catalyzed by environmentally friendly ionic liquids

A series of acetate ionic liquids were synthesized using a typical two‐step method.The ionic liquids were used as environmentally benign catalysts in the production of propylene glycol ethers from propylene oxide and alcohols under mild conditions.The basic strengths of the ionic liquids were evaluated by determination of their Hammett functions,obtained using ultraviolet‐visible spectroscopy,and the relationship between their catalytic activities and basicities was established.The catalytic efficiencies of the ionic liquids were higher than that of the traditional basic catalyst NaOH.This can be attributed to the involvement of a novel reaction mechanism when these ionic liquids are used.A possible electrophilic‐nucleophilic dual activation mechanism was proposed and confirmed using electrospray ionization quadrupole time‐of‐flight mass spectrometry.In addition,the effects of significant reaction parameters such as concentration of catalyst,molar ratio of alcohol to propylene oxide,reaction temperature,and steric hindrance of the alcohol were investigated in detail.

Simulation and design of a heat-integrated double-effect reactive distillation process for propylene glycol methyl ether production

A double-effect reactive distillation(DERD)process was proposed for the production of propylene glycol methyl ether from propylene oxide and methanol to overcome the shortcoming of low selectivity and high-energy consumption in the tubular plug-flow reactor.A single-column reactive distillation(RD)process was conducted under optimized operating conditions based on sensitivity analysis as a reference.The results demonstrated that the proposed DERD process is able to achieve more than 95%selectivity of the desired product.After that,a design approach of the DERD process with an objective of the minimum operating cost was proposed to achieve further energy savings in the RD process.The proposed DERD configuration can provide a large energy-savings by totally utilization of the overhead vapor steam in the high-pressure RD column.A comparison of the single-column RD process revealed that the proposed DERD process can reduce the operating cost and the total annual cost of 25.3%and 30.7%,respectively,even though the total capital cost of DERD process is larger than that of the RD process.

Progress of vanadium phosphorous oxide catalyst for n-butane selective oxidation

The utilization of lighter alkanes into useful chemical products is essential for modern chemistry and reducing the CO_(2)emission.Particularly,n-butane has gained special attention across the globe due to the abundant production of maleic anhydride(MA).Vanadium phosphorous oxide(VPO)is the most effective catalyst for selective oxidation of n-butane to MA so far.Interestingly,the VPO complex exists in more or less fifteen different structures,each one having distinct phase composition and exclusive surface morphology and physiochemical properties such as valence state,lattice oxygen,acidity etc.,which relies on precursor preparation method and the activation conditions of catalysts.The catalytic performance of VPO catalyst is improved by adding different promoters or co-catalyst such as various metals dopants,or either introducing template or structural-directing agents.Meanwhile,new preparation strategies such as electrospinning,ball milling,hydrothermal,barothermal,ultrasound,microwave irradiation,calcination,sol-gel method and solvothermal synthesis are also employed for introducing improvement in catalytic performance.Research in above-mentioned different aspects will be ascribed in current review in addition to summarizing overall catalysis activity and final yield.To analyze the performance of the catalytic precursor,the reaction mechanism and reaction kinetics both are discussed in this review to help clarify the key issues such as strong exothermic reaction,phosphorus supplement,water supplement,deactivation,and air/n-butane pretreatment etc.related to the various industrial applications of VPO.

Impact of assimilating FY-3C MWHS2 data in the RMAPS-ST forecast system on its rainfall forecasts

In order to evaluate the impact of assimilating FY-3C satellite Microwave Humidity Sounder(MWHS2)data on rainfall forecasts in the new-generation Rapid-refresh Multi-scale Analysis and Prediction System–Short Term(RMAPS-ST)operational system,which is developed by the Institute of Urban Meteorology of the China Meteorological Administration,four experiments were carried out in this study:(i)Coldstart(no observations assimilated);(ii)CON(assimilation of conventional observations);(iii)FY3(assimilation of FY-3C MWHS2 only);and(iv)FY3+CON(simultaneous assimilation of FY-3C MWHS2 and conventional observations).A precipitation process that took place in central-eastern China during 4–6 June 2019 was selected as a case study.When the authors assimilated the FY-3C MWHS2 data in the RMAPS-ST operational system,data quality control and bias correction were performed so that the O-B(observation minus background)values of the five humidity channels of MWHS2 became closer to a normal distribution,and the data basically satisfied the unbiased assumption.The results showed that,in this case,the predictions of both precipitation location and intensity were improved in the FY3+CON experiment compared with the other three experiments.Meanwhile,the prediction of atmospheric parameters for the mesoscale field was also improved,and the RMSE of the specific humidity forecast at the 850–400 hPa height was reduced.This study implies that FY-3C MWHS2 data can be successfully assimilated in a regional numerical model and has the potential to improve the forecasting of rainfall.

Rare earth metal based DES assisted the VPO synthesis for n-butane selective oxidation toward maleic anhydride

Deep eutectic solvents(DESs) are now considered a new class of ionic liquid analogs that have been generously used in various fields.Herein, vanadium phosphorus oxide(VPO) catalysts are synthesized in combination with a deep eutectic solvent containing rare earth metal(rE-DES), and their catalytic performance in n-butane selective oxidation to produce maleic anhydride(MA) is evaluated. The rE-DES is produced from the interaction of choline chloride(ChCl) and rare earth metal salts(Cerium, Europium, Lanthanum, and Samarium metal salt)(ChCl:rE = 1:0.5–1:3) under mild conditions. It was found that DESs served as structural modifiers and electronic promoters during VPO synthesis. It regulated the chemical state of the catalyst surface, such as the vanadium valence state, acid-base properties, and ratios of V^(4+)/V^(5+),Lat–O/Sur–O and P/V. Various characterization techniques, such as FT-IR, DSC, XRD, SEM, EDS, TEM, Raman, TGA, NH3-TPD, and XPS,were used to examine its physical and chemical characteristics. These characteristics were correlated with the catalytic performance. The VPO catalyst modified by rE-DES showed a significant enhancement of n-butane conversion and MA selectivity while suppressing the selectivity of CO and CO_(2)as well as the CO/CO_(2)ratio compared to the unpromoted VPO catalyst. Especially for Ce-DES-VPO, it increased the n-butane conversion and MA mass yield up to approximately 11% and 10%, respectively. In addition, we evaluated the catalytic performance under different activation atmospheres.

Mass transfer characteristics of chiral pharmaceuticals on membrane used for polar organic chemical integrative sampler

Passive sampling technology has good application prospects for monitoring trace pollutants in aquatic environments.Further research on the sampling mechanism of this technology is essential to improve the measurement accuracy and extend the application scope of this approach.In this study,adsorption and permeation experiments were performed to investigate the sorption and mass transfer properties of five chiral pharmaceuticals at the enantiomeric level on polyethersulfone(PES)and polytetrafluoroethylene(PTFE)membranes used in a polar organic chemical integrative sampler.Batch adsorption experiments showed that the PES membrane had an adsorption phenomenon for most selected pollutants and an insignificant sorption behavior was observed for all selected pharmaceuticals on the PTFE membrane except for R(S)-fluoxetine.The diffusion coefficients of selected pharmaceuticals onto the PTFE membrane were approximately one order of magnitude higher than those onto the PES membrane.The permeation experiment indicated that under different hydraulic conditions,the change of the relative pollutant concentration through the PTFE membrane for the composite pollutant system was more obvious than that for the single pollutant system,and mass transfer hysteresis exists for both contaminant systems through PES membranes.Using the first-order equation or 3-component model to estimate the overall mass transfer coefficients,the results showed that the overall mass transfer coefficient values of pollutants in the composite pollutant system onto both membranes were higher than those in the single pollutant system.This parameter was mainly influenced by the synergistic effects of the multi-analyte interaction and diminished water boundary layers during the mass transfer process.

Selective cyclohexane oxidation enhancement by electronic structures regulation of metal-poly(ionic liquid)s

Poly(ionic liquids)(PILs)combined with the macromolecular structure and unique properties of ionic liquids show unlimited potential in catalysis.In this work,a series of metal-based PIL with different ionic ratios were prepared for the selective oxidation of cyclohexane.Characterization analysis reveals that different degrees of ionization could adjust the Co-N sites of the catalysts efficiently,leading to significant changes in their electronic structure,which strongly relate to catalytic performance in oxidation.20.07%cyclohexane conversion and 13.06%cyclohexanone and cyclohexanol(KA oil)yield can be achieved by metal-based PILs that are better than other commercial catalysts.Compared with CoCl_(2),metal-based PILs perform well,with superior conversion and KA oil yield.More interestingly,the catalyst created in this study features a malleable Co-N site,which may potentially have an impact on how oxygen species adsorb and desorb from the catalyst.Therefore,the catalyst studied in this work is used as molecular oxygen for the selective oxidation of cyclohexane to produce KA oil,and its application prospect is promising.

离子液体的环境行为和安全性探讨

由于具有不挥发、不易燃、结构可设计、稳定性高等优势,离子液体被广泛应用于催化、能源、材料制备、生物化工和医药等领域.随着离子液体的大量生产和广泛应用,其对环境的健康风险也日益引起关注.本文对目前离子液体结构进行总结,并分析了其结构对生物安全性的影响规律;探讨了离子液体在不同环境介质中的迁移、转化行为以及可能影响因素;归纳总结了离子液体对陆生生物、微生物、水生生物的影响.对当前离子液体的生物和化学的降解方法进行了综述,研究认为对侧链较短的离子液体,尽量选择化学降解,而对于烷基侧链较长的离子液体,优先选择生物降解.文章进一步阐明对离子液体的环境行为和安全效应以及降解方法进行深入研究具有重要的科学价值,对于客观评价离子液体规模化应用潜力具有十分重要的意义.

Ti/Zr助剂掺杂VPO催化正丁烷选择性氧化制顺酐

采用有机相法制备钒磷氧(VPO)催化剂,并在合成过程中加入Ti/Zr助剂,使用微型固定床反应器评价其催化正丁烷选择性氧化制顺酐的性能,考察了不同助剂元素及其化合物形式和添加量对催化剂性能的影响,分析了添加助剂对催化剂晶相及微观形貌的影响.结果表明,加入助剂未改变催化剂的晶相结构,但促进了活性相(VO)2P2O7生成,且使反应后催化剂微观形貌发生改变,片层更破碎,活性相暴露,同时生成了利于反应的微量V^5+;助剂金属Ti和Zr与V元素间的相互作用对催化剂表面P浓度及V价态都有一定影响;与不加助剂的VPO催化剂相比,相同反应条件下,Ti/Zr助剂修饰的VPO催化性能显著提高,摩尔比Zr/V为1.5%的Zr(NO3)4为助剂的催化剂的催化性能最佳,稳定状态下正丁烷的转化率高达99.1%,顺酐收率为54.4%.

稀土La改性X分子筛催化异丁烷/丁烯烷基化反应

采用液相离子交换法,通过改变交换和焙烧次数制备了5种不同浓度稀土La改性的X分子筛催化剂,使用连续进料的固定床反应器评价其催化异丁烷/丁烯烷基化反应的性能,分析了分子筛物相结构的变化,考察了分子筛的酸性.结果表明,催化剂制备过程对催化剂结构和性能影响显著,La3＋改性后X分子筛结晶度下降,但酸度显著增强,随La^3＋交换次数增加,分子筛的B酸量增多,L酸量减少;5种催化剂中,焙烧前离子交换2次、焙烧后再交换3次、再焙烧所制催化剂催化性能最佳,丁烯的初始转化率为89.94%, C8收率可达66.71%,这归因于酸性增加加快了氢负离子转移,降低了碳正离子上发生重复烷基化的可能性,抑制了大分子生成.反应温度和烯烃空速对反应影响显著,温度从80℃升至100℃,副反应裂解生成的C5-C7从9.64%增加到36.74%;丁烯进料空速从0.1 h^-1降至0.05 h^-1时,低聚生成的C9＋从7.2%增至31%.

离子液体电沉积

离子液体具有电化学窗口宽,热稳定性良好和结构性能可调等独特的物理化学性质,是一种有着广阔应用前景的电沉积介质.本文介绍了离子液体电沉积的发展历程、典型的离子液体电沉积体系结构组成及其中的重要科学问题,并综述了近15年来离子液体电沉积的研究进展.本文详细介绍了五种不同类型离子液体中金属/合金的电沉积过程,包括卤素金属酸盐型离子液体、空气和水稳定型离子液体、低共熔溶剂、含金属阳离子型离子液体和质子型离子液体,并且系统概述了调节因素如沉积条件(电流密度、沉积模式、沉积时间、温度)和电解质成分(阴离子、阳离子、金属盐、添加剂、水分)对于沉积物形貌、组成、微观结构和性质的影响规律.之后,重点介绍了离子液体在半导体电沉积中的研究进展.最后,指出了目前离子液体电沉积在基础理论和技术研究中面临的挑战,并展望了其未来在电子信息领域的发展前景.

Capability of Fengyun-3D Satellite in Earth System Observation

From the viewpoint of earth system science,this paper discusses the observation capability of the second-generation of Chinese polar-orbiting,sun-synchronous operational meteorological satellite observation systems,Fengyun-3(FY-3),based on the function and performance test results from the FY-3 D satellite observation system in orbit.The FY-3 series of satellites have numerous remote sensing instruments and a wide range of imaging and sounding electromagnetic spectrometers onboard.These instruments can obtain reflectivity data for land surface,soil,vegetation,water body,snow cover,ocean color,and sea ice on earth’s surface over a wide spectral range,as well as information on the absorption and scattering radiative transfer of molecules and particles(clouds and aerosols)in earth’s atmosphere.All of these data can be used to retrieve physical and chemical information about the land,ocean,and atmosphere of the earth system.Comprehensive observation of the earth system by the FY-3 meteorological satellites is preliminarily realized.

Degradation of dissolved organic matter in effluent of municipal wastewater plant by a combined tidal and subsurface flow constructed wetland

Dissolved organic matter(DOM)is an important constituent of wastewater treatment plant(WWTP)effluent.A novel combined tidal and subsurface flow constructed wetland(TF-SSFCW)of 90 L was constructed for a ten-month trial of advanced treatment of the WWTP effluent.Excitation emission matrix(EEM)fluorescence spectroscopy,parallel factor(PARAFAC)analysis and a two end-member mixing model were employed to characterize the composition and removal process of the effluent DOM(EfOM)from the WWTP.The results showed that the TF-SSF-CW performed an efficient EfOM removal with dissolved organic carbon(DOC)removal rate of 88%and dissolved organic nitrogen(DON)removal rate of 91%.Further analysis demonstrated that the EfOM consisted mainly of two protein moieties and two humic-like groups;protein moieties(76%)constituted the main content of EfOM in raw water and humic-like groups(57%)became the dominating contributor after treatment.The EfOM from the WWTP was mainly of aquatic bacterial origin and evolved to a higher proportion of terrigenous origin with higher humification in the TF-SSF-CW effluent.A common controlling treatment-related factor for determining the concentrations of the same kind of substances(protein groups or humic-like groups)was revealed to exist,and the ratio of removal rates between the same substances in treatment was calculated.Our study demonstrates that the TF-SSF-CW can be a novel and effective treatment method for the EfOM from WWTPs,and is helpful for understanding of the character of EfOM in wetland treatment.

Stability,acidity and interaction properties of [Bmim][SbF_6] coupled with concentrated sulfuric acid

Ionic liquid coupled with strong acid systems presents considerable promise in some catalytic fields. In the present work, the multiple complex systems composed by 98 wt% concentrated sulfuric acid and [Bmim][SbF6] were investigated in the terms of stability, acidity and interaction properties. It was found that acidolysis of [Bmim][SbF6] occurred in the 98 wt% concentrated sulfuric acid accompanied by HF releasing and SbF6−degrading to [SbF6−y(HSO4)y]−. The species after acidolysis in the multiple complex systems were checked and confirmed by electrospray ionization mass spectrometry (ESI-MS), Fourier transform infrared spectroscopy (FT-IR),1H NMR and19F NMR. Acidity increased slightly with less than 1 wt% [Bmim][SbF6] addition, while decreased with more proportion, which was determined based on the Hammett acidity functions H0, using13C NMR. The strong hydrogen bond S–O–HF of interaction among the multiple complex systems was confirmed by molecular dynamic simulation. © 2017, Science China Press and Springer-Verlag Berlin Heidelberg.

Energy efficiency and area spectral efficiency tradeoff for coexisting wireless body sensor networks

The coexistence of wireless body sensor networks(WBSNs) is a very challenging problem, due to strong interference, which seriously affects energy consumption and spectral reuse. The energy efficiency and spectral efficiency are two key performance evaluation metrics for wireless communication networks. In this paper, the fundamental tradeoff between energy efficiency and area spectral efficiency of WBSNs is first investigated under the Poisson point process(PPP) model and Matern hard-core point process(HCPP) model using stochastic geometry. The circuit power consumption is taken into consideration in energy efficiency calculation. The tradeoff judgement coefficient is developed and is shown to serve as a promising complementary measure. In addition, this paper proposes a new nearest neighbour distance power control strategy to improve energy efficiency. We show that there exists an optimal transmit power highly dependant on the density of WBSNs and the nearest neighbour distance. Some important properties are also addressed in the analysis of coexisting WBSNs based on the IEEE 802.15.4 standard, such as the impact of intensity nodes distribution,optimal guard zone, and outage probability. Simulation results show that the proposed power control design can reduce the outage probability and enhance energy efficiency. Energy efficiency and area spectral efficiency of the HCPP model are better than those of the PPP model. In addition, the optimal density of WBSNs coexistence is obtained.

Metal–Organic Framework-Derived CuS Nanocages for Selective CO_(2) Electroreduction to Formate

Electroreduction of CO_(2) to target products with high activity and selectivity has techno-economic importance for renewable energy storage and CO_(2) utilization.Herein,we report a hierarchical CuS hollow polyhedron(CuS-HP)for electrocatalytic CO_(2) reduction(E-CO_(2)R)in neutral pH aqueous media.Under E-CO_(2)R conditions,CuS-HP undergoes structural reconstruction into sulfur-doped metallic Cu catalyst,which promotes formate production with Faradaic efficiency>90%in a wide potential range.

Development of a correlation equation between the diesterification of maleic anhydride and the acidic ionic liquids nature

The sustainable synthesis of dimethyl maleate via diesterification through the utilization of ionic liquid(IL)is of great importance.However,the relationship between the ILs nature and the reactivity of diesterification is still unclear.Herein,a series of ILs with different structures were selected for the comprehensive investigation of diesterification.The acidity(H_(0))and Kamlet-Taft solvent parameters(hydrogen bond donor ability(α),hydrogen bond acceptor ability(β),and polarizability(π^(*)))of ILs were measured by UV–Visible spectroscopy,and the effects of them on the diesterification of maleic anhydride were also studied in detail.The results indicated that not only H0of the IL-based catalysis system,but also itsα,β,andπ^(*)influenced the reaction activity of diesterification.Furthermore,a quantifiable correlation was fitted between the natural logarithm of the rate constant and multiple parameters of ILs,indicating that the diesterification rate had a positive correlation with the H0,α,andπ^(*),and inverse correlation with theβof the IL.A plausible synergetic reaction mechanism for the excellent performance of[(HSO_(3))PMim][HSO_(4)]has been proposed.Overall,this work thoroughly explored the relationship between the nature of ILs on diesterification in-depth,which will reveal the nature of diesterification in detail.

High potential in synergizing the reduction of dissolved organic carbon concentration and carbon dioxide emissions for submerged-vegetationcovered river networks

Various technologies and projects have been explored and developed for the synergetic control of environmental pollution and carbon emissions in aquatic ecosystems.Planting submerged vegetation in shallow waters was also expected to achieve this purpose.However,the magnitude and mechanism of carbon dioxide(CO_(2))emission affected by submerged vegetation is not clear enough in complex aquatic ecosystems.This study investigated the influences of submerged plants on CO_(2)emission,ecosystem metabolism features,and microbial community traits based on observations in river networks on the Changjiang River Delta.The results showed that CO_(2)emission from planted waters accounted for 73%of unplanted waters.Meanwhile,planted waters had higher dissolved organic carbon removal capacity in overlying water and higher potential of carbon sequestration in sediment at the same time.These distinctions between the two habitats were attributed to(1)improved CO_(2)and bicarbonate consumption in water columns via enhancing photosynthesis and(2)inhibited CO_(2)production by reconstructing the benthic microbial community.Additional eco-advantages were found in planted sediments,such as a high potential of methane oxidation and xenobiotics biodegradation and a low risk of becoming black and odorous.In brief,submerged vegetation is beneficial in promoting pollution removal and carbon retention synchronously.This study advances our understanding of the feedback between aquatic metabolism and CO_(2)emission.

Microwave synthesis of vanadium phosphorus oxide catalysts for n-butane selective oxidation

Vanadium phosphorus oxide (VPO) catalysts play a crucial role in the selective oxidation of n-butane to maleic anhydride (MA), and their catalytic performance is highly dependent on the synthesis conditions of the precursor. This study focuses on a facile and rapid microwave irradiation method for the synthesis of VPO precursors. The effects of microwave exposure time and power on morphology, crystalline structure, and catalytic effect of VPO are investigated. The relationship between the structure and performance of the catalysts is explored by SEM, TEM, BET, FT-IR, XRD, Raman, and XPS characterization. The results demonstrate that microwave power is the key factor influencing the size, thickness, surface area, and active surfaces of vanadium pyrophosphate after activation. Additionally, the P/V ratio and Lat-O/Sur-O ratio on the catalyst surface vary with different synthesis conditions, which significantly affect the catalytic performance. In conclusion, the microwave-synthesized VPO catalyst exhibits remarkable enhancements in n-butane conversion (87.2%) and maleic anhydride (MA) selectivity (70.2%), which shows high efficiency and energy-saving, providing a new research direction for the future preparation of VPO catalysts.