Dealuminated Hβ zeolite for selective conversion of fructose to furfural and formic acid

The fructose-to-furfural transformation is facing major challenges in the selectivity and high efficiency. Herein, we have developed a simple and effective approach for the selective conversion of fructose to furfural using Hβ zeolite modified by organic acids for dealuminization to regulate its textural and acidic properties. It was found that citric acid-dealuminized Hβ zeolite possessed high specific surface areas, wide channels and high Brønsted acid amount, which facilitated the selective conversion of fructose to furfural with a maximum yield of 76.2% at433 K for 1 h in the γ-butyrolactone(GBL)-H_(2)O system, as well as the concomitant formation of 83.0% formic acid. The^(13)C-isotope labelling experiments and the mechanism revealed that the selective cleavage of C1–C2 or C5–C6 bond on fructose was firstly occurred to form pentose or C5 intermediate by weak Brønsted acid, which was then dehydrated to furfural by strong Brønsted acid. Also this dealuminized Hβ catalyst showed the great recycling performance and was active for the conversion of glucose and mannose.

Special Issue on Catalytic Activation and Selective Conversion of Energy-Related Molecules

The activation and selective conversion of energy-related molecules is an important research area of energy chemistry.The depletion of petroleum has stimulated research activities into the utilization of non-petroleum carbon resources such as natural gas(including conventional and

Vortex localization and OAM selective conversion via cylindrical metagratings

Vortex waves with orbital angular momentum(OAM)are a highly active research topic in various fields.In this paper,we design and investigate cylindrical metagratings(CMs)with an even number of unit cells that can efficiently achieve vortex localization and specific OAM selective conversion.The multifunctional manipulation of vortex waves and the new OAM conservation law have further been confirmed through analytical calculations and numerical simulations.In addition,we qualitatively and quantitatively determine the OAM range for vortex localization and the OAM value of vortex selective conversion and also explore the stability for performance and potential applications of the designed structure.This work holds potential applications in particle manipulation and optical communication.

Selective electrocatalytic conversion of methane to fuels and chemicals

The increase in natural gas reserves makes methane a significant hydrocarbon feedstock. However, thedirect catalytic conversion of methane into liquid fuels and useful chemicals remains a great challenge,and many studies have been devoted to this field in the past decades. Electrocatalysis is considered asan important alternative approach for the direct conversion of methane into value-added chemicals, al-though many other innovative methods have been developed. This review highlights recent advances inelectrocatalytic conversion of methane to ethylene and methanol, two important chemicals. The electro-catalytic systems efficient for methane conversions are summarized with an emphasis on catalysts andelectrolytes. The effects of reaction conditions such as the temperature and the acid-base property of thereaction medium are also discussed,

Self-supported porous copper oxide nanosheet arrays for efficient and selective electrochemical conversion of nitrate ions to nitrogen gas

Electrochemical techniques have shown advantages for the removal of low-concentration nitrate.Here,copper oxide nanosheets were grown on self-supporting nickel foam(NF)to prepare electrodes(CuO/NF),which realized the rapid and highly selective conversion of nitrate pollutants in sewage into nontoxic and harmless N_(2).The CuO/NF afforded 100%NO_(3)^(-)removal within 100 min and 99.53%selectivity for N_(2)at-50 mA without producing a lot of by-products(NO_(2)-,NH_(4)^(+),and N_(2)H_(4)).Furthermore,81.8%of NO_(3)^(-)was removed under the given conditions after six experimental repetitions.These results suggest that the cat-alyst has excellent electrochemical stability.The performance of CuO/NF for the electrocatalytic removal of NO_(3)^(-)in simulated wastewater(which contained Cl^(-) and SO_(4)^(2-))was almost unaffected.Because of the high efficiency,high stability,and low cost of CuO/NF,this catalyst is practical for the removal of nitrate for wastewater purification.

Regulating ethane and ethylene synthesis by proton corridor microenvironment for CO_(2) electrolysis

Electrocatalytic reduction of carbon dioxide is one of the most effective strategies to achieve carbon neutrality and energy sustainability.Although high-value multi-carbon products have been widely studied,limited electrocatalysts have been reported for the selective conversion of ethane.More importantly,the factors tuning the selectivity between ethane and ethylene have not been clarified.Here,Zn@Cu nanowire arrays(Zn@Cu-NWAs) catalyst is proposed to stimulate the maintenance of efficient CO_(2)-to-C_(2)H_(6) conversion at high current densities.Meanwhile,in order to investigate the factors affecting the interconversion between ethane and ethylene,the counterpart catalyst that facilitates C–C coupling to ethylene was also synthesized.Time-of-flight secondary-ion mass spectroscopy(TOF-SIMS),in-situ Raman spectroscopy,and simulation results show that Zn@Cu-NWAs can provide a localized proton corridor environment for the formation of ethane,accelerating the further proton-coupled CO_(2) reduction reaction(CO_(2)RR)kinetics.Hence,this catalyst delivered an ethane Faraday efficiency of over 65% at-1.14 V vs.RHE with a total current density of 142.3 mA/cm^(2).This work provides a new perspective on regulating the local microenvironment to modify the selectivity of multi-carbon products.

SAPO-34 facilitates the formation of benzene,toluene and xylenes in direct syngas conversion over MnCrO_(x)-SAPO-34-ZSM-5

Direct conversion of syngas to aromatics over metal oxide and zeolite(OXZEO) composite catalysts is promising.However,the selectivity of more valuable products such as benzene,toluene and xylenes(BTX) is limited due to undesired secondary methylation of BTX.Herein,we report that the introduction of SAPO-34 into MnCrO_(x)-ZSM-5 catalyst enhances significantly the formation of BTX without sacrificing the aromatics selectivity.Under optimized conditions,the fraction of BTX in aromatics reaches 64.7% versus 28.9% over the catalyst without SAPO-34.A number of model reaction tests and characterizations reveal that SAPO-34 consumes partially the intermediates such as ketene,by converting them to light olefins.Thus,the methylation of BTX by ketene to heavy aromatics is inhibited over the external acid sites of ZSM-5,leading to an enhanced BTX selectivity in the products.This hybrid catalyst provides an efficient method for highly selective synthesis of BTX from syngas.

Filterless Photosensors with Intrinsic Color Perception and Flexibility

Sensing materials possessing intrinsic color perception are indispensable prerequisites for the development of filterless photosensors,which could eliminate the need for complex device designs and avoid color distortion in post-processing.Traditional materials are constrained by complex processing methods and limited stability.Herein,a color-photosensitive array based on ionic liquid with selective photothermal conversion(ILSPC)has been developed for intrinsic color perception.Relying on the selective absorption,photothermal conversion,and thermosensitivity of ILSPC,a photo-thermo-electric sensing system has been constructed.Besides,the versatility of the two algorithms has been validated in color reconstruction and electrical signal prediction.As an exploration,the photosensitive array showcases promising color recognition capabilities,potentially propelling the evolution of flexible photosensors.

Synergetic catalysis of ceria and titania for selective reduction of NO

The promotional effect of the interaction between titania and ceria on the catalytic performance for selective reduction of NO was studied.The catalysts,CeO 2,TiO 2,CeO 2 /TiO 2 and Ti x Ce 1-x O 2,were synthesized and tested in NH 3-Selective catalytic reduction（SCR） of NO,and the samples were characterized by the Brunaller,Emmett and Teller（BET absorbed gas N 2）,X-ray diffraction（XRD）,high resolution transmission electron microscopy（HR-TEM）,and temperature programmed desorption（TPD NH 3） techniques.The improvement mechanism of the interaction between the titania and ceria had been explored and discussed from two aspects of micro-structure and surface acidity.The interaction between the titania and ceria greatly improved the catalytic activity but had little effect on the active temperature.It was first reported that the acid amount determined the catalytic activity and the acid strength determined the active temperature for NH 3-SCR of NO.

Hydrochlorination of acetylene using expanded multilayered vermiculite(EML-VMT)-supported catalysts

Catalyst supports have very important effects on catalyst performance.A novel expanded multilayered vermiculite（EML-VMT） is successfully used as the catalyst support for the acetylene hydrochlorination.By mixing carbon on the surface of EML-VMT[i.e.,EML-VMT-C）,the HgCl2/EML-VMT-C achieved a high acetylene conversion of 97.3%,a vinyl chloride selectivity of 100%and a turn over frequency（TOF） value of 8.83 × 10^-3s^-1 at a temperature of 140 C,an acetylene gas hourly space velocity（GHSV） of 108 h^-1,and a feed volume ratio V（HC1）/V（C2H2） of 1.15.Moreover,the HgCl2/EML-VMT-C shows good stability.The EML-VMT also shows potential in the preparation of other EML-VMT-supported catalysts.

La1-xCexMnO3/attapulgite nanocomposites as catalysts for NO reduction with NH3 at low temperature

A series of attapulgite （ATP） supported perovskite-type La1-xCexMnO3 ix=0-0.2） nanocomposites were prepared by a sol-gel method. The samples were characterized by X-ray diffraction, transmission elec- tron microscopy, Fourier-transform infrared spectroscopy, H2 temperature-programmed reduction, and temperature-programmed desorption of NH3. Their selective catalytic reduction of NO with NH3 was evaluated in the low-temperature range. The impact of the doping fraction of Ce4＋ on the NO conversion was investigated. The results indicated that the La1-xCexMnO3 nanoparticles with a size of ca. 15 nm were uniformly immobilized on the surface of ATP with a loading amount of 20wt%. The highest conversion rate of NO reached 98.6% when the doping fraction x was O.1, while the ATP support supplied a high surface areas facilitating the nanoparticles dispersion as well as the gas adsorption. Incorporation of an appropriate amount of Ce4＋ in the La3＋ site resulted in a high degree of reduction by the active perovskite species with enhanced catalytic activity.