Effects of porous oxide layer on performance of Pd-based monolithic catalysts for 2-ethylanthraquinone hydrogenation

Pd/oxide/cordierite monolithic catalysts(oxide = Al_2O_3, SiO_2 and SiO_2\\Al_2O_3) were prepared by the impregnation method. The results of ICP, XRD, SEM–EDX, XPS and N_2 adsorption–desorption measurements revealed that the Pd penetration depth increased with increasing the thickness of oxide layer, and the catalysts with Al_2O_3 layers had the larger pore size than those with SiO_2 and SiO_2\\Al_2O_3 layers. Catalytic hydrogenation of 2-ethylanthraquinone(eA Q), a key step of the H_2O_2 production by the anthraquinone process, over the various monolithic catalysts(60 °C, atmosphere pressure) showed that the monolithic catalyst with the moderate thickness of Al_2O_3 layer(about 6 μm) exhibited the highest conversion of e AQ(99.1%) and hydrogenation efficiency(10.0 g·L^(-1)). This could be ascribed to the suitable Pd penetration depth and the larger pore size, which provides a balance between the distribution of Pd and accessibility of active sites by the reactants.

Investigation on electrocatalytic performance and material degradation of an N-doped grapheneMOF nanocatalyst in emulated electrochemical environments

To develop graphene-based nanomaterials as reliable catalysts for electrochemical energy conversion and storage systems(e.g.PEM fuel cells,metal–air batteries,etc.),it is imperative to critically understand their performance changes and correlated material degradation processes under different operational conditions.In these systems,hydrogen peroxide(H_(2)O_(2))is often an inevitable byproduct of the catalytic oxygen reduction reaction,which can be detrimental to the catalysts,electrodes,and electrolyte materials.Here,we studied how the electrocatalytic performance changes for a heterogeneous nanocatalyst named nitrogen-doped graphene integrated with a metal–organic framework(N-G/MOF)by the effect of H_(2)O_(2),and correlated the degradation process of the catalyst in terms of the changes in elemental compositions,chemical bonds,crystal structures,and morphology.The catalyst samples were treated with five different concentrations of H_(2)O_(2) to emulate the operational conditions and examined to quantify the changes in electrocatalytic performances in an alkaline medium,elemental composition and chemical bonds,crystal structure,and morphology.The electrocatalytic performance considerably declined as the H_(2)O_(2) concentration reached above 0.1 M.The XPS analyses suggest the formation of different oxygen functional groups on the material surface,the breakdown of the material's C–C bonds,and a sharp decline in pyridinic-N functional groups due to gradually harsher H_(2)O_(2) treatments.In higher concentrations,the H_(2)O_(2)-derived radicals altered the crystalline and morphological features of the catalyst.

CuS/RGO hybrid by one-pot hydrothermal method for efficient electrochemical sensing of hydrogen peroxide

In this study,a non-enzymatic hydrogen peroxide sensor was successfully fabricated on the basis of copper sulfide nanoparticles/reduced graphene oxide（CuS/RGO） electrocatalyst.Using thiourea as reducing agent and sulfur donor,CuS/RGO hybrid was synthesized through a facile one-pot hydrothermal method,where the reduction of GO and deposition of CuS nanoparticles on RGO occur simultaneously.The results confirmed that the CuS/RGO hybrid helps to prevent the aggregation of CuS nanoparticles.Electrochemical investigation showed that the as-prepared hydrogen peroxide sensor exhibited a low detection limit of 0.18μmol/L（S/N = 3）,a good reproducibility（relative standard deviation（RSD） of4.21%）,a wide linear range（from 3 to 1215 μmol/L） with a sensitivity of 216.9 μA L/mmol/cm-2 under the optimal conditions.Moreover,the as-prepared sensor also showed excellent selectivity and stability for hydrogen peroxide detection.The excellent performance of CuS/RGO hybrid,especially the lower detection limit than certain enzymes and noble metal nanomaterials ever reported,makes it a promising candidate for non-enzymatic H2O2 sensors.

Selective oxidation of alcohols with H2O2 catalyzed by zinc polyoxometalate immobilized on multi-wall carbon nanotubes modified with ionic liquid

In this work,acid functionalized multi-wall carbon nanotubes（MWCNTs） were modified with imidazolium-based ionic liquids.The selective oxidation of various alcohols with hydrogen peroxide catalyzed by [PZnMo2W9O39]^5-,ZnPOM,supported on ionic liquids-modified with MWCNTs,MWCNTAPIB,is reported.This catalyst[ZnPOM@APIB-MWCNT],was characterized by X-ray diffraction,scanning electron microscopy（SEM） and FT-IR spectroscopic methods.This heterogeneous catalyst exhibited high stability and reusability in the oxidation reaction without loss of its catalytic performance.