Influence of supports for selective production of 2,5-dimethylfuran via bimetallic copper-cobalt catalyzed 5-hydroxymethylfurfural hydrogenolysis

The hydrogenolysis of carbon–oxygen bonds is an important model reaction in upgrading biomass‐derived furanic compounds to transportation fuels.One of these model reactions,namelyconversion of5‐hydroxymethylfurfural(HMF)to the gasoline additive2,5‐dimethylfuran(DMF),isespecially attractive.In this study,bimetallic Cu‐Co catalysts supported on CeO2,ZrO2,and Al2O3were used for the selective hydrogenolysis of HMF to DMF.The structures of the fresh and usedcatalysts were studied using X‐ray diffraction,the Brunauer‐Emmett‐Teller method,transmissionelectron microscopy,temperature‐programmed reduction by H2,temperature‐programmed desorptionof NH3,and CHNS analysis.The structures were correlated with the catalytic activities.TheCu‐Co/CeO2catalyst produced mainly2,5‐bis(hydroxymethyl)furan via reduction of C=O bonds onlarge Cu particles.The Cu‐Co/Al2O3catalyst gave the best selectivity for DMF,as a result of a combinationof highly dispersed Cu,mixed copper–cobalt oxides,and suitable weak acidic sites.Cu‐Co/ZrO2had low selectivity for DMF and produced a combination of variousover‐hydrogenolysis products,including2,5‐dimethyltetrahydrofuran and5,5‐oxybis(methylene)‐bis(2‐methylfuran),because of the presence of strong acidic sites.The reaction pathways and effectsof various operating parameters,namely temperature,H2pressure,and time,were studied to enableoptimization of the selective conversion of HMF to DMF over the Cu‐Co/Al2O3catalyst.

无铬Co-Cu/SBA-15催化剂催化生物质衍生α-,β-不饱和醛加氢制醇（英文）

Cr-free bi-metallic SBA-15-supported Co–Cu catalysts were examined in the conversion of biomass-derived α-, β-unsaturated aldehyde(furfural) to value-added chemical furfuryl alcohol(FOL).Co–Cu/SBA-15 catalysts with a fixed Cu loading of 10 wt% and varying Co loadings(2.5, 5, and 10 wt%) were prepared by the impregnation method. The catalysts were characterized by X-ray diffraction, N2 sorption, H2 temperature-programmed reduction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, high-resolution transmission electron microscopy, CO chemisorption, and inductively coupled plasma mass spectrometry. The influence of different reaction parameters such as temperature, pressure, catalyst dosage, and furfural concentration on the catalyst performance was evaluated. Relative to catalysts supported on amorphous silica, the current SBA-15-supported Co–Cu catalysts displayed higher performance, attaining a furfural conversion of 99% and furfuryl alcohol selectivity of 80%. The catalytic reactions were conducted in a 100-mL autoclave at 170 °C and 2 MPa H2 pressure for 4 h.

Effect of Hot Carrier on Amplitude Modulation and Demodulation of Gaussian High Power Helicon Wave in Homogeneous Longitudinally Magnetized Strain Dependent Dielectric Material

In the present communication, the hydrodynamic model is used to investigate the amplitude modulation as well as demodulation of an electromagnetic wave of high power helicon pump wave into another helicon wave in strain dependent dielectric material incorporating carrier heating (CH) effects. The consideration of CH in modulation and demodulation is prime importance for the adding of new dimension in analysis of amplification of acoustic helicon wave. By using the dispersion relation, threshold pump electric filed and growth rate of unstable mode from the modulation and demodulation of the high power helicon wave well above from the threshold value will be discussed in the present analysis. The numerical analysis is applied to a strain dependent dielectric material, BaTiO3 at room temperature and irradiated with high power helicon wave of frequency 1.78 × 1014 Hz. This material is very sensitive to the pump intensities, therefore during studies, Gaussian shape of the helicon pump wave is considered during the propagation in stain dependent dielectric material and opto-acoustic wave in the form of Gaussian profile (ω0,κ0) is induced longitudinally along the crystallographic plane of BaTiO3. Its variation is caused by the available magnetic field (ωc), interaction length (z) and pulsed duration of interaction (τ). From the analysis of numerical results, the incorporation of CH effect can effectively modify the magnitude of modulation or demodulation of the amplitude of high power helicon laser wave through diffusion process. Not only the amplitude modulation and demodulation of the wave, the diffusion of the CH effectively modifies the growth rate of unstable mode of frequency in BaTiO3. The propagation of the threshold electric field shows the sinusoidal or complete Gaussian profile, whereas this profile is found to be completely lost in growth of unstable mode. It has also been seen that the growth rate is observed to be of the order of 108 - 1010 s-1 but from diffusion of carrier heating, and that its order is enhanced from 1010 - 1012 s-1 with the variation of the magnetized frequency from 1 to 2.5 × 1014 Hz.

Propagation of Acoustic Wave inside the Carbon Nanotube: Comparative Study with Other Hexagonal Material

Carbon nanotube is a novel and more explored material. In this paper, ultrasonic acoustic velocity of the carbon nanotube has been calculated along unique axis at room temperature. For the evaluations of ultrasonic properties, second and third-order elastic constants have been computed from Lennard-Jones interaction potential. Attenuation of ultrasonic waves due to phonon-phonon interaction is predominant over thermoelastic loss. Carbon nanotube shows the unique behavior with the chiral number. Chiral number not only affect the band gap and tube radius of the carbon nanotube but also affect the mechanical properties like stiffness, bulk modulus, shear modulus of the tube. The peculiar behavior is obtained at 55°. Due to their least thermal relaxation time and highest Debye average velocity. Results are also compared with other hexagonal metallic materials which present in periods and group of the periodic table. They show the optimum behavior with other hexagonal materials.

An Experimental Study of Microstructure through SEM and AFM by Interaction from High Power Femtosecond Laser Wave with BaTiO3

This paper deals with the interaction of femtosecond laser with strain dependent high dielectric material. For this investigation, ferroelectric material like BaTiO3 has been chosen because of centrosymmetric structure. Due to irradiation of laser light, the micro-structure of BaTiO3 is found to change along the direction of heat propagation. SEM and AFM tools have been used to detect the morphology and roughness of the femotosecond laser treated BaTiO3. The change of morphology and surface behavior depends upon the laser fluence and intensity of laser light. The maximum change in morphology has been observed at a higher laser fluence.

Tunneling properties of electromagnetic wave in slab su-perconducting material

When the electromagnetic wave propagates through a slab superconducting material in microwave ranges,tunneling properties of the electromagnetic wave at critical temperature are investigated theoretically.The transmittance and the reflectance of the slab superconducting material vary with the thickness of material as well as the refractive index of substrates.The high transmittance is found for thin superconductor at low wavelength region.However,optical properties are strongly dependent upon temperature and incidence wavelength.The electromagnetic wave is totally transmitted without loss for incidence wavelength(l = 5000 nm) due to the zero refractive index and infinite penetration depth of the superconductor at the critical temperature.