Search

Production of polyols and other chemicals from cellulose was important for sustainable society, and it had long relied on the design of suitable catalysts to achieve high yield of lower polyols. Herein, we reported a new preparing strategy for nickel-tungsten catalyst to fabricate Ni-W/SiO2@C catalysts coated by thin carbon. The crystal carbon demonstrated the recommendable confinement effect to obtain the well dispersed metallic particles on SiO2. The prepared composites were characterized by means of XRD, N2 physisorption, thermogravimetry, XPS, TEM, element mapping and atomic force microscope. These characterizations confirmed that more phases including WO3, Ni, NiW alloys and NiC were formed by incorporation of porous crystal carbon. Moreover, the metallic particles were dispersed in size range of 2-8 nm influenced by coating carbon and ethanediamine (dispersant). The activities of catalysts were evaluated in hydrogenolysis of cellulose to lower polyols at 240 °C under 5.0 MPa H2 pressure in the presence of water. Results showed that catalyst Ni-W/SiO2@C-12 was more favorable for EG production, with the highest EG yield of 60.7% and 100% cellulose conversion after reaction for 60 min.Graphical Abstract: The series of high efficient nickel-tungsten catalysts Ni-W/SiO2@C were fabricated and coated by thin carbon. The thin coating carbon demonstrated the recommendable confinement effect to obtain the well dispersed metallic particles on SiO2. [ABSTRACT FROM AUTHOR]

We report a water medium-assisted composite laser cutting (WMACLC) technology for what is believed to be the first time to achieve single-pass separation of frosted glass (FG). The water medium was used to flatten the surface of FG to reduce the diffuse reflection and random refraction of the incident laser. The simulation results of picosecond pulsed laser Bessel beam (PPLBB) intensity distribution in FG showed that the peak intensity in the presence of water can reach about 24 times and 2.3 times that in the absence of water when the PPLBB is 0.08 mm and 0.3 mm below the upper surface of FG, respectively. A PPLBB with higher intensity can be formed along the thickness direction to realize the material modification. A coaxial CW laser provides the thermal tensile stress required for separation. Finally, high-quality separation of FG was achieved using the WMACLC technology with a speed of 50 mm/s. No deviation in the separation track and no edge collapse occurred. The roughness Sa of the separated sidewall is less than 0.3 µm.

Five-axis laser scanning technology is an effective drilling method for special-shaped holes. Due to a gap in laser angle-of-incidence (AOI) control within a large scanning field, current technologies are challenging for fabricating large-size holes or special-shaped hole arrays. In this paper, a large scanning field five-axis laser concurrent drilling system was proposed. The laser AOI was independently controlled using two pairs of synchronous deflection mirrors. The laser control deviations under a large scanning field were investigated systematically by simulation and experiment. By establishing a complete correction method, the laser AOI control within a scanning field diameter of up to 35 mm was achieved. A series of special-shaped holes were fabricated concurrently on a 3.6 mm thick glass fiber reinforced plastic (GFRP), verifying that the AOI can be controlled by the five-axis laser scanning system. Our work provides a novel method to increase the scanning field of the five-axis laser scanning technology, expanding the application scope of the five-axis laser processing.