Phase-type Fresnel zone plate with multi-wavelength imaging embedded in fluoroaluminate glass fabricated via ultraviolet femtosecond laser lithography

Herein, we report a novel optical glass material, fluoroaluminate (AlF3) glass, with excellent optical transmittance from ultraviolet to infrared wavelength ranges, which provides more options for application in optical devices. Based on its performance, the phase-type Fresnel zone plate (FZP) by ultraviolet femtosecond (fs) laser-inscribed lithography is achieved, which induces the refractive index change by fs-laser tailoring. The realization of ultraviolet fs-laser fabrication inside glass can benefit from the excellent optical performance of the AlF3 glass. Compared with traditional surface-etching micro-optical elements, the phase-type FZP based on AlF3 glass exhibits a clear and well-defined geometry and presents perfect environmental suitability without surface roughness problems. Additionally, optical focusing and multi-wavelength imaging can be easily obtained. Phase-type FZP embedded in AlF3 glass has great potential applications in the imaging and focusing in glass-integrated photonics, especially for the ultraviolet wavelength range.Published versio

Silicalite-1 formation in acidic medium: synthesis conditions and physicochemical properties

International audienceZeolites are the catalytic materials that are widly applied in the processing of conventional and renewable fuels and chemicals. The present study provides a comprehensive analysis of the factors controlling the acidic medium synthesis of high silica silicalite-1 zeolite. The effect of various silica sources (TEOS, fumed and colloidal silica) and alkali metal cations (Na and K) on the silicalite-1 formation is studied. The efficiency of different types of seeds (micron-sized, nanosized, and silicalite-1 amorphous colloidal precursor) on the silicalite-1 crystal growth kinetics and crystal size formed under acidic conditions is also investigated. Further, the zeolite crystallization kinetics under acidic, neutral, and basic conditions is compared. The obtained highly crystalline samples are used to compare the physicochemical properties of zeolites synthesized in acidic, neutral, and basic medium. Thus, the crystallinity, thermal stability, and local order in silicalite-1 samples synthesized in the (2-12) pH range are evaluated

Boosting the Catalytic Activity and Stability of Ru Metal Clusters in Hydrodeoxygenation of Guaiacol through MWW Zeolite Pore Constraints

International audienceThe liquid-phase hydrodeoxygenation (HDO), catalyzed by metal or metal-acid sites, provides an effective catalytic strategy to remove oxygen-containing functionalities of lignin-derived phenolic compounds on the route to fuels and chemicals. Developing the catalyst with high activity and stability is crucial for such a chemical process but still remains a significant challenge. In this contribution, highly dispersed subnanometric Ru metal clusters (< 1.5 nm) encapsulated in the cavities of MWW zeolites, including MCM-22 and its siliceous analog ITQ-1, have been developed for the HDO of guaiacol, an important lignin-derived phenolic monomer, in an apolar liquid phase under mild conditions (160°C, 3 MPa H2). We validate the effective encapsulation of Ru metal clusters in ITQ-1 and HMCM-22 zeolites cavities via complementary characterization methods. The detailed reaction pathways of the HDO of guaiacol are depicted by using guaiacol, phenol, and anisole as reactants. The subnanometric Ru metal clusters confined in MWW zeolite thin layers (20-30 nm in thickness) show remarkable enhancement in HDO activity compared to the large metal particles. The close proximity between Ru metal clusters and Brønsted acid sites (BAS) confined in zeolite constraints delivers a synergistic effect, leading to an additional enhancement in catalytic activity as well as product selectivity. The super stability of the ultrafine Ru metal clusters against sintering and leaching after successive catalytic runs is achieved. The well-defined mono-or bi-functional Ru-containing MWW zeolite catalysts enable the fundamental understanding of HDO of lignin-derived phenolic compounds in the apolar liquid phase and 2 also provide a prototype for the design of superior catalysts for the other energy-related transformations

Boosting the Catalytic Activity and Stability of Ru Metal Clusters in Hydrodeoxygenation of Guaiacol through MWW Zeolite Pore Constraints

Liquid-phase hydrodeoxygenation (HDO), catalyzed by metal or metal-acid sites, provides an effective catalytic strategy to remove oxygen-containing functionalities of lignin-derived phenolic compounds on the route to fuels and chemicals. Developing the catalyst with high activity and stability is crucial for such a chemical process but still remains a significant challenge. In this contribution, highly dispersed subnanometric Ru metal clusters (<1.5 nm) encapsulated in the cavities of MWW zeolites, including HMCM-22 and its siliceous analog ITQ-1, have been developed for the HDO of guaiacol, an important lignin-derived phenolic monomer, in an apolar liquid phase under mild conditions (160 °C, 3 MPa H2). We validate the effective encapsulation of Ru metal clusters in ITQ-1 and HMCM-22 zeolite cavities via complementary characterization methods. The detailed reaction pathways of the HDO of guaiacol are depicted by using guaiacol, phenol, and anisole as reactants. The subnanometric Ru metal clusters confined in MWW zeolite thin layers (20–30 nm in thickness) show remarkable enhancement in HDO activity compared to the large metal particles. The close proximity between Ru metal clusters and Brønsted acid sites (BAS) confined in zeolite constraints delivers a synergistic effect, leading to an additional enhancement in catalytic activity as well as product selectivity. The super stability of the ultrafine Ru metal clusters against sintering and leaching after successive catalytic runs is achieved. The well-defined mono- or bifunctional Ru-containing MWW zeolite catalysts enable the fundamental understanding of HDO of lignin-derived phenolic compounds in the apolar liquid phase and also provide a prototype for the design of superior catalysts for other energy-related transformations

Enhancing the Activity and Thermal Stability of Nickel Complex Precatalysts Using 1‑[2,6-Bis(bis(4-fluorophenyl)methyl)-4-methyl phenylimino]-2-aryliminoacenaphthylene Derivatives

The series of acenaphthylene-1-[2,6-bis­(bis­(4-fluorophenyl)­methyl)-4-methylphenylimino]-2-arylimine derivatives and their dichloronickel complexes were synthesized and fully characterized as well as the single-crystal X-ray diffraction of representative nickel complexes, revealing a distorted tetrahedral geometry. Upon activation with either MAO or Et₂AlCl, all nickel complexes showed high activities in ethylene polymerization; moreover, their catalytic systems showed better thermal stabilities on being manipulated at 80 °C as the industrial operating temperature