New Paper CRAPC:Porous Silica Monolithic Polymers for Micromachined Gas Chromatography Columns: A Featured Phase for Fast and Efficient Separations of Light Compounds Mixtures

New Paper CRAPC:Porous Silica Monolithic Polymers for Micromachined Gas Chromatography Columns: A Featured Phase for Fast and Efficient Separations of Light Compounds Mixtures

À LA UNE, CRAPC News, Publication Scientifique, Publication Scientifique Division Santé

Published in: IEEE Sensors Journal ( Volume: 20, Issue: 22, Nov.15, 15 2020)

Porous Silica Monolithic Polymers for Micromachined Gas Chromatography Columns: A Featured Phase for Fast and Efficient Separations of Light Compounds Mixtures

Authors


Imadeddine Azzouz

ESIEE Engineering, Noisy-le-Grand, France

Research Centre in Analytical Chemistry and Physics (CRAPC), Algiers, Algeria

Djahida Lerari

Materials Chemistry Division, Research Centre in Analytical Chemistry and Physics (CRAPC), Algiers, Algeria

Khaldoun Bachari

Research Centre in Analytical Chemistry and Physics (CRAPC), Algiers, Algeria

Abstract:

Since the late 1970s, approaches have been proposed to replace conventional gas chromatography apparatus with silicon-based microfabricated separation systems. Performances are expected to be much improved with miniaturization owing to the reduction of diffusion distances and better thermal management. When it is easy to microfabricate miniaturized parts, the main challenge consists, however, to produce stable, efficient, and functionalized columns. The purpose of the paper is to transpose and adapt monolith synthesis in-situ micromachined gas chromatography columns. Silica-based monolithic microcolumns based on the sol–gel process were tested in the course of high-speed gas chromatographic separations of light hydrocarbons mixture (C1–C4). At the optimum separation conditions, a very good resolution (2.14) for very light compounds (C1–C2) was reached on a 50 cm microcolumn at room temperature with a back-pressure within the range used at gas chromatography facilities (without external modification of the device). The versatility of these microelectromechanical systems (MEMS) columns was demonstrated with a high-temperature C1 – C2 separation, and unsaturated cyclic alkanes. Light halogenated alkanes were also successfully separated. These columns should be used in various applications related to oil/gas and environment field analyses.

https://ieeexplore.ieee.org/abstract/document/9130702/authors

New Paper CRAPC : Spherical NiCu phyllosilicate photocatalysts for hydrogen generation

New Paper CRAPC : Spherical NiCu phyllosilicate photocatalysts for hydrogen generation

À LA UNE, Publication Scientifique, Publication Scientifique Division Santé

International Journal of Hydrogen Energy

Available online 18 November 2020

Spherical NiCu phyllosilicate photocatalysts for hydrogen generation

Author links open overlay panel

Imane Ghiata Adel Saadia Khaldoun Bacharib Neil J.Covillec Amel Boudjemaaab

a Laboratory of Natural Gas, Faculty of Chemistry, USTHB, Algiers, Algeria

b Centre de Recherche Scientifique et Technique en Analyses Physico-Chimiques, Bou-Ismail CP, 42004, Tipaza, Algeria

c DSI-NRF Centre of Excellence in Strong Materials and the Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, Johannesburg, 2050, South Africa

Abstract

To enhance the photocatalytic performance of semiconductors, a highly active and durable SiO2@xNiCuPS photocatalyst was evaluated for photocatalytic hydrogen generation. The photocatalyst was prepared by a hydrothermal method using SiO2 spheres, and a 1:1 Cu:Ni mixture (5 and 10 wt%). The reaction gave a highly stable phyllosilicate material with a core@shell structure. The materials were characterized by a range of techniques. DRS data revealed indirect optical transitions at 1.5 eV and 2.75 eV for the SiO2@5NiCuPS and SiO2@10NiCuPS materials. The new photocatalysts were successfully tested for hydrogen generation under visible irradiation to give H2 yields of 184 and 47 μmol g−1. min−1 for SiO2@5NiCuPS and SiO2@10NiCuPS, respectively. The data suggest that the enhanced activity of adding Cu to Ni to form Ni/Cu phyllosilicates is not due to NiCu alloy formation but due to changes in the support morpholohgy brought about by metal-support interactions. The catalysts were stable over 4 repeat reaction cycles.

Keywords

Hydrogen Photocatalysis NiCu nanoparticles core@shell material

https://www.sciencedirect.com/science/article/abs/pii/S0360319920340817?fbclid=IwAR1vgDZPfcyH0LxEy92jKtUJrHV4yapXR0f0jCYACoYiz9Y_KCRF45WrOGc