Reinforced SIL-1 micromembranes integrated on chip: Application to CO2 separation

Abstract

A novel 4-step microfabrication process is proposed in this work to prepare arrays of coriented silicalite (SIL-1) micromembranes on customized silicon nitride (Si 3 N x) microsieves. The arrays are integrated on chip and their overall porosity values can be tuned from 1.6% to 19.9%. A low stress Si 3 N x microfabricated sieve has been used as support to reinforce via mechanical interlocking and to reduce the effects of the residual stress during membrane processing. The secondary hydrothermal growth over the Si 3 N x microsieves also changes the SIL-1 chemistry, improving its affinity towards CO 2 adsorption. As a result, the SIL-1/Si 3 N x micromembranes integrated on chip facilitate the preferential permeation of CO 2 in CO 2 /H 2 mixtures, showing a maximum CO 2 /H 2 separation factor of 16.9 and a CO 2 permeance of 8.2•10-7 mol•m −2 •s −1 •Pa −1 at ambient conditions.

Zeolite based microconcentrators for volatile organic compounds sensing at trace-level: fabrication and performance

“…Before the anodic bonding step (step E), the processing wafer is exposed at 480 °C for 8 h in an electrical furnace for zeolite activation, i.e. to release the porous framework of the silicalite-1 layer [29,30]. The prefabricated Si wafer is sealed with a Borofloat cover (Siegert Wafer GmbH) 500 ± 20 μm thick by anodic bonding at 1000 V-350 °C.…”

“…Given the interesting properties of zeolite coatings, significant efforts has been devoted to combine the experience gathered in growing zeolite films and the fabrication methods used in the electronic industry [28] to prepare zeolite based microdevices on Si wafers following standard microfabrication schemes. Thus, zeolite only microcantilevers and zeolite micromembranes on customized silicon nitride microsieves have been successfully accomplished [29][30] and demonstrated for VOC detection and CO 2 separation, respectively.…”

Pt based catalytic coatings on poly(benzimidazole) micromonoliths for indoor quality control

“…Mostly, the solutions have generally aimed towards the deposition of thin catalytic coatings on the reactor wall [22]. Given the unique properties of microporous zeolites and related materials, significant efforts have been carried out in our group to combine the experience gathered in growing zeolites and the fabrication methods used in the IC industry to prepare microstructured supports with new functionalities [23][24][25]. In particular, Si substrates providing external area for the zeolite films around 300000-750000 m 2 /m 3 of reactor volume have been tested for VOC catalytic removal due to mass transfer limitations are controlling the reaction rate [26][27].…”