Acidic ZSM-5 Zeolite-Coated Long Period Fiber Grating for Optical Sensing of Ammonia

Abstract

A ZSM-5 zeolite thin film with Si/Al ratio of about 23 has been grown on a long period fiber grating (LPFG) for optical gas sensing by monitoring its resonance wavelength (λR) shift caused by molecular sorption into the zeolite cavity. The sensing selectivity, sensitivity and speed of response of the zeolite-coated LPFG (Z-LPFG) are determined by the adsorption equilibria and transport properties of the analyte molecules in the zeolite pores. The ZSM-5 zeolite was modified through ammonium ion exchange and subsequent calcination to form acidic ZSM-5 (H-ZSM-5). The surface acidified Z-LPFG (HZ-LPFG) achieved dramatically improved sensitivity and selectivity for detecting ammonia gas. Also, increasing operation temperature improves sensing selectivity for the strongly adsorbing ammonia over weakly adsorbing gases and enhances response speed but compromises detection sensitivity due to reduced amount of adsorption for ammonia.

Department(s)

Electrical and Computer Engineering

Sponsor(s)

National Science Foundation (U.S.)
United States. Department of Energy

Keywords and Phrases

ZSM-5 Zeolite Thin Film; Long Period Fiber Grating

International Standard Serial Number (ISSN)

0959-9428

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2011 Royal Society of Chemistry, All rights reserved.

Publication Date

01 Jan 2011

Link to Full Text

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