Hydrocarbon detection with metal oxide semiconducting gas sensors modified by overlayer or admixture of zeolites Na-A, H-Y and H-ZSM-5

Abstract

A control thick-film SnO 2 gas sensor was modified with zeolites holding LTA, FAU and MFI frameworks using two different approaches to integrate them into the gas-sensing interface. The objective was to prompt selectivity and sensitivity enhancements that were otherwise unattained with the unmodified material when detecting a range of hydrocarbon vapours with similar molecular structures and kinetic diameters. Molecules with different functional groups were also explored. Overlayers were designed by screen-printing 1 or 3 zeolite depositions on top of the control sensor. Admixtures were prepared by screen-printing composites of the control material with 10 % (w/w) and 30 % (w/w) of zeolite. Tests were performed against ethane, propane, butane, ethanol, isopropanol, acetone, toluene and carbon monoxide at concentrations in the 2.5-125 ppm range and sensors were heated to temperatures in the 250-500 °C range. Sensors were also exposed to humid air and to a mixture of ethane and humid air to assess the selective capabilities of the sensing materials in mixed-gas environments. Both fabrication methods provided sensor responses that, combined, favoured vapour discrimination in a way unachievable with the control sensor and the presence of zeolite was seen to assist in sensitivity and selectivity enhancements towards vapours, whilst providing stable and repeatable responses over time.

Porous Ceramic Sensors: Hydrocarbon Gas Leaks Detection

“…In this regard, the sorption and catalytic properties of zeolites can improve the response of sensor and make it sensitive or insensitive to specific species. Layers of different porous zeolites such as silicalite, zeolite A, ZSM-5, LTA onto metal oxides (SnO 2 , WO 3 , and Cr 2 O 3 ) have been assessed [9][10][11][12]. Seeding process and screen printing deposition seem to be common methodologies for fabrication of zeolite films onto metal oxides.…”

Application of levitation-jet synthesized nickel-based nanoparticles for gas sensing

“…That is, when supplied with an inflammable gas they will increase in resistance and, in the presence of an oxidising gas, they will decrease in resistance. The literature sometimes reports variations of this expected behaviour [60][61][62][63].…”

A review on recent developments and advances in environmental gas sensors to monitor toxic gas pollutants

“…57 Parkin et al also developed a novel sensor array by modifying the SnO 2 sensor with several types of zeolites, which exhibited excellent selectivity for hydrocarbon vapors independent of molecular structure, kinetic diameter, or functional group similarity. 58 In addition to zeolites, organic polyolefins and thermoplastic membranes were also used to enhance metal oxide selectivity based on theoretical considerations of membrane properties. Theoretical and experimental studies have shown that p-type oxide semiconductors have different catalytic activities, surface reactivity, and electrical characteristics.…”