Design of Efficient Zeolite Sensor Materials for n-Hexane

Abstract

The effectiveness of several zeolite catalysts was investigated using the cataluminescence (CTL) gas sensor system. Trace amounts of n-hexane in air samples were detected by this method. This research establishes that the specific pore size of the zeolite offers designable environment for selective CTL reaction, and "Lewis-type" basic sites appear to contribute to the catalytic nature of the zeolite surface. By incorporating either Cs+ or K+, the velocity and luminescence intensity of these catalytic reactions increase while going from Na to Cs, according to the basic nature of this group of cations in the following order: Cs > K > Na. The proposed sensor shows high sensitivity and selectivity to n-hexane at a mild reaction temperature of 225 degrees C. Quantitative analysis was performed at a selected wavelength of 460 nm. The linear range of CTL intensity versus concentration of n-hexane was 0.776-23.28 microg/mL (R = 0.997, n = 7) on CsNaY, and 0.776-23.28 microg/mL (R = 0.998, n = 7) on CsNaX, with a detection limit of 0.155 microg/mL (signal-to-noise ratio 3). Interferences from foreign substances such as methanol, ethanol, 2-propanol, acetone, acetonitrile, chloroform, or dichlormethane and other alkanes, aromatics, and alkyl aromatics such as methane, n-pentane, 3-methylpentane, 3,3-dimethylpentane, methylbenzene, ethylbenzene, and sec-butylbenzene were very low or not detectable. Results of a series of GC and GC/MS experiments suggest that the possible mechanism of the reaction is the formation of an unstable transition structure with a four-member ring, and this ring most probably consists of an oxygen atom and a carbonium ion localized on the zeolite suface.

Advances in nanomaterial-assisted cataluminescence and its sensing applications

“…Borrowing ideas from classical catalytic reaction theory is another choice, which helps us obtain a quick understanding, but is not always successful. For example, Yang et al [37] successfully utilized carboniogenesis theory to make a reasonable guess regarding the reaction route based on GC-MS assay. Our research group [38] demonstrated the successful introduction of theoretical calculation into the study of CL mechanisms of the oxidation of ethyl ether, in not only clarifying the main route for CL emission and in the prediction of the main CL intermediates, such as CH 3 CO• with good agreement with experimental data, but also interpreting the key roles of oxygen and reaction temperature.…”

“…For example, in Tables 1 and 2, Nakagawa and co-workers established the CTL gas sensors using classic catalysts γ-Al 2 O 3 and γ-Al 2 O 3 :Dy 3+ as sensing materials, together with a temperature-gradient technique, and concentrations of the order of 1 ppm of fragrance vapors in air could be determined [24,30]. Lu's group successfully developed a CTL n-hexane sensor using zeolite based on the well-known photocatalyzed oxidation of hydrocarbons being able to occur in zeolite cages [37]. Our group proposed a Y-doped metal-organic framework (MOF)-based CTL gas sensor [42] for isobutanol using MOFs with variable topology structure and excellent gas adsorption and catalytic properties [43].…”

Sensitive and selective acetone sensor based on its cataluminescence from nano-La2O3 surface

“…For example, Nakagawa et al [12][13][14][15] and Zhang et al [16][17][18][19][20][21] have made persistent efforts for exploration of CTL phenomena on nanoparticles or nanoporous materials, such as ␥-Al 2 O 3 , V 2 Ti 4 O 13 , BaCO 3 , Fe 2 O 3 , TiO 2 , SrCO 3 , and ZnO, and established many sensitive and selective sensors for the determination of VOCs, including formaldehyde [16], acetaldehyde [17], hydrogen sulfide [18], chlorinated volatile organic compounds [19] and alcohols [20][21][22]. It is worth mentioning here that Lu et al also developed CTL sensors based on zeolite [23] for n-hexane and Al 2 O 3 [24] for acetone. Coupled with a headspace solid-phase microextraction (HS-SPME) pretreatment, the latter provided a simple, rapid, solvent-free, and sensitive methodology for the determination of acetone in blood.…”

Assembly of Nanostructures for Taste Sensing

“…The proposed ethyl ether gas sensor offered the following distinct advantages: (1) Compared with GC and GC/MS, it is a simple and cost-effective sensor; (2) it is a greener sensor, since no toxic reagent/solvent is needed, and the exhaust is of low toxicity and at low concentrations; and (3) it shows much better sensitivity and selectivity, and faster response than many common VOC sensors. Yang et al described the development of a novel CTL sensor coupled with ionic liquids (ILs)-based headspace solid-phase microextraction (HS-SPME) technologies for the quantification of human plasma acetone levels associated with diabetic disease ex vivo [27]. The unique properties of ILs, such as their nonvolatile and nonflammable nature, coupled with their high thermal stability allowed ILs to be conveniently adopted as pseudo-solid carriers for direct loading of acetone into a CTL sensor without matrix interference.…”