Studies of the cataluminescence of benzene homologues on nanosized γ-Al2O3/Eu2O3 and the development of a gas sensor for benzene homologue vapors

The cataluminescence (CTL) of benzene and the benzene homologues toluene and xylene on nanosized gamma-Al2O3 doped with Eu2O3 (gamma-Al2O3/Eu2O3) was studied and a sensor of determining these gases was designed. The proposed sensor showed high sensitivity and selectivity at an optimal temperature of 432 degrees C, a wavelength of 425 nm and a flow rate of 400 mL/min. Quantitative analysis was performed at the optimal conditions. The linear ranges of CTL intensity versus concentration of the benzene homologues were as follows: benzene 2.4 similar to 5000 mL/m(3), toluene 4.0 similar to 5000 mL/m(3) and xylene 6.8 similar to 5000 mL/m(3), with detection limits (3 sigma) of 1.8 mL/m(3), 3.0 mL/m(3) and 3.4 mL/m(3) for each one, respectively. The response time of this system was less than 3 s. The coexistence of other gases, such as SO2, CO and NH3, caused interference at levels around 11.7%, 5.8% and 8.9% respectively. The technique is a convenient and fast way of determining the vapors of benzene homologues in air.