Towards luminescent temperature sensing in catalytic environments by exploiting Y2O3:Ln3+ / α-Al2O3 complexes
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Temperature is an important parameter in catalysis since it is related to the yield, selectivity and reaction speed of chemical conversions. Currently, it is not feasible to determine the temperature of industrial reactors in situ with a high spatial and thermal resolution. This is a major drawback for the control and optimization of the temperature in reactors. Here, we report the synthesis of Y2O3:Ln NPs (Ln = Eu3+, Dy3+ or Er3+/Yb3+) / α-Al2O3 temperature probes for in situ temperature determination in catalytic reactors with a high spatial and thermal resolution. Y2O3:Ln NPs synthesized by homogenous precipitation are between 50 and 250 nm in size and were deposited on the α-Al2O3 support material. Thermal and mechanical stability experiments confirmed firm adhesion of the NPs on α-Al2O3 and thermal stability of the complexes up to 600 ºC. Temperature dependent emission was observed for Eu3+- and Er3+/Yb3+-doped complexes for the temperature regions of 225-600 ºC and 22-500 ºC with accuracies higher than 14 and 3 ºC, respectively. Although the Dy3+-doped complexes exhibited temperature dependent luminescence, the signal to noise ratio was unsufficient for temperature determination. Thermal cycling experiments up to 600 ºC confirmed the preservation of luminescence after multiple cycles. Further research is required to study the temperature probes under industrially relevant conditions.