Досліджено каталітичну активність нанорозмірних сенсорних матеріалів Pd/SnO2 в реакції окиснення метану та встановлено її вплив на формування чутливості адсорбційно-напівпровідникових сенсорів до 937 ppm метану у повітрі. Показано, що в умовах надлишку кисню порядок реакції окиснення метану за киснем є нульовим, а за метаном - першим.
Исследована каталитическая активность наноразмерных сенсорных материалов Pd/SnO2 в реакции окисления метана и установлено её влияние на формирование чувствительности адсорбционно-полупроводниковых сенсоров к 937 ppm метана в воздухе. Показано, что в условиях избытка кислорода порядок реакции окисления метана по кислороду нулевой, а по метану - первый.
Nanosized initial tin dioxide for sensors has been synthesized by sol-gel technique. Nanosized Pd/SnO2 sensor materials with average particles sizes 14-15 nm have been prepared by wet impregnation method. For the sensor material without palladium an average particle size was approximately 20 nm. Catalytic activities of the Pd/SnO2 materials in a methane oxidation reaction have been studied and their influence on formation of corresponding adsorption semiconductor sensor responses to 937 ppm of CH4 has been investigated. It was shown that the catalytic activities of t&he samples increase with increasing of loaded palladium content. Dependences of the sensor responses on palladium content have an extreme characters with maximum for the sensors based on the material containing 1.41 wt. % of Pd. It could be attribute&d to a role of an interface between palladium clusters and tin dioxide. The interface consists of defects that can chemisorb oxygen from the air. A quantity of such defects depends on the length of the interface - a longer interface consists of a lar&ger amount of the defects. Thus the influence of the interface length on values of electrical resistances of the sensors in air should be significant. Indeed the sensor based on 1.41wt. % Pd/SnO2 material has the highest value of the electrical resis&tance in air owing to its longest interface. The sensors with the longest interfaces can chemisorb more oxygen quantity. As a result, rates of methane oxidation reaction on surfaces of such sensors will be higher because methane activated on the pall&adium clusters could be oxidized by oxygen chemisorbed on the interface. Therefore, the sensors with higher values of the electrical resistances should demonstrate greater sensor responses. This assumption is in agreement with experimental data. Kine&tic of the methane oxidation reaction has been also investigated in excess of oxygen for the sensor material 1.41wt. % Pd/SnO2 with the highest sensor response. The first order for methane and zero order for oxygen were occurred for the reaction. A v&alue of activation energy of the reaction is 78±4 kJ/mol that is in agreement with literature data.
