Scientists will develop an effective sensor for detecting hydrogen leaks

(ORDO NEWS) — Hydrogen is the fuel with the highest thermal conductivity among gaseous substances, and a more environmentally friendly alternative to the traditional one – when it is burned, only water is formed.

Since the whole world is focused on the transition to environmentally friendly types of energy, in the near future hydrogen may become the main type of fuel in energy, industry and transport, gradually replacing coal, fuel oil, diesel fuel, gasoline and natural gas.

Despite all its attractiveness, hydrogen is extremely dangerous: its flammability limit in a gas-air mixture is much wider than that of hydrocarbons. Therefore, to prevent emergency situations associated with its leakage, the detection of hydrogen in the air is an urgent task.

It is on this problem that MAI is working. The project to develop a selective thermal catalytic hydrogen sensor became the winner of the 2021 competition for grants from the Russian Science Foundation in the direction of “Conducting fundamental scientific research and exploratory scientific research by small individual scientific groups.”

A group of graduate students, employees and graduates of the Department of Radioelectronics, Telecommunications and Nanotechnologies of Institute No. 12 Aerospace Science-Intensive Technologies and Production of the Moscow Aviation Institute, headed by Professor Alexander Baranov, is working on the project.

Great interest in the study was shown by the Scientific and Technical Center for Measuring Gas-Sensing Sensors named after V.I. E.F. Karpov, which has the technological facilities for the production of thermal catalytic sensors, as well as analytical equipment for the study of their parameters and characteristics.

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Why thermal catalytic?

From the point of view of preventing explosive situations, the most relevant measurement range for hydrogen in air is from 0.1 vol. %. (lower limit of hydrogen detection established in different countries) up to 2 vol. % (50% of the lower concentration limit of flame propagation).

For this range, it is optimal to use thermal catalytic sensors. Their additional advantages, in comparison with others, are low cost, small size and weight.

Despite the fact that catalytic thermal sensors have been developed for many decades, the same sensors are used for measuring hydrogen as for combustible gases and vapors.

Since hydrogen and hydrocarbons have too different properties, including combustion temperature, fluidity and explosiveness, the goal of the work of the team of scientists was to adapt thermal catalytic sensors to improve parameters when measuring hydrogen (sensitivity, response time, operating voltage, and others).

Why selective?

The selectivity of a sensor is its ability to respond to only one substance in a mixture of gases. This is done using a catalyst. Therefore, the task of specialists is to create a catalyst that will enable the sensor to sense hydrogen, but will not react to other gases.

The operating temperature for working with hydrogen is 300-400 degrees. The strategic goal of the project is to carry out selective measurements of hydrogen in air or in mixtures with other combustible gases at temperatures close to room temperature.

This will make it possible to increase the safety of work (reduce the level of explosion hazard) and reduce power consumption – increase the battery life.

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Platinum group metals act as catalysts in gas sensors, but not all of them have previously been used for hydrogen monitoring. The novelty of the work lies in the use of catalysts iridium (Ir) and rhodium (Rh) in its pure form, form or mixed with platinum (Pt) and palladium (Pd).

Research on various platinum group catalysts is being conducted to improve the parameters and performance of thermal catalytic sensors, such as selectivity, sensitivity, response time, sensor temperature, long-term stability, and power consumption.


As a result of optimizing the structure and composition of the catalyst of the thermal catalytic sensor, as well as changing the classical approach for measurements, it was possible to reduce the operating temperature of the thermal catalytic sensor to approximately 80 ºС, while traditionally, with similar measurements, the operating temperature of the thermal sensors above 250 ºС.

In this case, the lower limit of the temperature range is determined mainly by the sensitivity of the sensor. The next task is to check the long-term stability of the sensor.

“If the target gas is hydrogen, then there is no degradation of the sensor parameters over time, as happens when measuring other combustible and explosive gases.

In addition, a high temperature (400-450 ºС) is needed to measure hydrocarbons, which also accelerates the degradation of the catalyst ,” Alexander Baranov explains.


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