White Paper: Sensors/Data Acquisition
ATEX-Certified QCL Sensor Advances Petrochemical Safety and Efficiency with Ultra-Sensitive Sulfur Detection
SPONSORED BY: ![]()
Triple-QCL design, powered by Wavelength Electronics QCL drivers, delivers reliable, real-time, and simultaneous monitoring of multiple trace sulfur species in hazardous industrial environments.
Petrochemical processes remain central to today’s energy and manufacturing sectors, even as the global transition toward cleaner technologies accelerates. A persistent challenge in these processes is the presence of sulfur-containing compounds such as hydrogen sulfide (H₂S), methyl mercaptan (CH₃SH), and carbonyl sulfide (COS). Even at trace concentrations, these gases corrode equipment, poison catalysts, and pose serious safety and environmental risks. Reliable detection at extremely low levels is essential for efficiency, compliance, and safe operation.
Researchers at the Institute of Chemical Technologies and Analytics in Vienna, Austria, developed an ATEX-certified sensor specifically designed to address this challenge. The system integrates three distributed-feedback quantum cascade lasers (QCLs), each tuned to the absorption feature of one sulfur species. Using wavelength modulation spectroscopy (WMS) with second-harmonic detection, the sensor achieves exceptional sensitivity. Laboratory testing with a multi-pass Herriott cell demonstrated detection limits of 0.3 ppmv for H₂S, 60 ppbv for CH₃SH, and 5 ppbv for COS, with noise-equivalent absorption sensitivities in the 10⁻⁹ to 10⁻¹⁰ cm⁻¹·Hz-1/2 range. Field trials at a hydrodesulfurization (HDS) unit confirm consistent, real-time monitoring under dynamic process conditions.
To achieve such precise performance, the team relied on Wavelength Electronics’ QCL OEM Series drivers, which supplied ultra-stable, low-noise current to each laser. Stable current delivery is critical for maintaining wavelength precision and achieving ppbv-level detection. Compact driver design also supported the development of a field-deployable system without compromising safety or performance.
By combining robust industrial design, advanced spectroscopy, and reliable laser drive electronics, this project delivered a compact, high-performance sensor that meets the rigorous demands of dangerous petrochemical environments. The result is a practical solution that supports safer operations, minimizes downtime, and advances sustainable energy production.
Don't have an account?
Overview
The document presents a case study on an advanced sensor developed for the simultaneous detection of three sulfur-containing compounds—hydrogen sulfide (H₂S), methyl mercaptan (CH₃SH), and carbonyl sulfide (COS)—in petrochemical process streams. Researchers from the Institute of Chemical Technologies and Analytics in Vienna, Austria, designed this ATEX-certified sensor to address significant limitations faced by traditional monitoring methods, such as electrochemical sensors and gas chromatography, which often lack the sensitivity and selectivity required for detecting trace concentrations of these gases in complex mixtures.
The sensor utilizes quantum cascade lasers (QCLs) operating in the mid-infrared range, which allows for highly selective and ultra-sensitive detection of the target compounds. Each QCL is specifically tuned to the absorption band of a single sulfur species, ensuring full spectral coverage and minimizing cross-interference. The system integrates three distributed-feedback (DFB) QCLs, enabling real-time monitoring and accurate measurement of sulfur emissions, which is crucial for maintaining operational efficiency and environmental compliance in the petrochemical industry.
Field deployment of the sensor in an industrial hydrodesulfurization (HDS) unit demonstrated its reliability under dynamic process conditions. The sensor was able to deliver simultaneous, real-time data on sulfur species concentrations, with limits of detection (LOD) calculated at 0.3 ppmv for H₂S, 60 ppbv for CH₃SH, and 5 ppbv for COS. The design incorporates advanced spectroscopic techniques, including wavelength modulation spectroscopy (WMS) with second-harmonic detection, enhancing sensitivity and reducing background noise.
Safety was a primary concern in the sensor's design, ensuring compliance with ATEX certification standards for operation in potentially explosive environments. The enclosure is pressurized and continuously monitored to prevent the ingress of flammable gases, and critical safety electronics are integrated to isolate components in hazardous conditions.
The document highlights the role of Wavelength Electronics' QCL OEM Series drivers, which provide stable, low-noise current essential for maintaining precise wavelength and power output. This collaboration between researchers and manufacturers illustrates the successful execution of complex projects aimed at improving safety and sustainability in energy production.
Overall, the case study emphasizes the importance of innovative technologies like QCLs in enhancing the monitoring capabilities of sulfur emissions in the petrochemical industry, supporting both operational performance and environmental stewardship.