Researchers at King Fahd University of Petroleum and Minerals in Saudi Arabia have developed an inexpensive nickel‑based catalyst for the dry reforming of ethane, which could replace costly alternatives. The new material enables efficient conversion of carbon dioxide and ethane into synthesis gas, a mixture of hydrogen and carbon monoxide, widely used in the chemical industry.
The dry reforming of ethane is a well‑known process: at high temperatures, ethane and carbon dioxide react to produce hydrogen and carbon monoxide. The resulting synthesis gas is used to produce synthetic fuels, methanol, and other chemical products. Ethane is the second most abundant component of natural gas. Compared to methane, which is more commonly used in similar processes, ethane molecules react more readily, so reforming can be carried out at lower temperatures, specifically approximately 500‑650 °C instead of 750‑800 °C. This reduces energy consumption. However, one of the main challenges remains, precisely, selecting a catalyst that effectively activates both ethane and CO₂, does not become covered with carbon deposits, and maintains activity over a long period.
To identify the most suitable option, the authors prepared a series of catalysts based on cerium oxide with the addition of various metals such as rhodium, nickel, iron, tungsten, and zirconium. They subsequently studied the structure and properties of the resulting materials using X‑ray diffraction, electron microscopy, and temperature‑programmed reduction and desorption methods. This allowed them to determine which catalyst properties ensure high reaction efficiency and help maintain performance over time. All materials were then tested under identical conditions, comparing ethane and CO₂ conversion rates, product composition, and resistance to coke formation.
The highest activity was shown by the catalyst containing 2% rhodium. At 650 °C, it achieved conversion of nearly 99% of ethane and about 77% of carbon dioxide. However, rhodium is an expensive precious metal, and its use resulted in about 12‑15% of products being undesirable methane. A more practical option proved to be the catalyst with 15% nickel. At the same temperature, it converted about 86% of ethane and 74% of CO₂. Methane and ethylene accounted for less than 1% of products, with the remainder being hydrogen and carbon monoxide. Since nickel is significantly cheaper than rhodium, this material is more attractive for potential industrial application.
The study also showed that the efficiency of the nickel catalyst depends not only on its composition but also on the ratio of feed gases. When CO₂ and ethane were supplied in equal amounts, the catalyst quickly became covered with carbon deposits and lost almost all activity within six hours. With a three‑fold excess of carbon dioxide, it operated for 48 hours: ethane conversion gradually decreased from about 80% to 52%, and CO₂ conversion from 70% to 48%, but hydrogen and carbon monoxide remained the main products. The excess CO₂ helped remove part of the carbon from the surface and slowed catalyst deactivation.
The proposed technology could potentially be used at gas processing and petrochemical plants to produce synthesis gas from ethane and CO₂.
