Researchers from the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory and its collaborating institutions have developed an extremely efficient catalyst that can transform methane, a primary element of natural gas, into methanol, a liquid fuel that’s easy to transport, all in a straightforward, single-step process. According to a recently published study in the Journal of the American Chemical Society, this innovative method for converting methane to methanol operates at a temperature lower than that needed to brew tea, solely producing methanol without generating any extra byproducts.
This represents a significant improvement over traditional conversion methods, which are typically more complicated and require three separate reactions, each with varying conditions and notably higher temperatures.
“We essentially place everything in a pressure cooker, and the reaction occurs on its own,” stated chemical engineer Juan Jimenez, a Goldhaber postdoctoral fellow in Brookhaven Lab’s Chemistry Division and the primary author of the paper.
The straightforward nature of this system could be especially beneficial for accessing “stranded” natural gas reserves found in remote rural areas, where costly pipelines and chemical refineries are absent, noted Brookhaven chemist and co-author of the study, Sanjaya Senanayake. Implementing this approach locally would eliminate the need to transport liquified natural gas, which is both high-pressure and flammable.
“We could scale this technology up and deploy it in local areas to produce methanol for fuel, electricity, and chemical manufacturing,” Senanayake added.
Brookhaven Science Associates, which oversees Brookhaven Lab for the DOE, along with the University of Udine, partners in this research, have submitted a patent cooperation treaty application regarding the catalyst’s one-step methane conversion process. The team is currently exploring partnerships with entrepreneurs to commercialize the technology. Their aim is centered on the idea of “closing the carbon cycle,” which refers to recycling carbon to avoid its release into the atmosphere, thus facilitating net-zero carbon clean energy solutions.
“As scientists, we possess a profound understanding of the science and technology involved, but we collaborate with Brookhaven’s Research Partnerships and Technology Transfer Office and entrepreneurial students who are responsible for the economic aspects — identifying the most suitable potential clients and markets for expansion,” Jimenez mentioned.
From basic science to industry-ready
The foundational science behind this conversion stems from a decade of joint research. The chemists at Brookhaven collaborated with specialists from the Lab’s National Synchrotron Light Source II (NSLS-II) and Center for Functional Nanomaterials (CFN) — two user facilities from the DOE Office of Science that offer a range of capabilities to analyze the details of chemical reactions and the catalysts that facilitate them — along with scientists at DOE’s Ames National Laboratory and international colleagues in Italy and Spain.
Previous investigations dealt with simplified ideal models of the catalyst, consisting of metal layered over oxide supports or inverted oxide on metal materials. The team utilized computational modeling and various techniques at NSLS-II and CFN to comprehend how these catalysts function in breaking and reforming chemical bonds to convert methane to methanol and to clarify the role of water in the process.
“Those earlier investigations were conducted on simplified model catalysts in very controlled environments,” Jimenez remarked. These studies provided valuable insights into the molecular characteristics of the catalysts and the potential progression of the reaction, “but they needed to be adapted to reflect what a real-world catalytic material resembles,” he explained.
As Senanayake noted, “What Juan has accomplished is taking those concepts we learned from the reaction and refining them, collaborating with our materials synthesis team at the University of Udine in Italy, theorists from the Institute of Catalysis and Petrochemistry, and Valencia Polytechnic University in Spain, along with characterization specialists here at Brookhaven and Ames Lab. This new work validates the principles derived from earlier studies and translates lab-scale catalyst synthesis into a more practical method for producing kilogram-scale quantities of catalytic powder that are directly relevant for industrial use.”
New tools uncover the secret sauce
The updated catalyst formulation includes an extra component: a thin interfacial layer of carbon situated between the metal and oxide.
“Carbon is frequently overlooked as a catalyst,” Jimenez explained. “However, our extensive experimental and theoretical investigations demonstrated that a fine layer of carbon between palladium and cerium oxide was crucial to the chemistry. This layer was essentially the secret ingredient that enables palladium to effectively convert methane into methanol.”
To delve into this unique chemistry, the researchers established new research facilities both within the Catalysis Reactivity and Structure group’s lab in the Chemistry Division and at NSLS-II.
“This reaction involves three phases — gas, solid, and liquid components; specifically, methane gas, hydrogen peroxide and water as liquids, and the solid powder catalyst — all reacting under pressure. Thus, we had to develop new pressurized three-phase reactors that would allow us to monitor these ingredients in real-time,” Senanayake elaborated.
The team constructed one reactor in the Chemistry Division and employed infrared spectroscopy to evaluate reaction rates and to identify the chemicals produced on the catalyst’s surface as the reaction progressed. Additionally, chemists utilized expertise from NSLS-II scientists who designed and built further reactors to be installed at two of the NSLS-II beamlines — Inner-Shell Spectroscopy (ISS) and In situ and Operando Soft X-ray Spectroscopy (IOS) — enabling them to also examine the reaction using X-ray methods.
Dominik Wierzbicki, a co-author of the study at NSLS-II, played a crucial role in designing the ISS reactor to observe the high-pressure, gas-solid-liquid reaction through X-ray spectroscopy. This technique employed “hard” X-rays, characterized by relatively high energies, allowing researchers to monitor the active palladium metal under realistic reaction conditions.
“Usually, this technique involves trade-offs due to the complexity of measuring the gas-liquid-solid interface, and high-pressure conditions complicate matters further,” Wierzbicki noted. “Enhancing the unique capabilities at NSLS-II to tackle these challenges is enriching our mechanistic comprehension of high-pressure reactions and paving the way for novel synchrotron research opportunities.”
Co-authors Iradwikanari Waluyo and Adrian Hunt, beamline scientists at IOS, also developed an in-situ setup within their beamline, utilizing it for low-energy “soft” X-ray spectroscopy to investigate cerium oxide at the gas-solid-liquid interface. These experiments provided insights into the nature of the active catalytic species under simulated reaction scenarios.
“Synchronizing the findings from the Chemistry Division with the two beamlines required collaboration, which is central to our new capabilities,” Senanayake commented. “This joint effort has provided distinctive insights into how the reaction can take place,” he added, describing this study as a pioneering demonstration of how such collaboration can yield new knowledge.
Multimodal characterization tools enhance scientists’ knowledge of catalytic reactions that occur under high pressure.
Waluyo mentioned, “The tools we’ve created for this study now offer improved in situ capabilities for other NSLS-II users who want to explore chemistry under pressure at our beamlines.”
Additionally, scientists Jie Zhang and Long Qi from Ames Lab conducted in situ nuclear magnetic resonance studies, which provided essential insights into the initial phases of the reaction. Meanwhile, Sooyeon Hwang at CFN generated impressive transmission electron microscopy images to detect carbon within the material. The theoretical team from Spain, led by Verónica Ganduglia-Pirovano and Pablo Lustemberg, formulated a cutting-edge computational model to explain the catalytic mechanism behind the three-phase reaction.
Senanayake remarked, “We collaborated with a worldwide team to achieve a thorough understanding of the reaction and its mechanism.”
Ultimately, the team unveiled how the active state of their three-component catalyst — composed of palladium, cerium oxide, and carbon — utilizes the intricate three-phase microenvironment of liquid, solid, and gas to yield the target product.
Now, instead of relying on three different reactions in separate reactors with varying conditions to convert methane into methanol and facing the challenge of byproducts that necessitate expensive separation processes, the team has developed a three-component catalyst that facilitates a three-phase reaction within a single reactor, achieving 100% selectivity for methanol production.
Senanayake added, “This serves as a significant example of carbon-neutral processing. We are excited to see this technology implemented on a large scale to harness currently unused sources of methane.”
John Gordon, chair of the Chemistry Division, expressed, “This research demonstrates how advances in catalyst design and a fundamental understanding of reaction mechanisms can propel the advancement of future chemical processes.”
The research conducted at Brookhaven National Laboratory received support from the DOE Office of Science and a Brookhaven National Laboratory Goldhaber Distinguished Fellowship. The study also benefited from collaboration and supercomputing resources backed by other funding sources, including international organizations outlined in the research paper. Furthermore, NSLS-II and CFN operations at Brookhaven are funded by the Office of Science.
