Thursday, January 01, 2026

21st CENTURY ALCHEMY

Sulfur isn’t poisonous when it synergistically acts with phosphine in olefins hydroformylation

Dalian Institute of Chemical Physics, Chinese Academy Sciences

Figure Abstract — image:
Researchers at the Dalian Institute of Chemical Physics have designed a rhodium catalyst whose microenvironment is tuned by both sulfur and phosphine ligands, based on an industrial single-site Rh1/POPs catalyst. The new “single-site” catalyst hydroformylates propylene and higher olefins up to twice as fast as the current benchmark, while maintaining high selectivity and stability. The study explains how a carefully controlled amount of sulfur can switch from poisoning the catalyst to promoting its performance.
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Credit: Chinese Journal of Catalysis

Dalian, China-Sulfur, long feared as a “poison” that shuts down precious metal catalysts, can actually help them work better when used in just the right way, according to new research published in Chinese Journal of Catalysis.

A team led by Prof. Yunjie Ding at Dalian Institute of Chemical Physics, Chinese Academy of Sciences andProf. Xueqing Gong at Shanghai Jiao Tong University, has shown that a tiny, carefully tuned amount of sulfur can boost the speed and robustness of a key industrial reaction by up to twofold.

The reaction, called hydroformylation, adds carbon monoxide and hydrogen to simple molecules known as olefins (alkenes) to make aldehydes. These aldehydes are essential building blocks for alcohols, plasticizers, surfactants, lubricants and many other bulk and specialty chemicals. Worldwide, more than 25 million tons of aldehydes and alcohols are made each year by hydroformylation, mostly using rhodium-based catalysts dissolved in liquid.

“Hydroformylation is one of the workhorses of modern chemical industry,” the authors note in the paper. “Designing catalysts that are both highly active and tolerant to real-world, sulfur-containing feedstocks is crucial for greener production.”

Traditionally, sulfur compounds in feed gases or liquids are seen as a serious problem. They bind very strongly to precious metals like rhodium, blocking the active sites and deactivating the catalyst. As a result, major effort is spent on deep desulfurization-removing sulfur as completely as possible before the reaction.

The new study takes a very different approach: instead of fighting sulfur at all costs, the researchers ask whether sulfur can be harnessed and controlled.

Tuning the catalyst’s “microenvironment”

The team builds on an earlier heterogeneous (“solid”) rhodium catalyst, known as Rh₁/POPs-PPh₃, in which isolated rhodium atoms are anchored to a porous organic polymer (POPs-PPh3) through frame-phosphine (frame-P) ligands. That system has already been demonstrated at industrial scale for hydroformylation.

In the new work, the researchers designed a related material where the porous polymer framework contains both phosphine and sulfur sites. When rhodium is introduced, each single rhodium center can be coordinated by a mixture of phosphorus and sulfur atoms, creating a sulfur–phosphine co-coordinated microenvironment (Rh₁/POPs-PPh₃&S).

By varying the ratio of sulfur to phosphine in the polymer, they discovered a “sweet spot”:

At about 10% sulfur in the framework, the new catalyst hydroformylates propylene and C₅–C₈ olefins 1.5–2.0 times faster than the phosphine-only benchmark,
while maintaining high selectivity to the desired linear aldehydes and showing excellent stability in long-term tests.

In contrast, when sulfur dominates the coordination, the catalyst indeed suffers severe sulfur poisoning and its performance drops sharply, confirming that dosage and microenvironment are critical.

Seeing how sulfur helps instead of “hurts”

To understand why a small amount of sulfur promotes rather than harms, the team combined advanced characterization and computer modelling.

Using high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and X-ray absorption spectroscopy, they confirmed that rhodium remains atomically dispersed — as single “mononuclear” centers — in both the original and the sulfur-modified catalysts. Solid-state NMR and X-ray photoelectron spectroscopy showed that adding sulfur partly replaces phosphine around rhodium slightly lowers the electron density on the metal.

In simple terms:

Phosphine ligands are strong electron donors. They tend to make rhodium more electron-rich and highly reactive.
Sulfur ligands are more electron-withdrawing and occupy one coordination site, which can moderate rhodium’s reactivity.

Using in-situ infrared spectroscopy under reaction conditions and temperature-programmed surface reaction experiments, the researchers observed that the sulfur–phosphine catalyst forms key aldehyde-forming intermediates faster, while suppressing unwanted hydrogenation and isomerization by-products.

Density functional theory (DFT) calculations then revealed that the rate-determining step in hydroformylation — the insertion of the olefin into a rhodium–hydrogen bond — has a lower energy barrier on the sulfur–phosphine co-coordinated catalyst than on the phosphine-only one. The calculations also showed how the combination of electron-donating phosphine and electron-withdrawing sulfur tunes the charge and bond lengths around rhodium into an optimal window for reactivity and selectivity.

Rethinking “sulfur poison” for real-world feedstocks

The work provides a unified picture of when sulfur behaves as a poison and when it can act as a promoter:

Too little sulfur, and the catalyst behaves like the original phosphine system.
Too much sulfur, and rhodium sites are blocked, leading to classic sulfur poisoning and poor performance.
At an intermediate sulfur level, the microenvironment around single rhodium atoms is ideally tuned, giving higher activity, better regioselectivity and robust stability.

This insight could be particularly important for processing sulfur-containing feedstocks, such as coal-based chemicals, biomass-derived oils, or low-grade olefin streams, where completely removing sulfur is costly or impractical.

“Our results suggest that, instead of treating sulfur as an absolute enemy, we can sometimes design catalysts that tolerate and even use sulfur to their advantage,” the authors write. The concept of microenvironment engineering around single-atom active sites may also be applied to other catalytic reactions beyond hydroformylation.

Article details

The research article, “Regulating microenvironment of heterogeneous Rh mononuclear complex via sulfur-phosphine co-coordination to enhance the performance of hydroformylation of olefins,” by Siquan Feng, Cunyao Li, Yuxuan Zhou, Xiangen Song, Yunjie Ding and co-workers, appears in Chinese Journal of Catalysis (Vol. 78, 2025, pp. 156–169).
DOI: 10.1016/S1872-2067(25)64795-4

Corresponding authors:

Prof. Yunjie Ding, Dalian Institute of Chemical Physics, Chinese Academy of Sciences
Email: dyj@dicp.ac.cn

About the Journal

Chinese Journal of Catalysis is co-sponsored by Dalian Institute of Chemical Physics, Chinese Academy of Sciences and Chinese Chemical Society, and it is currently published by Elsevier group. This monthly journal publishes in English timely contributions of original and rigorously reviewed manuscripts covering all areas of catalysis. The journal publishes Reviews, Accounts, Communications, Articles, Highlights, Perspectives, and Viewpoints of highly scientific values that help understanding and defining of new concepts in both fundamental issues and practical applications of catalysis. Chinese Journal of Catalysis ranks among the top one journals in Applied Chemistry with a current SCI impact factor of 17.7. The Editors-in-Chief are Profs. Can Li and Tao Zhang.

At Elsevier http://www.journals.elsevier.com/chinese-journal-of-catalysis

Manuscript submission https://mc03.manuscriptcentral.com/cjcatal

Journal

Chinese Journal of Catalysis

DOI

10.1016/S1872-2067(25)64795-4

Article Title

Regulating microenvironment of heterogeneous Rh mononuclear complex via sulfur-phosphine co-coordination to enhance the performance of hydroformylation of olefins

Turning PC and mobile devices into AI infrastructure, reducing ChatGPT costs

The Korea Advanced Institute of Science and Technology (KAIST)

Until now, AI services based on Large Language Models (LLMs) have mostly relied on expensive data center GPUs. This has resulted in high operational costs and created a significant barrier to entry for utilizing AI technology. A research team at KAIST has developed a technology that reduces reliance on expensive data center GPUs by utilizing affordable, everyday GPUs to provide AI services at a much lower cost.

On December 28th, KAIST announced that a research team led by Professor Dongsu Han from the School of Electrical Engineering developed 'SpecEdge,' a new technology that significantly lowers LLM infrastructure costs by utilizing affordable, consumer-grade GPUs widely available outside of data centers.

SpecEdge is a system where data center GPUs and "edge GPUs"—found in personal PCs or small servers—collaborate to form an LLM inference infrastructure. By applying this technology, the team successfully reduced the cost per token (the smallest unit of text generated by AI) by approximately 67.6% compared to methods using only data center GPUs.

To achieve this, the research team utilized a method called 'Speculative Decoding.' In this process, a small language model placed on the edge GPU quickly generates a high-probability token sequence (a series of words or word fragments). Then, the large-scale language model in the data center verifies this sequence in batches. During this process, the edge GPU continues to generate words without waiting for the server's response, simultaneously increasing LLM inference speed and infrastructure efficiency.

Compared to performing speculative decoding solely on data center GPUs, SpecEdge improved cost efficiency by 1.91 times and server throughput by 2.22 times. Notably, the technology was confirmed to work seamlessly even under standard internet speeds, meaning it can be immediately applied to real-world services without requiring a specialized network environment.

Furthermore, the server is designed to efficiently process verification requests from multiple edge GPUs, allowing it to handle more simultaneous requests without GPU idle time. This has realized an LLM serving infrastructure structure that utilizes data center resources more effectively.

This research presents a new possibility for distributing LLM computations—which were previously concentrated in data centers—to the edge, thereby reducing infrastructure costs and increasing accessibility. In the future, as this expands to various edge devices such as smartphones, personal computers, and Neural Processing Units (NPUs), high-quality AI services are expected to become available to a broader range of users.

Professor Dongsu Han, who led the research, stated, "Our goal is to utilize edge resources around the user, beyond the data center, as part of the LLM infrastructure. Through this, we aim to lower AI service costs and create an environment where anyone can utilize high-quality AI."

Dr. Jinwoo Park and M.S candidate Seunggeun Cho from KAIST participated in this study. The research results were presented as a 'Spotlight' (top 3.2% of papers, with a 24.52% acceptance rate) at the NeurIPS (Neural Information Processing Systems) conference, the world's most prestigious academic conference in the field of AI, held in San Diego from December 2nd to 7th.

Paper Title: SpecEdge: Scalable Edge-Assisted Serving Framework for Interactive LLMs
Paper Links: NeurIPS Link, arXiv Link

This research was supported by the Institute of Information & Communications Technology Planning & Evaluation (IITP) under the project 'Development of 6G System Technology to Support AI-Native Application Services.'

< Figure 4. Conceptual comparison of the developed SpecEdge vs. conventional methods >

< Figure 2. Detailed computation time reduction method of SpecEdge >

Credit

KAIST

DOI

10.48550/arXiv.2505.17052

Method of Research

Meta-analysis

Subject of Research

Not applicable

Article Title

SpecEdge: Scalable Edge-Assisted Serving Framework for Interactive LLMs

A Coral reef’s daily pulse reshapes microbes in surrounding waters

Peer-Reviewed Publication

The Hebrew University of Jerusalem

Dr. Herdís Steinsdóttir deploying an instrument near the reef in Eilat — image:
*Dr. Herdís* Steinsdóttir *deploying an instrument near the reef in Eilat to record water currents, allowing her to keep track of the direction of sea currents.*
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Credit: Photo credit: Jake Stout.

A new study shows that coral reefs don’t just provide a home for ocean life, they also help set the daily “schedule” for tiny microbes living in the water nearby. Over the course of a single day, the quantity and types of microbes present can shift dramatically. To see this in detail, researchers took frequent water samples and used a mix of genetic and ecological methods and tools, as well as advanced imaging techniques, to track what was happening hour by hour. They found that reefs can shape microbial communities through natural interactions like grazing and predation, as well as changes in the reef’s close microbial partners. These daily ups and downs offer a fresh window into how reefs work and influence the surrounding environment— and could even point to new ways to keep an eye on reef health.

Coral reefs are often described as biodiversity hotspots, but new research shows they also act as powerful regulators of the microscopic life in the surrounding ocean. A new study led by Dr. Herdís G. R. Steinsdóttir a postdoctoral researcher under the guidance of Dr. Miguel J. Frada of the Department of Ecology, Evolution and Behaviour at the Hebrew University of Jerusalem and the Interuniversity Institute for Marine Sciences in Eilat and Dr. Derya Akkaynak from the University of Haifa and the Interuniversity Institute for Marine Sciences in Eilat, reveals that coral reefs impose pronounced daily rhythms on nearby microbial communities, reshaping their composition and abundance over the course of a single day.

The study, published in Science Advances, tracked microbial populations in waters above a coral reef in the northern Gulf of Aqaba in the Red Sea, comparing them with nearby open waters across winter and summer seasons. Using high-frequency sampling every six hours, the researchers uncovered previously undocumented daily and seasonal cycles affecting bacteria, microalgae, and microscopic predators.

“We found that the reef is not just passively surrounded by microbes,” said Dr. Frada. “It actively structures microbial life in time, creating daily patterns that repeat across seasons and influence how energy and nutrients move through the ecosystem.”

The research team discovered that reef waters consistently contained significantly fewer bacteria and microalgae than adjacent open waters, suggesting active removal by reef organisms. At the same time, populations of heterotrophic protists, microscopic predators that feed on bacteria, increased sharply at night, sometimes by as much as 80 percent, suggesting predation as a major force shaping microbial dynamics.

One of the most striking findings involved Symbiodiniaceae, the family of dinoflagellates best known as coral symbionts. Genetic signatures of these organisms consistently peaked around midday in reef waters, pointing to daily cycles of release, growth, or turnover that may be linked to light conditions and coral metabolism.

“These daily microbial rhythms were as strong as, and sometimes stronger than, seasonal differences,” said Dr. Steinsdóttir. “This shows that time of day is a critical factor when studying reef-associated microbial communities.”

By combining genetic sequencing, flow cytometry, imaging technologies, and biogeochemical measurements, the interdisciplinary team provides one of the most detailed temporal views to date of microbial life around coral reefs. The findings suggest that microbial daily cycles could serve as sensitive indicators of reef functioning and ecosystem health in a changing ocean.

Dr. Herdís Steinsdóttir deploying an instrument near the reef in Eilat to record water currents, allowing her to keep track of the direction of sea currents.

Credit

Photo credit: Jake Stout.