Styrene, the chemical used to make the polymers and resins used in plastics, disposable containers, latex, synthetic rubber, insulation and more, is ubiquitous in everyday life.
Given its prevalence and importance, an inexpensive, energy-efficient and environmentally sustainable production method is essential. The traditional – and currently most common – method of producing ethylbenzene by dehydrogenation, however, has drawbacks in these areas: it requires an excess of superheated steam or results in a lack of precise control of the uniformity of the structure of the catalysts.
Now, a team of researchers led by Hongyang Liu from the Metals Research Institute of the Chinese Academy of Sciences has developed a method for dehydrogenating ethylbenzene under oxygen-free conditions with platinum cluster catalysts. (Pt) fully exposed which results in positive traits of high activity, selectivity and stability, as well as lower energy and financial costs. The results will be published on July 10 in Nano-research.
“We prepared fully exposed Pt cluster catalysts by exploiting the carbon defects on the surface of the graphene support and the physical segregation of atomically dispersed tin (Sn),” said Liu, who is also named at the University of Science and Technology of China. . “Fully exposed Pt clusters can promote desorption of the target product, styrene, giving it greater dehydrogenation activity and stability than Pt nanoparticle catalysts.”
In contrast, a common previous method of ethylbenzene dehydrogenation took place over iron oxide catalysts, required high temperatures resulting in carbon deposition, and required excess superheated steam. To overcome this, the researchers used single atom catalysts (SAC) and fully exposed cluster catalysts (FECCS).
“SACs and FECCs offer a wide atomic dispersion range and full metal utilization efficiency, which can provide enhanced activity and have attracted a lot of interest,” Liu said. “In particular, the active sites of FECCs generally contain various combinations of multiple metal atoms and are suitable for the catalysis of reagents requiring assembly metal sites.”
However, SACs and FECCs have their own limitations, including imprecise control of the uniformity of the structure of FECCs and the aggregation of metal atoms into metal clusters or nanoparticles caused by their high surface energy and thermodynamic instability when they are exposed to high temperatures.
While other researchers have sought to design high-activity, high-stability FECCs suitable for high-temperature reactions such as the dehydrogenation of ethylbenzene, as this team of researchers did, previous studies used oxides of non-precious metals or carbonaceous materials for catalysts, which require high energy. and water consumption and result in low activity. Energy consumption can be solved by oxidation of the process, but this leads to poor selectivity and risks with flammable mixtures.
“In our research, we used fully exposed nanodiamond/graphene-based Pt cluster catalysts decorated with atomically dispersed Sn for the dehydrogenation of ethylbenzene under oxygen-free conditions, which exhibited high activity, selectivity and stability. higher compared to previous catalysts, opening a new path for designing stable atomically dispersed metal catalysts,” Liu said. “We have achieved good catalytic performance in the dehydrogenation of alkanes.”
Another part of the appeal of this method, according to the researchers, is its ability to adapt to other types of catalysts.
“The ruthenium, rhodium and iridium catalysts were prepared by the same preparation method, and all showed good catalytic performance in the direct dehydrogenation of ethylbenzene, indicating that the proposed efficient catalyst design method in this article is universal,” Liu said. “The catalyst design method provides a new insight for designing efficient dehydrogenation catalysts of atomically dispersed metal alkane.”
The researchers say that they will continue to develop the design methods and applications of atomic dispersion metal catalysts in this research, including multi-metals, various reactions, practical applications, etc.
High Load Atomic Dispersion Ir/MoC Catalyst for Hydrogenation Reaction
Linlin Wang et al, Fully exposed Pt clusters stabilized on an Sn-decorated nanodiamond/graphene hybrid support for efficient direct dehydrogenation of ethylbenzene, Nano-research (2022). DOI: 10.1007/s12274-022-4650-6
Provided by Tsinghua University Press
Quote: New Styrene Production Method Improves Stability, Dehydrogenation Activity (July 7, 2022) Retrieved July 8, 2022 from https://phys.org/news/2022-07-styrene-production-method-stability- dehydrogenation.html
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