#hydrogenation

Efficient indium oxide catalysts designed for CO2 hydrogenation to methanol

Catalytic hydrogenation of carbon dioxide (CO2) is a green and sustainable means of synthesizing commodity chemicals such as methanol. This conversion process is key to realizing the 'methanol economy' or creating 'liquid sunshine,' both aspects of the circular economy. Recent studies revealed the potential for a family of metal oxides to catalyze this reaction. However, further optimizing their catalytic performance for industrial applications remained a great challenge, mostly due to the difficulties related to the rational design and controlled synthesis of these catalysts.

Motivated by such a challenge, a team jointly led by Profs. Sun Yuhan, Gao Peng, and Li Shenggang at the Shanghai Advanced Research Institute (SARI) of the Chinese Academy of Sciences, reported a successful case of theory-guided rational design of indium oxide (In2O3) catalysts for CO2 hydrogenation to methanol with high activity and selectivity. The new findings were published in the latest issue of Science Advances on June 17.

To rationally design In2O3-based nanocatalysts with favorable methanol synthesis performance, researchers carried out extensive density functional theory (DFT) calculations to establish the catalytic mechanism of the In2O3 catalyst during CO2 hydrogenation to methanol and carbon dioxide by identifying preferred pathways. The computational modeling identified the rarely studied {104} facet of hexagonal In2O3 as the most favorable for methanol synthesis.

Diamond-based circuits can take the heat for advanced applications

Researchers have developed a hydrogenated diamond circuit operational at 300 degrees Celsius

When power generators like windmills and solar panels transfer electricity to homes, businesses and the power grid, they lose almost 10 percent of the generated power. To address this problem, scientists are researching new diamond semiconductor circuits to make power conversion systems more efficient.

A team of researchers from Japan successfully fabricated a key circuit in power conversion systems using hydrogenated diamond (H-diamond.) Furthermore, they demonstrated that it functions at temperatures as high as 300 degrees Celsius. These circuits can be used in diamond-based electronic devices that are smaller, lighter and more efficient than silicon-based devices. The researchers report their findings this week in Applied Physics Letters, from AIP Publishing.

Silicon's material properties make it a poor choice for circuits in high-power, high-temperature and high-frequency electronic devices. "For the high-power generators, diamond is more suitable for fabricating power conversion systems with a small size and low power loss," said Jiangwei Liu, a researcher at Japan's National Institute for Materials Science and a co-author on the paper.

Common 'oxygen sponge' catalyst soaks up hydrogen too, neutron spectroscopy reveals

Having the right tool for the job enabled scientists at the Department of Energy's Oak Ridge National Laboratory and their collaborators to discover that a workhorse catalyst of vehicle exhaust systems -- an "oxygen sponge" that can soak up oxygen from air and store it for later use in oxidation reactions -- may also be a "hydrogen sponge."

The finding, published in the Journal of the American Chemical Society, may pave the way for the design of more effective catalysts for selective hydrogenation reactions. Selective hydrogenation is the key to producing valuable chemicals, for example, turning triple-bonded hydrocarbons called alkynes selectively into double-bonded alkenes -- starting materials for the synthesis of plastics, fuels and other commercial products.

"Understanding how molecular hydrogen interacts with ceria [cerium oxide, CeO2], however, is a big challenge, as no regular technique can 'see' the light H atom. We turned to inelastic neutron spectroscopy, a technique that is very sensitive to hydrogen," said ORNL chemist Zili Wu. At ORNL's Spallation Neutron Source (SNS), a DOE Office of Science User Facility, a neutron beam line called VISION probed vibrational signals of atomic interactions and generated spectra describing them. "Because neutron spectroscopy could 'see' hydrogen due to its large neutron scattering cross-section, it succeeded where optical spectroscopy techniques failed and enabled the first direct observations of cerium hydrides both on the surface and in the bulk of a cerium oxide catalyst," Wu said.

Morphologies of porous molybdenum disulfide prepared by researchers show good performance in hydrogenation of phenol

Molybdenum disulfide (MoS2) is a transition metal chalcogenide material widely used in photocatalysis, synthesis catalyst, hydrodesulfurization, hydrodeoxygenation, electronic, optical, mechanical, even in hydrogen evolution reaction (HER). The morphology-controlled preparation of MoS2 is currently highly topical. Many preparation routes have been developed for synthesis of nanometer MoS2 over the last decades, and MoS2 nano-materials with different morphologies, particle sizes, and porous features can be obtained from different raw materials through different pathways. However, the morphology and crystal size of MoS2 was uncontrolled and the properties of the obtained material were variable.

The template method is an efficient means of synthesizing high specific surface area MoS2, and includes the soft template method and hard template method. Soft templates mainly include polymers and surfactants, MoS2 prepared through this method has no mesopores, a low surface area, and it is difficult to remove the template. Using hard templates to prepare MoS2 species have a wide pore size distribution. Based on the aforementioned considerations, Amino groups can coordinate well with molybdenum to assemble a long-range super-molecular system; it can prepare MoS2 nanoparticles with a high specific surface area, having a controllable pore size and continuous porous morphology.

A new method for the formation of fluorinated molecular rings

Dyes, pharmaceuticals, and functional materials are generally based on innovative molecules made by chemists. For their production, several chemical reactions are available, but there are limitations. For example, fluorinated compounds, molecules that contain at least one fluorine atom, are often difficult to prepare. This is unfortunate, since they exhibit interesting chemical properties and are of great importance for the development of active ingredients. Thus, researchers seek new techniques to produce these compounds.

Chemists from the Westfälische Wilhems-Universität (WWU) have developed a new and practical synthetic method for the formation of such fluorinated three-dimensional "saturated" (meaning only single-bond containing) molecular ring structures. The study has just been published online in the journal Science.

"I feel that our results are a breakthrough. It can have great importance for the efficient production of new molecules and, consequently, new drugs, crop protection agents and functional materials," says Frank Glorius.

His new synthetic method starts from flat, aromatic ring structures built up from carbon and bearing fluorine atoms. These starting materials include inexpensive, commercially available compounds and those that can be readily made.