A research led by ITQ (UPV-CSIC) has demonstrated the possibility to replace molecular catalysts in solution for all-solid catalysts based on isolated metal atoms for selective gas-phase ethylene hydroformylation, an important industrial chemical reaction. The discovery paves the way for greener chemical processes, with greater energy efficiency and lower carbon footprint, for the valorization of unconventional raw materials, alternative to crude oil. To test the designed catalyst, synchrotron light techniques have been used, among others, at the ALBA Synchrotron.
The hydroformylation of ethylene is a chemical process of remarkable industrial significance. In particular, this chemical reaction entails the net addition of a formyl group (-CHO carbon, hydrogen and oxygen) and a hydrogen atom to the ethylene carbon-carbon double bond. This process enables valorizing raw materials such as refinery off-gases as well as unconventional feedstocks such as shale-gas (a kind of natural gas) into oxygenated platform chemicals. Moreover, hydroformylation is also considered a reactive separation alternative to current cryogenic distillations, which are applied to recover ethylene, a valuable commodity chemical, from mixtures with less valuable gases such as ethane. Such cryogenic distillation separations count among the most energy demanding operations in the chemical industry and are therefore associated to high carbon footprints.
Catalysts are materials that are central to steering essentially all chemical transformations of the current chemical industry. A major class of industrially applied catalysts consists of molecular organometallic compounds that operate in a liquid solvent. These catalysts have proven to be highly active and exceedingly selective for a wide range of important transformations. However, they also face significant challenges. First, their limited thermal and chemical stability, which shortens their functional lifetime. On the other hand, the technical complexity associated with their recovery from liquid mixtures with products and solvents of the process, to prevent losses of the precious metals these catalysts are typically made of.
Now, scientists from the Instituto de Tecnología Química (ITQ, UPV-CSIC), the ALBA Synchrotron, the Institute for Nanoscience & Materials of Aragón (INMA, CSIC-UZ) and the Karlsruhe Institute for Technology have designed a new catalyst for selective gas-phase ethylene hydroformylation. Their research shows that a material bearing isolated atoms of rhodium (Rh) stabilized within the surface of stannic oxide (SnO2) is an all-inorganic solid catalyst which delivers an exceptional performance for the gas-phase hydroformylation of ethylene, in par with those thus far exclusive for conventional molecular catalysts in liquid media.
Read more on the ALBA website
Image: From left to right: Giovanni Agostini (former beamline responsible at NOTOS, ALBA), Gonzalo Prieto (ITQ), Juan José Cortés (ITQ), Wilson Henao (ITQ), Carlos Escudero (beamline scientist at NOTOS, ALBA) and Carlo Marini (beamline responsible of NOTOS, ALBA).