(521bp) Tandem Catalytic CO2-Assisted Propane Dehydrogenation and Propylene Hydroformylation for Production of Butanal

To reduce society’s reliance on fossil fuels, the development of alternative, sustainable pathways for producing carbon-neutral liquid fuels and valuable chemicals have been of increasing importance in recent years. Carbon capture and utilization (CCU) technology, which involves utilising CO2 emissions as a carbon resource to produce important chemical products, represents an integral component of carbon mitigation and decarbonisation strategies.

Hydroformylation is a chemical process of great industrial significance. This is mainly centred around producing n-butanal, a key precursor to pharmaceutical chemicals, plasticizers and alternative fuels (butanol). CO2-assisted propane dehydrogenation has emerged as a key topic in recent sustainability-focused research efforts. Utilisation of CO2 as a mild oxidant has been shown to provide significant thermodynamic and stability advantages to the energy-intensive dehydrogenation process. Due to the presence of the reverse water-gas shift pathway in this reaction, it was postulated that direct conversion from the alkane to the target aldehyde is possible, using CO2 as the carbon source and to gain significant performance advantages due to equilibrium and oxidative effects. Accordingly, this study was conducted to develop a novel catalyst and reactor system for the tandem catalysis of CO2-assisted propane dehydrogenation and propylene hydroformylation to produce butanal (Fig 1).

The thermodynamic study conducted with ASPEN Plus provided significant insight into the favourable pathways and optimal operating conditions in this envisioned tandem reaction system. Employment of a multi-temperature zone furnace facilitated catalytic testing with multiple catalytic beds at a temperature gradient in a modular reactor tube. Catalytic performance was determined from the product compositions obtained during catalytic runs. Catalyst characterisation with X-ray powder diffraction (XRD), Brunauer-Emmett-Teller (BET) analysis and temperature-programmed desorption provided crucial insights into catalytic behaviour.