Novel heterogeneous Rh-incorporated graphitic-carbon nitride for liquid-phase carbonylation of methanol to acetic acid

A novel heterogeneous rhodium-incorporated graphitic carbon nitride (Rh-g-C₃N₄) was investigated for a liquid-phase carbonylation of methanol to acetic acid (AA) to overcome disadvantages of the commercialized Rh-based homogeneous catalysts. The heterogeneous Rh-g-C₃N₄ catalyst showed a superior catalytic activity in a liquid-phase carbonylation with AA yield above 82% under the reaction conditions of 413 K and CO pressure of 4.0 MPa, where the initially formed MA intermediate can be easily hydrolyzed to form AA. A higher dispersion of the incorporated rhodium nanoparticles in the g-C₃N₄ matrix with a small crystallite size was responsible for a higher catalytic activity with a less leaching degree of active rhodium metals. The novel Rh-g-C₃N₄ with rhodium content of 1–3 wt% can be a candidate to substitute the commercial homogeneous Rh complex catalyst for AA production by methanol carbonylation.