The Bombay Technologist

Impact of Carbon Dioxide Pressurization on Catalytic Reactions

Shin-ichiro Fujita

Division of Chemical Process Engineering

Masahiko Arai

Division of Chemical Process Engineering

---

Abstract

The present contribution briefly describes several catalytic reactions in the presence of dense phase CO₂, which the present authors have studied in recent years. The reactions described are hydrogenation reactions of cinnamaldehyde, nitro benzenes and phenol, Heck coupling, and Diels-Alder reactions. Dense phase CO₂ affects the overall reaction rates and/or the reaction selectivity in different modes of manner depending on the reactions examined and the catalysts used. Such effects can be connected with interactions of dense phase CO₂ with the substrate and/or the catalyst. Phase behavior of reaction mixture is also significant for the reactions. The pressurization of liquid reaction mixtures with CO₂ is sometimes more effective than doing the reaction under homogeneous conditions in supercritical CO₂ for accelerating the rate of reaction and modifying the product selectivity.