Mining industrial materials as heterogeneous catalyst for high value‐added cyclic carbonates production from CO₂

Abstract

Chemical fixation of CO 2 and its utilization as C1 building block into fine chemicals are among key areas of research to mitigate greenhouse gas effect. The catalysts requirement to form cyclic organic carbonates by coupling reaction between CO 2 and epoxides is a well-stablished strategy for CO 2 fixation. In this work, this coupling reaction has been investigated using a catalytic system comprised by a selected industrial mining raw material, with potential valorization interest, and a commercial cocatalyst. Herein, industrial mining raw materials are explored as a renewable, recyclable, nontoxic, cheap, and ready-available catalysts for the transformation of CO 2 into highly valuable products such as cyclic carbonates. Initial experiments with the mining materials and alternative by-products of industrial valorization interest were carried out using propylene oxide (OP) as an initial selected oxirane. The most active raw materials were fully characterized to study their morphology, composition, and surface hydroxyl groups to determine active basic sites as novel heterogeneous base catalysts. The achieved yield of cyclic carbonate in these preliminary experiments was observed in the range of 37-85% for the different tested catalysts. In the case of the most active by-product used as catalyst (Sulfamag), propylene carbonate reached the yield of 85% as a higher result obtained under mild conditions. Sulfamag was selected to optimize reaction conditions, including the study of different cocatalysts. Moreover, coupling reactions between CO 2 and other aliphatic and aromatic epoxides were also performed efficiently for Sulfamag, showing yields between 71 and 91% and selectivity of 99% under mild conditions, demonstrating their potential as a renewable raw material solid-based heterogeneous catalyst in the synthesis of different cyclic carbonates from CO 2 and epoxides. Furthermore, Sulfamag showed high recycling efficiency in a test of four cycles and the deactivation of