Synthesis of glycerol carbonate from biodiesel by-product glycerol over calcined dolomite

- Natural dolomite decomposed to MgO-CaO mixed-oxide during calcination at 800 °C.
- Calcined-dolomite has superior bacisity and surface characteristics than natural dolomite.
- Glycerol transesterification with DMC on calcined-dolomite result to 94% maximum yield of GC.
- Calcined-dolomite is effective during the 4th cycles of the transesterification reaction.

Glycerol, which threatens the viability of biodiesel industries, can be converted to valuable chemicals and chemical intermediates, such as glycerol carbonate (GC). GC was synthesized by glycerol transesterification with dimethyl carbonate (DMC) on CaO-MgO mixed oxide catalyst prepared from natural dolomite. At calcination temperature of 800 °C, natural dolomite was converted to CaO-MgO mixed oxide to serve as catalyst in the conversion of glycerol to GC. Temperature changes and calcined dolomite surface and textural characteristics caused the glycerol transesterification with DMC to GC. The catalyst with 15< H_<18.4 basic strength yielded a maximum of 97% glycerol conversion and 94% yield of GC at 75 °C, 3 DMC/glycerol ratio, and 6 wt% catalyst dose. Calcined dolomite showed potential for a consecutive cycle of catalytic activity during glycerol transesterification with negligible yield of by-product glycidol.

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