Modified Natural Dolomite and Its Influence on the Production of Glycerol Carbonate: Effects of Structural and Basicity Properties

A systematic study over different treatment conditions, including hydrothermal and acid-thermal, was successfully carried out to determine the most suitable conditions to enhance the textural properties and surface chemical composition of natural dolomite. The reconstruction of dolomite after various treatments enhanced the surface area by 4-5 times and diminished the pore diameter between 70% and 81% compared to the untreated parent dolomite. The Rietveld analysis of the X-ray diffraction (XRD) patterns revealed changes in the crystalline compositions after each treatment. When the treated dolomite was used as a catalyst to produce glycerol carbonate via a transesterification reaction of glycerol and dimethyl carbonate, the crystalline Ca(OH)(2) concentration of the modified dolomite and the apparent glycerol carbonate formation rate (r(gc)) are well-correlated. The results suggest that an increase of the crystalline Ca(OH)(2) concentration could be related with surface basicity at the weak and moderate strength sites that may lead to an increase in catalytic activity. The hydrothermal treated dolomite showed a selectivity of glycerol carbonate greater than 99% and r(gc) value 3.42 mmol/min center dot g(cat), which was higher than that achieved on other samples. This study could aid to the proper selection of dolomite treatment for the desired crystalline composition, depending on the applications of this highly available mineral.

Automated summary

The study successfully enhanced the structural properties and surface chemical composition of natural dolomite through hydrothermal and acid-thermal treatments, increasing surface area and decreasing pore size. Changes in crystalline compositions were observed using XRD analysis, and the catalytic activity was found to be related to the crystalline Ca(OH)2 concentration. This research can assist in selecting the appropriate dolomite treatment based on desired crystalline composition for specific applications.