Abstract
Glycerol is an attractive renewable building block for the synthesis of polyglycerols, which find application in the cosmetic and pharmaceutical industries. The selective etherification of glycerol to higher oligomers was studied in the presence of CaO colloids and the data are compared with those obtained from NaOH and CaO. The materials were prepared by dispersing CaO, CaCO3, or Ca(OH)2 onto a carbon nanofiber (CNF) support. Colloidal nanoparticles were subsequently dispensed from the CNF into the reaction mixture to give CaO colloids that have a higher activity than equimolar amounts of bulk CaO and NaOH. Optimization of the reaction conditions allowed us to obtain a product with Gardner color number <2, containing no acrolein and minimal cyclic byproducts. The differences in the CaO colloids originating from CNF and bulk CaO were probed using light scattering and conductivity measurements. The results confirmed that the higher activity of the colloids originating from CaO/CNF was due to their more rapid formation and smaller size compared with colloids from bulk CaO. We thus have developed a practical method for the synthesis of polyglycerols containing low amounts of Ca.
Highlights
Glycerol is a simple yet functionalized, renewable platform chemical that can be used as a building block for a large variety of commodity chemicals.[1,2,3,4,5] One such valorization route is the direct catalytic etherification of glycerol to polyglycerols
As can be seen from the results presented here, the contribution of the heterogeneous pathway can be optimized by dispersing CaO on carbon nanofiber (CNF), as the presynthesized colloidal nanoparticles are efficiently dispensed without an induction period, giving higher activities than equimolar amounts of bulk CaO would in the glycerol etherification reaction
We have developed a simple method for the synthesis of highly active Ca colloidal particles for the synthesis of polyglycerols by dispersing CaO as nanoparticles or thin films onto a CNF support
Summary
Glycerol is a simple yet functionalized, renewable platform chemical that can be used as a building block for a large variety of commodity chemicals.[1,2,3,4,5] One such valorization route is the direct catalytic etherification of glycerol to polyglycerols. It can be seen that all catalyst materials are active and that the glycerol conversion increases gradually as the loading of CaO on the CNF support increases.
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