Catalytic direct reaction of Di-methyl, Di-ethyl carbonate with the natural silica-KOH mixture

Abstract EN

The present research involves the study of an important reaction of the di alkyl carbonate vapor with natural silica source powder.

It was performed in a static type reactor, and the gas phase resulting from the interaction was analyzed by using a mass–spectrometer partial pressure gauge.

The catalyst used was KOH mixed with powder of silica to the extent of 5 wt.

of the total composition.

After the dimethyl carbonate (DMC) or diethyl carbonate (DEC) was admitted to the SiO2-KOH mixture in small doses (10 -2–10 -1 mbar), the adsorption of DMC or DEC was found to be limited at temperatures > 250 °C.

The adsorption process was molecular at such temperatures and no products were detected in the gas phase.

On SiO2 without catalyst powder at the three temperatures (300, 350, 400 °C), the adsorption was found to be slight and accompanied by the formation of non – silicon products.

The adsorption of DMC on SiO2 – Catalyst mixtures increased and became extensive as the reaction temperature increased.

The products of the interaction were mainly.

tetramethoxysilane (TMS), dimethylether (DME), and CO2.

In the case of DEC interaction, the adsorption was slow in comparison with DMC and the products were mainly tetraethoxysilane (TES), diethyl ether (DEE), and CO2.

Kinetics of the reactions have been investigated over a range of pressures (4×10 -2 – 1.0 mbar) and temperatures (300 – 400 °C).

The reaction rate, activation energy, pre – exponential factor and entropy of activation of the interaction of DMC and DEC with different mixtures have been calculated.