Synthesis of diethyl carbonate from ethanol and CO2 over ZrO2 catalysts

Abstract

Diethyl carbonate (DEC) is a versatile chemical with several commercial uses. The synthesis of DEC from carbon dioxide and ethanol is both environmentally friendly and can be integrated into the ethanol biorefinery. A thermodynamic evaluation was made to predict the amount of DEC produced at equilibrium at the reaction conditions used in this work. Zirconium oxide solids were prepared using sol-gel methodology and were loaded with Na, Mg or PO 4 −3 using the incipient wetness impregnation method. Catalytic tests were carried out in a 500 mL stainless steel Parr reactor at 423 K. The DEC yield decreased as the Na or Mg load increased, while increasing the yield of acetaldehyde. However, DEC yield and selectivity increased as the PO 4 −3 load increased, while the acetaldehyde yield decreased. Lower overall acid site density and lower than 2.8 µmol-CO 2 /m 2 basic site density resulted in a higher DEC yield. Keywords Ethanol • CO 2 • Diethyl carbonate • Zirconia List of symbols C p Specific heat (kJ mol −1 K −1) ∆ r C p Specific heat of the reaction (kJ mol −1 K −1) D BJH BJH desorption diameter (nm) ∆G o f,i Gibbs free energy of formation (kJ mol −1) ∆ r G o 298 Reaction Gibbs free energy at 298 K (kJ mol −1) ∆ r G o T Reaction Gibbs free energy at temperature T (kJ mol −1) ∆H o f,i Standard formation enthalpy (kJ mol −1) ∆ r H o 298 Reaction enthalpy at 298 K (kJ mol −1) ∆ r H o T Reaction enthalpy at temperature T (kJ mol −1) v i Stoichiometric coefficients K eq Reaction equilibrium constant (cm 3 mol −1) p v Pore volume (cm 3 g −1) R Universal gas constant (kJ mol −1 K −1) [EtOH] 0 Ethanol concentration in the liquid phase (mol L −1) S BET B.E.T. surface area (m 2 g −1) V l liquid Molar volume (cm 3) V g gas Molar volume (cm 3) V t Total pore volume (cm 3) Greek letters λ X-ray wavelength (nm) 2θ Incidence peak angle in XRD (o)

Product Yield Increasing More Than 20 Times Achieved by Reducing Water Poisoning for Direct Diethyl Carbonate Synthesis

“…As shown in Figure , the main catalysts − were CeO 2 , ZrO 2 , and supported catalysts. To research a new preparation method to obtain the desired structure of CeO 2 or ZrO 2 , the DEC yield was slightly improved.…”

“…Literature reported for the DEC synthesis reaction from CO 2 and ethanol without third additives from 2015 to the present. − …”

A multifunctional carrier for composite ZnFe2O4: a catalyst for improved one-step diethyl carbonate synthesis from CO2 and ethanol

“…From these recent references, it was found that ethanol conversion and DEC yield remained at a low level. The best DEC yield was reported in reference 20 published in 2021. Nevertheless, 2-cyanopyridine was used in this DEC synthesis reaction.…”

Novel ZrFe2ZnO6 with multiple functional composite supports for one-step synthesis of diethyl carbonate from CO2 and ethanol

“…There are many third monomer candidates, and the best one among them is 2-cyanopyridine. 31 However, 2-cyanopyridine is more expensive than DEC and its consumption rate is also very high. 32 As such, it is not economical to use 2-cyanopyridine for the commercial production of DEC. At present, the main challenge of the synthetic route using CO 2 and ethanol is the low DEC yield.…”

“…As shown in Table 1, the synthetic conditions can be generally divided into two groups, with or without a third monomer. 8–31 A third monomer can help improve the yield of DEC. Without a third monomer, the ethanol conversion rate is usually very low, ranging from ca.…”