Investigation Of Thermodynamics On Ethanol Synthesis And Application

Ethanol fuel has the advantages of low ash and low sulfur as a high quality fuels, andoffers the same chemical energy as that of gasoline. So, it is considered as a potential energyalternertives. The reaction of DME and MA is a new way for the ethanol synthesis, includingthe DME carbonylation and the MA hydrogenation. The process characteristics can be studiedwith systematic analysis which is also helpful for catalyst screening, process optimization andreactor designation.etc. In the present study, the standard formation enthalpy, the standardentropy and the molar heat capacity are estimated with the Benson group contribution methodand the R-D group contribution method. Reaction enthalpy change,reaction entropy change,reaction Gibbs free energy change and equilibrium constant of reactions of ethanol synthesis（DME carbonylation, MA hydrogenation, overall reactions） are calculated and analyzed in theconditions of298.15～1000K,1～3MPa. On this basis, the effects of temperature, pressureand feed composition on the synthesis of ethanol from DME and syngas ard investigated in awide range, at the same time, the synergistic effect of two reactions is investigated.Afterwards, thermal effect for the ethanol synthesis are computed and analyzed. Finally, thesaturated vapor pressure of ethanol in petrol is calculated by the group-contribution method.It is showed by the calculation that the conversion of DME in DME carbonylation canachieve100%at the298.15～573K,1～3MPa. The conversion of DME is ever-increasingwith the CO concentration in feed. The conversion of DME can reach99.98%when the COconcentration is0.5. The conversion of CO can achieve100%among the CO concentration0～0.35. It is showed that the conversion of MA in MA hydrogenation can achieve90%in theconditions of298.15～493.15K,1～3MPa and the conversion of MA is increased with therise of H₂concentration in feed. For the overall reaction, the equilibrium conversion in MAhydrogenation increased greatly due to this synergistic effect. The concentration of CH₃OHand C₂H₅OH in equilibrium gas can reach greatest value when the concentration of CO andH₂is33.3%and39.4%.The process of ethanol synthesis is exothermic reaction. The heats of DME carbonylationaccounts for24%for the heat of combustion of DME at573.15K. The heats of MA hydrogenation accounts for12%for the heat of combustion of DME when the COconcentration in feed is33%..The saturation vapor pressure of different proportions are measured with the way of theReid vapor pressure, and basis on this, the vapor pressure of the whole composition can becalculated by the Wilson equation.