Process for Monitoring Separation of Ethanol Mixture

A process for effecting process control in a distillation column for separating a reaction mixture produced by hydrogenating acetic acid to form ethanol, wherein the reaction mixture comprises ethanol and acetic acid, the process comprising the steps of:

• measuring a conductivity of a condensed distillate of the distillation column, wherein the condensed distillate comprises ethanol and acetic acid;
• controlling at least one parameter of the distillation column in response to the measured conductivity;
• setting a baseline conductivity value for the condensed distillate and comparing the measured conductivity with the baseline conductivity value;
• returning the condensed distillate to the distillation column based on the measured conductivity;
• and
• recovering ethanol from the condensed distillate.

A process for producing ethanol, comprising:

• hydrogenating an acetic acid feed stream in the presence of a catalyst to form a crude ethanol product;
• separating at least a portion of the crude ethanol product in a first column into a first distillate comprising ethanol, water, and ethyl acetate, and a first residue comprising acetic acid;
• separating at least a portion of the first distillate in a second column into a second distillate comprising ethyl acetate, and a second residue comprising ethanol, water, and at least one organic impurity;
• separating at least a portion of the second residue in a third column into a third distillate comprising ethanol and a third residue comprising water;
• measuring the concentration of the at least one organic impurity using one or more on-line analyzers;
• and
• adjusting at least one column parameter of the second column to maintain the organic impurity concentration below 1 wt. %.