Heterogeneous azeotropic distillation is an effective technology to separate close boiling point or homogeneous azeotropic mixture.The first step is to select appropriate entrainers.A computer aided molecular design(CAMD)methodology for the entrainer in heterogeneous azeotropic distillation is presented in this study.The CAMD methodology is comprised of three step-by-step stages

which are molecular synthesis

molecular screening and molecular recognition.In the stages of molecular synthesis

groups are pre-selected

the total number and types of the groups for the synthesized molecule are limited

and the automatic combination of groups is completed by using a graph algorithm.In the stages of molecular screening

the basic molecular library is formed by using several limited rules of basic physical properties

such as molecular weight and boiling point.The molecules in the basic molecular library are screened when they form the heterogeneous azeotropic with input components to be separated.As a result

a series of entrainer candidates are listed.In the stages of molecular recognition

the fuzzy comprehensive assessment function

which is composed of several important factors

such as temperature and composition of heterogeneous azeotropic point

and heat of vaporization of entrainer

is used to rank entrainer candidates.Consequently

a group of appropriate entrainers are obtained.For acetic acid-water system and acetonitrile-ethyl acetate system

several better entrainers are obtained.It indicates that the CAMD methodology and the computer procedure is practical and reliable

and the resulting entrainers is the basis for research or conceptual design of heterogeneous azeotropic distillation processes.