Is molecular structure a required input when estimating physical properties?

Importing the next MOL file will do it

Reply to 2# uxufk_jtg: My question is as follows. I want to define a type of oil; the formula I derived is C25.7H44.43O0.463N0.335S0.058, which can be simplified to C26H44 as needed. This substance does not exist in the database. For this substance, I need parameters such as heat of combustion, enthalpy of formation, density, and boiling point; detailed data such as the molecular structure is not required. Of course, since it is a mixture, it also doesn’t have a definite molecular structure. These are my specific questions. For the estimation of physical properties, can I ignore the molecular structure? Or are those items mandatory?

Reply to 3# abner001: Since it’s possible to determine the average molecular formula from your question, you should also be able to know the approximate distribution of each substance. You can make a rough estimate by using their main components and performing manual calculations (such as for density); there’s no need to use ASPEN. Below are the warnings I received when I didn’t define any parameters: * WARNING IN PHYSICAL PROPERTY SYSTEM: THE FOLLOWING CONVENTIONAL COMPONENTS WERE NOT FOUND IN THE DATA BANK. CHECK THE SPELLING OF THE DATA BANK NAMES. CID DATA BANK NAME: US-1, C26H44 * WARNING IN PHYSICAL PROPERTY SYSTEM: MW AND GENERAL STRUCTURE INFORMATION ARE MISSING FOR COMPONENT US-1. FOR BETTER RESULTS, ENTER THE MW, TB, AND GENERAL STRUCTURE INFORMATION. * WARNING IN PHYSICAL PROPERTY SYSTEM: MW INFORMATION IS MISSING FOR COMPONENT US-1. I remember that the ASPEN user manual contains very detailed instructions; I don’t have that document with me at the moment, so it’s difficult for me to give a definite answer. Furthermore, selecting key components to estimate these parameters is a very effective approach.

Reply to 4# uxufk_jtg: First of all, I would like to thank LS for their generous assistance. The substance I want to define is shale oil – the product of the dry distillation of oil shale. Shale oil is similar to petroleum and is also a very complex mixture; there are over 20,000 different components in such mixtures. I once checked the components of coal tar and found that there are approximately 13 substances whose mass fraction is 1% or higher, but the combined mass fraction of these substances is less than 40%. For physical properties of shale oil such as density, viscosity, and boiling point, I can look them up or conduct experiments to measure them myself. Just the atomic structure of matter is already complicated; as a mixture, it probably doesn’t have any atomic structure either. Additionally, you went the extra mile to conduct a property estimation based on the information I provided above. Since this is my first time dealing with property estimation, I’m not very familiar with it. I downloaded a textbook on property estimation prepared by Jiaxing University and tried to carry out the calculations myself yesterday, but I encountered many problems. Based on your experience, those parameters are the ones I must enter in order to avoid errors and issues during operation. My QQ number is 85917679; if it’s convenient for you, I would really like to discuss this with you. (Please mention HaiChuan ASPEN.) Thank you again for your generous help.

Reply to 5# abner001: I also use property estimation quite rarely. Generally, at least three pieces of information are needed to estimate properties – molecular structure, molecular weight, and standard boiling point; relevant references can be found in Aspen’s help files. However, I suggest using known key components along with a virtual component for simulation first. Specific solutions await enthusiastic discussion from everyone!

Your shale oil can be described using several substances; if only one substance is used, then it will have to form rings. Based on your molecular formula, it is already highly unsaturated

Reply to 7# dzzlurker: I have also considered using certain substances to represent shale oil, but there are an extremely large number of different compounds in shale oil, making it difficult to select just a few substances to use as substitutes. As I mentioned earlier, taking coal tar as an example, there are approximately 13 compounds in coal tar whose mass fraction exceeds 1%, yet the combined mass fraction of these compounds is less than 40%. (Shale oil and coal tar are both products of the dry distillation of oil shale and coal respectively, and their compositional elements are similar to those of petroleum.) Therefore, such substances cannot effectively serve as substitutes for shale oil. Thank you very much for your advice; I hope you can continue to help me

Reply to 6# uxufk_jtg: Could you give a brief introduction to small virtual components? I noticed it while looking at some materials before, but I never really understood it well. Also, how should I use virtual components to achieve my goals?

This post was last edited by Albertlu on 2011-6-25 at 11:11. In response to the original poster’s question regarding parameters such as heat of combustion, enthalpy of formation, density, and boiling point – data that do not require detailed information like molecular structure – it should be noted that since it is a mixture, it does not have a definite molecular structure. ------------------------ The discussion is as follows: It is impossible to estimate the above-mentioned values without knowing the structure. The solution is to conduct experiments to determine the temperature and weight ranges of the distillation fractions; by defining virtual petroleum components, complex mixtures can be simulated.

Reply to 8# abner001: To characterize something, you need to know some of its properties; just like with coal, once you know its mass composition, you can characterize it