I can't  open the article so I don't knw what eqns 15,11 and 17 are but you could try to model the two equilibrium reactions (11 and 17) as kinetic reactions with very high forward and reverse reaction rates at least at first to get the model going.  You could even do it in an Excel spreadsheet firs to get a better insight into what could be going wrong.

I suspect you probably have a set up problem in a way that doesn't allow kinetic and equilibrium reactions to be combined.   I have seen that problem in Hysys but I don'thave any recent experience with Aspen plus

Thanks a lot, certainly I can try forward and reverse reaction kinetcs to realise psued-equilibrium condition.

Maybe similar problem occured in my ASPEN PLUS, how did you fix it in HYSYS?

in eq 15, aspen + needs P-C6H6 and methane to calculate reaction rate (r), which are not available via your given reaction (eq.9). in other words,proper rate equation is not provided for aspen+ to perform simulation. Moreover, eq.9 is a rate determining step and you are recomended to use eqs (1 to 7) which are elementary steps.

In Hysys combining equilibrium and kinetic reaction is clumsy you can do it with high forward and reverse rate constants or you can string together kinetic and equilibrium reactors in series or you calculate  R ate =  K(X-Xeq ) in a spreadsheet.

>Mr. Yadollah Tavan

I thought the eq.15 represents total reaction rate to generate Benzene. Is it wrong? As reaction proceeds, P-C6H6 increases from zero because this reaction is in PFR.

And you recommended using eq (1 to 7). Could you tell me how to imput equations which include adsorbed substances like CH4-S1 in eq.2.

>Mr. Rick Manner

Thank you, I'll try it.