Study On Industrial Application Of Catalyst RIC-200 For C₈ Aromatics Isomerization To Para-xylene

Xylene isomerization is the main technology to produce more para-xylene. A special isomerization catalyst (RIC-200) for C8 aromatics into para-xylene was developed and applied in commercial unit. RIC-200 is a bifunctional catalyst with zeolite and platinum metal and can convert xylene mixtures with low content para-xylene into the mixtures closing to thermodynamic equilibrium composition. At the same time, it can convert ethylbenzene into xylene selectivitily. Based on the experimental study, molecular sieve content, platinum content, and the sodium ions exchange degree of molecular sieve in catalyst are determined. The optimum technical conditions are as follows:initial temperature 360-370?, the initial partial pressure of hydrogen 0.5-0.6MPa,WHSV 3.5h-1, hydrogen to hydrocarbon molar ratio 3.5-4.5. The application results in a aromatics complex unit of Shanghai petrochemical company show that the activity and selectivity of the catalyst are closely related to reaction temperature and pressure. During the first phase of catalyst activity, the lower temperature and pressure are favorable for the high reaction selectivity in the condition of suitable H2/HC. The appropriate operation parameters in earlier operation phase are temperature 377?, pressure 0.85 MPa, H2 concentration of circulation 80v%. The formal industrial application of the catalyst is assessed by the 72 hours continuous operation. The results indicate that the isomerization activity is 23.0%, conversion of ethylbenzene is 23.2%, the once-through yield of C8 aromatics is 97.6%, para-xylene yield is increased by 4.4% and energy consumption is decreased. The expected goal to study a catalyst for C8 aromatics into para-xylene xylene is achieved...