The Industrial Application Of SKI-400D Isomerization Catalyst

Metaxylene is an important organic chemical product and the main producing method is the adsorption separation and xylene isomerization joint method. In this paper, the special isomerization catalyst (SKI-400D) for the production of metaxylene is studied and put into industrial application successfully for the first time.SKI-400D catalyst is a xylene isomerization catalyst on which ethylbenzene transforms to xylene. By the test in experimental stage, such important parameters as molecular sieve content, platinum content, and the exchange degree of molecular sieve are determined. The optimum technical conditions are as follows: temperature 380℃, the initial partial pressure of hydrogen 0.8MPa, WHSV 1.5h-1, hydrogen/hydrocarbon ratio 4.0～5.0(mol).For the first time, the catalyst is put into industrial application successfully with the modality of deoxidization. In the course of the industrial application of the catalyst, the research is focused on the influence of the process parameter on the performance of catalyst. The results indicate that the activity and selectivity of catalyst are closely related to temperature and pressure. In the first phase of catalyst activity, the lower temperature and pressure are favorable for the high selectivity in the condition of suitable H2/HC. A relatively ideal operation parameter in earlier operation phase is temperature 360℃, pressure 0.75 MPa, H2 concentration of circulation 80%.The formal industrial application of the catalyst is assessed by the 72 hours continuous operation. The results indicate that the conversion of ethylbenzene is 44.50% and the once-through yield of C8 aromatics is 97.10%, which are both prior to the contract. At the same time, the production of metaxylene is increased by 18.81%.