Abstract: The performance of NNI-1 Pd/molecular sieve catalyst applied in 0.2 Mt/a C5/C6 isomerization unit of SINOPEC Hainan Refining & Chemical Co. Ltd.，before and after regeneration was introduced. The NNI-1 catalyst was run for 3 periods and then regenerated ex-situ. The total time of operation for the first and second periods was 7 years. The inlet temperature of isomerization reactor was controlled under 250 ℃, while the temperature rise of catalyst bed was maintained in the range of 10-15 ℃; the RON of isomerized oil reached 78, 6 units higher than the feed; the C5 average isomerization ratio was 58.15%, and C6 average isomerization ratio was 73.32% with a 2,2-dimethylbutane selectivity of 14.78%. While at the EOR of the third period the RON increase of isomerized oil was less than 1 unit; the average isomerization ratio of C5 reduced to 43.96% and isomerization ratio of C6 was 51.42% with a 2,2-dimethylbutane selectivity of 2.42%, indicating that NNI-1 catalyst was no longer meet the needs of production. After regeneration ex-situ, the NNI-1 catalyst was run again for almost one year. In the case of high load operation, the inlet temperature of reactor maintained at 240 ℃, the temperature rise of reactor bed reached 18.7 ℃, the RON of isomerized oil recovered to 78, the average isomerization ratio of C5 recovered to 60.87% and C6 to 70.22% with the 2,2-dimethylbutane selectivity of 15.49%. The performance of the catalyst after regeneration indicates the well recovery in reactivity and stability meets the need of production.

Key words: C5/C6 alkane isomerization, catalyst, regeneration, octane number