| C5/C6 isomerization process is used to convert normal paraffin feedstock into corresponding iso-paraffins so as to improve the octane number of gasoline and make gasoline have uniform antiknock performance. Isomerized gasoline is the cleanest high-octane gasoline component, which is free of sulfur, olefin and aromatics. There is no actual ability of producing isomerized oil up to now, but the isomerization technology will become the most effective means of producing clean gasoline for our petrochemical enterprise. The core of isomerization technology is catalyst production. The commercialized catalysts in the world are divided into two groups, i.e. low-temperature and moderate temperature types, with Pt as their active metal components. Although the activity of moderate temperature catalyst is less than that of low temperature catalyst, it demands not too much on feedstock and can be regenerated. This catalyst can find wide application in China since both the investment of plant and its operation cost are low.Based on the studies of moderate temperature isomerization catalysts carried out by domestic and foreign researchers, the paper systematically discussed the influence of a variety of factors in process of commercial preparation on the performance of catalyst which applied Pd as its metal component and HM as its acid carrier. The paper also explored the deactivated reasons of catalyst and its regenerating measure. Preparation of mordenite and scaled up production of catalyst, stability of catalyst was demonstrated in a 100kt/a commercial plant. The findings provide important basis for preparing Pd isomerization catalyst and industrial application. Mordenite has a significant effect on the activity of catalyst, results of test showed: with soluble glass as main feedstock and addition of crystal precursor, thecrystalization time can be reduced, and the synthesized mordenite has higher surface area and structure of small crystal particulate and big pore diameter. Through ion exchange with ammonium and acid, the synthesized mordenite is suitable to prepare isomerization catalyst. The Pd/HM catalyst prepared through mixed pinching method has higher isomerization feature. With the use of this kind of catalyst, the isomerization reaction is carried out as the mechanism of carbocation,because Pd offers site for hydrogenation and de-hydrogenation, HM provides acid site. Within the range of 0.25-0.5% Pd content, the catalyst has good stability, isomerization rates of C5 and C6 are >62% and >82%, and selectivity of C6 is >18%, respectively. Applying activity evaluation of micro-reaction test and online chromatography analysis, X-RF,X-RD,FT-IR,BET,NH3-TPD and element analysis, the deactivated reasons and regeneration method of the prepared catalyst were investigated, and the pore structure, crystal phase, surface acid were characterized. The results showed: coking was the main reason of deactivation of Pd/HM catalyst,the deposition of coke on Pd site and acid site not only reduced the quantities of Bronsted acid sites and Lewis acid sites,but also covered the surface of catalyst resulted in reduction of micropore；while sulfur was the main factor poisoning Pd/HM catalyst since the sulfur in the feedstock combined with Pd so that active site of catalyst was covered and causing the decrease of catalyst activity. The deactivated catalyst was regenerated at 550℃ by coke-burning,and its majority of activity could recover. If the regeneration temperature was over 550℃,the surface area, pore volume, cell constant of catalyst would decreased, and the metal particulate became bigger, dispersion and number of acid site were weaken. The 0.5%Pd/HM catalyst produced through commercial scale-up possesses have better stability and sulfur-resistant characteristics. Results of life test indicated that the activity had not decreased with reforming topped oil containing near 50ppm sulfur as feedstock after 1000 hours' operation. Pd/HM catalyst was the first moderate-temperature isomerization catalys...
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