Influence Of Post-treatment On Ring Opening Of Decalin Over Pt/Beta Catalyst

Diesel plays an important role in the consumption of different transport fuels. Currently, development of green high quality diesel has been highlighted. High quality diesel should have the perperties with high cetane number and low combustion emissions. It has become an important approach to improve the high cetane number by selective ring opening of naphthenics into alkanes and alkylnaphthenes. The acid sites and metal sites of bifunctional catalyst play an important role in the ring opening of naphthenics. Therefore, exploring the role of the acid distributions and metal sites of zeolites is very important to develop new high performance catlayst.The influence of dealumination and dealumination-desilication of beta zeolite on the ring opening of decalin was firstly investigated. It has been found that dealumination led to the increase of crystallinity and surface area, and the decrease of the acidity; dealumination-desilication of beta zeolite made the crystallinity decreased and the topology of the part of catalyst partially collapsed at high dealumination. All the modified catalysts were evaluated for the ring opening of decalin. It was found that the catalysts treated by dealumination and desilication had a higher stability and activity. Among the dealuminated catalysts, the catalyst treated with 0.1M HCl solution(β-0.1DeAl) showed the best selectivity of ring-open products and catalytic stability. But the highest yield of ring-open products, 33.9%, was obtained on the dealumination-desilication catalyst with 0.3M HCl pre-treatement(β-0.3DeAl-DeSi) due to the introduction of moderate mesopore.The influence of acid sites on the ring opening of decalin was explored by controlling the ion exchange degree of Na-Beta zeolite with differen NH4 Cl concentration.. It was found that L acid sites has no effect on the ring opening of decalin and moderate B acid sites contributed to the formation of ring open products. The isomerization of decalin was dependent on the total B acid sites. High density of acid sites would lead to quick deactivation of the beta zeolites.Finally, the influence of water-alcohol cosolvents on the state of metal sites by incipient wetness impregnation and its catalytic performance was investigated. With the water/alcohol=5:5, the Pt particle size with less than 10 nm uniform spherical morphology was obtained on the zeolites. As alcohol content in the cosolvent increase, the large agglomerated Pt particles was formed and the morphology were mostly cubes. The catalytic experiments showed that the Pt particles with uniform spherical morphology and size was prone to formation of ring open products, and the opitmal yield of isomeriztion products was also obtained over this catalyst. The catalysts prepared with different water-alcohol cosolvents greatly improved the activity and stability of catalysts. Comparing with the catalyst obtained by pure water, the big cubic Pt particles also contributed to the formation of ring opening products, but the activity was lower than that catalyst with small uniform spherical metal particle size.