Preparation and Characterisation of Hierarchical Zeolite Catalysts

Content Provider	Semantic Scholar
Author	Lopes, Zélia Souza
Copyright Year	2017
Abstract	Diesel fuel is one of the most important fuels, given its high combustion efficiency (it has a strong tendency to autoignite). The blendstock for this type of fuels are middle distillates obtained from hydrocracking, thus the need to improve the efficiency of hydrocracking catalysts in terms of selectivity. Zeolite Y is the most widely used catalyst for these processes, due to its high thermal stability, density of acid sites and rather high acid strength. However, it also produces a large amount of light distillates. Hence, modifying zeolite Y to increase the mesoporosity can improve the yield of middle distillates: with bigger pores, more middle distillates can be obtained. The main goal of this work was create hierarchical mesoporosity in zeolite Y. The starting material was zeolite Y in the NaY form, and two different routes were experimented: Route 1, where the zeolite was ion exchanged to NH4Y form and then suffered an acid treatment to create mesopores and Route 2, where the zeolite suffered the acid treatment and was ion exchanged subsequently. In the end of both routes, a calcination step took place to remove the formed NH3. The following characterisation techniques have been used: N2 sorption, XRD, FTIR and SEM/EDS. In FTIR, two experiences were made: pyridine was used to characterise the acid sites in zeolite Y (number and type) and different probe molecules were used to test pore accessibility. Results have shown that Route 2 is preferable, since the loss of crystallinity was smaller and the amount of acid sites was higher. SEM/EDS results showed an increase in the Si/Al ratio, as expected, due to dealumination and a slight desilication by the acid treatment.
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Language	English
Access Restriction	Open
Content Type	Text
Resource Type	Article