Catalytic Conversion on Zeolites: Synthesis and Characterization

Rajangam Vinodh, Cadiam Mohan Babu, Aziz Abidov, Rramaswamy Ravikumar, Mei Mei Peng, Muthiahpillai Palanichamy, Wang Seog Cha, Hyun Tae Jang
2016 International Journal of u- and e- Service, Science and Technology  
In this present work, catalytic cracking of durene over HY and Hβ zeolites, and their silica modified forms was examined at the temperature of 450 C. The reaction was carried out in gas phase using a fix bed reactor. HY and Hβ zeolites showed high conversion because of their large pore size comparable to the kinetic diameter of durene. Silica modified HY zeolite showed a slight increase in selectivity, which is attributed to blocking of external acid sites. It is conceived that gradual
more » ... hat gradual increase in silica content could gradually enhance p-xylene selectivity. Similar effect could also be expected for Hβ zeolites. One can maximize toluene selectivity compared to p-xylene, but the latter is commercially more important than the former. This study depicts that other large pore zeolites could also be good to crack durene to p-xylene. Cracking of durene over ZSM-5 was not good due to its high kinetic diameter compared to the pore size of the later. With this zeolite the cracking is essentially due to external acid sites and availability of defective channel intersections on the external surface. HY and Hβ zeolites showed high conversion because of their large pore size comparable to the kinetic diameter of durene. Though conversion was good, selectivity of p-xylene was not high because of rapid diffusion of toluene through the pores. Based on the results it is expected that a slight decrease in flow rate of the feed could enhance pxylene selectivity. Addition of little amount of toluene to durene -benzene feed could also enhance p-xylene selectivity. So, use of different feed ratios of benzene and toluene could solve the problem of p-xylene selectivity. Silica modified HY zeolite showed a slight increase in selectivity, which is attributed to blocking of external acid sites. It is conceived that gradual increase in silica content could gradually enhance p-xylene selectivity. Similar effect could also be expected for Hβ zeolite. One can maximize toluene selectivity compared to p-xylene, but the latter is commercially more important than the former.
doi:10.14257/ijunesst.2016.9.5.35 fatcat:6rsjjphgarfnngvv3uv64yrs54