Abstract:
The coke deposition of various contents of nitrogen(sulphide)in toluene under different reaction pressures on hydrocracking catalyst has been obtained using accelerated aging experiment. Coke type and amount, acid strength distribution, pore structure, and dispersion of active metal of catalyst were measured by elemental analysis, FTIR, physical adsorption, XPS, and TG/DTG. The results showed that the amount of coke increases significantly when the content of pyridine or thiophene is higher than 0.1% or 0.6% in toluene. The coke deposited due to pyridine accumulated mainly in small pores (<6 nm), and it decreased the amount of acid center especially strong acid center. The coke deposited due to thiophene impenetrated into all the pores and some of them could form mechanical pore on catalyst surface. When the content of thiophene was higher than 0.6% in toluene, thiophene could enhance the active-metal sulphidation and weaken the coke production. Higher reaction pressure could make coke deposited less abruptly, decrease the loss of acid center, but result in the ratio of pseudo-graphite structure coke increasing relatively.