ABSTRACT
Deep desulfurization of diesel fuels has become an important research subject due to the increasingly more stringent environmental regulations on diesel fuel specifications. The key to deep desulfurization is hydrodesulfurization of S-containing polycyclic compounds such as dibenzothiophene (DBT), 4-methyldibenzothiophene (4-MDBT) and 4,6-dimethyldibenzo-thiophene (4,6-DMDBT). This chapter explores new molecular sieve-based catalytic systems for deep desulfurization and deep hydrogenation of distillate fuels. It characterizes the Co-Mo/MCM-41 and Co-M0/Al2O3 catalysts by temperature-programmed desorption of a base probe molecule and by FT-IR of NO probe molecule chemisorbed on the catalysts. The amount of NO uptake on the sulfided catalysts was also measured by a conventional pulse method. Temperature-programmed desorption (TPD) of n-butylamine (n-BA) is a useful method for evaluating the acidity of zeolites. The chapter compares the relative acidity between supported Co-Mo catalysts by n-BA TPD for understanding their differences. Co-Mo/MCM-41 catalyst at high metal loading level is substantially more active than both the laboratory and commercial Co-Mo/Al2O3 catalysts.
