Ultra-deep hydrodesulfurization of kerosene for fuel cell system (part 1) evaluations of conventional catalysts

Catalysts for conventional hydrodesulfurization (HDS) were evaluated for us e in effective ultra-deep HDS (UD-HDS) of JIS No. 1 kerosene to attain sulf ur content of 0.1 wt ppm maximum under below 1 MPaG. Analysis of the JIS No . 1 kerosene showed a wide sulfur distribution consisting light to heavy su lfur compounds. Then, the original reaction order of kerosene, n = 1.3 in t he refinery, changed to n = 2.0. A concentrated Ni-Mo/ Al2O3 catalyst for p etroleum middle distillates was selected as one of active parts of a combin ed catalyst for large phosphoric acid fuel cell (PAFC). A tailor-made Ni-Mo /Al2O3 catalyst that was improved to meet the HDS of the large sulfur compo unds proved to clear the target. To keep the activity of Ni-Mo/Al2O3 cataly sts, a recycling procedure of H2S became necessary, which may be difficult in a small PAFC package. An adsorptive HDS using a conventional HDS catalys t without pre-sulfurization was more active than the usual HDS using the pr e-sulfurized catalysts. The catalyst, however, could not realize the target . On the contrary, an adsorptive HDS using a reduced Ni catalyst was most a ctive in this study. The life of the reduced Ni catalyst is short for a pra ctical long operation. However, the catalyst showed a possibility to develo p a new Ni catalyst, and seemed hopeful for a large PAFC combining with the conventional concentrated Ni-Mo/Al2O3 catalyst. Further, in the sensitive UD-HDS experiment, some poisonous compounds from the caulking of the metall ic cans were found.