III International Conference

PP-I-78condensed (Н ark ) and bicyclic (Н arb ) component and increase in content of monoaromaticalkylbenzenes (H am , Н av ) and naftenic hydrocarbons (Н n ).It has been established that the increase in operation temperature by 30 0 С results in thechange of process efficiency, as the decrease in values of structural parameters Н arg , Н ark , Н avand Н arb as well as the increase is ones of Н arm , Н n , Н v were observed. It might be assumedthat in this case polyarenes decompose to molecules with smaller number of rings, and theheteroatomic and monoalkylaromatic compounds are hydrogenated. Residual aromaticcompounds of the hydrotreatment products are presented by less condensed with loweredcoke ability.Sulfur presents in diesel fuel substrates is forms of condensed thiofene compounds,sulfides and disulfides and its removal has to be done by the hydrogenation. For the catalystsstudied a symbatic change in the depth of removal of sulfur and the decrease of amount ofaromatic hydrogens of condensed system has been observed. At the same time, depending onthe catalyst composition a different ratio of these two processes is observed, which may bemarkedly noted by the comparison of sulfur and Н arb concentrations.For a series of samples at rather close values of Н arb , Н ark +Н arg parameters divorces indepth of desulfurization are valueble (~70 %). Observed regularities prove the commonlyaccepted concept that the hydrogenation and C-S bond clearage proceed with different activespecies and the hydrodesulfurization is proceeded in two ways: one suggests the formationof hydrogenation products in the first step without С-S bond cleavage, and according toanother С-S bond cleavage precedes the hydrogenation of hydrocarbon maioties. The amountof products of certain transformation should be dependent on the catalyst properties and firstof all, on the ratio of hydrogenating action and cracking – the abilities to С-S bond cleavage.The change in Н n parameter is abigious. Hydrogenation of aromatic compounds givesrise to an increase of amount of naphtene hydrocarbon (Н n ), while the cracking leads to adecrease. At the same time at simultaneous increase both hydrogenationg and crackingactivitives of catalysts the parameter remains unchanged.147