Mechanism of hydrodenitrogenation. Part 1, Preparation and characterization of acidic supports.

摘要

Hydrocarbon feedstocks for energy production are currently obtained mainly from heavy petroleum crudes. To a lesser extent today, but of greater importance in the future, are fuels obtained from coal liquids, shale oils and tar sand oils. A common denominator to all of these feedstocks is the high content of S-(primarily in petroleums), N-(primarily in coal liquids and heavy oils) and O-heterocyclic aromatics. Those heteroaromatics must be decomposed, and S, N and O compounds must be removed from feedstocks for various reasons: they poison the reforming catalysts used in refineries, they induce polymerization of unsaturated compounds and form gums during combustion, they produce corroders in combustion engines, and they form environmental pollutants. Thus major effort has been allocated to the development of catalysts that selectively desulfurize, denitrogenate and deoxygenate fuel feedstocks. A method was developed to prepare silica, r-alumina, and amorphous silica-aluminas of compositions varying from 10% wt % silica to 90 wt % silica. All samples were highly homogeneous, were produced in high yield, and were dense enough for further use as a catalyst support material. The materials were characterized as per their BET surface area, total acidity, acidity strength distribution and type of acidity. The uniform preparation technique allowed the production of a set of silica-aluminas with smoothly varying acidity as a function of composition. 2 refs., 7 figs., 2 tabs.