The removal of sulfur and changes of sulfur forms in Oman vacuum residue by hydrotreating were investigated on a pilot plant.The results illustrated that the content of total sulfur in hydrotreated residue reduced gradually with the hydrotreating.Over 80% of total sulfur in the residue can be removed at three temperatures(T-5 ℃,T ℃,T+5 ℃),although a higher temperature can enhance the desulfurization effect.The residue fractions of aromatic,resin,asphaltene and saturate contain about 60%,32%,8% and 1% of total sulfur,respectively;however,the sulfur content in each fraction is in the order of asphaltene>resin>aromatic>saturate.The sulfidic sulfur content in the residue fraction decreased and the thiophenic sulfur content increased with the heaviness of residue fraction.Sulfur forms exhibit influence on the hydrodesulfurization effect;the removal of sulfidic sulfur is much easier than that of thiophenic sulfur.The residue fractions are also different in the desulphurization effect,depending on their molecular size and structure;the sulfur removal ratio of saturate and aromatic is higher than that of resin and asphaltene.
