Studies On Removing Thiophene From Model Oil By Solid Super-acid Catalysing Condensation Reaction

Liquid fuel (gasoline, diesel and air oil) is an ideal energy carrier for transportation tools because of its high energy density, readily availability, safety, and ease of storage. However, the sulfuric compounds contained in fuel can poison the pollution control catalyst leading to more emission of pollutant. Especially, SOx is harmful to human health and causes acidic rain. Deep desulfurization of transportation fuels has already been a serious problem to be solved. The U.S. Environment Protection Agency demands reductions of sulfur contents in the diesel fuel from the current average of 500 to 15 ppmw by 2007, and from 350 to 30 ppmw in gasoline. Similar stringent regulations are being implemented in Europe and Japan. Pursuit of sulfur-free fuels has been a target of all countries in the world. Thiophene and its derivatives in the fuels are difficult to remove by the industrial technology presently applied in refineries, therefore, removal of them is the core problem for deep desulfurization.By the method of Hydrodesulfurization used in the industuial, thiophene and its derivatives are the most difficult to remove, but they are more proportion of the sulfur compound.A method of removing thiophene, which was based on a condensation reaction with formaldehyde that only thiophene and its derivatives of the fuels can occur,was presented. Solid super-acids are used as catalyst. The reaction of thiophene and formal dehyde yelid rosin and sdsorbented, as a result of this, the thiophene was removed. The solid super-acids studied are SO₄^2-/Al₂O₃>SO₄^2-/ZnO>SO₄^2-/ZrO₂>SO₄^2-/Fe₂O₃ > SO₄^2-/TiO₂. In the condition of 70℃,reaction for 3-5 hours, SO₄^2-/Al₂O₃ can remove the thiophene in the model oil (2000ppm thiophene in n-octane)out. And silica gel supporting formaldehyde and H3PW12O40 can remove thiophene from model oil(2000ppm thiophene in 80% n-octane and 20% benzene) in two hours.