Optimization On The Process Of MTBE Deep Desulfurization By Diesel Absorption

The continuous improvement of environmental protection requirements urges China’sgasoline quality standard to upgrade as gasoline is accounting for5%of the total energy useof vehicle. Restrictions on sulfur content of gasoline is getting more and more strict. Theforthcoming implementation of national IV standard for vehicle gasoline with sulfur contentlimitation of less than50μg/g, is expected to upgrade to national V standard with less than10μg/g sulfur content in2018.At present, the domestic gasoline pool is mainly composed of FCC gasoline，catalyticreforming gasoline, naphtha, MTBE and so on. Because of hydrotreating, the sulfur incatalytic reformed gasoline and naphtha is less than1μg/g. and sulfur content of FCC gasolinecan be reduced to less than10μg/g after S-Zorb treatment. Therefore the sulfur content ofgasoline oil is not the index limit factors, the main limiting factor is MTBE. For high octanenumber and good mixing performance and relatively high oxygen content, MTBE becomesthe main blending component of gasoline to increase octane number and oxygen containingcompounds, of which the oxygen has significant improvement effect to vehicle emissions.According to the request of gasoline mixed indicator, the mixed percentage of MTBE mustnot exceed15%. The raw materials of MTBE are the by-product of refinery mixed C4andethylene cracking by-product mixed C4, different material effect on the sulfur content varied.If using ethylene cracking by-product C4as raw materials, the raw materials and refinedprocess of MTBE products almost have no sulfur, so there is no adverse effect to gasolineblending. But when using by-product of refinery mixed C4as raw material, which has a largechange of sulfur mass fraction, usually100to300μg/g, some as high as2000to3000μg/g, thesulfur content in MTBE will be the key limiting factor for the sulfur index of gasolineblending. So as the national V motor gasoline standard implementation approaches, thedemand for sulfur reduction technology of MTBE production is becoming more and moreurgent.Based on the10×104t/a MTBE production unit in Hainan refining factory, this paper useabsorbent refined diesel to extract the sulfur of MTBE. In order to save energy and optimizeparameters during operation, the paper builds up peocess model by the simulation software ofthat ASPEN PLUS with practical production data of the factory. The total sulfur of MTBE canbe reduced to10μg/g by the model, which will solve the challenging problem during gasolineblending mentioned above.