AM-97-54 HIGH OCTANE ALKYLATE FROM FIELD BUTANES THE SNAMPROGETTI ISOETHER PROCESS

Description:

This paper describes the SNAMPROGETTI ISOETHER DIMERIZATION/ ETHERIFICATION PROCESS (SP ISOETHER DEP) to simultaneously produce ISOOCTANEGAS, a high quality alkylate, and MTBE (or ETBE). ISOOCTANEGAS is an Isooctane based ether-free mixture containing about 90% of highly branched CS hydrocarbons (mainly Isooctane) together with some higher hydrocarbons (mainly tri-isobutanes). ISOOCTANEGAS is derived by the hydrogenation of an Isooctene mixture containing about 90% of Cd olefins dimers (mainly di-isobutylenes, or Isooctene) together with minor amounts of tri-isobutylenes. The properties of ISOOCTANEGAS (containing large amounts of Isooctane) resembles very nearly those of normal Alkylate, but are better due to some improvements. Isooctane is the compound having by definition the following octane rating: Clean RON = Clean MON = 100. Although its blending properties are generally slightly different, its high Octane Number as well as the absence of Sulphur and Aromatics makes it one of the most attractive compounds of a “Cleaner Burning Gasoline”. The following route (Figure 1) is a very easy industrial route to produce Isooctane. The process consists of two reaction stages and produces both ISOOCTANEGAS and MTBE (or ETBE). In the first reaction (Dimerization and Etherification) the Isobutylene contained in a Cd stream coming from any source (Steam Cracking afler Butadiene removal, fluid Catalytic Cracking or Isobutane Dehydrogenation) is partially etherified into MTBE (or ETBE) and partially dimerized into Isooctene. ‘. In the second reaction, Isooctene (which is a mixture of the two isomers 2-4-4-trimethyl-lpentene and 2-4-4-trimethyl-2-pentene) is hydrogenated into Isooctane (mainly 2-2-4- trimethylpentane). The Dimerization and Etherification step is carried out in a Snamprogetti Water Cooled Tubular Reactor (WCTR). The Hydrogenation step makes use of an innovative BASF technology. In Section 2, Technology, the properties of ISOOCTANEGAS are more extensively described. However, the following summarizes some advantages of SP ISOETHER DEP compared to those of normal Alkylation processes: - ISOOCTANEGAS has higher blending Octane properties compared to normal Alkylate. - It has lower volatility as compared to normal Alkylate. - The ISOOCTANEGAS production is “environmentally friendly” because the hazards coming from handling Hydrofluoric Acid or Sulphuric Acid in the normal Alkylation processes are completely removed.