Hydrotreatment-isomerization without hydrogen recycle

摘要

A combined process for hydrotreating and isomerizing a C4-C7 feedstock is simplified and made more efficient by the use of a common hydrogen source and low hydrogen to hydrocarbon ratio in both the hydrotreating and isomerization steps of the invention. The method supplies hydrogen to a combined hydrotreatment and isomerization process for the isomerization of a feed stream comprising C4-C7 hydrocarbons. The hydrocarbon feed stream contains sulfur and oxygen contaminants and is combined with a hydrogen-containing stream in an amount that produces a maximum hydrogen to hydrocarbon ratio of 0.9 stdm3/m3 (50 SCFB). The hydrotreater feed is contacted in a hydrotreater reactor with a catalyst comprising a Group VIB metal and a Group VII metal on an alumina support. Effluent from the hydrotreater passes to a first separator that separates the effluent into a first gas stream comprising hydrogen, hydrogen sulfide and water and a treated stream comprising hydrocarbons having from 4-7 carbon atoms. The first gas stream is rejected from the process. The treated stream is mixed with a second hydrogen-containing stream in a proportion that produces a hydrogen to hydrocarbon ratio of from 0.9 to 1.8 stdm3/m3 (50 to 100 SCFB) to form an isomerization zone feed. The isomerization feed is contacted in an isomerization reaction zone with an isomerization catalyst comprising alumina having from 0.01 to 0.25 wt. % of platinum and from 2 to 10 wt. % of a chloride component at isomerization conditions. The effluent from the reaction zone enters a stabilizer where it is separated into a product stream of C4-C7 hydrocarbons and a second gas stream which is removed from the process. The common hydrogen supply source and the low hydrogen to hydrocarbon ratios permit operation of the process without hydrogen recycle facilities between the hydrotreatment and isomerization steps and downstream of the isomerization reactor.