New Insights into the Progress on the Isobutane/Butene Alkylation Reaction and Related Processes for High-Quality Fuel Production. A Critical Review

Abstract

Although research in renewables is growing at a tremendous rate, the world will still be greatly dependent on fossil fuels for at least the first half of this century. In the quest for more efficient and clean fuels, oil refining companies have turned their attention to processes such as reforming and alkylation technologies; in the latter process, isobutane is reacted with butenes and/or propylenes to produce, among others, branched isooctane, which is the main high-octane component of the gasoline pool. The main benefit of this process is the possibility to produce sulfur-free high-octane fuels, so important economic and environmental advantages are foreseen if investments in this area are realized. This Review analyzes and discusses the most recent progress on catalyst technologies, starting from the traditional sulfuric acid process and proceeding to newly emerging catalyst technologies such as solid acid and ionic liquid-based catalysts. We start with basic mechanistic analyses and conclude this Review with the new nonliquid acid-based commercial and emerging technologies for isobutane alkylation. Emphasis is given to the structure−activity relationships and the advantages and disadvantages present in every discussed catalyst material.

H2SO4‐catalyzed isobutane alkylation under low temperatures promoted by long‐alkyl‐chain surfactant additives

“…The isobutane alkylation (C 4 alkylation) with C3 ~ C5 olefins is an important industrial process for the production of the alkylate as an ideal blending component for motor gasoline, due to the dramatic advantages, including no aromatics, free sulfur‐containing components, negligible vapor pressure, high‐octane number, and full combustion 1–3 . Among the alkylate components, TMPs are the most desirable targets with RON more than 100.…”

“…The anionic surfactants amino hydroxynaphthalenedisulfonic acid and naphthalenesulfonic acid were found to enhance TMP content and decrease the heavy ends (HEs) with the optimal addition amount of naphthalenesulfonic acid being 1.0 wt%. More detailed information for the surfactant additives for H 2 SO 4 alkylation is encouraged to read the latest review 2 . Despite the better activity of surfactant additives, the above‐mentioned results still cause many questions due to the lack of a deeper molecular‐level understanding about the effects of surfactants on the acid/C4 hydrocarbons miscibility.…”

Preparation of CuHY catalyst via solid-state ion exchange method and its catalytic performance in isobutane/2-butene alkylation

“…Isobutane/butene alkylation plays a signicant role in the petroleum rening industry because the produced alkylate, which has a high octane number and low contents of sulfur, olen and aromatics, is viewed as an environment-friendly gasoline component. 1 The traditional alkylation processes, including concentrated sulfuric acid alkylation and hydro-uoric acid alkylation, have serious environmental pollution problems and safety risks, which limit their further development and wide application. [2][3][4] Our research group developed a novel composite ionic liquid alkylation (CILA) technique and the rst industrial unit was successfully started up in 2013, however, the spent ionic liquid needs further treatment.…”

Nonsteady-state mathematical modelling of H2SO4-catalysed alkylation of isobutane with alkenes

“…Despite other concerns such as the high operating costs, sulphuric acidcatalyzed processes are less hazardous. Sulfuric acid is also a corrosive liquid, but not so volatile, making its handling easier [14].…”

“…The ASO formation mechanism includes olefin oligomerization, disproportionation and cyclization reactions in acid media [10,15]. Accumulation of too much water causes the deactivation of the moisture-sensitive ionic liquid [14]. Effects of aromatics on ionic liquids for C4 alkylation reaction were discussed in [16].…”