Isobutane/butene alkylation reaction using ionic liquids as catalysts. Toward a sustainable industry

• Conventional catalysts in the gasoline production process are toxic and corrosive. • It has been demonstrated that ionic liquids can catalyze the alkylation reaction. • Ionic liquids with Brønsted and Lewis acid sites have high performance and stability. • Composite ionic liquids have demonstrated high efficiency on an industrial scale. The isobutane/butene alkylation reaction is one of the most crucial refining processes since it gives rise to high octane and high purity gasoline, one of the main contributors to the gasoline pool. Conventionally, the alkylation reaction is carried out industrially using hydrofluoric and sulfuric acids, which have significant safety, corrosivity, recyclability, and sustainability concerns, making the development of efficient, environmentally friendly, and sustainable catalysts for this reaction an active research topic. Due to their attractive physicochemical properties, ionic liquids seem to be the most promising alternative to replace the catalysts commonly used at the industrial level. The present compendium reviews research works to develop ionic liquids as catalysts of the isobutane/butane reaction to obtain a more efficient, sustainable, and environmentally friendly process. These compounds can mitigate the environmental problems associated with inorganic acids that have been used for many years as catalysts of this reaction on an industrial scale. The most recent articles and patents dealing with the advances in the alkylation reaction employing commercial technologies to obtain alkylated gasoline based on ionic-liquid catalysts, which have not been featured in previous reviews, are emphasized and discussed here.