Solid acid catalysts in heterogeneous n-alkanes hydroisomerisation for increasing octane number of gasoline

Abstract

As the current global environmental concerns have prompted regulations to reduce the level of aromatic compounds, particularly benzene and its derivatives in gasoline, hydroisomerisation of n-alkanes is becoming a major alternative for enhancing octane number. Series of solid acid catalysts comprising of Freidel crafts, zirconias, MoO3-based (MOB), chlorinated Al2O3, heteropoly acids and bifunctional zeolite based catalysts have been tested in this respect. This paper reviewed important studies conducted on these catalysts with the aim of identifying areas requiring further investigation(s). Freidel craft catalysts are currently abandoned due to corrosion and disposal problems. MOB and heteropoly acids have good resistance to nitrogen and sulphur in a reaction stream but have poor thermal stability, difficult to regenerate and with mechanism their action only partly resolved. Bifunctional zeolites on the other hand are increasingly becoming promising catalysts due to resulting high acidity, activity and easy regeneration properties. Both solid and gaseous acid modifiers could similarly modify their textural characteristics. The activities of all catalysts could under uncontrolled conditions lead to side reactions such as cracking, aromatisation and dehydrogenation.

Acid Strength of Pt-Zeolite Catalysts: Evidence of Metal-Support Interaction from Linear Free-Energy Relationship

“…Bifunctional metal-zeolite catalysts are widely used in hydroisomerization and hydrocracking of hydrocarbons [1]. The metal function acts as dehydrogenating/hydrogenating site, whereas the acid function catalyzes branching and b-scission reactions, which normally involves carbocation intermediates.…”

In situ fast pyrolysis of biomass with zeolite catalysts for bioaromatics/gasoline production: A review

“…Brønsted acid sites are more likely to participate in the fast pyrolysis of biomass due to the nature of the various intermediate reactions involved. These acid sites have been previously shown to be active for the conversion of methanol to olefins and for gasoline transformations [161][162][163][164]; hydrocracking/cracking of naphtha [165,166], isomerization [167,168], polymerization [169,170], alkylation [106,171], aromatization [172,173] and other reactions involving C-O and C-C bonds cleavages. All of these reactions have been observed to occur during pyrolytic biomass-upgrades [174].…”

Catalytic Activity of a Bifunctional Catalyst for Hydrotreatment of Jatropha curcas L. Seed Oil

“…In fact, new research materials focus on improving catalytic activity and generate fewer by-products and contaminants [3]. The heterogeneous catalyst is the great economic impact as the USY zeolite which provides high activity and selectivity of the catalysts.…”