Sweetening of straight-run gasoline and kerosene: The classical catalytic desulfurization (non-hydrogen) “clay treating/sweetening” step commonly utilizes which type of solid as the catalytic medium?

Introduction / Context:“Sweetening” of light distillates (straight-run gasoline and kerosene) traditionally refers to oxidation or adsorption treatments that reduce odor and corrosivity by converting or removing mercaptans and color bodies without high-pressure hydrogen. Clay and earth materials have long been used in such catalytic/adsorptive polishing steps.

Given Data / Assumptions:

• Process is a classical (non-H2) sweetening/polishing of light streams.
• Materials considered: bauxite, Fuller’s earth, and activated clay.
• Goal: improve odor/color, reduce mercaptans/gums.

Concept / Approach:Acidic clays and naturally occurring aluminosilicates provide mild catalytic activity and significant adsorption capacity. They catalyze oxidation/polymerization of trace unsaturates and facilitate removal of mercaptans and color precursors, thereby “sweetening” the product. All listed minerals have been used historically in such services.

Step-by-Step Solution:Identify conventional sweetening medium → acid clays and bauxite.Role → catalyze mild reactions and adsorb contaminants.All three listed media qualify in practice for straight-run gasoline/kerosene sweetening.Thus, choose “All of the above”.

Verification / Alternative check:Refinery handbooks describe clay treating towers/filters using bauxite, Fuller’s earth, or activated clays for color/mercaptan reduction prior to modern hydrotreating ubiquity.

Why Other Options Are Wrong:

• Each individual medium (A, B, C) is valid, but the question seeks the general class; hence “All of the above”.
• Co-Mo/Al2O3 is a hydrotreating catalyst used under hydrogen pressure, which is a different process route than classical clay sweetening.

Common Pitfalls:Conflating clay sweetening with hydrotreating; they target similar contaminants but employ very different operating conditions and catalysts.

Final Answer:All of the above