Solvent deasphalting (SDA): Which solvent is industrially used to deasphalt vacuum residue in propane deasphalting units?

Introduction / Context:Solvent deasphalting separates heavy vacuum residue into a deasphalted oil (DAO) and an asphaltene-rich pitch. The choice of solvent controls selectivity, product quality, and yield.

Given Data / Assumptions:

• Target: remove asphaltenes/metals to produce DAO for FCC/hydrocracking.
• Common SDA solvents: light paraffins (C3–C5), most notably propane.
• Operation under elevated pressure to maintain solvent in liquid phase.

Concept / Approach:Propane selectively dissolves maltenes while precipitating asphaltenes. Adjusting temperature/solvent ratio tunes DAO quality (metals, CCR) and yield. Heavier paraffins like butane/pentane increase DAO yield but reduce rejection severity.

Step-by-Step Solution:Identify SDA solvent class → light paraffin hydrocarbons.Propane is the classical choice → “propane deasphalting”.Therefore, select Propane.

Verification / Alternative check:Standard refinery texts reference propane/butane SDA units, with “PDA” widely implemented for residue upgrading.

Why Other Options Are Wrong:

• Furfural/phenol: used in lube solvent extraction, not SDA.
• Hexane: not the standard SDA solvent; paraffins C3–C5 are preferred.
• Acetone: not used for SDA.

Common Pitfalls:Confusing lube extraction solvents with SDA solvents; the objectives and selectivities differ.

Final Answer:Propane