Dewaxing of petroleum products: Which of the following are common solvents used specifically for solvent dewaxing?

Introduction:
Dewaxing removes high-melting waxes from lubricating oil stocks and other petroleum fractions to improve low-temperature flow properties such as pour point.

Given Data / Assumptions:

• We focus on solvents used in the dewaxing step.
• Common industrial choices include ketone-based and hydrocarbon/propane systems.

Concept / Approach:
Solvent dewaxing relies on selective dissolution at low temperatures to precipitate wax. MEK (often with toluene or MIBK) and liquid propane are widely used. Furfural is a selective extraction solvent for aromatics, not a dewaxing solvent.

Step-by-Step Solution:

Verification / Alternative check:
Process flow descriptions pair MEK with a co-solvent (often toluene) and also describe propane dewaxing units.

Why Other Options Are Wrong:

• Furfural: Extraction solvent, not for dewaxing.
• Toluene only: Common co-solvent with MEK, rarely used alone as the primary dewaxing solvent.

Common Pitfalls:
Confusing extraction (furfural) with dewaxing; overlooking propane-based dewaxing.

Final Answer:
Both (b) and (c)