Named reactor hardware:\nThe Fauser–Montecatini converter is historically associated with which unit operation in a nitrogen fertilizer complex?

Introduction / Context:
Legacy plant equipment often carries the names of developers or licensors. The Fauser–Montecatini converter is a classic high-pressure ammonia synthesis reactor design from early generations of Haber–Bosch technology. Recognizing which step it belongs to helps interpret historical plant diagrams and exam questions that reference vintage hardware.

Given Data / Assumptions:

• Fauser and Montecatini were Italian innovators in ammonia technology.
• “Converter” in nitrogen plants generally denotes the ammonia synthesis reactor.
• Other units (shift, methanation, reforming) have distinct equipment names.

Concept / Approach:
The ammonia converter is the fixed-bed catalytic reactor where N2 and H2 produce NH3 at elevated pressure and moderate temperature, using promoted iron catalysts. The Fauser–Montecatini design relates to this synthesis step rather than upstream gas conditioning (shift or methanation) or secondary reforming, which are separate reactors with different internals and catalysts.

Step-by-Step Solution:
Identify the historical association: Fauser–Montecatini with ammonia synthesis.Differentiate from shift (Fe/Cr), methanation (Ni), and reforming (Ni) reactors.Select “Ammonia synthesis (high-pressure converter)”.

Verification / Alternative check:
Historical references to plants such as FCI Sindri cite Fauser–Montecatini high-pressure converters in the NH3 loop, confirming the association.

Why Other Options Are Wrong:
Methanation and shift use different catalysts and reactor styles; secondary reformers are fired reactors combining air addition with catalytic beds—distinct from the ammonia loop converter.

Common Pitfalls:
Assuming “converter” generically applies to any catalytic reactor; in NH3 plant jargon, it typically points to the synthesis loop reactor.

Final Answer:
Ammonia synthesis (high-pressure converter)