In industrial chemistry, “synthesis gas” (syngas) is a fuel-gas mixture used for chemical synthesis. Which single component is an essential constituent present in all synthesis gas formulations?

Introduction / Context:
Synthesis gas, commonly called syngas, is the foundational feed for several cornerstone processes such as ammonia, methanol, oxo-synthesis, and Fischer–Tropsch conversions. While exact compositions vary by final product and production route, a unifying feature is the presence of hydrogen, which participates directly in hydrogenation and reduction reactions central to these syntheses.

Given Data / Assumptions:

• Syngas refers to process gas produced by reforming, gasification, or partial oxidation, tailored for downstream synthesis.
• Typical constituents considered: H2, CO, CO2, steam, and sometimes N2 as diluent; O2 is not a constituent of the product syngas stream.
• The question asks for an essential constituent across all practical formulations.

Concept / Approach:
Most synthetic routes require hydrogen either as a direct reactant (e.g., methanol from CO/CO2 + H2; hydrocarbon chains from CO + H2) or as the entire reductant in ammonia manufacture (after removing CO/CO2 and adding N2). Therefore, H2 is the common denominator. CO, while very common in syngas for methanol or Fischer–Tropsch, is not required for ammonia syngas, which is essentially H2 + N2 after CO cleanup.

Step-by-Step Solution:
Identify key syntheses using syngas: methanol (needs H2), Fischer–Tropsch (needs H2), ammonia (needs H2).Compare compositions: ammonia “syngas” contains H2 + N2 with CO minimized to trace; methanol/F–T syngas contains CO + H2.Determine universal constituent: H2 is present in all cases, whereas CO is absent in ammonia make-up gas.Conclude that hydrogen is the essential component across all syngas applications.

Verification / Alternative check:
Process block diagrams show reforming/gasification produce CO + H2; ammonia trains include shift, CO2 removal, and methanation to strip CO/CO2, leaving H2 for synthesis with N2. Methanol/F–T retain CO with H2, again requiring H2.

Why Other Options Are Wrong:
O2: syngas is produced in oxygen-limited environments and O2 is not a product constituent.CO2: may be present but is typically removed or minimized for most syntheses.N2: essential only for ammonia; not required for methanol or Fischer–Tropsch.

Common Pitfalls:
Assuming CO is universal because many texts define syngas as CO + H2; forgetting that ammonia process gas is H2-rich with CO driven to near zero.

Final Answer:
H2