Ammonia synthesis gas from solid fuels:\nLow-grade coal is primarily ________ to generate hydrogen-rich synthesis gas for the ammonia (Haber–Bosch) loop.

Introduction / Context:
Modern ammonia plants need a reliable source of hydrogen to combine with nitrogen in the Haber–Bosch synthesis loop. While natural-gas-based plants obtain hydrogen by steam reforming, coal-rich regions often rely on coal gasification to make synthesis gas (CO and H2), which is then conditioned into an ammonia-suitable feed. Understanding the front-end conversion step for low-grade coal is foundational in fertilizer technology and energy chemistry.

Given Data / Assumptions:

• The feedstock is low-grade coal (lignite/sub-bituminous), not natural gas or naphtha.
• Target is ammonia synthesis gas with high H2 and appropriate N2 downstream.
• We need the primary chemical conversion step applied to coal in such complexes.

Concept / Approach:
Coal cannot be “reformed” the way methane is; instead, it is reacted with oxygen and steam at high temperature and pressure to form syngas. The core step is gasification, which produces a mixture of CO, H2, CO2, H2O, and impurities (H2S, COS, tars) that must be cleaned. Subsequent water–gas shift converts CO + H2O to CO2 + H2, after which CO2 is removed and nitrogen is supplied (via air separation) for the Haber–Bosch loop.

Step-by-Step Solution:
Feed coal to an entrained- or fixed-bed gasifier with O2 and steam → generate CO + H2 (syngas) plus impurities.Condition syngas: dust removal, tar cracking (if needed), desulfurization (H2S removal).Apply shift reaction: CO + H2O → CO2 + H2 to raise hydrogen content.Remove CO2 and trace contaminants; add N2 from ASU; compress and feed to Haber–Bosch.

Verification / Alternative check:
Process flow diagrams of coal-based ammonia/urea complexes consistently show gasifiers, shift converters, CO2 removal, and an ammonia synthesis loop. None of the alternatives (liquefaction, dehydrogenation) alone produce the required H2-rich syngas for ammonia.

Why Other Options Are Wrong:
Hydrogenation and dehydrogenation describe different chemistries not used to convert solid coal into H2; liquefaction produces liquid hydrocarbons, not syngas; “partial nitration” is unrelated to syngas production.

Common Pitfalls:
Assuming the same “reforming” vocabulary applies to coal and methane; coal needs gasification, not catalytic steam reforming of a gas.

Final Answer:
gasified