Industrial sources of NOx — identify where it is not produced Among the following industries, where is nitrogen oxides (NOx) not a typical process emission?

Introduction / Context: Nitrogen oxides (NO and NO2, collectively NOx) are produced in high-temperature combustion and in specific nitrogen-processing chemical operations. Identifying typical sources is fundamental to air-pollution control planning.

Given Data / Assumptions:

• Nitric acid manufacture intentionally oxidizes ammonia, forming NOx intermediates.
• Nitrogenous fertilizer production often integrates nitric acid or ammonia oxidation steps.
• Detergent manufacturing primarily involves surfactant chemistry without NOx-forming oxidation stages.

Concept / Approach: NOx is an intrinsic by-product in nitric acid plants (e.g., tail gas) and can be associated with fertilizer processes that use or make nitric acid. In contrast, detergent plants are not primary NOx process sources, aside from general combustion emissions (e.g., steam boilers), which are not the core process emissions the question targets.

Step-by-Step Solution:

Verification / Alternative check: Emission inventories list nitric acid plants as classic NOx sources; detergent plants typically control VOCs and particulate from powders, not NOx process emissions.

Why Other Options Are Wrong:

Common Pitfalls: Confusing general utility boilers (which can emit NOx) with the core chemical process emissions referenced in such questions.

Final Answer: detergent