Ostwald Process\nIntensification by Catalytic Oxidation\nof Nitric Oxide

The Ostwald process is one of the commercial pathways\nfor the production\nof nitric acid (HNO<sub>3</sub>), a key component in the production\nof nitrate fertilizers. The Ostwald process is a mature, extensively\nstudied, and highly optimized process, and there is still room for\nfurther intensification. The process can be further intensified by\ncatalyzing the homogeneous oxidation of nitric oxide to nitrogen dioxide.\nIn this work, we explore the NO to NO<sub>2</sub> oxidation capacity\nof ruthenium on γ-Al<sub>2</sub>O<sub>3</sub> support wash-coated\non to a cordierite monolith. In a lab-scale setup with simulated feed\ncomprising 10% NO, 6% O<sub>2</sub>, 15% H<sub>2</sub>O and rest Ar,\nand 8% NO, 2% NO<sub>2</sub> 5% O<sub>2</sub>, 15% H<sub>2</sub>O\nand rest Ar, the ruthenium and γ-Al<sub>2</sub>O<sub>3</sub> wash-coated monoliths attained a steady conversion of 72 and 56%,\nrespectively. A remarkable steady conversion of 20% more than the\ngas phase for 65 h over 4 days was presented by the Ru<sub>Wc,γ–Al<sub>2</sub>O<sub>3</sub>,Cordierite</sub> catalyst in one of the pilot\nplants at Yara, a Norwegian fertilizer company. The results presented\nin this work clearly provide evidence to support the idea that ruthenium\non a gamma-alumina catalyst support can oxidize NO to NO<sub>2</sub> under industrial nitric acid production conditions and mark an important\nstep in the intensification of the Ostwald process.