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Chapter 11Production of HNO 3 : De-N 2 O catalysts and techniquesTwo approaches have been realised in existing plants to reduce the N 2 O emissions from nitricacid production:1. catalytic decomposition of N 2 O in the reactor chamber (see Section 3.4.6) and2. combined catalytic abatement of N 2 O and NO x applied to the tail gas (see Section 3.4.7).A modified combined catalytic treatment applied to the tail gas is shown in Section 3.6.1 as anemerging technique. However, no new plant has been yet equipped with any of these catalyticDe-N 2 O technologies. Future work could present and build on the experience gained from theimplementation of these techniques in current projects, projects triggered by the conclusions inSection 3.5, CDM or JI projects.Improved SCR catalystThe technique shown in Section 3.4.7 also offers selective catalytic reduction of NO x to verylow NO x levels and with practically zero NH 3 slip. Future work could assess to which extentthis performance can be transferred to other SCR systems. This would represent a majorachievement.Abatement/recovery of NO x if SNCR or SCR are not applicableAs an example, Section 1.4.7 presents a technique to recover NO x from exhaust gases based onscrubbing. Future work could assess the technical and economic viability of recovering NO xfrom exhaust gas, e.g. from strong NO x sources, such as the digestion of phosphate rock withHNO 3 (see, e.g. Section 7.4.9 and the related BAT in Section 7.5).RTD programmes launched by the ECThe EC is launching and supporting, through its RTD programmes, a series of projects dealingwith clean technologies, emerging effluent treatment and recycling technologies andmanagement strategies. Potentially these projects could provide a useful contribution to futureBREF reviews. Readers are therefore invited to inform the EIPPCB of any research resultswhich are relevant to the scope of this document (see also the preface of this document).Large Volume Inorganic Chemicals – Ammonia, Acids and Fertilisers 401