MechChem Africa January-February 2021

⎪ Manufacturing and food processing ⎪

A nitrogen molecule (N 2 ) first breaks away, leaving only the oxygen atom chemically bonded to the catalyst’s surface. The oxygen atom quickly combines with another oxygen atom and leaves the surface as an oxygen molecule (1) or if the reaction is carried out in the presence of a reducing agent, a water moleculeisformed(2).Commonlyusedreduc- ing agents include ammonia, methane, ethane and propane. 1. 2N 2 O → 2N 2 + O 2 2. N 2 O + reducing agent → 2N 2 + H 2 O South African environmental legislation Compared to many other countries, legal specifications in South Africa for nitrogen oxide emissions are relatively relaxed (Table 1). Major South African nitric acid producers, such as Omnia, are using EnviCat ® to meet their own emission targets, which can go far beyond current legislation. In thisway, a local- lymanufacturedcatalysthelpsmanydomestic companies to reduce their environmental impactandtheircontributiontowardsclimate change. In conclusion, while the quantity of nitrousoxidesemittedbyindustryisrelatively small compared to CO 2 emissions, N 2 O has a markedly greater greenhouse gas effect by virtueof itsmuch longer lifetime in the earth’s atmosphere.While nitric acid production can

Figure 2: Clariant’s EnviCat ® catalyst is produced in Richards Bay

leading and proven solution for the industrial abatement of the emissions of this very high GWP gas . q

create significant N 2 O emissions, Clariant’s innovative EnviCat ® catalyst – a proudly South African manufactured product – is a

Table 1: The minimum emission standards for nitric acid production in South Africa compared to the emissions that can be achieved when using EnviCat.

Subcategory 7.2: Primary production of acids: The primary production of nitric acid with concentrations exceeding 10 % Current specifications: Oxides of nitrogen expressed as NOx (mg/Nm 3 under normal conditions of 6 % O2, 273 K and 101.3 kPa) Achieved with EnviCat: Oxides of nitrogen expressed as NOx(mg/Nm 3 under normal conditions of 6 % O2, 273 K and 101.3 kPa)


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January-February 2021 • MechChem Africa ¦ 35

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