Low Temperature Carbon Monoxide Conversion

As the industry moved towards eleaner feedstocks, such as naphtha and naturals gas, and the rrse of increasingly effiderrt gas purification systems, the synthesis 

It is important to understand the coimnercial significance of an active catalyst which can operate at maximum conversion for long, predictable periods in large anunonia plants. In a typical 1000 toimes per day ammonia plant the most obvious penally is the daily cost of an imexpected plant closure. Anther less obvious cost is the overall effeet of an increase in the volume of earbon monoxide leaving the low temperature reactor. One volume of hydrogen is lost for every 

Every catalyst in an ammonia plant is important but, because low-temperature carbon monoxide conversion catalyst is likely to be the most sensitive to poisons, good operation of this catalyst is probably the most significant. Apart from using the best available catalyst, it is usual to make an allowance for catalyst poisoning by increasing the catalyst volmne in the reactor. 

An LTS catalyst should be sufficiently active to give a high conversion for a given volume of catalyst at the minimum practicable temperature. It should also be thermally stable and operate for the design period with maximum carbon monoxide conversion. With proper design and good upstream poisons removal, a typical catalyst lifetime is about three years. 

Most spent catalysts contain varying amounts of sulfur, chlorine and siUca poisons depending on the age of the catalyst and the purity of synthesis The effects of each poison can therefore be considered separately in relation to the differing operating conditions. In some cases, up to 3-4% sulfur has been meas- 

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