What is the effect of CO on hydrogenation catalysts?

1. If the hydrogenation catalyst is of the CO-MO series, then under the action of nickel- or cobalt-based catalysts, carbon monoxide and carbon dioxide react with hydrogen at temperatures between 200°C and 350°C to produce methane, while releasing a large amount of heat. The heat generated by the methanation reaction causes the catalyst bed in the reactor to heat up excessively, resulting in an uneven temperature distribution and deteriorating the operation of the facility. 2. Carbon monoxide, carbon dioxide, and hydrogen compete for adsorption at the active sites of the catalyst, affecting the utilization of the hydrogenation active sites. Carbon monoxide may form toxic, volatile carbonyl compounds with the metal components on the catalyst, causing corrosion of the catalyst and reducing its activity. 4n6R1`/s$i:]#y3u 50℃ 230℃0Q/E3T7e;k 4CO+Ni Ni(CO)4 Ni+4CO3V&f6~-@ i2j1V(k Since the aforementioned reactions occur more easily at low temperatures, the catalyst’s activity is reduced each time it is put into use when carbon monoxide is present in the circulating hydrogen. At low temperatures, carbon monoxide reacts with the nickel component on the catalyst to form nickel carbonyl; when the temperature rises, nickel carbonyl volatilizes and sublimates, exposing metallic nickel on the surface of the catalyst. Metallic nickel has a very high hydrogenolysis activity, which can easily lead to coking and deactivation. When CO in hydrogen exceeds 100 ppm, the monthly loss of activity is 2℃ ； Above 1000 ppm, the monthly loss of activity is above 6°C. Topson Company does not recommend keeping the CO content in the new hydrogen above 10 ppm

There is primarily a methanation reaction, and this reaction is also exothermic! It affects the temperature of the catalyst bed, and can even lead to overheating, thereby impacting the catalyst’s activity

Nickel hydroxide also reacts only at low temperatures, and the methanation reaction occurs only at 200°C–350°C. Normally, hydrogenation is carried out at temperatures above 350°C; so what impact can this have on the catalyst?

It depends on what kind of catalyst it is in what device.

This post was last edited by zls1457 on 2017-3-27 at 11:28; personal understanding； Carbon monoxide is generally present in the fresh hydrogen; it primarily undergoes methanation reactions in the reactor, which are exothermic reactions. This can lead to fluctuations in the temperature of the reactor bed, as well as fluctuations in the pressure of the reactor bed. The second methanation reaction may affect the mechanical strength of the catalyst carrier. It’s purely my personal understanding.

The main purpose is to prevent methanation reactions from occurring, which would generate a large amount of heat and lead to overheating of the bed. Therefore, it is necessary to strictly control the CO content in the fresh hydrogen; this CO content serves as an important parameter in the analysis of fresh hydrogen (usually ≤20 ppm). The impact on the purity of the recycled hydrogen is secondary, as there are many factors that can affect its purity