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[Art Montemayor]

ahboon:

The catalytic hydrogenation of gases containing a maximum content of 2 % carbon oxides is an important step in the production of pure Hydrogen via the Steam Reforming Process. It is a very strong exothermic process that takes place usually in a single bed of 25% Nickel catalyst that is in 1/4" cylindrical form. The reactor is usually a vertical cylindrical pressure vessel that contains the fixed bed of catalyst and the reaction takes place under adiabatic conditions. Since the reaction is an exotherm with total reliance on the products for heat removal, care must be exercised to not allow a runaway reaction.

The feed gas must be devoid of any sulfur compounds, since these are catalyst poisons. A hot zinc oxide reaction usually precedes the methanation step if sulfur is a problem.

Read "Gas Purification" by Kohl & Riesenfeld, a chemical engineering classic to get more details. In case you don't have access to this book, the following are some reactor typical operating data:

Inlet temp = 500 oF
Outlet temp = 550 oF
Pressure = 750 psig
Space Velocity = 1,000 vol/vol-hr

Hope this answers all your questions.