Chromium-free shift catalysts

The simplest solution to this problem is to modify the classic iron-based HTS catalyst by adding a moderate amount of copper to reduce the amounts of byproducts formed and to give a much higher catalyst activity for the shift reaction. A second and more radical solution, is the use of an iron-and chromium-free HTS catalyst that is copper-based73. 

HTS catalyst consists mainly of magnetite crystals stabilized using chromium oxide. Phosphoms, arsenic, and sulfur are poisons to the catalyst. Low reformer steam to carbon ratios give rise to conditions favoring the formation of iron carbides which catalyze the synthesis of hydrocarbons by the Fisher-Tropsch reaction. Modified iron and iron-free HTS catalysts have been developed to avoid these problems (49,50) and allow operation at steam to carbon ratios as low as 2.7. Kinetic and equiUbrium data for the water gas shift reaction are available in reference 51. 

S. Natesakhawat, X. Wang, L. Zhang, U. S. Ozkan, Development of chromium-free iron-based catalysts for high-temperature water-gas shift reaction, J. Mol. Catal. A Chem. 260 (2006) 82-94. 

F. Meshkani, M. Rezaei, Mesoporous Ba-promoted chromium free Fe2Q3-Al203-Ni0 catalyst with low methanation activity for high temperature water gas shift reaction, Catal. Commun. 58 (2015) 26-29. 

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