Apparent kinetics of the catalyzed water–gas shift reaction in synthetic wood gas

• Empirical power law rate models of two commercial WGS catalysts are established.
• The feed simulates the wood gas derived from the DFB steam gasification of biomass.
• Apparent reaction orders are estimated in the presence of hydrogen sulfide.
• Sulfur doubles the activity of catalyst 1 and reduces by 50% the activity of cat.2.
• From a certain temperature the activity of catalyst 1 is not influenced by sulfur.

The catalysis of the water–gas shift reaction employing two commercially available catalysts was investigated. The applied feed was a synthetic gas mixture simulating the wood gas derived from the dual fluidized bed steam gasification of biomass. A Co/Mo- and an Fe/Cr-based catalyst were compared in a differentially operated plug flow reactor. The influence of the partial pressures of all reaction partners as well as the effect of temperature were studied, allowing the formation of two power law rate models.equation(1)r(Co/Mo)=0.044exp-66RTpCO1.28pH2O0.03pCO2-0.11pH2-0.351-1KpCO2pH2pCOpH2Oequation(2)r(Fe/Cr)=300exp-102RTpCO1.37pH2O0.23pCO2-0.16pH2-0.111-1KpCO2pH2pCOpH2OThe CO conversion rates over both catalysts were strongly dependent on the sulfur load in the feed. The presented models were established at a constant H2S concentration of 100 vol.ppmdb. At this sulfur load the Fe/Cr-based catalyst should be preferred to the Co/Mo-based catalyst. The partial pressure of H2S could not be included in the power law models because of its influence on the other coefficients of the model.

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