The properties of dried (but not calcined) coprecipitated nickel ceria systems have been investigated in terms of their hydrogen emission characteristics following activation in hydrogen. XRD and BET data obtained on the powders show similarities to calcined ceria but it is likely that the majority of the material produced by the coprecipitation process is largely of an amorphous nature. XPS data indicate very little nickel is present on the outermost surface of the particles. Nevertheless, the thermal analytical techniques (TGA, DSC and TPD-MS) indicate that the hydrogen has access to the catalyst present and the nickel is able to generate hydrogen species capable of interacting with the support. Both unactivated and activated materials show two hydrogen emission features, viz. low temperature and high temperature emissions (LTE and HTE, respectively) over the temperature range 50 and 500 degrees C. A clear effect of hydrogen interaction with the material is that the activated sample not only emits much more hydrogen than the corresponding unactivated one but also at lower temperatures. H(2) dissociation occurs on the reduced catalyst surface and the spillover mechanism transfers this active hydrogen into the ceria, possibly via the formation and migration of OH(-) species. The amount of hydrogen obtained (~0.24 wt%) is approximately 10x higher than those observed for calcined materials and would suggest that the amorphous phase plays a critical role in this process. The affiliated emissions of CO and CO(2) with that of the HTE hydrogen (and consumption of water) strongly suggests a proportion of the hydrogen emission at this point arises from the water gas shift type reaction. It has not been possible from the present data to delineate between the various hydrogen storage mechanisms reported for ceria.
Mercury is present as elemental mercury in natural gas reservoirs and has to be removed in the natural gas processing plants to protect health, environment and equipment. The mercury removal options are mainly non-regenerative products. The adsorption mechanism is a chemical reaction between mercury and the sulfur of the active phase to form non-hazardous and very stable cinnabar phase.The trend is to implement mercury removal vessels the closest to the production wells to minimize mercury contaminations in natural gas plants. This up-front location implies adsorbents able to remove mercury from high operating pressure water saturated natural gas. Metal sulphide active phase adsorbents have been developed for this purpose. This paper will present examples of commercial application with existing mercury removal solutions to illustrate the benefits available from use of the new technology focused on engineered alumina based products. A case study based on performances comparison with different solutions at up-front locations will be presented.
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