A thorough and comprehensive study of different parameters affecting the sorbents prepared by impregnating polyethyleneimine (PEI) on silica for CO 2 capture has been conducted. The CO 2 capture performances of resulting sorbents were evaluated on both packed-bed and fluidized-bed reactors. Obtained results indicated that CO 2 adsorptiondesorption performances of sorbents are greatly affected by the operation temperature in both simulated flue gas from coal fired power plant (SCF) and natural gas combined cycle power plant (NGCC). The optimal adsorption temperatures are from 50 to 80 o C for NGCC flue gas and from 70 to 90 o C for SCF flue gas, while the optimal regeneration temperatures are from 110 to 130 o C for both flue gas. Adsorbent containing 30 to 35 wt% PEI fluidized well with both simulated flue gas and steam. Results from this study revealed that PEI impregnated silica is a promising sorbents for CO 2 capture process, using a fluidized-bed reactor, from both coal-fired power and natural gas combined cycle power plants.
The production of hydrogen from renewable and nonrenewable resources is demonstrated. Catalytic steam reforming, using a rhodium-containing catalyst, is shown to be effective for the conversion of natural gas and n-hexadecane (used as a simulant for diesel fuel). Improved conversion efficiencies can be achieved by performing the reaction at higher temperatures and steam to carbon ratios. The presence of sulfur in the fuel is shown to have a significant inhibiting effect on catalyst performance. Steam reforming of biomass-derived species is less effective when compared with that of simpler compounds such as methane and methanol, because these species decompose to produce tars and chars at temperatures below which steam reforming reactions are effective. Autothermal reforming has been shown to be relatively effective for several biomass-derived species.
Production of hydrogen from natural gas is the most cost-effective and simplest technology for commercial hydrogen generation. Natural gas is also a likely source of hydrogen for residential fuel cell systems, due to its wide availability and ease of conversion via steam methane reforming. Although catalyst technology is available for generating hydrogen from natural gas, the design of new catalysts and new catalytic supports to overcome the limitations associated with ceramic catalyst provides an opportunity to make the conversion of natural gas to hydrogen more cost-effective. In the present study, the performance of Ni-Rh/Al 2 O 3 -CeO 2 -ZrO 2 , Ni-Rh/γ-Al 2 O 3 , and Ni-Pd/γ-Al 2 O 3 catalysts were quantitatively evaluated in terms of activity and stability using appropriate kinetic models. Catalysts were tested as powders and supported on metal foil. Results proved rhodium to be a better active agent than palladium, and catalyst activity was found to increase with the increase in rhodium loading at both atmospheric and elevated pressures. γ-Al 2 O 3 supported rhodium catalysts exhibited a better performance at a much lower rhodium loading than the Al 2 O 3 -CeO 2 -ZrO 2 supported catalysts. Mass and heat transfer advantages of the metallic support over the powder form were also established by studying the performance of this catalyst in both forms to demonstrate the potential for the use of metal structured support to achieve commercially relevant hydrogen production targets at lower residence times.
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