Scaling Parameters for Dynamic Diffusion-Reaction over Porous Catalysts

The effect of diffusion resistance in porous solid catalysts on reaction rate during periodic cycling of CO concentration is shown for CO oxidation over Pt/Al2O3 by numerical simulation. At some cycling frequencies, the average reaction rate during cycling is higher than the steady-state rate at the mean CO concentration, as expected for this nonlinear, reactant-inhibited reaction. In order to identify major aspects of dynamic diffusion-reaction behavior, a simple kinetic mechanism that shows the main features of CO oxidation and other reactions with significant inhibition by reactants is investigated. A single dimensionless parameter group, the dynamic diffusion coefficient, is added when going from steady-state to unsteady-state diffusion-reaction equations. In the dynamic diffusion coefficient, the rate at which the gas-phase reactant diffuses is reduced by the surface adsorption capacity of the catalyst. The frequency at which the peak average rate occurs is controlled by the dynamic diffusion coefficient

A novel carbon-based process for flue gas cleanup

The objective of this project is to demonstrate the preliminary technical and economic feasibility of a novel carbon-based process for removal of at least 95% SO{sub 2} and at least 75% NO{sub x} from coal combustion flue gas. In the process, flue gas leaving the electrostatic precipitator (ESP) is passed through a trickle bed of activated carbon catalyst employing a periodic flush of low strength sulfuric acid. The SO{sub 2} is oxidized to SO{sub 3} and removed as medium strength sulfuric acid. The SO{sub 2}-free flue gas is then mixed with NH{sub 3}, and the NO{sub x} in the gas is subjected to selective catalytic reduction (SCR) to N{sub 2} over a fixed-bed of activated carbon catalyst

A novel carbon-based process for flue gas cleanup. Fifth quarterly technical progress report, July 1--September 30, 1992

The objective of this project is to demonstrate the preliminary technical and economic feasibility of a novel carbon-based process for removal of at least 95% S0{sub 2} and at least 75 % NO{sub x}, from coal combustion flue gas. In the process, flue gas leaving the electrostatic precipitator (ESP) is passed through a trickle bed of activated carbon catalyst employing a periodic flush of low strength sulfuric acid. The S0{sub 2} is oxidized to S0{sub 3} and removed as medium strength sulfuric acid. The S0{sub 2}-free flue gas is then mixed with NH{sub 3}, and the NO{sub x} in the gas is subjected to selective catalytic reduction (SCR) to N{sub 2} over a fixed bed of activated carbon catalyst. In the previous four quarters, a detailed project management plan was prepared describing the experimental setup, work plan, and test plan. The experimental system was completed for SO{sub 2} conversion at Waterloo and for NO{sub x} conversion at Research Triangle Institute. Shakedown experiments were completed. The NO{sub x} removal performance of two additional modified carbon catalysts (MCCII and MCCIII) was studied. MCCII showed NO{sub 2} removal efficiency which was similar to that observed for MCCI. However, MCCIII was considerably less active for NO{sub x} removal. In the present quarter, further tests of MCCI were performed for SO{sub 2} removal with NO in the feed gas, except the reactor was operated at 130{degrees}C (instead of 80{degrees}C during previous tests). Tests were also performed with MCCII for NO removal with nominally 100 ppm SO{sub 2} in the feed gas

A novel carbon-based process for flue gas cleanup. Second quarterly technical progress report, October 1, 1991--December 31, 1991

The objective of this project is to demonstrate the preliminary technical and economic feasibility of a novel carbon-based process for removal of at least 95% SO{sub 2} and at least 75% NO{sub x} from coal combustion flue gas. In the process, flue gas leaving the electrostatic precipitator (ESP) is passed through a trickle bed of activated carbon catalyst employing a periodic flush of low strength sulfuric acid. The SO{sub 2} is oxidized to SO{sub 3} and removed as medium strength sulfuric acid. The SO{sub 2}-free flue gas is then mixed with NH{sub 3}, and the NO{sub x} in the gas is subjected to selective catalytic reduction (SCR) to N{sub 2} over a fixed-bed of activated carbon catalyst

A novel carbon-based process for flue gas cleanup. Third quarterly technical progress report, January 1--March 31, 1992

The objective of this project is to demonstrate the preliminary technical and economic feasibility of a novel carbon-based process for removal of at least 95% SO{sub 2} and at least 75% NO{sub x} coal combustion flue gas. In the process, flue gas leaving the electrostatic precipitator (ESP) is passed through a trickle bed of achieved carbon catalyst employing a periodic flush of low strength sulfuric acid. The SO{sub 2} is oxidized to SO{sub 3} and removed as medium strength sulfuric acid. The SO{sub 2}-free flue gas is then mixed with NH{sub 3}, and the NO{sub x} in the gas is subjected to selective catalytic reduction (SCR) to N{sub 2} over a fixed bed of activated carbon catalyst. The experimental work is divided between Research Triangle Institute (RTI) and the University of Waterloo (Waterloo). RTI will conduct the NO{sub x} removal studies, whereas Waterloo will conduct the SO{sub 2} removal studies. The ultimate goal of the project is to demonstrate that the process can be reduce the cost of electricity by 20% over conventional SCR/flue gas desulfurization (FGD) processes. In the present quarter, the continuous SO{sub 2} analyzer system at Waterloo was completed. The SO{sub 2} removal factorial experiments were begun Waterloo with the BPL carbon at 21{degrees}C. Also, SO{sub 2} removal was tested on two catalyst at RTI at 80{degrees}C. NO{sub x} conversion was tested on a variety of catalysts at RTI. It was shown that the BPL carbon could remove over 95% SO{sub 2} at 21{degrees}C but would required several beds at space velocity in each bed of abut 1,500 scc/(cc{center_dot}h) to reduce SO{sub 2} from 2,500 ppm to 100 ppm. A modified carbon catalyst tested at RTI showed 99% SO{sub 2} removal at 80{degrees}C at 1,400 scc/(cc{center_dot}h). Also, it was possible to produce nearly 9 normal H{sub 2}SO{sub 4} by periodic flushing of this catalyst. The modified carbon catalyst also demonstrated removal of more than 80% NO{sub x}. 7 refs., 7 figs., 4 tabs

A novel carbon-based process for flue gas cleanup

The objective of this project is to demonstrate the preliminary technical and economic feasibility of a novel carbon-based process for removal of at least 95% S0[sub 2] and at least 75 % NO[sub x], from coal combustion flue gas. In the process, flue gas leaving the electrostatic precipitator (ESP) is passed through a trickle bed of activated carbon catalyst employing a periodic flush of low strength sulfuric acid. The S0[sub 2] is oxidized to S0[sub 3] and removed as medium strength sulfuric acid. The S0[sub 2]-free flue gas is then mixed with NH[sub 3], and the NO[sub x] in the gas is subjected to selective catalytic reduction (SCR) to N[sub 2] over a fixed bed of activated carbon catalyst. In the previous four quarters, a detailed project management plan was prepared describing the experimental setup, work plan, and test plan. The experimental system was completed for SO[sub 2] conversion at Waterloo and for NO[sub x] conversion at Research Triangle Institute. Shakedown experiments were completed. The NO[sub x] removal performance of two additional modified carbon catalysts (MCCII and MCCIII) was studied. MCCII showed NO[sub 2] removal efficiency which was similar to that observed for MCCI. However, MCCIII was considerably less active for NO[sub x] removal. In the present quarter, further tests of MCCI were performed for SO[sub 2] removal with NO in the feed gas, except the reactor was operated at 130[degrees]C (instead of 80[degrees]C during previous tests). Tests were also performed with MCCII for NO removal with nominally 100 ppm SO[sub 2] in the feed gas

A novel carbon-based process for flue gas cleanup

The objective of this project is to demonstrate the preliminary technical and economic feasibility of a novel carbon-based process for removal of at least 95 % SO[sub 2], and at least 75 % NO[sub x] from coal combustion flue gas. In the process, flue gas leaving the electrostatic precipitator (ESP) is passed through a trickle bed of activated carbon catalyst employing a periodic flush of low strength sulfuric acid. The SO[sub 2] is oxidized to SO[sub 3] and removed as medium strength sulfuric acid. The SO[sub 2]-free flue gas is then mixed with NH[sub 3], and the NO[sub x] in the gas is subjected to selective catalytic reduction (SCR) to N[sub 2] over a fixed bed of activated carbon catalyst. In the previous six quarters, detailed project plans were prepared and experimental systems were commissioned. The SO[sub 2] removal factorial experiments with BPL carbon at 21[degrees]C are well underway at Waterloo. A modified carbon catalyst (MCCI) showed up to 99% SO[sub 2] removal in the presence of NO[sub x] over 10 multiple cycles at 80--130[degrees]C and 1400 scc/cc/h. Several catalysts were evaluated for NO[sub x] removal also. Promising modified carbon catalysts (MCCI, II and III) were tested. Some of these catalysts showed the potentialfor over 80% NO[sub x] removal at space velocities as high as 3000 scc/cc/h. Poisoning of NO[sub x] removal efficiency with SO[sub 2] in the feed was also studied. With over 100 ppm SO[sub 2] in feed, NO[sub x]removal efficiency remained steady for several hours. It declined from 79% removal to 66% removal over 24 hours. NO[sub x] removal experiments were performed with 5 different materials and the SO[sub 2] removalactivity of 2 catalysts was tested