CO REMOVAL

Chemical Conversion. In both on-site and merchant air separation plants, special provisions must be made to remove certain impurities. The main impurity of this type is carbon monoxide, CO, which is difficult to separate from nitrogen using distiHation alone. The most common approach for CO removal is chemical conversion to CO2 using an oxidation catalyst in the feed air to the air separation unit. The additional CO2 which results, along with the CO2 from the atmosphere, is then removed by a prepuritication unit in the air separation unit. 

Hot potassium carbonate processes are intended for the removal of carbon dioxide, or the co-removal of hydrogen sulfide and carbon dioxide. As a result of the regeneration chemistry, these hot-pot processes are not suitable for the removal of hydrogen sulfide without significant carbon dioxide also in the untreated gas stream. 

CO conversion is a function of both temperature and catalyst volume, and increases rapidly beginning at just under 100°C until it reaches a plateau at about 150°C. But, unlike NO catalysts, above 150°C there is Htde benefit to further increasing the temperature (44). Above 150°C, the CO conversion is controUed by the bulk phase gas mass transfer of CO to the honeycomb surface. That is, the catalyst is highly active, and its intrinsic CO removal rate is exceedingly greater than the actual gas transport rate (21). When the activity falls to such an extent that the conversion is no longer controUed by gas mass transfer, a decline of CO conversion occurs, and a suitable regeneration technique is needed (21). 

B. K. SperoneUo, J. M. Chen, and R. M. Heck "Family of Versatile Catalyst Technologies for NO and CO Removal in Co-Generation," paper... 

Fig. 8.13. Cycle B2. Complex steam/TCR plant with CO> removal (after Lozza and Chiesa (7 ).

In gas reforming plants, e.g. the hot potassium carbonate process for CO removal, sodium metavanadate is used to prevent mild-steel corrosion". Banks reports" that this treatment does not reduce the rather high corrosion rate of Cu-30Ni in these plants. 

Catalytic Cycles. In the unpolluted troposphere, the two step sequence Rl, R2 was early recognized as the dominant source of HO (20,91,92) and HO as the dominant reactant for CO removal (93,94). 

Development of a CO remover employing microchannel reactor for polymer electrolyte fuel cells... 

In this study, we developed microchannel PrOx reactor to control CO outlet concentrations less than 10 ppm from methanol steam reformer for PEMFC applications. The reactor was developed based on our previous studies on methanol steam reformer [5] and the basic technologies on microchaimel reactor including design of microchaimel plate, fabrication process and catalyst coating method were applied to the present PrOx reactor. The fabricated PrOx reactor was tested and evaluated on its CO removal performance. 

Fig. 2. CO removal reactor integrated with microchannel plate 2.2. Experimental set-up...

For the practical use of this CO removal reactor, the microchannel reactor should be operated carefully to maintain operating temperature ranges because the reaction temperature is critical for the microchannel reactor performance such as CO conversion, selectivity and methanation as disclosed in the above results. It also seems that the present microchannel reactor is promising as a compact and high efficient CO remover for PEMFC systems. 

A microchannel reactor for CO preferential oxidation was developed. The reactor was consisted of microchannel patterned stainless steel plates which were coated by R11/AI2O3 catalyst. The reactor completely removed 1% CO contained in the Ha-rich reformed gas and controlled CO outlet concentration less than Ippm at 130 200°C and 50,000h. However, CH4 was produced from 180"C and CO selectivity was about 50%. For high performance of present PrOx reactor, reaction temperature should be carefully and uniformly controlled to reach high CO conversion and selectivity, and low CH4 production. It seems that the present microchaimel reactor is promising as a CO removal reactor for PEMFC systems. 

Decarbonilyzing (CO removal) enzyme 1H-3-OH-4-oxoQN-2, 4-dioxygenase BDN through the anthranilic acid pathway ... 

The rate of CO removal from the Pt surface is also affected by the presence of O2 in the gas phase, as demonstrated in Figure 12. In this experiment the catalyst, initially in equilibrium with 1 vol % CO (in N ), was suddenly exposed to a feedstream of 0.7 vol % O2 (in 1 7 It can be seen from Figure 12 that the Pt-CO band decays much faster in O2 (Curve B) than in (Curve A for reference). This indicates that the surface reaction between CO and oxygen is faster than the rate of CO desorption. 

Since CO acts as a poison to the proton exchange membrane fuel cell in the 50 ppm range, it has to be removed before feeding the H2 enriched gas to the fuel cell. This CO removal occurs in the PROX reactor, where Pt/Al203 catalysts are common, even though some interest in Au-based catalysts is growing due the lower cost of the active phase [48]. 

DEA Societe National des Petrols d Aquitaine SNPA-DEA 90-120 500-1100 high acid-gas pressure desirable (<50 psi) Yes, down to 4 ppm Some COS removed Yes, <1%... 

A number of system approaches can be used to clean up the fuel feed. These include pressure swing adsorption, membrane separation, methanation, and selective oxidation. Although selective oxidation does not remove CO2, it is usually the preferred method for CO removal because of the parasitic system loads and energy required by the other methods. In selective... 

For MCFC SOFC, no high temperature shift, low temperature shift, nor CO removal required. 

Hydrogen from coal with CO, removed and stored underground 13.2... 

Iodine pentoxide is used for analysis of carbon monoxide and for CO removal from air. It also is used as an oxidizing agent in other oxidation reactions. 

C 0 and H O, unavoidable by-products of alcohols synthesis. Considering chemical reactions of table H, water and carbon dioxide appear as equiva-lentby-products due to shift conversion equilibrium, equation (1). Most other low temperature alcohol synthesis catalysts have a rather high shift activity as well. CO removal fhom reacted syngas of synthesis loop, before recycling to reactor, leads to a significant decrease of water formation which, in turn, results in a lower water content in the raw alcohols, leading to simplified fhactionation-dehydration processes. 

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