CO is an invisible killer that severely threatens the safety of trapped personnel in fire disasters. The existing CO removal approaches are passive and ineffective, which could not satisfy the emergency rescue needs. An active and synchronous CO removal approach (ASCR) based on catalytic oxidation is proposed. By spraying dry powder extinguishant and catalyst powder, the isolation layer and oxidation layer are formed on the fuel surface. CO removal is achieved by both combustion suppression and CO oxidation methods. The synthesized Co-La 0.1 catalyst exhibited superior catalytic activity, thermal stability , and selectivity, which met the application requirements of the ASCR approach. The results of lab-scall tests demonstrated that the CO concentration in the smoke flow decreased from 135 ppm to 0 ppm immediately once employing the ASCR approach. Full-scale tests in the confined tunnel further verified the practical application performance. With spraying 2 kg extinguishant and 0.9 kg catalyst powder, CO concentration increased merely by ∼ 20 ppm within 50 min, which was far lower than that without taking any disposal measures (∼800 ppm). This approach can effectively control the CO concentration below the safety threshold in fire disasters and is significant for emergency rescue.
Pengcheng Wang,Jun Liu,Peiwen Xu,Xinzhen Feng,Weijie Ji
Three morphologically uniform γ-Al 2 O 3 crystallites [Al 2 O 3 hexagonal plates (Al 2 O 3 -HP), stacked hexagonal plates (Al 2 O 3 -SHP) and rods (Al 2 O 3 -R)] were controllably synthesized. The Co-Mo oxide precursor was loaded on these γ-Al 2 O 3 substrates via aqueous incipient wetness impregnation and transformed to the sulfides under 10% H 2 S/H 2 (v/v) atmosphere. The mainly exposed facet of Al 2 O 3 -HP and Al 2 O 3 -SHP was identified to be the (1 1 0) and (1 0 0)/(1 1 1), respectively; whereas a polycrystalline structure was observed over Al 2 O 3 -R. The original structural feature of oxide precursors, i.e., 2D polymeric/monomeric as well as 3D polymeric/MoO 3 species substantially varied over Al 2 O 3 -HP, Al 2 O 3 -SHP, and Al 2 O 3 -R, which in turn determines the effectiveness in sulfidation of surface oxide precursors. The richness of MoS 2 /Co 9 S 8 /Co-Mo-S species, and less fraction of partially sulphurated CoMoO x S 2 as well as CoO x /SO x 2− entities were recognized over Al 2 O 3 -HP. Based on the areal activity at 250 °C, the sulfides-Al 2 O 3 (1 1 0) interface is approximately 6–13.8 times more active than the poly-crystalline or commercial γ-Al 2 O 3 supported sulfides for water gas shift (WGS) in a hydrogen-rich stream. The sulfides-Al 2 O 3 (1 1 0) interface also notably outperformed the sulfides-Al 2 O 3 (1 0 0)/(1 1 1) interfaces for the reaction.
Four methods were adopted to prepare samples 20%NiO/Al 2 O 3 with calcination fixed at 500 °C, which were then reduced into 20%Ni/Al 2 O 3 and used as catalysts for reaction of selective methanation of CO in H 2 -rich gas (CO-SMET). XRD and TPR measurements indicate that nickel aluminates were formed in the calcined samples and their formation was influenced by preparation methods. Higher temperatures were required to reduce the calcined samples more efficiently and to achieve a higher catalytic activity for CO-SMET. Among the four methods, the precipitation method using ammonium carbonate as precipitant produced the highest catalytic activity both for CO methanation and for CO 2 methanation after reduction at 800 °C for 2 h. The calcined sample 20%NiO/Al 2 O 3 prepared with the method was therefore used as support and impregnated with Ru 3+ solution. Ru addition promoted reduction of Ni 2+ ions in the calcined sample even at the low temperatures of 400 °C and 500 °C. The catalyst 1%Ru–20%Ni/Al 2 O 3 reduced at 500 °C thus had a superior performance, removing CO to ca. 30 ppm with a selectivity as high as 75% at reaction temperature of 220 °C.
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