Boreskov Institute of Catalysis of the Siberian Branch of Russian ...

OP-V-15An effect of preliminary RH carbonization conditions and other conditions of the processesof the alkali activation and the high-temperature leaching of SiO 2 by the mixture ofK 2 CO 3 /Na 2 CO 3 on properties of the preparing materials was investigated. It was showed, thatthe carrying out the carbonization in fluidized catalyst bed (T = 450–600 °C, contact time τ ~ 1sec, molar ratio of air oxygen to carbon of RH α ∼ 2, catalyst of deep oxidation CuO + MgO +Cr 2 O 3 /γ-Al 2 O 3 with granule’s size 2–3 mm) of leads to preparation of carbon-silica compositeswith better properties for preparation of the final carbons, than in case of pyrolysis.In Table 1, the results of an investigation of an effect of activation temperature on textureand adsorptive properties in relation to hydrogen and methane of the microporous carbonsprepared from RH, carbonized in fluidized catalyst bed at 500 °C are listed.Table 1. Activation temperature effect on texture and adsorptive properties of microporouscarbon samples obtained at different temperatures by KOH activation.A BET ,m 2 g –1V Σ /V μ , mlg –1Vol. microporequota, %H 2 adsorptive capacity,w. % (50 bar, 77 K)700 3170 1.77/1.45 81.9 4.7 28750 3450 2.01/1.68 83.6 5.7 27800 3360 2.18/1.87 92.3 6.3 33850 3170 2.26/1.74 77.0 5.8 34900 3210 2.97/1.48 49.8 6.2 41Activationtemperature, °CCH 4 adsorptive capacity,w. % (60 bar, 273 K)The analogies of the materials – microporous carbons, such as Maxsorb (Kansai Coke andChemical Co Ltd., Japan) are produced from petroleum coke and pitch also by KOHactivation at 700–800 °C but through a preliminary treatment of the precursors byconcentrated nitric acid that leads to mordant and toxic wastes. In addition, these materialspossess lower texture characteristics (A BET about 2700 m 2 g –1 , V μ about 1.2 ml g –1 ) [4]. Acomparison of the technical conditions leads to a resume that the proposing method is cheaperand environmentally more appropriate.In Table 2 the data on an effect of temperature on mesoporous carbons properties areshowed. The carbons were prepared by high-temperature leaching of SiO 2 from RH,carbonized in the fluidized catalyst bed reactor, by pyrolysis in inert atmosphere and fromnon-carbonized RH.Table 2. Effect of the leaching temperature on texture properties of mesoporous carbonsprepared from RH by high-temperature leaching with equimolar Na 2 CO 3 /K 2 CO 3 mixturePretreatmentconditionsT, °CVol.A BET ,m 2 g –1 V Σ /V µ , ml g –1 mesoporequota, %Deep of graphitization,% (by XRD)Ash content,%FCB 1) , 500 °C 750 1190 1.11/0.20 82.0 0.0 1.7FCB, 500 °C 800 1485 1.36/0.29 78.7 0.0 2.4FCB, 500 °C 850 1447 1.24/0.31 75.0 0.0 4.5FCB, 500 °C 900 1581 1.44/0.31 78.5 0.0 2.0FCB, 500 °C 950 776 0.88/0.21 76.1 39.5 1.8FCB, 500 °C 1000 652 0.84/0.13 84.5 46.5 2.3Pyrolysis, 400 °C 900 1479 1.17/0.40 65.82) - 4.1- 3) 900 1350 1.00/0.49 51.0 - 4.51) – FCB – fluidized catalyst bed; 2) – not investigated; 3) – raw RH was used197