Carbon calcination

Recently, the influence of the preparation method of various MgO samples on their catalytic activity in the MPV reaction of cyclohexanone with 2-propanol has been reported 202). The oxides were prepared by various synthetic procedures including calcination of commercially available magnesium hydroxide and magnesium carbonate calcination of magnesium hydroxides obtained from magnesium nitrate and magnesium sulfate sol-gel synthesis and precipitation by decomposition of urea. It was concluded that the efficiency of the catalytic hydrogen transfer process was directly related to the number of basic sites in the solid. Thus, the MgO (MgO-2 sample in Table IV) prepared by hydration and subsequent calcination of a MgO sample that had been obtained from commercially available Mg(OH)2 was the most basic and the most active for the MPV process, and the MgO samples with similar populations of basic sites exhibited similar activities (Table IV). 

In a similar experiment, 2.5 g of zinc oxide prepared by precipitation from zinc nitrate solution by sodium carbonate, calcination, and attempted reduction under similar conditions as previously employed, gave a catalyst of surface area of 40 m2/g, which yielded less than 10 9 kg of methanol per square meter of the catalyst per hour under the standard conditions used for the testing of the copper catalyst. The zinc oxide was in its wurtzitic crystal modification as in most laboratory as well as industrial catalysts, was free of surface impurities, and had a morphology shown in Fig. 4. Details of the pore structure of this catalyst are given in reference (38). 

Gupta, H. and Fan, LS. Carbonation-calcination cycle using high reactivity calcium oxide for carbon dioxide separation from flue gas. Industrial Engineering Chemistry Research, 2002, 41, 4035-4042. 

On the other hand, hydrogen membranes and the reaction-based processes using solid sorbents can separate CO2 while operating at the elevated temperatures of the gasifier. Such methods utilize the carbonation/ calcination cycle of a solid metal oxide (MO). ... 

Typical fillers calcium carbonate, calcinated clay, aluminum hydroxide, magnesium carbonate, magnesium hydroxide, antimony trioxide, calcium borate, huntite, hydromagnesite, zinc oxide, talc, silica... 

Typical concentration range generally >40 wt% calcium carbonate, calcinated kaolin, talc - 20-40 wt% carbon fiber 5-30% (depending on aspect ratio) " titanium dioxide - 1 wt% (occasionally concentrations of 10 wt% are found in thin sections) " ferromagnetic powder - up to 90 wt% " stainless steel fiber - 2-3 wt% " nickel fibers for magnetic properties -10-30% starch in biodegradable products - 4-8 wt% ... 

Co.l04 thermal decomposition of basic carbonate, calcined at different T 0.005-0.12 mol dm" KNO3 ... 

Magnesium oxide can be chlorinated quantitatively only in the presence of a reducing agent (CO). The reaction depends critically on the thermal pretreatment of the MgO magnesium carbonate calcined at 800°C is still very reactive. Commercial CO in cylinders is not suitable, since the H3it contains forms water, which damages the apparatus for this application CO is prepared in a small generator. 

Potassium carbonate. Calcined potash K2CO3 K2O 0.681 1.469 Source of K2O... 

Synonyms Bisodium carbonate Calcined soda Carbonic acid disodium salt Crystol carbonate Disodium carbonate Natron Sal soda Soda ash Soda calcined Sodium carbonate (2 1)... 

Fig. 6.6 Repeated carbonation/calcination cycles of naturally occurring limestone conducted in a TGA. The experiment was performed isothermally at 750 °C using a carbonation atmosphere containing 40 vol.% CO2...

Fig. 6.7 Pore size distribution of limestone in its a calcined and b carbonated form after being exposed to different numbers of carbonation/calcination cycles. Reprinted with the permission from Ref. [17]. Copyright 2005, American Chemical Society...

Fig. 6.15 SEM images of cycled CaO-based sorbents a sectioned spent sorbent particle, b re-activated/pelletized sorbent pellets, c morphology of the re-activated and calcined sorbent containing 10 % cement as a binder, and d morphology of the re-activated sorbent (containing 10 % cement as a binder) after 30 carbonation/calcination cycles. Reprinted from Ref. [47] with the permission from Dr. Ben Anthony, Copyright 2012...

Fig. 6.19 SEM images of a CaCOs nanoparticles with a mean size of 40 nm and b the material shown in a after being exposed to 100 carbonation/calcination cycles. Reprinted from Ref. [72], Copyright 2009, with permission from Elsevier...

Symonds RT, Lu DY, Macchi A, Hughes RW, Anthony EJ (2(X)9) CO2 capture from syngas via cyclic carbonation/calcination for a naturally occurring limestone modelling and bench-scale testing. Chem Eng Sd 64 3536-3543... 

Li ZS, Cai NS, Huang YY (2006) Effect of preparation temperature on cyclic CO2 capture and multiple carbonation-calcination cycles for a new Ca-based CO2 sorbent. Ind Eng Chem Res 45 1911-1917... 

Figure 4 Predominance diagram for magnesium carbonate calcination...

Wang W, Ramkurmar S, Li S, Wong D, Iyer M, Sakadjian BB, et al. SubpHot demonstration of the carbonation-calcination reaction (CCR) process high-temperature CO2 and sulfur capture from coal-fired power plants. Ind Eng Chem Res 2010 49 5094-101. 

The Ohio State University proposed a method to combine coal gasification with a carbonation/calcination reaction (CCR) process to produce hydrogen [27]. CCR is also a sorption-enhanced process. In contrast to the ZECA process, the CCR method uses CaO to promote WGS reaction as follows ... 

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