Advantageous Effect on Porosity of Template Carbon Materials by Residue of Templates

Abstract

Porous ceramic materials are generally used for templates in synthesis of new porous carbon materials by template method. In the synthesis procedure, template materials are finally dissolved by acid or alkaline solution. Improvement of carbon content in the carbon materials by the process is expected to be effective for advancement of porosity and specific surface areas of the specimens, therefore realization of elimination of templates to a maximum extent is assumed to be desirable. In this report, we have prepared several porous carbon materials by the use of natural soils or clays for templates, and improved their carbon content by ammonium chloride NH 4 Cl treatment. However, their specific surface areas demonstrate a tendency to decrease contrary to the expectation. The result suggests that the original carbon specimens are rather effective in porosity, and the residue of templates can also play a useful part for specific surface areas of the carbon materials. This effect is attractive for improvement of synthesis process of porous carbon materials, which have high specific surface area, from viewpoints of practical applications.

Effects of Synthesis Conditions and Starting Materials' Properties on Porosity of Template Carbons

“…At first, their hysteresis loops in the isotherms have different shapes, and these features indicate that their porous configurations are also different. Tl is assumed to have wedge type pores, and T2 is assumed to have bottleneck type pores [18][19][20]. In addition, Figure 3 shows H 2 0 absorption by T1 and T2.…”

“…We have used 2 types of natural porous materials (Tl and T2, some kinds of volcanic ash soils or clays, products of SEIWA PRO Corp., Osaka, Japan) for templates in this research. The detailed particulars of the materials are described in the previous reports [15][16][17][18]. They are almost composed of allophanic soils.…”

“…In the previous reports, we have prepared several porous template carbon materials using several kinds of natural soils or clays and minerals for templates [15][16][17][18]. The carbon specimens have certain unique pore developments, and some of them show more effective adsorbability of several kinds of organic solvents' vapors as compared with a common activated carbon.…”

Adsorption and desorption behavior of water and organic vapor of allophanic soil<b>–</b>templated porous carbon materials

“…Figure 1 shows N 2 adsorption and desorption isotherms at 77 K of the reference and the templated porous carbon specimens. The template materials T1 (soil consists of allophane and quartz) and T2 (volcanic ash soil consists of allophane and wollastonite) are identical with the templates described previously, 18), 19) and the carbon specimens A, C and D are corresponding to the specimens SA4, 19) S3 and S5 18) in the previous reports. The reference showed no hysteresis in the isotherm [ Fig.…”

“…We synthesized templated porous carbon specimens with reference to the method described previously, 18), 19) and the carbon specimens were carbonized at 973 K or 1173 K. We used D(+)glucose, furfuryl alcohol (products of Wako Pure Chemical Industries Ltd.), and brown sugar (made from sugarcane, product of Okinawa Kokuto Co. Ltd.) as carbon ingredients and 2 kinds of natural allophanic soil purchased in Japan (as garden supplies marketed by Seiwa Pro Co. Ltd.) as template materials. The features of the allophanic soils are similarly as described in the previous report.…”