Effect of methanol content in commercial formaldehyde solutions on the porosity of RF carbon xerogels

Abstract

Methanol is used commercially as a stabilizer in solutions of formaldehyde to prevent its precipitation. However, the methanol content of commercially available formaldehyde solutions differs from one supplier to another. The pH, dilution and R/F ratio have been demonstrated to be interdependent variables that can be manipulated to tailor the porous properties of RF carbon xerogels. This work considers the methanol contained in formaldehyde solutions as a new variable to be studied in conjunction with those just mentioned. For the purpose of this study, the influence of methanol on the final porous properties of RF carbon xerogels has been evaluated. It was found that carbon xerogels synthesized using formaldehyde solutions with lower concentrations of methanol showed a higher total pore volume and pore size, and in turn, a lower density and a greater porosity. The porosity of RF carbon xerogels could therefore be radically modified depending on the commercial formaldehyde solution used for their synthesis.

Desiccant capability of organic xerogels: Surface chemistry vs porous texture

“…silica gel) are presented in Table 1. These differences on the porosity between these xerogels are consequence of the variables used for each sample during the synthesis process, as can be found in literature [17,18,21]. Differences between the micromesoporosities of the samples were determined from N 2 adsorption-desorption isotherms, as shown in Fig.…”

“…In addition to the large number of variables that need to be controlled, it has been shown that there exists a synergy between them. For this reason, statistical programs have been applied to allow the simultaneous study of all of these variables, allowing to designed porous properties for specific applications [18,21].…”

Superhydrophobic and breathable resorcinol-formaldehyde Xerogels

“…Resorcinol-formaldehyde xerogels were prepared according to Pekala's method described elsewhere. 22,40 Briefly, solid resorcinol was dissolved by magnetic stirring in deionized water until total solution. At the same time the formaldehyde is mixed with the methanol in another glass baker.…”

“…[17][18][19] Organic gels in general, and resorcinol/formaldehyde (RF) resins in particular, are polymeric systems that show tremendous versatility in terms of developing tailored porous textures. Since the seminal work of Pekala, [20] a number of works have detailed the effect of different synthesis variables on the final three-dimensional structure of the RF gels, [21][22][23][24][25][26] which in turn determines the porosity of the materials. As a consequence, RF gels are nowadays synthesized with pore sizes and volumes adapted to the requirements of a given application.…”

Experimental Investigation of Methanol Conversion Factor to Formaldehyde in a Pilot Reactor

“…Therefore, studies on methane oxidation show that methane with significant amount under 600 °C does not oxidize, while, as already mentioned, formaldehyde begins to decompose at temperatures below this. Formaldehyde is used because of elimination of bacteria as an antiseptic solution [16][17][18][19].…”