One-pot synthesis of carbonaceous monolith with surface sulfonic groups and its carbonization/activation

Deactivation of sulfonated hydrothermal carbons in the presence of alcohols: Evidences for sulfonic esters formation

“…The deactivation of sulfonated carbons had been ascribed, at least in part, to extraction of soluble sulfonated material into the liquid phase, both in the case of carbon prepared by pyrolysis of glucose [33] and in hydrothermal carbons prepared from ptoluenesulfonic acid/glucose/resorcinol mixtures [14]. The sulfur analysis of the recovered catalyst (Table 1) seems to confirm this hypothesis, although a loss of 18% in sulfur content cannot account for a loss of 65% in activity (Table 3).…”

“…In fact, sulfonated carbons obtained by partial carbonisation of glucose or cellulose have been used as catalysts for esterification reactions [9][10][11][12][13], as well as monoliths prepared by one-pot synthesis in the presence of p-toluenesulfonic acid [14]. Sulfonated mesoporous carbon was obtained by replication of SBA-15 pores through carbonisation of sucrose, leading to highly active solids [15].…”

“…This is also the case of acid catalysts used in esterification reactions. In the case of sulfonated carbons, deactivation has been attributed to leaching of soluble polycyclic aromatics with sulfonic groups [14,33], simple physical loss of catalyst [15], or hydrolysis of sulfonic groups [34]. Other acid catalysts have also shown a similar behaviour with respect to stability in esterification reactions, that have been explained by leaching problems in sulfated zirconia [35], hydrocarbon accumulation in SAC-13 [36] and organosulfonic silica [37], and several reasons, including leaching of sulfonic species, water and glycerol adsorption, and even reaction with methanol in the case of sulfonic-acid modified SBA-15 [38,39].…”

Sulfonated carbon catalyzed oxidation of aldehydes to carboxylic acids by hydrogen peroxide

“…The -SO 3 H group can be identified by the peaks at 1226, 1167 and 1127 cm −1 . Additionally, the peak at 1031 cm −1 is attributed to the S = O stretching mode of -SO 3 H group [36]. These absorption bands related to -SO 3 H group imply that -SO 3 H groups are functionalized on carbon.…”

“…This implies that the sample tends to form graphene in the sulfonation process; however, the framework is still amorphous and far from graphitization (d 002 = 3.354Å). The weak and broad peak at 2θ of 35 o −50 o is ascribed to the (1 0 1) plane (d 101 = 2.14Å), representing the a axis of the graphite structure [36]. This type of XRD patterns is known to be characteristic to the carbon states described as clusters composed of small fragments of graphene planes plus some amount of disorganized carbon.…”