• Korean Chemical Engineering Research
• /
• v.52 no.1
• /
• pp.63-67
• /
• 2014

The effects of reactant composition on the particle size distribution, synthetic yield, and density of Phenol-formaldehyde bead were examined in the synthesis of resol-type phenolic resin. Decrease of the content of DI water as dispersion media can increase the viscosity of suspension, which may cause the difference of particle size distribution and aggregation. The average particle size of synthesized beads was also decreased with the increasing content of stabilizer which can affect the interfacial area. The amount of crosslinking agent showed no effect on the size distribution and synthetic yield, but it made a decrease in the density of synthesized bead due to the macropore in the bead.

• Korean Chemical Engineering Research
• /
• v.58 no.4
• /
• pp.618-623
• /
• 2020

Spherical phenolic resin beads were synthesized by suspension polymerization at 98 ℃ from phenol, ortho-cresol, formaldehyde, with triethylamine as a basic catalyst, and spherical phenol-cresol copolymer resin beads with relatively low crosslinking density as well. Phenol reacts with formaldehyde at two ortho- and one para- positions to form a crosslinked structure, but ortho-cresol instead of phenol reduces the crosslinking density during copolymerization due to the methyl group at a ortho- position. As a result, spherical phenol-cresol copolymer beads showed more shrinkage with decreasing apparent density compared to the spherical phenol beads when carbonized at 700 ℃ under nitrogen. As the molecular weight of the cresol oligomer increases, the pore radius of the carbonized copolymer beads decreases, which is consistent with the density and shrinkage results. It was confirmed that the characteristics such as density decrease, shrinkage, yield and so on during carbonization can be controlled by controlling the degree of crosslinking of the spherical phenolic resin particles with cresol.

• Korean Chemical Engineering Research
• /
• v.51 no.2
• /
• pp.279-284
• /
• 2013

The phenolic beads in macrosize range were obtained by suspension polymerization at $98^{\circ}C$ from phenol and formaldehyde in the presence of basic catalyst with a phenol to formaldehyde (P/F) range of 1:1~1:4, and they were carbonized to spherical carbon beads under nitrogen at $700^{\circ}C$. Thermal analysis on spherical phenolic beads obtained by suspension polymerization showed that the postcuring process is essential. In order to optimize the suspension polymerization, the effects of the P/F molar ratio, the pH of catalyst, and the molecular weight of stabilizer on the size distribution and yield of spherical phenol beads were examined separatively. The particle size was increased whereas the yield was decreased with P/F molar ratio. The increasing basicity of catalyst made the particle size to increase, while the molecular weight of stabilizer had more effect on the yield rather than on the particle size distribution. The thermal stability of the spherical phenolic beads obtained through postcure was also examined by TGA. The phenol beads of high P/F ratio still showed the weight loss at $220^{\circ}C$ even after postcure due to the high possibility of dibenzyl ether, while those of low P/F ratio showed the steady decrease in weight during $220^{\circ}C$ to $400^{\circ}C$, which showed that the optimal P/F ratio was 1:2.

• Journal of Industrial and Engineering Chemistry
• /
• v.67
• /
• pp.448-460
• /
• 2018

Copper nanoparticle-doped and graphitic carbon nanofibers-covered porous carbon beads were used as an efficient catalyst for treating synthetic phenolic water by catalytic wet air oxidation (CWAO) in a packed bed reactor over 10-30 bar and $180-230^{\circ}C$, with air and water flowing co-currently. A mathematical model based on reaction kinetics assuming degradation in both heterogeneous and homogeneous phases was developed to predict reduction in chemical oxygen demand (COD) under a continuous operation with recycle. The catalyst and process also showed complete COD reduction (>99%) without leaching of Cu against a high COD (~120,000 mg/L) containing industrial wastewater.