Kinetic study of template removal of MCM-41 derived from rice husk ash

Abstract

Molecular sieves MCM-41 were synthesized from rice husk ash (RHA) as alternative sources of silica, called RHA MCM-41. The material was synthesized by a hydrothermal method from a gel with the molar composition 1.00 CTMABr:4.00 SiO 2 :1.00 Na 2 O:200.00 H 2 O at 100 °C for 120 h with pH correction. The cetyltrimethylammonium bromide (CTMABr) was used as a structure template. The material was characterized by X-ray powder diffraction, FTIR, TG/DTG, and surface area determination by the BET method. The kinetics models proposed by Ozawa, Flynn-Wall, and Vyazovkin were used to determine the apparent activation energy for CTMA ? species decomposition from the pores of MCM-41 material. The results were compared with those obtained from the MCM-41 synthesized with silica gel. The synthesized material had specific surface area, size, and pore volume as specified by mesoporous materials developed from conventional sources of silica.

Applications of inorganic–organic mesoporous materials constructed by self-assembly processes for removal of benzo[k]fluoranthene and benzo[b]fluoranthene

“…(Si-O-Si) in the MCM-41 could be observed at 1085 (m as , Si-O), 802 (m s , Si-O), and 460 cm -1 (d, Si-O-Si)[39,41,45].…”

Comparison of Kinetic Study of CTMA+ Removal of Molecular Sieve Ti-MCM-41 Synthesized with Natural and Commercial Silica

“…According to results of Table 1, that show the values of apparent activation energy for conversion levels from 5 to 90 %, the presence of titanium in the MCM-41 favor minor apparent activation energy values for CTMA + removal from the porous system of Ti-MCM-41 (SG) and (RHA) compared to RHA-MCM-41 and MCM-41 synthesized by Braga et al 10 and Souza et al 15 , that found values of Ea of 221 and 166 kJ mol -1 , respectively 15,17 . In previous study Fontes et al 1 observed that the increase of Ti in MCM-41 resulted in a gradual decrease apparent activation energy for CTMA + removal, which confirm the lower Ea values to the Ti-MCM-41 (SG) and (RHA) when compared to other MCM-41 of literature 18 .…”

“…In previous study Fontes et al 1 observed that the increase of Ti in MCM-41 resulted in a gradual decrease apparent activation energy for CTMA + removal, which confirm the lower Ea values to the Ti-MCM-41 (SG) and (RHA) when compared to other MCM-41 of literature 18 . According to Braga et al 17 the hydrophilic part of surfactant, which has positive charge, interacts with the surface of the pore of mesoporous MCM-41 material via coulomb forces. The apparent activation energy Comparison of Kinetic Study of Ctma+ Removal of Molecular Sieve Ti-Mcm-41 Synthesized with Natural and Commercial Silica involved in the removal of CTMA + located within the pores of molecular sieve provides the magnitude of the interactions between the template and silica 17 .…”

“…According to Braga et al 17 the hydrophilic part of surfactant, which has positive charge, interacts with the surface of the pore of mesoporous MCM-41 material via coulomb forces. The apparent activation energy Comparison of Kinetic Study of Ctma+ Removal of Molecular Sieve Ti-Mcm-41 Synthesized with Natural and Commercial Silica involved in the removal of CTMA + located within the pores of molecular sieve provides the magnitude of the interactions between the template and silica 17 . The Ti-MCM-41 (SG) and Ti-MCM-41 (RHA) showed near values for the two silica sources used confirming that the RHA showed similar chemical interaction as commercial silica used in the synthesis of Ti-MCM-41.…”

Kinetic study of the catalytic pyrolysis of elephant grass using Ti-MCM-41

“…Ti-MCM-41 molecular sieve was hydrothermally synthesized using experimental procedure adapted from literature syntheses described in Braga 6 to obtain gel with the following molar composition:1.00 CTMABr: 4.00 SiO 2 : xTiO 2 : 1 + x Na 2 O: 200.00 H 2 O. The "x" value was set so that the Si / Ti molar ratio remains equal to 50.…”