FTIR Characterization On Preparation And Application Of Novel Solid Acids

Natural and reproducible biomass materials are expected to be utilized as a promising green approach to develop novel solid acids for meeting the requirements of modem green chemistry technology. In this thesis, FTIR characterization on preparation of novel solid acids is carried out by means of transmission and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) . The major work is now summarized as follows:1) Studies of the chemical composition changes of cotton cellulose in the charring process using sulfuric acid as dehydrating agent and sulfonation on chars from cotton were investigated by means of transmission FTIR spectroscopy. The results indicated that cotton cellulose was drastically decomposed and a large number of hydroxyl groups were dislocated in the charring process while the solid residues underwent a chemical transformation and rearrangement to give a condensed polycyclic aromatic structure. The SO₃H groups were absolutely bonded to condensed aromatic rings to a certain degree after sulfonation with oleum on chars from cotton. It was proved that a novel solid sulfonic acid was successfully prepared. In addition to this, effects of temperature,reaction time and concentrations of sulfuric acid solution on the solid residues of charring treatment were presented. It was suggested that char prepared at higher temperature within longer time was favorable to form a larger condensed polycyclic aromatic network. However, cotton charring at 80℃with 80 wt% concentration of sulfuric acid for 3 h was the optimal charting condition for sulfonation to obtain a relatively higher acidity of sulfonated char up to 2.58 mmol·g^-1.2) Characterization of the incompletely carbonized chars from bamboo pyrolyzed at low temperature under vacuumed atmosphere and sulfonated chars was investigated by use of transmission FTIR. Simultaneously, pyridine adsorption DRIFTS of chars from bamboo prepared by phosphate acid-catalyzed pyrolysis and dehydration of sulfuric acid were compared with those of sulfonated chars. The results confirmed that a novel solid sulfonic acid was prepared by sulfonation on char precursors from bamboo.3) The pyridine adsorption upon HTS zeolites occurred in desiccant vessel at room temperature. Desorption of pyridine upon HTS-1,HTS-2 and HTS-5 was investigated by a in-situ DRIFTS technique. The FTIR study demonstrated that there were two different Lewis acidity centers in Ti (â…£) with MFI framework, moreover, the internal titanols (silanols) were another source of the acidity centers of HTS zeolites.