Preparation Of Ni/Sepiolite Catalyst And Its Application In Synthesis Of P-Amino-benzoic Acid

Preparation methods, by which the sepiolite particles refined, activated, surface modified and nickel particle catalyst loaded on sepiolite, were introduced in detail in this paper. In order to improve the surface structure of sepiolite, refining and acid attacking method were adopted. The appearance of processed sepiolite was very different from the raw material in the SEM photo: those large and gathered fibers had been changed into fine. However, the original smooth surface of sepiolite became very rough. Thus it was perhaps a proper way to modify the surface but the specific surface area was not changed.The experimental factors which can influence the growth of silicate crystal such as temperature, time and concentration were discussed in detail. From the result of the analyses we found that temperature and concentration were more important factors than time . From the point of surface configuration, the covered state of well-distributed particles and compact texture are premise or basis to obtain an ideal covering of metal salt over the surface of sepiolite.Preparation of nickel/sepiolite catalyst by hydrothermal process ,which was the main content in this paper ,was influenced by many factors such as concentration of solution ,time, and temperature of crystallization , temperature of reduction ,size of fiber and so on .The catalysis performance of the production was resulted from these factors. In order to obtain an active catalyst it is essential to maintain longer time of hydrothermal, 12-24 h was preferred. The particle size of nickel could be controlled by adjusting the reducing temperature.Synthesis of p-amino-benzoic acid which is an important medical intermediate under the catalysis of nickel/sepiolite catalysis was another topic. The optimal process conditions were: reaction temperature is 136℃, pressure is 3.1MPa,dosage of catalyst is 6% ,consistency of the raw material solution is 8%. Under this conditions, content of p-amino-benzoic acid is more than 85% with yield, greater than that of reported in reference. Nickel/sepiolite catalyst was applied instead of nickel. This process developed the new use of such catalyst as metal/sepiolite series. ...