Process For The Catalytic Purification Of 1,2-propylene Glycol

1,2-propylene glycol is one of the most important organic chemicals. In this thesis a purifying process of 1,2-propylene glycol coproduced from transesterification was studied. The process are divided two steps, catalytic conversion of the impurities containing in the raw 1,2-propylene glycol and recovery of pharmaceutical grade 1,2-propylene glycol. Different solid acid catalysts, which were prepared through sol gel methods, were studied for conversion of impurities in 1,2-propylene glycol using fixed bed flow reactor under atmospheric pressure and different reaction conditions. The catalyst samples were respectively characterized by BET, XRD and IR. The distillation conditions including overhead pressure, reflux ratio for the recovery of 1,2- propylene glycol were studied.It has been found that 40wt%SiO2 amorphous aluminosilicate prepared through sol gel exhibits good catalytic performance for conversion of impurities containing in the raw 1,2-propylene glycol under the condition of 100°C reaction temperature, 0.98h-1 liquid hourly space velocity and atmospheric pressure. The proper distillation condition is overhead pressure 50mmHg and reflux ratio 2.The GC method suitable for analysis of the impurities in the 1,2-propylene glycol was developed and confirmed.The purified 1,2-propylene glycol can meet the standard of pharmaceutical grade, with purity of 1,2-propylene glycol being greater than 99.5%, color(APHA) smaller than 10#, water content in 1,2- propylene glycol smaller than 0.2%.